PCI Adjacent Box Beam Bridges 4-21-09

The State of the Art of 

Precast/Prestressed Adjacent Box Beam Bridges

209 West Jackson Boulevard, Chicago, IL 60606 Phone: 312-786-0300 Fax: 312-786-0353 http://www.pci.org email: [email protected]

PCI Publication Number __-__  Copyright © 2009 By Precast/Prestressed Concrete Institute First Edition, First Printing, 2009 All Rights Reserved  No part of this book may be reproduced in any form without the written permission of  the Precast/Prestressed Concrete Institute.

ISBN 0-937040-XX-X

This report has been prepared and reviewed as a Precast/Prestressed Concrete Institute (PCI) Committee effort to present the state of the art for design of and construction of precast/prestressed adjacent box beam bridges. Substantial effort has been made to ensure that all collected data and information included in this report are accurate. PCI, the committee members, and the quoted agencies cannot accept responsibility for any errors or oversights in the use of this material or in the preparation of any final design and engineering plans. This report is intended for reference by professional personnel who are competent to evaluate the significance and limitations of its contents and who are able to accept responsibility for the application of the material it contains. Actual conditions on any project must be given special consideration and more specific evaluation and engineering judgement may be required that are beyond the intended scope of this state of the art report. The contents of this report do not necessarily reflect the official views or policies of the agencies mentioned, and do not constitute a standard, or policy for design or construction. Details have been provided for  information only.

Printed in U.S.A.

ACKNOWLEDGEMENT

The subcommittee wishes to thank all those who participated in the development of this report. The subcommittee also extends its gratitude to the many individuals in the respective organizations of the members who contributed to this report for  their active participation either in developing the material or in editing and typing. The subcommittee expresses its appreciation to the support of the Precast/Prestressed Concrete Institute Committee on Bridges to embark on a major effort which will be a benefit to the precast concrete industry. Members of the Subcommittee on Adjacent Members: Kevin Eisenbeis, P.E., S.E. Tess Ahlborn, Ph.D., P.E. Dave Bracewell Vijay Chandra, P.E. David Deitz, Ph.D., P.E. Keith Kaufman, Ph.D., P.E. Richard Miller, Ph.D., P.E. Eric Steinberg, Ph.D., P.E.

Harrington & Cortelyou, Inc. (Chair) Michigan Technological University Coreslab Parsons Brinckerhoff, Inc. Palmer Engineering Co. Knife River Corp. University of Cincinnati Ohio University

The subcommittee acknowledges the contribution made by Dr. Richard Miller, University of Cincinnati, for reduction of the survey data into electronic format.

TABLE OF CONTENTS

Page 1. 1.1 1.2

Introduction Overview .......................................................................................1 Executive Summary ......................................................................2

2. 2.1 2.2

Adjacent Member Bridges Basic Characteristics .....................................................................3 Railroad Bridges ...........................................................................4

3. 3.1 3.2

Composite Superstructure General ..........................................................................................6 Types .............................................................................................6

4. 4.1 4.2 4.3 4.4

Non Composite Superstructure General ..........................................................................................8 Types .............................................................................................8 Typical Sections ............................................................................9 Design .........................................................................................12

5. 5.1 5.2 5.2.1 5.2.2 5.2.3 5.2.4 5.3 5.3.1

5.3.2

Joints General ........................................................................................13 Details .........................................................................................13 Shear Keys ..................................................................................13 Welded Connections ...................................................................16 Transverse Reinforcement ..........................................................17 Current Practice ..........................................................................19 Design .........................................................................................19 AASHTO Standard Specifications for Highway Bridges (2002) .......................................................20 AASHTO LRFD Bridge Design Specifications (2004)..............20

6.

Continuity ..................................................................................21

7. 7.1 7.2 7.3

Bearings General ........................................................................................22 Survey Questionnaire Response Summary .................................22 Railroad Structures......................................................................23

8. 8.1 8.2 8.3

Maintenance Issues General ........................................................................................24 Inspection ....................................................................................24 Load Ratings ...............................................................................25

Page 9. 9.1 9.2 9.3

Survey of Current Practice Introduction .................................................................................27 Data Collection/Survey Response...............................................27 Lessons Learned..........................................................................28

10. 10.1 10.2 10.3 10.4 10.5

Summary of Case Studies NASA Road 1 Bridge over I-45..................................................30 Mitchell Gulch Bridge, Colorado ...............................................30 Quaker City Bridge, Ohio ...........................................................30 BNSF Railway over Route 160, Missouri ..................................30 Route 100 over I-44, Missouri ....................................................30

11. 11.1 11.2

Summary of Current Research................................................31 UHPC ..........................................................................................31 NCHRP Projects .........................................................................32

12. 12.1 12.2 12.3 12.4

Conclusions General ........................................................................................34 Design .........................................................................................34 Fabrication ..................................................................................35 Construction ................................................................................35

13.

References ..................................................................................36

14.

Bibliography ..............................................................................38

Appendix A: Case Studies A.1 NASA Road 1 Bridge over I-45 A.2 Mitchell Gulch Bridge, Colorado A.3 Quaker City Bridge, Ohio A.4 BNSF Railway over Route 160, Missouri A.5 Route 100 over I-44, Missouri Appendix B: PCI New England Recommendations B.1 Sequence of Construction for Butted Box and Butted Deck Beam Superstructures (Skews < 30°) B.2 Sequence of Construction for Butted Box and Butted Deck Beam Superstructures (Skews > 30°) Appendix C: Survey Questionnaire Responses

LIST OF FIGURES

Page Figure 2.1

Elevation of a Continuous, Composite Adjacent Member Bridge ...................................................................................3

Figure 2.2

Typical Section of an Adjacent Member BridgeComposite Superstructure ...................................................................4

Figure 2.3

Typical Section of an Adjacent Member Bridge Non-Composite Superstructure...........................................................4

Figure 2.4

Typical Section of a Double-Cell Adjacent Member Railroad Bridge - Non-Composite Superstructure ............................................5

Figure 2.5

Typical Section of a Single-Cell Adj. Member Railroad Bridge - Non-Composite Superstructure ............................................5

Figure 3.1

AASHTO Composite Box Beam Bridge ............................................7

Figure 3.2

Inverted Tee Beam Bridge ..................................................................7

Figure 3.3

Composite Double-Tee Beam Bridge .................................................7

Figure 4.1

Non Composite Deck Bulb-Tee Beam Bridge....................................9

Figure 4.2

AASHTO Box Beams, Solid and Voided Slab Beams .....................10

Figure 4.3

AASHTO Double-Tee Girders .........................................................11

Figure 4.4

AASHTO Deck Bulb-Tee Girders ....................................................11

Figure 5.1

Partial Depth Shear Key for Box Beams, Solid and Voided Slab Beams ...........................................................................14

Figure 5.2

Full Depth Shear Key for Box Beams ..............................................15

Figure 5.3

Large Width Shear Key for Box Beams ...........................................16

Figure 5.4

Welded Attachment with Plate and Grouted Grouted Shear Shear Key...................17

Figure 5.5

Welded Attachment with Rod and Grouted Shear Key ....................17

Figure 5.6

Skewed Bridge – Square Post-Tensioning ........................................18

Figure 5.7

Skewed Bridge – Skewed Post-Tensioning ......................................19

Figure 5.8

Skewed Bridge – Staggered Post-Tensioning ...................................19

Figure 7.1

Plan View of Three Point Bearing System .......................................23

Figure 8.1

Reflective Deck Cracking Along Shear Keys Between Beams ........24

Figure 8.2

Degradation of Box Beams Below Reflective Cracking ..................24

Figure 8.3

Spalling on Exterior Face of Box Girder ..........................................25

Figure 11.1 FHWA Pi Girder Test Section ..........................................................31

1. Introduction 1.1 Overview

Precast pretensioned adjacent member bridges, consisting primarily of concrete box  beams, have been in use since 1950 in the United States. Other non-box elements, including tee-beams, multi-stemmed tees, inverted tees, deck bulb-tees, solid and voided slab beams, and U-shaped beams are also used in adjacent member bridges. Recent trends show an increase in the use of adjacent, non-box, non-I-beam bridge  beam elements. Although box beam elements are frequently used in an adjacent configuration with top flanges in close contact, they can also be used in a spread configuration, similar to conventional I-beam bridges. The 2006 National Bridge Inventory (NBI) shows there are 53,874 box beam bridges presently in service in the United States. Of this total, 9,988 (18.5%) are of spread configuration, with the balance adjacent. Of the total, 8,326 (15.5%) are multiple spans made continuous, with the balance simple spans. According to the 2006 NBI, box beam bridges account for 9.0% of the total 597,340  bridges in the United States. Since box beam bridges are typically used for shorter  spans and the NBI only considers bridges with spans of 20 feet or more, the number  of these bridges is likely even higher. Precast concrete box beams are still widely used in new bridge construction today. Approximately one-third of precast bridges  built over the past decade are box beam bridges. Box beams are the most common element used in adjacent member bridges, and information on the usage of other  adjacent beam types is less readily available. Many agencies have refined their design and construction practices to improve the  performance of box beam bridges. In the late 1980s and early 1990s, problems associated with longitudinal reflective cracking above joints were reported and diagnosed. Refinements to previous practices have significantly reduced or eliminated this cracking issue. In response to the wide use of concrete box beam bridges, improvements in design and construction practices, and the recent increase in use of non-box adjacent member   bridges, the Precast/Prestressed Concrete Institute (PCI) Committee on Bridges established the Subcommittee on Adjacent Member Bridges. This subcommittee is charged with the task of preparing this report on the state-of-the-art of   precast/prestressed adjacent box beam bridges. This report presents a discussion of  current practices, responses to a survey of US states and Canadian provinces regarding box beam bridges, and selected case studies. Also included is a comprehensive reference list for related information. Conventional concrete spread I-girder and spread box beam bridges are not covered in this report at this time. The designer is referred to the extensive publications in the  bibliography for additional information on spread I-girder and box beam bridges.

1.2 Executive Summary

This report presents the state of the art on precast pretensioned box beam bridges. Adjacent box beam bridges are widely used in new bridge construction and have many advantages over other bridge types in speed and ease of construction, aesthetics, span to depth ratio and cost. Although early construction practices may have led to serviceability issues, improved practices have made the box girder bridge a viable, cost-effective structural system. A discussion on current practice, historical issues, lessons learned and improved performance of box girder bridges is provided. Much of the information presented is based on responses to a survey of US states and Canadian provinces. In the late 1980s and early 1990s, problems associated with longitudinal reflective cracking above joints were reported and diagnosed. Improvements in design and construction practice were developed and implemented. The PCI Committee on Bridges established the Subcommittee on Adjacent Member Bridges to investigate and report on developments in adjacent member bridges. This subcommittee developed the survey questionnaire, investigated case studies and prepared this report. Design, fabrication and construction practices that have been shown to improve the  performance of box beam girder systems are included. The focus of the survey and this study is on box girder bridges. Box girder bridges are considered adjacent member bridges because the box beam elements are in close contact with the adjacent beams. Other types of adjacent member bridges are discussed in this report due to the similarity in construction and the applicability of  details as related to box beams bridges. Lessons learned have been many, and indicate the importance of proper design, fabrication and construction to the effective performance of the integral structural system. For maximum structural performance, all important components should be incorporated into the box girder system. The use of grouted shear keys, composite deck slab, transverse tensioning and proper design, fabrication and construction techniques contribute to the successful performance of the system. The appendix to the report includes case studies of box girder bridges and adjacent slab bridges where the use of precast adjacent elements, shear keys, transverse posttensioning, and construction techniques are provided. The appendix also includes construction practice recommendations developed by the PCI Northeast Technical Committee, and the compiled survey data from the responding states, provinces, and other agencies.

2. Adjacent Member Bridges 2.1 Basic Characteristics

Adjacent member bridges incorporate a variety of precast prestressed beam types, spaced in close contact with adjacent beam elements. These bridges may include simple or continuous spans, utilizing integral or non-integral construction. Most new  box beam superstructures utilize composite construction with cast-in-place (CIP) concrete deck slabs (Figure 2.1 & 2.2). Composite superstructures in a spread configuration may incorporate conventional precast deck panels or precast concrete deck slabs mechanically anchored to the support beams. Some superstructures utilize non-composite construction, with the adjacent member top flanges acting as the riding surface or non-composite overlays applied to the adjacent member top flanges, as shown in Figure 2.3. Various combinations of precast concrete deck panels, CIP deck slabs and/or overlays are successfully used by the different US and Canadian agencies.

Figure 2.1 Elevation of a Continuous, Composite Adjacent Member Bridge

Span lengths of precast/prestressed adjacent member bridges typically range from 20 feet to 130 feet. Simple span lengths of up to 168 feet have been achieved with the use of adjacent deck bulb-tee girders. Longer span lengths are possible with the use of  continuity and longitudinal post-tensioning. Span lengths are dependent on specific  project design requirements, local beam availability and construction methodologies used. The designer is referred to the PCI Bridge Design Manual, Chapters 6 and 8, for  additional design guidelines.

Figure 2.2 Typical Section of an Adjacent Member Bridge - Composite Superstructure

Figure 2.3 Typical Section of an Adjacent Member Bridge - Non-composite Superstructure 2.2 Railroad Bridges

The railroad industry utilizes adjacent member construction in a large percentage of  railroad bridges. Many railroad bridges in the 25 to 50 feet range use curbed, noncomposite double-cell box beams with the top flanges serving as the ballast pan for  the track structure. Standard single-cell box beams and box-tee beams are available in span lengths from 19 to 48 feet and special designs can extend the span length to over  80 feet. Figures 2.4 and 2.5 show typical double-cell and single-cell box beam  bridges. Shorter span railroad bridges, typically shorter than 20 feet, use adjacent solid or hollow concrete slabs. Longer span precast/prestressed railroad bridges incorporate multiple, adjacent I-beams with integral concrete deck ballast pans or  non-composite single-cell adjacent box beams.

Figure 2.4 Typical Section of an Adjacent Member Railroad Bridge - Non-composite Superstucture

Figure 2.5 Typical Section of an Adjacent Member Railroad Bridge - Non-composite Superstucture

3. Composite Superstructure 3.1 General

Composite adjacent member bridges incorporate a variety of precast prestressed beam types, spaced in close contact with adjacent beam elements. For adjacent sections, composite toppings in the 5 to 6 inch range are common, compared to spread beam systems that use composite topping commonly in the 8 inch thickness range. In some instances, a non-structural overlay is provided over the cast-in place deck slab to  provide a replaceable wearing surface. Transverse connections are typically made between beams to prevent differential deflection and improve the distribution of live loads. Composite deck slabs can also assist in distributing the live load to the beam elements. Transverse connections, when used, are typically made using threaded rods, post-tensioning bars or posttensioning strands. In some instances, welded or bolted connections are utilized. The small longitudinal joint between abutting beams, typically referred to as the “shear key” or “keyway”, is normally filled with grout or an appropriate nonstructural sealant to prevent water leakage and moisture penetration between beams. Shear keys also assist with the load transfer between beams. Without an adequate transverse connection, differential movement between beams may lead to longitudinal cracking of grouted keyways and reflective cracking in the deck slab and overlay, if  one is present. Several different types of grouted keyways and transverse connections have been reported to provide good performance when used in conjunction with adequate transverse connections. The selection of a system for connecting adjacent member   bridges should consider initial cost, long-term maintenance costs, experience of the owner, capabilities of local contractors, and availability of materials. 3.2 Types

Composite adjacent member bridges may be constructed with box beams (Figure 3.1), solid or voided slab beams, tee beams, inverted tees (Figure 3.2), double stemmed tees (Figure 3.3), deck bulb-tees, U-shaped beams or tub sections. Abutting top flanges or beam sections are in close contact and allow the use of thinner  composite toppings. The American Association of State Highway and Transportation Officials (AASHTO) standard box beams, spanning from 40 to 127 feet, are commonly used by many agencies. Other adjacent member sections, such as the deck   bulb-tee girders, are regional in nature and subject to local availability. A number of states have their own standard products. Designers should check with their local precast producers or agencies on product availability before they begin design. The designer is referred to the PCI Bridge Design Manual, Chapters 6 and 8 for design procedures, design aids and examples.

Figure 3.1 AASHTO Composite Box Beam Bridge

Figure 3.2 Inverted Tee Beam Bridge (Shown in Spread Configuration)

Figure 3.3 Composite Double-Tee Beam Bridge

4. Non-composite Superstructure 4.1 General

 Non-composite adjacent member bridges are constructed by placing precast,  prestressed concrete box or other adjacent member beams next to each other so that a deck slab is not required to complete the structure. Often, a non-structural overlay such as a 2-inch thick asphalt concrete wearing surface is used to provide the riding surface. In some instances, such as secondary roads, a topping is not used because the surface of the precast beam adequately serves as the riding surface. The use of a waterproofing membrane is beneficial to reduce the intrusion of water and deicing salts between the adjacent members. The transverse connections and keyways used between adjacent non-composite members are similar to those used for composite members. Refer to Section 3.1 of  this report. 4.2 Types

 Non-composite adjacent member bridges are typically constructed with box beams, solid or voided slab beams, double-tee beams or deck bulb-tee girders. Abutting top flanges or beam sections are placed in close contact to serve as the wearing surface or  to support a non-structural overlay. AASHTO standard box beams, spanning from 40 to 132 feet, are commonly used by many agencies. Other adjacent member sections, such as the deck bulb-tee girders are regional in nature and subject to local availability. Deck bulb-tee girders generally span from 65 to 168 feet. A typical noncomposite deck bulb-tee girder bridge is shown in Figure 4.1. A number of states have their own standard products. Designers should check with their local precast producers or agencies on product availability before they begin design. The designer is referred to the PCI Bridge Design Manual, Chapters 6 and 8 for design procedures, design aids and example designs.

Figure 4.1  Non Composite Deck Bulb-Tee Beam Bridge 4.3 Typical Sections

Several typical sections are included for reference. See Figure 4.2 for typical AASHTO box beams, solid slab beams and voided slab beams. Typical AASHTO double-tee sections and deck bulb-tee sections are shown in Figures 4.3 and 4.4. Maximum spans shown in Figures 4.2 through 4.4 are for simply supported and noncomposite HS25 live load, with f’c = 7,000 psi. However, the sections are suitable for  use in composite construction as well.

