多点激励下大跨度连续钢桁架柔性拱桥空间地震响应分析

基于多自由度空间结构体系地震响应分析的基本理论,利用ANSYS建立空间有限元模型,采用动力时程分析法分析某大跨度连续钢桁架柔性拱桥在一致和非一致激励作用不同地震工况下的空间地震响应。研究结果表明:非一致激励作用下,拱肋轴力、主桁弯矩峰值出现在拱脚和边墩附近;地震波组合输入较其单向输入拱脚轴力和面内弯矩最大分别可达1.28和8.32倍;非一致输入较一致激励作用拱脚轴力和面内弯矩分别可达2.5和8.4倍;地震波横向输入较纵向输入横向位移峰值比可达2.4倍,纵向输入较横向输入纵向位移峰值比可达2.6倍;结构的支座形式对结构构件地震响应结果也有一定影响;建议大跨度钢桁拱桥抗震设计应充分考虑地震波的空间和时间效应。

Spatial Seismic Response Analysis of Long-span Continuous SteelTruss Flexible Arch Bridge Under Multi-Support Excitations

Based on basic theory of the seismic response of a multi-degree-of-freedom spatial structure system, the spatial seismic responses of a long-span continuous steel truss flexible arch bridge under uniform and non-uniform excitations are analyzed using the dynamic time-history analysis method and spatial finite element model created by ANSYS software. Results of analysis show that the peak value of the arch rib''s axial force and the main truss''s bending moment appear around the arch foot and side of pier under non-uniform excitation. Further results are as follows:the maximum axial force at the arch foot and the in-plane bending moment under the multi-directional input of a seismic wave are 1.28 and 8.32 times greater than those under single-directional input, respectively; the axial force at the arch foot and the in-plane bending moment under non-uniform excitation are 2.5 and 8.4 times greater than those under uniform excitation, respectively; the peak value of lateral displacement at the arch rib under the a transverse direction input is 2.4 times greater than that under a longitudinal direction input; while the peak value of longitudinal displacement at the arch rib under the input of longitudinal direction is 2.6 times greater than that under the input of transverse direction. The bearing form also has some influence on the seismic response of structure. Results show the necessity of considering the space and time effect of seismic waves during the seismic design of long-span steel truss arch bridges.