UC Berkeley Memorial Stadium Press Box Wins National Architecture and Engineering Award
September 20, 2013 from American Institute of Steel Construction
(Chicago, IL) – The University of California, Berkeley’s Memorial Stadium press box has earned national recognition in the 2013 Innovative Design in Engineering and Architecture with Structural Steel awards program (IDEAS2). In honor of this achievement, members of the project team will be presented with awards from the American Institute of Steel Construction (AISC) during a ceremony at the project site on Friday, September 20, at 3 p.m.
Conducted annually by AISC, the IDEAS2 awards recognize outstanding achievement in engineering and architecture on structural steel projects across the country. The IDEAS2 award is the highest, most prestigious honor bestowed on building projects by the structural steel industry in the U.S. and recognizes the importance of teamwork, coordination and collaboration in fostering successful construction projects.
The project team members include:
Owner: The University of California, Berkeley, Calif.
Architects: HNTB Architecture, Inc., Los Angeles; and STUDIOS Architecture, San Francisco
Structural Engineer: Forell/Elsesser Engineers, Inc., San Francisco
General Contractor: Webcor Builders, San Francisco
Consultant: Hassett Engineering, Inc., Castro Valley, Calif.
Steel Fabricator and Erector: The Herrick Corporation, Stockton, Calif. (AISC Member/AISC Certified Fabricator and Erector)
Steel Detailer: SNC, Compton, Calif. (AISC Member)
The UC Berkeley California Memorial Stadium Press Box is a Merit award winner in the category of projects $15 Million to $75 Million, making it one of only eight projects around the country to receive the Merit honor. Each year, the IDEAS2 awards honor National and Merit award winners in three categories, based on constructed value: projects less than $15 million; projects $15 million to $75 million; and projects greater than $75 million. Each project is judged on its use of structural steel from both an architectural and structural engineering perspective, with an emphasis on: creative solutions to project’s program requirements; applications of innovative design approaches in areas such as connections, gravity systems, lateral load resisting systems, fire protection and blast; aesthetic and visual impact of the project; innovative use of architecturally exposed structural steel; technical or architectural advances in the use of the steel; and the use of innovative design and construction methods.
Built as a memorial to fallen alumni of World War I, California Memorial Stadium has endured as one of the most picturesque venues in college football from its opening in 1923 for the “Big Game” versus Stanford to the present day. After it was discovered that the stadium was at particular risk in the event of an earthquake, which is further exacerbated by the fact that it sits above the Hayward Fault, the university undertook a large project to seismically retrofit as well as modernize the stadium. As a part of this project, the western stadium bowl was seismically retrofitted and modernized with new concrete seating bowl framing while keeping the existing historic perimeter concrete wall in place.
The “crown-jewel” of the project, however, is the new long-span two-story structural steel press box that floats atop the new west portion of the stadium. One of the main architectural design goals was to achieve a floating effect to the press box by reducing the number of supports to a bare minimum. The resulting structure is 375 ft long with two 100-ft-long main spans and end-span cantilevers of 33 ft.
The press box arches to follow the curvature of the existing exterior wall and is supported by four concrete cores (two at each end) and four center structural steel columns. The press box is two stories with the first floor housing print, radio and TV media functions and the second floor housing a club space with views and seating facing the field, as well as a dramatic 25-ft cantilevered balcony with a glass deck that faces the campus and provides panoramic views of the San Francisco Bay and Golden Gate Bridge.
The areas of the levels are 10,200 sq. ft and 12,500 sq. ft, respectively. The main structure of the press box consists of a story-deep space truss that is comprised of radial trusses that are supported by primary trusses that span between the concrete cores and center columns. The occupant load for the entire press box is approximately 1,700 people, and more than 1,350 tons of structural steel were used in its construction. The overall construction cost for the project was $215 million, with the press box portion being $40 million.
Due to the stadium’s location above the active Hayward Fault, the design of the press box and supporting concrete cores used several design innovations to allow for increased seismic performance. The concrete cores that support the press box provide the main vertical access to it. These tall, slender support elements, with the lumped press box mass at the top, create a dynamic incompatibility with the surrounding bowl structure. If this incompatibility had not been properly addressed, a major seismic event could potentially cause substantial damage to the concrete cores directly below the support points for the press box. To avoid this scenario, the cores and press box structure were seismically separated from the surrounding bowl and allowed to move completely independent of the main bowl structure.
As the core wall system rocks in the event of an earthquake, the large drift angle of the cores would cause large bending and shear forces in the press box above. In order to alleviate these forces and economize the design, the press box was supported on steel pins at the center of each core. These pins allow the press box to pivot on the cores and minimize damage to the steel structure. Each 7-in.-diameter high-strength steel pin is sandwiched by five 100-ksi steel gusset plates. The entire press box structure is supported on 12 of these high-strength pin assemblies.
The top-level cantilevered balcony is also a space truss comprised of numerous small-diameter pipe sections. This balcony truss system, which includes seismic and out-of-plane bracing, has several multi-member joint connections with some joints connecting up to eight pipe members. Due to the complexity of these joints, coordination had to take place in a 3D platform (Revit and Tekla) between the fabricators and design team.
Thanks to the complex nature of the site and surrounding neighborhood, there was limited space on-site to allow for erection and construction of the press box. To address this issue, fabricator Herrick and general contractor Webcor Builders enlisted the help of one of the largest crawler cranes in the country (a 750-ton Liebherr crawler crane with a 276-ft boom and 65-ft counterweight extension) to erect the main press box truss in five large segments. The main space truss of the press box was assembled and welded on the playing field, adjacent to the seating bowl. Carefully selected splice locations were determined to ensure each of the five truss segments would be within the crane’s capacity for weight and reach. Each of the five segments exceeded 75% of the crane’s capacity and therefore were considered critical picks. The largest pick of the five segments was 165 tons at a 160-ft reach, which took the crane to over 95% of its capacity.
The stadium reopened on time for the 2012 football season.
“An overwhelming confluence of functional and structural challenges solved with the boldest single stroke possible – nothing timid about it,” commented Paul Dannels, FAIA, a founding principal of sdi structures, Ann Arbor, Mich., and a judge in the competition.
The 13 IDEAS2 winners for 2013 were chosen from nearly 100 submissions received from architectural and engineering firms throughout the U.S. Each submission is reviewed and award winners are selected by a nationally recognized panel of design and construction industry professionals.
The IDEAS2 award dates back more than 70 years to the earliest years of AISC’s existence. Roger E. Ferch, P.E., president of AISC, said, “The entire UC Berkeley California Memorial Stadium Press Box project team has shown how structural steel can be used to create structures that combine beauty and practicality. The result is a press box structure that serves the stadium extremely well, while providing an example of what can be achieved when designing and constructing projects with steel.”
High-resolution images of the UC Berkeley California Memorial Stadium Press Box project are available upon request by contacting AISC’s Tasha Weiss at 312.670.5439, [email protected]. To learn more about the IDEAS2 awards and to view all of this year’s winning projects, visit www.aisc.org/ideas2.
Photo Credit: Tim Griffith
For more information contact:
American Institute of Steel Construction
The American Institute of Steel Construction, headquartered in Chicago, is a not-for-profit technical institute and trade association established in 1921 to serve the structural steel design community and construction industry. AISC’s mission is to make structural steel the material of choice by being the leader in structural steel-related technical and market-building activities, including: specification and code development, research, education, technical assistance, quality certification, standardization, and market development. AISC has a long tradition of service to the steel construction industry of providing timely and reliable information.
130 East Randolph St. Suite 2000
Chicago IL 60601
Fax: 312.626.2402 www.aisc.org