Figure 4.2 AASHTO Box Beams, Solid and Voided Slab Beams

Figure 4.3 AASHTO Double-Tee Girders

Figure 4.4 AASHTO Deck Bulb-Tee Girders

4.4 Design

Continuity over piers is not normally used with the various standard beam sections in non-composite construction. Therefore, non-composite adjacent member bridges are typically designed as simple spans. Adjacent member highway beams have been designed according to AASHTO Standard Specifications or AASHTO LRFD Specifications. Railroad bridges are designed in accordance with the American Railway Engineering and Maintenance of  Way Association (AREMA) Manual for Railway Engineering. A number of states and Canadian provinces utilize their own or other state’s standard  products. Designers should check with their local precast concrete producers on  product availability before they begin design.

5. Joints 5.1 General

Adjacent member bridges require longitudinal joints between their members. Various details for this interface have been used to connect the adjacent members. Connecting adjacent members can serve two purposes. First, the joint can act as a water seal,  preventing water from seeping between the members which can lead to deterioration. Second, if certain details are applied, the connection can prevent differential deflections between adjacent members, transmitting loads applied to one member to the next, allowing the members to share live load during service. Different agencies have taken widely varying approaches to the treatment of  longitudinal joints. When joints are intended to transmit loads, some form of shear  key is often employed. Welded connections details are also in use by a few agencies. In some cases transverse reinforcement in the form of post-tensioning is extended across the joints to tie the elements together while for some systems no connection  between the adjacent members is provided. A composite deck slab can be utilized to  both reduce moisture penetration and contribute to the distribution of loads. Noncomposite toppings, sometimes used on secondary roads, can be used to provide a driving surface and water stop without participating in load distribution. In other  instances, the top flanges of the adjacent members serve as the riding surface. 5.2 Details

Joint details are largely based on regional preferences. Variations occur in the size, type and location of the joint as well as type and strength of material used to fill the  joints when shear keys are used. Transverse reinforcing details also vary considerably. Differences occur based on regional preferences in the amount, spacing, and type of reinforcement used. Placement of transverse reinforcement in the construction sequence also varies. Regions differ on whether the transverse reinforcement is installed and stressed  before or after the joint material is placed. The PCI Northeast Region Technical Committee (PCINE) recommends stressing the transverse reinforcement after the grout is placed for a square structure, but prior to grout placement for skewed bridges (see Appendix B). 5.2.1 Shear Keys

Shear keys consist of blockouts on the faces of adjoining elements of adjacent members as shown in Figures 3.1, 4.1, 4.2 and 4.4. After the members are in place on the structure, the joints are filled with mortar grout, epoxy or concrete, linking the adjacent members together. Shear keys are used in combination with transverse reinforcement or composite slabs by some agencies. Current practice indicates the

most effective systems utilize an epoxy grout or non-metallic, non-shrink grout in shear keys which extend the full length of the box beam.

Figure 5.1 Partial Depth Shear Key for Box Beams, Solid and Voided Slab Beams

The size, shape and location of shear keys vary widely. Locating the joints near the top of the member facilitates filling the blockouts. Deck bulb-tee sections and other  sections with a top flange have relatively small, narrow shear keys that are usually filled with a non-shrink grout. Box beams may use partial depth shear keys located near the top of section (Figure 5.1), but other details take advantage of the large contact area between adjacent boxes to utilize a longer, nearly full depth, but narrow shear key (Figure 5.2). Improved results have been reported with systems utilizing full depth shear keys instead of smaller keys. Some agencies have developed a simple  box girder system that utilizes standard AASHTO I-girder shapes to form the sides of  a box girder. The forms are placed far enough apart that a void is placed in the middle

creating a box shape with a large shear key formed by the abutting “I” shaped sides (Figure 5.3).

Figure 5.2 Full Depth Shear Key for Box Beams

Figure 5.3 Large Width Shear Key for Box Beams The most common material used to fill precast joints in adjacent member bridges is a non-shrink cement grout. However, epoxy grout is also used for the small shear keys and conventional deck concrete is commonly allowed to flow into the large shear key shown in Figure 5.3. Proper grout quality and grouting procedures have been found to be critical to the long term performance of the joints. Thoroughly cleaning the blockouts forming the  joints by pressure washing, then wetting the surface of the blockout prior to grout  placement improves the bond between the adjacent member and grout. Materials and grouting practices are generally based on regional preferences. Some regions report the most effective systems utilize shear keys in combination with a transverse reinforcing system to tie adjacent members together. 5.2.2 Welded Connections

Welded connections between adjacent precast members are constructed by casting weld plates and blockouts into the edges of the adjacent elements at several locations along the length of the member. After the components are erected, the plates are field welded to each other, typically using a filler plate (Figure 5.4) or rod (Figure 5.5), to make the connection between members. Various details have been used to allow for  construction tolerances both in the precasting process and erection. One agency noted that welding can be difficult when differential camber occurs.

Figure 5.4 Welded Attachment with Plate and Grouted Shear Key

Figure 5.5 Welded Attachment with Rod and Grouted Shear Key

5.2.3 Transverse Reinforcement

Transverse reinforcement installed after the adjacent members are in place affects the  performance of the joints. The reinforcement passes through the adjacent members,

locking them together during loading. The reinforcement may be post-tensioned. Mild, non-prestressed reinforcement is usually placed continuously along the length of the members, either in a composite slab, or across a closure pour. Post-tensioned reinforcing is generally installed at discrete locations along the member length. The number of locations, type of reinforcement (bars or strands of varying strengths) and amount of prestressing force applied ranges widely. Transverse post-tensioning reinforcement can be installed before or after the grout has been placed in shear keys. Skewed bridge construction brings another set of varying details. Many states try to avoid use of skewed bridges when feasible. Adjacent member bridges with transverse  post-tensioning have been constructed with the post-tensioned reinforcement placed  perpendicular to the beams across the full width of the bridge (Figure 5.6), placed full width across the bridge along the skew (Figure 5.7) and placed perpendicular to the  beams and staggered to connect only two adjacent girders per post-tensioning location (Figure 5.8). Post-tensioned ties are typically installed in sleeves cast in intermediate diaphragms, where the loading can be distributed throughout the system. Some agencies have found that installing skewed, transverse post-tensioning in  bridges with large skew angles can cause the box girders to slide longitudinally past each other, causing the girders to “rack”. See Appendix A.4 for a case study on how this problem was addressed for one railroad bridge. Other agencies have reported a tendency for skewed beams to “walk” and separate when not adequately tied together  with a tension tie.

Figure 5.6 Skewed Bridge - Square Post-tensioning

Figure 5.7 Skewed Bridge - Skewed Post-tensioning

Figure 5.8 Skewed Bridge - Staggered Posttensioning

5.2.4 Current Practice

Currently twenty-eight agencies use shear keys between adjacent members. Of these, seventeen report the use of keyways that differ in size or shape from those found on the standard AASHTO box beams. Thirteen agencies require that the shear keys be sandblasted. Sandblasting is performed at the precast plant in eight jurisdictions, while four require sandblasting at the job site; two prior to erection of the beams and two after girders are placed. Transverse post-tensioning is used in combination with shear keys by twenty agencies. Of these, eight report that post-tensioning is performed before the shear  keys are grouted, nine reverse the order of these operations and one agency varies the order dependent upon the skew angle of the bridge. The type of transverse  post-tensioning also varies, with twelve agencies reporting the use of strands, eleven using bars (some agencies use both). The strands are typically 0.5 inch strands, but the bars vary widely in both size and yield strength, from 1.5 inch, 36 ksi bars to #7  bars, 150 ksi. The post-tensioning bars are usually installed mid-depth of the beams or below, but some agencies utilize post-tensioning near the top of the beam. The number of post-tensioning locations along the girder generally increases with the length of the girder with post-tensioning typically applied every 25 to 30 feet. Some agencies define skew angle limits for the use of square, skewed or staggered transverse post-tensioning. 5.3 Design

Typically, a detailed design for shear or flexure in the joints is not performed. In most cases, standard details based on regional preferences are used without calculating  joint design loads. A general overview of design code requirements is given below.

5.3.1 AASHTO Standard Specifications for Highway Bridges (2002)

Specific guidelines were not provided for designing or detailing the longitudinal  joints. The specification does stipulate that a continuous longitudinal shear key and transverse tie reinforcement be provided to use the live load distribution factor  equations for multi-beam decks. Transverse tie reinforcement may or may not be  prestressed. Since the Standard Specifications are currently being phased out of use, this information is included here for historical reference only. 5.3.2 AASHTO LRFD Bridge Design Specifications (2004)

The specifications provide requirements for both the depth of the joint, or shear key, and minimum compressive strength of the non-shrink grout used to fill the joint. Based on the specific design method and detailing requirements used, the joints can either be considered “Shear Transfer Joints” or “Shear-Flexure Transfer Joints.” Meeting the more stringent design requirements of the latter allows for an improved live load distribution. Additionally, the specifications require the adjacent members  be prestressed transversely. The amount of transverse prestressing required must be determined by the strip method or a two-dimensional analysis, and meet minimum requirements for compressive force across the joint. Both El-Remaily et al. (1996) and Bakht et al. (1983) provide guidance and examples for the two-dimensional design of adjacent box beam bridges.

6. Continuity Adjacent member bridges can be made continuous for live load and other  superimposed dead loads by connecting the precast simple span members over  interior supports. This requires a negative moment connection over the support which typically consists of a cast-in-place concrete diaphragm and composite deck. Providing continuity decreases the positive design moments allowing for longer span lengths. Continuity also removes expansion joints over interior supports that can require significant long term maintenance. Many transportation departments design and construct bridges using this practice. However, there are important aspects of continuous bridges that need consideration.  NCHRP Report 519 (2004), “Connection of Simple-Span Precast Concrete Girders for Continuity,” provides recommendations for design and construction for this type of bridge. Significant conclusions from this report include the following: Due to the time dependent behavior of the prestressed concrete beams, positive moments can form at interior supports. Proper detailing of positive moment connections at these supports is important. Temperature effects on the beam/deck slab system can be significant. Current analytical models show that differential shrinkage between the deck slab and the girders can cause negative moments in the system. The presence of positive moment cracks at the connection does not affect the negative moment capacity of the system. A link slab system (Caner and Zia 1998) can be used as an alternative to a continuous for live load superstructure while still maintaining a jointless deck. In a link slab system, the continuous deck at interior supports is designed to allow the beams in adjacent spans to act as simple spans for all loadings. The deck is designed to withstand beam end rotations over the pier. This system has the added advantage of  allowing for the use of state DOT standard beam tables typically based on simple spans.

7. Bearings 7.1 General

Bearings for precast prestressed adjacent member bridges typically consist of  neoprene pads. Plain pads are typically used for shorter spans, with laminated neoprene pads for longer and heavier girders. When used, laminate embedded in the  pads is typically steel. In box beam bridges, support configurations include 4-point support where bearing  pads are located under each corner of each box beam; continuous support, where  bearing pads are continuous under each end of each box beam; and 3-point support, where one bearing pad is located under each corner of the box at one end of the span, and a wider single pad is centered under the opposite end of the beam. Two single corner pads can be located side by side to form the single pad. The center pad and corner pad layout of the three-point system can also alternate end to end at adjacent girders to provide a more uniform overall bearing of the system. Lateral restraint is typically provided to minimize lateral movement at supports and secure the structural system to the substructure. Shear keys or blocks can be used to  provide lateral restraint in seismic and non-seismic regions.

7.2 Survey Questionnaire Response Summary

 Nearly all respondents reported using neoprene pads for the support of box beam superstructures. Only three of thirty-one respondents did not use neoprene pads, with two using fabric pads, and one using 0.5 inch preformed joint filler. The largest variation for the neoprene pad users was related to the use of plain or laminated pads. Seven agencies reported using only plain pads, fourteen use only laminated pads, and eight use either plain or laminated pads, depending on the design requirements. Fourteen respondents indicated uneven seating of the box beams has occurred. Skewed ends and variations in box geometry can cause the uneven seating, and in some cases, rocking of the boxes during construction. Several states have recently switched to a 3-point bearing system (Figure 7.1), particularly on skewed bridges, in an attempt to minimize these conditions. Primary concerns with the uneven seating include problems with alignment and grouting during construction, and excess  bearing pressure. Some form of lateral restraint is required by most agencies. Eighteen report the use of  dowel pins, typically steel, for lateral restraint. Five use blocks or shear keys, and four  agencies utilize either dowel pins or shear keys. Three agencies consider the embedment of reinforcing steel into integral concrete diaphragms as sufficient for  lateral restraint. Only one respondent reported using no lateral restraint other than shear stiffness of the bearing pads.

Figure 7.1 Plan View of Three Point Bearing System (TxDOT)

7.3 Railroad Structures

Bearing pads utilized for railroad double-cell box beams typically consist of 0.75 inch urethane pads, continuous under the ends of the beams. Heavier single-cell boxes are supported on laminated neoprene pads, continuous under the ends of the beams. Design of bearings for railroad structures is based on procedures outlined in the American Railway Engineering and Maintenance of Way (AREMA) Manual for  Railway Engineering.

8. Maintenance Issues 8.1 General

Early design and construction practices have created serviceability problems with box girder bridges. The predominant distress observed in adjacent box girder bridges is reflective cracking of the deck along the shear keys between beams (Figure 8.1) and the associated degradation of the box beams below the reflective cracks (Figure 8.2). The reflective cracking constitutes a serious problem, as it allows penetration of  surface water and deicing chemicals through the deck and between the beams. Reflective cracking occurs more readily on bridges utilizing asphalt wearing surfaces, although the problem also occurs on bridges with concrete deck surfaces. Deterioration of individual box beams and the related structural system comes in many forms. Visual symptoms usually consist of cracks and/or spalls. These areas are of concern because they may allow salt-laden water to penetrate into the structural member and cause further deterioration of the concrete, prestressing strands and reinforcing steel. Deterioration of transverse tensioning elements and substructure units may also occur.

Figure 8.1 Reflective Deck Cracking Along Shear Keys Between Beams

Figure 8.2 Degradation of Box Beams Below Reflective Cracking

8.2 Inspection

Proper identification, diagnosis and timely maintenance are essential to preserve adjacent member bridges. As load ratings are affected by the current condition of the  bridge, it is important to recognize and document the forms of distress and their  locations while conducting inspections. Bridge inspections should, as a minimum, identify size and depth of cracks, areas of  spalling, extent of delaminated concrete, exposed reinforcement and prestressing

strands, section loss, evidence of water staining, efflorescence and corrosion, and condition of the various structural elements. Spalling on the exterior face of an exterior box girder with exposed prestressing strands is shown in Figure 8.3.

Figure 8.3 Spalling on Exterior Face of Box Girder  Corrosion of the prestressing strands greatly impacts the capacity of the structure, not only because it causes a loss of a key component in a prestressed system, but corroding steel may also expand three to six times the original volume and cause further loss of concrete section due to cracking and spalling (Teng 2000). A Michigan DOT (MDOT), Michigan Tech and Wayne State Universities project, “Condition Assessment and Methods of Abatement of Prestressed Concrete BoxBeam Deterioration”, (MDOT 2007) describes thirteen types of common degradation specific to prestressed box beams. These are reprinted in the “Prestressed Box-Beam Assessment Handbook.” This handbook developed for prestressed box-beam assessment has been designed to serve as a supplement to the Pontis Bridge Inspection Manual (MDOT 1999), and should serve as a guide to aid bridge inspectors and engineers while assessing the condition of box-beams for the purpose of scoping or damage evaluation inspections. The level of detail called for in the assessment handbook may be greater than needed for routine biennial inspections. 8.3 Load Ratings

Bridge load ratings are used by bridge owners to assess the structural integrity of their   bridges, and are reported to the Federal Highway Administration in the form of the  National Bridge Inventory (NBI). Damage and deterioration of the structural

members of the bridge are incorporated into the load rating, and structural repairs may be required if a load rating falls below accepted standards. Load rating a prestressed concrete box-beam requires six conditions for the inventory rating and three conditions for the operating rating. Each rating requires a strength check of the member, both flexural and shear, and a service limit check. The inventory rating requires a service level check of concrete tension, concrete compression, and prestressing steel tension. The operating rating only requires that the prestressing steel tension be checked. Four properties are directly influenced by deterioration: compressive strength of the concrete, moment of inertia, cross-sectional area of the beam, and the cross-sectional area of the prestressing steel. The compressive strength of the concrete is the only  property directly related to material related distress. The cross-sectional area of the  beam, moment of inertia, and total area of prestressing strand are all related to the  physical condition of the box beam. Changes to the cross-section of the beam also result in different values for centroid and eccentricity of the prestressing strands. All of these components must be updated to reflect the capacity of a beam in a distressed state. These properties are used directly in the calculation of the service level stresses for both the inventory and operating ratings, and are used by the strength ratings to determine the moment and shear capacity of the beam. Parameters such as applied loads do not need to be reassessed unless the location or  type of deterioration indicates that load patterns may change. For example, if load transfer mechanism deterioration lessens the load sharing capabilities of the adjacent  box beam design, the load distribution will be influenced. If this type of deterioration has occurred, it may be necessary to revise the distribution factors for live and dead loads to reflect the current condition of the bridge.

9. Survey of Current Practice 9.1 Introduction

To obtain current information on the use of box beam bridges, the Subcommittee on Adjacent Member Bridges distributed a questionnaire to the departments of  transportation in all fifty states and to the ministries of transportation in thirteen Canadian provinces. In addition, the survey was sent to nine additional agencies or  entities. The questionnaire solicited specific information in the following general categories: 1. Organization’s experience with box beam bridges 2. Deck slab and overlays 3. Box beam construction 4. Keyways 5. Prestressing 6. Bearings 7. Lessons learned The questionnaire also requested drawings and photographs of representative box  beam bridges. The response was good, with forty five of the fifty states, three of the thirteen Canadian provinces, plus the New Jersey Turnpike Authority and Prestress Engineering Corp. responding to the questionnaire. 9.2 Data Collection/Survey Response

The effort for this report began by developing a questionnaire. The first question asked was whether or not the responding entity used box beam bridges. If the answer  was negative, further response was not required. If the answer was affirmative, information in the above-mentioned areas was collected. A wide variety of responses to the various box beam related questions were submitted. Box beams are currently used in twenty nine of the forty five states and the three Canadian provinces which responded to the questionnaire. Based on the information available, the matrix shown in Appendix C was prepared to summarize the survey responses.

