地震波斜入射下考虑场地非线性、地形效应和土结动力相互作用的大跨连续刚构桥地震响应分析

基于多源叠加粘弹性人工边界和等效线性化理论，建立了SV波斜入射下考虑场地非线性、地形效应和土-结构动力相互作用的大跨结构动力响应分析计算方法。该文首先给出了SV波斜入射下非线性场地的自由场等效线性化求解方法，然后利用ANSYS有限元软件对一座5跨连续刚构桥和场地建立了有限元模型，计算了考虑场地非线性情况下不同入射角、不同地形和不同场地刚度工况下连续刚构桥的动力响应。计算结果表明:桥墩轴力随着入射角的增大而增大，剪力则随着入射角的增大而减小；局部地形不规则程度对桥梁结构内力放大效应有所不同，地形变化越剧烈，放大效应越明显；土体刚度对考虑土-结构动力相互作用的桥梁结构动力响应有较大影响，土体越软，土-结构动力相互作用效应越明显。

SEISMIC ANALYSIS OF LONG-SPAN CONTINUOUS RIGID FRAME BRIDGE CONSIDERING SITE NONLINEARITY,TOPOGRAPHY EFFECT AND SOIL-STRUCTURE DYNAMIC INTERACTION UNDER OBLIQUE INCIDENCE

Based on viscous-spring superposition artificial boundary and equivalent linear theory, a method for calculating the seismic response of long-span structures considering the nonlinear behavior of site, topography and soil-structure interaction effects under oblique incidence is established. Firstly, an equivalent linear method to obtain nonlinear site response under oblique SV wave incidence is introduced. Then, by using ANSYS software, a finite element model including a five-span continuous rigid frame bridge and soil profile is established. With the consideration of nonlinear soil behavior, a series of numerical simulation is performed with different topographies and site stiffness under different incident angles. The results show that the axial force increases and shear force decreases as the incidence angle goes up; the amplification of displacement response varies with different local irregular topographies. The amplification resulted from steep topography is larger than that from gentle topography. Site stiffness also has a great impact on the response of bridges and soft soils lead to much more pronounced responses than hard soils do.