Background and Discussion PCI DESIGN HANDBOOK PRECAST AND PRESTRESSED CONCRETE
7th Edition PCI Industry Handbook Committee
Prepared by PCI Industry Handbook Committee
Greg Force, P.E., FPCI, Chairman Neal S. Anderson, P.E., S.E., FPCI, FACI Ned M. Cleland, PhD, P.E., FPCI, FACI Harry A. Gleich, P.E., FPCI, FACI Gary A. Householder, Househol der, P.E. P.E. Pat Hynes, P.E., FPCI Phillip J. Iverson, P.E. Walter Korkosz, P.E., S.E. Jason Krohn, P.E. P.E. Karen Laptas, P.E. David J. Larsen, P.E., S.E Jason P. Lien, P.E. Rafael A. Magana, M agana, P.E. Michael I. Owings, P.E., S.E. Stephen Pessiki, PhD, FPCI, FACI Steven H. Peterson, P.E. Courtney B. Phillips, P.E., S.E. Timothy R. Salmons, P.E., S.E. Kim E. Seeber, P.E., P.E., FPCI Larbi Sennour, PhD, P.E., P.E., FPCI, FPCI , FACI a Fattah Shaikh , PhD, P.E., FPCI Irwin J. Speyer, P.E., P.E., FPCI, FPCI , FACI Peter G. Troiani, Troiani, P.E., S.E. Helmuth Wilden, P.E., FPCI Charles E. Wynings, P.E. P.E. a. Deceased January 10, 2008
Consulting Members Robert F. Mast, P.E., P.E., S.E., FPCI, FP CI, HACI Jagdish C. Nijhawan, P.E., FPCI J. Robert Norris, P.E.
Foreword The Precast/Prestressed Concrete Institute (PCI) updates and publishes the PCI Design Handbook: Precast and Prestressed Concrete1 in cycles coincident with publication o the American Concrete Institute’s (ACI’s) (ACI’s) Building Code Requirements or Structural Concrete (ACI 318-05) and Commentary (ACI 318R-05) .2 The seventh edition o the PCI Design Handbook , published in 2010, continues that tradition. Each update o the PCI Design Handbook
reects the modifcations adopted by ACI 318 as well as the most recent research and experience o designers regularly engaged in the design o precast and prestressed concrete structures.
Introduction The publication o the seventh edition o the PCI Design Handbook continues to meet the goals set orth by the Precast/Prestressed Concrete Institute, which was established in 1954 as the Prestressed Concrete Institute. The current name was adopted in 1989 to better reect the interests o both prestressed concrete producers and those that manuacture nonprestressed precast concrete components. The goal is to advance the design, manuacture, and use o precast and prestressed concrete. The seventh-edition PCI Design Handbook ’s ’s primary objective remains the same as it was with the frst edition, published in 1971; that is, “… to make it easier or architects and engineers to use prestressed and precast concrete. It is intended to be a working tool, assisting the designer in achieving optimum solutions in minimum time.”
Editor Helmuth Wilden, P.E., FPCI
The seventh edition o the PCI Design Handbook background and discussion paper is the sixth document o i ts type. The frst was published or the second-edition PCI
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Design Handbook and was an authored paper titled “Background and Discussion on PCI Design Handbook , Second
Edition.” It was published in the January–February 1980 issue o the PCI Journal. Subsequent papers with the same intent and similar titles were published as ollows: •
•
•
For the third-edition PCI Design Handbook : May– June 1988, PCI Journal For the ourth-edition PCI Design Handbook : November–December 1996, PCI Journal •
•
For the fth-edition PCI Design Handbook : July–August 1998, PCI Journal •
•
For the sixth-edition PCI Design Handbook : March– April 2006, PCI Journal •
Purpose The main purpose o the background and discussion o the seventh edition o the PCI Design Handbook is to identiy signifcant changes rom the sixth edit ion on a chapter-bychapter basis and explain the rationale or these changes. Other purposes are to describe current work in progress toward the eighth edition o the PCI Design Handbook and to establish goals or uture work.
Synopsis of changes from the sixth-edition PCI Design Handbook
Table 1 outlines the dierences rom the sixth edition to the seventh edition o the PCI Design Handbook .
The seventh edition o the PCI Design Handbook , while similar to the sixth edition in many ways, incorporates modifcations that generally all into one o the ollowing categories: •
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It includes updated inormation reecting changes rom ACI 318-02 to ACI 318-05, incorporating new and revised provisions. Note that changes related to ACI 318-08 are identifed in the appendix to the seventh edition.
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It includes updated inormation based on current standard practices o the industry. It includes updated inormation based on results o recent research in the industry. It expands text o selected topics t o provide morecomprehensive discussion. Selected text, fgures, tables, Design Aids, and examples are rewritten, modifed, and edited or improved clarity.
The user o the PCI Design Handbook will observe several somewhat subtle dierences rom the sixth edition: •
•
•
Some things in the seventh-edition PCI Design Handbook remain unchanged rom the sixth edition. The number o chapters has been increased rom 11 to 15 as a result o the PCI Industry Handbook Committee’s intent to provide more emphasis on some topics, including fre endurance and vibrations. Chapter 9, Precast and Prestressed Concrete: Materials, is totally new and compiles discussions o materials that were in individual chapters in previous editions. Chapter 2 is also totally new and includes the notation used throughout the entire handbook on a chapter-by-chapter basis.
It incorporates comments by the sixth-edition PCI Design Handbook Blue Ribbon Review Committee that could not be included in the sixth edition.
• •
It includes the correction o errors in the sixth edition that were published as errata in the May–June 2007 issue o the PCI Journal.
