Study of bridge-subgrade longitudinal constraint range for high-speed railway simply-supported beam bridge with CRTSII ballastless track under earthquake excitation

Abstract

Owing to widespread applications of continuous welded rail (CWR) in high-speed railway bridges, the studies on the seismic response of high-speed railway simply-supported beam bridges (HSRSSBB) considering track constraint is of greatest importance. In order to ensure the high efficiency and high precision of calculations under the consideration of constraint of a long track system, based on the consideration of longitudinal constraint and beam-track interaction, an equivalent model for the HSRSSBB was established, which can simultaneously achieve high calculation efficiency and calculation precision. Also, the sensitivity for seismic response of the HSRSSBB had been proposed, and a judging formula to rapidly determine the bridge-subgrade longitudinal constraint range for the HSRSSBB was established. Finally, after an analysis of a large number of cases, the relationship between the equivalent boundary characteristics and the bridge-subgrade longitudinal constraint range was studied, indicating that the subgrade length of 90 m can be used as the reasonable subgrade length in the longitudinal seismic analysis for the HSRSSBB.