自然环境温度作用下徐变对预应力混凝土桥梁挠度影响研究  

Research on Creep Influence on PC Bridge Deflection under Natural Ambient Temperature

作　　者：鲁薇薇[1] LU Wei-wei(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,成都610031

出　　处：《铁道标准设计》2018年第9期89-93,共5页Railway Standard Design

基　　金：铁道部科技研究开发计划重大课题(2008G031-K)

摘　　要：基于开展自然环境条件下徐变试验,对现行的和考虑温度影响的徐变模型对于自然环境温度条件的适用性进行检验。结合目前通用桥梁有限元程序,实现应用选取出的组合徐变模型将变温作用引入到铁路PC连续梁桥的徐变效应分析中。通过将基于组合徐变模型和《铁路桥涵钢筋混凝土和预应力混凝土结构设计规范》(TB10002.3—2005)分析得到的梁体挠度结果进行比较,探讨忽略实际环境温度变化对徐变影响可能导致的对铁路PC连续梁桥结构变形状态的认知偏差。研究结果表明:考虑变温影响后的徐变预测结果与自然环境条件下徐变试验结果更为贴近;不同变温历程下,PC连续梁桥梁体徐变挠度的变化趋势和挠度量值表现出明显差异;忽略桥址处自然环境温度变化对徐变影响,可能使设置的预拱度与实际产生较大偏差,有时甚至方向相反而加剧梁体上拱或下挠问题,严重影响桥上轨道的平顺性和桥梁结构的安全性。桥址处环境温度变化对施工、运营乃至后期维护期间的桥梁梁体徐变挠度的影响均较为明显,应予以考虑。The applicability of the existing creep prediction models is investigated based on experimental study on concrete creep under natural environment condition. The selected combination creep model is applied in the creep effect analysis of railway PC continuous beam bridges in combination with the current general bridge finite element program. In order to investigate the cognitive bias of deformation state of railway PC continuous beam bridge due to the neglect of actual temperature effect on concrete creep,the calculated deflections of bridge are compared based on the combination creep model and the Chinese current Code for Design of Reinforced Concrete and Prestressed Concrete Structures of Railway Bridges and Culverts（TB10002. 3—2005）. Research results indicate that the predicted creep coefficients considering the mutative environment temperature are more close to the experimental creep coefficients.The variation trend and magnitude of the bridge deflections caused by creep are obviously different under different temperature conditions. Because of the neglect of the effect of temperature change on creep,there is a large deviation between the pre-camber and the actual deflection of PC continuous beam bridge,and the bridge deflection may be increased because of the fact that the pre-camber is set in the opposite direction,which may lead to track irregularity and unsafe bridge structure. The ambient temperature change at bridge site has significant influence on the creep deflection of PC continuous beam bridge,which should be taken into account during the periods of construction, service and even maintenance.

关 键 词：铁路桥 预应力混凝土桥 徐变 挠度 组合徐变模型 自然环境温度 

分 类 号：U24[交通运输工程—道路与铁道工程] U448.35[建筑科学—桥梁与隧道工程]