9.3 Lessons Learned

A number of important lessons were reported by the respondents: Many respondents discussed the importance of minimizing longitudinal cracking to  prevent water penetration into the longitudinal joints. Surveys of adjacent box beam  bridges made in the late 1980s and early 1990s revealed that reflective cracks in the wearing surface were a recurring problem in some areas. These cracks should be  prevented because water and deicing chemicals may penetrate the cracks and cause concrete staining and eventual structural deterioration. One state reported many detail changes over the last twenty years that considerably improved performance and reduced water leakage between adjacent boxes. These included placing the bearing pads under the edge of the beam rather than under the middle to prevent rocking of the beams during grouting of the shear keys, blast cleaning the key surfaces, the use of non-shrink grout instead of sand/cement mortar  in the keys, and the use of corrosion inhibitor in the concrete mix for the box beam. The combined use of sufficient transverse connections, non-shrink grout or  appropriate sealant in the keyways, and a composite deck slab provides a reasonable assurance against longitudinal deck cracking. The use of a cast-in place composite slab can prevent leakage between box beams. Transverse tie post-tensioning helps control differential deflection in adjacent box or  slab construction. Two states report that reflective cracking and associated leakage have been eliminated with the use of the full depth shear key developed by the PCINE Technical Committee. One state is considering eliminating the use of welded connections between adjacent  boxes due to longitudinal cracking associated with this detail. This is the only state that reported using welded connections between boxes. Lack of adequate positive transverse tie force is the primary cause of shear key failure. Dimensional tolerances in tall box sections may create gaps which are difficult to seal, allowing grout to drip through the longitudinal joints during grouting of  keyways. Inadequate sealing has presented problems when used over traveled roadways. To provide a more uniform overlay thickness, one Canadian province varies the top flange thickness to offset upward beam camber.

Two states report instances of poor seating for some box beams embedded into CIP diaphragms. However, these have not resulted in any actual in-service distress. Jointless bridges are the best way to avoid problems with bearings and substructure corrosion. One state expressed concern that concrete cover within the box may not be provided,  but no inspection process is available for checking. Sloping the bearing seats to match the cross slope helps with seating the boxes. One state limits the use of box beams to small bridges with spans of 40 feet or less. Minimize skews where practical. Provide lateral restraint at piers and abutments. Utilize polystyrene material for form voids. Cardboard forms may react with concrete, creating gases that can cause concrete to crack and split off.

10. Summary of Case Studies Five case studies appear in Appendix A representing the application of different adjacent member systems by various agencies. The following projects were included: 10.1 NASA Road 1 Bridge over I-45

The NASA Road Bridge 1 over I-45 is a Texas Department of Transportation project that replaced a 300 foot long, four span bridge over six lanes of the interstate mainline, and dual two lane frontage roads in just nine days. 10.2 Mitchell Gulch Bridge, Colorado

The reconstruction of the single span bridge carrying Colorado Highway 86 over  Mitchell Gulch was a value-engineered project that demonstrated how adjacent members can be used to greatly reduce the length of construction time, and to minimize inconvenience to the public on a heavily traveled road. 10.3 Quaker City Bridge, Ohio

The superstructure of this two span bridge was replaced with a precast, adjacent member superstructure, reusing the existing intermediate pier and abutments. The  project uses laterally post-tensioned, precast reinforced concrete slab beams. 10.4 BNSF Railway over Route 160, Missouri

The BNSF Railway Bridge over Missouri Route 160 is a grade separation structure in Springfield, Missouri. This 158 foot long, triple track, three span structure replaced two existing structures that did not provide sufficient horizontal clearance to widen Route 160 beneath. An intricate staging sequence and a temporary shoofly structure was constructed in conjunction with the replacement bridges to maintain a minimum of two sets of tracks in service at all times during construction. 10.5 Route 100 over I-44, Missouri

The Missouri Route 100 Bridge over I-44 is a two span overpass near Gray Summit, Missouri, just west of Saint Louis. The replacement structure was value-engineered from a four span rolled beam bridge to a two span, adjacent box girder bridge after  contractors encountered cost penalties from the steel industry associated with the rapid construction schedule.

11. Summary of Current Research 11.1 UHPC

The FHWA is investigating ultra high performance concrete (UHPC) for use in  bridge design utilizing an optimized bulb-double-tee shape (Graybeal and Hartman, 2005). Figure 11.1 provides the cross-section. Two girders using these sections were erected side by side to form an adjacent member bridge at the FHWA TurnerFairbank Highway Research Center. Testing on these members to determine the elastic lateral load distribution of the members has been performed (Graybeal and Hartman, 2005(2)).

Figure 11.1 FHWA Pi Girder Test Section

Buchanan County, Iowa, with the assistance of the Iowa DOT and Iowa State University, is the site of the first bridge in the U.S. built with Pi-shaped girders made of ultra high performance concrete. The Bridge Engineering Center staff of Iowa State University is assessing the behavior of the individual elements during construction as well as their long-term performance and overall behavior of the completed bridge. Based on results of testing by FHWA, changes are being made to the optimized Pi section shown above, including thicker webs, thicker deck and consideration of  transverse tensioning.

11.2 NCHRP Projects

Other NCHRP research projects directly or indirectly related to adjacent members include: 10-71

Evaluation of CIP Reinforced Joints for Full-Depth Precast Concrete Bridge Decks

10-72

Bridge Deck Design Criteria and Testing Procedures

10-73

Guide Specification for the Design of Externally Bonded FRP Systems for  Repair and Strengthening of Concrete Bridge Elements

12-56

Application of the LRFD Bridge Design Specifications to High-Strength Structural Concrete: Shear Provisions

12-57

Extending Span Ranges of Precast, Prestressed Concrete Girders

12-58

Effective Slab Width for Composite Steel Bridge Members

12-60

Transfer, Development, and Splice Length for Strand/Reinforcement in High-Strength Concrete

12-62A Simplified Live Load Distribution-Factor Equations-Phase II 12-64

Application of the LRFD Bridge Design Specifications to High-Strength Structural Concrete: Flexure and Compression Provisions

12-65

Full-Depth, Precast-Concrete Bridge Deck Panel Systems

12-68

Improved Rotational Limits of Elastomeric Bearings

12-69

Design and Construction Guidelines for Long-Span Decked Precast, Prestressed Concrete Girder Bridges

12-71

Design Specifications and Commentary for Horizontally Curved Concrete Box-Girder Highway Bridges

12-72

Blast-Resistant Highway Bridges: Design and Detailing Guidelines

12-73

Design Guidelines for Durability of Bonded CFRP Repair/Strengthening of  Concrete Beams

12-74

Development of Precast Bent Cap Systems for Seismic Regions

12-75

Design of FRP Systems for Strengthening Concrete Girders in Shear 

12-77

Structural Concrete Design with High-Strength Steel Reinforcement

12-80

LRFD Minimum Flexural Reinforcement Requirements

12-83

Calibration of LRFD Serviceability

18-12

Self-Consolidating Concrete for Precast, Prestressed Concrete Bridge Elements

18-14

Evaluation and Repair Procedures for Precast/Prestressed Concrete Girders with Longitudinal Cracking in the Web

18-15

High-Performance/High-Strength High-Performance/High-Strength Lightweight Concrete for Bridge Girders and Decks

20-5

Synthesis Topic 39-10, Adjacent Precast Box Beam Bridges: Connection Details

Concrete Concrete

Bridge Design

Specifications Specifications

for  for 

12. Conclusions 12.1 General

This report presents the state-of-the-art on precast, prestressed adjacent box beam  bridges. Although early construction practices may have lead to serviceability issues with box girder bridges, improved practices have made the box girder bridge a viable, cost-effective structural system. Adjacent box beam bridges have many advantages over other bridge types in speed and ease of construction, aesthetics, span to depth ratio and cost. Lessons learned have been many, and indicate the importance of   proper design, fabrication and construction to the effective performance of the integral structural system. For maximum structural performance, all important components should be incorporated into the box girder system. Design, fabrication and construction practices that have been shown to improve the performance of  adjacent box girder systems are summarized below. What follows are conclusions drawn from the survey. 12.2 Design

Utilize high performance or high strength, low permeability concrete in the beams and deck slab. Provide shear key geometries that allow deck concrete to fill the key, or use full depth shear keys. Provide a minimum of 1 ½ in. cover to all reinforcing. Use 2 in. where practical. Utilize strand patterns which omit use of prestressing strands in the exterior corners. Design for composite action with a reinforced concrete deck slab (minimum thickness of 5 in.). Minimize skews where practical. Provide lateral restraint at piers and abutments. Consider 3-point bearing system to minimize rocking of girders. Utilize corrosion inhibitor in the concrete mix design for the beams. Provide waterproofing between top of structural member and overlay if a noncomposite overlay is to be used.

12.3 Fabrication

Utilize polystyrene material for form voids. Provide consistent casting conditions to minimize differential camber in beams. Properly anchor void forms to prevent floating of forms during casting. Provide vent holes for beam curing, in addition to drainage holes in boxes. When extending stirrups for shear connection to slab, consider bent shape of bar in relation to placement of void forms. When extending mild reinforcing steel at the ends of beams, provide straight bars and  bend after fabrication.

12.4 Construction

Provide transverse post-tensioning to compress joints and minimize differential deflections between boxes. Sandblast shear keys prior to grouting or concreting. When using small shear keys, utilize epoxy grout in keyways. Some agencies report success with non-metallic, non-shrink grout. Post-tension transverse ties prior to grouting shear keys on skewed bridges, after  grouting on square bridges. Grind concrete pier and abutment surfaces if necessary to achieve uniform bearing surface. Offset longitudinal deck joints a minimum of 1 foot from edge of adjacent box in staged construction. When differential camber occurs, force beams together when practical or provide smooth transition with joint grout material.

13. References Chapter 5

1. El-Remaily, Ahmed, Tadros, Maher, Yamane, Takashi, and Krause, Gary “Transverse Design of Adjacent Precast Prestressed Concrete Box Girder Bridges”, PCI Journal, 41(4), July/August 1996. 2. Bakht, Baidar, Jaeger, Leslie, and Cheung, M.S., “Transverse Shear in Multibeam Bridges”,  ASCE Journal of Structural Engineering , 109(4), April 1983. 3. AASHTO, LRFD Bridge Design Specifications, 3rd Edition, American Association of State Highway and Transportation Officials, Washington, D.C., (2004). 4. AASHTO, Standard Specifications for Highway Bridges, 17th Edition, American Association of State Highway and Transportation Officials, Washington, D.C., (2002).

Chapter 6

1. Miller, Richard, Castrodale, Reid, Mirmiran, Amir, and Hastak, Makarand, “Connection of Simple-Span Precast Concrete Girders for  Continuity”, NCHRP Report 519, Transportation Research Board, Washington, D.C., 2004. 2. Caner, Alp, and Zia, Paul, “Behavior and Design of Link Slabs for  Jointless Bridge Decks,” PCI Journal , 43(3), May/June 1998. Chapter 8

1. AASHTO. (2003). Interim Revisions to the Manual for Condition Evaluation of Bridges, Second Edition. American Association of State Highway and Transportation Officials, Washington DC. 2. MDOT (2007) Condition Assessment and Methods of Abatement of  Prestressed Concrete Box-Beam Deterioration – Phase I. Michigan Department of Transportation, Report # RC-1470. 3. MDOT. (1999). Pontis Bridge Inspection Manual. Michigan Department of Transportation, Lansing Maintenance Division, Lansing MI.

4. Miller, R.A., Hlavacs, G.M., and Long, T.W. (1998). “Testing of Full Scale Prestressed Beams to Evaluate Shear Key Performance.” FHWA report # OH-98/019, Federal Highway Administration. FHWA report # OH-98/019 5. Teng, T. P. (2000). “Materials and Methods for Corrosion Control of  Reinforced and Prestressed Concrete Structures in New Construction.” FHWA-RD-00-081. Federal Highway Administration. Chapter 12 1. Graybeal, B. and Hartmann, J., (2005), “Experimental Testing of  UHPC Optimized Bridge Girders: Early Results,” Proceedings of the PCI National Bridge Conference, Palm Springs, CA, October 16-19.

2. Graybeal, B. and Hartmann, J., (2005(2)), “Lateral Load Distribution in Optimized UHPC Bridge Girders,” Proceedings of the International Conference on Advanced Materials for Construction of Bridges, Buildings and Other Structures, IV, Maui, Hawaii, August. 3. Miller, Richard, Castrodale, Reid, Mirmiran, Amir, and Hastak, Makarand, (2004), “Connection of Simple-Span Precast Concrete Girders for Continuity”, NCHRP Report 519, Transportation Research Board, Washington, D.C.

14. Bibliography AASHTO LRFD Bridge Design Specification (2005), 3 rd ed., American Association of Highway and Transportation Officials, Washington, D.C. AASHTO Standard Specifications, (2002), 17 th ed. American Association of  Highway and Transportation Officials, Washington, D.C. Bakht, B., Jaeger, L., and Cheung, M., (1983), “Transverse Shear in Multi-beam Bridges,” Journal of Structural Engineering, ASCE, v. 109, n. 4, April, pp. 936-949. El-Remaily, A., Tadros, M., Yamane, T., and Krause, G., (1996), “Transverse Design of Adjacent Precast Prestressed Concrete Box Girder Bridges,” PCI Journal v. 41, n. 4, July-August, p. 96-113. Grace, N., Enomoto, S., Sachidanandan, S., and Puravankara, S., (2006), “Use of  CFRP/CFCC Reinforcement in Prestressed Concrete Box Beam Bridges,” ACI Structural Journal, v. 103, n. 1, p. 123-132. Gulyas, R., Wirthlin, G., and Champa, J., (1995), “Evaluation of Keyway Grout Test Methods for Precast Concrete Bridges,” PCI Journal v. 40, n. 1, p. 44-57. Hlavacs, G., Long, T., Miller, R., and Baseheart, T., (1997), “Nondestructive Determination of Response of Shear Keys to Environmental and Structural Cyclic Loading,” Transportation Research Record, n. 1574, pp. 18-24. Huckelbridge, A., El-Esnawi, H., and Moses, F., (1995), “Shear Key Performance in Multi-Beam Box Girder Bridges,” Journal of Performance of Constructed Facilities, v. 9, n. 4, p. 271-285. Lall, J., Alampalli, S., and DiCocco, E., (1998), “Performance of Full Depth Shear  Keys in Adjacent Prestressed Box Beam Bridges,” PCI Journal, v. 43, n. 2, MarchApril, pp. 72-79. Martin, L., and Osborn, A., (1983), “Connections for Modular Concrete Bridge Decks,” FHWA-82/106, NTIS Document PB84-118058, Consulting Engineers Group, Glenview, IL, August. Miller, R., and Parekh, K., (1994), “Destructive Testing of a Deteriorated Prestressed Box Beam Bridge,” Transportation Research Record, n. 1460, pp. 37-44. Miller, R., Hlavacs, G., Long, T., and Greuel, A., (1999), “Full-Scale Testing of  Shear Keys for Adjacent Box Girder Bridges,” PCI Journal v. 44, n. 6, p. 80-90.

 Nottingham, D., (1995) Discussion of “Evaluation of Keyway Grout Test Methods for Precast Concrete Bridges,” by Gulyas, R., Wirthlin, G., and Champa, J., (1995), PCI Journal v. 40, n. 4, p. 98-103. Osborn, A., and Preston, H., (1990), “Post-Tensioned Repair and Field Testing of a Prestressed Concrete Box Beam Bridge,” ACI SP-120, p. 229-256. Precast Prestressed Concrete Bridge Design Manual, (1997), PCI, Chicago, IL. Stanton, J., and Mattock, A., (1986), “Load Distribution and Connection Design for  Precast Stemmed Multibeam Bridge Superstructures,” NCHRP Report 287, Transportation Research Board, Washington, D.C. Yamane, T., Tadros, M., and Arumugasaamy, P., (1994), “Short to Medium Span Precast Prestressed Concrete Bridges in Japan,” PCI Journal, v. 39, n. 2, March-April,  pp. 74-100.

Appendix A: Case Studies Five examples of adjacent member bridges are discussed in this section: A.1

NASA Road 1 Bridge over I-45, Texas - 2002

A.2

Mitchell Gulch Bridge, Colorado - 2002

A.3

Quaker City Bridge, Ohio - 2003

A.4

BNSF Railway over Route 160, Missouri - 2002

A.5

Route 100 over I-44, Missouri - 2006

A.1 - NASA Road Bridge 1 over I-45, Texas

Figure A.1.1: NASA Road 1 Bridge Elevation

At the NASA Road 1 Bridge over I-45 between Houston and Galveston, the Texas Department of Transportation (TxDOT) makes use of a unique adjacent member system that eliminates the necessity of either grouting or post-tensioning operations to connect the adjacent girders. This structure is one of a pair of parallel bridges that carries four lanes of traffic over I-45; the other  structure is a traditional steel girder bridge. The 300 foot long bridge crosses three lanes of I-45 and a two lane frontage road in each direction with four equal spans of 75 feet (Figure A.1.1), replacing a six span structure with one that matches the span layout of the eastbound bridge. The NASA Road 1 overpass was designed in accordance with the 1996 AASHTO Standard Specification for Highway Bridges for HS-20 Live Loading. The bridge crosses I-45 on a square alignment and has a broad vertical curve centered on the bridge. Precast concrete was used for   both the superstructure and substructure as part of an accelerated construction scheme. The abutments and piers are supported on five 24 inch square precast, prestressed piles, which vary from 49 to 76 feet in length, and from 105 tons to 135 tons in capacity. The abutment wingwalls, caps and intermediate bent caps were also designed with a precast option, however the C.I.P. alternate was chosen. The precast abutment and intermediate bent caps were cast with the tops sloped to match the 2.08% roadway cross slope. This places the boxes slightly out of square; however this did not  present any problem for the torsionally stiff boxes. In the past, TxDOT had experienced  problems with box girders rocking transversely when supported on bearings at each corner. To alleviate this problem, box girders are now supported on a 3-point bearing system consisting of 

two smaller bearings placed near the corners at one end of the girder and a single, wider bearing located at the centerline of the girder at the opposite end (Figure A.1.2). The box beams are restrained transversely by concrete ears that are cast on each end of the caps. The abutment caps also have a backwall to provide longitudinal restraint.

