A I S C 2005

The Engineering Awards of Excellence are presented annually by AISC to recognize engi- EAE neering excellence and innovation in steel-framed . There are four categories based on AWARDS project cost: less than $10 million; $10 million and greater but less than $25 million; $25 million and greater but less than $100 million; and $100 E NGINEERING A W A R D S O F E X C E L L E N C E million and greater. More than one project can be submitted by the same firm and each submittal is considered a separate entry. 2005 JURY ELIGIBILITY — A significant part of the framing system must Benjamin Baer, P.E., S.E. Director of Technology at CRS/New York, where he be steel wide-flange structural shapes or hol- Vice President, Ruben J. Baer & Associates Ltd., oversaw engineering design and production, as well low structural sections. Skokie, IL as architectural production. Ron spent 18 years with the Los Angeles-based Martin Associates Group. He — construction must have been com- Benjamin is the second-generation head of Baer played a leadership role in the Group’s Washington, pleted between January 1, 2002 and Decem- Associates Engineers, Ltd., a DC office, before heading to San Francisco in 1983 ber 31, 2004. firm in suburban Chicago, founded by his father 50 to head their Bay Area office. In 1994, the office — Projects must be located in the U.S., Canada, years ago. Ben is a graduate of the Illinois Institute of became Middlebrook + Louie. Ron is a past director or Mexico. Technology with a BS in Civil Engineering, a licensed of the Structural Engineers Association of California — Both new buildings and renovations (major Professional Engineer in seven states, and a licensed (SEAOC), and a past president of the organization’s retrofit, expansion, or rehabilitation) projects Structural Engineer in Illinois. He is an active mem- northern body (SEAONC). are eligible. ber of the Structural Engineers Association of Illinois (SEAOI), the National Council of Structural Engineers JUDGING CRITERIA Associations, and the Structural Engineers Founda- Larry E. Whaley, P.E. — Creative solutions to the project’s program tion. He is also a member of the Structural Engineering President, Haynes Whaley Associates, Houston requirements Licensing Board for the State of Illinois. Larry is one of the founding members of Haynes — Application of innovative design approaches Whaley Associates. He directs the firm’s administra- in areas such as connections, gravity sys- tive and marketing activities, and leads it in striving Ronald F. Middlebrook, S.E. tems, lateral load resisting systems, fire pro- for creativity, sound engineering, and team collabo- Principal, Middlebrook + Louie Structural Engineers, tection, and blast. ration. Larry’s education includes a Master of Science San Francisco — Use of innovative construction methods such in Engineering, Rice University, 1971 and a Bachelor as EDI, design-build, or advanced computer During most of the 1970s, Ron worked with the of Science in Civil Engineering with Highest Distinc- modeling pioneering A/E/C firm of Caudill Rowlett Scott, tion from the University of Kentucky in 1968. He — Significance of engineering achievement and managing the structural engineering department at has over 30 years of experience in the planning and elegance of design their office in Houston. Later he served as design of building structural systems.

2005 AWARD WINNERS LESS THAN $10M $25M OR GREATER, BUT LESS THAN $100M NATIONAL WINNER NATIONAL WINNER Desert Bloom Porte Cochere—Cabazon, CA William J. Clinton Presidential Center Museum Building—Little Rock, AR MERIT AWARD MERIT AWARD Davis Conference Center—Layton, UT Jay Pritzker Pavilion—Chicago MERIT AWARD $10M OR GREATER, BUT LESS THAN $25M University of Chicago Graduate School of Business—Chicago NATIONAL WINNER The University of Arizona Large Binocular Telescope Enclosure— $100M OR GREATER Mount Graham, AZ NATIONAL WINNER MERIT AWARD Seattle Central Library—Seattle St. Martin’s Episcopal Church—Houston MERIT AWARD MERIT AWARD The Adaptive Reuse of Soldier Field—Chicago Robert Hoag Rawlings Public Library—Pueblo, CO MERIT AWARD St. Luke’s Hospital Cardiac Center and Patient Tower—Milwaukee

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

$100M OR GREATER NATIONAL WINNER Seattle Central Library Seattle

Photo by Lara Swimmer.

JUROR COMMENT he Seattle Central Library is ity loads. The trusses are supported by an elegant in form fol- carefully positioned sloping that “Very inventive solutions lowing function. The project’s maximize counterbalancing opportuni- in structural steel to architects organized the ties, with platforms cantilevering as much meet complex structural library’s programmatic require- as 52’. The second system, the diamond- mentsT into five independent, yet con- shaped steel grid, forms the building’s challenges.” nected, “platforms” which were vertically exoskeleton. The steel grid provides the stacked, offset to maximize surrounding building’s lateral system, interconnects views, and enclosed in a steel-and-glass the platform trusses, serves as the inte- wrapper. This transparent package was rior architectural finish, and supports the delivered to the structural engineers with building’s glass curtain . a demanding set of rules: use no columns Specially designed slip connections in the corners, no vertical columns, and laterally join the steel grid to the platform as few columns as possible. In essence, trusses. The connections merge the two the project’s success depended on mak- structural systems while preventing the ing a 12-story, all-glass building — in transfer of gravity loads into the grid. UBC Seismic Zone 3 — appear to “float” This kept the grid slender, eliminated without support. the need for fireproofing of the grid MKA’s solution (working with Arup steel, and, most importantly, retained the during schematics) was two separate, desired aesthetics. Full-scale mockups layered structural systems. In the first of the connections were built and tested, system, multi-story-deep perimeter plat- and the connections were fully modeled form trusses carry the building’s grav- in 3-D.

Modern Steel Construction • May 2005 hoto courtesy P hoto courtesy Magnusson K lemencic As soci ates.

