Low-Rise Shear Wall Ultimate Drift Limits

Drift limits for low aspect ratio reinforced concrete shear walls are investigated by reviewing the open literature for appropriate experimental data. Based on the geometry of structures designed for protective purposes and concerns regarding their response during seismic loading, data are obtained from pertinent references for which the wall aspect ratio is less than or equal to approximately 1, and for which loading is cyclic in nature (typically displacement controlled). In particular, lateral deflections at ultimate load, and at points in the softening region beyond ultimate for which the load has dropped to 90, 80, 70, 60, and 50 percent of its ultimate value, are obtained and converted to drift information.

The statistical nature of the data is also investigated. For example, at ultimate load the median drift limit is 0.72 percent, and it increases to 1.84 percent when the load drops to 50 percent of its ultimate value. These data are shown to be lognormally distributed, and an analysis of variance is performed. The use of these statistics to estimate probability of failure for a shear wall structure is illustrated. Finally, a brief comparison of drift limit results with existing seismic design code requirements is presented.