Figure A.1.2: Bearing Pad Layout

The 75 foot spans of this structure are supported by nine, adjacent TxDOT Type 4B28 girders (Figure A.1.3). These 28 inch deep precast beams are formed by using two side forms from Texas “Type A” Standard Prestressed Concrete Beams that are spaced approximately four feet apart. Concrete is poured around a styrofoam block placed between the side forms that creates

Figure A.1.3: Bridge Cross Section

the void for the box beam (Figure A.1.4). The box girders are prestressed with 24 straight, ½ in. diameter, 270 ksi lowrelaxation strands located in the bottom flange. A vertical, 1½ in. diameter  PVC pipe is cast in the  bottom slab of the box  beam at each corner to  provide drainage for any water that might accumulate inside the void. A 7 in. deep, 12 in. long blockout is also  provided at each end of  the girders. Reinforcing  bars are placed in this void and it is filled with concrete from the slab  pour to create an end Figure A.1.4: Typical Section of Box Beam diaphragm (Figure A.1.5). A plastic joint former is located in the slab over the piers between the end diaphragms to create a control joint and silicone sealant is used to fill the 1 in. gap between the end diaphragm at the abutments and the approach pavement.

Figure A.1.5: Detail of Shear Key and End Diaphragm

After the adjacent box girders are placed, a 5 in. thick, reinforced, cast-in-place slab is  poured on top. The ordinary slab concrete in this pour is also allowed to flow into the large shear key  provided by the “I” shaped sides of the adjacent box girders (Figure A1.5). A chamfer strip is  placed in the gap  between the box girders to retain the concrete in the shear 

key (Figure A.1.6). “U” shaped reinforcing bars at 12 in. spaces extend from the top slab of the girders into the slab to insure composite action of the slab and box beams. The exterior girders also have “U” shaped bars embedded near the outside edge that project through the slab and into the barrier curb, which is poured on top of the slab. Bridges that utilize an asphalt driving surface have posttensioning bars located in internal diaphragms; however TxDOT does not require interior diaphragms for adjacent  box beam bridges that utilize a cast in  place slab. Summary Discussion Through their use of box beams since the 1960s, TxDOT has encountered and solved several issues. The concrete in the  box beams is required to be placed in a two-stage monolithic pour. Fabricators had experienced difficulties holding the void Figure A.1.6: Detail of Plug forms in place; the void forms would try to shift laterally when concrete is placed unequally on the two sides of the box, and would be forced upwards by buoyancy when the  bottom and both sides were placed. Attempts to prevent the lateral movement of the void form  by filling both sides of the box equally resulted in air voids in the concrete of the bottom slab. To avoid these problems, TxDOT specifies that the concrete in the bottom slab be placed first, and remain in the plastic state until the concrete in the second stage, the walls, is placed. In the past cardboard forms had been used to create the void; however TxDOT had found that this could lead to problems when a reaction between the cardboard and the concrete created gases that would cause the bottom flange of the boxes to split off.

The use of this simple adjacent member superstructure system allowed TxDOT to completely reconstruct the NASA Road 1 Bridge in just nine days, greatly minimizing the disturbance to the traveling public.

A.2 - Mitchell Gulch Bridge, Colorado

Figure A.2.1: Colorado State Route 86 Mitchell Gulch Bridge

The reconstruction of the bridge carrying Colorado Highway 86 over Mitchell Gulch (Figure A.2.1) illustrates how adjacent girders can be part of a rapid construction solution to drastically reduce construction delays typically associated with bridge construction projects. This bridge replacement project was completed over one weekend with a total road closure of only 46 hours. The Mitchell Gulch Bridge project originally was designed as a typical bridge replacement  project with an anticipated two month road closure and detour required to construct a cast-in place box culvert on the same alignment as the aging wooden bridge it was to replace. After the original design was bid, the winning bidder submitted a value engineering proposal to drastically reduce the inconvenience to the approximately 12,000 daily vehicle drivers that travel this stretch of Highway 86, just southeast of Denver. This proposal significantly compressed the construction schedule for a total cost of $360,000, approximately the same as the original winning bid.

The new single span bridge carrying Highway 86 spans 35 ft over Mitchell Gulch is on a square alignment (Figure A.2.2). The bridge was designed in accordance with the AASHTO 16 th Edition Load Factor Design Manual for HS-25 Live Loading and a future overlay of 36 psf. The structure makes significant use of precast elements for both superstructure and substructure. Precast abutment backwalls and wingwalls were welded to steel H-piles that were placed outside of the existing bridge and roadway. This arrangement allowed piling to be pre-driven  prior to the road closure. The 44 ft long backwalls are split into an upper and lower section and each 24 ft long wingwall is a separate piece. Embedded weld  plates were cast into each of the elements to allow welded connections to the pile supports and other elements. After the abutments were constructed, they were backfilled with flowable fill. Figure A.2.2: Bridge Alignment The superstructure of the Mitchell Gulch Bridge is composed of eight adjacent, precast,  prestressed slab beam members. The 18 in. thick by 5 ft-4 in. wide beam slabs (Figure A.2.3)

Figure A.2.3: Section through slab beam

span 37 ft-4 in. from bearing to bearing to provide the 35 ft opening. Each girder contains 20 straight prestressing strands; 0.6 in. diameter with a total initial  prestress force of 820 kips. After  release the strands were cut 1 in. inside the surface of the concrete and the ends were patched with an epoxy grout. The girders are supported on a ½ in. by 6 in. continuous bearing pad and are held in place on the abutments by angles that are welded to embedded plates in the abutment  backwalls and girder ends (Figure A.2.4). The adjacent deck girders are laterally connected to each other   by 1¼ in. post-tensioning rods and a shear key as shown in Figure A.2.5. Four inch diameter PVC sleeves were placed at the ⅓ and ⅔  points of the span and the Figure A.2.4: Embedded weld plates at beam slab ends galvanized post-tensioning rods were placed through these ducts after the girders were placed. The rods were then post-tensioned to 10% of the final post-tensioning force of 131 kips per rod prior to the grouting of the shear keys with an epoxy grout capable of attaining a compressive strength of 3000 psi within 12 hours. After the grout had hardened sufficiently to  prevent spalling, the full 131 kip  post-tensioning force was applied. The contractor was allowed to weld the two interior girders to the abutments after just the initial 10%  post-tensioning force was applied, however the remaining girders were not to be welded until the Figure A.2.5: Longitudinal Shear key shear keys had been grouted and the full post-tensioning force applied.

The exterior girders have a 7½ in. square blockout on the exterior face for the post-tensioning hardware. The exterior girders also differ from the interior girders due to the 18 in. wide by 19¾ high curb that was cast on the slab beams in the plant after the girder was removed from the  precasting bed. Anchor bolts were cast in the curb to attach a traffic railing to the curb prior to the erection of the girders (Figure A.2.6).

Figure A.2.6: Exterior beam slab with integral curb and attached traffic rail

The laterally post-tensioned adjacent beam slab members function as the bridge deck as well as spanning longitudinally, eliminating the need for a cast-in-place slab. Eliminating slab forming,  pouring and curing from the critical path greatly reduced the construction time. The driving surface consists of 6¼ in. of asphalt placed over an aggregate base course. The curbs on the exterior girders also serve to retain the base course and pavement on the bridge. The girder   bearings at the abutment were level to facilitate the post-tensioning and alignment of the shear  keys, so it was necessary to taper the thickness of the base course to achieve the required 2% cross slope (Figure A.2.7). PVC pipes, 2 in. in diameter, are cast near each end of the girders and at midspan to function as drain holes for the base course material.

Figure A.2.7: Transverse section showing tapered subgrade material used to create cross slope Summary Discussion The Colorado Department of Transportation’s willingness to allow the use of a new bridge system paid large dividends. The adjacent precast members for the superstructure were combined with a precast substructure to facilitate the replacement of a highway bridge in less than two days, minimizing the impact on the traveling public. To achieve this rapid construction, thorough organization and contingency planning was required. As with most construction projects, there were some difficulties that arose during construction. One such problem occurred when the epoxy grouting process was begun before the transverse post-tensioning had been completed. The fast setting epoxy began to harden before the post-tensioning operation was complete which necessitated chipping out the epoxy and re-grouting the joints after the post-tensioning was completed.

The post-tensioned adjacent beam slab design added some complexity to construction process; however this system allowed several time consuming steps from typical bridge construction to be eliminated. Careful planning, the construction teams ability to react to issues and the use of an adjacent member superstructure all contributed to the success of this project.

A.3 - Quaker City Bridge, Ohio - Rapid Replacement Using Adjacent Post-tensioned Slabs

Figure A.3.1: Quaker City Bridge

GUE-513-1.80 located in the town of Quaker City, Ohio (approximately 50 miles east of  Columbus). The existing bridge was a 2 span, concrete slab bridge, with each span being approximately 30 foot long. The superstructure was to be replaced, but the existing pier and abutments were to be re-used after repair. Another slab bridge was the logical replacement structure but the time required to construct a slab bridge was a concern. Because the site is in a rural area, the detour was approximately 25 miles for cars and 40 miles for trucks and large  busses. Local officials were concerned about detouring school busses over this long distance and wanted the bridge built after the school year ended and with as little interference with the summer school term as possible. Another major factor in the decision to accelerate the construction was a festival held in Quaker City each summer. The festival is a major revenue source for the local community and it was desirable to have the bridge completed before the festival. As a result, the bridge had to be completed in less than 3 weeks. The engineer decided to use a post-tensioned, adjacent concrete slab unit for the superstructure. The rail would be precast concrete as well. Figures A.3.2 – A.3.5 show the details of the bridge structure. The slab panels used a full depth joint with a mid-height shear key (Figure A.3.6). After demolition of the old slab, the abutments and the center support were reworked to accommodate the precast slabs. The precast slabs were reinforced elements. They were not  pre-tensioned to simplify the fabrication and to avoid any camber problems.

To insure proper alignment of the PT ducts, a mock up assembly of the slabs was required in the  precasting yard. Unfortunately, no one thought to account for the crown in the bridge. When the slabs were delivered to site, there was some misalignment due to the crown which had to be fixed by shimming the supports. After the slabs were assembled, the joints were grouted. Grout was a major problem on this structure. The engineer had specified a high early strength, fast setting grout. The contractor did not pick this up in the bid phase and did not have an acceptable grout available. When the contractor attempted to purchase an acceptable grout, he could not find a grout which both met the engineer’s specifications and was on the Ohio DOT approved list. Eventually, the engineer  and the contractor found a grout acceptable to all parties. Grout placement was a problem as the grouting company was not familiar with grout. After post-tensioning, the grout cracked and the cracks were sealed with high molecular weight Methacrylate (HMWM). In a post construction meeting, both the contractor and ODOT acknowledged that grout is, in general, a problem in adjacent girder bridges. After grouting was complete, the bridge was post-tensioned in both the longitudinal and transverse directions. The longitudinal post-tensioning made the bridge continuous for live load. Three, 0.6 in diameter strands were used in each duct to post-tension the structure. After posttensioning, the ducts were grouted for corrosion protection (Figure A.3.7). To further reduce construction time, the bridge was precast with an integral wearing surface. After assembly of the  bridge, the surface was ground to profile and grooves were sawcut into the surface. A precast rail was used. The rail was post-tensioned to the fascia girder when the transverse post-tensioning was done. The bridge met expectations for speed of construction. Although originally scheduled for 16 day, unavoidable delays extended the construction time to 19 days; but this was well within acceptable limits.

Figure A.3.2: Elevation of the Replacement Structure

Figure A.3.3: Longitudinal Section of a Single Panel

Figure A.3.4: Longitudinal Section of the Deck 

Figure A.3.5: Cross Section of the Deck 

Figure A.3.6: Slab Placement - Longitudinal PT Ducts and Shear Keys Are Visible

Figure A.3.7: PT Tendons

A.4 - BNSF Railway over Route 160, Missouri

Figure A.4.1: Elevation at Project Baseline

The BNSF Railway Bridge over Missouri Route 160 is a grade separation structure in Springfield, Missouri. This 158 ft long, triple track, three span structure (Figure A.4.1) replaces two existing structures that did not provide sufficient horizontal clearance to widen Route 160  beneath. An intricate staging sequence and a temporary shoofly structure was constructed in conjunction with the replacement bridges to maintain a minimum of two sets of tracks in service at all times during construction. The railroad crosses Route 160 at a skew of 14° 50’ and is supported by three independent superstructures on individual intermediate piers, but all three share a common abutment at each end. The boxes were cast with skewed ends to match the skew angle of the structure, except abutment ends, which are cast square. Each set of tracks is supported by adjacent box beams; the 38 ft end spans are carried by two adjacent, 42 in. prestressed concrete double-cell box beams

Figure A.4.2: Section Through End Span

Figure A.4.3: Section Through Center Span

(Figure A.4.2), while the 82 ft center span is supported on four 72 in. prestressed concrete single cell box beams (Figure A.4.3). The structure was designed in accordance with the 1999 edition of the AREMA Manual for Railway Engineering and was designed for Cooper E-80 loading. All girders are designed as simple span, non-composite beams. The prestressing strands in all girders are ½ in. diameter, 7 wire uncoated, low-relaxation strands. After detensioning, the strands are cut flush with the end of the beam and painted with a waterproofing substance. All strands are straight, no draped strands are used. The double cell box girders in the end spans are placed adjacent to each other, but are not connected. The girders are completely independent and each was assumed to support one half of  the total dead and live load. Each girder contains 48 prestressing strands stressed to 31 kips per  strand for a total prestressing force of 1488 kips. The strands are placed in the bottom flange and up into the webs, with the topmost strand located 18 in. from the bottom. The single cell boxes in the center span are post-tensioned together with two 1 in. diameter tie rods at five locations, equally spaced along the girder (Figure A.4.4). The tie rods are placed in

Figure A.4.4: Plan view of Box Beam

2 in. diameter holes that are cast in internal diaphragms. The BNSF Railway had previously experienced problems with skewed  post-tensioning rods causing racking of single cell box girders in adjacent member structures. To  prevent this from occurring, only the rods at the girder ends are skewed to match the structure skew, with rods at the intermediate locations aligned in a row  perpendicular to the centerline of  the beams. The specified tension for the tie rods was 50 kips each, Figure A.4.5: Detail of Shear Key however only the rods in the intermediate diaphragms were required to attain this full tension. After these rods were tensioned, the skewed rods at the girder ends were tensioned only enough to pull the boxes together without causing racking of the girders. The single cell boxes also employ a 6 in. by 1½ in. longitudinal keyway (Figure A.4.5) to help control differential deflections between girders. Foam backing material is installed to contain the liquid epoxy after the keyway is filled with peagravel. The live load was assumed to be equally distributed to the 4 single cell box girders. The torsional effects on the girders that would result from the uneven loading on the skewed girder  ends were also accounted for in the design. The single cell girders each contain 56 prestressing strands that are stressed to 31 kips per strand for a total prestressing force of 1736 kips. The strands are located in the bottom flange and webs of the girders, with the topmost strand located 20 in. from the top of the girder. Full width bearing pads are provided at each end of the girders. The double cell box girders for the end spans use separate ¾ in. thick by 10 in. wide urethane pads full width under each girder. The four single cell box girders in the center span use two 1¼ in. thick by 10 in. wide laminated, reinforced neoprene pads that extend across the pier cap under  all four girders. Brackets, cut from

Figure A.4.6: Bracket Attachment Details

HP shapes are installed on both sides of the exterior girders at each bearing (Figure A.4.6). The  brackets are field welded to steel  plates that are embedded in the  pier cap and the side of the exterior beams to provide lateral restraint to the girders. Reinforced concrete curbs, 17 in. high, 6 inches wide (Figure A.4.7), used to retain the 16 in. of ballast, are cast on the exterior  edges of the exterior girders at the plant after the prestressing strands are detensioned. A  bonding agent is applied to the top of the girder to improve the  bond of the concrete across the cold joint. Reinforcing bars extend from the top flange into the curbs and inserts are also cast into the outside face of the exterior girders and curbs to attach brackets supporting walkways on each side of each set of tracks. These details reduced the number of steps required for the erection of the superstructure. After setting the girders, only the transverse tensioning rods need to be installed, the walkways bolted on and the ballast and track placed.

Figure A.4.7: Typical Section of Box Beam

In order to maintain a minimum of two sets of tracks in service at all stages of construction, it was necessary to construct a temporary structure on an adjacent alignment. This structure was also constructed using double cell box girders for the superstructure and upon completion of the  permanent bridges, this structure was removed and the box girders were shipped elsewhere to be used on the BNSF system. Double-cell box girders can readily be shipped by truck. Summary Discussion The use of adjacent box girders was central to the economical replacement of a functionally deficient structure carrying an active railroad line over highway traffic. Shipping heavy box girders can be an issue in some instances. The largest girders for this project weighed 62.5 tons, including the curb for the exterior girder. However, since this project was for a railroad bridge, it

was convenient to ship the girders to the site via rail. The high load carrying capacity and simplicity of construction for this system were instrumental in meeting the goal of minimum disruptions to railway traffic.

A.5 - Route 100 over I-44, Missouri

Figure A.5.1: Elevation of Bridge Background The Missouri Route 100 Bridge over I-44 is a two span overpass near Gray Summit, Missouri,  just west of Saint Louis (Figure A.5.1). The structure replaces a 2 lane, 4 span rolled beam  bridge constructed in 1958 that was near the end of its service life. The existing 2 lane overpass had a 28 ft wide roadway while the new roadway is 61 ft-4 in. wide with 4 lanes. The alignment of the new bridge was shifted to the west and staged construction was employed to allow the existing bridge to remain in service while the west half of the new structure was built (phase 1). Traffic was then shifted to the new bridge, the existing bridge was removed and the second stage was constructed (phase 2). The existing structure was on a 9° 15’ 40” skew and the replacement structure is on a 9° skew.

