2013 2 IDEASawards

Innovative Design in Engineering and Architecture with Structural Steel

The design and construction industry recogniz- The judges considered each project’s use of structural es the importance of teamwork, coordination and collabora- steel from both an architectural and structural engineering tion in fostering successful construction projects today more perspective, with an emphasis on: than ever before. In support of this trend, AISC is proud to ➤ Creative solutions to the project’s program requirements; present the results of its annual IDEAS2 Awards competition. ➤ Applications of innovative design approaches in areas such This program is designed to recognize all team members as connections, gravity systems, lateral load resisting sys- responsible for excellence and innovation in a project’s use tems, fire protection and blast; of structural steel. ➤ The aesthetic and visual impact of the project, particularly Awards for each winning project were presented to the in the coordination of structural steel elements with other project team members involved in the design and construction materials; of the structural framing system, including the architect, struc- ➤ Innovative uses of architecturally exposed structural steel; tural engineer of record, general contractor, detailer, fabricator ➤ Advances in the use of structural steel, either technically or erector and owner. New buildings, as well as renovation, retro- in the architectural expression; fit or expansion projects, were eligible. The projects also had to ➤ The use of innovative design and construction meth- display, at a minimum, the following characteristics: ods such as 3D building models; interoperability; early ➤ A significant portion of the framing system must be wide- integration of specialty contractors such as steel fabri- flange or hollow structural steel sections; cators; alternative methods of project delivery; sustain- ➤ Projects must have been completed between January 1, ability considerations; or other productivity enhancers. 2010 and December 31, 2012; Both national and merit honors were awarded. The jury ➤ Projects must be located in North America; also selected one project for the Presidential Award of Excel- ➤ Previous AISC IDEAS2 award-winning projects were not lence in recognition of distinguished structural engineering. eligible.

2013 IDEAS2 Awards Jury

➤ Paul Dannels, FAIA, is a founding principal of sdi structures, institutional buildings, including the Children’s Hospital of Ann Arbor, Mich., where he develops innovative structural Philadelphia and NYU’s Vanderbilt Hall Law School with Kohn systems for buildings on behalf of numerous aspiring Pederson Fox. In her early years in New York, she specialized and accomplished architects. His designs have received in waterproofing repairs for existing buildings, a technical skill several awards and recognitions, including three AISC that has remained influential in all subsequent projects. From IDEAS2 awards. His completed projects include the 1989 to 2000 she worked on the United States Holocaust Broad Art Museum at Michigan State University, the Law Memorial Museum. Prior to Snøhetta, Anne worked with Commons at the University of Michigan and the Lamar Santiago Calatrava on the PATH Station for the WTC Corporate Headquarters in Hudsonville, Mich. Dannels is Transportation Hub. In addition, she serves on the Board of the 2013 President Elect of AIA Michigan and has served in cultureNOW, which has produced the downtownNOW MAP leadership roles with several nonprofits, including Habitat of art and cultural institutions for Lower Manhattan as well as for Humanity of Huron Valley and the Center for Faith and the Manhattan ARTNOW. She is currently working on apps Scholarship. He studied engineering and architecture at for cultural mapping across the U.S. and in Canada. the University of Michigan and worked as a construction engineer in northern Michigan before founding sdi ➤ Chris Olson is chief content director of BUILDINGS Media, structures with his business partner, Andy Greco, P.E. Cedar Rapids, Iowa, where he focuses on digital and print content for facilities professionals who operate commercial ➤ Anne Lewison, AIA, senior architect and senior design leader and public buildings. He has more than 22 years of with Snøhetta, New York, was initially drawn to the city to focus experience in the facilities management and nonresidential on social housing and pursued subsequent opportunities for architecture/engineering/construction industries. He

MODERN STEEL CONSTRUCTION may 2013 2 ➤ The 2013 AISC IDEAS Awards jury, from left: Chris Olson, Charles Porter, Mark Simonides, Brian Raff, Paul Dannels, Anne Lewison, Dave Olson and Jacob Schueller.

graduated with a B.A. and M.A. from the University of and the Chicago Architecture Foundation (CAF). As an Michigan and a Ph.D. from Northwestern University. adjunct professor at Northwestern University, he teaches a course in commercial real estate development for the ➤ Dave Olson’s career with AISC member fabricator Master of Project Management program. Olson Steel, San Leandro, Calif., began in 1970 as a project manager and estimator. He progressed to the ➤ Brian Raff is the marketing director for the National Steel position of COO in 1995 and in 2002 became president Bridge Alliance and is responsible for providing strategic and CEO as well as the sole owner leadership and executing the national of the company. His career has marketing program that builds market A panel of design and included founding and/or leading share for steel bridges. Raff worked as a construction industry professionals several corporations engaged judged the entries in three structural engineer before joining AISC in diverse businesses, including categories, according to their in 2005 as its certification manager of real estate and shipyards. During constructed values in U.S. dollars: business development. He received the last 15 years, Olson has ✓ Less than $15 million his Bachelor’s degree in architectural served as director and trustee ✓ $15 million to $75 million engineering from Penn State University of organizations including the ✓ Greater than $75 million and his MBA in entrepreneurship and Tahoe Maritime Museum, the economic business strategy from DePaul Tahoe Yacht Club Foundation, University. the Ironworkers International Apprentice Trust, the Western Steel Council, Orinda community fundraising ➤ Jacob Schueller, a senior in the civil engineering program committees and the San Leandro Vocational Education at Marquette University, has been interested in structural Committee. He holds a B.S. degree in business engineering since early childhood. Now specializing in administration from California Polytechnic University structures, one of his primary focuses at Marquette has in San Luis Obispo. been Engineers Without Borders. He has made three trips to Guatemala with the program, most recently to ➤ Charles C. Porter is principal and cofounder of construct a 270-ft suspension bridge. This past year, Development Management Associates, LLC, Chicago, a Schueller tried his hand in research for the first time by developer and property manager of regional retail and determining the classification, rot sensitivity and strength mixed-use centers. With more than 30 years of leadership characteristics of Guatemalan lumber with Marquette experience in real estate development and construction, professor Chris Foley and fellow classmate Tim Lewis. Porter has played a primary development role, working as an owner and on behalf of client owners, for several ➤ Mark Simonides joined Turner’s Chicago business properties, including the 900 N. Michigan Ave mixed-use unit in 1982, where he has served as project engineer, project, the Houston Galleria expansion and renovation, superintendent, project manager and project executive on the Tabor Center redevelopment in Denver and expansion several of Chicago’s premier projects. He currently serves as work at the Old Orchard Center in Skokie, Ill. He holds a vice president and operations manager for Turner’s Great Bachelor’s degree in architecture from the Illinois Institute Lakes Region. In this role, he oversees the operations for of Technology and is a member of the International Council the Illinois, Indiana, Michigan and Toronto offices and is of Shopping Centers (ICSC), the Council on Tall Buildings responsible for the oversight and management of the and Urban Habitat (CTBUH), the Urban Land Institute (ULI) region’s 300 professional personnel.

may 2013 MODERN STEEL CONSTRUCTION National Award—Greater than $75 Million NASCAR Hall of Fame, Charlotte, N.C.

“ Totally bewitching, it grabs hold of your senses long before you find the words to articulate what it has accomplished.” —Paul Dannels