•
•
•
•
Equations are numbered consecutively in e ach chapter. For example, Eq. 6.5.2.1 in the sixth edit ion is now Eq. (6-2) and Eq. 6.12.1.1 is now Eq. (6-93). A complete list o design examples is included at the end o the oreword to the handbook. Previous charts shown as fgures are now Design Aids, and a complete list is included at the end o the oreword to the handbook. All fgures and tables are identifed with a three-digit number. For example, Table 6.6.5.2 in the sixth edition is now Table 6.6.3 and Fig. 6.7.3.1 is now Fig. 6.7.1. The frst digit reers to the chapter, the second digit reers to the main section in which the fgure or table appears, and the third digit represents the consecutive order in the main section. Chapters are identifed on each page with a tab box at the edge o the page or easy reerence. The term member , representing a precast concrete unit, has been changed to component throughout the handbook. This was done to be consistent with the title or chapter 5 o the seventh-edition PCI Design Handbook . For the most part, American Concrete Institute nomenclature and ormatting has been used.
The user will also observe that some sections o the sixth edition have been omitted rom the seventh edition. They are:
Table 1. Comparison o 6th and 7th editions o the PCI Design Handbook Sixth edition
Chapter
Pages
Figures
1
32
58
Design Aids
Pages
Figures
Tables
Design examples
Design Aids
5
n.a.
n.a.
28
63
n.a.
n.a.
n.a.
New
n.a.
n.a.
n.a.
n.a.
n.a.
18
n.a.
n.a.
n.a.
n.a.
3
Ch. 2 in 6th
58
8
32
n.a.
8
64
8
32
n.a.
11
4
Ch. 3 in 6th
124
20
2
19
26
98
34
4
13
26
5
Ch. 4 in 6th
132
25
8
43
14
152
38
8
48
15
6
102
39
5
23
15
116
39
11
26
14
7
22
15
3
n.a.
n.a.
36
18
4
3
n.a.
8
Ch. 5 in 6th
36
27
4
6
n.a.
28
27
4
4
n.a.
9
New
n.a.
n.a.
n.a.
n.a.
n.a.
42
22
10
n.a.
n.a.
10
Sect. 9.3 in 6th
26
19
13
5
n.a.
26
17
13
4
n.a.
11
Sects. 9.1 and 9.2 in 6th
23
4
15
4
n.a.
26
4
15
4
n.a.
12
Sect. 9.7 in 6th
8
2
3
3
n.a.
10
2
3
3
n.a.
13
Ch. 8 in 6th
34
6
13
2
n.a.
34
6
11
2
n.a.
14
Ch. 10 in 6th
36
n.a.
n.a.
n.a.
n.a.
36
n.a.
n.a.
n.a.
n.a.
15
Ch. 11 in 6th
58
n.a.
n.a.
n.a.
31
62
n.a.
n.a.
n.a.
37
New
n.a.
n.a.
n.a.
n.a.
n.a.
22
6
8
n.a.
n.a.
691
223
103
105
94
776
278
115
107
103
Totals
•
Design examples
Tables
2
Appendix
•
Seventh edition
Section 9.5, Quality Assurance and Control. The committee elt that this section was redundant because three major PCI quality-control manuals already exist. They are MNL-116 3 or structural precast concrete, MNL-1174 or architectural precast concrete, and MNL-1305 or glass-fber-reinorced concrete. Section 9.9, Precast Segmental Construction. This topic is outside the area o building construction, which is the emphasis o the handbook, and more up-to-date
inormation is available in other publications. •
Section 9.10, Coordination with Mechanical, Electrical and Other Sub-Systems. At the time o publicati on o the seventh edition, it was the i ntent o PCI to develop a recommended practice and guidelines or tota l precast concrete structures and the committee considered that this new publication would provide more inormation than could be included in the handbook.
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The handbook committee process It is o interest to review the process by which the seventh edition o the PCI Design Handbook was created. As soon as the sixth edition was published in 2004, a new Industry Handbook Committee was established. It consisted o 25 ull members and 3 consulting members. Eighteen o these people served on the previous sixth-edition committee. They represent various interests within the industry and include 15 specialty engineers, 9 plant engineers, 2 tradeassociation engineers, and 2 academics. The process used was as ollows: 1.
2.
The committee agreed on a new arrangement, increasing the number o chapters rom 11 to 15, as described later in this article.
3.
A subgroup o three to seven members (including a chairperson) was established or each chapter. The objective o each chapter subgroup was to perorm a detailed review o the existing chapter and an exhaustive review o research and publications rel evant to the subject o the chapter subsequent to the sixth edition.
4.
5.
6.
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The committee used the sixth edition as the baseline, with the understanding that ACI 318-05, American Society o Civil Engineers (ASCE) 7-05, 6 and International Building Code 2006 (IBC 2006)7 would be the relevant reerences or the seventh edition.
Ater analysis o inormation discovered in the subgroups’ reviews and discussion regarding i mproved and/or updated content, each subgroup developed a drat o its respective chapter. Each chapter was then edited by the editor, and a committee-ballot version was created. Each chapter was balloted by the committee, and all comments were resolved during meetings o the ull committee. This process included 14 ace-to-ace meetings and 9 web-based teleconerences over the our-year course o development. The intensity peaked during 2009 with two ace-to-ace meetings and all nine o the teleconerences. In addition, hundreds o individual telephone calls and thousands o emails between members and to and rom the editor took place.
7.
Additional editing was done, and a Technical Activities Council (TAC) ballot version was created.
8.
Each chapter was balloted by TAC with resolution o all comments by both TAC and the Industry Handbook Committee.
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9.
Based on these approved versions, a blue-ribbon-review version was created. This fnal review phase consisted o the Blue Ribbon Review Committee, made up o plant engineers, specialty engineers, consulting engineers, academics, and associate members. Each member o the Blue Ribbon Review Committee is a recognized leader in the analysis and design o precast and prestressed concrete structures or an expert in a closely related feld. The members o the Blue Ribbon Review Committee are noted in the oreword to the handbook. Ater a six-week review period, this group met or three days and oered valuable comments that were considered by the Industry Handbook Committee. Most were accepted as improving the publication. Others will be considered as new business or the eighth edition.