In 2004, a replacement structure was originally designed as a 179 ft-3 in., 4 span, 9 girder line, rolled beam bridge (Figure A.5.2) that matched the existing span layout of the narrow, two lane structure. The overall structure width was 62 ft-8 in. with the bridge centered on a slight, crest vertical curve. After the contract was awarded, the contractor submitted a value engineering

Figure A.5.2: Elevation of Replacement Bridge as Originally Designed

Figure A.5.3: Elevation of Value Engineered Bridge Design

(VE) proposal to switch to a 121 ft, two span, adjacent box girder superstructure with MSE Walls around both abutments to eliminate the short end spans (Figure A.5.3). The VE proposal was prompted by cost penalties applied by the steel industry to the rapid fabrication and delivery schedule for the steel rolled beams. The box beam design provided a slightly wider overall width (64 ft) than required by the original design due to the need to specify a structure width that is a multiple of the box beam width (Figure A.5.4). The value engineered design provided the same horizontal and vertical geometry with the exception that slightly wider shoulders were used on the wider structure.

Figure A.5.4: Cross Section of Adjacent Box Girder Bridge

The structure was designed in accordance with the AASHTO 2002, 17th Edition Load Factor Design Manual. Illinois standard precast, prestressed box girder shapes were used, with “Type B”, 27 in. deep by 48 in. wide boxes (Figure A.5.5) selected for the 60 ft-6 in. spans. The bottom flange contains 23 straight, low-relaxation strands stressed to 31 kips each, for a total prestressing force of 713 kips per girder. The girders were cast with skewed ends to match the 9° skew of the bridge. The box girders were topped with a 5½ in. thick composite, reinforced concrete topping. No special treatments were applied to improve Figure A.5.5: Typical Section of Box Beam  bonding between the top flange and the slab and no additional waterproofing membrane is provided between the slab and girders. The  beams were slightly deeper than the 24 in. deep rolled beams from the original redesign; however the thinner slab allowed the overall structure depth to remain unchanged. The bridge featured Safety Barrier Curbs that were cast-in-place after the slab was poured on top of the girders. Typically, reinforcing bars tie the barrier curb to the slab on Missouri bridges with an 8½ in. thick slab; however on this bridge, with a thinner cast in place slab, the bars were embedded in the exterior girders of the bridge. These vertical bars projected through the slab to tie to the remaining, standard horizontal and vertical safety barrier curb reinforcing bars. These bars, and the lack of a longitudinal keyway on the exterior beam face, were the only differences between the interior and exterior box girders. The adjacent box structure was originally submitted as two simple spans with a non-composite slab. However after MoDOT reviewed the plans, they requested that the spans be made continuous for live loads, similar to their typical detail for I-beam bridges. This is accomplished  by making the slab composite with the girders and placing additional negative moment reinforcing located in the slab over the piers to provide the negative moment capacity. To  provide a positive moment connection at the piers, the prestressing strands were cut with a 2 ft 3 in.  projection at each end of  the box girders and these strands were bent up at the intermediate diaphragm (Figure A.5.6) and the abutment backwalls. A tie  bar was placed across each row of bent strands and the concrete from the Figure A.5.6: Section at Intermediate Bent

Figure A.5.7: Plan of Box Girders Showing Diaphragms

slab pour was allowed to flow into the gap between the girder ends at the pier encasing the strands. At the abutments, an 8 in. thick backwall was cast against the skewed ends of the girders at the same time as the slab pour to encase the strands and tie bars. Although these modifications and additional details were requested by the bridge owner, the bridge designer reported that the changes did not result in any significant structural advantage. The girder section was not reduced and 2 strand reduction in the prestressing strands per girder was not an economical trade off for  the additional mild reinforcing steel required in the slab. The mild reinforcement was desired by the owner to minimize cracking in the deck slab in the negative moment region. The bridge is an integral structure, with no expansion joints in the bridge. Transverse connections between the girders are provided by lateral post tensioning, shear keys and the composite slab. The girders are laterally post-tensioned with 1 in. diameter rods placed in 3 in. diameter  sleeves that are cast in internal diaphragms located at mid-span (Figure A.5.7). The sleeves are aligned on a single line matching the 9° skew of the structure. The girders from the first  phase were connected sequentially with 3 ft-11in. long rods and 3 in. thread sleeves as each girder is placed next to the previously set girder. After all the girders from phase one were set and the rods installed, they were post-tensioned Figure A.5.8: Typical Section of Box Beam

together to a total force of 25.5 kips. Once all the girders for the second phase were placed adjacent to the first phase, a single rod was threaded through all the phase 2 boxes and connected to the last 3 in. thread sleeve on the exterior of the final box from phase one. A tension of 25.5 kips was applied. The 4 in. tall by ¾ in. wide longitudinal keyways are located between girders (Figure A.5.8) and are grouted with non-shrink grout after the tensioning of the transverse posttensioning rods. The keyway surfaces were cleaned by sandblasting prior to erection of the girders. The joint between the first and second phases was grouted in an overnight operation when the traffic on the bridge was at a minimum. Each corner of the box girders are supported by a plain neoprene bearing pad. Adjacent  box girders actually share a single 2 ft-5 in. wide pad (Figure A.5.9). Vertical holes, 2 in. in diameter, are cast 7 in. from each end of the girders which align with 3 in. diameter  holes in the bearing pads. After   placing the girders, 1¼ in. diameter holes are drilled though these openings 9 in. into the beam cap. Dowel bars ¾ in. diameter by 18 in. long are placed into the holes and grouted in place with nonshrink grout (Figure A.5.10) after the transverse posttensioning and prior to grouting the longitudinal girder keys. Vent holes (¼ in. diameter) are cast into the top flange of the  box girder and ¾ in. diameter  drain holes are cast in the  bottom. Three holes are located at top and bottom of each end of the girder and at each side of  the internal diaphragm. The vent holes are plugged when the slab is poured on top of the girders; however the drain holes are intended to remain open to provide drainage for  any water intrusion that may occur.

Figure A.5.9: Plan View of Bearing Pads

Figure A.5.10: Dowel Bars at Abutments

Figure A.5.11: Route 100 over I-44 Summary Discussion Missouri Route 100 over I-44 was the second Missouri Department of Transportation project to utilize adjacent box girders for a highway bridge. Although the value engineering submitted was for two simple spans, MoDOT requested some changes to improve serviceability. The design was revised to include additional mild reinforcing over the piers to account for continuity and control cracking in the deck. The longitudinal joint in the deck slab was also offset 1 ft. from the edge of the phase 1 exterior box. Addition of the mild steel did not significantly improve the structural capacity and had a negligible effect on the load rating of the structure.

With the exterior face of the barrier curb aligned with the exterior face of the outside beam, any noticeable sweep in the box beams will show up as a sweep in the barrier curb. To ensure a straight barrier curb, the contractor set a straight line on the slab for the inside face of the curb and formed the outside face of the curb extra wide, so that any sweep in the beam would be covered by the extra width in the barrier curb. This maintained the full roadway width, and made any construction tolerances less noticeable by creating a slight overhang from the curb to the slab, where chamfered corners provide a line break on the bridge fascia. This project demonstrates the effectiveness of shallow box girders for a highway overpass. The 22:1 span to depth ratio provided an economical solution in competition with a rolled beam structure. Careful construction by the contractor and the clean lines of the adjacent box beam system combined to create an efficient as well as aesthetically pleasing structure (Figure A.5.11).

Appendix B: PCI New England Recommendations This section contains the construction practice recommendations from PCI Northeast Region Technical Committee for adjacent member bridges skewed less than 30 degrees and for bridges skewed more than 30 degrees.

B.1 Sequence of Construction for Butted Box and Butted Deck  Beam Superstructures (Skews < 30°) A)

Layout Working Lines Working lines shall be laid out on the beam seat for the entire width of the bridge. All working lines are to be measured from a common working point. The working lines are to be based on the nominal beam widths, plus a joint.

•

•

B)

Verify Beam Seat Elevations Take elevations at beam seats. If seats are high, grind to correct elevations. If seats are low, shim as required. Shims to be high durometer neoprene or high density plastic. Install bearing pads.

•

•

•

•

C)

Erect Beams Pressure wash sides of beams. Beams shall be placed to fit within the working lines. As work progresses, install hardwood wedges between adjacent beams to maintain  proper shear key joint opening. Install a minimum of one wedge at each transverse tie location.

•

•

•

D)

Install Polyethylene Closed Cell Backer Rod as Joint Filler at Shear Key Locations. Filler shall be placed below the bottom of the shear key joints as shown on the Plans and shall conform to key depth change in configuration at the transverse tie locations. Filler shall be installed sufficiently tight to prevent loss of the shear key grout.

•

E)

Install Transverse Ties Feed transverse ties through ducts. Verify that hardwood wedges are in place as required to prevent slippage of beams. Using a calibrated jack, post-tension transverse ties to approximately 5,000 lbs. to remove sag in the-tie and to seat the chuck. For stage construction, the second stage transverse tie ducts shall be protected at the shear key joints by installing second stage transverse ties or placing Styrofoam over  the duct opening.

•

•

•

•

F)

Grout Shear Key A correctly grouted shear key joint is necessary to ensure the structural integrity of  the superstructure. Clean the shear key joint with an oil free air-blast immediately prior to grout  placement. Verify that the backer rod is still in place. Additional shear key joint preparation and grout placement shall be per the Manufacturer's recommendations. Shear key joints shall be carefully rodded to eliminate voids. •

•

•

•

G)

Post-Tension Transverse Ties Shear key grout shall attain a minimum compressive strength of 1500 psi, based on the Manufacturer's recommendations, prior to stressing. Using a calibrated jack operated by qualified personnel, post-tension transverse ties to 30,000 lbs. beginning with inner most ties and proceeding symmetrically about midspan towards the member ends. Inner ties shall be re-checked to ensure that the ties have 30,000 lbs. of tension. (For box beams with top and bottom transverse ties: tension the bottom tie to 15,000 lbs. then tension the top tie to 15,000 lbs. Repeat the sequence once more so that each transverse tie has 30,000 lbs. of tension.) •

•

H)

Finish Work  Remove wedges and patch the deck and fascia beams at transverse tie locations. Place abutment concrete above the beam seat construction joint. Place brush curb and overlay concrete.

•

•

•

B.2 Sequence of Construction for Butted Box and Butted Deck  Beam Superstructures (Skews > 30°) A)

Layout Working Lines Working lines shall be laid out on the beam seat for the entire width of the bridge. All working lines are to be measured from a common working point. The working lines are to be based on the nominal beam widths. •

•

B)

Verify Beam Seat Elevations Take elevations at beam seats. If seats are high, grind to correct elevations. If seats are low, shim as required. Shims to be high durometer neoprene or high density plastic. Install bearing pads. •

•

•

•

C)

Erect Beams Pressure wash sides of beams. Beams shall be placed to fit within the working lines. Each beam is erected with a reset dead-end chuck and transverse tie in place. As each  beam is erected, the live end of the transverse tie from the preceding beam is worked through the duct. Install hardwood wedges between adjacent beams to maintain proper shear key joint opening. Install a minimum of two wedges at each transverse tie location, one on top and the other under the beam. Using a calibrated jack operated by qualified personnel, post-tension transverse ties to 30,000 lbs. (For box beams with top and bottom transverse ties: tension the bottom tie to 15,000 lbs. then tension the top tie to 15,000 lbs. Repeat the sequence once more so that each transverse tie has 30,000 lbs. of tension) Repeat above steps until all beams are erected.

•

•

•

•

•

•

D)

Install Polyethylene Closed Cell Backer Rod as Joint Filler at Shear Key Locations. Filler shall be placed below the bottom of the shear key joints as shown on the Plans. Care shall be used to seal the joint under the transverse tie and maintain the proper  shape of the key at all transverse tie locations. Filler shall be installed sufficiently tight to prevent the loss of the shear key grout.

•

E)

Grout Shear Key A correctly grouted shear key joint is necessary to ensure the structural integrity of  the superstructure. Clean the shear key joint with an oil free air-blast immediately prior to grout  placement. Verify that the backer rod is still in place. Additional shear key joint preparation and grout placement shall be per the Manufacturer's recommendations. Shear key joints shall be carefully rodded to eliminate voids.

•

•

•

•

F)

Finish Work  Remove wedges, and patch the deck and fascia beams at transverse tie locations. Place abutment concrete above the beam seat construction joint. Place brush curb and overlay concrete.

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•

•

Appendix C: Survey Questionnaire Responses

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Box Beam Construction

Keyways

Prestressing

Arizona

California

A.1

Use Box Beam Bridges?

yes

yes

yes

A.2.

Location

Highway Bridges

Highway & Pedestrian Bridges

Highway, RR & Pedestrian Bridges

A.3.

Shape of Box?

 AASHTO/PCI & Other - Oregon DOT stnd

AASHTO/PCI

AASHTO/PCI, State standard & other 

A.4.

Any Skew Angle Limitation?

yes

yes

No

A.4.1.

Max. Skew Angle Permitted?

30 degreees

30 degrees

-

A.5.

Waterproof or Coat the Sides?

no

no

no

A.6.

Any Differential Camber Restr ictions?

yes

no

no

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

temporary vertical jacking

overlay

-

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

cut flush

cut flush

-

-

no

-

A.8.2

If yes, with what material?

-

-

-

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

A.9.1

Deck Slab & Overlay

Alaska

yes

no

no

around strand ends

-

-

A.9.2

With what material? Unspecified waterproofing material?

zinc-rich paint

-

-

B.1.

Use with CIP Composite Deck Slab?

yes - sometimes

yes

yes

B.1.1

Thickness of Slab?

4"

5"

7" to 8"

B.2.

Use Overlay?

on top of CIP slab & in lieu of CIP slab

on top of CIP slab

on top of CIP slab

B.3.

What Type of Overlay?

a sp ha lt w /w at er pr oo fi ng m em br an e

a sp ha lt : w/ o wa te rp ro of in g me mb ra ne

A sp ha lt w /w at er pr oo fi ng m em br an e

B.4.

Thickness of Overlay?

3" & 4"

2"

3"

C.1.

Type of Void?

-

polystyrene, wood

Cardboard one

C.2

Cast in One-or two Part Placement?

one

one

C.2.1.

Monolithic or Cold Joint?

-

-

-

C.3.

Do you use Hold Downs for Voids?

no

no

yes

C.4.

Is Hold down sacrificial?

-

no

yes

C.5.

Use HPC?

-

no

no

C.5.1

Type of HPC? (Box)

if f'c > 7.5 ksi is HPC then yes all P/S

-

-

C.5.2.

Type of HPC? (Slab)

No, typically f'c = 4ksi for slabs

-

-

D.1.

Use Keyways Between Boxes?

yes

yes

yes

D.2.

Are they Different from AASHTO?

-

no

no

D.2.1.

Any Sketch Attached?

-

-

-

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

yes

no

yes

before grout placement per manufacturer's

-

precast plant

D.4.

What Filler Material used?

non-shrink, non-metallic, cement based grout (ASTM C-1107 Type C) 28 day f'c=62 Mpa

non-shrink grout

grout

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

no

no

no

-

-

-

D.6.

Any Experience of Water Leakage?

no

no

no

D.7.

When do you Grout Keyways?

after - P/T not always used but always use a tie of some type

after

before

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning

pretensioning

both

low-relaxation - 1/2" dia

1/2" dia

low-relaxation - 1/2" dia

E.3.

Type of Strand Layout?

straight

straight

harped, draped, combination - combine harped and straight

E.4.

Any Unbonded Strands?

yes

no

yes

E.5.

Any Transverse Prestress?

both - see above

yes

yes

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

-

bars

strands & bars

1/2" dia

-

1/2"

E.6.2.

No. of Strands/Tendon?

-

-

-

E.6.3.

Low -relaxation or Stress Relieved?

low-relaxation

-

low-relaxation

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

Alaska

Arizona

California

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

1" dia

1.5"

#7, #8

150ksi

36ksi

(HS) 150 ksi

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

1.75" CL strand-bottom dist. Minimum

mid-depth

middle of the beam

E.8.

Magnitude of Transverse PT?

no - standard practice to pro vide 1" dia (min) rod at mid-span diaphragm location

no (just have sufficient to keep the units together)

yes - PCI manual

E.9. E.9.1.

Spacing of PT Longitudinal

-

-

-

2"

2"

20'+-

E.9.2.

Transverse

-

-

-

F.1.

Type of Bearings?

Plain & Laminated Elastomeric - depends upon span length and need

Laminated elastomeric

laminated elastomeric

F.1.1.

Type of Laminate?

steel

steel

-

F.2.

T ype of Lateral Movement Restraint?

dowel pins & shear keys or blocks

dowel pins

dowel pins

F.3.

An y Experience with uneven seating?

no

no

no

F.3.1.

Type of Support?

-

-

-

G.1.

Any Lessons, Experiences or Ideas?

yes - there has been concern that the concrete cover within the box may not be provided but there is no inspection process for checking see Idaho DOT for info.

no

 Attached please find three types of precast prestressed box beam Caltrans have used for  bridge design

Yes

G.2.

Any State Standard Drawings?

-

no

G.2.1. G.2.2. G.3.a

Any Connection Weldment Drawing? Any Key Sketch Attached? Name of Contact Person

no

no

no

no

no

yes

Elmer E. Marx PE

Pe-Shen Yang

G.3.b

Title:

Technical Engineer II

Assistant State Bridge Engineer  

G.3.c

Phone No.

907-465-6941

602-712-8606

Richard Land / Jim Ma State Bridge Engineer / Prestressed Concrete Technical Specialist 916-227-8807 / 916-227-8175

G.3.d

e-mail:

[email protected]

[email protected]

[email protected] / [email protected]

G.3.e

Agency

S ta te o f A la sk a D OT & P F

A ri zo na D ep ar tm en t o f T ra ns po rt at io n

C al if or ni a D ep ar tm en t o f T ra ns po rt at io n

Additional Comments

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Box Beam Construction

Prestressing

Delaware

A.1

Use Box Beam Bridges?

yes

yes

yes

Location

Highway, RR & Pedestrian Bridges

highway bridges

Highway Bridge

A.3.

Shape of Box?