he challenge of designing a Hall of Fame for NAS- are analogous to the blur of a car racing past the spectator CAR? Capturing the essential spirit of NASCAR at tremendous speed. Within the Great Hall, a signature el- T racing in architectural form. In exploring the pos- ement of a curved, banked ramp leads the visitor from the sibilities for expressing speed and spectacle, the archi- main floor to exhibit levels above. The ramp contains a dis- tect and structural engineer were drawn to the arena of play of race cars frozen in a moment from a race, capturing action, the racecourse, where fans and race teams come in another way the speed and spectacle that is the essence together each race week for the experience of race day. of the sport. Curving, sloped forms are evocative not only of the dy- The selection of material for the Ribbon was critical to namic and changing sinuous shape of the racetrack but realizing the design intent. The team drew on another as- also the perception of speed, which, of course, is at the pect of the world of NASCAR—its technology—and was heart of any race. inspired by the process of shaping raw sheet metal to form The expression of these forms could only have been the body of the race car. This fundamental element has achieved through the use of steel, both as cladding and underlain all NASCAR race cars since the beginning of the structure, encompassing several long-span and architectur- sport. From a design point of view, metal imparts a light ally exposed structural steel (AESS) elements and employ- and airy feeling to the architecture. As the cladding ma- ing innovative approaches to connections, detailing and the terial the stainless steel softly reflects light and accentu- interface of structural steel with stone, glass and steel as a ates the dynamic aspect of the Ribbon as its sculpted form finish material. changes around the building. The Hall of Fame consists of four basic elements: Technically, there are tremendous benefits to the use of ➤ A large glazed oval shape forming a Great Hall serves as steel. Its lightness as a cladding element allows structural the symbolic core of the Hall of Fame support to be minimized and makes it possible to achieve ➤ A rectangular volume houses visitor services, including the great span over the main entry. The lightweight sub- entry and exhibit space on upper floors panels are easily assembled into unique shapes following ➤ A Hall of Honor is situated as an iconic element within the computer-generated geometry, and the shingled applica- Great Hall tion of the finished stainless skin panels are a natural solu- ➤ A broadcast studio enlivens the Hall of Fame Plaza, the tion to the complex problem of installing a durable finish on sweeping forecourt that welcomes visitors a curvilinear, warped surface. Design explorations of speed and spectacle evolved The Ribbon takes the form of a mobius, a continuous into an architectural element, the Ribbon that envelops the closed surface with only one side, formed from a rectan- full-block building in a form that speaks to the imagery and gular strip by rotating one end 180° and joining it with the spirit of NASCAR. Beginning as a curved, sloping exterior other end. The Ribbon is constructed using 165 prefabricat- wall enclosing the building, the Ribbon twists in a free span ed sub-panels and more than 5,000 stainless steel skin pan- over the main entry to form a welcoming canopy. Long, thin els. At the twisting canopy over the main entry, the Ribbon incisions in the metal skin, which are animated by running free-spans 158 ft and weighs 157 tons, with a 4-ft-diameter, lights in colors that represent those of recent race winners, 1½-in.-thick internal support pipe with W-shape cantilevers

MODERN STEEL CONSTRUCTION may 2013 serving as its backbone. At the ends of the twisting free- packages to enable detailing and fabrication of portions of span, significant reactions result from the action of gravity, the project to proceed before the full design was complete. wind, snow, ice and temperature. At one end the Ribbon A 3D Tekla model was used in the steel detailing to identify is anchored to the braced frame at the perimeter of the and resolve potential conflicts in the field. These efforts and Great Hall. At the other it is anchored to a concrete shear effective team communication allowed the long scheduled wall through a large embedded plate with closely spaced public opening to occur on time. deformed bar anchors and shear studs. At the top half of Owner/Developer 3 the embed plate, four 1 ∕8-in. Dywidag post-tensioned re- City of Charlotte; NASCAR Hall of Fame, Charlotte, N.C. bars provide a clamping force between the embed plate and the concrete wall. Developing the underlying structure, Owner’s Representative coordinating it with the primary structure of the building NASCAR, Charlotte and resolving issues of deflection, thermal expansion and Architects construction tolerance were achieved through an intensive Pei Cobb Freed & Partners LLP, New York design and engineering process that used the latest in BIM Little Diversified Architectural Consulting, Charlotte technology. Close coordination among the architect, struc- Structural Engineer tural engineering team and design-build contractor of the Leslie E. Robertson Associates, RLLP, New York Ribbon was critical to success. The result is a unique iconic General Contractor form, emblematic of the sport it celebrates, and the defining BE&K Building Group, Charlotte, N.C. symbol of the facility. The structure’s significant spans were achieved with Design-Build Contractor for Ribbon structural steel trusses: Zahner, Kansas City, Mo. ➤ A set of trusses spanning 175 ft achieve a grand column- Steel Fabricator and Bender/Roller free ballroom SteelFab, Inc., Charlotte (AISC Member/AISC Certified ➤ A 100-ft-long, bi-level footbridge, supported by a pair Fabricator) of one-story-deep trusses, links the ballroom with the Steel Detailer existing Charlotte Convention Center Hutchins & Associates, Clemmons, N.C. (AISC Member) ➤ Two- and three-story-high trusses cantilever 30 ft over the broadcast studio. Steel Erector One of the most significant AESS elements in the proj- Williams Erection Company, Smyrna, Ga. (AISC Member/ AISC Advanced Certified Erector) ect is the Vierendeel frame supporting the glass façade of the Great Hall. The lateral-load-resisting system at this Photographs façade also functions as the braced frame that supports Paul Warchol Photography, Inc. the Ribbon. The structural bid set was issued six months before the 100% CD set. The steel tender was divided into multiple

may 2013 MODERN STEEL CONSTRUCTION Merit Award—Greater than $75 Million Barclays Center, Brooklyn, N.Y.

“ This is the kind of bold design that becomes an instant landmark.” —Chris Olson

MODERN STEEL CONSTRUCTION may 2013 he new 675,000-sq.-ft Barclays Cen- Flatbush trusses. Three planar trusses ter, home of the NBA’s Brooklyn Nets, frame out an inner “oculus” in the center Tseats 18,103 and will host more than of the canopy. Supplemental steel is 200 sporting and cultural events annually provided within the oculus and at the (seating capacity increases to 19,000 for perimeter to support the latticework concerts). It features 95 luxury suites, four façade. Additional supplemental steel party suites, two conference suites, four hangs below the truss structure to bars/lounges, four clubs, a restaurant and create the supplemental framework to several street-level retail stores. support the “pouch.” The structural The arena is in a tight urban setting engineer, Thornton Tomasetti, provided near a subway station and train terminal, Tekla models, connection samples and presenting unique challenges for the foun- full connection design, which allowed dation system. The building was designed the team to produce models quickly, with a pair of truck elevators feeding a be- store large quantities of information low-grade loading dock with a large truck and coordinate with the entire team. turntable to facilitate turning. Columns in Even from its initial design, the project this region were transferred using large constantly pushed the limits of BIM plate girders spanning over the dock. and educated staff about the use of The dominant feature of the arena is several different programs and ways the weathering steel lattice that wraps to link and automate processes. The the structure. Rows of steel panels en- complex geometry of the façade and velop the exterior, including an entrance the shortened schedule meant that the canopy that cantilevers 85 ft over the team needed to coordinate in a 3D plaza. The façade design, with 12,000 environment and provide the information pre-weathered steel panels, and the can- to the contractor in this format as well. opy were added a month after the GMP Thornton Tomasetti’s team consisted package was released and two months of staff members across multiple offic- before the first steel mill order was due, es and practice areas. Teams in Kansas requiring the team to develop the façade City and New York designed the roof design while keeping pace with the origi- and bowl and then these two compo- nal schedule. Nearly 1,000 tons of steel nents had to be integrated. Construc- were added to support the façade, which tion support services teams worked on also became a prominent design feature. the Tekla models, model delivery and Another major structural feature, connection design; erection engineer- the distinctive arched roof, spans more ing was performed in the Chicago of- than 380 ft and is supported by a pair fice. The firm maintained staff on-site of 350-ft tied arch trusses spanning the full-time to accommodate changes and long direction of the arena. The roof sys- oversee work, and weekly coordination tem geometry was further complicated meetings helped to identify issues ear- by the additional loads imposed by the ly on and develop solutions proactively. outer façade system. As such, the build- Owner/Developer ing lateral system and diaphragms were Forest City Ratner Companies, Brooklyn, designed to resist thrust forces from the N.Y. roof arches, which were minimized by use of the tension tie. Architects The primary load-carrying members AECOM, Kansas City, Mo. of the canopy are a pair of box trusses SHoP Architects, New York cantilevering 85 ft beyond the column Structural Engineer supports along the Atlantic Avenue face Thornton Tomasetti, New York to the north and the Flatbush Avenue face to the southwest. Each box truss General Contractor consists of a pair of planar trusses Hunt-Bovis joint venture, Indianapolis ranging from 8 ft to 12 ft deep and laced Steel Fabricator together with horizontal bracing. The Banker Steel Company, Lynchburg, Va. planar trusses have W14 chords turned (AISC Member/AISC Certified Fabricator) web-horizontal to maximize out-of-plane stiffness with W14 braces and verticals Steel Detailer shop welded to the chords. Field splices WSP Mountain Enterprises, Inc., between trusses consist of bolted flange Sharpsburg, Md. (AISC Member) plate connections. Another box truss Photographs spans at the leading edge of the canopy Bess Adler between the tips of the Atlantic and

may 2013 MODERN STEEL CONSTRUCTION Merit Award—Greater than $75 Million National Geospatial-Intelligence Agency, Springfield, Va.