Structural Engineers Magnusson Klemencic Associates, Seattle Arup, Los Angeles, London, San Francisco, and New York offices (design development and schematics) Engineering Software SAP2000 Architects Office for Metropolitan (OMA), Rotterdam, the Netherlands LMN Architects, Seattle Detailer BDS Steel Detailers, Mesa, AZ, AISC member, NISD member Action Steel Detailing, Inc., Mesa, AZ, AISC member, NISD member Detailing Software Xsteel Fabricator Canron Western Constructors, Inc., Portland, OR, AISC member General Contractor Hoffman Construction Company, Portland, OR

Photo by Michael Dickter, Magnusson Klemencic Associates.

May 2005 • Modern Steel Construction ates. soci lemencic As Magnusson K Graphic courtesy

The exoskeleton was designed so most directly from points of maximum built for significantly less than most recent that a common grid steel member size stress to the nearest support main city libraries. Designed for function (W12×22) could be used throughout the ➜ Utilizing sloping gravity columns and aesthetics, the building also incor- structure. Diamond shape and size were in line with the plane of the seismic porates many sustainable elements. The optimized at 4’ per side and 7’ high based grid. Seattle Central Library applied for and on plate glass availability, most efficient Inside the 412,000-sq. ft building, a received “Silver” certification from the fabrication, and desire to eliminate the structural “book spiral” provides a contin- U.S. Green Building Council (USGBC), need for secondary mullions. The com- uous for the library’s nonfiction col- becoming one of the largest buildings to mon size also facilitated prefabrication of lection. The spiral required the creation receive a Leadership in Energy and Envi- the structural steel grid in “ladders” up to of a gradually sloping switchback ramp ronmental Design (LEED) certification. 85’ tall, greatly simplifying construction. system spanning four , accessible While the project’s design and engi- Three solutions were developed for to all ages and abilities, able to support neering achieved notable reductions in areas within the grid requiring reinforce- heavy bookracks, supported by minimal cost, they also helped lead to one signifi- ment: columns, and economically constructed. cant increase—library usership. Circula- ➜ “Strongbacking” the steel grid with Other unusual features include a nine- tion of materials is up 50%, the number an additional layer of grid in a shape story through the center of the of library cards issued has increased reflecting the exact pattern and loca- building, a meeting level with tomato-red 500%, and attendance is 50% higher tion of stress demands curving , and a children’s area with than anticipated for the first year.  ➜ Sparingly inserting angled transverse playfully sloping columns. “intervention” columns to carry loads At $273 per sq. ft, the new library was

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

$100M OR GREATER Adaptive Reuse of Soldier Field MERIT AWARD Chicago

ome to the Chicago Bears, Soldier Field is the oldest stadium in the National Foot- ball League. Because it had crumbling infrastructure, Houtdated facilities, and no club seating, the Bears decided to redevelop the sta- dium. However, with only 600’ between the existing , it fell more than 100’ short of accommodating today’s conventional football stadium. The architectural solution was an asymmetrical design with general admis- sion seats on one side of the stadium and stacked luxury suites atop two can- tilevered club decks on the other. That . configuration, a first in NFL stadiums, saved just enough space to fit a 61,500- seat stadium inside the colonnades. Completing the design and translat- omas etti Group ing it into a finished product within the required time frame raised the degree

Structural Engineer Thornton-Tomasetti Group, Chicago P hoto courtesy Thornton-T Engineering Software SAP2000 Ramsteel AutoCAD Owner Chicago Park District—Department of Planning & Development Architects Lohan Caprile Goettsch Architects, Chicago Wood + Zapata, New York Fabricator Hirschfeld Steel Company, Inc., Irving, TX, AISC member Erector Danny’s Construction Company, Inc., Gary, IN, AISC member, NEA mem- ber General Contractors Turner Construction Co., Chicago Barton Malow Co., Southfield, MI Kenny Construction Co., Wheeling, IL

Graphic courtesy Lohan Caprile Goettsch Architects and Wood + Zapata.

May 2005 • Modern Steel Construction of engineering difficulty considerably. Many of these breakthroughs were frame. Sixty-four accelerometers were The Soldier Field project schedule was made possible by the stadium’s 13,000- attached to the grandstand to monitor 20 months, with less than one month to ton structural steel frame, which provided its movement. When crowd movement demolish the existing grandstands. great design flexibility. However, the steel causes the structure to vibrate and the While the old stadium rested on 10,000 frame of the upper grandstand cantile- TMDs are tuned to vibrate at the same timber piles driven through landfill to an ver presented another challenge—main- frequency, the two structures move out average depth of 62’, supporting the new taining spectator comfort amidst syn- of phase, dissipating energy and vibra- stadium required 2,000 H piles driven 90’ chronous crowd movements of fans or tions. to 100’ down to bedrock. concertgoers. Because a bare steel and Finite-element modeling software Stadium seats are supported on pre- concrete structure has little natural damp- was used to model the structure and cast concrete risers. The risers span ing to diminish vibrations, a crowd mov- the crowd’s forcing function on it, and to between and are supported by main ing at the structure’s natural frequency determine the placement of the TMDs. structural steel rakers that are supported could create vibrations that were notice- To confirm the theoretical results of the at 40’ centers. The rakers supporting the able to spectators. A dynamic analysis modeling, a custom “Vibration Shaker” upper grandstand cantilever 60’ over the showed that while structural stability was was attached to various locations on the historic colonnades, one of the longest not an issue, vibration and acceleration grandstand. The shaker operated by such cantilevers supporting crowds. To in a packed stadium could reach inten- rotating two sets of weights in opposite keep this seating at a comfortable ele- sities uncomfortable to spectators in directions to induce a measurable vibra- vation and distance from the field, yet the grandstand. The typical solution of tion into the structure. This test confirmed avoid touching the existing west colon- adding more columns was impossible the frequencies at which resonance nade, a tapered, built-up plate girder because of the colonnades below the would occur and assisted in tuning the was designed that is approximately 7’ at cantilever. TMDs. With the TMDs operating in place, its maximum depth. To provide the needed vibration con- the accelerations remain within the limits The structure of the suites were tilted trol, the engineers incorporated 21 tuned for spectator comfort. 14° toward the field, bringing the upper mass dampers (TMDs), located at the tips Read more about Soldier Field in levels of seats closer to the field, thereby of the cantilever of the grandstand. The “Field Goals” in the July 2004 issue of providing better sightlines. Two massive TMDs, about 20 tons each, comprise a Modern Steel Construction, available video boards, 84’ long by 23’ high, attach concrete mass supported on air springs, online at www.modernsteel.com.  to cantilevered steel trusses extending tunable steel springs, and a tunable vis- 100’ in space over the end zones. cous damper connected to the structural

