Seismic Response of Ultra High-Pier Railway Bridge under Spatially Varying Site Conditions of Earthquake Excitations

Abstract

An ultra high-rise pier railway bridge in Guizhou province, China, is selected as an engineering example to study the effect of spatially varying site conditions on the seismic performance of mountainous ultra high-rise pier railway bridges. A seismic performance analysis and a numerical simulation of the bridge are conducted while subjecting the bridge to spatially varying site conditions using the pseudo excitation method. The influence of the distribution of different spatially varying combinations of firm, medium, and soft site conditions on the stochastic seismic response of this type of bridge is then considered for seismic analysis under multi-directional earthquake excitations. Results show that (1) combinations of different site conditions have varying influences on the seismic response of the ultra high-rise pier railway bridge, and in particular, the influence of local site conditions has the greatest structural response on the highest pier; (2) it is of considerable importance to avoid the most unfavorable condition of soft soil beneath the highest pier, and to avoid hard soil conditions beneath other piers; and (3) to ensure that structural responses are not underestimated, it is necessary to consider the spatially varying site conditions when conducting a seismic analysis of ultra high-rise pier railway bridge structures that are likely to be subjected to earthquake action.