基于构件合力的曲线梁桥最不利激励方向确定

Resultant Response-based Method for Assessing the Critical Excitation Direction of Horizontally Curved Bridges

摘要:

为弥补以构件响应分量作为判别标准的结构最不利激励方向确定方法在实际工程应用中的不足，提出一种以构件合力（位移）为判别标准的结构地震动最不利激励方向确定方法.基于反应谱理论，推导出该方法的计算公式.以一座典型的曲线梁桥为例，建立了全桥有限元模型，应用该方法确定曲线梁桥的最不利激励方向并与多方向线性时程分析结果进行对比.研究结果表明，基于构件合力的结构地震动最不利激励方向确定方法可以综合反映构件整体的受力性能随地震动激励方向的变化情况，计算量相对较小且具有较高的可靠性；当以构件合力（位移）作为判别标准时，按照现行规范规定的地震动激励方向对曲线梁桥进行抗震性能验算,发现能够满足实际工程抗震设计的需要. 关键词： 曲线梁桥； 最不利激励方向； 合力； 构件； 反应谱法

Abstract:

Some methods for determining the critical excitation direction of structures regard the response along principal axes of components as the judging criterion, which have some limitations in the practical engineering application. To fill in this gap, a resultant responsebased method was proposed. Based on the response spectrum method, formulae for this method were derived. A typical horizontally curved bridge was selected as the case project, and the finite element model for this bridge was built. The critical excitation direction of the bridge was assessed by applying the resultant responsebased method and the results derived from this method were compared with those obtained from the linear time history analyses at multiple ground motion orientations. Results indicate that the resultant responsebased method can comprehensively reflect the variation of mechanical performance of the bridge component with the seismic excitation direction and has advantages of minor computational efforts and higher reliability. When regarding the resultant response as the judging criterion, adopting the excitation directions recommended by the current code for dynamic analyses of curved bridges can satisfy the seismic design requirement of practical engineering.