State standard

AASHTO/PCI

AASHTO/PCI

no Though not limited, a significant consideration for  shear and uniform seating of the boxes

no

no

-

-

A.4.

Any Skew Angle Limitation?

A.4.1.

Max. Skew Angle Permitted?

A.5.

Waterproof or Coat the Sides?

no

no

yes

A.6.

Any Differential Camber Restr ictions?

yes - 1" max differential over pedestrian use. W e limit actual cambers to 1" over design cambers

no

no

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

overlay - normal differentials are dealt w/by variation in the composite deck thickness, excess differentials dealt w/on a case by case basis that may include sorting the girders or jacking.

Overlay

Overlay

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

A.8.2

If yes, with what material?

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

-

Recess by melting with torch

cut flush

yes

yes

-

Normally cut to project 3" when they will be embedded in CIP concrete, recessed & patched w/an epoxy grout when not to be embedded

not specified

-

no

yes

yes

-

-

entire end

A.9.2

With what material? Unspecified waterproofing material?

-

-

bitumastic compound or waterproofing compound

B.1.

Use with CIP Composite Deck Slab?

yes

no

yes

B.1.1

Thickness of Slab?

-

5"

B.2.

Use Overlay?

In lieu of CIP slab

no

B.3.

What Type of Overlay?

W ith waterproofing membrane

-

B.4.

Thickness of Overlay?

3"

2.5"

-

C.1.

Type of Void?

other - not specified, but current suppliers use Styrofoam

-

polystyrene

One

one

4.5" minimum on side-by-side boxes. Actual thickness in practice tends to vary between 5.5" and 9", 8" min. on spread boxes on top of CIP slab asphalt: w/ waterproofing membrane (typically 3" HBP over waterproofing membrane. This overlay is omitted where a bare concrete riding surface is desired.)

C.2

Cast in One-or two Part Placement?

C.2.1.

Monolithic or Cold Joint?

one - (one supplier is experimenting, so far  successfully with a two part placement) -

C.3.

Do you use Hold Downs for Voids?

C.4.

Is Hold down sacrificial?

-

-

no

no

no

-

-

-

C.5.

Use HPC?

-

no

yes

C.5.1

Type of HPC? (Box)

f'c ,+ 8500 psi, f'ci <-6500psilimit on usual designs

-

6,000psi low permeability to 8,000psi

Type of HPC? (Slab)

 A mix has recently become available in the specs., appropriate for slabs that are not replacable and which have neither a protective membrane or  sacrifical concrete overlay. It has not yet been used on pretensioned precast box girder structures at this time.

-

6,000psi

D.1.

Use Keyways Between Boxes?

no

yes

yes

D.2.

Are they Different from AASHTO?

-

yes

no

D.2.1.

Any Sketch Attached?

-

yes

-

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

-

no

yes

-

after erection

D.4.

What Filler Material used?

non-shrink grout

nonshrink grout

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

keyways and transverse PT are often used side-byside box girder bridges carrying railroads. CDOT does not have standard details or guidelines for this application. no

no

yes

-

no

-

D.6.

Any Experience of Water Leakage?

no - not when a CIP deck has been used

no

no

D.7.

When do you Grout Keyways?

-

before

after

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning - typically pretensioning

pretensioning

pretensioning

low-relaxation

low-relatation - 1/2" dia

E.3.

Type of Strand Layout?

straight

straight

no

yes

C.5.2.

Keyways

Connecticut

A.2.

A.9.1

Deck Slab & Overlay

Colorado

E.4.

Any Unbonded Strands?

low-relaxation - 1/2" dia straight - Highway structures have used straight & RR structures straight and harped. The standard detail provides for both but supppliers have elected to use straight. yes

E.5.

Any Transverse Prestress?

no

yes

yes

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

-

strands

strands & bars

-

1/2"

-

E.6.2.

No. of Strands/Tendon?

-

-

-

E.6.3.

Lo w-relaxation or Stress Relieved?

-

low-relaxation

-

 

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

Colorado

Connecticut

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

-

-

1.5"

-

-

50ksi

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

-

D/2

1/2 depth

E.8.

Magnitude of Transverse PT?

-

No

no

E.9. E.9.1.

Spacing of PT Longitudinal

-

-

-

-

2"

1.5"

E.9.2.

Transverse

-

n/a

varies - based on span length

F.1.

Type of Bearings?

Plain elastomeric & Laminated elastomeric - plain elastomeric is sufficient for the majority of integral designs

either plain or laminated allowed

plain elastomeric

F.1.1.

Type of Laminate?

steel, shen used

steel

-

F.2.

T ype of Lateral Movem ent Restraint?

other - Usually embedded in CIP concrete diaphragms, otherwise bearing devices specifically designed for this.

shear keys or blocks

dowel pins

F.3.

Any Experience with uneven seating?

yes

yes

yes

F.3.1.

Type of Support?

full support & 3-point support - W e recently started using 3-point support for skewed bridges

4-point support

full support each end

G.1.

Any Lessons, Experiences or Ideas?

yes - For box girders embedded in CIP concrete diaphragms, instances of poor seating have not as yet resulted in any actual in-service distress

G.2.

Any State Standard Drawings?

yes

Yes

no

G.2.1. G.2.2. G.3.a

Any Connection Weldment Dr awing? Any Key Sketch Attached? Name of Contact Person

no

-

yes

no

-

no

Mark Leonard

Gordon Barton

Dennis O'Shea

G.3.b

Title:

Colorado Bridge Engineer

Trans. Principal Engineer

Asst. Director - Design

G.3.c

Phone No.

303-757-9309

860-594-3308

302-760-2288

G.3.d

e-mail:

[email protected]

[email protected]

[email protected]

G.3.e

Agency

Colorado DOT Bridge Design

Connecticut DOT

Delaware Dept of Transportation

Additional Comments

Delaware

We have had failures of standard shear keys. yes - we are getting cracking longitudinally Since we instituted full depth shear keys as with the welded connections and are developed by PCI New England technical considering elminating. Committee, we have had no failures

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Box Beam Construction

Keyways

Prestressing

Idaho

Illinois

A.1

Use Box Beam Bridges?

yes

yes

yes

A.2.

Location

Highway bridges

Highway Bridges

Highway bridges

A.3.

Shape of Box?

 AASHTO/PCI

State Standard

AASHTO/PCI

A.4.

Any Skew Angle Limitation?

no

no

no

A.4.1.

Max. Skew Angle Permitted?

-

-

-

A.5.

Waterproof or Coat the Sides?

no

no

no

A.6.

Any Differential Camber Restr ictions?

no

no

no

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

-

Overlay

other (shimming)

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

cut flush

Cut Flush

Burn flush

-

-

no

A.8.2

If yes, with what material?

-

The strand ends are painted w/zinc-rich paint

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

A.9.1

Deck Slab & Overlay

Georgia

yes

no

yes

1/8"

-

strands

A.9.2

With what material? Unspecified waterproofing material?

epoxy mortar

-

tar

B.1.

Use with CIP Composite Deck Slab?

no

Yes

no

B.1.1

Thickness of Slab?

-

5"

-

B.2.

Use Overlay?

in lieu of CIP slab

In lieu of CIP slab

no

B.3.

What Type of Overlay?

asp halt w/ ou t w at er pr oo fin g m em br an e

A sp halt w /w at er pr oo fin g m em br an e

asp halt w/ wat er pr of fin g m em br an e

B.4.

Thickness of Overlay?

1.5" - 8"

2"

3"

C.1.

Type of Void?

not specified

not specified

cardboard

 

C.2

Cast in One-or two Part Placement?

one

one

one & two

C.2.1.

Monolithic or Cold Joint?

mololithic required

-

monolithic required

C.3.

Do you use Hold Downs for Voids?

yes

no

yes

C.4.

Is Hold down sacrificial?

yes - low friction roller

-

no-we use metal hold down devises and remove them after pour 

C.5.

Use HPC?

no

no

no

C.5.1

Type of HPC? (Box)

-

-

-

C.5.2.

Type of HPC? (Slab)

-

-

-

D.1.

Use Keyways Between Boxes?

yes

yes

yes

D.2.

Are they Different from AASHTO?

no

yes

no

D.2.1.

Any Sketch Attached?

-

yes

-

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

no

yes

yes

-

precast plant

precast plant

D.4.

What Filler Material used?

expanded mortar grout

a non-metallic non-shrink portland cement grout with a 28 day strength of 5800psi

non-shrink grout

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

no

yes

no

-

yes

-

D.6.

Any Experience of Water Leakage?

no

yes

yes

D.7.

When do you Grout Keyways?

after

after

after

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning

pretensioning

pretensioning

low-relaxation, stress relieved, 1/2" dia

low-relaxation

low-relaxation - 1/2" dia

E.3.

Type of Strand Layout?

harped & straight

harped, straight

straight

E.4.

Any Unbonded Strands?

no

no

no

E.5.

Any Transverse Prestress?

no

yes

no

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

-

bars

-

-

-

-

E.6.2.

No. of Strands/Tendon?

-

-

-

E.6.3.

Lo w-relaxation or Stress Relieved?

-

-

-

 

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

Georgia

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

-

7/8"

-

-

92ksi

-

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

-

mid-depth

-

E.8.

Magnitude of Transverse PT?

-

no

-

E.9. E.9.1.

Spacing of PT Longitudinal

-

-

-

2"

none

-

E.9.2.

Transverse

-

30'

-

F.1.

Type of Bearings?

Plain Elastomeric

laminated elastomeric

plain elastomeric

F.1.1.

Type of Laminate?

-

steel

-

F.2.

T ype of Lateral Movem ent Restraint?

Dowel Pins

dowel pins

dowel pins

F.3.

Any Experience with uneven seating?

no

no

yes

F.3.1.

Type of Support?

-

-

4 point support

G.1.

Any Lessons, Experiences or Ideas?

Idaho

yes - We use a few of these types bridges each yes, The only way we have found to prevent year. It is usually for small bridges that have a maximum span length of 40ft or less and we leakage between box beams is to construct a CIP need a very shallow superstructure for vertical slab on top clearance reasons.

Illinois

-

G.2.

Any State Standard Drawings?

no

yes

no

G.2.1. G.2.2. G.3.a

Any Connection Weldment Dr awing? Any Key Sketch Attached? Name of Contact Person

no

yes

no

no

yes

no

Paul V. Liles Jr.

Ken Clausen

Andrew J. Keenan

G.3.b

Title:

State Bridge Engineer

Engineer Manager I

VP

G.3.c

Phone No.

404-656-5280

208-334-8554

815-459-4545

G.3.d

e-mail:

[email protected]

[email protected]

[email protected]

G.3.e

Agency

Georgia DOT

Idaho Transportation Dept.

Prestress Eng. Corp.

Additional Comments

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Box Beam Construction

Keyways

Prestressing

Indiana

Kentucky

A.1

Use Box Beam Bridges?

yes

yes

yes

A.2.

Location

Highway bridges

Highway bridges

Highway, RR & Pedestrian Bridges

A.3.

Shape of Box?

State Standards

State Standard

State Standard

A.4.

Any Skew Angle Limitation?

yes

yes

yes

A.4.1.

Max. Skew Angle Permitted?

35 degrees

30 degrees

45 degrees

A.5.

Waterproof or Coat the Sides?

no

yes - Clear non-epoxy Portland Cement Concrete Sealer 

yes - calcium nitrate & mason coating

A.6.

Any Differential Camber Restr ictions?

no

no

no

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

Overlay, other (PC mortar fairing course)

other - the difference is made up by increasing the deck thickness (fillet)

-

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

Burn flush

Cut flush

cut flush

-

-

yes

A.8.2

If yes, with what material?

-

grout

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

yes

no

no

all

-

-

A.9.1

Deck Slab & Overlay

Illinois

A.9.2

With what material? Unspecified waterproofing material?

two coats of asphalt paint

-

-

B.1.

Use with CIP Composite Deck Slab?

no

yes

yes

B.1.1

Thickness of Slab?

-

8" for spread beams & 5" for adjacent beams

5" on side by side & 8" on spread boxes

B.2.

Use Overlay?

in lieu of CIP slab

no

no

B.3.

What Type of Overlay?

asphalt w/waterproofing membrane & w/out waterproofing membrane; other (concrete)

-

-

B.4.

Thickness of Overlay?

5" min.

-

-

C.1.

Type of Void?

cardboard

polystyrene

polystyrene one

C.2

Cast in One-or two Part Placement?

-

two

C.2.1.

Monolithic or Cold Joint?

monolithic required

monolithic required

-

C.3.

Do you use Hold Downs for Voids?

yes

yes

no

C.4.

Is Hold down sacrificial?

yes-saddles or chairs placed on top of void with tie wires yes - bands are placed around the polystyrene and spacer templates and tie-downs are used

-

C.5.

Use HPC?

no

no

no

C.5.1

Type of HPC? (Box)

-

-

-

C.5.2.

Type of HPC? (Slab)

-

-

-

D.1.

Use Keyways Between Boxes?

yes

yes

yes

D.2.

Are they Different from AASHTO?

yes

yes

yes

D.2.1.

Any Sketch Attached?

-

-

-

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

yes

no

no

-

-

grout no

D.4.

What Filler Material used?

non-shrink grout

currently we use a non-shrink grout but we are in the process of switching to an epoxy grout

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

no

no

-

-

-

D.6.

Any Experience of Water Leakage?

yes

yes

no

D.7.

When do you Grout Keyways?

n/a

currently we do not use post-tensioning

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning

pretensioning

pretensioning

1/2" dia

low-relaxation = 1/2" dia

low-relaxation

E.3.

Type of Strand Layout?

straight

straight

draped & straight

E.4.

Any Unbonded Strands?

no

Any Transverse Prestress?

no

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

-

yes no - a threaded rod is used but not posttensioned -

yes

E.5.

bars

-

-

-

E.6.2.

No. of Strands/Tendon?

-

-

-

E.6.3.

Lo w-relaxation or Stress Relieved?

-

-

-

after  

yes

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

Illinois

Indiana

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

-

-

1" dia

-

-

60 ksi

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

-

-

varies 6" to 12"

E.8.

Magnitude of Transverse PT?

-

-

no

E.9. E.9.1.

Spacing of PT Longitudinal

-

-

-

2.75"

none specified

8"

E.9.2.

Transverse

-

-

12"

F.1.

Type of Bearings?

others - (fabric pad)

laminated elastomeric

laminated elastomeric

F.1.1.

Type of Laminate?

-

steel

steel

F.2.

T ype of Lateral Movem ent Restraint?

dowel pins

shear keys or blocks

dowel pins

F.3.

Any Experience with uneven seating?

-

yes

yes

F.3.1.

Type of Support?

4 point support

full support each end

full support each end

G.1.

Any Lessons, Experiences or Ideas?

yes - Many changes were made to our details over the last 20 years that considerably improved the yes - Our bridge rehabilitation squad performance & reduced the water leakage between commented that box beams are hard to rehab adjacent boxes 1.Placing the bearing pads under the especially when composite with the deck. edge of the beam rather than u nder the middle. This They also suggest that we should use an prevented beam rocking during grouting the shear keys. overlay on top of the deck when the structure 2.Blast cleaning of the key surfaces. 3.The use of nonis built shrink grout in lieu of sand and cement mortar. 4.The use of corrosion inhibitor in the concrete mix

Kentucky

-

G.2.

Any State Standard Drawings?

yes

yes

G.2.1. G.2.2. G.3.a

Any Connection Weldment Dr awing? Any Key Sketch Attached? Name of Contact Person

no

no

no

yes

yes

yes

Slah Y. Khayyat

Mary Jo Hamman

G.3.b

Title:

Bridge Standards and Specifications Unit Chief

desig n Develo pment Section manager

yes

Steve Goodpaster   Director Division Bridge Design

G.3.c

Phone No.

217-785-2926

317-232-5159

502-564-4560

G.3.d

e-mail:

[email protected]

[email protected]

[email protected]

G.3.e

Agency

IL.DOT / Bureau of Bridges and Structures

Indiana Department of Transportation

Kentucky

Additional Comments

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Maryland

Massachusetts

yes Highway bridges (for RR bridges, see Central  Artery Project)

A.1

Use Box Beam Bridges?

yes - solid slab boxes

A.2.

Location

Highway bridges

A.3.

Shape of Box?

State Standard

State standard

State standard

Box Beam Construction

Keyways

Prestressing

yes Highway Bridges

A.4.

Any Skew Angle Limitation?

no

no

no

A.4.1.

Max. Skew Angle Permitted?

-

-

-

A.5.

Waterproof or Coat the Sides?

no

no

no

A.6.

Any Differential Camber Restr ictions?

no

yes

yes

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

-

other

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

cut flush & burn flush

-

burn flush

-

yes

yes

A.8.2

If yes, with what material?

-

cut off 15mm into the beam & filled w/cement mortar 

asphalt tar 

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

no

no

no

-

-

-

A.9.1

Deck Slab & Overlay

Michigan

 

other - beams rejected or forced together by transverse post tensioning

A.9.2

With what material? Unspecified waterproofing material?

-

-

-

B.1.

Use with CIP Composite Deck Slab?

no

yes - (for spread beam configuration only)

yes

B.1.1

Thickness of Slab?

-

200mm

6"

B.2.

Use Overlay?

In lieu of CIP slab

on top of CIP slab

no

B.3.

What Type of Overlay?

other high performance concrete

asphalt: w/waterproofing membrane

-

B.4.

Thickness of Overlay?

4" min

80 mm

-

C.1.

Type of Void?

voids are not permitted

polystyrene (however, this is not specified)

polystyrene

C.2

Cast in One-or two Part Placement?

one

two

two

C.2.1.

Monolithic or Cold Joint?

-

monolithic required

cold joint acceptable

C.3.

Do you use Hold Downs for Voids?

-

no

no

C.4.

Is Hold down sacrificial?

-

none specified

no - we do not dictate this fabrication detail

C.5.

Use HPC?

no

yes

no

C.5.1

Type of HPC? (Box)

-

yes

-

C.5.2.

Type of HPC? (Slab)

-

-

-

D.1.

Use Keyways Between Boxes?

yes

yes

yes

D.2.

Are they Different from AASHTO?

no

yes

yes

D.2.1.

Any Sketch Attached?

