Modern CONSTRUCTION
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February 2018
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February 2018 42
in every issue departments 6 9 12 60 61 66
EDITOR’S NOTE STEEL INTERCHANGE STEEL QUIZ NEW PRODUCTS NEWS STRUCTURALLY SOUND
resources 65 MARKETPLACE & EMPLOYMENT
columns manualwise Designing Beam Copes
16
BY BO DOWSWELL, PE, PHD The lates t edit ion of the A ISC Manua l includes updated design methods for beam copes.
business The Big Change
22
BY ANDY SLIPHER What ha s real ly chan ged wit h market ing in the last 100 years? Just one thing. Really.
features conference preview Core Solution
24
BY BRIAN MORGEN, SE, PE, PHD, RON KLEMENCIC, SE, PE, HON. AIA, AND AMIT VARMA, P HD A new compos ite asse mbly is pos itioned to set the pace for future high-rise building s and elevate steel to dominance in core construction.
30
Vision of the Future BY MICHELLE BLACK, PE, CHRIS ADAMS, PE, AND SHANE MCCORMICK, SE, PE Various engineerin g and science disciplines come together under one roof in a modern, steel-framed research facility funded by one of Colorado’s most prominent names.
36
High Art BY STEVE MARUSICH, SE
48
A new art b uilding bri ngs its ow n sense of style and flair to the Stanford campus.
42
A seemi ngly sma ll st ruct ural r etrof it at the bottom of a prominent Manhattan high-rise brings big gains to occupants and visitors.
BY JOSEPH SAVALLI, PE, BORYS HAYDA, PE, AND MATTHIEU PEULER, PE Downtown Brooklyn gets a big boost from a multi-phase development that successfully interweaves various framing systems.
Playing to the Base BY JOHN HINCHCLIFFE, PE, JOE MUGFORD, PE, AND RAMON GILSANZ, SE, PE
Building Up Brooklyn
52
Feeding Growth BY TARA REEB A steel-f ramed dini ng faci lity a nd surrounding buildings come together quickly on a fast-growing college campus.
56
Rising to the Challenge BY JOE DARDIS, PE As t he high-r ise mark et conti nues to grow, so do the opportunities for structural steel in skylines across the country.
ON THE COVER:
Stanford’s new McMurtry Building provides lessons on art, art history, architecture and even structural engineering, p. 36. (Photo by Iwan Baan, Courtesy Diller Scofidio + Renfro) MODERN STEEL CONSTRUCTION (Volume 58, Number 2) ISSN (print) 0026-8445: ISSN (online) 1945-0737. Published monthly by the American Institute of Steel Construction (AISC), 130 E Randolph Street, Suite 2000, Chicago, IL 60601. Subscriptions: Within the U.S.—single issues $6.00; 1 year, $44. Outside the U.S. (Canada and Mexico)—single issues $9.00; 1 year $88. Periodicals postage paid at Chicago, IL and at additional mailing offices. Postmaster: Please send address changes to MODERN STEEL CONSTRUCTION, 130 E Randolph Street, Suite 2000, Chicago, IL 60601. DISCLAIMER:AISC does not approve, disapprove, or guarantee the validity or accuracy of any data, claim, or opinion appearing under a byline or obtained or
quoted from an acknowledged source. Opinions are those of the writers and AISC is not responsible for any statement made or opinions expressed in MODERN STEEL CONSTRUCTION. All rights reserved. Materials may not be reproduced without written permission, except for noncommercial educational purposes where fewer than 25 photocopies are being reproduced. The AISC and Modern Steel logos are registered trademarks of AISC.
4 FEBRUARY 2018
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WHEN MY DAUGHTER LEFT TOWN RECENTLY TO STUDY ABROAD IN LONDON, ONE OF THE ATTRACTIONS SHE SAID SHE WANTED TO SEE WAS THE CHANGING OF THE GUARD.
That phrase seems particularly people annually. Today, we’ve created appropriate to me as I look at AISC today. a robust online continuing education When I started here nearly 30 years ago, presence with an annual audience I was part of a vanguard of fresh employees of around 20,000 people. And those who helped to reshape the Institute. Cindi 5,000 people we used to see in person Duncan joined AISC a couple of years at seminars? We now see them at a before me, took a few years off and is single unified event (NASCC: The Steel now our director of engineering. The year Conference) and at a select number of before I started, Bill McEleney (who would in-person seminars. eventually become managing director of But even more importantly, Nancy was the National Steel Bridge Alliance) signed the creator and the driving force behind on. We had a new legal counsel, David AISC’s Night School program. These webRatterman. And shortly after I started, a based programs offer a series of seminars whole series of new hires helped revitalize on a single topic (our fall program, for AISC, including Charlie Carter (who is now example, focused on the fundamentals of president of AISC) and Tom Schlafly (our connection design). Each topic typically director of research). features seven lectures and provides a The changes today, though, are much more in-depth continuing education perhaps even more dramatic. In addition experience than a typical seminar. to Charlie becoming president, we have But Nancy’s contributions weren’t just a new vice president of certification (Mark limited to continuing education. She was Trimble, who brings more than four decades also instrumental is working with students of experience in the industry), a new vice and faculty to improve the state of steel president of engineering and research education. She developed and provided (Larry Kruth, who has more than 40 years of meaningful assistance to professors through design, fabrication and erection experience), new teaching resources, grew the ACSA/ a new vice president of market development AISC Steel Design Student Competition (the homegrown Tabitha Stine, who is trying and built a model program for connecting to fill the huge shoes of the legendary John professors and students with working Cross, who is now our vice president of professionals at The Steel Conference. special projects) and a new vice president of And she was successful at developing finance (Anne-Marie Eischen). In all, nearly a great staff, so the changing the guard a third of AISC’s staff is either new to the includes promoting Christina Harber to Institute or new to their roles. director of education. And the changes continue. Just last I hope all of you have the opportunity month, Nancy Gavlin, AISC’s director of education, retired. Unless you were an educator, you might not know Nancy, but her impact on AISC was huge. Under her tenure, AISC’s educational strategy transitioned from in-person seminars to web-based learning. Before Nancy, we typically held 40 to 60 lectures in cities around the country, reaching nearly 5,000 6 FEBRUARY 2018
to meet these new leaders. Please stop by AISC’s booth at NASCC: The Steel Conference in Baltimore in April and say hello to both the new and the familiar faces.
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If you’ve ever asked yourself “Why?” about something related to structural steel design or construction, Modern Steel’s monthly Steel Interchange is for you! Send your questions or comments to
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steel interchange
Note: Unless specifically noted, all AISC publications mentioned in the questions and/or answers are independent of the edition and can be found at www.aisc.org/specifications .
Yes. If you are seeing structural steel buildings using R = 3¼, then I assume that the building is designed as a steel ordinary concentrically braced frame system (OCBF) type B.3 in ASCE 7-10, Table 12.2.-1, and OCBFs need to satisfy the applicable
Thin and Welding I havePlates specified ¼-in. plates to be welded to structural
Provisions sections of Seismic . Chapter F, Section F1system, outlines some of the requirements specific to this particular and F1.6 specifically refers to connections. Additionally, there are general requirements in Chapters A through D and quality control and quality assurance requirements in Chapter J, which also need to be considered. It should be noted that Section A4.1 lists information that must be included in the structural design documents and specifications. Much of this information is intended to clarify the project requirements as they related to the Seismic Provisions. If this information has not been provided, then it should be requested. One of the listed items is the designation of the seismic force resisting system (SFRS). If my assumption above is correct, the SFRS should be designated as OCBF. I will also state that this seems like an unusual choice. Generally, a system not specifically detailed for seismic resistance (R = 3) would be a more economical option for a structure in Seismic Design Category C. Susan Burmeister, PE
members for aesthetic considerations. Some of the fabricators bidding the project have indicated that there may be issues associated with welding plate that is this thin. They have mentioned weld show-through and distortions as potential concerns. Are these valid considerations? What can be done to address them?
In general, when the company charged with performing the work indicates that they will have difficulty satisfying your expectations, their concerns should be taken seriously and viewed as valid. This does not mean that the issues are insurmountable, but it does indicate that the conditions deserve some greater consideration. A ¼-in. plate is thinner than what many structural steel fabricators will be used to working with. Their equipment will commonly be set up to deposit a 5∕16-in. fillet weld to the thicker material, probably a minimum of 3∕8 in. thick. Both weld show-through and distortion are related to weld size and Weight Savings of Intermediate Moment Frames material thickness. It may be possible to use different equipment and processes We are bidding fabrication for a project in Seismic Design Category B. The SFRS is designated as using intermedito reduce the amount of distortion, though this will likely increase the cost of the fabrication. Theoretically, a 1∕8-in. fil- ate moment frames (IMF). This is an unusual system in let weld could be used, which would produce significantly less our area, and we have suggested that it may be more ecoheat input than is typically seen in structural steel fabrication. nomical to design it so that it isn’t specifically detailed for You may also want to consider whether the plate can be stitch seismic resistance (R = 3). It has been asserted that our welded. Stitch welding will reduce the heat induced in the suggestion would in fact be less economical due to the increased weight of the members. Is this correct? plate, thereby minimizing distortion. Another alternative may be to use thicker material, if posA: The choice of an IMF with an R = 4.5, as opposed to a sible, while still satisfying the aesthetic requirements. Using thicker system not specifically detailed for seismic resistance with material might allow the fabricator to use more typical and efficient an R = 3, will result in a smaller base shear due to the seisequipment and processes, resulting in economical fabrication. Larry S. Muir, PE mic loads and may also result in lighter members. However, requirements to use moderately ductile beam and column memThe next three items all relate to the choice of seismic system and bers may reduce or eliminate the benefit relative to weight. Other requirements related to fabrication, such as requirehow this choice relates to complexity and cost. We receive a fair number of questions like the ones below and felt that presenting these three as a group might be instructive.
Seismic Response Modification Coefficient, Given as 3¼
R,
As a fabricator, we are starting to see buildings in Seismic Design Category C with the seismic response modification coefficient, R, given as 3¼ in the General Notes. Will these structures have to satisfy the Seismic Provisions for Structural Steel Buildings (ANSI/AISC 341)?
ments may to provide or prequalified tions, result inqualified an increased overall costmoment for the connecproject, even if there is a reduction in weight of the members. AISC generally recommends choosing systems not specifically detailed for seismic resistanceR( = 3) whenever permitted, if the economy of the structure is the primary consideration. AISC has long taken the position that least weight does not correlate to least cost. This applies to seismic design as much as it does to sizing columns to avoid the need for reinforcing at moment connections. Thomas J. Schlafly Modern
STEEL CONSTRUCTION
9
steel interchange Conveyors in a High-Seismic Area We are designing steel conveyors in a high-seismic area. For steel ordinary moment frames (OMFs), Chapter 15 of ASCE 7-10 permits the use of R = 1 without having to satisfy the Seismic Provisions or R = 2.5 when the Seismic Provisions are satisfied. We have reviewed Section E1 of the Seismic Provisions and believe that we can take advantage of the higher seismic response factor of 2.5 by simply providing a direct-welded moment connection with CJP (complete joint penetration) groove welds at the flanges. This detail would seem to satisfy the requirement to design the beam-to-column moment connection for 1.1RyFyZx. Is there anything we are missing? The Specification for Structural Steel Buildings (ANSI/AISC 360) and Seismic Provisions both address the building design, and applying their provisions to nonbuilding structures requires engineering judgment relative to how similar the structure’s behavior will be to that of a building, and whether any adjustment should be made to account for the differences. From your description, I believe you are looking at an OMF system. AISC does not provide requirements related to the range of available systems; these requirements are provided in ASCE-7. You may want to contact ASCE if you have questions related to their requirements. However, it does seem odd to me that a conveyor would be designed to meetin Chapter 15. Manufacturing or process conveyors are included Chapter 13, and treating the conveyors as nonstructural components may be more appropriate. There may be reasons to treat this particular conveyor as a nonbuilding structure similar to a building, but this is not the norm. Relative to evaluating the R = 2.5 and the R = 1 options, you have not identified all of the potential impacts that using an OMF could have on your project. One mistake engineers sometimes make is that they think the system chapters in the Seismic Provisions are self-contained. Section E1 does not contain all of the requirements that will apply to your project. Requirements of Chapters A through D and Chapters I through J will also apply, and even some of the Chapter K requirements could have an impact. For example, your contract documents will have to satisfy A4. If you do not address all of these requirements adequately, you may have to address RFIs, which could lead to you changing the contract requirements after award. This could lead to revisions to the contract with potential cost and schedule impacts. Section D2.2 addresses requirements for bolted joints. All bolts will have to be pretensioned, which might be done for a conveyor anyway to prevent loosening, but all faying surfaces in the SFRS (with a few exceptions) will also have to be qualified for slip resistance. If the members are galvanized, the
10 FEBRUARY 2018
faying surfaces will have to be hand-wire brushed. If the members are painted, they will have to be masked or a qualified paint must be used. In addition to AWS D1.1, AWS D1.8 must also be satisfied, and quality control and assurance tasks are expanded. Note that this is not intended to be a complete list but is rather intended to illustrate some of the provisions that might impact the work. There are also practices that could make the structure more economical that you might overlook if you are not wellacquainted with the Seismic Provisions. For example, you state that the connections must develop the expected strength of the beam, 1.1 RyFyZx. This is not exactly correct. There are exceptions to this default requirement that might apply to your structure and might lead to a more economic result. Generally, AISC encourages engineers to use steel systems not specifically detailed for seismic resistance whenever possible. This guidance applies to buildings, so the base shear is derived from R = 3 instead of R = 1. AISC has no position on the relative benefit of moving from R = 1 to OMF with R = 2.5. In my opinion, unless you are already familiar with the Seismic Provisions and have already worked on projects required to meet the Seismic Provisions, you might be better off going with the R = 1 option. Larry S. Muir, PE
The complete collection of Steel Interchange questions and answers is available online. Find questions and answers related to just about any topic by using our full-text search capability. Visit Steel Interchange online at www.modernsteel.com .
