Estimation of Maximum Inelastic Displacement Demands on SDOF Systems using Approximate Methods

摘要

This paper presents the evaluation of six approximate methods to estimate the maximum inelastic displacements of single-degree-of-freedom systems. Four methods are based on equivalent linearization and two methods on displacement modification factors. Exact results are compared to approximate results for systems with three different types of hysteretic behavior when subjected to a set of 264 ground motions recorded on firm sites in California. Mean ratios of approximate to exact maximum displacements as a function of period of vibration and as a function of displacement ductility ratio are used to evaluate the different methods and in particular to identify which methods produce better results. Results suggest that in the intermediate and long period regions four of the methods evaluated here provide reasonable mean results while in the short period region only two of the methods produce acceptable results. It is shown that a significant scatter exists in any of the methods, such that caution should be used when using these approximate methods.