ituated on the outskirts of the Capital Beltway To fill the central atrium and interior of the building with adjacent to the Accotink Creek stands the National light, the west end wall of the atrium was glazed with a curtain SGeospatial-Intelligence Agency’s (NGA) 2.4 million- wall system and the roof of the atrium was covered with a sq.-ft campus, known as New Campus East (NCE). The transparent fabric membrane. The west end atrium wall facility was not only designed to enhance the agency’s consists of a 135-ft-tall by 140-ft-wide curtain wall backed capabilities as one of the leading intelligence organizations by a round HSS steel space frame. AESS requirements were in the world, but also to achieve a unifying, cultural incorporated into the design, fabrication and erection of the transformation. This effort is expressed in the design of the space frame structure, which served several functions. In nine-story main office building. Composed of two curved addition to supporting the gravity loads of the curtain wall, 900-ft-long overlapping bars around a 500-ft-long central it supports atrium roof gravity and wind loads and meets all atrium and elliptical auditorium, the building’s overall form mandated ATFP criteria. It also acts as a pedestrian bridge is in the shape of a lens—a fitting metaphor for NGA, at several levels, providing access and circulation between which serves as the nation’s eyes, the primary source of the towers. geospatial intelligence for the purposes of U.S. national The atrium roof is more than 500 ft long, with an area security, defense and disaster relief. of 45,000 sq. ft, and consists of AESS arched HSS mem- This defining architectural expression was accomplished bers supporting an air-filled ethylene tetrafluoroethylene primarily due to the benefits of structural steel. Steel facili- (ETFE) fabric roof. Although it appears clear, the custom tated the large bay size needed for program flexibility of silkscreen pattern and air-filled ETFE system provide signifi- the typical office; reinforced the architectural concept and cant daylight while minimizing solar gain. Being extremely imagery expressed in the transparent atrium roof, west end lightweight minimized ATFP-related effects and aided in re- wall and exterior V-columns; and accommodated the con- straints of the highly complex technical Anti-Terrorism Force ducing the tube structure size and tonnage; 18-in. by 12-in. Protection (ATFP) criteria as well as a demanding schedule. built-up HSS was used for the arched roof members, which Managed by the U.S. Army Corps of Engineers – Balti- vary in span along the tapered atrium, with a maximum span more District, the project has its origins in the 2005 Base of 125 ft and a 75-ft rolled radius. The roof arches span be- Realignment and Closure Act (BRAC). RTKL Associates, tween the office towers and were designed as “springs” to Inc., and KlingStubbins formed a joint venture to provide accommodate independent movement of the two wings un- design services, including master planning and full archi- der lateral and thermal loads. tecture, engineering, interiors, site/civil, landscape and The two 900-ft wings are configured to focus on the cen- technology design. tral atrium. This dramatic space and the atrium’s light-filled At 2.2 million sq. ft, the nine-story main office build- amenities create a “Main Street” for the office building com- ing is the second largest single-occupancy building in the munity. Enhancing this effect are the west end atrium wall world (after the Pentagon) and the largest federal building and the atrium roof structure. in the world to achieve LEED Gold certification from the U.S. The unique exterior design of the main office building Green Building Council. was achieved as a coordinated partnership between the

MODERN STEEL CONSTRUCTION may 2013 Merit Award—Greater than $75 Million National Geospatial-Intelligence Agency, Springfield, Va.

“ The various bridges are an eye-catching aspect of the structure and add convenience and function to the vast space.” —Jacob Schueller

architect and structural engineer. Signature V-columns spaced at 40 ft on center are featured along the first- and second-floor perimeter, providing a separation between the visually solid base and the triangulated precast façade of the upper six floors, while also continuing the diagonals of the upper façade. In addition to providing a strong aesthetic statement, the V-columns participate in the lateral load resisting system and accommodate alternate load path/progressive collapse design. Removal of any V-column leads to loads above being shared between transfer girders at the fourth floor and roof levels. Owner/Developer National Geospatial-Intelligence Agency, Springfield, Va. Owner’s Representative U.S. Army Corps of Engineers – Baltimore District, Fort Belvoir, Va. Architect and Structural Engineer RTKL/KlingStubbins joint venture, Baltimore General Contractor Clark/Balfour Beatty joint venture, Bethesda, Md. Steel Fabricator and Detailer SteelFab, Inc., Charlotte, N.C. (AISC Member/AISC Certified Fabricator) Consultant Hinman Consulting Engineers, San Francisco Photographs James West, J West Productions Paul Warchol Photogaphy, Inc. David Whitcomb (RTKL)

may 2013 MODERN STEEL CONSTRUCTION National Award—$15 Million to $75 Million City Creek Center Retractable Roof, Salt Lake City, Utah

“Having a roof spanning two city blocks that can be transparent and open and close is amazing. —Charles” C. Porter

eginning in 2003, the Church of Jesus Christ of Latter- pairs of glass-covered, arching panels that cantilever 33 ft day Saints developed plans to transform two Salt Lake from the adjacent structures over the retail concourse. When BCity “mega-blocks” just south of the town’s Temple closed, all six panels seal together and create an air- and Square into a 5.5 million-sq.-ft, mixed-use development water-tight barrier. To open, the panels part in the middle and featuring retail, residential, office and parking space. The retract onto the building structure as the panels bow down out centerpiece would be a man-made replica of the area’s of sight from below. Key to the bowing action are innovative historically significant City Creek that would meander for whalebone-shaped ribs that support the glass roof. Each roof two blocks and be surrounded by walkways and a six-acre panel is comprised of three parallel whalebones made of public park. Developers wanted an urban, open-air setting curved and tapered welded steel box girders that run from but also needed the assurance that retail businesses would the tip of each panel’s arch to the end of its backspan. The be protected during inclement weather. After studying glazed portion of the three whalebone arches are joined by many skylight possibilities, structural engineer Magnusson four purlins made of 8-in. A106 Grade B pipe and one purlin Klemencic Associates (MKA) produced a retractable roof of HSS10¾×½-in. ASTM A500 Grade B tube. concept that would fully meet the developer’s needs. Uni- The purlins are designed with concealed connections Systems was selected as the design-build contractor, with that are invisible from below and provide attachment points MKA as their structural engineering sub-consultant, and for 6-ft, 4-in.-sq. panes of glass. A typical roof panel is Ducworks as the steel fabricator. The resulting retractable, glazed with 72 panes of glass, each weighing approximately barrel-vaulted roof is configured in two sections, each 300 lb, although the size of each panel varies because of the spanning one city block. roof’s curvature. The three whalebone backspans are con- Each section is 240 ft long and 58 ft wide, with an S- nected with rectangular HSS ASTM A500 Grade B tubing in shape that echoes the curve of the signature creek below. a K-brace configuration to provide shear stiffness between The precision-sculpted steel and glass transparently shields them. In order to meet special finish and detailing require- patrons when closed and disappears from sight when open, ments, the side and bottom whalebone girder walls were connecting nature with the areas below. ground and filled to produce perfectly flat plane surfaces, For each block, the retractable roof is comprised of three and a Tnemec Fluoronar paint system gives the whalebones MODERN STEEL CONSTRUCTION may 2013 and purlins a high-quality metallic finish. The whalebones 8 ft per minute and opens or closes in approximately six were built at Ducworks’ fabrication facility in two sections us- minutes. Each panel has a unique operating sequence to ing custom-designed fixtures and joined with a plate-weld- prevent the panels from interfering with one another as ed connection to accommodate the unique geometry. The the seals engage and disengage. Because the S-shaped pre-assembled rail girders and whalebones were hoisted curve of the roof causes the three panels on one side to onto the roof, and the panels were assembled in place. converge when opening, the center panel on that side Each 10½-ton whalebone is supported by a 27-in. dou- remains in the raised position when opening, rather than ble-flanged steel wheel located at the bottom of the arch bowing down, to prevent collisions. The roof’s curvature, and two guide rollers located at the end of the backspan. along with the complex seals and intersecting panels, The wheel follows one geometric path on top of the rail made the control system the most complicated ever de- girder, and the guide rollers ride an inclined track along the veloped by Uni-Systems. bottom of the rail girder. As the guide rollers travel up the Owner incline, the roof’s cantilevered front edge dips down, caus- City Creek Reserve, Salt Lake City ing the roof to bow down, with the wheel as the vertical rotation point. The guide roller track surface is a heat-treat- Architect ed, hardened plate welded to the A572 Grade 50 steel rail Hobbs + Black Architects, Ann Arbor, Mich. girder. A custom welding procedure was developed to join Structural Engineer the two elements to avoid damaging the hardened plate. Magnusson Klemencic Associates, Seattle The flanges on the center wheel closely surround the center rail and act as wheel guides. The flanges on the two outer General Contractor wheels leave a slight gap around the rails to accommodate Jacobsen Construction, Salt Lake City lateral movement between the three rails caused by con- Steel Fabricator struction tolerances and structural and thermal movement. Ducworks, Inc., Logan, Utah (AISC Member/AISC Certified Locking pins mounted to the whalebones automatically Fabricator) engage the rail girders when the panels reach the open or Steel Erector and Mechanization Consultant closed end of travel. With the pins engaged, the roof pan- Uni-Systems, Minneapolis (AISC Member) els can accommodate differential movement from potential seismic activity. Photographs An industrial computer located in a remote control Michael Dickter, Magnusson Klemencic Associates room operates the retractable roof, which travels up to Uni-Systems may 2013 MODERN STEEL CONSTRUCTION National Award—$15 Million to $75 Million HL23, New York, N.Y.

