Comparative analysis of steel arch bridges under near-fault ground motion effects of directivity-pulse and fling-step

Abstract

In this study, it is intended to investigate specifically the directivity-pulse and fling-step characteristics of near-fault ground motions on deck-type steel arch bridges. As known, near-fault ground motions have different dynamic characteristics than far-fault ground motions characterized by directivity pulse and fling step effects which usually have important effects on structural systems. The New River Gorge Bridge constructed in the USA is selected as a numerical example to determine the response of this type of steel arch bridges under the specified characteristics of near-fault ground motions. As near-fault ground motions 1999 Chi-Chi Earthquake strong ground motion recordings of TCU102, TCU089 and HWA032 are used. The bridge responses obtained for the near-fault ground motions showing directivity-pulse and fling-step characteristics are compared with each other and with those of the responses obtained for the far-fault ground motion to emphasize the relative importance of directivity-pulse and fling-step effects. The results revealed that both directivity-pulse and fling-step characteristics of near-fault ground motions have considerable effects on steel arch bridge responses and therefore should be taken into account in the design phase of these bridges.