10. A fnal version o each chapter was then created and reviewed thoroughly by the original chapter subgroup. This review resulted in a ew corrections and urther improvement. 11. In addition, a comprehensive editorial and technical review o the handbook was carried out by the PCI Publications Department, led by Emily Lorenz, editorin-chie o the PCI Journal, as well as Jason Krohn, PCI’s Managing Director o Technical Activities. It is commendable that the seventh edition o the PCI Design Handbook was created primarily through the volunteer eorts o the committee members and many others. Thousands o hours were devoted to its development, which, at normal consulting rates, would easily exceed a value o $2 million. The ollowing presents a chapter-by-chapter review o the contents, outlining the general content and emphasizing changes rom the sixth edition as well as the rationale behind these changes.
Chapter 1—Precast and Prestressed Concrete: Applications This chapter is intended to provide the user o the handbook with a general understanding o the many applications o precast and prestressed concrete used in buildings and other structures. (For bridges, a separate publicat ion by PCI, the Precast Prestressed Concrete Bridge Design Manual,8 should be consulted.) As is typical with each new edition o the PCI Design Handbook , the photographs have been updated to illustrate the current state o the art. As a result o the newer photographs, captions and text reerring to the photographs have been updated. Although the handbook is not intended or bridges, a photograph o the Walnut Lane Memorial Bridge ( Fig. 1) has been retained to remind the user o the beginning o
the prestressed concrete industry in the United States. For additional inormation related to the history o the industry, reer to Reections on the Beginnings o Prestressed Concrete in America,9 published in 1981, and PCI Visions Taking Shape,10 published in 2004. These documents commemorate the 25th and 50th anniversaries o PCI, respectively. The sixth-edition fgure o typical products has been replaced with a collage o photographs to better illustrate the variety o products available ( Fig. 2). Because o the growing emphasis on sustainability, section 1.1.3, “Sustainability and LEED Considerations,” has been added to describe the benefts o precast and prestressed concrete in achieving long-lasting and energy-efcient structures.
Figure 1. Walnut Lane Memorial Bridge.
A new section 1.2.1.7, Educational Facilities, has been added to better illustrate the importance o these applications and to present to the user o the handbook the superior solutions that precast and prestressed concrete oers to the owners o these acilities.
stairs, and section 3.3.12 and Design Aid 3.12.11, which provides guidelines for stadium riser sections. Design Aid 3.12.7 has been added to assist in preliminary sizing of non-load-bearing wall panels.
The sixth-edition section 1.3, Materials, was completely removed rom chapter 1. It was extensively expanded and has become the new chapter 9 o the PCI Design Handbook , seventh edition. See the discussion in this article on chapter 9 or urther details o the changes and additions on the subject o materials.
Chapter 4—Analysis and Design of Precast/ Prestressed Concrete Structures
Chapter 2—Notations
The chapter on the analysis and design o precast and prestressed concrete structural systems has been updated to reect the requirements o ACI 318-05, IBC 2006, and ASCE 7-05. There has been an update o the discussion on precast concrete lateral systems, which reects the more-severe treatment in ASCE 7-05 o cantilevered column systems.
This chapter is completely new and includes the notations or the entire handbook. This is the result o the PCI Industry Handbook Committee’s intention to make the handbook similar to ACI 318-05. It was the original intention to include defnitions in this chapter, but the committee considered it more user riendly to include defnitions either at the beginning o each chapter or in the text where a term is used. It is important to recognize that notations identical to those used in ACI 318-05 are identifed wi th “(ACI)” ater the defnition.
Chapter 3—Preliminary Design of Precast/Prestressed Concrete Structures This chapter was chapter 2 in the sixth edition. The load tables in the chapter have been updated to meet the latest ACI 318-05, IBC 2006, and ASCE 7-05 provisions. Load capacities have not changed signicantly, except for short-span components where reduced phi factors φ in the prestressed transfer zone govern the design. Preliminary Design Aids for several new products have been added to the seventh edition, including section 3.3.11 and Design Aid 3.12.10 for use in sizing precast concrete
This chapter was chapter 3 in the sixth edition.
The ASCE 7-05 update or seismic systems includes an alternate equation or the determination o the approximate building period or shear-wall structures. The change to the requirements and actors or redundancy or high-seismic design categories is discussed. The discussion o recommended loads or diaphragm design has been updated in an eort to clariy the dierence between a diaphragm overstrength actor Ψ and the system overstrength actor Ω0. The new, more prescriptive requirement or a positive horizontal connection orce parallel to supported components in ASCE 7-05 section 12.1.4 is discussed as part o updated inormation on structural integrity. Some advanced results rom the PCI-sponsored volumechange study have also been included. 11 The design examples or moment-resisting rames are covered in more detail in the PCI Seismic Design Manual,12 published in 2007, and are no longer repeated in the handbook.
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a
b
c
d
f
e
g
h
Figure 2. Typical products o the industry.
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Figure 3. Collector orce demand diagram or shear walls in a parking garage. See note a in Postpublication Notes at the end o this article.
Examples or shear-wall buildings and or precast concrete diaphragms have been updated to clariy diaphragm and collector design procedures. Diaphragm design has been expanded, and more detail is provided or collectors.
Figures 3 and 4 illustrate the intent o ASCE 7-05 and IBC 2006.
An entirely new section (section 4.9) on blast-resist ant design has been added to the chapter. This section discusses the special considerations o large-magnitude,
Figure 4. Perspective view o shear wall and collectors.