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

$100M OR GREATER MERIT AWARD St. Luke’s Hospital Cardiac Center and Patient Tower Milwaukee

Photo by David Anderson. he Cardiac Center and Patient piers and 85’-tall, unbraced columns Tower, a 430,000 sq. ft, $187 were placed from the of the parking Structural Engineer million addition to St. Luke’s by a 65-ton drill rig. The rig drilled Graef, Anhalt, Schloemer & Medical Center in Milwaukee, the piers and placed the columns while Associates, Inc., Milwaukee has been dubbed “the hospi- traffic moved safely through the garage. Engineering Software talT on stilts.” With the first of eight floors Above grade, the majority of the new RAM Structural beginning seven stories up, it straddles a structure is supported by 32’-deep steel Visual Analysis multi-level parking garage and connects trusses which bridge the west portion of with the existing hospital. The project’s the parking structure, supporting the steel Owner major challenge was erecting the 12-story framing above. Due to the long required St. Luke’s Medical Center, Milwaukee steel superstructure over and through an reach of both tower cranes, the maxi- Architect existing parking garage that remained mum pick at longest reach was nine tons, Kahler Slater Architects, Milwaukee operational. thereby limiting the weight of any single By significantly widening the space truss piece. Detailer between columns and preventing column Construction of a nuclear medicine Pacific Drafting, Inc., Carson, CA, contact with the garage, the design sup- addition directly below the west half of AISC member, NISD member ports the hospital above and allows for the parking structure required the patient Detailing Software uninterrupted traffic flow in the garage tower to clear span 130’ over half the CDS Asteel below. Each column is encased by a parking structure. In order to best use the .5”-thick steel jacket. The column jacket space between trusses, the mechanical Fabricator serves a two-fold purpose: one, as a stay- level was placed on this first supported Merrill Iron & Steel, Inc., in-place form, and two, as protection from level. The four large mechanical units Schofield, WI, AISC member vehicular impact or explosion. A total of 33 used to serve this addition are 28’-tall, Erector columns support the new structure, 14 of which set the truss depth at 32’. A mez- AREA Erectors, Inc., Rockford, IL, which penetrate the parking structure and zanine floor was added to a portion of this NEA member are completely isolated from it, preventing level, requiring horizontal framing at the the transference of vehicular vibrations to truss’s mid-depth. A K-truss configuration General Contractor the patient tower above. was used to reduce the weight of indi- Oscar J. Boldt Construction Co., To perform the column work, drilled vidual chord and web members, allowing Waukesha, WI

May 2005 • Modern Steel Construction the members to comply within the tower used, significantly minimizing field fit-up as a number of sharply skewed connec- crane’s maximum load capacity. problems. tions. W14 members up to W14x730 were In the erection of the trusses, a series The seventh floor of the superstruc- used for chords (65 ksi) and webs (50 of 7’-deep temporary trusses were used to ture, which is supported off the top chord ksi). Members were oriented with flanges support the bottom chord off the new col- of the trusses, the cardiovascular parallel to the truss plane to reduce the umns and parking structure. The trusses operating . This use requires maxi- weak axis unbraced compression length were first erected two in tandem to pro- mum isolation from vibration. Because to half the truss depth. This also allowed vide stability for the webs and top chords. the mechanical floor is directly below the use of both flanges for connections Once a truss was stable, the temporary the operating floor, all mechanical to double gusset plates. Analysis of the truss was removed, re-fitted for adjacent ducts, pipes, conduits, and other compo- trusses considered continuity and redun- spans, and re-used. The trusses were pro- nents that could transmit vibration could dancy in the extent of a catastrophic load vided on four parallel column lines about not be hung directly from the steel sup- such as an explosion or fire in the park- 40’ apart. The top of the trusses formed porting the floor. A system of isolated HSS ing garage below. Resulting bar forces in a rectangular tabletop. This provided a columns supporting an additional frame- chords were up to 3,000 kips. Connec- stable working platform for erection of the work of beams supports this equipment tion plates were up to 2” thick, 8’ x 10’ in eight hospital floors above. independently. Vibration modeling done size and required over 300, 1”-diameter Above the truss system, the configu- before and testing done after completion A490X bolts. To fabricate the truss mem- ration of the patient rooms is rectangular of the structure indicated that vibration bers and gusset plates, software that inte- with a curved, concave exterior wall. The isolation efforts were successful.  grated shop drawing layout dimensions resulting column layout requires a sig- to automated fabricating machines was nificant number of transfer beams as well

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

$25M OR GREATER, BUT LESS THAN $100M NATIONAL WINNER William J. Clinton Presidential Center Museum Building Little Rock, AR helps Program Management. P helps Program Photo courtesy Photo courtesy Polshek Partnership Architects. JUROR COMMENT “Innovative structural design that blends well with the surroundings.”

