支座摩阻效应对大跨长联连续梁桥地震反应的影响分析

为了解支座摩阻效应对长联大跨连续梁桥地震反应的影响,并得出可应用于工程的相应简化计算方法,以处于高烈度区的某铁路大跨长联连续梁为工程背景,按照不计与计入活动支座摩阻效应两种工况,利用Midas/Civil软件建立结构的三维空间杆件模型,并选用软件中的两种双线性理想弹塑性单元模拟支座的摩阻,采用非线性时程分析方法,对结构进行多遇地震下的地震反应分析。分析结果表明,对于这种设置1个固定墩的大跨长联连续梁结构,是否计入活动墩的支座摩阻效应对固定墩的设计影响很大,设计中需要考虑活动墩的支座摩阻。对于此类结构采用反应谱法进行多遇地震下的抗震计算时,活动墩顶的水平地震力可以直接用支座承受的竖向力乘以给定的支座摩阻系数,固定墩顶的水平力用反应谱计算值减掉活动墩水平摩擦力之和的0.8倍,可以满足工程设计精度要求。

Analysis of Sliding Bearing Friction Effect on Seismic Behavior of Long and Large-Span Continuous Bridges

With reference to a long and large-span continuous bridge used in a high-intensity area,a three-dimensional space model of the structure is established with Midas/Civil software to understand the effect of bearing friction on the seismic response of the bridge,and to obtain the corresponding simplified calculation method applicable to engineering according to two kinds of working conditions about the sliding bearing friction. Two bilinear ideal elastic-plastic elements in the software are used to simulate the friction of the bearing,and nonlinear time-history analysis method is employed to analyze the seismic response of the structure under earthquake. The analysis results show that the effect of the friction of movable piers on the design of the fixed pier is significant for large span continuous beam structure with a fixed pier,and the design needs to consider the bearing friction of the movable pier. For this kind of structure,the horizontal seismic force of the movable bearing can be obtained with the vertical force of the bearing directly multiplied by the given bearing friction coefficient. The horizontal force of the fixed pier can be calculated with the response spectrum minus 80% of the sum of the horizontal friction of the movable piers,which can meet the engineering design precision requirement.