-

-

-

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

no

yes

no

-

precast plant

-

D.4.

What Filler Material used?

high strength grout

polymer-modified, cementitious, fast-setting, free flowing mortar 

non shrink grout

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

no

no

no

-

-

-

D.6.

Any Experience of Water Leakage?

no

yes

no

D.7.

When do you Grout Keyways?

after

before

before

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning

pretensioning

pretensioning

low-relaxation - 1/2" dia

low-relaxation - 1/2" dia

low-relaxation - 0.6" dia

E.3.

Type of Strand Layout?

straight

harped & straight

combination - we go to great lengths to avoid harped strands but do use them on rare occasions

E.4.

Any Unbonded Strands?

no

yes

yes

E.5.

Any Transverse Prestress?

no

yes

yes

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

-

strands

strands

-

1/2"

-

E.6.2.

No. of Strands/Tendon?

-

-

-

E.6.3.

Lo w-relaxation or Stress Relieved?

-

low-relaxation

low-relaxation

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

Maryland

Massachusetts

Michigan

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

-

-

-

-

-

varies - see attached sheet 6.65.13

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

-

See bridge Manual drawings, the target is the center of the beam

E.8.

Magnitude of Transverse PT?

-

no

yes - see sheet 6.65.13

E.9. E.9.1.

Spacing of PT Longitudinal

-

-

see attached

2"

50.8mm

-

E.9.2.

Transverse

-

see Bridge Manual drawings

-

F.1.

Type of Bearings?

plain & laminated elastomeric

Laminated elastomeric - for spans less than 15m plain strips 25mm by 130mm are used w/o design

plain & laminated elastomeric

F.1.1.

Type of Laminate?

stainless steel

steel

steel

F.2.

T ype of Lateral Movem ent Restraint?

dowel pins

shear key or blocks

dowel pins

F.3.

Any Experience with uneven seating?

no

no

no - only for skewed

F.3.1.

Type of Support?

-

3-point support & 4-point support

full support each end

G.1.

Any Lessons, Experiences or Ideas?

yes - see attached PCI article

Please call 617-973-7570 if you would like to discuss

-

yes

G.2.

Any State Standard Drawings?

yes - see attached PCI article

no

G.2.1. G.2.2. G.3.a

Any Connection Weldment Dr awing? Any Key Sketch Attached? Name of Contact Person

no

no

no

yes - see attached PCI article

no

yes

John Narer, PE

Alexander K. Bardow

G.3.b

Title:

Seniot Project Engineer

Bridge Engineer

Steve Beck Bridge Supervising Engineer  

G.3.c

Phone No.

410-545-8368

617-973-7570

517-373-0097

G.3.d

e-mail:

-

[email protected]

[email protected]

G.3.e

Agency

Maryland State Highway Administration

Massachusetts Highway Department

Michigan DOT

Additional Comments

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Box Beam Construction

Keyways

Prestressing

Nevada

New Hampshire

A.1

Use Box Beam Bridges?

yes

yes

yes

A.2.

Location

Highway Bridges

Highway Bridges

Highway Bridges

A.3.

Shape of Box?

Other

Other

Other

 

A.4.

Any Skew Angle Limitation?

no

no

no

A.4.1.

Max. Skew Angle Permitted?

-

-

-

A.5.

Waterproof or Coat the Sides?

no

no

no

A.6.

Any Differential Camber Restr ictions?

no

yes

yes

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

Other - hasn't been a problem

overlay

overlay

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

-

cut flush

recess by melting torch

ours actually extend at least 1"

-

yes

A.8.2

If yes, with what material?

-

-

cementitous grout

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

no

no

yes

-

-

entire end cross-section

A.9.1

Deck Slab & Overlay

Missouri

A.9.2

With what material? Unspecified waterproofing material?

-

-

bitumastic material

B.1.

Use with CIP Composite Deck Slab?

yes

yes

yes

B.1.1

Thickness of Slab?

6"

4 to 6"

3" min thickness at curb and additional

B.2.

Use Overlay?

-

typically not

on top of CIP slab

B.3.

What Type of Overlay?

-

-

asphalt w/waterproofing membrane

B.4.

Thickness of Overlay?

-

-

2.5 "

C.1.

Type of Void?

polystyrene & cardboard

Other - not specified

polystyrene

C.2

Cast in One-or two Part Placement?

two

one

one

C.2.1.

Monolithic or Cold Joint?

cold join acceptable

-

monolithic required

C.3.

Do you use Hold Downs for Voids?

-

no

no

C.4.

Is Hold down sacrificial?

yes - up to fabricator

-

-

C.5.

Use HPC?

no

yes

-

C.5.1

Type of HPC? (Box)

-

-

f'c=8,000psi; permeability <2500 coulombs

C.5.2.

Type of HPC? (Slab)

-

max permeability req's

 All concrete used in CIP decks is considered to be HPC via a QC/QA specification

D.1.

Use Keyways Between Boxes?

yes

yes

yes

D.2.

Are they Different from AASHTO?

yes

no

yes

D.2.1.

Any Sketch Attached?

-

-

-

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

yes

no

yes

precast plant

-

before erection at jobsite

D.4.

What Filler Material used?

non shrink grout

Cementituous grout - 770# agg per 220# cement (type II) w/100# max water content

high strength, impact resistant, non-shrink grout

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

no

no

no

-

-

-

D.6.

Any Experience of Water Leakage?

no

no

no

D.7.

When do you Grout Keyways?

after 

before & after - pre-tension, grout, final tension

before

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning

both

pretensioning

low-relaxation - 1/2" dia

low-relaxation - 1/2" dia

low relaxation - 1/2" dia

E.3.

Type of Strand Layout?

straight

combination - straight for pre-tensioning, draped for post-tensioning

combination - straight with debounded & draped

E.4.

Any Unbonded Strands?

no

yes

yes

E.5.

Any Transverse Prestress?

yes

yes - transverse tie

yes

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

bars

bars

strands

-

-

-

E.6.2.

No. of Strands/Tendon?

-

-

-

E.6.3.

Lo w-relaxation or Stress Relieved?

-

-

low-relaxation

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

Missouri

Nevada

New Hampshire

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

1"

1 1/4"

-

 A307 ksi

36 ksi

-

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

mid-depth

mid-depth

one line of post-tensioning - 9" from top, 2 lines of  post-tensioning - 9" from top & bottom

E.8.

Magnitude of Transverse PT?

no - half of what a high strength bolt would be

no - 30k tension

no

E.9. E.9.1.

Spacing of PT Longitudinal

none

-

-

none

-

-

E.9.2.

Transverse

none

ties - 25'

~20'

F.1.

Type of Bearings?

plain & laminated elastomeric

laminated elastomeric

laminated elastomeric

F.1.1.

Type of Laminate?

steel

steel

steel

F.2.

T ype of Lateral Movem ent Restraint?

dowel pins

shear keys or blocks

dowel pins, shear keys or blocks

F.3.

Any Experience with uneven seating?

no

no

yes

F.3.1.

Type of Support?

-

-

full support each end, 3-point support & 4-point support - span & skew dependent

G.1.

Any Lessons, Experiences or Ideas?

no

-

-

G.2.

Any State Standard Drawings?

no

no

no

G.2.1. G.2.2. G.3.a

Any Connection Weldment Dr awing? Any Key Sketch Attached? Name of Contact Person

no

no

no

no

no

no

Suresh Patel

Todd Stefonowicz

Peter Stamnas

G.3.b

Title:

Senior Structural Engineer

Ass't Chief Bridge Engineer

Seniot Project Engineer  

G.3.c

Phone No.

573-526-3030

775-888-7550

603-271-2731

G.3.d

e-mail:

[email protected]

[email protected]

[email protected]

G.3.e

Agency

Missouri DOT

NV DOT

New Hampshire DOT

Additional Comments

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Keyways

Prestressing

New York

A.1

Use Box Beam Bridges?

yes

yes

yes

Location

Highway bridges

Highway bridges

Highway, RR & Pedestrian Bridges

A.3.

Shape of Box?

 AASHTO/PCI & Other

AASHTO/PCI

no

yes

A.4.

Any Skew Angle Limitation?

 AASHTO/PCI - attached please find copy of   AASHTO LRFD Design Manual for bridges & structures guide sheet 3.10-10 yes

A.4.1.

Max. Skew Angle Permitted?

30 degrees

-

-

A.5.

Waterproof or Coat the Sides?

yes - waterproof seal coat

no

yes - all surfaces are coated with penetrating (silane) sealers

A.6.

Any Differential Camber Restr ictions?

no

no

no

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

other - as a result of post-tensioning method, differential camber concerns have been m itigated

other - premeasure camber at precast yard

overlay & other (Shear key grout is sloped from higher to lower to get gradual transition.)

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

recess by melting with torch

cut flush

cut flush

yes

-

-

A.8.2

If yes, with what material?

non-shrink epoxy grout

-

Ends of the cut strands are protected against corrosion

no

no

-

-

A.9.

Box Beam Construction

New Mexico

A.2.

A.9.1

Deck Slab & Overlay

New Jersey

yes Are Ends of Beams Coated? How much of the ends? Patch material over  4ft length at the ends subject to deck joint leakage end of strands only?

A.9.2

With what material? Unspecified waterproofing material?

we specify a two-component, epoxy resin waterproofing system

-

-

B.1.

Use with CIP Composite Deck Slab?

yes

yes

yes

B.1.1

Thickness of Slab?

8", minimum when spread box beams are used

5.5"

150mm (6") minimum. High performance concrete with reinforcement

B.2.

Use Overlay?

yes - overlay used for adjacent configurations

on top of CIP slab & in lieu of CIP slab

no

B.3.

What Type of Overlay?

silica fume concrete & latex modified concrete

asphalt: w/waterproofing membrane

-

B.4.

Thickness of Overlay?

5" minimum

2"

-

C.1.

Type of Void?

polystyrene

Other - we do not specify

polystyrene

C.2

Cast in One-or two Part Placement?

one

one

two

C.2.1.

Monolithic or Cold Joint?

-

-

C.3.

Do you use Hold Downs for Voids?

no

no

monolithic required no - reviewed and accepted by the department not shown in contract plans.

C.4.

Is Hold down sacrificial?

-

yes - designed by precaster

-

C.5.

Use HPC?

no

yes

yes

C.5.1

Type of HPC? (Box)

-

12,000 psi

high strength (70 Mpa) high performance

C.5.2.

Type of HPC? (Slab)

-

-

?

D.1.

Use Keyways Between Boxes?

yes

yes

yes

D.2.

Are they Different from AASHTO?

yes

yes

yes

-

-

 Attached please find copy opf AASHTO LRFD NJDOT Design Manual for Bridges & structures guide plate 3.10-10 and 3.10-12 yes

no

yes

precast plant

-

precast plant

we specify that keyways shall be filled with nonmetallic, non-shrink grout conforming to ASTM C1107 Type A, B or C

standard grout

please see attachment #1

D.2.1.

Any Sketch Attached?

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

D.4.

What Filler Material used?

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

no

no

no

-

-

D.6.

Any Experience of Water Leakage?

no

yes

no - leakage was a problem before the current detail was adopted in 1992

D.7.

When do you Grout Keyways?

after

before

before

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning

pretensioning

pretensioning

low-relaxation - 1/2" dia

low-relaxation

0.6" dia

E.3.

Type of Strand Layout?

straight

straight

straight

E.4.

Any Unbonded Strands?

yes

yes

yes

E.5.

Any Transverse Prestress?

yes

yes

yes

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

strand & bars

bars

strands

-

1/2" dia

E.6.2.

No. of Strands/Tendon?

-

3

E.6.3.

Lo w-relaxation or Stress Relieved?

0.6" dia per design requriement and in conformance with  AASHTO LRFD Bridge Design Specification  Article 5.4.6.2 low-relaxation

-

polystrand tendon

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

E.8.

Magnitude of Transverse PT?

E.9. E.9.1.

Spacing of PT Longitudinal

E.9.2.

Transverse

F.1.

Type of Bearings?

F.1.1.

Type of Laminate?

F.2.

T ype of Lateral Movem ent Restraint?

F.3.

Any Experience with uneven seating?

 Attached please find copy of AASHTO LRFD NJDOT Design Manual for Bridges & Structures guide Sheet 3.10-9 Dowel pins - Attached please find copy of   AASHTO LRFD NJDOT Design Manual for  Bridges & Structures Standard Guide Plate 3-10-4 & 3.10-5 no

F.3.1.

Type of Support?

-

G.1.

New Jersey

New Mexico

New York

1 3/8"

8

-

127.5ksi  Attached please find copy of AASHTO LRFD NJDOT Design Manual for Bridges & Structures Guide Plate 3.10-10 yes - [attached please find copy of AASHTO LRFD NJDOT Design Manual for Bridges & Structures Section 1.25.6 item 3 -

150ksi

-

mid-height

see attachment #2

no

see attachment #3

-

-

2"

?

dependant of situation

?

plain elastomeric

Plain & Laminated elastomeric

-

-

dowel pins

dowel pins

yes

no

full support each end

full support each end

Any Lessons, Experiences or Ideas?

yes - Use of transverse tie post-tensioning works better in controlling differential settlement in adjacent box/slab beam construction

yes - we will change to 3 point support

See attached "full depth shear key" that NYSDOT started using from 1992. Reflective cracking & associated leakage through shear  keys has been eliminated. We still have some deck cracking due to the shrinkage etc.

no

Refer to Guide plates 3.10-13&14 for transverse tie detailing

Plain & Laminated Elastomeric

G.2.

Any State Standard Drawings?

yes

no

G.2.1. G.2.2. G.3.a

Any Connection Weldment Dr awing? Any Key Sketch Attached? Name of Contact Person

no

no

no

yes

no

yes

Ted L. Barber

Mathew Royce

G.3.b

Title:

Bridge Engineer

Associate Civil Engineer  

G.3.c

Phone No.

Harry A. Capers, JR. PE State Bridge Engineer, Manager, Structural Engineering 609-530-2557

505-827-5449

518-457-4534

G.3.d

e-mail:

[email protected]

[email protected]

[email protected]

G.3.e

Agency

New Jersey Department of Transportation

New Mexico State Highway and Transportation Department

NYSDOT

Additional Comments

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Box Beam Construction

Prestressing

Ohio

A.1

Use Box Beam Bridges?

yes

yes - spread boxes only

yes

Location

RR Bridges

Highway bridges

Highway, RR & Pedestrian Bridges

A.3.

Shape of Box?

 AASHTO/PCI

State Standard

State Standard

A.4.

Any Skew Angle Limitation?

yes

yes

yes

A.4.1.

Max. Skew Angle Permitted?

45 degrees

30 degrees

30 degrees

A.5.

Waterproof or Coat the Sides?

no

no

yes - non-epoxy sealer for fascia beams only

A.6.

Any Differential Camber Restr ictions?

-

no

yes - 1/2"

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

overlay

other - do not concern ourselves with this as we don't use abutting beams

overlay

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

recess by melting w/torch

cut flush & burn flush

burn flush

yes

no

n/a

A.8.2

If yes, with what material?

non-metallic, non-shrink grout

-

-

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

yes

no

yes

total area

-

The entire beam ends that are not completely encased in concrete

A.9.2

With what material? Unspecified waterproofing material?

epoxy protective coating

-

One primer coat. Three coats of asphalt material and two layers of waterproofing fabric.

B.1.

Use with CIP Composite Deck Slab?

no

yes

yes

B.1.1

Thickness of Slab?

-

8"

6"

B.2.

Use Overlay?

in lieu CIP slab

no

On top of CIP slab

B.3.

What Type of Overlay?

asphalt: w/waterproofing membrane & other  (asphaltic panels)

-

asphalt w/out waterproofing membrane, silica fume concrete Latex-modified concrete

B.4.

Thickness of Overlay?

1" w/3/32" membrane

-

1 1/4" min

C.1.

Type of Void?

polystyrene

we don't specify type but the lone manufacturer  generally uses polystyrene

Polystyrene

C.2

Cast in One-or two Part Placement?

two

one

Two

C.2.1.

Monolithic or Cold Joint?

monolithic required

-

monolithic required

C.3.

Do you use Hold Downs for Voids?

no

no

no

C.5.

Use HPC?

no

no

no - weight of steel reinforcements on top of the void is sufficient to keep voids at their specified position yes

C.5.1

Type of HPC? (Box)

-

-

-

C.5.2.

Type of HPC? (Slab)

-

-

Micro-silica & fly ash

D.1.

Use Keyways Between Boxes?

yes

-

Yes

D.2.

Are they Different from AASHTO?

no

-

Yes

D.2.1.

Any Sketch Attached?

-

-

yes

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

no

-

yes

-

-

precast plant

D.4.

What Filler Material used?

non-shrink grout

-

nortar

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

no

-

no

-

-

-

D.6.

Any Experience of Water Leakage?

no

-

yes

D.7.

When do you Grout Keyways?

after

-

after

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning

pretensioning

yes

low-relaxation - 1/2" dia

low-relaxation - 1/2"dia & 0.6" dia

no

E.3.

Type of Strand Layout?

draped

draped & straight

straight yes

C.4.

Keyways

North Dakota

A.2.

A.9.1

Deck Slab & Overlay

North Carolina

Is Hold down sacrificial?

yes - threaded rods (removed) bent plates (remains)

-

E.4.

Any Unbonded Strands?

no

yes

E.5.

Any Transverse Prestress?

yes

no

no

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

bars

-

bars

-

-

-

E.6.2.

No. of Strands/Tendon?

-

-

-

E.6.3.

Lo w-relaxation or Stress Relieved?

-

-

-

 

 

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

North Carolina

North Dakota

Ohio

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

#9

-

1" dia

36ksi

-

36 ksi

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

1'-7"

-

top of beam - 9" for beams 17" to 27" deep and 14" for beams 33" to 42" deep

E.8.

Magnitude of Transverse PT?

no

-

no - we specify 250 ft-lbs torque

E.9. E.9.1.

Spacing of PT Longitudinal

-

-

-

2"

-

25'

E.9.2.

Transverse

2"

-

n/a

F.1.

Type of Bearings?

laminated elastomeric

others - we use these in jointless intregal abutment bridge. We set the beams on 1/2" thick preformed  joint filler & cast it in the pier diaphragm & abutment backwall

laminated elastomeric

F.1.1.