“ The expression of the diagonal steel bracing on the exterior is the icing on the cake.” —Charles C. Porter

ocated in Manhattan’s West Chelsea District at the high-strength steel rock anchors into the 3-ft raft founda- corner of 23rd Street and 10th Avenue, HL23 cre- tion at specific locations. L ates a new 14-story, 42,395-sq.-ft ultra-luxury resi- The building’s dual-lateral support system is the most dential building. In total, the project houses 11 condo- intriguing element of the structure. The SPSW system is lo- minium units, 3,585 sq. ft of ground-floor gallery space cated at the elevator and stairs in combination with a full- and an elevated terrace/garden area. The floor plate of building perimeter braced frame system. As a true sign of the building, which is smaller at the base than at the top, synergy between form and function, the architect incorpo- owes its uniqueness to the existing elevated exposed rated the perimeter lateral pipe braces into the final interior High Line—retrofitted into a city park facility (see “Ele- aesthetic of the residences. This required special care dur- vated Experience” in the 08/2009 “What’s Cool in Steel” ing the design of the exposed connections of the perim- section)—located at the eastern portion of the building eter steel diagonal braces to perimeter steel beams. It was lot. The primary steel structure is clad with a mega-panel achieved by replacing the traditional use of multiple-bolt glass and stainless steel curtain wall system. The mega- gusset plates with end plates hidden in the concrete metal panel system is located on the north, south and part of deck slab for intermediate diagonal braces and with pin-end the east façades, with the remainder of the east façade connections for end braces. clad with an all stainless steel system. Architectural requirements played a large part in the fi- The project’s distinct form comes from the dramatic slop- nal structural layout. The use of structural steel was driven ing of the south and east façades, creating a dynamic and by three primary factors: minimizing the overall weight of undulating 3D composition. As a result, many of the steel the structure for the capacity of the raft foundation, mini- beams have axial loads to hold back the outward sloping mizing the amount of interior columns and providing the steel columns to the main lateral resisting system in addition perimeter diagonal architectural expression. The SPSW to the bending moments due to gravity loads. As an added system provided the project with the benefits of increased level of redundancy, steel reinforcement bars were placed stiffness and smaller dimensions—both tremendous ben- inside the concrete slab above the metal deck at specific efits for this site. locations to hold the columns back to the steel plate shear In New York City, many residential buildings are de- walls (SPSWs). In some cases where it was difficult to achieve signed using a cast-in-place reinforced concrete flat direct load path, two V-shaped 1½-in. steel tension rods in- plate system. However, due to the unique geometry side 2-in. full-length PVC sleeves were used inside the con- of the building, the sprawling architectural layouts, the crete slab above the metal deck and anchored the outward quality of the soil and the hybrid gravity and lateral load sloping column to the SPSWs. system on the perimeter of the building, steel was the The building slopes east from bottom to top, creating more economical and efficient material of choice for a large, destabilizing cantilever over the High Line. This HL23. Floor beams are composite with the concrete leaning gravity cantilever was stabilized by tying down the slab-on-deck; however, all of the intermediate steel west side net tension columns into the foundation system beams were removed to increase headroom in the living and installing twelve 13∕8-in. double corrosion-protected areas. This was achieved by using shored construction in

MODERN STEEL CONSTRUCTION may 2013 many areas with a slab thickness between 6 in. and 7 in. and varying metal deck properties throughout the floor. At the upper floors, the maximum beam/ girder span was nearly 30 ft-0 in. Due to the building’s modest height, a SPSW sys- tem was considered both structurally effective and visually attractive. The east-west dimension of the building is very tight, and any reduction in dimen- sion of structure was beneficial to the floor layouts. Using 3∕8-in.-thick plates instead of wide-flange brace members freed up an extra foot of useable floor area between the columns for each wall of the system. This 2-ft savings was an enormous achieve- ment in a building that is 38 ft wide. In addition, the SPSW system adds a considerable amount of stiff- ness over a braced frame. The extra capacity was critical for this building with its gravity overturning characteristic; SPSW systems typically slow down the erection process compared to braced frame sys- tems. The team developed a system where the pe- rimeter of the plate was continuously welded, with three of the four sides shop welded. Prefabricated shear wall panels, with integral columns and beams, were shipped to the site and spliced in the field. This process ultimately saved a considerable amount for erecting the SPSW system. The second part of the dual lateral system is com- prised of perimeter braced frames on each of the el- evations. In addition to lateral loads, the perimeter Owner braced frames in many locations are part of the gravity 23 High Line, LLC, New York system as well. The braced exoskeleton members are Architect 8-in.-diameter extra-strong pipes at the north, south Neil M. Denari Architects, Los Angeles and part of the east façades; HSS10×5 on the west fa- çade; and 6×4 back-to-back angles on the remainder Structural Engineer of the east façade. All of the pipe elements are pri- DeSimone Consulting Engineers, New York mary architectural features and are exposed on the fa- General Contractor çade and in the residences; therefore, the detailing of T.G. Nickel and Associates, Ronkonkoma, N.Y. these elements was heavily scrutinized. In addition to standard AESS specifications, the nodes of the system Photographs have been designed with an exposed single 1½-in.- Rinze van Brug Photography diameter pin connection. The final building aesthetic DeSimone Consulting Engineers merges the strength and beauty of steel into a com- Neil M. Denari Architects posite whole.

may 2012 MODERN STEEL CONSTRUCTION Merit Award—$15 Million to $75 Million UC Berkeley California Memorial Stadium Press Box, Berkeley, CALIF.

“An overwhelming confluence of functional and structural challenges solved with the boldest single stroke possible— nothing timid about it. ”—Paul Dannels