Larry Muir is director of technical assistance and Tom Schlafly is director of research, both with AISC. Susan Burmeister is a consultant to AISC.
Steel Interchange is a forum to exchange useful and practical professional ideas and information on all phases of steel building and bridge construction. Opinions and suggestions are welcome on any subject covered in this magazine. The opinions expressed in Steel Interchange do not necessarily represent an official position of the American Institute of Steel Construction and have not been reviewed. It is recognized that the design of structures is within the scope and expertise of a competent licensed structural engineer, architect or other licensed professional for the application of principles to a particular structure. If you have a question or problem that your fellow readers might help you solve, please forward it to us. At the same time, feel free to respond to any of the questions that you have read here. Contact Steel Interchange via AISC’s Steel Solutions Center: 866.ASK.AISC •
[email protected]
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steel quiz
If you thought this month’s Quiz would allow you to ll in the blanks and/ or choose from a list of options or between true and false for each question, we’re happy to disappoint you! Instead, we’ll put your equations skills to the test using a sample HSS design.
Use the information and framework provided below to approximate the design flexural strength of a composite HSS10×10×3⁄8 member. Neglect the corner radius Fy = 50ofksithe andHSS f’c =shape. 5 ksi. Determine yt Write expressions for the tension and compression components of the moment couple as a function of depth, Y: Example: Cc = 0.85f’c [9.3 × (Y – 0.35)] = 39.53 Y – 13.83 Cs = Ts =
With the sum of the forces equal to zero, solve for Y: Cs + Cc = Ts Cs + 39.53Y – 13.83 = Ts Solve for Y, Y = ______ Determine yc for concrete area: yc =
Area
1
A
Determine yb y
3.25
Ay
Area
2
2
3
3
yt =
A
1
(∑Ay) = (∑A)
yb =
y
Ay
3.25
(∑Ay) = (∑A)
Finally, calculate the design flexural strength. φMn = 0.9 × [(Cc × yc) + (Cs × yt) + (Ts × yb)] φMn = TURN TO PAGE 14 FOR THE ANSWERS
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steel quiz
ANSWERS
The V15.0 Design Examples, a free download at www.aisc.org/designexamples, provides composite HSS tables with a design flexural strength of 198 kip/ft (see page IV-71/page 1057 of the PDF).
Write expressions for the tension and compression components of the moment couple as a function of depth, Y: Cc = 0.85f’c [9.3 × (Y – 0.35)] = 39.53Y – 13.83 Cs = 0.35(9.3 + 2Y) Fy = 162.75 + 35 Y Ts = 0.35(9.3 + 2(10 – Y)) Fy = 512.75 – 35 Y With the sum of the forces equal to zero, solve for Y: Cs + Cc = Ts 162.75 + 35Y + 39.53Y – 13.83 = 512.75 – 35Y Solve for Y, Y = 3.32 in. Determine yc for concrete area: (Y – t) (3.32 – 0.35) yc = = = 1.49 2 2
Determine yb
Determine yt Area A
y
Area A
Ay
y
Ay
1
3.25
3.14
10.21
1
3.25
6.51
21.16
2
1.16
1.66
1.93
2
2.33
3.34
7.78
3
1.16
1.66
1.93
3
2.33
3.34
7.78
(∑Ay) 14.07 (∑Ay) 36.72 = 2.53 yb = = 4.64 = = (∑A) (∑A) 7.91 5.57 Calculate the design flexural strength. φMn = 0.9 × [(Cc × yc) + (Cs × yt) + (Ts × yb)] φMn = 0.9 × [(117.41 × 1.49) + (278.95 × 2.53) + (396.55 × 4.64)] = 2449 kip-in = 204 kip-ft yt =
Anyone is welcome to submit questions and answers for the Steel Quiz. If you are interested in submitting one question or an entire quiz, contact AISC’s Steel Solutions Center at 866.ASK.AISC or at
[email protected] .
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manualwise DESIGNING BEAM COPES
The latest edition of the AISC Manual includes updated design methods for beam copes.
BY BO DOWSWELL, PE, PHD
THE DESIGN METHODSfor
single- and double-coped beams have been revised for the 15th Edition Steel Construc-
tion Manual.
Here, we’ll discuss the new design provisions and provide so me b ackgroun d information on the local strength of coped beams, as well as new design recommendations for axially loaded beams based on the latest research. Beam to Beam
Let’s start with beam-to-beam connections. In such connections, the top ange of the supported beam is usually coped to clear the supporting beam ange (see Figure 1). In some cases, the bottom ange must be coped to clear the supporting beam ange or to allow the beam to be dropped between two angles, as shown for the knife connection in Figure 2. For double-coped beams, where both the top and bottom ange are coped, a signi cant portion of the web is often removed. Figure 3 (opposite page) shows a skewed beam-to-beam connection with a long double cope at the supported beam. For design purposes, the coped region can be modeled as a short beam with a length equal to the cope length. In addition to the constant shear force, R, the cope is subjected to a linearl y-varying moment. The maximum moment is at the face of the cope, causing compressive flexural stresses at the reentrant corner, as shown in Figure 4. Due to the combined effect of the flexural and shear stre sses, the cope
Bo Dowswell(bo@arcstructural. com)
is a principal with ARC International, LLC, in Birmingham, Ala., and also a consultant to AISC’s Steel Solutions Center.
16 FEBRUARY 2018
➤Figure 1. Beam coped at the top flange. ➤
Figure 2. Beam coped at the bottom flange.
manualwise ➤
Figure 3. Skewed beam-to-beam connection.
strength can be limited by either yielding or buckling. Design recommendations in previous editions of the AISC Manual imposed limits on the cope geometry and were based on an allowable stress philosophy, limiting the exural strength to the rst-yield moment. To eliminate the limits of applicability and provide equations that take advantage of any available post-yield strength, the design guidance in the 15th Edition Manual (www.aisc.org/manual) has been revised from these previous editions. Single-Coped Beams The web of a single-coped beam can buckle in a local mode, similar to the buckling of a tee stem in exural compression. Therefore, the exural strength equations in Part 9 of the Manual are similar to the three-part local buckling curves in Chapter F of the Speci cation for Structural Steel Buildings (ANSI/AISC 360, available at
www.aisc.org/speci cations). Figure 5 (page 18) shows the single-cope curve with the available experimental results. As with the Speci cation, the equations produce a linear transition between the plastic strength and the elastic buckling curve. The shear strength is calculated according to AISC Speci cation Section J4.2. Flexural local buckling is likely to dominate the buckling mode for beams with long copes. Shear buckling, where the buckled shape is characterized by a single wave oriented at an angle of approximately 45° from vertical (Figure 6, page 18), occurs in beams with short cope lengths. Because most instabilities in single-coped beam webs are caused by a combination of shear buckling and exural local buckling,
Manual the infactor, Part 9 use afor bucklingequations adjustment f, to account the effect of shear. Combined block shear and cope buckling (block shear buckling) can occur at short copes with shallow end con-
➤
Face of Cope Setback
Out-of-Plane Restraint
➤a. single-cope ➤
b. double-cope
Face of Cope Setback
Out-of-Plane Restraint
Figure 4. Design model. Modern
STEEL CONSTRUCTION
17
manualwise Figure 5. Buckling curve for singlecoped beams.
Figure 6. Shear buckling of a singlecoped beam.
Figure 7. Block shear buckling.
Buckle
Rupture
nections, as shown in Figure 7. The failure is characterized by a combination of extensive yielding along the L-shape block shear failure pattern, with potential rupture at the tension plane, and localized buckling at the face of the cope.
18 FEBRUARY 2018
Based on the experimental results, it is believed that this failure mode can be eliminated by providing a minimum connection element depth of h 0/2, where h 0 is the depth of the coped section.
➤
Figure 9. Shear buckling variable definitions.
➤Figure 8. Buckled shape of a
double-coped beam.
For further information on the background of the revised design guidelines for single-coped beams in the 15th Edition Manual, keep an eye out for the pending Engineering Journal article “Strength of Single-Coped Beams” (www.aisc.org/ej). Double-Coped Beams Figure 8 shows the buckled shape of a double-coped beam web, which is characterized by lateral translation and twisting. Because the behavior is similar to that of a rectangular beam, the design procedure was developed based on a lateral-torsional buckling model with an adjustment factor determined by curve tting data from the nite element models. The exural strength is determined in accordance with Speci cation Section F11, with Cb calculated using the equations in Manual Part 9. In most cases, the top and bottom cope lengths are equal and Manual Equation 9-15 is applicable. An advantage of the new design procedures in the 15th Edition Manual is the ability to calculate the strength where different cope lengths are required at the top and bottom anges (Figure 9). When the bottom cope is equal to or longer than the top cope length, the bottom cope size has a negligible effect on the cope strength and Manual Equation 9-15 is valid. When the top cope is longer than the bottom cope, Cb is calculated with Manual Equation 9-16.
In most cases, the shear strength of double-coped beams can be calculated according to the shear yielding limit state in Speci cation Section J4.2. However, the experimental results showed that beams with slender webs and short copes can fail by shear buckling, where the buckle extends into the beam web at an angle of approximately 45° from vertical, well beyond the
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Modern
STEEL CONSTRUCTION
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manualwise
➤Figure 10. Shear buckling of a
double-coped beam.
➤
Figure 11. Shear buckling variable definitions.
Face of Cope Setback Out-ofPlane Restraint
Inflection Point ➤Figure 12. Inflection point location. ➤
Figure 13. Axially loaded beam.
face of the cope (Figure 10). In this case, the shear strength can be calculated according to Speci cation Section G3, with kv = 3.2, φ = 1.00 and Aw = hotw, where tw is the web thickness. As shown in Figure 11, h = d – dct, where d is the beam depth and dct is the depth of the top cope. For further information on the background of the revised design guidelines for single-coped beams in the 15th Edition Manual, see “Local Stability of DoubleCoped Beams” in the First Quarter 2014 Engineering Journal (www.aisc.org/ej).
Axial Loads
For both single- and double-coped beams, the available exural strength, Mc, must be equal to or greater than the required exural strength, Mr. The required exural strength is the maximum moment within the cope, Mr = Rre, where Rr is the required beam end reaction. In Part 9 of the Manual, e is de ned as the “distance from the face of the supporting member to the face of the cope, unless a lower value can be justi ed.” For idealized connections, e is the distance from the face of the sup-
As mention previously, copes subjected to shear are modeled as a short beam with a length equal to the cope length. This model is also applicable to copes subjected to axial loads (Figure 13). The axial tension strength of both single- and double-coped beams is calculated according to Speci cation Section J4.1. Similar to the exural strength calculation, the axial compression strength is based on the expected buckling mode. Because exural buckling is the controlling limit state for double-coped beams, Speci cation Section J4.4 is applicable. For single-coped beams, web local buckling is the controlling limit state and the strength can be evaluated according to Speci cation Section E7. However, the cope length is usually less than the local buckling half-wavelength, causing some conservatism when applying the Speci cation equations to common cope geometries. A more accurate design method, based on a modi ed version of the Speci cation equations, will be discussed in the accompanying NASCC presentation. The axial and exural loads must be
porting element to the face of the cope as shown in Figure 4. However, the rotational rigidity of real connections tends to move the in ection point toward the beam midspan as shown in Figure 12, reducing the moment at the face of the cope. Due to dif culties in accurately predicting the in ection point location, standard design practice is to de ne e as shown in Figure 4, neglecting the in uence of any connection rotational restraint. In some cases, it may seem appropriate to de ne e as the distance from the in ection point to the face of the cope. However, the design equations include the effects of shear stress and moment gradient over the cope length. Therefore, these effects must be considered before using the in ection
combined, and in some cases, an additional calculation combining the axial and shear loads may also be required. For both single- and double-coped beams, axial and exural loads can be combined using linear interaction according to Speci cation Section H2. For coped beams subjected to axial tension, no axial-shear interaction is required. For single-coped beams subjected to axial compression, linear interaction of the axial and shear loads is required. For double-coped beams subjected to axial compression, linear interaction of the axial and shear loads is required only when Cv2 < 1.0 (Speci cation Section G3). Examples for axially loaded doublecoped beams are featured in the Fourth
Inflection Point Location
e. in uence of the in ec- “Stability Engineering Journal article point to de nethe Quarter 2016 Generally, of Rectangular Connection Ele■ tion point location increases as the cope ments” (www.aisc.org/ej ). slenderness decreases. For design purposes, it is recommended that e is de ned as This article is a preview of Session C4 “New shown in Figure 4. The pending “Strength Developments in Connection Design” at of Single-Coped Beams” article mentioned NASCC: The Steel Conference, taking place above will provide design recommenda- April 11-13 in Baltimore. Learn more about tions for reducing e under some conditions the conference at www.aisc.org/nascc. for single-coped beams. 20 FEBRUARY 2018
business issues THE BIG CHANGE
What has really changed with marketing in the last 100 years? Just one thing. Really.