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Table 2. Recommended shear-riction coecients (6th edition) Crack interface condition
Recommended µ
Maximum µe
Maximum V u = φV n
1. Concrete to concrete, cast monolithically
1.4 λ
3.4
2. Concrete to hardened concrete, with roughened surace
1.0 λ
2.9
0.25 λ2f ' c A cr ≤ 1000 λ2 A cr
3. Concrete to concrete
0.6 λ
2.2
0.20 λ2f' c A cr ≤ 800 λ2 A cr
4. Concrete to steel
0.7 λ
2.4
0.20 λ2f ' c A cr ≤ 1000 λ2 A cr
0.30 λ2f ' c A cr ≤ 1000 λ2 A cr
Table 3. Recommended shear-riction coecients (7th edition) Case
Crack interface condition
µa
Maximum µe
Maximum V u /φ
1
Concrete to concrete, cast monolithically
1.4 λ
3.4
0.30 λf' c A cr ≤ 1000 λ A cr
2
Concrete to hardened concrete, with roughened surace
1.0 λ
2.9
0.25 λf' c A cr ≤ 1000 λ A cr
3
Concrete placed against hardened concrete not intentionally roughened
0.6 λ
Not applicableb
0.20 λf ' c A cr ≤ 800 λ A cr
4
Concrete to steel
0.7 λ
Not applicableb
c
0.20 λf ' c A cr ≤ 1000 λ A cr
a. In accordance with ACI 318-05 Section 11.7.4.3. b. The use o µe is not applicable or concrete placed against hardened concrete not intentionally roughened or against steel. c. The handbook shows this as 0.30 λf ' c A cr ≤ 1000 λ A cr . This is incorrect. It should be 0.20 λf ' c A cr ≤ 1000 λ A cr .
short-duration loads on precast concrete systems wit h large mass and inertia. Topics include blast loads, dynamic material properties, and blast-design methods. A blast-design example or a cladding panel is also included.
Chapter 5—Design of Precast and Prestressed Concrete Components This chapter was chapter 4 in the sixth edition. Section 5.2.3 and example 5.2.3.2 have been revised to allow for the use of an interpolated phi factor φ for underdeveloped strand in accordance with ACI 318-05 section 12.9.1. This section and the example show that for the exural analysis of a section with fully and partially developed strand, the partially developed strands will maintain their load when strained beyond the slipping strain. See note b in Postpublication Notes at the end of this article. Section 5.2.5 has been signicantly expanded to increase design guidelines and provide a complete design example for stadium-seating components. 13
Based on a review of the original research, section 5.3.6 has been revised to correct the equation for the effective shear friction coefcient (Eq. [5-33]) to include the phi factor φ in the numerator. Also, based on this review of
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the original research, use of the effective coefcient of friction with concrete placed against hardened concrete not intentionally roughened and concrete-to-steel interfaces has been disallowed, and the formulas for maximum shear stress (right column of Table 4.3.6.1 in the sixth edition) have been revised to remove the squared from the lambda λ terms. Other sections using shear friction have been updated to be consistent with these revisions. A comparison of the sixth-edition and seventh-edition tables is shown in Tables 2 and 3. Based on recent experience with self-consolidating concrete (SCC) in which the surface remained slick after curing, a warning has been included regarding selection of the appropriate interface condition when corbels are cast on the up face of components cast using SCC. In section 4.5 of the sixth edition, Beams with Ledges, the table for ledge design m factors has been removed because the committee felt that solving Eq. (5-52) of the seventh edition is as easy as looking up a value for m in the chart. Also, Fig. 5.5.3 includes corrections for determining the m factor for an inverted-tee beam based on the original research.14
Concerns raised by PCI Professional Members suggested the need for better clarity of the detailing requirements for dap-ended members. Accordingly, the committee modied Fig. 5.6.3 by enlarging the alternative dap reinforcement detail to clarify and emphasize the importance of dap rein forcement detailing and placement.
Chapter 6—Design of Connections
Section 5.8, Camber and Deection, was expanded, primarily to provide guidance for the use of ACI 318-05 Table 9.5(b) Maximum Permissible Computed Deections ( PCI Design Handbook Table 5.8.1).
Tables 4 and 5 (Tables 6.2.1 and 6.2.2 in the seventhedition PCI Design Handbook ) have been added to clariy overstrength actors applicable or diaphragms and collector systems, respectively.
Section 5.9, Compression Components, contains several signicant revisions. In section 5.9.1, the section allowing elimination of lateral ties in certain instances based on Recommended Practice for the Design of Prestressed Concrete Columns and Walls 15 has been removed because the reference no longer contains these exceptions.
Section 6.4.3.1, Reinorcing Bars in Conduit, has added requirements or supplemental reinorcement based on the previous research.18
In Example 5.9.1.1, the interaction curve has been modied to better show its actual shape. In Example 5.9.3.1, the stiffness-reduction factor has been changed to Φ K = 0.85, as suggested by ACI 318-05 section R10.11.1.
Section 6.2.3 has been added to dierentiate IBC 2006 requirements rom recommended PCI values or seismic overstrength actors or lateral-orce-resisting systems.
Table 6.5.5, Summary table o HCA (headed concrete anchors) group concrete shear strength equations, has been added to conveniently show the appropriate design actor or each ailure mode. Design Example 6.5.5.4, Design o Bearing Seat with Headed Concrete Anchors (Example 6.5.8.1 in the sixth edition), has been modifed to include the weld requirements or the bearing seat, and a table has been added that shows all o the component design strengths.
Section 5.9.4, Concrete Brackets or Corbels, has been moved into this chapter from chapter 6, Design of Connec tions, in the sixth edition, on the basis that this is part of the component design rather than a connection.
Further explanation o the interaction o tension and shear or headed concrete anchors has been added to section 6.5.8, Interaction o Tension and Shear.
Section 5.10, Shear Walls, is a completely new section. It provides an introduction to the design of precast concrete shear walls, including a design example.
Examples 6.6.5.1(a) and 6.6.5.1(b) are new and illustrate the design procedure or an unstiened connection angle using headed concrete anchors and bolts, respectively.
Section 5.11, Sandwich Panels, was moved into this chapter from chapter 9 of the sixth edition, Thermal, Acoustical, Fire and other Considerations, because it is an important aspect of many precast concrete structures and is more ap propriate with a discussion about component design.
Section 6.7.2.1, Fillet Welds, has been modifed to more accurately represent the nominal design strength o a fllet weld element. This section now includes the eect o the angle o loading with respect to the axis o the weld element.
