ABSTRACT

Research purposes: The acceleration peak value (PGA) and velocity pulse of near fault ground motion, which is more destructive to the bridge structure, have great difference with the far field earthquake. Therefore, in order to guide the design of near-fault railway bridges such as the Sichuan-Tibet railway, the response characteristics and failure modes of railway continuous rigid frame bridges subjected to the near fault earthquake are obtained. Taking a typical continuous rigid frame bridge of Sichuan-Tibet Railway as the research object, the finite element model of the full bridge is established by using FRAME3D software, and the study on seismic response and failure modes of railway continuous rigid frame bridges subjected to near fault earthquake are carried out. Research conclusion: (1) The damage of the bridge structure subjected to near fault earthquake with energy pulse and abundant long period components is more serious than that of the bridge structure subjected to far field earthquake; (2) The relationship between the damage of the piers and the ratio of PGV and PGA is obvious. The larger the ratio is, the more serious the damage is. The ratio of PGV and PGA can be used as an important indicator for judging whether serious damage has happened on the structure. In near fault ground motions, the proportion that the ratio of PGV and PGA is greater than 0.2s is high, and the damage of the pier is serious; (3) The damage of the continuous rigid frame bridge under earthquake is mainly concentrated in the pier bottom, the pier top or the beam position; (4) In the seismic resistance of near-fault bridge structures, both the pulsed high-power input factor of near fault earthquake and the cumulative damage of high-strength low-cycle fatigue effect should be considered.