PEER has just published Report No. 2020/15: "Development of Testing Protocol for Cripple Wall Components," a report for the "Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings" Project. It was authored by Farzin Zareian and Joel Lanning, Department of Civil and Environmental Engineering, University of California, Irvine.
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER) and funded by the California Earthquake Authority (CEA). The overall project is titled “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.”
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.
This report is a product of Working Group 3.2 and focuses on Loading Protocol Development for Component Testing. It presents the background, development process, and recommendations for a quasi-static loading protocol to be used for cyclic testing of cripple wall components of wood-frame structures. The recommended loading protocol was developed for component testing to support the development of experimentally informed analytical models for cripple wall components. These analytical models are utilized for the performance-based assessment of wood-frame structures in the context of the PEER–CEA Project.
The recommended loading protocol was developed using nonlinear dynamic analysis of representative multi-degree-of-freedom (MDOF) systems subjected to sets of single-component ground motions that varied in location and hazard level. Cumulative damage of the cripple wall components of the MDOF systems was investigated. The result is a testing protocol that captures the loading history that a cripple wall may experience in various seismic regions in California.