Inelastic Earthquake Response of Asymmetric Structures

Abstract

The inelastic seismic response of a class of one‐way torsionally unbalanced structures is presented. The structural model consists of a single mass supported by bilinear hysteretic elements. The yield strength of the model is a function of the lateral period and follows a trend similar to the design strengths suggested by design codes. The response parameters of interest are the resisting element ductility demands and the edge displacement of the model. The sensitivity of the response parameters to system parameters, such as structural eccentricity, yield strength, uncoupled lateral period, and uncoupled torsional to lateral frequency ratio, is examined for two types of ground motions. It is found that the effect of asymmetry is most pronounced for stiff structures with low yield strength. Unlike elastic response, the uncoupled torsional‐to‐lateral‐frequency ratio is not a sensitive system parameter that affects the inelastic responses. Exceptionally large ductility demand can be expected on eccentric stiff structures with low yield strength when exposed to ground motions with large and long duration acceleration peaks as exemplified by the 1977 Romanian earthquake record.