he William J. Clinton Presiden- boxes, measuring 30” deep and 16” tial Center, located in a park wide. The architecturally exposed box- Structural Engineer along the Arkansas River in shaped built-up diagonals of the build- Leslie E. Robertson Associates Little Rock, AR features innova- ing are kept at an outside dimension of (LERA), RLLP, New York tive connections and exposed 16” x 16” throughout. The decision to Engineering Software structuralT steel in its Museum Building. make the chords and the diagonals the ETABS Reminiscent of nearby train trestles, same width was driven by architectural RISA-3D the building’s five-story steel structure, concerns and also allowed for relatively measuring 420’ long by 46’ wide, is sup- simple connection details that facilitated Owner ported by a pair of 37’-deep trusses. The fast-paced construction. Clinton Presidential , Little trusses cantilever 90’ at each end of the At the north end of the building, the Rock, AR building and are supported at three loca- trusses are supported on a Vierendeel Architect tions with a maximum clear span of 150’ frame-type steel pier structure made up Polshek Partnership LLP, New York between supports. of box-shaped built-up members, form- The museum’s main floor, which sup- ing a moment frame. The pier is capped Fabricator and Detailer ports both the mezzanine level above by a 95-ton transfer girder that measures AFCO Steel, Inc., Little Rock, AR, and the mechanical level below, frames 12’ deep, 3’ wide, and 48’ long. This AISC member, NISD member into the truss bottom chords. These bot- transfer girder cantilevers in both direc- Detailing Software tom chords are built-up from steel plates tions to support the trusses. A special AutoCAD to form boxes that measure 26” deep and pin-support detail was developed atop 16” wide. Similar to the bottom chords, the transfer girder to allow for rotation of Erector the truss top chords receive the roof the primary trusses without inducing sec- Derr Steel Erection Co., Euless, TX, framing, which in turn supports a private ondary stresses into the pier. AISC member retreat for the Clinton Foundation located To accommodate architectural and General Contractor at the top of the building. Like the bottom mechanical considerations, the pier CDI Contractors, LLC, Little Rock, AR chords, the top chords are built-up steel structure is located off center with respect

May 2005 • Modern Steel Construction Photo courtesy Phelps Program Management. to the building’s center of gravity. The bottom of the curtain wall mullions while from foundations cast below the plaza resulting twisting forces are delivered to allowing for vertical sliding, thereby paving. The result is a lightweight and the building’s shear walls by horizontal allowing the to move indepen- transparent canopy. trusses located in the floor diaphragms dently of the curtain wall. Steel structure made possible this at both the top and bottom chord levels. For the western façade, double open and accessible building that The horizontal trusses in the floor framing wall construction was used with the reflects President Clinton’s aspiration at the top and bottom chord levels act as outer curtain wall cantilevering from to “put things in the light.”  collector and drag members that deliver the western face of the building. The lateral wind and seismic forces to the resulting separation forms a space building’s shear walls. They also act to containing exterior and provide stability during construction prior museum areas that are shaded from to the casting of the composite concrete the sun. floor diaphragms. The goal for the entrance canopy Vertical built-up box mullions, hung was to provide a minimum structure from the built-up box-shaped cantilever where each part of the canopy is beams, carry both the balconies and the called upon to do work. Here, glass is curtain wall. The lower level balcony is configured to cantilever out from steel supported by beams cantilevering from bars that pivot from a round bar. The the bottom chord of the truss. These columns supporting this bar are sim- beams provide lateral support at the ple plate structures that cantilever up

Graphic courtesy Leslie E. Robertson Associates.

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

$25M OR GREATER, BUT LESS THAN $100M MERIT AWARD . Photo by Peter Barreras

Jay Pritzker Pavilion Structural Engineer Chicago Skidmore, Owings & Merrill LLP, Chicago he Jay Pritzker Pavilion in Chi- ture of the shapes to take advantage of Engineering Software cago’s Millennium Park houses the inherent geometric stiffness of each SOM AES software an orchestral stage area form. S-FRAME framed by enormous metallic The basic structural system concept SAP2000 forms designed and placed was developed and refined using com- Architect toT improve the outdoor venue’s acoustic puter-based surface modeling. First, a Gehry Partners LLP, Los Angeles characteristics. structural working surface was generated The pavilion is composed of a south- 2’ behind the clad surface. Vertical slic- Detailers facing bandshell housing the stage and ing planes at 9’-8” centers and horizontal Dowco Consultants, Ltd., related support facilities, which in turn planes at 10’ centers were electronically Burnaby, British Columbia, Canada, support the metallic forms. The central passed through the structural working AISC member, NISD member portion of the bandshell roof cantilevers surface. The intersections created the Industrial Detailing, Inc. (trellis), up to 100’ beyond the proscenium . structural work points. Straight line seg- St. Louis, AISC member There are a total of twelve individual ments connecting the work points formed metal-clad assemblies arranged around an electronic wireframe representing the Detailing Software and above the central stage, forming an centerlines of the structural grid/frame Tekla Structures overall composition some 300’ wide by members. SDS/2 (trellis) up to 120’ tall. Behind the upper metal For this type of structure, with relatively Fabricators surfaces, a system of inclined steel pipe few (450) steel tons, considerations other Lejeune Steel Company, struts connected to the bandshell struc- than least weight were far more important Minneapolis, AISC member ture stabilizes the metal elements. in terms of overall economy. To promote A steel grid/ribbed frame concept was repetition and control of steel connec- ACME Structural, Inc. (trellis), developed for the support of the metal tion detailing and fabrication, as well as Springfield, MO, AISC member elements, which proved to respond well coordination with cladding systems and Erector to the diverse structural system require- attachments, member sizes were stan- Danny’s Construction Company, ments of the project. The structure was dardized throughout the metal elements. Shakopee, MN, AISC member configured to closely follow the curva- Independent, parallel structural analysis

May 2005 • Modern Steel Construction and design checks were done using two commercially available software pro- grams, S-FRAME and SAP2000, for a complete loading regime including wind, temperature, snow, ice, and live load. The drawings, together with the com- puter wireframe, were issued to the con- tractor as part of the project documen- tation. The steel detailers converted the wireframe electronic data into Xsteel for use in the preparation of shop drawings for the structural steel. The fabrication/ erection concept was to prefabricate vertical sections of each metal element in the shop, trial fit and pre-assemble each section to neighboring sections in the shop, prepare the members for shop painting, and ship them to the site. A 625’ by 325’ shell-shaped trel- lis structure, formed by arched steel pipes, defines the audience space and connects the stage to the great lawn. The trellis structure supports a system of speakers, eliminating the need for speaker towers. Read more about Jay Pritzker Pavil- ion in “Music in the Park” in the August 2004 issue of Modern Steel Construction, available online at www.modernsteel. com. 