BY ANDY SLIPHER
IN 1975, THE FEDERAL COMMUNICATIONS COMMIS- on. It’s all certainly true. But what has enabled nearly every SION (FCC) issued a largely overlooked ruling that allowed bit of it is technology. earth-orbiting antennas—satellites—to be used for broadcastSo proli c is the role of technology in marketing that it ing television over large areas. Around that same time, a little- has become, for some, an alluring distraction. Panic and peer known regional broadcasting network called Home Box Of ce pressure set in, and organizations pursue the latest and great(HBO) took notice and decided to use the FCC’s landmark est technology-based marketing tactics without taking the time decision to begin distributing its own to thoughtfully consider a strategic programming via satellite. approach. As legendary philosopher HBO’s innovative move would and strategist Sun Tzu once put it, have a ripple effect that would spill “Tactics without strategy is the noise A good vision statement over onto the landscape of marketing. before defeat.” Soon, satellite networks proliferated, Marketing must ultimately get the isn’t uff. Rather, it helps and with them, marketers’ ability to product or service into the hands of the target in ways that were never previcustomer—i.e., a real live person. Marall stakeholders reach ously possible. keters need to realize that it is way too Since that time, there has been easy to distract ourselves (via technolso much technological innovation ogy) away from what is centrally imporfor something higher. that marketers are faced with choices tant in marketing: generating a sale to beyond measure. It can be blinding a real person and hopefully repeating and bewildering for anyone charged that process again and again to her or with allocating marketing dollars on behalf of a business. And his delight. Marketing strategy is not so much about a plan but this very issue is what has caused marketers to go awry. This is an rather a system. If you build your marketing (including the sale) age of unprecedented communications, and yet many still strug- around a strategically based, customer-centric system, then techgle to connect with one another. But this is not the real problem. nology becomes a true and valuable tool and not a distraction. The true problem is that too many marketers have failed If you want to plan your marketing communications on a to recognize that only one major thing has changed in marmore strategic level and with a more integrated and seamless keting in the past 100 years: technology. That’s it. Yes, you approach, consider the following methods and means toward now have social media and tweets and follower s and apps and doing so: branding and remarketing and analytics and focus groups Strategic marketing plan. This entails full-on marketing and ROI and CRM and customer personas and digi tal and so guidance—someone asking the right questions and enabling you to think critically about your industry, business, customers, competition, brand and marketing activities. A strategic marketing plan answers both “What are we trying to do?” and Andy Slipheris founder “How are we going to achieve it?” in a thorough, resolute way of Slipher Marketing. He is marketing segment lecturer for Southern Methodist University’s accredited Bank Operations Institute for professional bankers and also for the Independent Bankers Association of Texas. Andy’s forthcoming book isThe Big How: Where Strategy Meets Success. For more information, visit www.slipher.com .
22 FEBRUARY 2018
that doesn’t miss a lick (broad-to-speci c). It facilitates a systematic way of measurably and methodically moving your business’s overall marketing activities from point A to point B. Strategic brand plan.Marketers love to talk branding these days, but few truly understand what a brand is. At its core, a brand is simply a (strong) promise. Everything after that is embodying the promise or not. A brand plan helps an organization answer the why’s and how’s of their brand in a way that actively demonstrates its value.
business issues
Brand landscape.Develop a collaborative document and process that combines visual (graphic/ photographic) and distilled conceptual elements (written) to succinctly express what a particular brand is, and what it is not, to a broader internal audience. At its core, it’s a reference and training document. It serves to familiarize an organization’s management on the concept of their own brand, so that they themselves can more consistently demonstrate and articulate it to others. Vision. Your organization needs to aspire to something greater in order for its marketing to become something that inspires others. Sometimes there is no unifying or inspiring vision—an expression of what an organization hopes to reach or become in the next ve toten years. Other times, a vision reads as at, academic or long-winded. A good vision statement isn’t uff. Rather, it helps all stakeholders reach for something higher. Public outreach strategy.Address and formalize a communications approach for the public-at-large. This does not necessarily mean customers. Rather, it’s about respecting and interfacing with the general public as in uencers, opinion holders, social activists and supporters of personal, political or economic interests. This type of strategy addresses a need for responding to criticism, opposing or competing points of view. Its purpose is to build and demonstrate credibility and to authentically communicate it. In conclusion, plan your marketing. Don’t be led by technology or allow it to distract and overwhelm you. Know who you are, what you want from your marketing and how you’re going to achieve it. Only then will technology become a navigable means to achieve your goals. ■
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conference preview CORE SOLUTION BY BRIAN MORGEN, SE, PE, PHD, RON KLEMENCIC, SE, PE, HON. AIA, AND AMIT VARMA, PHD
A new composite assembly is positioned to set the pace for future high-rise buildings and elevate steel to dominance in core construction.
FOR THE LAST 20 TO 30 YEARS, high-rise of ce building construction has been dominated by a single structural system: reinforced concrete core walls surrounded by structural steel composite oor framing. The reasons for this are many. Concrete walls situated around elevator shafts, exit stairs, restrooms and mechanical/ electrical services offer the bene ts of geometry—all while satisfying the owner’s and architect’s programmatic requirements. Plus, re and acoustical separations, which are easily achieved, and adequate structural stiffness and strength can be readily provided via this solution. Inherent to concrete core wall construction is the cycle time required to set formwork, install reinforcing steel, place embedded plates, install sleeves and block-outs and place and cure concrete before the next level of the core can be constructed. While cycle times vary based on core geometry, reinforcing steel congestion and the skills of the contractors in the geographic location, a common time frame required to construct each core level for a typical tower is three to ve days per oor. On the other hand, erecting the surrounding steel oor framing can occur at a much more rapid pace. Two tiers (four oors) of steel erection per week are possible in many markets, allowing the steel erection to proceed at roughly twice the pace of concrete core construction. This cycle time disparity often delays the start of steel erection. Timed perfectly, the nal steel beams are erected just after the concrete core walls are completed. But consider that for high-rise projects, the difference in pace between the two materials can add up to several months of
extra time required to complete the tower. For owners and developers, this can equate to substantial additional costs in construction loans and contractor general conditions and a delay in collecting rent from building occupants, potentially totaling millions of missed dollars. A New Approach Luckily, a new approach to core construction has emerged. And in fact, it’s currently being implemented as part of the Rainier Square Redevelopment project in downtown Seattle. This approach, a concrete- lledcomposite plate shear wall (CF-CPSW) core system, is commonly referred to as a “sandwich panel wall system” and directly addresses the cycle time disparity. In the case of Rainier Square, a schedule savings of three to four months is anticipated as the entire superstructure can be erected in sequence without the timing restrictions of concrete core construction. The core wall arrangement is identical to a traditional concrete core, providing similar bene ts to owners and architects. Here’s how it works: The system includes prefabricated wall panels and boundary elements comprised of steel face plates, typically ½ in. thick, separated by 1-in.-diameter crossconnecting tie rods spaced 12 in. on center, both horizontally and vertically, with an overall wall assembly thickness varying from 21 in. to 45 in. These panels, which include integrally detailed composite (concrete- lled) coupling beams, are rapidly erected at the same pace as the balance of the steel erection. They are designed with adequate strength and stability
Brian Morgenis a principal and Ron Klemencicis chairman and CEO,
both with Magnusson Klemencic Associates. Amit Varmais a professor with Purdue University’s Lyles School Of Civil Engineering.
24 FEBRUARY 2018
The Rainier Square Redevelopment project in downtown Seattle, currently under construction.
to support up to four oors of steel oor beams and metal decking prior to being lled with concrete, where the face plates serve as permanent formwork for the in ll concrete. The role of the cross-connecting tie rods is critical to the overall performance of the system. The rods serve multiple purposes and provide: ➤ Strength and stability of the un-concreted wall panel to support erection loads Lateral resistance and face plate bracing during the concrete in ll operation ➤ Mechanical connectivity between the steel plates and in- ll concrete forcomposite action leading to enhanced axial and shear strength ➤ Con ned pressure for the concrete for superior seismic performance under ultimate demands ➤ Prevention of delamination modes through the plain concrete in ll ➤ Out-of-plane shear strength ➤ Reduced slenderness of the steel plates Once the panels are erected and the panel-topanel connections are made, a self-consolidating concrete mix is placed in the space between the two plates. The concrete, combined with the steel ➤
plates, theassembly ultimate as strength and stiffness for theprovides core wall a composite section. Shannon Testa, project manager for the project’s general contractor, Lease Crutcher Lewis, highlighted another bene t of the system, saying, “The construction tolerances we typically struggle with between concrete construction and steel construction are eliminated.”
. o C & d a ts n u tR h g ir W
Technical Beginnings Before we discuss the Rainier Square project further, let’s take a brief look back at the sandwich panel system’s hist ory. The system saw its beginnings with a product calle d Bi-Steel, which was originally developed by Corus in the United Kingdom. The product included a patented welding procedure to affi x interconnecting tie rods between two steel plates. The technical advantages of this system were many, but it did not enjoy widespread application, with only a few modest-size apartment buildings in London being constructed. However, the system has been used extensively in the third generation of nuclear power facilities in the United State s and around the world. In this facility type, it is employed as the shield building to provide aircraft impact resistance and also in
Modern
STEEL CONSTRUCTION
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conference preview Professor Amit Varma and his research assistants at Purdue’s Bowen Lab.
internal containment structures to provide adequate strength and stiffness for seismic loading and accident scenarios including impactive and impulsive loadm a e T h c r a e s e R tiy s r e iv n U e u d r u P s te ia c o s s A c i c n e m e l K n o s s u n g a
M
➤Professors
Michael Kreger and Mark Bowman at Purdue’s Bowen Lab.
ing. In fact, AISC hasN690-2012 recently published a speci cation (AISC Supplement No. 1 Speci cation for Safety-Related Steel Structures for Nuclear Facilities ) and a design guide (AISC Design Guide 32: Design of Modular Steel-Plate Composite Walls for Safety-Related Nuclear Facilities ) for this system and associated connections in nuclear construction. (See “Nuclear Option” in the November 2017 issue, available at www.modern steel. com, for more on this design guide.) In order to extend the merits of the Bi-Steel concept to high-rise buildings in high-seismic zones, Purdue University, with funding from the Charles Pankow Foundation, began researching and testing the technology in 2006. Led by professors Mark Bowman and Mike Kreger, the research aimed to investigate a non-proprietary version of an assembly similar to Bi-Stee l. Several aspects of the system were modeled numerically and physically tested, including the stability of the assembly prior to concrete placement, forces in the cross-connecting tie rods and a 3⁄ 8-scale, 5½-story T-shaped wall assembly under cyclic loading. The results of this research can be found in a Charles Pankow Foundation research report, Behavior and Design of Earthquake-Resistant Dual-Plate Composite Shear Wall Systems , and detailed design guidelines are presented in the report Design Procedure for Dual-Plate Composite Shear Walls . The ongoing research at Purdue University under professor Amit Varma, as well as at the University at Buffalo under professor Michel Bruneau, is investigating
M
ag n
us so
26 FEBRUARY 2018
n
Kl e
m en
A diagram of a building core constructed with sandwich panels. cic
As so
cia
te s
conference preview
Sandwich panel core construction vs. concrete core construction. Sandwich panel core being constructed concurrently with steel floor framing.
the performance of: planar sections under varied axial load with alternate crossconnecting tie rod arrangements supplemented by headed studs; more complex wall assemblies including C-Shapes and T-Shapes; coupling beam detailing and performance; and R-factors for seismic design using the FEMA P695 approach. This extensive research program is being funded by AISC and the Charles Pankow Foundation, with in-kind support provided by the Supreme Group. The test set-up and assembly at Purdue’s Bowen Laboratory are being used to test composite walls to combined axial load and cyclic lateral loading up to failure. The parameters included in the experimental investigations are the axial load level (10% to 30% of concrete axial
Magnusson Klemencic Associates
load capacity) and tie rod spacing achieving plate slenderness ratios of 24 to 48. The specimens are ½- to 3⁄8-scale models
A stack of sandwich panels.
Modern STEEL CONSTRUCTION
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conference preview The test set-up and assembly at Bowen Lab are being used to test composite walls to combined axial load and cyclic lateral loading up to failure.
of the prototype walls designed for theme structures located in non-seismic and seismic regions. One emphasis of the project is to develop design details for both nonseismic (governed by wind) and seismic regions, which will become part of the AISC Speci cation for Structural Steel Buildings (ANSI/AISC 360) and Seismic Provisions for Structural Steel Buildings (ANSI/ AISC 341), respectively (both are available at www.aisc.org/speci cations ). Results from initial tests are favorable and will ultimately provide guidance to practitioners in the form of improved design guidelines and acceptance in the AISC Speci cation .
Purdue University Research Team
Fabrication and Erection Challenges Back to the Rainier Square project, the wall panels, typically measuring 13 ft, 9 in. by 37 ft, are being fabricated off-site by Supreme Steel Portland (an AISC member and certi ed fabricator) and shipped in stacked groups. Steel erection is being handled by The Erection Company, who will direct the hoisting, placement and connection of all of the steel elements, including the sandwich panel wall system. The panel system includes approximately 500 panels and 200 boundary elements, as well as installation of up to 240,000 cross-connecting tie rods. The fabrication sequence and the connection of the tie rods are critical to the ef cient and timely fabrication of the panels, and Supreme Steel has devised a process to streamline the fabrication and ensure the quality of the cross-connecting tie-rod connections. Panel-to-panel connections during the site erection sequence are also a critical
detail of the system, speci cally when subjected to the high seismic demands possible in Seattle. Welded connections are being used exclusively at the recommendation of the erector in order to ease eld
A look inside two sandwich panels with different stud configurations.
