Seismic Analysis of Elastoplastic MDOF Structures

Abstract

Approximate methods for the estimation of maximum story drift in elastoplastic multidegree‐of‐freedom (MDOF) shear buildings are examined. The structures considered have fundamental periods in the range of 0.4–4.0 seconds and have one, two, three, five, and ten degrees of freedom. Responses for maximum ductility levels of one (elastic), two, five, and ten are considered. Two methods for predicting the maximum story drift are developed and evaluated. In the first method, the response of the multidegree‐of‐freedom inelastic system is estimated by applying two deamplification factors to the elastic spectrum of the single degree‐of‐freedom system. The second technique identifies an equivalent linear multidegree‐of‐freedom system. The effects of the number of degrees of freedom and the maximum ductility level on the deamplification factors and the equivalent linear parameters are described.