Type of Laminate?

steel

-

steel

F.2.

T ype of Lateral Movem ent Restraint?

dowel pins

other - The beams ends are cast ion concrete

dowel pins

F.3.

Any Experience with uneven seating?

no

no

no

F.3.1.

Type of Support?

-

-

-

G.1.

Any Lessons, Experiences or Ideas?

no

yes - We feel that j ointless bridges are the best way to avoid problems with bearings and substructure corrosion

no

yes

G.2.

Any State Standard Drawings?

no

no - enclosed

G.2.1. G.2.2. G.3.a

Any Connection Weldment Dr awing? Any Key Sketch Attached? Name of Contact Person

no

no

no

no

no

yes

Greg Perfetti

Larry Schwartz

Sean Meddles

G.3.b

Title:

State Bridge Design Engineer

Assistant Bridge Engineer

Bridge Engineer  

G.3.c

Phone No.

919-250-4037

701-328-4446

614-466-2464

G.3.d

e-mail:

[email protected]

[email protected]

[email protected]

G.3.e

Agency

North Carolina Department of Transportation

North Dakota Department of Transportation

Ohio Department of Transportation

Additional Comments

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Box Beam Construction

Keyways

Prestressing

Pennsylvania

Rhode Island

A.1

Use Box Beam Bridges?

yes

yes

yes

A.2.

Location

Highway & RR Bridges

Highway, RR & Pedestrian Bridges

highway bridges

A.3.

Shape of Box?

Not familiar w/AASHTO/PCI (see attached drawing)

 AASHTO & State Standard

AASHTO/PCI

yes See standard BD-651M on website www.dot.state.pa.us/bridge/standards

no

A.4.

Any Skew Angle Limitation?

yes

A.4.1.

Max. Skew Angle Permitted?

45 degrees

A.5.

Waterproof or Coat the Sides?

no

yes - at the end of the beam

Yes - Penetrant class sealers

A.6.

Any Differential Camber Restr ictions?

-

-

yes

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

overlay

overlay

overlay & other - (deck slab)

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

Recess by melting w/torch

Recess by melting with torch

recess by melting w/torch

yes

yes

yes

A.8.2

If yes, with what material?

epoxy grout

polymer cement grout

holes are filled w/an approved non-shrink grout

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

no

no

no

-

-

-

A.9.1

Deck Slab & Overlay

Oregon

-

A.9.2

With what material? Unspecified waterproofing material?

-

-

-

B.1.

Use with CIP Composite Deck Slab?

Yes

Yes

yes

B.1.1

Thickness of Slab?

5"

5 1/2" adj, 8" spread

6"

B.2.

Use Overlay?

In lieu of CIP slab

not usually

In lieu of CIP slab

B.3.

What Type of Overlay?

 Asphalt w/waterproofing membrane & silica fume concrete

latex modified concrete

asphalt w/ waterpro ofing membrane

B.4.

Thickness of Overlay?

2" + build-up

1 1/2"

3"

C.1.

Type of Void?

Polystyrene

polystyrene, cardboard

polystyrene one

C.2

Cast in One-or two Part Placement?

two

one

C.2.1.

Monolithic or Cold Joint?

monolithic required

-

-

C.3.

Do you use Hold Downs for Voids?

no

no

yes

C.4.

Is Hold down sacrificial?

C.5.

Use HPC?

(void hold-down system assumed) No-void is held down by bars extending into box to void from forms no

C.5.1

Type of HPC? (Box)

-

C.5.2.

Type of HPC? (Slab)

-

D.1.

Use Keyways Between Boxes?

D.2.

Are they Different from AASHTO?

yes not familiar w/AASHTO/PCI shape (see attached drawing)

D.2.1.

Any Sketch Attached?

-

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

D.4.

What Filler Material used?

D.5. D.5.1.

no yes our typical mixes do have HPC attributesnormally use fc'=8ksi

only on pilot projects

yes - a steel hold down plate is screwed in from form. Upon curing the screw is retrieved and the hole is filled w/grout yes micro silica, 8000-10,000 psi

micro silica, 8000-10,000 psi

yes

yes

see standards

yes

see BC-775M on www.dot.state.pa.us/bridge/standards

-

Yes

yes

no

precast plant

before erection at jobsite

-

non-shrink grout from ODOT QPL. Requires 72hour cure

non-shrink grout

an approved non-shrink grout

Any Welded Connections Used? Any Details attached?

no

no

no

-

-

-

D.6.

Any Experience of Water Leakage?

no

no

yes

D.7.

When do you Grout Keyways?

before

before - grout reaches 2500psi & 48hr - curing time before post-tensioning

before & after - grouting is done afterwards when the skew angle is greater than 30 degrees & the post-tensioning strands are stitched

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

both

Both - but PT was long ago

pretensioning

low relaxation - 1/2" dia

low-relaxation - 3/8" dia, 1/2" dia

low-relaxation - 1/2" dia

E.3.

Type of Strand Layout?

combination - straight & harped

draped, straight, combination - draped & debonding as alternative

draped, straight

E.4.

Any Unbonded Strands?

no

yes

yes

E.5.

Any Transverse Prestress?

yes

yes - only adj

yes

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

bars

strands

strands

-

1/2"

1/2"

E.6.2.

No. of Strands/Tendon?

-

-

1 per sleeve

E.6.3.

Lo w-relaxation or Stress Relieved?

-

low-relaxation

low-relaxation

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

Oregon

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

7/8"

-

-

92ksi (ASTM A449)

-

-

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

mid-height

see shear key detail BC-775M @ www.dot.state.pa.us/bridge/standards

9"

E.8.

Magnitude of Transverse PT?

no - develop adequate friction to resist dead load of beam (ignore contribution from keyway)

no - standard criteria - 1 strand - 30 kips

yes - AASHTO

E.9. E.9.1.

Spacing of PT Longitudinal

-

-

-

strand at 2" centers

2"

2" min

E.9.2.

Transverse

24'

2"

one strand per sleeve

F.1.

Type of Bearings?

plain elatomeric

plain elastomeric, laminated elastomeric & others (pot bearings)

plain & laminated elastomeric

F.1.1.

Type of Laminate?

n/a

steel

steel

F.2.

T ype of Lateral Movem ent Restraint?

dowel pins

dowel pins & shear keys or blocks

dowel pins

F.3.

Any Experience with uneven seating?

no

yes

yes

F.3.1.

Type of Support?

-

full support each end

4-point support

G.1.

Any Lessons, Experiences or Ideas?

-

no

no

G.2.

Any State Standard Drawings?

yes

no - see website

G.2.1. G.2.2. G.3.a

Any Connection Weldment Dr awing? Any Key Sketch Attached? Name of Contact Person

no

no

yes

no

no

Matthew Stucker

Tony McCloskey, P.E.

Michael Savella

G.3.b

Title:

Structural Design Engineer

Civil Engineer Consultant (Bridge)

Principal Civil Engineer  

G.3.c

Phone No.

503-986-3692

717-705-1495

410-222-2053 ext 4080

G.3.d

e-mail:

[email protected]

[email protected]

msavelladot.state.ri.us

Agency

Oregon Department of Transportation - Bridge Engineering Section

PennDOT / Bureau of Design / Bridge Quality  Assurance Division

Rhode Island Department of Transportation

G.3.e

Additional Comments

Pennsylvania

Rhode Island

no - state standards are available on-line @ www.dot.state.ri.us no

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Box Beam Construction

Keyways

Prestressing

Texas

Vermont

A.1

Use Box Beam Bridges?

yes

yes

yes

A.2.

Location

Highway Bridges

Highway, RR & Pedestrian Bridges

Highway Bridges

A.3.

Shape of Box?

 AASHTO/PCI

State standard

State Standard

yes limit on box ends is 60 degrees: no limit on substructure skew

A.4.

Any Skew Angle Limitation?

A.4.1.

Max. Skew Angle Permitted?

A.5.

Waterproof or Coat the Sides?

A.6.

no

Yes

recommend 30 degree max

45 degrees

no

no

Yes - Linseed oil - only on exterior fascias

Any Differential Camber Restr ictions?

yes

-

no

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

we only use side by side boxes w/4.5" concrete overlays. Most applications are spread boxed w/thicker slabs

other - CIP slab

overlay

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

-

cut flush, recess by melting w/torch

burn flush, recess by melting w/torch

-

yes

yes

A.8.2

If yes, with what material?

we extend strands projected into CIP diaphragms & endwalls

epoxy grout

grout

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

A.9.1

Deck Slab & Overlay

Tennessee

no

yes

yes

-

just around strands

over the strands

A.9.2

With what material? Unspecified waterproofing material?

-

epoxy grout

not specified - grout, epoxy

B.1.

Use with CIP Composite Deck Slab?

yes

yes

yes

B.1.1

Thickness of Slab?

4.5" adjacent boxes as req'd for spread boxes

5"

5"

B.2.

Use Overlay?

-

-

on top of the CIP slab, in lieu of CIP slab

B.3.

What Type of Overlay?

other - see question B1 response

-

asphalt w/waterproofing membrane

B.4.

Thickness of Overlay?

see question B1 response

-

2 1/2"

C.1.

Type of Void?

polystyrene

polystyrene & cardboard (only if vented)

Polystyrene one

C.2

Cast in One-or two Part Placement?

two

two

C.2.1.

Monolithic or Cold Joint?

cold joint acceptable

monolithic required

-

C.3.

Do you use Hold Downs for Voids?

yes

yes

yes

C.4.

Is Hold down sacrificial?

yes - various fabricators use different means-most all acceptable

no-but fabricator can propose method and ask for  dept. approval

yes - dependent on precasted

C.5.

Use HPC?

no

yes

yes

C.5.1

Type of HPC? (Box)

-

yes

yes

C.5.2.

Type of HPC? (Slab)

-

yes

yes

D.1.

Use Keyways Between Boxes?

yes

yes

yes

D.2.

Are they Different from AASHTO?

no

yes

yes

D.2.1.

Any Sketch Attached?

-

-

tes

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

no

no

no

-

-

-

as we only use adjacent boxes w/reinforced concrete overlay, the key, if present, is filled w/same mix as the slab

4,000psi slab concrete

site mixed grout no

D.4.

What Filler Material used?

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

yes

no

-

-

-

D.6.

Any Experience of Water Leakage?

-

yes

yes

D.7.

When do you Grout Keyways?

-

-

before

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning

pretensioning

pretensioning

low-relaxation - 1/2" dia

low-relaxation - 1/2" dia

low-relaxation - 1/2" dia, 0.6" dia

E.3.

Type of Strand Layout?

straight

straight

straight

E.4.

Any Unbonded Strands?

yes

yes

yes

E.5.

Any Transverse Prestress?

no

no

yes

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

-

-

strands

-

-

1/2" dia

E.6.2.

No. of Strands/Tendon?

-

-

-

E.6.3.

Lo w-relaxation or Stress Relieved?

-

-

low-relaxation

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category

Bearings

Experience

Item No.

Description

Tennessee

Texas

Vermont

E.6.4. E.6.5.

Size of Bar? Yield Strength of Bar?

-

-

-

-

-

-

E. 7.

L oca ti on of Tr an sv er se PT fr om Bo tt om ?

-

-

typically mid-height

E.8.

Magnitude of Transverse PT?

-

-

no

E.9. E.9.1.

Spacing of PT Longitudinal

-

-

-

2"

2"

E.9.2.

Transverse

-

-

2" +single strand @ ends & midpoint and at times 1/3 points

F.1.

Type of Bearings?

plain elactomeric

Laminated elastomeric

Laminated Elastomeric

F.1.1.

Type of Laminate?

-

steel

Steel

F.2.

T ype of Lateral Movem ent Restraint?

We only use boxes w/strand & mild reinforcement projecting into cip diaphragms & endwalls. No additional lateral restraint needed.

shear keys or blocks

Dowel Pins & Other - anchor bolt device

F.3.

Any Experience with uneven seating?

no

yes

Yes

F.3.1.

Type of Support?

-

3-point support

full support each end & 4-point support

G.1.

Any Lessons, Experiences or Ideas?

yes - comment on F3 above: We get calls periodically from the field that they see gaps between the bearing pad & the bottom of the beam, usually on the wider single pad end of the beam, on yes - For many years, late 50's and through early a 3 pad system. Typically, the gap is on a third to a 60's we used simple span adjacent boxes half of the pad width & is less than 1/16" or so. w/asphalt overlays & minimal transverse tension Usually the beams "settle" into place once the rods. All the bad affects of leakage, keyway composite & non-composite DL are appplied. Even on cases that don't completely relax into place, the deterioration, strand corrosion & non-uniform beam participation, occurred. We have an ongoing pads have always performed satisfactorily. We have program to salvage as many of these as we can by research that tells us that up to 20% "lift-off" is placing continuous overlays of reinforced concret. acceptable, & we know that this occurs regularly on  All new uses are as described above. other types of beam projects where slope mis-match comes into play. Usually the proposed fixes are worse than leaving it as it. Extreme case where bearing stresses are increased beyond concrete bearing capacity are our main concern.

yes - I have found that making the bearing seats match the slope of the normal crown, typically helped with seating the precast units

G.2.

Any State Standard Drawings?

no

yes

G.2.1. G.2.2. G.3.a

Any Connection Weldment Dr awing? Any Key Sketch Attached? Name of Contact Person

no

no

no

no

yes

yes

Edward Wasserman

Jeff Cotham, PE

George W. Colgrove III

G.3.b

Title:

Civil Engineering Director

Fabrication Branch Engineer

Project Civil Engineer  

G.3.c

Phone No.

615-741-3351

512-416-2187

802-828-0049

G.3.d

e-mail:

[email protected]

[email protected]

[email protected]

G.3.e

Agency

Tennessee DOT

TXDOT, Bridge Division, Fabrication Branch

Vtrans (VT Agency of Transportation)

Additional Comments

No weldment details are available, that we feel confident work reliably, except in conjunction with a concrete overlay

yes

SURVEY QUESTIONNAIRE RESPONSE PRECAST PRESTRESSED BOX BEAM BRIDGES Category General

Item No.

Description

Box Beam Construction

Keyways

Prestressing

Canada, Ontario

Canada, Saskatchewan

A.1

Use Box Beam Bridges?

yes

yes

yes

A.2.

Location

Highway Bridges

Highway Bridges

Highway Bridges

A.3.

Shape of Box?

State Standard

AASHTO/PCI & Other

AASHTO/PCI & State Standards

A.4.

Any Skew Angle Limitation?

yes

no

yes

A.4.1.

Max. Skew Angle Permitted?

60 degrees

-

45 degrees

A.5.

Waterproof or Coat the Sides?

no

no

yes - silene

A.6.

Any Differential Camber Restr ictions?

no

no

no

A. 7.

D if fer en ti al C am ber C or rect iv e Act io n?

overlay

we always place a topping slab

-

A.8. A.8.1.

Any Treatment of Strands at Ends? Are Recessed Holes Filled?

cut flush & burn flush

recess by melting with torch

burn flush

-

yes

-

A.8.2

If yes, with what material?

-

bituminous compound

-

A.9.

Are Ends of Beams Coated? How much of the ends? Patch material over  end of strands only?

A.9.1

Deck Slab & Overlay

Canada, Manitoba

yes

yes

yes

2" past strands

just the end face

area of strands

A.9.2

With what material? Unspecified waterproofing material?

zinc-rich paint or waterproofing material

bituminous paint

Bakor 10-11

B.1.

Use with CIP Composite Deck Slab?

yes - rehabilitation & no - new

yes

Yes

B.1.1

Thickness of Slab?

6" - rehab

150mm

200mm

B.2.

Use Overlay?

In lieu of CIP slab (new Bridge)

on top of CIP slab

on top of CIP slab

B.3.

What Type of Overlay?

asphalt w/waterproofing membrane & protection board, silica fume concrete

asphalt w/waterproofing membrane

 Asphalt - w/waterproofing membrance & silica fume concrete

B.4.

Thickness of Overlay?

new bridges - 3" asphalt overlay: rehabilitation - "

90mm waterproofing & asphalt

80 mm asphalt

C.1.

Type of Void?

Polystyrene - void form material not specified but polystyrene is typically used

polystyrene

Cardboard

C.2

Cast in One-or two Part Placement?

two

-

Two

C.2.1.

Monolithic or Cold Joint?

monolithic required

-

Monolithic required

C.3.

Do you use Hold Downs for Voids?

yes

no

Yes

C.4.

Is Hold down sacrificial?

yes - silica ties into stressing bed

no specific requirement

no

C.5.

Use HPC?

yes

yes

Yes

C.5.1

Type of HPC? (Box)

silica fume concrete

-

-

C.5.2.

Type of HPC? (Slab)

-

yes

Silica Fume

D.1.

Use Keyways Between Boxes?

Yes

yes

No

D.2.

Are they Different from AASHTO?

Yes

-

-

D.2.1.

Any Sketch Attached?

yes

-

-

D.3. D.3.1.

Are Keyways sandblasted? Where is Sandblasting Done?

no

no

-

-

-

-

D.4.

What Filler Material used?

non-shrink grout - 4.0 Mpa at 28 days

non-shrink grout

-

D.5. D.5.1.

Any Welded Connections Used? Any Details attached?

yes - for skews 70 degress and less

no

-

D.6.

Any Experience of Water Leakage?

yes

yes

yes

D.7.

When do you Grout Keyways?

after

before

-

E.1. E. 2.

Type of Prestressing? T yp e o f St ran ds fo r L on g. Pr est ressi ng ?

pretensioning

pretensioning

pretensioning

low-relaxation - 1/2" dia

low-relaxation - 1/2" dia

Low-relation - 3/8", 1/2" & 0.6" dia

E.3.

Type of Strand Layout?

harped

combination - straight & draped

straight

E.4.

Any Unbonded Strands?

yes

yes

yes

E.5.

Any Transverse Prestress?

yes

no

no

E.6. E.6.1.

Transverse PT Type & Size? Size of Strand?

strands

-

-

1/2"

-

-

E.6.2.

No. of Strands/Tendon?

12-15 strands per span

-

-

E.6.3.

Lo w-relaxation or Stress Relieved?

low-relaxation

-

-

yes

-