28 FEBRUARY 2018
conference preview a. Cyclic lateral load – displacement response
b. Envelope of cyclic response P u r d u e U n iv e rs it y R e s e a rc h T e a m
Sandwich panel test results compared to analytical results. Testing a specimen at Purdue’s Bowen Lab.
t-up and speed construction. In addition, project-speci c prequali ed welds have been developed and are being tested to enhance the ef ciency of the connections. The nal assembly will be spray reproofed in order to satisfy the jurisdictional requirements for a three-hour assembly. However, ongoing studies are being conducted to better understand the re performance of the system, with the goal of minimizing or eliminating the need for supplemental re protection for some portions of the system. The ongoing research and testing at Purdue University and University at Buffalo are aimed at identifying further ef ciencies and design enhancements that the sandwich panel wall system can offer. As construction unfolds at Rainier Square in Seattle, there will most certainly be many lessons learned that will bene t future projects considering this system. And if the system is as successful as it’s expected to be, it could very well change high-rise ■ construction as we know it. This article is a preview of Session U5 “Innovative Composite Coupled Core Walls for High-Rise Construction” at NASCC: The Steel Conference, taking place April 11–13 in Baltimore. Learn more about the conference at www.aisc.org/nascc . Purdue University Research Team Modern STEEL CONSTRUCTION
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Vision of the
FUTURE BY MICHELLE BLACK, PE, CHRIS ADAMS, PE, AND SHANE MCCORMICK, SE, PE
Various engineering and science disciplines come together under one roof in a modern, steel-framed research facility with a goal of creating materials of the future.
Michelle Black(mblack@ martinmartin.com ) and Chris Adams
[email protected] ) are
both professional engineers and Shane McCormick(smccormick@ martinmartin.com ) is a principal, all with Martin/Martin, Inc.
30 FEBRUARY 2018
On the northern façade, the glass curtain wall steps in and out while facing Kafadar Commons, the main campus quad and gathering space. Steel takes a decorative form at the west terrace as a threestory trellis, where W6 posts extend from the ground level to just below the roof and connect to W6 beams that tie back to the primary structure.
Sam Nelson
WHILE THE COORS NAME is typically associated with beer, in the case of the Colorado School of Mines, it is also a symbol of innovation and collaboration. The school’s new steel-framed CoorsTek Center for Applied
Sam Nelson
of Colorado. The donation helped fund the new facility’s construction as well as the CoorsTek Research Fellows Program. History Lesson
Science and Engineering features lab and classroom spaces The relationship between the school and the Coors family encouraging interactive, hands-on learning while focusing on (also owners of Coors Brewing Company) began in the 1800s, collaboration between many departments, including physics, and the two continue to have a successful working relationship chemistry, geochemistry, chemical engineering, biological en- to this day. In 1872, Adolph Coors started the Coors Brewgineering, nuclear science and metallurgical and materials engi- ing Company in Golden and launched other businesses as his neering. The state-of-the-art interdisciplinary academic and re- brewing empire grew. One of those ventures began when John search building, which just opened in time for the spring 2018 Herold, an Austrian immigrant and founder of Herold China semester, was made possible thanks to the largest donation in and Pottery Company, leased space from Adolph Coors. While the school’s history—$27 million—from the CoorsTek Corpo- Herold was growing his pottery company, Herman Fleck, head ration, in addition to $14.6 million in funding from the State of the chemistry department at the Colorado School of Mines, Modern
STEEL CONSTRUCTION
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HME, Inc.
Steel framing as seen from the building’s southeast corner.
asked Herold to create ceramic laboratory equipment for use in his research. Adolph Coors soon saw the potential growth of the ceramics market and invested in the Herold China and Pottery Company. In 1915, John Herold left Golden, and the pottery company was solely managed by Adolph Coors, who renamed the company “Coors Porcelain.”
A closer look at the cantilevered corner.
Coors Porcelain produced many commercial consumer products, including scienti c and analytical and lab ware, dinnerware and hotel ware, metals (including developing the rst recyclable aluminum beverage can), consumer products like vases, ashtrays, mugs, golf putters and drivers, cleats, shirt buttons, knife sharpeners and even ceramic armor. In 2000, Coors Ceramics changed its name to CoorsTek and afrmed its mission to “push the frontiers of materials science into the future.” CoorsTek continues to produce advanced labware and ceramic components for many industries including electronics, energy, defense and security, equipment and machinery, food and agriculture, medical and transportation. Consistent Style Upon receiving the donation from CoorsTek, the Colorado School of Mines selected the same architectural team that designed the adjacent steel-framed Marquez Hall (see “Thinning Out” in the September 2014 issue, available at www.modernsteel.com): Bohlin Cywinski Jackson, which has designed several high-pro le university projects across the country, and Anderson Mason Dale Architects, which has designed multiple buildings on the school’s campus. The design team created a modern, 94,000-sq.-ft, four-story, steelframed structure (using approximately 550 tons of steel in all) with an exterior façade consisting mostly of brick and glass curtain wall. On the northern façade, the glass curtain wall steps in and out while facing Kafadar Commons, the main campus quad and gathering space. 32
FEBRUARY 2018
. c n I , E M H
Sam Nelson
The cantilevered section at the northeast corner of the building.
CoorsTek’s donation also funded high-tech equipment purchases, including one of the most advanced electron microscopes in the nation. With vibration performance being a primary design consideration, lab equipment was placed on thick vibration-isolated slabs-on-grade where the space allowed. Lab spaces on steel-framed oors were also expected to receive vibration-sensitive equipment. Because of this, AISC Design
Guide 11: Vibrations of Steel-Framed Structural Systems Due to Human Activity (available at www.aisc.org/dg) recommendations were followed to design a oor structure with a maximum velocity limit of 2,000 micro-in./second. At each lab space, a slab-on-metal-deck consisting of 4½ inches of concrete over 2-in. metal deck spans 10-ft, 6-in.- to 41-ft- long, 27-in.-deep beams spanning to 21-ft-long, 27-in.-deep girders. Modern STEEL CONSTRUCTION
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Sam Nelson
Steel fins on the south f açade mirror those of adjacent Marquez Hall.
Meeting vibration criteria was only the rst of many design challenges for this structure. At the northeast corner of the building, the oor plate extends outward over an open space, leaving the upper three levels of the building cantilevering out from the nearest concrete core wall. The steel framing cantilevers 20 ft north from the core wall, and a perpendicular cantilever extends the oor another 10 ft to the east. For the steel cantilevering from the north face of the core, moment connecting the beams to the core would not suf ciently control de ections. The solution was to add braced frames between levels, effectively creating one large cantilevered frame instead of three levels cantilevered independently. The resulting overturning moment from the frame is carried by the concrete core wall to drilled piers below, and link beams in the east core wall also carry a portion of the force to the south wall of the core.
adhered to the angles protect the glass. Bolts spaced at 24 in. on center through both angle legs and the glass, when tightened, provide a clamping force to hold the glass in place. Plates welded at the exterior of the W8 shape (parallel to the web) create a closed shape capable of carrying torsion induced by wind loading on the ns. The result of this design is that thesteel support is hidden behind the brick veneer, and the viewer at the exterior of the building sees the glass as “ oating” out from the façade. Though the steel support for the glass ns (and much of the primary structure) is concealed, other steel building features were exposed, including the feature stair connecting Levels 1 and 2 in an open atrium overlooking Kafadar Commons. The exposed stair structure consists of built-up steel stringers supporting precast concrete treads and glass panel guardrails. Vibration criteria for the 35-ft span of the stringers necessitated added support at the intermediate landing,
Floating Fins Another unique steel solution arose from the need to support six exterior vertical glass ns projecting from the south façade of the building. With varying dimensions of up to 5 ft by 19 ft, the glass ns required the introduction of W8 posts spanning between the rst and second levels. The posts create a continuous support for the long edge of the ns, carrying the weight of the nsas well as wind loading. Bolted to the south anges of the W8 posts are two back-to-back angles that provide a clamped connection for the glass, and neoprene sheets
though aesthetic concerns led to supporting the landing with beams cantilevering from posts hidden in the adjacent wall. Steel plate caps the bottom of these beams and turns up to form the guardrail at the landing, creating a juxtaposition of steel and glass elements. Steel also takes a decorative form at the west terrace as a three-story trellis, where W6 posts extend from the ground level to just below the roof and connect to W6 beams that tie back to the primary structure. Plates extending through the façade at levels 2 and 3 brace the posts for buckling and lateral load-
34 FEBRUARY 2018
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ing, and closely spaced HSS2×2 horizontal members form the slats that provide shade for terrace occupants. Whether exposed or hidden, structural steel made the signature design components of this building possible. The result is a sophisticated building that not only visually anchors the main quad of the campus, but also signi es collaboration—both between engineering disciplines and between CoorsTek and the Colorado School of Mines. The end design is contextual while also representing the mission of CoorsTek ■ to create materials of the future. Owner Colorado School of Mines, Golden, Colo.
General Contractor FCI Constructors, Inc., Frederick, Colo. Design Architect Bohlin Cywinski Jackson, Seattle Architect of Record AndersonMasonDale Architects, Denver Structural Engineer Martin/Martin, Inc., Lakewood, Colo. Steel Fabricator and Detailer HME, Inc., Topeka, Kan.
Sam Nelson
The feature stair connecting levels 1 and 2.
Interested in business development and making structural steel the material of choice?
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There’s always a solution in steel.
Modern
STEEL CONSTRUCTION
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A new steel art building brings its own sense of style and air to the Stanford campus.
HIGH Art STANFORD UNIVERSITY’S NEWEST BUILDING bucks the trend of the campus’ California Mission style and red tiles roofs.
BY STEVE MARUSICH, SE
action. This layout presented many structural challenges, both gravity and seismic, that required innovative design approaches.
Home to 96,000-sq.-ft the school’s art and art history department, the Floating Diagonal Strands The main structural components are two diagonal strands four-story, steel-framed McMurtry Building brings a modernist touch to the campus’ more traditional that interconnect the roof with the ground oor. Story-deep overall aesthetic and serves as an interdisciplinary hub for the structural steel wide- ange trusses were selected as the most arts that promotes collaboration among students and faculty. cost-effective means of achieving the approximately 175-ft spans Two opposing diagonal strands traverse the building provid- while maintaining the greatest design exibility and openness. ing terraced space for each department, including art studios, The tops of the strands are supported by perpendicular cantiworkshops, editing rooms, screening rooms, faculty of ces and levered diagonal trusses at the third oor to provide the illusion exhibition space. The strands interconnect at the second- oor that the strands are oating. To conform to the overall building library and roof garden to encourage cross-department inter- geometry, the trusses are kinked at the roof level 26° vertically 36
FEBRUARY 2018
The interior courtyard.
A 3D structural model of the building, which uses 1,100 tons of steel.
Framing view from the courtyard, including an interior strand truss.
Iwan Baan, Courtesy Diller Scofidio + Renfro
and 10° horizontally. This necessitated special details to enSteve Marusich sure the stability and constructability of the trusses. The trusses were stick-built in the eld as they were too (
[email protected]) is a principal large to transport fromstories the shop. system of temporary steel pre-assembled shores, up to three tall, A was used to support the truss construction, and these shores also allowed eld adjustment to maintain vertical alignment of the truss chords. Pre-elevation of the strand trusses and perpendicular cantilevered trusses was also used to economize the overall design and offset any de ection of the truss under the full weight of the structure. Surveying performed during construction con rmed the truss de ections closely matched the predicted values.
with Forell/Elsesser Engineers
Modern STEEL CONSTRUCTION
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Iwan Baan, Courtesy Diller Scofidio + Renfro
The 96,000-sq.-ft building from above. Cantilever framing. A wide-flange joint connection at a strand truss.
Since the strand trusses span multiple levels, they tend to act The overall strand truss con guration concentrates seismic as lateral braces. It was determined that seismic demands would drift demands into the rst story, which are typically distributed far exceed the available capacity of the trusses, potentially creat- throughout the height of the building. Controlling the lateral ing an unsafe condition. To relieve these seismic forces, the bot- movement of the rst story was critical tothe design, and bucktoms of the strand trusses were supported by pin assemblies at ling restrained braced frames (BRBFs) were added throughout the second oor and terminate just above ground oor, allowing the oor plate to add stiffness and absorb earthquake energy. the bottom to freely rotate around the pin assembly. The pin To demonstrate that the structure exceeded code requirements detail required careful coordination with the steel fabricator and and Stanford’s performance objectives, the building model was erector to ensure constructability for tolerances and weld access. subjected to a series of earthquake simulations of various mag38 FEBRUARY 2018
One of the strand trusses. The pin assembly is visible at the top-right of the truss. The oculus and rooftop garden. o fr n e R + io d fi o c S
r e l il D y s e tr u o C , n a a B n a w I
nitudes. This advanced nonlinear analysis con rmed that the truss system would behave in a predictable and reliable fashion. In addition, the trusses and braces are architecturally exposed throughout building to provide a sense of scale and give a glimpse at the structural bones of the building, while also highlighting the versatility, strength and beauty of structural steel. Roof Garden and Oculus
A rooftop garden provides quiet places for students and faculty to interact. The landscape design uses a series of curved
concrete planters, lled with native bushes and shrubs as well as large trees, to de ne distinct areas. Cantilevered hardwood seats are integrated into most of the planter walls, and freestanding benches also provide additional seating and serve as pedestrian barriers. The hardwood benches are comprised of stacked wood planks that are vertically post-tensioned together to reduce shrinkage effects from the wood’s high initial moisture content and exterior exposure. At the center of the building, and rooftop garden, is a large oculus that visually connects the various levels and conveys Modern STEEL CONSTRUCTION
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A structural model and detail of the oculus.
natural light to the second- oor library and ground- oor exhibition space. Openness and exibility was critical for the exhibition space, thus necessitating a column-free area, and steel plate girders were used to span the 75 ft between strands at the roof level with the second- oor library hung from below. A complex grillage of secondary steel was also provided around the oculus to support the exterior cladding components. In addition, custom millwork is located around much of the oculus to provide seating and study areas and is integrated with the secondary steel for the cladding to provide a seamless look. The McMurtry with its modern air, contrasts its Building, more traditional neighboring structures yet ts in with them thanks to its complementary façade and similar vertical scale. Its exposed steel framing, thoughtful engineering and sharp angles give a bold new touch to one of the world’s most prestigious institutions of higher learning and make it an appropriate and worthy addition to the Stanford campus. ■
FOR MORE INFORMATION, VISIT TNEMEC.COM/THERMALBREAK OR STOP BY BOOTH #1043 AT GREENBUILD.