MODERN STEEL CONSTRUCTION may 2013 uilt as a memorial to fallen alumni of World War I, the As the core wall system rocks in the event of an earthquake, University of California, Berkeley’s Memorial Stadium the large drift angle of the cores would cause large bending and Bhas endured as one of the most picturesque venues shear forces in the press box above. In order to alleviate these in college football from its opening in 1923 for the “Big forces and economize the design, the press box was supported Game” versus Stanford to the present day. After it was dis- on steel pins at the center of each core. These pins allow the covered that the stadium was at particular risk in the event of press box to pivot on the cores and minimize damage to the an earthquake, which is further exacerbated by the fact that steel structure. Each 7-in.-diameter high-strength steel pin is it sits above the Hayward Fault, the university undertook a sandwiched by five 100-ksi steel gusset plates. The entire press large project to seismically retrofit as well as modernize the box structure is supported on twelve of these high-strength pin stadium. As a part of this project, the western stadium bowl assemblies. was seismically retrofitted and modernized with new concrete The top-level cantilevered balcony is also a space truss seating bowl framing while keeping the existing historic pe- comprised of numerous small-diameter pipe sections. This rimeter concrete wall in place. balcony truss system, which includes seismic and out-of- The “crown jewel” of the project, however, is the new long- plane bracing, has several multi-member joint connections span two-story structural steel press box that floats atop the with some joints connecting up to eight pipe members. Due new west portion of the stadium. One of the main architec- to the complexity of these joints, coordination had to take tural design goals was to achieve a floating effect to the press place in a 3D platform (Revit and Tekla) between the fabrica- box by reducing the number of supports to a bare minimum. tors and design team. The resulting structure is 375 ft long with two 100-ft-long main Thanks to the complex nature of the site and surround- spans and end-span cantilevers of 33 ft. The press box arches ing neighborhood, there was limited space on-site to allow to follow the curvature of the existing exterior wall and is sup- for erection and construction of the press box. To address ported by four concrete cores (two at each end) and four cen- this issue, fabricator Herrick and general contractor Web- ter structural steel columns. The press box is two stories, with cor Builders enlisted the help of one of the largest crawler the first floor housing print, radio and TV media functions and cranes in the country (a 750-ton Liebherr crawler crane with the second floor housing a club space with views and seat- a 276-ft boom and 65-ft counterweight extension) to erect ing facing the field, as well as a dramatic 25-ft cantilevered the main press box truss in five large segments. The main balcony with a glass deck that faces the campus and provides space truss of the press box was assembled and welded panoramic views of San Francisco Bay and the Golden Gate on the playing field, adjacent to the seating bowl. Care- Bridge. The areas of the levels are 10,200 sq. ft and 12,500 sq. fully selected splice locations were determined to ensure ft, respectively. The main structure of the press box consists each of the five truss segments would be within the crane’s of a story-deep space truss that is comprised of radial trusses capacity for weight and reach. Each of the five segments that are supported by primary trusses that span between the exceeded 75% of the crane’s capacity and therefore were concrete cores and center columns. The occupant load for the considered critical picks. The largest pick of the five seg- entire press box is approximately 1,700 people, and more than ments was 165 tons at a 160-ft reach, which took the crane 1,350 tons of structural steel were used in its construction. The to over 95% of its capacity. overall construction cost for the project was $215 million, with The stadium reopened on time for the 2012 football season. the press box portion being $40 million. Owner Due to the stadium’s location above the active Hayward The University of California, Berkeley, Calif. Fault, the design of the press box and supporting concrete cores used several design innovations to allow for increased Architects seismic performance. The concrete cores that support HNTB Architecture, Inc., Los Angeles the press box provide the main vertical access to it. These STUDIOS Architecture, San Francisco tall, slender support elements, with the lumped press box Structural Engineer mass at the top, create a dynamic incompatibility with the Forell/Elsesser Engineers, Inc., San Francisco surrounding bowl structure. If this incompatibility had not been properly addressed, a major seismic event could General Contractor potentially cause substantial damage to the concrete cores Webcor Builders, San Francisco directly below the support points for the press box. To Consultant avoid this scenario, the cores and press box structure were Hassett Engineering, Inc., Castro Valley, Calif. seismically separated from the surrounding bowl and allowed Steel Fabricator and Erector to move completely independent of the main bowl structure. The Herrick Corporation, Stockton, Calif. (AISC Member/ The concrete cores were designed to rock at their bases to AISC Certified Fabricator and Erector) alleviate the seismic demand on the cores, which were also vertically post-tensioned to provide stability and a restoring Steel Detailer force when rocking. Fluid viscous dampers (shock absorbers) SNC, Compton, Calif. (AISC Member) that link to the cores were added within the bowl structure, Photographs providing a mechanism to dissipate seismic energy and to Tim Griffith control movements and accelerations in the press box. Sixteen dampers were used in the design of the stadium, each with 220-ton axial force capacity.

may 2013 MODERN STEEL CONSTRUCTION ee Hall III is a 55,000-sq.-ft addition to Clemson University’s College of Archi- Ltecture, Arts and Humanities in Clem- son, S.C. The building houses academic programs in architecture, art and planning, faculty offices and student workspace. Merit Award—$15 Million to $75 Million Conceived as “a building that teaches,” Lee Hall III—Clemson University, Clemson, S.C. Lee Hall III encourages informal learning through observation of its energy efficient design and exposed functional and struc- tural systems. The building was awarded LEED Gold certification by the U.S. Green Building Council and won an American In- stitute of Architects’ 2013 National Honor Award. Nearly all of the structural steel components in Lee Hall III are the direct manifestation of the architectural expression. The building is an open, double-height space (35 ft tall) housing a secondary internal structure of mezzanines and bridges. The structure’s roof is comprised of a lightweight composite concrete deck structure supported by exposed W14 steel beams. The roof rises 4 ft in a gentle arc to drain a planted green roof, which is punctuated by 25 7-ft- diameter skylights directly above the “column trees.” These assemblies consciously draw attention to the structural steel; they are comprised of 10¾-in.-diameter seamless steel pipes with 1-in.-thick walls and four curving “arms” built out of flat 1¼-in.-thick and 1-in.-thick steel plate. The unusually thick-walled pipe columns (ASTM A106 pipe typically used in oil and gas construction) allow remarkably slender columns and enhance their dramatic elegance. The four arms at the top of each column tree support lines of continuous W14 steel beams and allow the roof directly above each column to open into a skylight. The north and south façades of Lee Hall III are comprised of a custom in- sulated low-iron glazing, which spans floor to roof. The engineer worked closely with the architects to detail the support system for the glazing out of “ This elegant project shows a W6 structural steel members spanning up to 33 ft. The W6 window wall steel determined drive to reduce columns incorporates exposed C6 and WT3 ex- posed steel framing to support oper- to their most elongated and slender— able windows and doors. By directly supporting the glazing on structural a refreshing reminder to continue steel members (in lieu of conventional aluminum extrusions), the designers developed window walls of exception- to stretch design at every opportunity.” al slenderness with minimal and el- —Anne Lewison egant detailing that is consistent with the aesthetic of the primary structural steel frame.

MODERN STEEL CONSTRUCTION may 2013 The lateral systems for Lee Hall III consist of exposed connections and fabrication techniques that could be “X”-braced pre-tensioned cables on the north and south built by any steel fabricator without undo expense. All façades and back-to-back WT ordinary braced frames in the connections were fully detailed in the structural drawings east and west walls. The WT bracing is hidden in the east so that the alignment, appearance and architectural and west brick walls, but the cable X-bracing is a prominent character could be evaluated and refined prior to the architectural feature. The cable connections were detailed shop-drawing phase, thereby eliminating the fabricator’s to be exposed to view just above the finish floor and are connection engineering time and costs. Although the offset to pass one another just behind the W6 window wall structure features a curving, warped roof, no curved steel. steel was used in the building’s frame; the geometry is Beyond the window walls on the north and south a series of simple faceted arcs that nearly match a true faces of the building, a row of super-slender “Y”-columns curve. Variation in arc radii requires the metal deck to supports a steel trellis of exterior exposed W6 steel beams warp slightly as it spans. The structural drawings clearly and perforated metal panels. The exterior Y-columns are and simply convey the geometry in simple 2D plans, reminiscent of the 25 interior column trees but are flattened elevations and details without the need for 3D modeling into a two-dimensional plane. Each Y-column is fabricated or the use of digital files. from 4.5-in.-diameter HSS steel tubes and is up to 35 ft Each of the 25 column trees has its own unique geometry tall. Although the geometry of each Y-column is different, due to the changing curvature of the roof, but all column tree the castings connecting the vertical base of the Y to the arms were fabricated entirely out of flat plate, the geometry of branching arms are identical; repetition of the same casting which was determined from simple geometric rules. The realiza- geometry made the connections cost-feasible. tion of complex, organically inspired free-form shapes from the At the north and south ends of the east and west walls, careful assemblage of flat plate and straight pipe was key to the brick walls hover beyond the building enclosure in an 18- project’s success. ft double cantilever with no lateral support bracing. These Further cost reduction was achieved by responding to the cantilevered brick “wing walls” shade the ends of the north fabricator’s concerns regarding the blanket designation of and south window walls in a subtle but dramatic extension AESS. Rather than simply applying this requirement to all of the of the brick surface. The cantilevering steel structure resists exposed steel, the architects and the engineer identified only vertical brick loads and lateral wind and seismic loads, not those aspects of AESS that were critical to the project’s success unlike an airplane wing. and defined exposed painted structural steel requirements spe- A two-story level of mezzanines and connecting bridges cific to the job. comprises a nearly independent structure within the main Owner Lee Hall III structure. The shafts of some column trees pass Clemson University, Clemson, S.C. through holes in the mezzanine deck and do not support the framing, emphasizing the independence of the two struc- Architect tures. The mezzanine level is supported by W10 and W16 Thomas Phifer and Partners, New York steel beams and HSS5×5 square tube columns. Its structural Structural Engineer steel columns and beams were precisely coordinated and Skidmore, Owings & Merrill LLP, Chicago offset to align with architectural glass, wood and concrete surfaces. General Contractor Nearly all of the structural steel in Lee Hall III functions Holder Construction Company, Atlanta as both a load-carrying functional system and a sculpturally Steel Fabricator expressive medium. What is arguably most remarkable Steel LLC, Atlanta (AISC Member) about its use of structural steel is that the highly and Steel Erector expressive character was achieved without any expensive Williams Erection Company, Smyrna, Ga. (AISC Member/ or unconventional fabrication techniques, special AISC Advanced Certified Erector) finishes, exotic connections or the higher-tolerance AESS designation typical of this type of construction. Instead, Photographs the team worked closely to refine conventional, simple Scott Frances Photography

may 2013 MODERN STEEL CONSTRUCTION National Award—Less than $15 Million El Dorado Conference Center, El Dorado, Ark.

