Quasi-Static Reversed Cyclic Response of Level and Stepped Cripple Walls

Abstract

Old residential buildings, such as those built before 1960, were commonly supported on cripple walls, which are walls constructed of short wooden studs between the foundation and first floor framing. For most of these old buildings, the inertial force developed by the horizontal earthquake ground motion must be resisted entirely by the cripple wall and wall-to-foundation connection. Past earthquakes in California have shown that unbraced cripple walls are particularly vulnerable due to insufficient lateral resistance, even for a moderate level of ground shaking. This paper summarizes the results of a test program conducted on level and stepped cripple walls. Specimens with details representative of current construction and retrofit were tested using displacement histories recommended for ordinary and near-fault ground motions. Key parameters of the test program included the height and slope of the cripple wall, gravity load level, stucco finish, loading history, and framing details for stepped cripple walls. Results from the test program are compared with current design values.