Owner Stanford University Aerolon
Tnemec Company’s fluid-applied thermal break co ating, Aerolon,
Uncoated I-Beam
Tnemec Primer
reduces condensation by insulating
Other advantages of Aerolon:
structural members that transmit exterior temperatures through the building
• Corrosion under insulation (CUI) resistance
envelope. Aerolon is a low VOC, waterbased coating that can be easily spray-
• Thermal conductivity (K-Value) of 35 mW/m-K
applied, in the shop or in the field, providing
• Compatible with select fireproofing and sealants
significant cost-saving advantages over structural thermal breaks, limiting design restrictions for architects, and reducing application and labor time for contractors.
40 FEBRUARY 2018
• Excellent substrate bonding and durability • High-build film for faster application
General Contractor Whiting-Turner Contracting Company, Pleasanton, Calif. Design Architect Diller Scofidio + Renfro, New York Executive Architect Bora Architects, Portland, Ore. Structural Engineer Forell/Elsesser Engineers, Inc., San Francisco Steel Fabricators Gayle Manufacturing Company, Woodland, Calif. Olson Steel, San Leandro, Calif. (oculus)
technical sessions networking product showcase • 220+ exhibitors • 4,500 design and construction professionals • 140+ educational seminars
It's the premier event for everyone involved in the design and construction of steelframed buildings and bridges.
registration
NOW OPEN!
NAS CC:
THE STEEL CONFERENCE incorporating the World Steel Bridge Symposium and the SSRC Annual Stability Conference
Baltimore, Maryland | April 11–13, 2018
Sounds clawsome!
www.aisc.org/nascc
A seemingly small structural retro t at the bottom of a prominent Manhattan high-rise brings big gains to occupants and visitors.
Playing to
THE BASE down 75 ROCKEFELLER PLAZA LOOKS
on one of the most famous public spaces in a city of famous public spaces. New ownership recently undertook a full renovation of the landmarked building, and a reimagined lobby now helps extend Rockefeller Center’s pedestrian thoroughfare up to 52nd Street. As part of the renovation, the building’s façade was restored, the existing elevators were replaced and extended, the existing mechanical systems were replaced and multiple new roof terraces were created to upgrade the tower’s of ce oors. A new storefront with bronze mullions and monolithic glass panels invokes the building’s srcinal architectural style. To aggrandize the new thoroughfare, four existing tower columns were removed from the double-height lobby. Three of these columns supported existing transfer girders at the second oor. Each column, carrying between 1,700 and 2,700 42 FEBRUARY 2018
BY JOHN HINCHCLIFFE, PE, JOE MUGFORD, PE, AND RAMON GILSANZ, SE, PE
kips of service gravity load, was part of the building’s lateral system (a steel moment frame with partially restrained connections). The building was designed under New York City’s 1938 building code, which speci ed a much smaller lateral loading than modern design standards like ASCE-7. As such, careful attention was paid to the effects of the new load path on the existing lateral elements, and the overall stiffness of the lateral system was maintained. Multistory trusses and the removal of each column from the top down were among several schemes that were considered for removing the columns before the design team decided to use new transfer girders below the second- oor framing. The new transfer girders run parallel to the existing transfer girders and effectively extend their span to the next column line. The new girders needed to t below the secondoor slab, around the existing built-up transfer girder and
Courtesy KPF of
The newly renovated lobby of 75 Rockefeller Plaza.
Courtesy KPF of
The 33-story, steel-framed building totals 623,000 sq. ft.
( john.hinchcliffe John Hinchcliffe ) is a senior engineer, Joe @gmsllp.com ) is Mugford(
[email protected] an associate partner andRamon Gilsanz ) is a (
[email protected] partner, all with Gilsanz Murray Steficek.
Modern
STEEL CONSTRUCTION
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Courtesy of KPF
A 3D model printed as individual elements, in stages. 1. Column reinforcement and connection plates installed. 2. Half of each box girder installed on each side of existing column. 3. Installation of jacks and load-transfer plates. 4. Column below is ready to cut.
1.
Gilsanz Murray Steficek
k e ic f te S y rra u M z n a ls i G
2.
Gilsanz Murray Steficek
above and between the scalloped architectural nishes of the new lobby ceiling. To meet these requirements, composite box girders were used for the cross se ction of each new transfer. The box shape could be kept tight to the existing transfer girders and within the envelope of the new ce iling. Engaging the slab to develop composite behavior helped minimize the depth and tonnage of each member. The elastic section of the steel shape was designed for the dead load, reduced live 44 FEBRUARY 2018
load and anticipated load that would be induced from the column jacking. The plastic section of the composite shape was designed for the unreduced live load, providing some reserve capacit y. Each new girder was connected to the end of the existing transfer girder with a diaphragm plate that spanned between the webs of the new girder. The existing columns that are part of the new load path were reinforced with single-sided cover
Courtesy of of KPF KPF
The new lobby space f eatures white walls and terrazzo floors. The box girders were jacked at the four columns to be removed.
3.
Gilsanz Murray Steficek
4.
Gilsanz Murray Steficek
plates from the second oor down to the existing grillage foundations. The plates were widened where they meet the webs of each new transfer girder to allow for the new shear connections to be made. Strength and Ductility Requirements for Simple Shear Connections Under Shear and Axial Load by William Thornton was referenced when analyzing moment transfer through the new girder connections. As box girders are more common to bridges than buildings, the American
Association of State Highway and Transportation Of cials (AASHTO) Speci cation was consulted during design in conjunction with the Speci cation for Structural Steel Buildings (ANSI/AISC 360, available at www.aisc.org/speci cations ). The engineer worked closely with the steel fabricator while developing erection and preloading procedures for the new transfers. A scaled 3D model was created—printed as individual elements and attached via magnets—to help commuModern STEEL CONSTRUCTION
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Gilsanz Murray Steficek
The composite box girder scheme coordinated well with the planned sculpted lobby ceiling, which required the transfers to be as narrow as possible.
Gilsanz Murray Steficek
Hoisting a new girder in two segments to surround the existing framing.
Gilsanz Murray Steficek
Box girders, in place.
Gilsanz Murray Steficek
46 FEBRUARY 2018
Gilsanz Murray Steficek
F P K f o y s e tr u o C
C o u tr e s y o f G lis a n z M u rr a y S te ifc e k C o u rt e s y o f G
il s a n z M u r ra y S te ifc e k
The new lobby entrance. 75 Rockefeller Plaza, under construction seven decades ago.
nicate the design concept to the team and the owner. Each girder was fabricated and transported in six pieces that were spliced together in the eld and erected into place. The girders were preloaded to minimize de ection of the existing column above, as well as to minimize any load that would be induced into the existing moment frame as a result of this de ection. Each girder was loaded using two temporary steel yolks that were connected to the webs of the new girder at the location of the existing column to be removed. Jacks were installed between the yolks and the existing column to be removed. The new girders were then pulled down against the column to be removed, which was pushed up. Effects encountered during the preloading, such as axial shortening and resistance from the steel moment frame above, were considered in the structural design and loading procedure. The process was monitored from the initial loading through the nal connection and column removal. This was critical for a successful transfer, as the magnitude of the load and the extent of the existing column elongation meant a visual separation was not achieved prior to cutting the existing column. The newly revitalized tower maintains its historic elegance while providing modern-day amenities and spaces. Thanks to an innovative steel solution, its updated lobby provides an enhanced ability to welcome visitors to one of the city’s most high-pro le plazas. ■ Owner and General Contractor RXR Realty, New York Architect
Kohn Pedersen Fox, New York Structural Engineer Gilsanz Murray Steficek, New York Steel Fabricator and Detailer Orange County Ironworks, Montgomery, N.Y. Steel Erector Gabriel Steel Erectors, Inc., Montgomery, N.Y. The srcinal building was completed in 1947. Modern
STEEL CONSTRUCTION
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BUILDING Up Brooklyn BY JOSEPH SAVALLI, PE, BORYS HAYDA, PE, AND MATTHIEU PEULER, PE
Downtown Brooklyn gets a big boost from a multi-building development that succes sfully interweaves various framing systems.
COOKFOX Architects
sembly of asymmetrical steel beams referred to as “D-Beams” Manhattan, they are also becoming a more regular sight across and is fabricated from a standard rolled wide- ange section and a at bar. It supports a hollow-core precast plank on itsbottom the water in Brooklyn. One of the largest and most prominent new developments in ange. For another DeSimone-designed project employing Downtown Brooklyn is City Point Phase II, a 1.2 million-sq.-ftthis system, see “Mix and Match” in the November 2016 issue, development comprised of a retail podium (using 11,000 tons ofavailable at www.modernsteel.com.) Tower 2 is a at-plate cast-in-place concrete structure with a concrete shear wall core structural steel) and two residential towers. (Phase I is a three-story, 50,000-sq.-ft building to the south of Phase II and opened in 2011.)and slab frames. DeSimone worked closely with the fabricator, Banker, Each of the three structures has a different framing system and is developed by a different entity, which contributed to the throughout the detailing and construction phases of the project. complexity of the design. The podium, which includes numerous This helped anticipate and resolve coordination issues such as
WHILE SKYSCRAPERS HAVE ALWAYS told the story of
big-box, retail anchor tenants, is constructed of structural steel framing with metal deck oors, braced frames and concrete shear walls. The most typical podium bay has W21 or W24 beams spanning 39 ft, 7 in. to W27 or W30 girders spanning 30 ft. The second through sixth oors are occupied by full- oor tenants; the concourse, ground and mezzanine oors house multiple tenants; and the sub-concourse provides required support space with a loading dock and mechanical and storage spaces. Tower 1 is a Girder-Slab structure with reinforced cast-inplace concrete shear walls. (The Girder-Slab system is an as48 FEBRUARY 2018
constructability of complex steel connections and embedding major structural steel elements inside congested concrete shear walls. Architectural Discontinuity Throughout the design and construction phases of the project, the complexity of the architectural design created many structural obstacles. Discontinuity in architectural programming between the three buildings required transferring most tower loads at the podium roof. As a result, Tower 2’s concrete columns transferonto steel plate girders, which are supported by steel columns and con-
DeSimone Consulting Engineers
City Point Phase II is a 1.2 million-sq.ft development comprised of a retail podium and two residential towers.
The project is a prominent addition to Downtown Brooklyn’s growing skyline. Transfer girders at the podium roof.
sr e e n ig n E g n it l u s n o C e n o m i S e D
DeSimone Consulting Engineers
Steel trusses transfer to concrete shear walls in Tower 1.
DeSimone Consulting Engineers
Joseph Savalli( joseph.savalli @de-simone.com ) is a principal, Borys Hayda(borys.hayda @de-simone.com ) is a managing principal and Matthieu Peuler (
[email protected] )
is a senior project manager, all with DeSimone Consulting Engineers.
Modern
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An 84-in.-deep, double-web plate girder required a special truck for transport.
Banker Steel DeSimone Consulting Engineers
Steel-to-concrete connections at a truss. A defining feature of the podium is its two 65-ft-tall by 60-ftwide glass walls.
crete shear walls, and Tower 1’s steel columns transfer onto a grid of steel plate girders. To provide a column-free truck ramp into the podium’s sub-cellar loading dock, additional long-span built-up steel plate girders were needed. The truck ramp required that a large section of Tower 1’s shear walls transfer onto steel trusses, which are in turn supported by steel columns on one side and concrete walls on the other. Because of retail layouts, one of the columns supporting the trusses was transferred again onto an 84-in.-deep, double-web plate girder. This large girder is 36 in. wide, spans 56 ft and weighs 3,000 lb per linear ft (83 tons total), and a special truck was required to transport it. Minor column shifts were accomplished by using sloped columns, with the resulting horizontal forces resisted by the oor framing and the building’s lateral system. The truck ramp wasn’t the only building element requiring transfers. The ground- oor retail promenade that angles through the building required six, 78-in.-deep transfer girders. In addition, the sub-concourse loading dock includes a 90-ft by 180-ft column-free area necessary for semi-trailer maneuvers. This area was accomplished with three 90-ft-long, 46-ft-deep trusses. Connecting large steel transfer beams and trusselements to concrete shear walls proved challenging and required special attention to detailing at the steel-to-concrete interface. Studded steel beams, plates and columns embedded into the concrete walls and pockets in the concrete allowed for these connections. Typically, at the transfer girders, vertical load was transferred from concrete columns and walls to steel plate girders by connecting rebar to welded mechanical couplers. The podium’s lateral system consists of concrete shear walls supplemented by steel-braced frames and moment frames, which provide lateral restraint for wind and seismic lateral loads in addition to loads imposed by sloping columns and the tension glass wall. A portion of the new podium’s lateral force resisting system was connected structurally to an existing adjacent steel building (part of Phase I), and this interface between the two phases consisted of a four-story, laterally braced frame. Bleeding Down A highly intricate podium façade with little repetition necessitated particular attention to spandrel details. Portions of the tower façades “bleed down” into the podium oors, requir ing careful structural coordination between all three project design teams, owners and façadeconsultants.A de ning featureof the podium comprises two, 65-ft-tall by 60-ft-wide glass walls,
COOKFOX Architects
50 FEBRUARY 2018
which are suspended on horizontal post-tensioned cables that span across eachglass wall’s structural frame. The usual construction of a tension glass wall has anchor points at both ends of the horizontal cables. But in this case, since the architectural layout placed the glass walls at the North edge of the building, an alternate anchoring scheme was required. The South ends of the cables are anchored to structural steel members, as is traditionally done, but the north ends of the horizontal cables are attached to a post-tensioned cable spanning vertically and de ecting into a catenary shape,
DeSimone Consulting Engineers
resembling the string on a bow. The catenary cable is anchored Support structure for the post-tensioned glass wall. to a column with 4-ft-long, 7-in.-thick steel gussets. Large post- Each glass wall is suspended on horizontal cables spanning tension forces and stringent de ection criteria required close col- across the structural frame. laboration between the podium structural engineers and the glass wall engineers, and the unbalanced forces required oor trusses and upgrades of the adjacent lateral system to resist the sustained load imposed by the cables. The robust columns required to support the catenary cable assembly weighed as much as 1,150 lb per linear foot, with 7½-in.-thick anges. Today, the City Point mega-project serves as a transformative development to the Downtown Brooklyn community and makes up the largest retail, dining and entertainment destination in the area, thoughtfully contributing to and bolstering an already thriving hub of commerce. ■ Owners Acadia Realty Trust, Inc., New York Washington Square Partners, New York General Contractor ZDG, LLC, New York Architects SLCE Architects, New York COOKFOX Architects, New York Structural Engineer DeSimone Consulting Engineers, New York Steel Fabricator Banker Steel, Lynchburg, Va.
rs e e n i g n E g in lt u s n o C e n o im S e D
Modern
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A steel-framed dining facility and surrounding buildings overcome scheduling challenges to open on time on a fast-growing college campus.