Photo by Peter Barreras.

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

$25M OR GREATER, BUT LESS THAN $100M MERIT AWARD

University of Chicago Graduate School of Business Hyde Park Center Chicago

Photo courtesy Feinkopf Photography. he University of Chicago Structural Engineer Detailer Graduate School of Business Thornton-Tomasetti Group, Chicago LTC, Inc., La Crosse, WI, AISC mem- opened its new Hyde Park ber Structural Engineer Sub-Consultant Center in September 2004. The Dewhurst MacFarlane and Partners, Detailing Software 415,000 sq. ft academic facil- ityT is comprised of a base building with New York DetailCAD AutoCAD five above-grade levels and two below- Engineering Software grade levels, and a glass-enclosed RAM Structural System Fabricator and Detailer Winter Garden. The complex features SAFE Zalk Josephs Fabricators LLC, Stough- 12 classrooms, 31 group-study rooms, FloorVib 2 ton, WI, AISC member faculty offices, computer labs, multipur- SAP2000 Erector pose rooms and an underground park- Owner AREA Erectors, Inc., Wheeling, IL, NEA ing garage for 170 cars. University of Chicago Graduate School member In total, the base building used of Business, Chicago approximately 3,000 tons of structural General Contractor steel, of which 500 tons were plate Architect Turner Construction Co., Chicago girders. The lateral system consists Rafael Viñoly Architects, PC, New York of braced framing located around the cores within the base building “square,” as well as one braced frame in the southeast wing. The base building’s lat- eral system is independent from that of the Winter Garden at the ground floor.

May 2005 • Modern Steel Construction Photo courtesy Feinkopf Photography.

To isolate the systems, ground-level at Lower Level 1, and diagonal bracing assembly were installed using coun- bridges that link the base building to hidden in a demising wall of this level tersunk high-strength screws tapped the Winter Garden are on slide bearing braces the columns at the ground floor. directly into the mullions. At the fourth connections. The columns rise nearly 43’ above the floor, sloping beams support a glass The design called for massings to ground floor as a vertical cantilever. skylight and brace the Winter Garden project over the building entrances They were fabricated in two sections, wall back to the floor diaphragm of the below. The resulting cantilevers ranged with the column splices hidden within base building. from 3’ to 42’ and required over 600 the ground floor slab. Resistance to lateral loads is pro- moment connections. The cantilevers The eight pipes of each main column vided by three systems: the cantilevered were often supported by transfer col- branch out to become roof rafters. The main columns, out-of-plane bending umns, while non-typical deflections rafters curve to form intersecting Gothic of the perimeter wall mullions, and the were accommodated into the design , which create roof “funnels.” As in-plane rigid tube frame (mullions and and installation of the cladding. Spacer they rise nearly 40’ above the tops of transoms) of the perimeter walls. posts were used at the perimeter of the columns, the rafters taper from an Read more about the Hyde Park Cen- projecting massings to limit differential outside diameter of 9” to just 6”. They ter and Winter Garden in “Class Act” in deflections between floors. support continuous purlins spaced the November 2004 issue of Modern More than 100 column transfers approximately 6’ on center. The purlins, Steel Construction, available online at were required to achieve the column- rectangular tubes with outside dimen- www.modernsteel.com.  free spaces in the center’s multi-func- sions of 6” by 3”, support the roof glaz- tion room and the lower-level class- ing and provide bracing for the slender rooms and parking levels. Plate girders rafters. The four roof funnels, one cen- varied in depth from 30” to 73”, depend- tered on each of the four main columns, ing on architectural requirements, and are interconnected to form the 96’ by 96’ weighed from 283 to 1,528 lb per lin- roof. ear foot. When service reaction loads The third floor of the base building for plate girders exceeded reasonable cantilevers out 12’ to support the glass design limits for shear connections, a walls that enclose the Winter Garden. bearing connection was used to elimi- Wall framing consists of 14” by 3” hollow nate the effects of the eccentricity on mullions fabricated from 3/4” steel plate the support column. and 4.5” by 1” steel bar transoms. Mul- P hoto courtesy The Winter Garden is framed with lions are spaced at 6’ on center, while structural steel and clad entirely with the transoms are aligned with the fourth, glass, soaring 83’ at its apex. The gar- fifth, and sixth levels of the base build- ’s roof is supported by four main ing. The wall framing was fabricated as Feinkopf Ph columns. Each column comprises eight a series of “ladders,” with two adjacent 9”-diameter steel pipes with 1-5/8” walls mullions and the transoms between o tography. clustered together to create a single them shop welded into a single assem- column with an overall outside diameter bly. As each “ladder” was erected in of 33”. The column bases are located the field, the transoms between each

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

$10M OR GREATER, BUT LESS THAN $25M NATIONAL WINNER . The University of Arizona tephen Criswell S

y Large Binocular Telescope Enclosure b Mount Graham, AZ Photo

JUROR COMMENT “A precision structure, with very tight tolerances, designed for unusual loads—movement of the structure due to environmental loads, rotation of the telescope, and thermal loads—not usually significant for structural designs.”

