Page 22

2013WinShotcreteEMag

2012 Outstanding Infrastructure Project california memorial Stadium By Nur Kasdi and Larry Totten Shome of the University of Californiaince 1923, California (Cal) MemorialStadium in Berkeley, CA, has been the (UC) Berkeley’s football team. Modeled after the Roman engineering marvel of the Colos- seum, the oval stadium is situated above the surrounding landscape on Berkeley’s hillside and features panoramic views of the San Fran- cisco Bay Area. Due to its age and historical significance, in November 2006, Cal Memorial Stadium was included on the National Register of Historic Places.1 While the stadium seemingly disregarded almost a century of time and remains in remarkable condition for its age, the seismicity risks in the area are a constant concern. Positioned directly on top of the active Hayward Earthquake Fault, which runs roughly from end zone to end zone, the stadium is subjected to annual horizontal fault Fig. 1: Overview of the existing historic walls during demolition and “creep” of up to 0.20 in. (5 mm). During significant excavation. A layer of shotcrete was later applied over the existing walls seismic events, the ground along the fault could in various thicknesses from 5 to 36 in. (127 to 914 mm) displace up to 6 ft (1.82 m) horizontally and 2 ft (0.61 m) vertically—with potential catastrophic impacts on the structure.2 Cal Memorial Stadium was in critical need of not only a seismic retrofit but also an upgrade to modern standards. In late 2010, UC Berkeley responded by apportioning $321 mil- lion for the Memorial Stadium improvements, with work scheduled to start in January 2011. In preparation, the California Golden Bears football team was temporarily moved to the AT&T Park in San Francisco for the duration of the 2011 football season. The stadium reopened in fall 2012. Work Scope A unique feature to the project was that while the majority of the existing structure was demolished and reconstructed, the outer perimeter wall had to remain in place to preserve the historic landmark. Johnson Western Gunite (JWG), a Superior Gunite Company, was assigned the task to install a heavily reinforced shotcrete layer over the historic Fig. 2: Type 1 preconstruction test panel was wall for seismic strengthening. The shotcrete composed of three curtains of No. 10 (No. 32M) overlay varied in thicknesses from 5 to 36 in. and No. 9 (No. 29M) reinforcing steel with (127 to 914 mm). Because the majority of the additional boundary reinforcing bar elements wall surfaces were exposed, a steel trowel finish 20 Shotcrete • Winter 2013


2013WinShotcreteEMag
To see the actual publication please follow the link above