FEEDING Growth BY TARA REEB
Colorado Springs THE UNIVERSITY OF COLORADO Tara Reeb(
[email protected]) is
RK Steel’s marketing coordinator.
(UCCS) is the state’s fastest-growing college. Located in the shadow of the Rocky Mountains on thenorth side of Colorado Springs, the rapidly expanding school was in desperate need of additional student housing. And so the Village at Alpine Valley was developed. Built over two phases, each aligned to nish before the 2015 and 2016 fall school semesters began, the 210,000-sq.-ft, $2.5 million project consists of three new residences halls offering a total of 515 beds. Anchoring the dorms is the new Roaring Fork Dining Hall, a two-story steel-framed indoor and outdoor dining hall and marketplace with a rooftop garden. The 255-ft-long, 131-ft-wide, 33-ft-tall building includes nearly 23,000 sq. ft on the rst oor,
52 FEBRUARY 2018
UCCS’ Village at Alpine Valley comprises three residence halls and a dining hall.
Frank Ooms Photography
The dining hall stands tall with exposed structural steel framing elements and a steel wraparound patio rail.
Bobbi Jo Greenburg, BCER
12,700 sq. ft on the second oor and 3,600 sq. ft on the rooftop terSped Up by Snow race. The facility serves the catering needs not only for the village Roaring Fork was part of the project’s Phase 1, at the beginbut also the entirecampus and features dining spaces, kitchen areas,ning of which the area received 14 in. of snow. While snow is retail space and a large multipurpose room. With a current diningalways expected in a Colorado winter, 14 in. in a short period capacity of 450, it was designed with future expansion in mind. of time is a lot to handle, and construction was stalled by over Thanks to a résumé full of higher education projects, Kiewit a month. In response, Kiewit pushed the schedule into a more Construction Company was selected as the general contractor aggressive mode to ensure the dining hall would be nished for the entire development, and RK Steel was contracted by before the school year started. The expedited schedule caused a Kiewit to fabricate and erect all structural steel and miscella- ripple effect, challenging the entire project team. neous metals for Roaring Fork. While the residence halls were In order to meet the new time constraints, RK Steel hired adprimarily concrete-framed, they did contain signi cant struc- ditional employees to supplement its in-house CAD department. tural steel at the roof levels, and RK also fabricated this steel as This added manpower sped up the detailing process and the team well as all stair and miscellaneous steel for these buildings. was able to submit drawings for not just Roaring Fork but two Modern
STEEL CONSTRUCTION
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Tapered steel beams were designed to provide a signature and sophisticated look to the building.
of the three residence halls as well, all at one time. Fabrication for the dining hall steel was initially bid at a four-week duration, but was reduced to two weeks due to schedule change. As with the detailing, RK boosted its fabrication process as well, setting up a day shift, an overnight shift and overtime on weekends to meet the project demands for just-in-time delivery of prefabricated products. To ensure l e e t S K R
The wraparound patio allows students to take advantage of the fresh Colorado air.
thatprepared the team with followed the strict schedule and was materials on-site, RK used OneNote software to track the status of work orders in the shop using on-site dates for when materials needed to be delivered. The entire project team was able to get real-time updates from OneNote, thus allowing for shipping tickets to be processed immediately. The ripple effect also made its way down the line to RK Steel’s erection crew, whose schedule was reduced from seven to ve weeks. In addition to the heavy accumulation, on the rst day on-site, RK’s erection team was surprised to nd that the foundation had not been completed and that the mason’s scaffolding was hindering the start of steelwork. This delay pushed the start date out an additional 14 days. In order to accommodate this schedule, the erection team increased its hours to 10- to 12-hour days in the eld and overtime on the weekends. Steel was sequenced into small packages to come out to the job site from RK’s shop in sections to allow adequate space for construction equipment as well as minimize the lay-down area. Warp-Free
RK Steel R E C B , rg u b n e e r G o J i b b o B
One of the key structural and architectural features of the dining hall is the series of tapered beams that extrude from the oor. For these W21x55 beams, the web had to be cut at a diagonal, and steel plate of the same thickness and width of the ange was welded back on to make the edge look like the beam was continuous at the diagonal. This presented a challenge when it came to welding the plate. The correct weld lengths had to betoo determined soon as the not plate to warp theweb plate with much heat ange/ members at once. In some instances, part of the welding was completed and then the beam left to cool before additional welding
The village was built in two phases, which opened in time for the 2015 and 2016 academic years, respectively. 54 FEBRUARY 2018
First floor and roof steel for the dining hall, including joists and beams.
was done on the plate ange/ web members. Some test samples were performed prior to fabricating the beams to nd the correct weld pattern so as to prevent warping during the welding and fabrication process. Another challenge involving steel beams occurred at the ceiling of the dining hall— speci cally, the beams W24x55 carrying the glulam connections. Coordination of various widths and locations of the glulam beams and references to their shop drawings had to be taken into account while laying out the saddles on top of the steel beams. Again, welding procedures and tolerances in the shop had to RK Steel be checked and monitored to make sure that the right amount of heat was used to as not to warp the saddle plates or cause the opening to be less than what was needed for the glulam beams to t inside snuggly. Gold Contribution The project was designed to meet LEED Gold certi cation, and RK Steel’s contribution to the application process was to track the recycling and processing facility records of its suppliers. For its part, RK recorded the receipt and acceptance of recyclable content for the project and submitted material tracking records and invoices to the general contractor to assist with LEED certi cation. Phase 1 of the project was completed in time for the beginning of the 2015 fall semester. Phase 2 was also completed on time the following fall. The 515-plus undergraduate students who call the Village home enjoy the easy access to hiking, the recreation center and the rest of the campus. They join the school’s enrollment of 14,000 and counting, all of whom can take advantage of a new steel-framed hub that brings the entire UCCS community together. ■
RK Steel
Heavy snowfall impacted Phase 1 but didn’t keep the project from being finished on time.
Owner University of Colorado Colorado Springs General Contractor Kiewit Construction Company Architect and Structur Engineer Page Southerland Page,alInc., Denver Steel Fabricator and Detailer RK Specialties, Inc., dba RK Steel, Henderson, Colo.
R E C ,B g r u b n e re G o J i b b o B
Exposed steel supports glulam beams and an open floor plan in the dining hall. The diagonal member is part of one of the building’s six braced frames. Modern
STEEL CONSTRUCTION
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RISING to the Challenge BY JOE DARDIS, PE
As the high-rise market continues to grow, so do the opportunities for structural steel in skylines across the country.
by its skyline. of the mid-2000s. High-rise starts a deep the A CITY IS OFTEN DEFINED Recession, bottoming out attook about 1%,dive but during have since The number and height of its high-rise structures commu- Great nicate a sense of accomplishment and economic prosperity— and in most American cities today, the growing number of skyscrapers underscores a trend of people and businesses moving back into dense urban cores. Highs and Lows of High-Rises While cities are certainly on the rise again, high-rise construction (20+ stories) has seen some dramatic changes over the last 25 years. Relative to total square footage of construction starts (nonresidential and residential four stories and higher), high-rise construction starts were relatively stable in the 1990s followed by a peak of around 6% during the economic boom
Joe Dardis(
[email protected] ) is AISC’s structural steelspecialist
for Chicago.
56 FEBRUARY 2018
recovered and peaked at about 6.5% in 2015 (Figure 1). To understand the peaks and valleys, it’s necessary to consider who or what is going into these buildings. With the exception of the early 1990s, multistory residential (MSR) has been the predominant use of high-rise buildings (Figure 2), followed in a distant second by of ce and nally by the occasional healthcare facility or government building. The largest variance between MSR and all other building types occurred in the early 2000s, followed by an almost equal, albeit low-volume, split between MSR and of ce during the great recession. MSR has gained back its dominance in recent years, accounting for roughly 85% of the high-rise market. Looking at Figures 1 and 2 together, there is one strong inference to be made: During economic booms, there is a direct correlation between an increase in the percentage of high-rises relative to the overall construction market. This indicates that the increase in high-rise square footage in Figure 2 isn’t just due the fact that overall square footage is up, but also that we tend to build taller buildings when the economy is humming along. Where are these high-rises being built? Figure 3 shows the total number of high-rise starts by state between 2014 and 2016. It’s no surprise that New York (speci cally, the New York City metro area) is the dominant state for high rise buildings, followed by Florida, Illinois, California and Texas.
Percentage of Overall Construction by Square Footage 20+ Stories 7.00% 6.00% 5.00% s e ri 4.00% o t S + 0 2 3.00% %
2.00% 1.00% 0.00%
0 9 9 1
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STEEL CONSTRUCTION
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income for the owner. (For more on this technology, see “Core Solution” on page 24.) ASTM A913 is hot-rolled structural steel with a yield
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strength of up to 70 ksi and up to 65 ksi without the need for weld pre-heat. This innovation 70 can pay huge dividends in high10 Total Projects rise building design as higher0 174 strength steel allows designers to Steel’s Role incorporate lighter sections into How does steel stack up? The percentage of high-rise con- their projects, reducing overall tonnage on a project. In addistruction using steel as the dominant framing material hovers tion, using A913 can eliminate the use of built-up column secaround 40% to 50%, with a notable drop to the 20% to 30% tions in some scenarios, which can result in big savings when it range during the early 2000s (Figure 4). Putting this together comes to fabrication costs. Lastly, using a lighter column secwith Figure 2 during this same time period, there is a direct cor- tion, particularly at the base of a building, puts less demand relation between the percentage of high-rises using steel and the on the crane. In situations where a heavier column would revariance in occupancy type between MSR and of ce. As the vari- quire a crane with a higher load capacity, A913 can address that ance becomes smaller, as is the case in recent years, the percent- constructability challenge. age of high-rises using steel returns to the 40% to 50% range. A1085, which increases the design strength of HSS from 46 So what’s next for steel in tall buildings? Recent innovations ksi to 50 ksi, can be used as an economical solution in braced like steel plate composite walls and materials such as ASTM frame applications. The increased strength can help reduce 38
1
A913 and building ASTM A1085 steel give steelwalls a legcan up be in high-rise design.structural Steel plate composite used as a lateral system in both high-seismic and high-wind regions. This system provides the strength, stiffness, safety and serviceability of a reinforced concrete core without the negatives of rebar congestion and complex formwork. The core and perimeter steel can rise in tandem, resulting in much faster erection. This leads to a reduced overall schedule, lowered overhead and general conditions costs and earlier rental
overall tonnage on cial a project also isreduce sizes, which can be bene if the and designer tryingmember to t a brace within a wall. In the high-rise world, innovative products and solutions are critical in order to keep pushing the envelope. If current high-rise trends stay consistent over the next few years, the steel industry will have plenty of opportunities to show off the advancements that can make steel the material of choice for your next high-rise project. ■
Figure 4. Percentage of predominantly steel-framed high-rises. 70.00% 60.00% l 50.00% e e t S % 40.00%
30.00% 20.00% 10.00% 0.00%
58 FEBRUARY 2018
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This seminar focuses on the updates in these new publications and will be presented in the following cities in Spring 2018: 2/27 3/6 3/8 3/28 4/20
Sacramento Nashville Denver Philadelphia Omaha (SEAON)
5/4 5/8 5/9 5/22 5/31
Las Vegas (SEAoSN) Dallas Houston Detroit Los Angeles
The Louis F. Geschwindner Seminar Series
presents
The AISC Steel Construction Manual, 15th Ed. and 2016 Specification A 4-hour Continuing Education Event by Louis F. Geschwindner PE, PhD
More information can be found at www.aisc.org/ seminars
All registrants will have the opportunity to purchase the new Manual at a discount price of $125!
