UC Berkeley's California Memorial Stadium: Seismic Strengthening of an Historic Structure Residing over an Active Fault

Abstract

UC Berkeley's California Memorial Stadium, constructed in 1923 and designed by the renowned architect John Galen Howard, sits directly over the northern segment of the Hayward Fault. After many years of analysis, politics, litigation and even an 18 month much-celebrated tree sitting protest, the campus authorized the advancement of the seismic safety corrections for the Stadium. Situated at the opening of Strawberry Canyon, with the eastern half of the stadium literally carved into the hillside, the non-ductile concrete frame western stadium bowl will be seismically retrofitted and modernized with new seating bowl framing, a new press box, and with the preservation and restoration of the historic perimeter concrete wall. The truly unique aspect of the retrofit design is the approach to the sections of the stadium positioned over the north-to-south running, right-lateral Hayward Fault. The planned retrofit design creates separate rupture zone blocks, gapped and separated by joints from the adjacent sections of the stadium. The FRB's will be reinforced with stiffening concrete shear walls bearing on a monolithic flat mat slab foundation, all bearing on a plastic membrane to reduce friction and thus facilitate the independent twisting and tilting that may result from the predicted 6 feet of horizontal fault rupture displacement and 2 feet of vertical fault rupture displacement. An adjacent crescent-shaped building named the Student Athlete High Performance Center, currently under construction, and the retrofit of California Memorial Stadium are designed in strict compliance with the State of California's Alquist-Priolo Seismic Zonation Act (APZA). GEOLOGIC DESCRIPTION California Memorial Stadium is located at the mouth of Strawberry Canyon, directly along the break in slope between the Berkeley Hills (on the east) and the piedmont underlying the central campus west of the hills. This topographic interface between the piedmont and the hills marks the general location of the Hayward fault. The Hayward fault forms a major structural boundary along the eastern side of UCB's central campus,