SEISMIC PERFORMANCE EVALUATION OF REINFORCED CONCRETE FRAME STRUCTURES USING THE ENDURANCE TIME METHOD

The endurance time method (ETM) is characterized by the increase in seismic intensity with respect to time. Three endurance time accelerograms (ETA) were generated based on the national seismic design spectra by using the nonlinear least-square method. Two reinforced concrete frame structures configured with 5 and 12 stories were employed as case studies. Incremental dynamic analyses of structures subjected to 22 ground motions and nonlinear dynamic analyses of structures subjected to three ETAs were carried out. The comparisons of the maximum roof displacement, the maximum interstory drift ratio, the maximum base shear and structural hysteretic energy for different seismic intensities were performed, as well as the comparison of the distribution of the maximum interstory drift ratio and the maximum story shear for severe seismic hazard levels. Results showed that the dispersion of seismic response is low and the results of ETM match well with the median response induced by real ground motions, indicating ETM predicts structural seismic responses with good accuracy. Since ETM derives the seismic response for different seismic hazard levels using only one nonlinear analysis with a high level of computational accuracy and efficiency, it provides a new effective tool for seismic performance evaluation of structures.