There’s always a solution in steel. American Institute of Steel Construction 312.670.2400 www.aisc.org
new products CAST CONNEX DIABLO BOLTED SPLICES
CAST CONNEX Diablo Bolted Splices are cast steel ttings that enable unobtrusive eld bolted splices in circular hollow structural sections (HSS) or pipe members. The ttings are designed such that the bolted connection is inboard of the outer diameter of the member. Using the ttings, splices can be sheathed in thin-gauge plate for concealment or can be left uncovered for a sleek, technical connection aesthetic. The splices are currently available to t round HSS or pipe in the following outer diameters: 6.625 in. (168 mm), 8.625 in. (219 mm), 10.75 in. (273 mm) and 12.75 in. (324 mm). The connectors include weld preps and can be easily welded to the end of a square-cut HSS or pipe member of any typical wall thickness. The cover plates (sold separately) can be secured over the ttings in the eld using low-pro le screws. For more information, visit www.castconnex.com or call 416.806.3521.
STEELMAX BM-7 MULTIPURPOSE COMPACT, PORTABLE BEVELING TOOL
Plate and pipe edge preparation has traditionally been a labor-intensive, dirty and timeconsuming task done with handheld grinders to create an edge suitable for welding or nal painting or coating. The new BM7 handheld beveller from Steelmax is a highspeed, lightweight edge-prepping solution that will enable you to create consistent edges faster and with less fatigue then using any size grind er. This multi-purpose milling tool can bevel, deburr, chamfer and radius mill edges on plate, pipe, tube and holes. The machine can be used on at, curv ed and radiused parts and can countersink holes as small as 13∕8 in. in diameter. The BM7 is an ef cient solution for creating quick and consistent beveled edges for weld preparation, rounding edges for paint and coating preparation and removing burrs from thermal or mechanical cutting processes. For more information, visit www.steelmax.com or call 877.833.5629.
FICEP 9-AXIS PLASMA CUTTING ROBOT
The FICEP Model RAZ plasma robot drives productivity to a level never previously attained. The innovative design incorporates non-contact laser technology to scan the physical parameters of all the surfaces and edges of a structural steel member in seconds. The RAZ is enhanced by powerful software to optimize all cutting routines, and its expanded capability to process all four sides of structural tube and pipe makes it the most powerful and versatile solution available. For more information, visit www. cepcorp.com or call 410.588.5800. 60 FEBRUARY 2018
news EDUCATION
CVTC Installs Teaching Sculpture Chippewa Valley Technical College (CVTC) in Eau Claire, Wis., recently installed a 1.5-ton steel teaching sculpture on the grounds of its Energy Education Center. The sculpture, standing nine feet tall and eight feet deep and wide, consists of a series of galvanized steel beams
vanizing in Winsted, Minn. (an AISC member) which donated its galvanizing services. Then Merrill assembled the parts according to an engineered design based on model designs from AISC. Harris Rebar donated materials for the concrete base and Evan Ber-
However, all materials and labor were donated through the CVTC Foundation, Inc. “This is a wonderful example of how in-kind contributions can directly enhance learning opportunities for students,” said Aliesha Crowe, executive
connected in varying angles with varying connection methods. “The sculpture shows the different ways steel beams can be joined, along with different welds and fasteners,” said Al Spaeth, program director of CVTC’s Architectural Structural Design program. “It will help students visualize the connections they are learning about in the classroom.” “These sculptures were created for their instructional value,” said Keith Vesperman, an instructor in the program. “The rst one was inGainesville, Florida in 1986. Our students were asking for one because they were having trouble visualizing the connections.” Students rst approached Spaeth
glund of Krech Ojard provided engineering review services. Vesperman noted that there are dozens of different steel members, weld groups and connection elements used in steel construction, and while the sculpture doesn’t feature them all, it has the ones most commonly used. “We will absolutely be going outside as a whole class to look at the examples,” he said. “And students will be walking by it every day and can look at it on their own,” Spaeth added. Maeden said fabricated steel usually costs about $3,000 a ton. Considering the number of small pieces involved and all of the other donated labor that went into the sculpture, the total project is worth
director of the Foundation. “We are grateful to our partners at Merrill Steel and other companies who contributed to this project that is a valuable addition to the Energy Education Center grounds and to CVTC’s instructional resources.” There are currently more than 170 such teaching sculptures at colleges and universities around the U.S. Most are outside engineering schools at major universities, bu t there are a few at community and technical colleges. CVTC’s sculpture is the rst at a technical college in Wisconsin. For more about the AISC steel sculpture, including a list of school locations and information on having one constructed on your campus, visit www.aisc.org/
about sculpture 2006, when the program, athen called in Civil Engineering, was about $14,000, he added. located at the Business Education Center. However, logistics problems prevented the placement of a sculpture there. When the program moved to the Energy Education Center this year, CVTC President Bruce Barker gave the go-ahead to pursue the project. Spaeth and Vesperman worked through the program’s advisory committee and the CVTC Foundation to secure donations. The steel fabrication was donated by Merrill Steel of Scho eld, Wis. (an AISC member and certi ed fabricator). “We hire exclusively out of CVTC’s program for our steel detailing group,” said James Meaden, detailing and document control manager for Merrill Steel. “We have about 12 CVTC graduates and try to hire one or two from each graduating class.” Meaden said he approached the company’s three principal owners. “They were all on board in providing a teaching opportunity to the school,” he said. Merrill Steel donated and fabricated the steel and handed it off to AZZ Gal-
steelsculpture.
Modern
STEEL CONSTRUCTION61
news NASCC
2018 NASCC Registration Now Open
People
The 2018 NASCC: The Steel Conference is set to take place April 11–13 in Baltimore. If you’re involved in the design or construction of steel buildings or bridges, this is your oncea-year opportunity to meet more than 4,500 industry practitioners and learn from the leading experts in the steel community, whether it’s an expert on wind design, the author of a design guide on vibration or members of the committee who put together the AISC Code of Standard Practice. In addition, more than 240 exhibitors will showcase the latest products and services ranging from fabrication equipment to structural engineering software. “The industry connections, personal relationships, cutting-edge technology and face-to-face interactions are worth way more than the cost of the entire trip,” said 2017 participant Nyckey Heath, PE, of Bennett Steel, Inc. (an AISC member and certi ed fabricator). “I have met many people who have proven to be valuable
sessions at the SSRC Annual Stability Conference and 26 sessions at the World Steel Bridge Symposium. The conference also includes an Architect’s Program, a tailored collection of more than 50 unique sessions for architects. Participants can earn up to 16 PDHs by attending the conference’s dynamic, expert-led sessions (plus an additional 4 PDHs if they attend an optional preconference short course). This year’s conference also features three keynote sessions—one each day. The rst is on a general topic designed to engage the audience and will feature Dan Goods, a visual strategist for NASA’s Jet Propulsion Lab. The second will feature a presentation from the top-rated speaker from the last decade of The Steel Conference—Duane Miller, PE, ScD, manager,engineering services and welding design consultant at Lincoln Electric. The third is the 2018 T.R. Higgins Lecture, presented by 2018 award winner Robert J. Connor, a professor at Purdue University
• Modjeski and Masters announced that after 41 years with the firm, CEO Barney Martin, Jr., has retired. He is being replaced byMichael Britt, who was promoted to president last year and worked for the firm from 1979 to 1989, left briefly, returned and eventually became an associate in 1997. During his tenure, Martin spearheaded the firm's growth, opening new offices in Philadelphia, Washington, D.C., and Raleigh, N.C., and leading the firm to its first acquisition ever in 2015 when Littleton, Colo.-based Summit Engineering Group, Inc., was acquired. • Gregory D. Shreve, SE, PE , has been appointed by the LeMessurier board of directors as executive vice president. Shreve joined the company in 1984 and was promoted to
resources for me as an engineer, fabricator and erector. This is an investment in your company’s future!” This year’s event will offer more than 130 technical sessions on the latest design concepts, construction techniques and cutting-edge research, including 13
School of Engineering. One low registration fee gains you access to all of the technical sessions, the keynote sessions, the T.R. Higgins Lecture and the exhibition hall. Registration for the conference is now open. For more information, visit www.aisc.org/nascc.
associate in 2000 and vice president in 2008. In addition, Eric M. Hines, PE, PhD , has been appointed to the company’s board. Hines joined LeMessurier in 2002 and was promoted to associate in 2004 and principal in 2010. He is also a Professor of the Practice at Tufts University, where he has taught structural design and guided graduate student research since 2003, thus perpetuating the longestablished culture between academia and profession established by William LeMessurier, when he founded the firm and taught at MIT. • Bridge engineering and supply company Acrow Bridge (an NSBA member) announced that Mark Joosten has been named president of theAcrow Group, in addition to maintaining his role as COO. At the same time, Paul Sullivan has been named the company's senior vice president – international.
62 FEBRUARY 2018
news CERTIFICATION
AISC Releases New Certification Standard for Steel Fabrication, Components and Erection AISC has released a new standard, Certi cation Standard for Steel Fabrication and Erection, and Manufacturing of Metal Components (AISC 207-16). Available for free at www.aisc.org/newcertstandard, this
the new standard simpli es and clari es provisions for program participants and their markets. Owners, DOTs, architects, engineers and general contractors will gain a better understanding of AISC
common requirements in Section One correct this situation and leave any differences among industry segment requirements to their four unique industry sections.”
standard bringsstandards together related provisions four existing to from steel building fabrication, steel bridge fabrication, steel erection and metal component manufacturing. Developed by AISC's Certi cation Standards Committee, the standard harmonizes common components of the existing standards into a cohesive document. The previous standards, developed over a period of years, were dif cult to compare side by side. By combining commonalities of the existing standards,
Certi cation this of improved format. “The signiwith cance the harmonized standard lies in Section One,” said Michael A. West, PE, AIA, principal, Computerized Structural Design, Milwaukee, Wis., and chair of AISC’s Certi cation Standards Committee. “The provisions in it are common to all four industry segments. Because the previous four separate standards were developed over time, minor differences in terminology and requirements have been discovered in the documents. The
certification program tionThe to the new standard will kickmigraoff at NASCC: The Steel Conference (www.aisc.o rg/nascc ) in Baltimore on April 11-13, 2018. There will be three technical sessions on the fabricator certification program migration for building, bridge, hydraulic fabricators and component manufacturers. For questions, please contact AISC Certi cation at certi
[email protected] or 312.670.7520.
MANUAL
15th Edition AISC Manual Companion Resources Available AISC has posted several new resources that complement the 15th EditionSteel
cation for Structural Steel Buildings and the 15th Edition Manual for designing
Edition Manual. This resource provides a complete list of shapes recorded from
Construction Manualare , released thisDesign past summer. Included the v15.0 Examples, v15.0 Shapes Database, v15.0H Historic Shapes Database, Basic Design Values Cards and Interactive Reference List. All are available for free download at www.aisc.org/manualresources. “The practicing engineer or student will nd these up dated resources of great value as design tools, references and learning tools in their day-to-day practice,” notes Cynthia Duncan, AISC director of engineering. T h e v15.0 Design Exam pl es contain more than
members, connections and15.0 structural systems. The new version offers several improvements over the previous version 14.2, including many new member design tables that supplement the Manual with additional material grades, including ASTM A913 Grades 65 and 70 W-shapes and ASTM A1085 HSS members. Also included in v15.0 are new design examples that outline the procedure for satisfying structural integrity requirements—but only when required by the building code—for common connection types. The v15.0 Shapes Database is a Microsoft Excel spreadsheet that compiles the dimensions and properties of all shapes printed in Part 1 of the 15th Edition Manual. All of the 96 new shapes added to the 15th Edition are now included in v15.0 along with several useful dimensions including the “T” dimension and “Workable Gage.” The database now has a built-in Readme le that serves as the glossary for the database along with a complete list of improvements for v15.0. The new v15.0H Historic Shapes Database is updated with all dimensions and properties consistent with the 14th
1873 2010. The Basic Values Cardstopresent some of Design the most frequently used limit state equations for checking members and connections from the 2016 Speci cation in an abbreviated format. The “pocket” size of these cards allows them to be kept on your desk or in your eld notebookfor use in situations where the available strengths for members and connections are needed quickly. The Interactive Reference List is a complete listing of all the references found in both the 2016 Speci cation and 15th Edition Manual. A link is provided (where available) to the location where the listed publications can be obtained. Many of the references are available from the AISC website, while others are linked to the outside organization where the publication can be accessed or purchased. The 15th Edition Manual is available for purchase in hard copy for $200 for AISC members and $400 for non-members. Orders may be placed online at www.aisc.org/publications or by calling 800.644.2400. And for more on these resources, see January’s ManualWise article, “Making the Most of the Manual,” available at www.modernsteel.com.
1 , 6 0 0 pages of examples and tables that illustrate using the provisions of the 2016 Specifi-
Modern
STEEL CONSTRUCTION63
news CONSTRUCTION TRENDS
New Report Highlights Benefits of Hybrid Steel and Timber Construction AISC and Skidmore, Owings & Merrill, LLP (SOM) have released a new report and a video presentation on steel and timber research for mid- and high-rise residential buildings. Structural steel frames have many benefits that complement residential construction, such as prefabrication and speed of construction. These characteristics are similar to emerging technologies such as crosslaminated timber. AISC and SOM partnered to study the combination of these materials as they relate to the challenges of residential construction. The rep ort cov ers the mot ivati ons of this research and a proposed steeltimber composite system for highrise buildings. The proposed system consists of structural steel columns and beams that support a cross-laminated timber (CLT) oor system, creating a at sof t condition. This steel and timber framing system builds on SOM’s
concrete composite construction for a hypothetical high-rise building. The purpose of the testing program was to validate CLT oor systems with a composite concrete topping slab, and the testing program established that the concepts developed by SOM are valid for high-rise buildings. AISC and SOM’s study successfully shows that the comparative steel-timber composite construction system could
also be competitive in the high-rise residential market. The report, AISC Steel and Timber Research for High Rise Residential Buildings—Final Report , and a video presentation by Benton Johnson, SE, PE, senior structural engineer at SOM, titled, Your Next Project Considering Steel & Timber Research for Residential Buildings , are both available for free at www.aisc.org/timberresearch .
