基于Pushover分析的群桩基础抗震性能分析方法  

A seismic performance analysis approach based on Pushover analysis for group pile foundations

作　　者：叶爱君[1] 鲁传安[2] 

机构地区：[1]同济大学土木工程防灾国家重点实验室,上海200092 [2]上海市隧道工程轨道交通设计研究院,上海200070

出　　处：《土木工程学报》2010年第2期88-94,共7页China Civil Engineering Journal

基　　金：国家自然科学基金项目(50878147)

摘　　要：把桥梁群桩基础作为一个整体构件,基于Pushover分析,提出群桩基础的抗震性能分析方法,建立承台底荷载模型和非线性群桩基础结构模型(弹塑性桩身模型、非线性边界条件),并提出衡量群桩基础抗震性能的双指标(位移延性系数和抗力增大系数)。根据这一方法,选取一个实际的桥梁群桩基础作为背景建立群桩基础的非线性结构模型以及一系列的荷载工况,计算各种荷载水平对应的群桩基础推倒曲线,并采用本文建议的位移延性系数和抗力增大系数进行抗震性能评价。结果表明:承台底的轴力和弯矩水平虽然对群桩基础的屈服状态和极限状态对应的水平力和位移有显著影响,但对整体抗震性能指标影响很小;在各种荷载水平下,群桩基础的位移延性系数和抗力增大系数都较小。Treating a group pile foundation as one entity component, an approach of seismic performance analysis for group pile foundations was developed, based on Pushover analysis. A load model and a nonlinear structure model （inelastic pile model and nonlinear boundary condition） for group pile foundations were established, and two specific seismic performance indices, displacement ductility factor and resistance amplification factor, were proposed. The seismic performance analysis of a real group pile foundation was conducted. Based on the nonlinear structural model of the group pile foundation, a series of load cases were developed, the corresponding Pushover curves, the displacement ductility factors, and the resistance amplification factors were calculated. The results indicated that, the axial force and bending moment at the bottom of the pile cap slightly influenced the seismic performance index, while their effects on the lateral force and displacement in yield and ultimate limit state were significant. The displacement ductility factors and resistance amplification factors were quite small under all types of loadings.

关 键 词：群桩基础 抗震性能 PUSHOVER分析 荷载模型 位移延性系数 抗力增大系数 

分 类 号：U442.55[建筑科学—桥梁与隧道工程]