Peak distribution of seismic response under horizontal and vertical excitations

In this paper, we investigated peak distribution of seismic response under horizontal and vertical excitations. The peak distribution is the parameter to estimate the results of fatigue evaluation for seismic responses. Two types of peak distributions were calculated from the seismic response histories in this study; the first was the conventional peak distribution obtained from seismic response histories, and the second was the distribution of the peak-to-peak range processed by rain flow counting. The seismic response histories used herein were simulated by using sine and random waves with different frequency properties. The distributions under bi-directional excitations were compared with those under single directional excitations. The comparison showed that the variation under bi-directional excitations was relatively larger than that under single directional excitations, and that the distribution of the relatively smaller range increased under bi-directional excitations. The result suggested that employing the seismic response history obtained from each directional excitation is more conservative than that obtained from bi-directional excitation for fatigue design which assumes maximum response. (author)