Section 5.12.1, Point Loads on Double-Tee Flanges, is a new section, though the design example was in the Analysis Using Strain Compatibility subsection of the Flexure section of the sixth edition. Determination of the effective resisting width for a point load has been revised to more accurately reect load test data. 16
Enhancement has been added to the Instantaneous Center Method (ICM) or weld design in section 6.7.5.2 t o more clearly demonstrate the design approach.
Section 5.12.7, Warping of Deck Components, is a com pletely new section. It addresses the warping of doubletees, especially in parking structures, to obtain desired drainage patterns. Recommendations are based on experience and relatively recent research. 17 Design Aid 5.14.15 now provides updated corbel capacities and more clearly illustrates whether the capacity is limited by exure, shear, or maximum V u.
Chapter 5 modifed the calculation o eective shear riction, and this revision has been applied to the chapter 6 design examples, where appropriate. Cazaly Hanger, section 6.9.1, has been modifed to reect recent research indicating that previous editions may not have been adequately conservative. While the procedure is essentially the same, an additional requirement or anchor reinorcement has been introduced to avoid a concrete breakout ailure (Fig. 5). This is illustrated below.
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Table 4. Diaphragm overstrength actorsa Seismic design category
Ψ factor table design element A
B
C
D
E
F
Bearing-wall systems
1
1
2.5 a
2.5a
2.5a
2.5a
Building-rame systems
1
1
2.5a
2.5a
2.5a
2.5a
Moment-resisting systems
1
1
2.5 a
3a
3a
3a
Dual system with special moment rames
1
1
2.5 a
2.5a
2.5a
2.5a
Dual system with intermediate moment rames
1
1
2.5a
2.5a
2.5a
2.5a
Inverted pendulum system and cantilevered-column systems
1
1
2.5a
2
2
2
Bearing-wall systems
1
1
1b
2
2
2
Building-rame systems
1
1
1b
2
2
2
Moment-resisting systems
1
1
1b
1
1
1
Inverted-pendulum system and cantilevered-column systems
1
1
1b
1
1
1
Bearing-wall systems
1
1
1b
2
2
2
Building-rame systems
1
1
1b
2
2
2
Moment-resisting systems
1
1
1b
1
1
1
Inverted-pendulum system and cantilevered-column systems
1
1
1b
1
1
1
Diaphragm to SFRS connection
Diaphragm chord element
Diaphragm joint shear connection
a. The tabulated value o the diaphragm overstrength actor Ψ may be reduced by subtracting 0.5 or structures with fexible dia phragms but shall not be taken as less than 2.0 or any structure. b. For seismic design category C diaphragms, it has been assumed that the maximum distributed design orce at that l evel is used.
Section 6.13, Typical Connections, has been added to represent typical connection details used in total precast concrete structures. Example 6.13.6, Wall-to-Wall Shear Connection with Combined Loading, is new and illustrates a combined shear and tension connection and the interaction equations or each component and the capacity region o the assembly. Example 6.13.8, Deormed Bar or Reinorcing Bar Connection Plate Supporting Steel Beam, is new and illustrates a typical connection or a steel, wide-ange beam connected to a plate with deormed bar anchors. See note c in Postpublication Notes at the end o this article. Design Aids 6.15.4 and 6.15.5 no longer show weld size and minimum plate thickness requirements or welds using E70 electrodes or ASTM Grade 60 reinorcing bars because this is no longer allowed by AWS D1.4. 19
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Table 5. Seismic overstrength actorsa Seismic design category
Ω o factor table design element A
B
Cb
Db
Eb
Fb
Bearing-wall systems
1
1
2.5
2.5
2.5
2.5
Building-rame systems
1
1
2.5
2.5
2.5
2.5
Moment-resisting systems
1
1
3
3
3
3
Dual system with special moment rames
1
1
2.5
2.5
2.5
2.5
Dual system with intermediate moment rames
1
1
2.5
2.5
2.5
2.5
Inverted-pendulum system and cantilevered-column systems
1
1
1.25
1.25
1.25
1.25
Bearing-wall systems
1
1
2.5
2.5
2.5
2.5
Building-rame systems
1
1
2.5
2.5
2.5
2.5
Moment-resisting systems
1
1
3
3
3
3
Dual system with special moment rames
1
1
2.5
2.5
2.5
2.5
Dual system with intermediate moment rames
1
1
2.5
2.5
2.5
2.5
Inverted-pendulum system and cantilevered-column systems
1
1
1.25
1.25
1.25
1.25
Collectors (drag-ties)
Collectors (drag-tie) transfer to vertical resisting element
a. Table shown is condensed rom ASCE 7-05, Table 12.2-1. b. The tabulated value o the system overstrength actor Ωo may be reduced by subtracting 0.5 or structures with fexible di aphragms but shall not be taken as less than 2.0 or any structure.
Figure 5. Cazaly hanger.
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Figure 6. Cladding panel connection concepts—seismic drit eect (translating panels).
Chapter 7—Structural Considerations for Architectural Precast Concrete
— Example 7.5.3.1, Architectural Precast Concrete Panel with Earthquake Loading. This example is the same as Example 3.2.4.2 in the sixth edition, but has been expanded to reect appropriate seismic actors. It includes comparisons o critical loads rom the two previous wind-load examples to illustrate the actual design procedure that an engineer would use.
This chapter is very much like its counterpart in the sixth edition, with several noteworthy additions: •
•
It includes material rom the third edition o PCI’s Architectural Precast Concrete,20 published in 2007, that is particularly important or a structural engineer designing architectural precast concrete to know. Three examples have been added. All three use the same cladding panel on the same building but consider dierent load conditions. The load cases are: — Example 7.5.1.1, Use of ASCE 7 Method 1 for Wind-Load Determination. This is an extension o Example 4.2.3.1, which uses ASCE 7-05 to calculate wind loads on a building to design or the lateral-load-resisting-system. The example in this chapter covers the individual panels as a cladding component. — Example 7.5.2.1, Use of ASCE 7 Method 2 for Wind-Load Determination. This example was added because Method 1 has a building height restriction o 60 t (18 m) and many architectural cladding components are used on taller buildings.