he University of Arizona’s The enclosure structure is co-rotat- Large Binocular Telescope ing—it rotates with the telescope, Structural Engineer and Architect (LBT), located on Mount Gra- although by separate drives. To maintain M3 Engineering & Technology Corpo- ham in southeastern Arizona, accuracy of observation, the telescope ration, Tucson, AZ houses an optical telescope in structure must be independent from Engineering Software theT equivalent of a 12-story building that the building structure. The main rotat- COSMOS/M rotates on a 38’-high circular concrete ing structure is a rectangular prism, 105’ wall foundation. Tolerances for design by 95’ by 115’ high. The available site, Owner and construction varied from as coarse cleared within Coronado National Forest, LBT Corporation, Tucson, AZ as 1/16” to as fine as nanometers for the was limited by permit. The building foot- Detailer, Fabricator, and Erector optics. print needed to be minimized, resulting Schuff Steel Company, Phoenix, AZ, In addition to the basic loading crite- in urban-type construction. AISC member ria, several operational elements were With an overall building height of 168’ incorporated into the design of the rotat- above grade, the rectangular prism struc- Detailing Software ing enclosure including: bi-parting build- ture has a system of steel beams and col- AutoCAD ing walls and roof to allow observation, umns with braced frames to carry loads General Contractor a 55-ton overhead bridge crane, side down to a three-dimensional steel truss Hart Construction Management Ser- and rear ventilation , a roof snow- system supported by four bogie drive vices (HCMS), Safford, AZ melting system, a service , and assemblies. Some fabrication weighed access platforms for shutters, the eleva- as much as eight tons, while the load tor, and a weather station. transmitted to the support bogies was

May 2005 • Modern Steel Construction Photo by John Hill. approximately 2,000 tons. The bogies — Overhead crane: 55-ton capacity has several tight curves, limiting the rotate this mass at up to 2º per second — Seismic: UBC Zone 2B maximum length of a piece to 40’. to maintain alignment with the telescope. Steel framing forms a box with the All bolted connections were speci- Bogie assemblies are mounted on a cir- observing level at the bottom, two fixed fied as slip critical due to the dynamic cular steel track 38’ above grade. walls on the sides that carry the overhead nature of loads on the structure. Stress Displacement control of the struc- crane runway, and a fixed wall behind reversals are common during operations. ture for operating wind load cases was the telescope that houses the elevator. Due to the geometry of the structure, the accomplished by optimal use of diago- The two sidewalls and a back wall incor- sidewalls that support the crane rails nal stiffening of the structure. Survival porate horizontal rolling ventilation doors. will move laterally when the shutters are wind load displacements are controlled Two 33’-wide moveable shutters, one for opened and closed. Also, lateral deflec- by latch mechanisms designed to tie the each of the telescope’s 8.4 m primary tions due to wind will affect the operation moving parts of the structure together to mirrors, are “L” shaped. The vertical 93’- of the crane as the crane rail supports accomplish lateral stiffening and reduce high leg of each shutter forms the wall in move in and out. displacements to acceptable levels. front of the telescope and the 100’-long In order to control the deflections The rotating enclosure structure con- horizontal leg forms the roof of the box. within operational limits for door seals sists of eight levels, including a bogie Open configuration lattice columns and crane operation, an exterior struc- level, a mechanical , an and bracing with thicknesses less than tural skeleton was provided to both observation level, a visitors’ gallery level, 3/4” were used to minimize the thermal reduce the deflections due to shutter an elevator equipment room, a crane mass of the structure and to increase movement and wind loads. The unique access level, a meteorological level, and thermal response to air temperature configuration of the LBT enclosure com- a snow-melting roof. The design criteria changes. bined with the environmentally decreed were as follows: The fourth level is an tight site provided interesting challenges — Wind speed with telescope opera- interstitial space of the 16’-deep two-way to the structural steel design and erec- tional: 45 mph (shutters open) trusses consisting of steel wide-flange tion. Steel provided the flexibility and — Wind speed with shutters open: 90 chords diagonals and verticals. The light weight required for the unique func- mph (telescope not in operation) interstitial space houses the mechanical tions of the structure.  — Wind speed survival: 125 mph (shut- and electrical support systems for the ters closed) telescope. — Base elevation: 10,720’ above sea The LBT enclosure structural design level incorporated details to facilitate erection — Snow load: 90 psf on Mount Graham at 10,720’ elevation. — Ice load: 60 psf The access road up to Mount Graham

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

$10M OR GREATER, BUT LESS THAN $25M MERIT AWARD

St. Martin’s Episcopal Church Houston

Photo by Christof Spieler.

Structural Engineer Matrix Structural Engineers, Houston Engineering Software RISA-3D RAM Steel Owner St. Martin’s Episcopal Church, Houston Architect Jackson & Ryan Architects, Houston Erector Photo

Steel Masters, Inc., Houston, SEAA by Mark Scheyer member General Contractor Tellepsen Corporation, Houston .

or the new sanctuary of St. Mar- Each steel frame, 80’ wide at the base Between the frames are tall stained tin’s Episcopal Church, the design and 87’ tall at the peak, carries the wind glass . To meet deflection team worked hard to capture loads for a 16’ strip of the façade. The requirements, these had to be braced to the form and details of a Gothic main columns are W27×146. Below 32’, the W27 columns. A steel frame around cathedral. Beneath the struc- the main columns are connected with the —fabricated to exact dimen- ture,F however, the buttresses and pointed moment connections and angle braces sions so the windows would fit in with- arches are anything but traditional. to the beams and columns of the aisle. out blocking—is attached to steel tubes Gothic architecture was the owners’ Above 47’, the columns are joined to the welded to the sides of the columns. Sev- request. The design team’s job was to gabled roof truss, which is made up of a eral different distributions of wind were make it work with a $20 million budget wide-flange top chord and double angle evaluated to make sure the columns and a tight schedule. Work on design diagonals. Under wind loads, the main would not twist excessively under this development started in December 2000 columns bend in an “S” shape due to the load. and the building had to be completed fixity from the aisle frames and the roof The towers posed their own problems. exactly four years later. The challenge truss. No column base fixity was counted The steel structure extends to 108’, and was to replicate, in modern materials, the on for strength calculations. With allow- above this are 80’-tall pre-engineered forms of an architecture based on load- ance made for some fixity, lateral deflec- steeples. Four W14×176 columns form bearing masonry. tion under 110 mph winds is less than the corners of the tower. Above 47’, the Several structural systems were con- 1/300th of the height. columns are connected with double sidered for this unconventional building. As soon as the steel frames were angle X-braces and ring beams. Below A hybrid system of steel and concrete erected, it was obvious that these were that, the opening for the balcony was considered. But the final choice the “bones” of a Gothic church. The and a large stained glass window elimi- was what had been sketched in the first diagonal braces of the aisle frames form nate both east-west X-braces in the design team meeting: a series of steel the arches of the aisle , and the tower. A series of girts, sloping beams, frames forming the nave, spaced at beams above form a classic triforium, and diagonal braces concealed in the 16’ on center to match the architectural used here for ducts. tower buttresses transfer the wind loads module, and two X-braced steel struc- The underside of the roof truss forms the sideways and down to the ground. tures forming the towers. shape of the vaulted ceiling. Because the tower brick extends 128’