uccessful architecture tells the unique story of a with a wood shed that recalls the long timber mills of specific place, combining history with future aspi- this forested region. The repeating structural rhythm and S rations to create a timeless quality. vertical thrust of the naturally lit space is a subtle nod The El Dorado Conference Center (EDCC) tells the story to El Dorado native son architect Fay Jones; the spirit is of El Dorado, Ark., home to the world’s eighth-largest oil there without attempting to replicate the master’s work. company, which was created with the discovery of oil in Steel plates and channels are carefully layered to cre- southern Arkansas near the beginning of the 20th century. ate memorable elements in a collegiate gothic manner. With oil came the timber industry to pine country, propelling Wood is inlayed in bracing channels as stiffeners, creat- El Dorado into the South’s original “boom town.” ing an elegant yet simple expression of function. As oil in Arkansas was exhausted and related industries The EDCC’s large masonry wall planes act to hon- branched out globally, a city that reached 40,000 people had or the adjacent college campus’ legacy without the shrunk to 19,000 in recent years. Murphy Oil implemented a adorned 1900’s detailing. The true story of industry stunning proposal, the “El Dorado Promise,” guaranteeing bleeds through the masonry openings, expressed in every high school graduate with good grades a free college thoroughly modern cantilevered steel and glass bay scholarship. The new influx of families due of the promise windows and monumental stair landings overlooking the created the need to attract industry and a climate for re- town’s activity. A great brick arch that spans the entire newed civic pride—a new Boom Town. The community im- café/bookstore sits adjacent to the actual steel struc- plemented a series of public projects to increase exposure, ture, like a masonry ruin held in place by the preeminent including the El Dorado Conference Center, which is half construction method of today—a steel structure. The public meeting space, half college student services center. space opens to a new lawn for student and public use Drawing from its greatest industries of past and present to that is aligned with the heart of the campus. The site is the educational advancements of tomorrow, the EDCC cre- master planned for a future amphitheater with the goal ates a memorable architecture intended to help propel El of creating an arts district to further extend the feel and Dorado into a regional meeting destination. activity of downtown to the college. The unique nature of community ownership—public, A large steel bridge arch that runs the length of the business and education—demanded an architecture that Public Hall supports the suspended auto court canopy, would blend the three seamlessly together, creating a reflecting the steel arched roof of the campus gymnasium place for all to interact and learn. With three constitu- (an old armory) across the street. What appear to ent groups came different desires for architectural style; be limestone columns like those of the town square’s all agreed, however, that the building should exude a courthouse are actually sun control fins, stopped short timeless quality. Instead of relying on the cliché of past of the roof to honestly express the lighter steel structure historic building styles, the design focuses on the rich beyond, which allows the roof to float above. Where story of place and the industry that put El Dorado on wood beams are used, they are still clearly supported by the map. Located between a historic, thriving downtown the steel structure. The unique design of the large multi- square and South Arkansas Community College, the site purpose room, Murphy Hall, allows an indoor/outdoor links “town to gown,” connecting the two great sources north stage for public events, such as the yearly music of public pride. The square and college also influenced festival. The room is purposely on axis with the landmark the building of two naturally lit public halls, one on the dome of the First Baptist Church to the north, which is path to downtown, the other to the College Academic visible from the space. The room can be lit 100% naturally, Quad. These interior streets work like the town square, a rare feature in meeting facilities and a key sustainable lined with a café, bookstore and public/college meeting strategy for the facility as a whole. Clerestory windows rooms, while serving as galleries for the college and art are protected by extended top cords of trusses capped center. The great halls’ intersection serves as the living with galvanized steel grates, used as sun control shades. room of the community as well as “college central” for The park-like setting along Southwest Avenue chan- student services. nels students to appropriate street crossing points while The key component of a design philosophy of cel- creating a beautiful entrance to downtown and the cam- ebrating industry is the honest expression of the steel pus. One of the project’s most important steel elements structure and the craft of its detailing as opposed to sits as a focal point of the main lawn as a reminder of the the typical applied ornamentation. Every steel column, events of 9/11. A piece of the World Trade Center steel beam, bolt, and connection is exposed in the same func- is an integral part of the Arkansas 9/11 memorial, which tional fashion as would be seen on oil derricks and the honors four Arkansans lost. The portal structure is built steel bracing and platforms that adorned them. Student with existing granite slabs salvaged from a local natural lounges float on upper-level platforms, with catwalk-like gas industry drilling process. bridges connecting departments; students can see and The El Dorado Conference Center weaves time, place be seen sitting above the public paths. The main public and story together, closing a gaping hole in the urban fabric hall is a repeating cross section of a derrick’s shape and between town and college while serving as a beacon for the bracing, creating a soaring cathedral-like space, capped renewal of Arkansas’ original boom town.

MODERN STEEL CONSTRUCTION may 2013 “Beautifully blended design using wood inlays in structural steel members.” —Mark Simonides

Owner/Developer El Dorado Economic Development Board, El Dorado, Ark. Architect Polk Stanley Wilcox Architects, Little Rock, Ark. Structural Engineer TME, Inc., Little Rock, Ark. General Contractor CDI Contractors, Little Rock, Ark. Photographs Timothy Hursley

may 2013 MODERN STEEL CONSTRUCTION “ Rarely does low-income housing push the limits of architecture or structural engineering, yet this one did.” —Jacob Schueller

Merit Award—Less than $15 Million Sierra Bonita Mixed-Use Affordable Housing, West Hollywood, Calif.

MODERN STEEL CONSTRUCTION may 2013 ierra Bonita is a 50,000-sq.-ft, plate design, Sierra Bonita successfully five-story, mixed-use, afford- integrates affordability, sustainability Sable housing structure located and style. This integration is most in West Hollywood, Calif. Commis- apparent in some of the building’s sioned by the non-profit West Hol- visually striking elements such as the lywood Community Housing Cor- courtyard’s eccentric pink fiberglass poration (WHCHC), the building is wall. the pilot project for the city’s Green The wall at the entrance of the Building Ordinance—a local alterna- courtyard resembles a series of tive to LEED and one of the first pro- intersecting shards and is in fact grams of its kind in the nation. based off of the eccentrically braced There is parking at the basement steel frame. This frame forms a and ground-floor levels, and the component of the lateral resistance ground floor also provides space for system in the north-south direction. WHCHC and other non-profit groups It uses a variety of wide-flange beams such as AIDS Project Los Angeles. The and tube steel bracing to adequately building’s 42 one-bedroom apartments express the randomness desired for are set aside for low-income residents the architecture. with special needs, including the In addition to the eccentrically braced elderly, disabled and those diagnosed frame, for north-south stability a concen- with HIV/AIDS. trically braced frame runs along the east The perimeter columns of this 112-ft façade, while two segments of a concen- by 100-ft building are spaced at 20 ft. trically braced frame run along the west To allow for its various uses, the building façade. The concentrically braced frames was designed with only four interior col- are comprised of W16 beams, W12 col- umns from the ground floor up. At the umns and HSS braces ranging in size courtyard, floor beams connect to 60-ft- from 6×6 to 12×8. long girders, which carry the forces back For east-west stability, moment to columns at the corners. frames along the north and south faces of Zoning restrictions limited the build- the building utilize W18 girders spanning ing height to a maximum of 50 ft. Typi- 20 ft to the strong axis of W14 columns. cal apartment floor slabs are 1½-in. Canopies, framed with HSS, at the metal deck with 4½-in. normal weight roof cantilever out and down past the concrete slabs which span 20 ft and north façade to support photovol- work compositely with the W24 steel taic panels, which provide energy for beams. These beams are cambered the building. Recycled steel is used and span 43 ft, from the courtyard to throughout the project, and steel fram- the perimeter walls, and the slab has ing with long-span deck is used to ac- extra reinforcing to allow the steel commodate the parking grid below beams to align with partitions between and to minimize floor-to-floor heights. units, resulting in apartments with Owner higher ceilings. The deck was shored West Hollywood Community Housing to control deflections under the wet Corporation, West Hollywood, Calif. weight of the concrete. The roof fram- ing is lighter as the deck supports no Architect concrete, minimizing seismic loads and Tighe Architecture, Santa Monica, material use. Calif. The ground- and second-floor slabs Structural Engineer are more traditional 3-in. metal deck Gilsanz Murray Steficek, New York with 3½-in. normal weight concrete slabs spanning up to 11 ft to compos- General Contractor ite beams and girders. The second Parker/Sarg Industries, Pasadena, Calif. floor supports an outdoor bamboo Consultant garden and apartments while the Castle and Gray International, Inc., ground level includes offices, retail Malibu, Calif. spaces and parking. Photographs In a sector that is accustomed to Art Gray Photography cutting corners and settling for boiler-

may 2013 MODERN STEEL CONSTRUCTION “It’s a product that could go into immediate production and be used everywhere to the benefit of many.” —Anne Lewison