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•
•
Seismic drit considerations have been added to illustrate the need or some connections to move in dierent directions to avoid unintended orces acting on the cladding and/or the supporting structure. This is illustrated in Fig. 6. The chapter has added recommendations or where to locate connections on cladding panels to provide predictable behavior. This is illustrated in Fig. 7.
Chapter 8—Component Handling and Erection Bracing This was chapter 5 in the sixth edition. The new section 8.3.3, Spreader Beams, has been added to provide guidance or the design o spreader beams used in handling precast concrete components. Section 8.6, Erection Handling, has been revised to address uncontrolled rolling when erecting wall panels with three-point pick using rolling blocks between the two bottom liting points. Some erectors and engineers have
Figure 8. Stability during erection.
Figure 7. Typical cladding connection locations.
observed frsthand that the equation shown in Fig. 5.6.2 o the sixth edition or the distance rom the lower rolling block to the center o gravity is incorrect. This is shown in Fig. 8. A paper written by Don Logan, P.E., in the Winter 2010 PCI Journal21 explains in detail the potential risks associated with using this equation. As a result, the Industry Handbook Committee has recommended the rigging arrangement illustrated in Fig. 9 to avoid this condition. Section 8.7, Erection Bracing, was reduced to an abbreviated version, and design examples were removed. This was a topic that was debated signifcantly by the Industry Handbook Committee, primarily as a result o the dierence between the experiences o the committee members and the requirements o ASCE 37-02 Design Loads on Structures During Construction.22 It was concluded that because ASCE 37-02 is not a mandatory code, the loads imposed on precast concrete structures during erection should be the responsibility o the experienced precast concrete designer. With that responsibility must go the authority t o defne the loading requirements during this temporary stage.
Chapter 9—Precast and Prestressed Concrete: Materials Chapter 9 is a new chapter dealing exclusively with materials aecting and used in precast and prestressed concrete construction. Chapter 9 represents a consolidation o several material sections that were contained in various chapters o past handbook editions. Major topics include concrete, grouts, connection materials, corrosion protec-
Figure 9. Stability during erection.
tion, reinorcement, waterproofng, and in-service repairs. The chapter also includes a number o new fgures, graphs, and tables to augment the text. Because the handbook is oten used as a textbook at the university level and many students have not been exposed to typical materials used in the industry, several photographs have been included—or example, prestressing strand (Fig. 10) and standard reinorcement ( Fig. 11). Section 9.2, Concrete, covers the constituent materials o the concrete matrix, consisting o cement, supplementary cementitious materials (SCMs), aggregates, admixtures, and pigments. Detailed descriptions are provided with relevant reerences to ASTM standards. Physical properties o concrete are introduced, such as compressive and tensile strength, modulus o elasticity, volume changes, and durability. Tables presenting common material parameters are given and photographs o good concrete and common deterioration mechanisms are presented, as illustrated in Fig. 12 and 13, respectively.
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Figure 10. Wire prestressing strand o various sizes. Figure 13. Planar cracking marking reezing and thawing damage.
viding protection against deterioration are covered within the context o waterproofng with coatings, joint sealant types and issues, and expansion joint sealant systems.
Figure 11. Reinorcing bars o various sizes, rom no. 18 to no. 3.
In the event that a precast concrete component is damaged during transportation or erection, in-service repairs are reviewed. Other in-service conditions are also examined, and suggested maintenance and strengthening means are provided. The chapter concludes with section 9.9, Relevant Standards and Publications, which is a comprehensive listing o reerence standards and publications relevant to materials. These standards may also appear in project specifcations prepared by the engineer o record or architect o record.
Chapter 10—Design for Fire Resistance of Precast and Prestressed Concrete
Figure 12. Example o good air-void system.
Section 9.4, Connection Materials, reviews the common steel sections, bearing pads, and bolts used in connections. This is ollowed by a discussion on the galvanic series and its importance in examining service lie and protection o connections. Protection means are discussed, including painted systems, galvanized steel, and stainless steel, and the proper means o speciying them. Section 9.6, Reinorcement, describes various systems or precast and prestressed concrete components and the various deterioration mechanisms that can occur. Dierent means o embedded steel protection are presented to mitigate common deterioration problems. Other means o pro-
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This was section 9.3 in the sixth edition and is now a standalone chapter to emphasize the many benefts o precast concrete in fre protection. Section 10.6.2, Continuous Components (section 9.3.7.2, Continuous Members, in the sixth editi on), has been shortened by eliminating other loading conditions beyond the two-span case discussed. Reer to PCI MNL-124-8923 or additional load case discussion. Example 9.3.7.1, Fire Endurance or Hollow-Core Slab with Topping, rom the sixth edition has been eliminated because most applications or residential use do not use topping and still satisy fre-endurance requirements. Example 10.8.1, Fire Endurance by Code Tables, or a double-tee with topping, has been updated to reect IBC 2006.
A new section 10.8, Requirements or Parking Structures, has been added to assist the user in applying the requirements and tables in IBC 2006 to the design o precast and prestressed concrete components typically used in parking structures. Several paragraphs that outline recent research at Lehigh University are included in this section. This research was perormed to evaluate realistic vehicle-fre loads (time-temperature or time-heat ux relationships) or precast concrete parking structures. This work investigated the inuence o the structural geometry and fre characteristics on the resulting fre load.
Chapter 11—Thermal and Acoustical Properties of Precast Concrete The topics o chapter 11 comprise sections 9.1 and 9.2 rom the sixth edition. The chapter provides updated inormation on both topics, as well as adding design guidelines or calculating the thermal resistance o sandwich panels using metal ties between concrete wythes.
