一致激励下大跨度连续钢桁架柔性拱桥空间地震响应分析

Spatial Seismic Response Analysis of Large-span Continuous Steel Truss Flexible Arch Bridge Under Uniform Excitation

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一座大跨度连续钢桁架柔性拱桥在一致激励不同地震工况作用下的空间地震响应。研究结果表明:一致激励作用下,拱肋轴力、主桁弯矩峰值均出现在拱脚和边墩附近,拱肋横向位移峰值出现在每跨拱顶截面,纵向位移峰值沿桥长变化平缓;横向激励对横向位移影响大,对纵向位移影响小,纵向激励对纵向位移影响较大,对横向位移影响较小,竖向激励对水平位移影响较小;地震波组合输入对结构内力影响较单向输入大。建议在大跨度连续钢桁架柔性拱桥抗震设计中充分考虑地震空间特性,提高桥梁横向刚度,优化拱脚、边墩附近结构设计。

Based on the basic analysis theory of seismic response for multi freedom spatial structure system,the spatial finite element model was established by ANSYS and the spatial seismic response under uniform excitation with different seismic load conditions for large span continuous steel truss flexible arch bridge was analyzed by the dynamic time history analysis method.The analysis results show that under uniform excitation,the peak values of axial force of arch rib and bending moment of main truss appear around arch foot and side of pier.The peak value of transverse displacement of arch rib appears in top section for arch rib of each span,the peak value of longitudinal displacement changes gently along the bridge.Transverse excitation has great influence on transverse displacement and has little influence on longitudinal displacement,longitudinal excitation has great influence on longitudinal displacement and has little influence on transverse displacement,vertical excitation has little influence on horizontal displacement.Combination of seismic has bigger structural internal force than single seismic.It is recommended to consider spatial characteristics of seismic and strengthen the transverse rigidity and optimize structural design around arch foot and side of pier during the seismic design of large span continuous steel truss flexible arch bridge.