Evaluation of the Effects of Ground Motion Duration on Structural Collapse

ABSTRACT This study investigates the effect of strong motion duration on the earthquake‐induced structural collapse in seven moment‐resisting frame buildings when subjected to a set of 269 recorded ground motions. Intensities necessary to produce collapse by each record as a function of their corresponding significant duration show a clear descending trend of collapse capacity with increasing duration for all buildings with a fairly strong negative correlation ranging from −0.32 to −0.61. However, it is shown that the observed descending trend, which prior studies have attributed to being the result of strong motion duration, is primarily produced by characteristics of the ground motions other than duration. Results indicate that once these other characteristics of the ground motion are accounted for, the improvements in the estimates of collapse obtained by adding the explicit consideration of strong motion duration are not significant, particularly when using the next generation of intensity measures that are much better correlated with structural collapse. It is concluded that while there are some effects of strong motion duration, they are very small and in most cases negligible, such that practically the same probabilities of collapse are obtained by using scalar intensity measures that are well correlated with collapse without the explicit consideration of the strong motion duration.