May 2005 • Modern Steel Construction up and steps back often, shelf angles spaced 8’ to 15’ vertically provide for brick support. A system of tubes wraps around the towers at every shelf angle, following the shape of every buttress, pier, and wall. These are supported on outriggers off the main tower columns or on buttress beams, and are designed to take both the vertical brick load and the horizontal wind loads. The remainder of the structural sys- tem is fairly conventional; roofs are metal on steel joists and floors are con- crete slab on metal deck on wide-flange beams. The roofs of the aisle and nave are framed with sloping steel bar joists spaced 5’-4” on center. Deep, long-span metal deck was considered early on to eliminate the bar joists, but discussions with the construction team revealed that joists would be useful for supporting the plaster ceiling, lights, and maintenance catwalks. Point loads were specified on the construction documents and the joists were designed to allow these loads to be placed at any point along the joist. The general contractor and key sub- contractors, including the steel fabrica- tor and erector, were brought in early in the design process. Matrix structural engineers worked directly with the steel detailer to answer questions rather than go through a formal RFI process, and shop drawings were submitted in mul- tiple packages to allow fabrication to begin as detailing continued. The result: The building was completed on sched- ule and in time to install the pipe organ before the first service, Easter 2004.  . by Christof Spieler Photo

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

$10M OR GREATER, BUT LESS THAN $25M MERIT AWARD

Photo courtesy KL&A, Inc. Robert Hoag Rawlings Public Library Pueblo, CO . P hoto by Timothy Hursley Antoine Predock Architect Antoine Predock . Graphic courtesy

ueblo’s new Robert Hoag Raw- to allow free movement due to rotations Structural Engineer and Detailer lings Public Library serves as a at the ends of the trusses and thermal KL&A, Inc., Golden, CO, meeting place, a gallery for art movement. NISD member and permanent displays, and The library’s most prominent structural a location for special events. steel feature is a wedge-shaped trellis. It Engineering Software PThe 109,000 sq. ft structure uses bold forms a point starting at the north side of AutoCAD architectural forms and the juxtaposition the building that descends at 4˚ for 368’, RISA-3D of architectural finishes—with conven- ending in a 45’-long cantilever that is only RAM Structural System tional composite steel framing in most 2’-9” deep at its spring point. The trellis Detailing Software areas—to create interest and drama on is made of built-up, wedge-shaped tube SDS/2 a budget. sections connected by channel sections The first structural challenge was an and diagonal flat plate braces. At the Owner overhead structure spanning approxi- north side of the building, the deep end Pueblo City-County Library District, mately 98’ and connecting two sides of of the wedge contains a gallery that can- Pueblo, CO the library on opposite sides of a street. tilevers 16’ beyond the face of the build- Architects This “” included two levels of ing. This was accomplished with a steel Antoine Predock Architect PC, library stacks and administration spaces, moment frame that allowed side windows Albuquerque, NM (design) as well as mechanical equipment behind in the gallery. Anderson Mason Dale Architects, tall, sloping parapets on the roof. The The main stair in the atrium can- Denver, CO (executive) plan geometry of the skyway was trap- tilevers 20’ from the slab edge support. ezoidal in shape, with a glass-clad tri- However, the landing at the end of the Fabricator angular hole through the middle, allow- cantilever—typically a stiff element that Zimkor LLC, Littleton, CO, ing light in and a view of traffic passing resolves the forces between the struc- AISC member below. Four one-story tall trusses are tural stair runs—is 22’ long. An HSS General Contractor located at the third floor level, with the 16×16 member was used to connect the H.W. Houston Construction Co., second floor level suspended below. stair runs. A splice was required in this Pueblo, CO Directed spherical bearings were used HSS member to make the stair compo-

May 2005 • Modern Steel Construction nents portable and constructible, but the architectural finishes did not allow for any plates or other protruding elements. A completely field bolted splice was devised that fit entirely within the shape of the HSS to meet these challenges. The 54’-tall atrium glass wall was achieved with minimal structural support by providing horizontal tube-steel girts at the floor levels, with slender sag rods supporting the girts from above. Perhaps as important as the building’s structural elements was the project deliv- ery approach, driven by the needs of the owner and contractor to meet a tight schedule. Structural engineering firm KL&A employed its own in- steel detailing staff, using the 3D steel-detail- ing/modeling package SDS/2. Detailers were able to start work on the 3D model during the construction documents phase, which in turn resulted in the issue of complete shop drawings shortly after the final issue of structural construction documents, and before the final architec- tural package was released. 

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

LESS THAN $10M NATIONAL WINNER .