Merit Award—Less than $15 Million Solar Canopy, Chicago, ILL.

he Solar Canopy is an 11-ft-tall prototype structure team aimed to create a flexible design that could accommodate consisting of 3 tons of AESS and is designed to har- a single structure or multiple structures linked back-to-back, Tvest solar energy for use in powering electric/hybrid creating a shaded corridor for users in the interstitial space. vehicles. Conceived by Carbon Day Automotive to pro- In large-scale applications of the Solar Canopy, parking lots mote sustainability initiatives in Chicago, the structure was can be converted into giant plug-in charging stations, with unveiled in a temporary location in Douglas Park as one the possibility of surplus energy being donated to the power of the focal points of the International Olympic Commit- grid. Bolstering its sustainable appeal, the structure has the tee’s visit to the city. Owned by the Chicago Park District, potential to collect, store, filter and reuse rainwater to irrigate the Solar Canopy found its permanent home on Northerly adjacent agricultural or park lands. Island in 2010 and has been actively charging electric ve- As the structural engineer of record and steel detailer, Thorn- hicles ever since. ton Tomasetti designed all of the Solar Canopy’s components With a construction cost of $67,000, the structure employs and connections, providing a cost-efficient structural design a cost-efficient, aesthetically pleasing and sustainable design without compromising the architectural aesthetics. To achieve that was achieved through integrated structural solutions, this solution, the smallest diameter pipes possible were bent streamlined fabrication and simplified coordination. with compound curves. The slender pipes were visually pre- Designed by Adrian Smith + Gordon Gill Architecture, the ferred both for a graceful appearance and to limit encroachment Solar Canopy seamlessly blends into the background of any on parking spaces. The firm used 3D CAD and 3D analysis to park and artistically complements a neighboring building. design the complex curves that give the structure its tree-like The elegant design includes a tree-like steel superstructure form. Since an integrated conduit is required to transfer energy that can support up to 900 lbs. of solar equipment, a 300-sq.- from the photovoltaic panels to an underground battery pack, ft canopy featuring photovoltaic panels and a subterranean small access holes were provided at the top and bottom of the concrete foundation anchoring the structure to the ground. pipes to conceal the electrical wiring as well as to drain water. The prototype design is adaptable to integrate a range of Bolted connections were minimized in favor of welds to photovoltaic technologies at varying orientations, providing achieve the architectural design intent. Because of the in- sustainable solutions to any location around the world. The creased use of welds, the team sought to decrease field work

MODERN STEEL CONSTRUCTION may 2013 by performing as much of the fabrication in the steel shop as of the Solar Canopy while still achieving a cost-sensitive, func- possible. This process helped to reduce costs and allowed tional structure. With only three face-to-face meetings, the ma- for better quality control of the end product. The canopy was jority of communication was accomplished electronically. Team shop fabricated as seven pieces that were limited in size to fit members shared ideas and designs effectively through virtual on a standard truck bed, streamlining shipping. Once on-site, communication methods, creating an efficient design process. the base was set and the columns erected. The roof structure From concept to working prototype, the Solar Canopy design was delivered as two pieces and connected on the ground. was completed in 25 days. As a prototype structure, the Solar The solar array was then installed and the roof lifted into posi- Canopy is not only versatile with its ability to integrate multiple tion and set on the bolted seat connections found at the tops applications at a variety of sites, but is also unique in its striking of the columns, and the connections were designed so that yet simplistic appearance. the roof structure concealed the bolts from view. Owner Located on Chicago’s lakefront, the Solar Canopy’s design Chicago Park District, Chicago accommodates the wind and snow loads of the city’s infamous weather while providing an imaginative addition to the land- Architect scape. Creating the appearance of sprouting from the ground, Adrian Smith + Gordon Gill Architecture, LLP, Chicago the canopy is anchored to a concrete foundation located 1 ft, 4 Structural Engineer in. below grade. The base connection and foundation were de- Thornton Tomasetti, Inc., Chicago signed to resist a significant permanent overturning moment created by the unbalanced sprouting columns that asymmetri- General Contractor cally cantilever from the base. To diminish deterioration of the Carbon Day Automotive, Chicago structure, the concealed foundation allows for the heaviest of Steel Bender-Roller parking lot wearing surfaces, and hot-dip galvanized steel pre- Chicago Metal Rolled Products (AISC Member), Chicago vents corrosion to the components exposed to the elements. Photographs Extensive collaboration was necessary among a team con- Steinkamp Photography sisting of nine firms to realize the unique architectural design

may 2013 MODERN STEEL CONSTRUCTION issoula architect Eric Hefty grew up in the logging cen- Mter of western Montana, and one of his first summer jobs was mak- ing glulam beams and drafting shop drawings for the beams and stress skin plywood panels at a local mill. With this hands-on experience with systems and materials, he grew to appreciate steel as a complete material and one that can be used for both structure and finish. Adding to Hefty’s appreciation of steel was a visit he made years ago to Bannack, a celebrated Montana ghost Merit Award—Less than $15 Million town, where he saw a steel-clad side The Corner Condominiums, Missoula, Mont. wall on a building, which had weathered to a beautiful rusty patina. This was in contrast to the monochrome grey color of the rest of the community; when originally built, it is doubtful that this light-gauge, rusty façade would have been the goal of the builders. But it was very much Hefty’s goal for the Corner Condominiums, a zero-lot- line urban infill project he designed for a triangular site near downtown Missoula. It is a fitting capstone at the end of the linear commercial area known as the “Hip Strip.” Because of the constraints of the site, bordered by two main arterials, and a program that required every inch of allowable height, the team did not even consider any structural sys- tem other than steel. Some additional factors that contributed to this obvi- ous choice were: ➤ A complex triangular building shape ➤ Having longer spans and restrictive column spacing for the underground parking and juxtaposing a triangular building on top of a rectangular parking grid ➤ Multiple staggered floors and changes in floor elevation going from three levels to five and back to three levels ➤ Using very basic erection equipment and not being allowed to encroach on the two adjacent arterials. (This was simplified with accurate steel fabrication and mostly bolted steel connections.) The steel structure was built “around” a wheeled crane, which eliminated traffic disruption ➤ The extensive glazing of the exterior walls combined with the

MODERN STEEL CONSTRUCTION may 2013 narrow building profile required the A visually stunning use of three moment frames and four “ rigid frames palette of color and ➤ The height limit imposed by the City required the team to squeeze the geometric complexity.” floor-to-floor height to 8 ft, 10 in. at the five levels of bedrooms. The —Brian Raff steel frame allowed the design to incorporate “coffered” ceilings to gain height. Even with that tactic, the ceilings were within a couple inches of the maximum allowed height ➤ Green roofs with heavy dead loads required structural steel framing. Heavy planter loads on the courtyard over parking required heavy structural beams Using split levels allowed high ceilings in the living, dining and kitchen spaces, with lower ceiling heights in the bedroom and bath areas. The use of green materials was of the utmost importance for the project, and structural steel contributed heavily to the green requirements of the project with its high level of recycled content and capability to be reused or reclaimed and recycled into another product of equal or greater strength or quality at the end of its useful life. The use of 25,000 board ft of reclaimed African mahogany, fir and pine for doors, flooring, cabinets, trim and other architectural elements reinforces the green goals of the building. The sculptural aspects of the steel frame have always been a part of archi- tectural expression that has been lost or diminished during the cladding process of most steel-framed buildings. It was the designer’s goal to allow the beauty of the raw structure to be expressed within the requirements mandated by code and en- velope. As this goal was developed and combined with the weathering steel sid- ing, the building became much more in- teresting and alive. The patination of the steel adds great life and interest to the building as it develops its color in the arid Montana climate. Owner Eric & Cheryl Hefty, Missoula, Mont. Owner’s Representative, Architect and General Contractor Eric Hefty & Associates, Missoula, Mont. Structural Engineer Apex Engineering Services, Inc., Missoula, Mont. Photographs Mark Bryant Photographics and Eric Hefty & Associates

may 2013 MODERN STEEL CONSTRUCTION Merit Award—Less than $15 Million Twilight Epiphany (James Turrell Skyspace at Rice University), Houston, Texas

