ESTIMATION OF INCREMENTAL DYNAMIC ANALYSIS RESULTS USING ENDURANCE TIME METHOD

Endurance Time (ET) method is a relatively new Performance-Based Earthquake Engineering method for structural evaluation and design. In this method, the structure is subjected to a gradually intensifying accelerogram(s) and its performance is assessed based on the maximum time duration that it can meet the specified performance objectives. Using several single degree of freedom oscillators with different periods and damping and nonlinear characteristics and also several multistory frames from low-rise to mid-height buildings, it is shown that ET can estimate results of the Incremental Dynamic Analysis (IDA) with acceptable accuracy. Spectral acceleration has been considered as the intensity measure. While the IDA would require several nonlinear dynamic analyses under multiple suitably scaled ground motion records, the ET can practically estimate the seismic behavior of simple to complex systems only by few nonlinear time history analyses. The results show that this method has the benefits of time history analysis and simplicity of the nonlinear static methods and can potentially be a useful tool for evaluating and designing seismic resistant structures.