Desert Bloom Porte Cochere Paul Turang Photography y Paul Turang

b Cabazon, CA Photo

ith large “petals” stretch- The structure had to be as thin, effi- JUROR COMMENT ing into the desert sky, cient, and light as possible, prompting a the Desert Bloom Porte single layer steel grid shell frame with a “Excellent execution through Cochere of the Morongo typical structural member depth of 10”. collaboration in a design/build Casino Resort and Spa The typical shell structure requires a sin- hasW become a recognizable landmark gle or double curved surface geometry process.” for the Cabazon, CA getaway. with rigid boundary restraints to resist in- The initial concept and geometry of plane or out-plane loads. All out-of-plane Structural Engineer the Desert Bloom structure was devel- service loads are transformed into in- ASI Advanced Structures Inc., oped by The Jerde Partnership as a plane forces within the shell structure with Marina del Ray, CA series of overlapping, truncated double- some flexural forces in the ribs. These curved surfaces, or petals, that originate forces are collected in the 18” nominal Engineering Software from a central node and spiral outward. diameter pipe edge member, which are SPACEGASS The use of computer modeling and eventually resisted by the boundary Detailing Software analysis between the architects and foundation and building column support AutoCAD structural engineers was integral to the structure. Mechanical Desktop successful completion of the project. In order to facilitate fabrication The architects’ original AutoCAD 3-D and erection, each of the four petals Owner structural model was used as a basis for was divided into a series of individual Morongo Band of Mission Indians, structural design and detailing. Under curved wedge shape segments (“lad- Banning, CA a design/build contract, structural engi- der” frames). The dimensional division Architects neers ASI Advanced Structures devel- of the petal was limited by the fabrica- The Jerde Partnership, Venice, CA oped and presented an innovative struc- tion facilities and transportation logistics (design) tural scheme comprised of four separate of each ladder. The ladders were fabri- Thalden-Boyd Architects, Tulsa, OK petals and a central light tower. Each cated using two rolled edge (MC10×8.4) (executive) petal rises 40’ and spans 120’ on aver- channels forming the main radial ribs of age. The surface area of the entire struc- the petal. HSS 4×4 struts laced the ribs General Contractor Perini Building Company, Inc., Phoenix ture covers approximately 27,000 sq. ft. together. The complexity of the geometry

May 2005 • Modern Steel Construction . Paul Turang Photography y Paul Turang b Photo meant that all of the HSS struts had to be in the structure. This was required to mitered at different angles, and in some stabilize the shell until the structure cases with a double-mitered cut. was tied together through the bolted The division of each of the petals into connections and to support the con- lightweight ladders made the process struction loads generated by the com- of fabrication, shipping, and installation plex geometrical shapes. The shoring relatively simple and straightforward. The remained in place until all of the petals ladders were bolted together in the field were fully assembled, and the com- with galvanized steel bolts. The 40’ sec- bined frames of all four petals were tions of rolled, curved pipe were spliced tied together. together in the field. The double curva- The central light tower stands 60’ tall. ture was achieved by twisting each suc- It was fabricated in two sections that cessive piece of a single rolled section. were bolted together in the field. Approx- A key factor in the erection strategy imately 350,000 lb of custom-fabricated involved setting up a detailed shor- steel, and more than 5,000 bolts, were ing plan for each of the four petals used for the $2.8 million project. 

Modern Steel Construction • May 2005 E NGINEERING A W A R D S O F E X C E L L E N C E

LESS THAN $10M MERIT AWARD

Davis Conference Center Layton, UT

Photo by Jacom Stephens.

he Davis Conference Cen- the project was to provide open clere- ter was designed to provide story windows within the concourse that Structural Engineer state-of-the-art convention and would be unobstructed by the presence ARW Engineers, Ogden, UT reception spaces to the com- of bracing. The main concourse roof dia- Engineering Software munities of northern Utah. The phragm is significantly higher than the RAM Steel 42,420T sq. ft conference center, built rest of the building. To provide lateral RISA-3D adjacent to an existing hotel, houses a stability without using bracing or moment grand with movable partitions frames in the concourse, steel slip collar Owner that can be used to divide the space connections were added to each con- Davis County Gov. Dept. of Economic into eight smaller areas. The facility also course column at the level of the adja- Development, Farmington, UT includes smaller meeting rooms and cent braced roof diaphragm. The slip Architect reception areas connected by a con- collars were designed to transfer lateral Gillies Stransky Brems Smith, Salt course that runs the length of the facility, shear forces directly from the concourse Lake City terminating at a steel and glass turret. columns to the braced portions of the The ballroom and meeting rooms building on either side. They were also General Contractor on either side of the concourse feature designed to slip to accommodate antici- Sahara, Inc., West Bountiful, UT conventional steel framing and chevron pated deflections in the adjacent roof braces. The concourse was framed sep- structure from snow or live loads. arately with 8” square tube columns sup- To prevent undesirable sound trans- porting a barrel-vaulted roof constructed fer through the slip collars, each column of rolled tubes. was wrapped with an adhesive-backed A large component of the vision for elastomeric material at the connection to

May 2005 • Modern Steel Construction P hoto deaden sound transmission. This method of lateral support eliminated the need for by Jacom Stephens any transverse bracing along the length of the concourse. Only minimal bracing was required in the longitudinal direction at the ends of the concourse where the . elevation difference between concourse and the adjacent roofs was the greatest. The architectural design called for two 70’-tall freestanding towers to be constructed at the main entry. The towers were clad in sandstone veneer and sup- port 15’-tall exposed aluminum frames. This presented an engineering challenge due to high seismic forces generated by the weight of the sandstone veneer and the high design wind loads required by city ordinance. To design a stable fram- ing system for the towers, three dimen- sional computer models were developed Graphic courtesy ARW Graphic courtesy Engineers and subjected to the design earthquake and wind forces. The results indicated that the towers could be efficiently con- structed using 5” square steel tube seg- ments with fillet-welded connections. Metal stud infill framing and plywood sheathing provided the backup to anchor the sandstone veneer.  .

Modern Steel Construction • May 2005