Chapter 12—Vibration Design of Precast/Prestressed Concrete Floor Systems This was section 9.7 in the sixth edition and is now a standalone chapter to demonstrate the importance o vibration control in certain types o acilities. There are no signifcant changes; however, a minor change is the addition o three double-tee sections to Fig. 12.4.1 (Fig. 14). They are 12DT28+2, 12DT30, and 15DT34.
Chapter 13—Tolerances for Precast and Prestressed Concrete Chapter 13 in the seventh edition was chapter 8 in the sixth edition. It was moved to accommodate other major changes in the layout o the PCI Design Handbook . The only other changes are editorial and correction o some minor errors.
Chapter 14—Specifications and Standard Practices This chapter was chapter 10 in the sixth edition. The most signifcant change rom the previous edition was the reorganization o the sections. PCI St andard Design Practice (section 14.1) has been placed frst because it is believed to be the most important inormation or the
Figure 14. Natural requency o selected foor units.
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designer in the chapter. It has been updated to reect ACI 318-05 and has had extensive review by the PC I Building Code Committee and TAC. Sections 14.2 and 14.3 are brie descripti ons o the guide specifcations or structural and architectural precast concrete, respectively. They have both been updated to the latest ACI 301 and AIA Masterspec.24,25 The ull guide specifcations are on the CD in the ront jacket pocket o the PCI Design Handbook and are in a usable word-processing ormat.
Appendix—Impact of ACI 318-08 on this Handbook The appendix is totally new and is the result o PCI’s TAC directing that the impact o ACI 318-08 27 be included in the seventh edition. It is based entirely on our papers written by S. K. Ghosh and published as a supplement to separate issues o the PCI Journal.28–31 The PCI Industry Handbook Committee reviewed those papers and included in the appendix those portions that have an impact on sections o the handbook.
Conclusion Section 14.4, Standard Operations Practice Recommendations or Precast Concrete, has been updated to reect current practices in the industry. Section 14.5, Recommendations on Responsibility or Design and Construction o Precast Concrete Structures, remains essentially the same as in the sixth edition.
Chapter 15—General Design Information This chapter was chapter 11 in the sixth edition. The ollowing is a listing o the most signifcant changes in this chapter: •
•
•
•
•
All Design Aids have been reorganized to better reect the topic. All Design Aids have been updated to reerence the current model codes and standards. Numerical values have been modifed where required. For example, the uniorm oor loading in passenger-car parking structures was revised rom 50 lb/t 2 (244 kg/m2) to 40 lb/t2 (195 kg/m2). The sixth-edition Design Aid 11.2.1 has been omitted rom the seventh edition because it is easy to calculate the values that are a unction o the concrete strength. The sixth-edition Design Aid 11.2.2 has been updated in the seventh edition as Design Aid 15.2.1 to include the recommended curves using two recognized equations or the modulus o elasticity o concrete.
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Chapter 2, Notations, was intended to include defnitions used throughout the handbook, as well as other te rms typically used in the industry that might not be specifcally used in the handbook. Terms such as down-in-orm, chuck , stripping, dunnage , and the like are used in everyday conversation in plants and may be helpul or the inexperienced designer or student using the handbook. A review o chapter 2 also resulted in the observation that the notation used in the handbook could be improved with a complete overhaul. Many o the same notations have dierent meanings, which can cause conusion. Examples include the notation R, which is the response modifcation actor or seismic design in chapter 4 and the thermal resistance o a precast concrete component in chapter 11. There are numerous less-critical topics and suggested changes brought orward or consideration, but the decision to incorporate them was postponed because o t iming and publishing constraints. Similar thoughts occurred during the blue-ribbon review. The committee has gathered these items or uture consideration and has provided them to the next PCI Industry Handbook Committee, to be chaired by Tim Salmons, P.E., S.E. The list o items or the eighth edition o the PCI Industry Handbook Committee to address also includes: •
The new seventh-edition Design Aid 15.4.2 has been added and includes typical bent reinorcing bar confgurations and designations. The source or this inormation is ACI’s publication Details and Detailing o Concrete Reinorcement.26
•
Most o the goals established by the PCI Industry Handbook Committee or the seventh edition have been accomplished. However, several were not and will remain goals or the eighth edition, as noted in the ollowing paragraphs.
The new seventh-edition Design Aid 15.5.4 has been added and illustrates common styles o welded-wire reinorcement (WWR) shear reinorcement used in the ends o double-tee stems.
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•
•
ACI 318 intends a major revision in 2013, with only an interim revision in 2011. PCI’s TAC will direct the PCI Industry Handbook Committee as to which versions o ACI 318, IBC, and ASCE will be used or the eighth edition. Consider making the publication a t wo-volume set, with one including material that does not necessarily change with the code cycles. Use 3 in. (75 mm) topping or double-tee load tables instead o 2 in. (50 mm).
•
•
•
Reintroduce material related to erection bracing and include examples.
3.
Quality Control or Plants and Production o Structural Precast Concrete Products. MNL-116-99. 4th
Create a uniorm ormat or all examples and all fgures. Consider providing a fnal drat o the eighth e dition to the entire engineering community or public comment. While the seventh edition has had a very intense review process, it cannot be considered a consensus document. Responding to public comments would allow the document to achieve this status.
ed. Chicago, IL: PCI. 4.
3rd ed. Chicago, IL: PCI.
Update the handbook to reect ongoing research.
As stated in the oreword, the PCI Design Handbook is a living document. Comments related to any aspect o the handbook are encouraged and much appreciated. This handbook has had a very intensive review at several levels. It must be understood, however, that all errors may not have been observed and corrected during these reviews. PCI thereore intends to publish errata based on input o the users o the handbook over the next several months. The errata will also be posted on PCI’s website at www.pci.org. Address all comments to PCI’s Managing Director o Technical Activities at PCI, Jason Krohn, 200 West Adams Street, Suite 2100, Chicago, IL 60606.
a.
b.
c.