Timber Tower Research launched in 2013 with OregonProject, State University, which studied timber-
PUBLICATIONS
Two AISC Publication Drafts Available for Public Review A draft of the 2018 AISC Speci cation for Randolph St., Chicago, IL 60601 by March XL moment connection and expands the Safety-Related Steel Structures for Nuclear 26, 2018. A hard copy is also available for scope of prequali cation for the Chapter Facilities (AISC N690) is now available $15 by calling Rachel Jordan 312.670.5411 11 SidePlate moment connection. for public review. This document is or by emailing
[email protected]. Th e sta nd ar d is av ai lab le at written as a supplement to the 2016 AISC In addition, Supplement No. 1 to www.aisc.org/publicreview along with Speci cation for Structural Steel Buildings ; the 2016 AISC standard Prequali ed the review form. Copies are also availtherefore, the primary revisions are Connections for Special and Intermediate able (for a $35 nominal charge) by conrelated to revisions in that standard. The Steel Moment Frames for Seismic tacting Rachel Jordan at 312.670.5411 or document and public review form are Applications (AISC 358-16) is available by e-mailing
[email protected]. Please available at www.aisc.org/publicreview. for public review until March 2, 2018. submit comments using the forms Please submit your comments This document adds an additional provided online to Margaret Matelectronically to
[email protected] using prequali ed connection, the SSDA thew (
[email protected] ) by March the review comment form, or mail to Slotted Web moment connection, 2, 2018 for consideration. Cynthia Duncan, AISC, Suite 2000, 130 E. updates the Chapter 10 ConXtech Con
64
FEBRUARY 2018
marketplace & employment Structural Engineers Are you looking for a new and exciting opportunity? We are a niche recruiter that specializes in matching great structural engineers with unique opportunities that will help you utilize your talents and achieve your goals. • We are structural engineers by background and enjoy helping other structural engineers find their “Dream Jobs.” • We have over 30 years of experience working with structural engineers. • We will save you time in your job search and provide additional information and help during the process of finding a new job. • For Current Openings, please visit our website and select Hot Jobs. • Please call or e-mail Brian Quinn, PE (616.546.9420 or
[email protected]) so we can learn more about your goals and interests. All inquiries are kept confidential.
SE Impact by SE Solutions, LLC | www.FindYourEngineer.com The Berlin Steel Construction Company is a full service specialty contractor, primarily with structural steel and miscellaneous metals. We design, fabricate, and erect structures in the Northeast and in other parts of the country. We have two fabrication facilities, four erection operations facilities, and six office locations that provide engineering and management of projects. We are a 100% employee owned company (ESOP) with a desire for growth. We service the private commercial, public, institutional, and industrial markets.
Senior Project Manager Structural Steel Division LPR Construction Co. is a respected national construction
company that specializes in complex structural steel erection, industrial construction and mechanical services. We are searching for a Senior Project Manager with a demonstrated ability to manage multiple projects and project managers simultaneously. Ideal candidates will possess strong delegation and problem-solving skills. Additionally, the Senior Project Manager must have the ability to communicate all aspects of a project with customers, LPR executives and site leadership; including P&L, safety, etc. A bachelor’s degree in Engineering, Construction Management or related field is preferred along with six or more years of project management experience. LPR offers competitive wages, full benefits, training programs, job advancement and industry certifications.
Please visit us at www.lprconstruction.com to learn more about career opportunities at LPR and to apply online. You can also submit a resume to: Crystal Kavallieros, Director, Talent Acquisition
[email protected]
LATE MODEL STRUCTURAL STEEL FABRICATING EQUIPMENT Peddinghaus FPDB-2500 CNC Heavy Plate Processor, 96” Width, (3) We are currently looking for experienced applicants for Drill Spindle, HPR260 Plasma, (1) Oxy Torch, Siemens 840, ‘08 #27974 Peddinghaus FPB1500-3E CNC Plate Punch with Plasma, 177 Ton, Estimating Manager Fagor 8025 CNC, 60” Max. Width, 1-1/4” Plate, 1999 #25161 for our Corporate office in Kensington, CT. Behringer HBP-530/1104G Structural Steel Mitre Cutting Band Saw, The Estimating Manager is responsible to provide oversight, 20.8” x 43.3” Maximum Cutting Capacity, 2” Blade, 2000 #27083 leadership and development for the estimating and sales Controlled Automation BT1-1433 CNC Oxy/Plasma Cutting needs of the company by managing internal and exterSystem, 14’ x 33’, Oxy, (2) Hy-Def 200 Amp Plasma, 2002 #20654 nal resources to process bids and proposals. Management Controlled Automation ABL-100-B CNC Flat Bar Detail Line, 143 experience and degree preferred. A minimum of 10 years’ Ton Punch, 400 Ton Single Cut Shear, 40’ Infeed, 1999 #24216 experience specific to estimating, negotiation and sales of Controlled Automation 2AT-175 CNC Plate Punch, 175 Ton, 30” x structural steel & miscellaneous metals fabrication and erec- 60” Travel, 1-1/2” Max. Plate, PC CNC, 1996 #23503 tion is required. Must exhibit strong communication and Controlled Automation DRL344 CNC Beam Dr ill Line, Hem WF140 Saw, Tandem Line, 2008 #24937 proven leadership skills and have experience with common industry software. Salary range for this senior level position is Ficep Gemini 324PG Plate Processor, 10’ x 40’, 15 HP Drill, HPR260XD Plasma Bevel Head, 2014 #28489 negotiable based on skills and experience. Ficep Gemini 36-HD Plate Processor, 12’ x 40’, 35 HP Drill, Interested applicants should submit their resumes to HPR400XD Plasma Bevel Head, 2012 #28490
[email protected]. We are an EOE. www.PrestigeEquipment.com | Ph: +1.631.249.5566
[email protected]
Steel Detailing Manager
Sales Rep Stubbs Engineering, Inc. is looking to hire a full time Steel Detailing Manager for our Las Cruces, NM office capable of managing Are you an independent sales rep? Qnect is looking for a rep multiple employees and projects. Responsible for drafting, model-that has relationships with fabricators, detailers and engineers. ing, and detailing ofvarious projects, coordinating with clients, steel Qnect’s software service is used to optimize projects for erectors, miscellaneous and ornamental metal fabricators. NISDsignificant time and cost advantages. Average savings per job Certification is preferred. Must have knowledge of AISC Detailing/$62/ton. A great way to make your customers happy! Fabrication/Erection Standards. Minimum 5 years’ experience. Email resume to:
[email protected] If you are interested please submit your resume to: www.qnect.com | 413 387 4375
[email protected] Search employment ads online at www.modernsteel.com . To advertise, call 231.228.2274 or e-mail
[email protected] .
Modern STEEL CONSTRUCTION
65
structurally sound
WALK ON THE STYLED SIDE
T e rr i M e y e r B o a k e
WHERE THE MORE PRAGMATIC concerns of safety and economy normally govern bridges, there has been a recent surge in the construction of pedestrian spans driven by high style and innovative design. The Amgen Helix Pedestrian Bridge in Seattle, for example, wrestles with eccentric geometries and loading—using round hollow structural sections (HSS) and plate—to create a dynamic crossing over multiple train tracks. The Helix Bridge is just one of several that will be highlighted in the session “P edestrian Bridges – Invigorate Design Creativity” at NASCC: The Steel Conference, taking place in Baltimore, April 11-13. (Registration is now open; visit www.aisc.org/nascc .) Want to get a sneak peek at this session—and several others? Check out next month’s issue, which will include multiple preview papers for this year’s show as well as the full exhibitor list. ■
66 FEBRUARY 2018
LeMessurier Calls on Tekla Structural Designer for Complex Projects Interoperability and Time Saving Tools Tekla Structural Designer was developed specifically to maximize collaboration with other project parties, including technicians, fabricators and architects. Its unique functionality enables engineers to integrate the physical design model seamlessly with Tekla Structures or Autodesk Revit, and to round-trip without compromising vital design data. “We’re able to import geometry from Revit, design in Tekla Structural Designer and export that information for import back into Revit. If an architect makes geometry updates or changes a slab edge, we’ll send those Tekla Structural Designer, rerun thechanges analysisback and into design, and push updated design information back into Revit.”
Tekla Structural Design at Work: The Hub on Causeway
For over 55 years, LeMessurier has provided structural engineering services to architects, owners, contractors, developers and artists. Led by the example of legendary structural engineer and founder William LeMessurier, LeMessurier provides the expertise for some of the world’s most elegant and sophisticated designs while remaining true to the enduring laws of science and engineering. Known for pushing the envelope of the latest technologies and even inventing new ones, LeMessurier provides solutions responsive to their clients’ visions and reflective of their experience. An early adopter of technology to improve their designs and workflow, LeMessurier put its own talent to work in the eighties to develop a software solution that did not exist commercially at the time. Their early application adopted the concept of Building Information Modeling (BIM) long before it emerged decades later. While LeMessurier’s proprietary tool had evolved over three decades into a powerhouse of capability, the decision to evaluate commercial structural design tools was predicated on the looming effort required to modernize its software to leverage emerging platforms, support normalized data structure integration and keep up with code changes.
Positioning a large scale mixed-use development next to an active arena, a below grade parking garage, and an interstate highway, and bridging it over two active subway tunnels makes planning, phasing and “Tekla Structural Designer has streamlined our design process,” said Craig Blanchet, P.E., Vice Presi- engineering paramount. Currently under construction, The Hub on Causeway Project will be the final piece in dent of LeMessurier. “Because some of our engineers the puzzle that is the site of the srcinal Boston Garden. are no longer doubling as software developers, it allows us to focus their talents on leveraging the features Despite being new to the software, LeMessurier of the software to our advantage. Had we not chosen decided to use Tekla Structural Designer for significant to adopt Tekla Structural Designer, we would have portions of the project. “Relying on a new program for needed to bring on new staff to update and maintain such a big project was obviously a risk for us, but with our in-house software. So Tekla Structural Designer is the potential for time savings and other efficiencies, not just saving us time on projects, it is also saving us we jumped right in with Tekla Structural Designer. It overhead. forced us to get familiar the software very quickly.”
Efficient, Accurate Loading and Analysis Tekla Structural Designer automatically generates an underlying and highly sophisticated analytical model from the physical model, allowing LeMessurier engineers to focus more on design than on analytical model management. Regardless of a model’s size or complexity, Tekla Structural Designer’s analytical engine accurately computes forces and displacements for use in design and the assessment of building performance.
“Tekla Structural Designer allowed us to design the bulk of Phase 1 in a single model,” said Barnes. The project incorporates both concrete flat slabs and composite concrete and steel floor framing. “Tekla Structural Designer has the ability to calculate effective widths based on the physical model which is a big time saver,” said Barnes. “On this project, the integration with Revit, along the composite steel design tures, enabled uswith to work more efficiently. Addingfeathe ability to do concrete design in the same model was a bonus because we had both construction types in the same building.”
“Tekla Structural Designer offers better “Tekla Structural Designer helped this project run integration of multiple materials than more efficiently, and in the end it was a positive experiwe have seen in any other product.” ence,” said Blanchet.
After a lengthy and thorough comparison of commercial tools that would “fill the shoes” and stack up to the company’s proprietary tool, LeMessurier chose Tekla Structural Designer for its rich capabilities that addressed all of their workflow needs. According to Derek Barnes, Associate at LeMessurier, ” Tekla Structural Designer offered the most features and the best integration of all the products we tested. They also offered us the ability to work closely with their development group to ensure we were getting the most out of the software.”
“Tekla Structural Designer gives us multiple analysis sets to pull from, which gives us lots of control. Most programs don’t have the capability to do FE and grillage chase-down. For the design of beam supported concrete slabs, Tekla Structural Designer allows us to separate the slab stiffness from the beam stiffness, so if we choose to we can design the beams without considering the influence of the slab. In the same model we can use a separate analysis set to review the floor system with the beams and slab engaged,” said One Model for Structural Analysis & Design- Barnes. From Schematic Design through Construction DocuBarnes also shared similar benefits with concrete ments, Tekla Structural Designer allows LeMessurier engineers to work from one single model for structural column design. “Tekla Structural Designer does grillage take-downs floor-by-floor, finds the reactions analysis and design, improving efficiency, workflow, and applies them to the next floor. This allows us and ultimately saving time. “Our engineers are workto view column results both for the 3-dimensional ing more efficiently because they don’t need to switch effects of the structure as a whole and from the more between multiple software packages for concrete and traditional floor-by-floor load take-down point of view. steel design. Tekla Structural Designer offers better Doing both has always required significant manual integration of multiple materials than we have seen in intervention, but Tekla Structural Designer puts it all in any other product,” said Barnes. one place. “We reduce the possibility for human error because with Tekla Structural Designer less user input LeMessurier engineers use Tekla Structural is required,” said Barnes. “Tekla Structural Designer Designer to create physical, information-rich models that contain the intelligence they need to automate the automatically computes many of the design parameters, such as column unbraced lengths. The assumpdesign of significant portions of their structures and tions made by the software are typically correct, efficiently manage project changes. but we can easily review and override them when necessary.” TRANSFORMING THE WAY THE WORLD WORKS
“Tekla Structural Designer provided the best fit for our workflow compared to other commercially available software.”
Want to Evaluate Tekla Structural Designer? tekla.com/LeMessurier
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