“This immaculate sculpture seems to defy the laws of physics.” —Brian Raff

he James Turrell Skyspace at Rice University (a.k.a. Minimizing the depth of the roof framing and aggressive- “Twilight Epiphany”) is a permanent outdoor experi- ly tapering the steel was critical to the project, as the artist Tential art installation consisting of a 72-ft by 72-ft out- carefully calculated sight lines to ensure that none of the top door roof atop a berm-like, two-level, below-ground view- roof surfaces are visible when viewed from the ground. The ing gallery. The Skyspace was conceived by artist James fixed restraints on the framing depth and profile, together Turrell to create an atmospheric experience integrating with the large cantilevers (nearly 25 ft along the diagonals), light, sound and space that complements the natural light made designing and detailing the steel framing a challenge. present at sunrise and sunset. Additionally, the Turrell Sky- The tapered steel beam geometry was perfectly determined space is acoustically engineered for musical performances. to follow the upper and lower roof slopes, with a consistent Visitors experience the Skyspace initially from a distance and small offset from the final surface. In addition to taper- and later by passing through tunnels into the main lower ing the steel wide-flange sections longitudinally, the top viewing area, where they can sit on granite benches and flanges of the beams perpendicular to the roof slope are peer through the bottom surface of the roof. The lower roof canted at the same angle as the top roof surface; the steel surface serves as a palate upon which ever-changing hues of was squeezed within a very tight architectural package, with light are projected to alter one’s perception of the surround- very small tolerances. ing sky as viewed through a 14-ft by14-ft oculus in the cen- The tapered roof geometry continues beyond primary ter of the roof. The project has received widespread critical steel several feet until the upper and lower roof surfaces acclaim and, perhaps more importantly, inspires delight and meet in a “knife edge.” For the last 2 ft to 3 ft of the wonder in its visitors. cantilever, there is so little depth that a tapered steel plate The structural system for the James Turrell Skyspace is with stiffeners is first used, and as the depth decreases only comprised of a 72-ft by 72-ft octa-symmetric, tapered, can- a flat horizontal plate extends about a foot further, until tilevering frame supported by eight slender, 6-in.-diameter finally the architectural top surface of the roof transitions to a HSS cantilevered (flagpole) columns. Two concentric rings of painted steel plate that forms the final foot of the cantilever. 5 steel girders support a series of tapered double cantilevers that The outer edge of this ⁄16-in. painted plate was sharpened reach out to the inner and outer roof edges. The lateral system to enhance the crisp appearance of the edge. The high- consists only of the eight cantilevered columns. The tapered performance plaster lower surface of the roof extends all the steel roof framing is fabricated from deconstructed (then built- way to the tip of the knife edge. The detailing of a seamless up and tapered) W18 and W24 sections, HSS5×3 perimeter transition from primary steel into an exposed architectural tubes and tapered stiffener plates that reach beyond the pri- surface that is simultaneously a structural cantilever was one mary beams out to the edges of the roof. of the project team’s greatest challenges.

MODERN STEEL CONSTRUCTION may 2013 Designing the structural steel to so closely match the archi- tectural roof profiles required close coordination with the techni- cal architects and full detailing of all connections, primary and secondary miscellaneous steel members alike. The geometry of all steel and connections was fully specified in the structural con- tract drawings, leaving no interpretation to the fabricator. The use of structural steel on Skyspace allowed the artist and design team to push the outer limits of cantilever span and slenderness, all the while concealing the structure, to give the impression of a roof almost magically floating in the air. The slen- derness of the columns—combined with the huge cantilevers and sight lines, which hide the structural depth—creates an im- pression so dramatic that visitors are often puzzled by how the roof stands up. Owner/Developer Rice University, Houston Architect Thomas Phifer and Partners, New York Artist James Turrell Structural Engineer Skidmore, Owings & Merrill LLP, Chicago General Contractor Linbeck Construction Group, LLC, Houston Photographs Skidmore, Owings & Merrill LLP and Thomas Phifer and Partners

may 2013 MODERN STEEL CONSTRUCTION helsea Piers Connecticut accommodates pretty much all Csporting tastes. The 400,000-sq.- ft facility in Stamford, Conn., opened to the public in the summer of 2012 and features two NHL regulation ice rinks, enormous turf fields (for soccer, lacrosse, football, field hockey, softball and baseball), a 20,000-sq.-ft gymnastics center, an aquatics center with an Olympic-sized pool, seven tennis courts, twelve squash courts, a trampoline center, a baseball/softball training area, childcare/preschool, food service, pro shop, catering and party/special event spaces. The building housing this state-of-the- art sports facility is a 45-year-old manu- facturing plant previously used by Clairol as the facility for manufacturing Herbal Essence shampoo. The adaptive reuse saved the old building from being demol- ished and ending up in a landfill; Clairol maintained the building well, keeping it in excellent condition. Although the building square footage met the project’s requirements, the lack of large column-free spaces created a poten- tial roadblock. Professional quality sports fa- Presidential Award of Excellence in Engineering cilities such as swimming pools, hockey rinks Chelsea Piers Connecticut, Stamford, Conn. and tennis courts require large column-free areas in excess of a 100 ft wide. This criteri- on required the removal of 23 columns from the building in order to achieve the column- Great innovation and an adaptive free zones. Determining an economical “ method for removing the existing columns reuse of an abandoned space. while leaving the entire roof structure in place was the principal challenge. The solu- An idea that can be replicated. tions selected by WSP Cantor Seinuk were ” extremely creative, economical and highly —Mark Simonides sustainable, resulting in reuse of the existing roof structure, limited demolition and mini- mization of new materials. The proposed structural system was based upon the use of king post trusses constructed out of the in-place existing roof structure. Leaving the existing beams, which formed the top compression chords of the truss, in place and using a portion of the existing columns as the king posts, only a relatively small amount of steel had to be added to form the tension cords of the truss. Upgrading of the in-place top chord members was accomplished via composite action with the new concrete slab poured on the existing in-place metal roof deck. Steel angle members were used for the tension chords of the trusses. Although the simple and basic “off the shelf” structural members remain exposed, their aesthetically pleasing form is apparent. The positive effect of the forms on the facility’s

MODERN STEEL CONSTRUCTION may 2013 may 2013 MODERN STEEL CONSTRUCTION architecture is further testament to the economic and sustainable accomplishments achievable via innovative engineering. It is an excellent example of form following function. The design met all the crite- ria—with the exception of be- ing able to achieve a flat floor after the concrete was poured. Since the existing roof, which was supported upon the new king post trusses, was slated to become additional space for the new sport facilities, there was a requirement for a very flat floor structure. The proposed eloquent solution, calling for the cambering of the trusses prior to pouring the concrete slab, was accomplished via jacking of the existing roof structure prior to the installation of the new truss members. After the installation of the truss steel, the existing col- umns were cut out and removed. Upon pouring the new roof con- crete the trusses deflected pre- cisely as designed, leaving a flat surface for the tennis courts and soccer area to be located above. Chelsea Piers Connecticut embodies innovative, sustain- able engineering for building reuse and development. A for- ward-thinking design team cou- pled with a supportive and moti- vated owner allowed this project to reach its full potential. The result is a state-of-the-art facil- ity serving the athletic needs of the community while forming a viable anchor business in a once abandoned industrial facility. Owner Chelsea Piers, New York Architect James G. Rogers Architects, South Norwalk, Conn. Structural Engineer WSP Cantor Seinuk, New York General Contractor AP Construction, Stamford, Conn. Steel Detailer WSP Mountain Enterprises, Inc., Sharpsburg, Md. (AISC Member) Photographs Chelsea Piers WSP Mountain Enterprises, Inc. MODERN STEEL CONSTRUCTION may 2013