Abstrato

Responses of long-span rigid frame bridge under longitudinal excitation of near-field and far-field ground motion

Zhang Ailian, Zhang Linchun

This paper set a typical long-span rigid frame bridge as a research object and established a finite element model for the long-span rigid frame bridge using finite element software MIDAS/CIVIL. The near-field and far-field ground motions from four stations were recorded to study the responses of the bridge under the longitudinal excitation of nearfield pulse type ground motion, and they were compared with the responses under farfield ground motion excitation. It aims to analyze the response characteristics of long-span bridge under the two types of ground motions and investigate the response characteristics of the rigid frame bridge with taking the account of horizontal and three-dimensional ground motion effects. The results indicate that: The bridge response caused by near-field pulse type ground motion is greater than that caused by non-pulse type when at longitudinal input under the ground motion and recording the action at same accelerated speed peaks; under the excitation of near-field pulse type ground motion, there would be a great increase in bridge response. Different effects on different structural parts; PGV/PGA is a major parameter affecting structure response; attention must be paid to the impact from the medium and long cycle velocity pulse of near-field ground motion on long period and flexible structure; near-field pulse type ground motion also has significant impact on longitudinal displacement at mid-span and pier top. All these phenomena shall be considered during the aseismic design for near-field rigid frame bridge appropriately