Linear Models to Predict the Nonlinear Seismic Behavior of a One-Story Steel Frame

摘要

In this report, six methods of linearization are used to construct various equivalent linear models to predict the nonlinear seismic behavior of a one-story steel frame which was constructed and tested by Sveinsson and McNiven at the Earthquake Engineering Research Center of the University of California, Berkeley. Four of the methods of linearization depend on the restoring force-displacement relation of the frame. Two bilinear models are constructed; one to represent the elastic-plastic nature of the structural steel, the other to represent the work hardening nature. Both bilinear models reproduce the response time histories quite accurately in the domain appropriate to each. The models are assessed by comparing their response predictions with the measured response for the El Centro, Pacoima, Taft and Parkfield excitations. The study indicates that the dependence of the nonlinear response of a structure on the characteristics of the earthquake excitation is so complex that there is no way that the linearization schemes considered can have the required generality to limit the maximum displacement response to a specified value. Nonetheless, these methods can provide very valuable guidelines for design, if their limitations and relationship to the overall design process is fully recognized.