Influence of Earthquake Source Parameters and Damping on Elastic Response Spectra

In this paper the influence of effective duration of strong motion, soil condition, magnitude and shape of accelerogram time history on elastic response spectra have been investigated. A total of 106 Iran’s horizontal acceleration components strong motion records are selected. These accelerograms are categorized in accordance with their earthquake parameters and soil condition of recording station and the influence of different soil conditions are plotted in graphs. The influence of damping ratio on the response spectra is also investigated. Analytical results show that the influence of soil condition is very significant on the shape of response spectra. The influence of effective duration of strong motion has been studied by definition based on energy of accelerogram. It can be seen that an increase in effective duration, causes reduction in the slope of response spectra in long period part and increases the spectral values. The effect of damping on response spectra is presented by special coefficient, which depends on the period of the structure, soil condition and damping ratio