Figure 4.8.4 o the seventh edition is not correct in that the horizontal line just above the lower shear wall on the right side o the plan should line up with the end o that shear wall. Figure 3 in this article is correct. Example 5.2.3.2 does not correctly reect the text o the seventh edition in that it does not properly account or load in the partially developed strands. Use o E70 electrodes has been a common practice in the industry or years. The statement that this is no longer allowed by AWS D1.4 is incorrect. Reer to the sixth-edition PCI Design Handbook , which is correct.
References 1.
2.
PCI Industry Handbook Committee. 2010. PCI Design Handbook: Precast and Prestressed Concrete. MNL120-10. 7th ed. Chicago, IL: PCI. American Concrete Institute (ACI) Committee 318. 2005. Building Code Requirements or Structural Con-
PCI Glass Fiber Reinorced Concrete Panels Committee. 2009. Manual or Quality Control or Plants and Production o Glass-Fiber Reinorced Concrete Products . MNL-130-09. Chicago, IL: PCI.
6.
American Society o Civil Engineers (ASCE). 2005. Minimum Design Loads or Buildings and Other Structures. Structural Engineering Institute (SEI)/
ASCE 7-05 and Supplement No. 2. Reston, VA: ASCE. 7.
International Code Council. 2006. International Building Code 2006 . Falls Church, VA: ICC.
8.
PCI Bridge Design Manual Steering Committee. 1997. Precast Prestressed Concrete Bridge Design Manual . MNL-133-97. 1st ed. Chicago, IL: PCI.
9.
PCI. 1981. Reections on the Beginnings o Prestressed Concrete in America. Chicago, IL: PCI.
Postpublication Notes Ater publication o the handbook, several errata that aect this article were observed as ollows. These and other errata will be published in a uture issue o the PCI Journal.
PCI Architectural Precast Concrete Services Committee and Plant Certifcation Committee. 1996. Manual or Quality Control or Plants and Production o Architectural Precast Concrete Products. MNL-117-96.
5. •
PCI Plant Certifcation Committee. 1999. Manual or
10. Schutt, Craig, ed. 2004. PCI 50 Years: Visions Taking Shape. Chicago, IL: Cherbo Publishing Group Inc. 11. Klein, G. J., and R. J. Lindenberg. 2009. Volume Change Movement and Forces in Precast Concrete Buildings. Research report, PCI, Chicago, IL. 12. Cleland, Ned and S. K. Ghosh. 2007. Seismic Design o Precast/Prestressed Concrete Structures. MNL140-07. Chicago, IL: PCI. 13. Mattock, A. H., W. K. Li, and T. C. Wang. 1976. Shear Transer in Lightweight Reinorced Concrete. PCI Journal , V. 32, No. 1 (January–February): pp. 20–39. 14. Klein, G. J. 1986. Design o Spandrel Beams. PCISFRAD project no. 5. PCI Journal, V. 31, No. 5 (September–October): pp.76–124. 15. PCI Committee on Prestressed Concrete Columns. 1988. Recommended Practice or the Design o Prestressed Concrete Columns and Walls. PCI Journal, V. 33, No. 4 (July–August): pp. 56–75.
crete (ACI 318-05) and Commentary (ACI 318R-05).
Farmington Hills, MI: ACI.
16. Aswad, Alex, and George Burnley. 1991. Point Load
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Tests o Double-Tee Flanges. PCI Journal, V. 36, No. 4 (July–August): pp. 66–73. 17. Mack, P., G. Force, C. Magnesio, and K. Bryan. 2003. The Practice o Warping Double-Tees. PCI Journal, V. 48, No. 1 (January–February): pp. 32–48. 18. Concrete Technology Associates (CTA). 2000. Ductile Pullout Connections. CTA Technical Bulletins, Vol. II. Chicago, IL: PCI. 19. American Welding Society (AWS). 2002. Structural Welding Code—Reinorcing Steel. AWS D1.4-02. Miami, FL: AWS. 20. PCI Architectural Precast Concrete Committee. 2007. Architectural Precast Concrete. MNL-122-07. 3rd ed. Chicago, IL: PCI. 21. Logan, D. 2010. Erecting Long, Vertical Precast Concrete Members with One Crane and Two Operating Lines. PCI Journal, V. 55, No. 1 (Winter): pp. 118–136. 22. American Society o Civil Engineers (ASCE)/Structural Engineering Institute (SEI). 2002. Design Loads on Structures During Construction. SEI/ASCE 37-02. Reston, VA: ASCE. 23. PCI Fire Committee. 1989. Design or Fire Resistance o Precast Prestressed Concrete. MNL-124-89. 2nd ed. Chicago, IL: PCI. 24. American Institute o Architects. 2006. Masterspec 2004. Salt Lake City, UT: ARCOM. 25. ACI Committee 301. 2010. Specifcations or Structural Concrete. Farmington Hills, MI: ACI. 26. ACI. 1999. Details and Detailing o Concrete Rein orcement. ACI 315-99. Farmington Hills, MI: ACI. 27. ACI Committee 318. 2008. Building Code Requirements or Structural Concrete (ACI 318-08) and Commentary (ACI 318R-08) . Farmington Hills, MI: ACI.
28. Ghosh, S. K. 2008. Signifcant Changes to ACI 318-08 Relative to Precast/Prestressed Concrete: Part 1. PCI Journal. Suppl. no. 53-2. 29. Ghosh, S. K. 2008. Signifcant Changes to ACI 318-08 Relative to Precast/Prestressed Concrete: Part 2. PCI Journal. Suppl. no. 53-3. 30. Ghosh, S. K. 2008. Signifcant Changes to ACI 318-08 Relative to Precast/Prestressed Concrete: Part 3. PCI Journal. Suppl. no. 53-5.
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31. Ghosh, S. K. 2009. Signifcant Changes to ACI 318-08 Relative to Precast/Prestressed Concrete: Part 4. PCI Journal . Suppl. no. 54-3.
