900t大型预制箱梁早期张拉抗裂性能研究  

Research on the Cracking Resistance Behavior of 900 t Large-Scale Precast Box Girders during the Early Stage Tensioning

作　　者：卢文良[1] 李劲松[2] 张兰青[2] 杨独 

机构地区：[1]北京交通大学土木建筑学院,北京100044 [2]兖州中材建设有限公司,山东兖州272100 [3]北京中联环工程股份有限公司,北京100037

出　　处：《中国铁道科学》2010年第5期41-46,共6页China Railway Science

基　　金：铁道部科技研究开发计划项目(2005K002-C-1)

摘　　要：运用数值方法和现场测试,研究900 t大型预制预应力混凝土双线简支箱梁在预、初张拉过程中的应力、变形状态及抗裂性能。采用通用有限元分析软件MIDAS/Civil,按弹性支撑计算模型,对预、初张拉阶段箱梁的应力和变形状态进行模拟计算,分析基础刚度、箱梁翼板有效宽度及混凝土弹性模量关键参数对计算结果的影响。在箱梁跨中截面内埋设钢弦式应变计,在梁顶面布置观测标,监测预、初张拉阶段的混凝土应变和梁体变形。研究结果表明,900 t大型预应力混凝土双线简支箱梁跨中截面在预、初张拉阶段未出现拉应力,初张拉后箱梁明显上拱。采用只受压弹性连接模拟箱梁与台座之间的接触关系进行箱梁受力状态分析,能够模拟出梁体在预应力束逐批张拉下梁体逐渐起拱以及梁体自重逐渐参与作用的实际情况,梁体上拱变形的计算结果与实测结果符合较好。Based on the numerical method and the field tests,research was conducted on the stress,the deformation state and the crack resistance behavior of 900 t large-scale precast simply supported box girders during the pre-tensioning and the initial tensioning stages.Finite element models with the elastic supported springs were created by using the popular FEM software MIDAS/Civil.The structural behaviors including the stress and the deformation state during the pre-tensioning and the initial tensioning stages were simulated.The influences on the calculation results causing by different values of key parameters,such as the foundation stiffness,the effective width of the box girder flange plate and the concrete elastic modulus were analyzed.Vibrating wire strain gauges were embedded in the mid-span section to monitor the concrete strain and observing buoys were marked on the top surface of the girder for deformation observation during the same stages.The research results showed that there were no tensile stresses in the critical mid-span section of the 900 t precast simply supported box girder during the pre-tensioning and initial tensioning stages,the box girder was arched obviously after the initial tensioning.It is reasonable that the compressed elastic springs are used to simulate the contact relationships between the box girder and the pedestal.This method can simulate the girder behavior of gradually arching during the prestressing stages and the phenomenon of gradually loading of dead load can also be simulated.The calculated results of girder arching deformation agree well with the observed data.

关 键 词：大型箱梁 早期张拉 抗裂性 应力监测 有限元分析 

分 类 号：U448.213[建筑科学—桥梁与隧道工程]