Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings
The project “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER-CEA Project,” is a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research (PEER) Center and funded by the California Earthquake Authority (CEA).
Quantifying the difference of seismic performance of unretrofitted and retrofitted single-family wood-frame houses is important in California due to the high seismicity of the state. Inadequate lateral bracing of cripple walls and inadequate sill bolting have been observed to be primary reasons for damage to residential homes even in moderate earthquakes.
The overall objective of the PEER–CEA project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors.
A technical overview of the project is documented in PEER Report 2020/12, “Project Technical Summary,” written by Evan Reis in collaboration with Yousef Bozorgnia, Henry Burton, Kelly Cobeen, Gregory G. Deierlein, Tara Hutchinson, Grace S. Kang, Bret Lizundia, Silvia Mazzoni, Sharyl Rabinovici, Brandon Schiller, David P. Welch, and Farzin Zareian.