屈曲约束支撑对钢桁架拱桥抗震性能改善效果的研究

Effect of Buckling Restrained Braces on the Seismic Performance of Steel Truss Arch Bridges

为了探究屈曲约束支撑对上承式钢桁架拱桥抗震性能的改善效果,分别对采用普通钢支撑和屈曲约束支撑的两种钢桁架拱桥进行了罕遇地震作用下的非线性动力时程分析。在计算模型中,除了对桥面板采用S4R壳单元、对屈曲约束支撑采用T3D2桁架单元进行简化外,结构的其它部分均采用考虑剪切变形的B31梁单元进行模拟。分别在纵向和横向输入了1995年日本神户地震记录下来的Ⅱ类场地JRT-NS、JRT-EW和OGF-N27W波,对采用屈曲约束支撑和普通钢支撑的模型分别在轴力和位移等方面进行了对比分析,结果表明:在纵向地震激励下,采用屈曲约束支撑的结构较采用普通钢支撑结构的抗震性能改善效果甚微;在横向地震激励下,采用屈曲约束支撑的结构较采用普通钢支撑结构的抗震性能有明显的改善作用;且在考虑竖向地震作用时,采用屈曲约束支撑的结构也具有明显的抗震性能改善效果。

In order to study the effect of buckling restrained braces on seismic performance of upper-deck steel truss arch bridges,nonlinear dynamic time-history analysis of two steel truss arch bridges supported by common steel braces and buckling restrained braces（BRB）are carried out in this paper.The bridge deck is modeled by S4 Rshell element,the buckling restrained braces are modeled by T3D2 truss element,and other parts of the structure are modeled using B31 beam element considering shear deformation.The input waves included JRT-NS,JRT-EW and OGF-N27 W in longitudinal and transverse are accelerograms which are modified ground motions based on the records from the 1995 Hyogoken-Nanbu earthquake,respectively.The models of bridges with buckling restrained braces and common steel braces are compared on axial force and displacement and so on.The results show under longitudinal excitation,the structure supported by buckling restrained braces has little improvement on the seismic behavior compared with the structure with common steel braces.Under transverse ground motion,the structure supported by buckling restrained brace has obvious improvement on the seismic behavior compared with the structure with common steel braces,and the situation is the same for structures under vertical excitation.