施工过程对钢管混凝土桁式拱桥长期静力性能的影响

Influence of construction process on long-term responses of CFST trussed arch bridges

随着钢管混凝土拱桥跨度的不断增大,拱肋核心混凝土收缩徐变作用对拱肋静力性能的影响更加显著。采用欧洲规范EC2混凝土收缩徐变模型与逐步积分法模拟混凝土收缩徐变性能。将EC2模型与逐步积分法通过UMAT二次开发程序引入ABAQUS中,同时考虑施工过程、施工过程中加载龄期的变化、轴力与弯矩组合作用下构件的长期效应、几何与材料非线性等因素,建立了较为精确的钢管混凝土拱桥长期静力性能有限元分析模型。通过将分析结果与实测数据进行对比,验证有限元分析模型的可靠性。采用该有限元分析模型,分析施工过程对钢管混凝土拱桥长期静力性能的影响,结果表明,施工过程中的应力历史会显著增加拱肋长期位移、钢管应力与拱肋弯矩。在钢管混凝土拱桥长期静力性能分析中,应该考虑施工过程的影响,否则时效作用的影响将被大大低估。

As the span of concrete-filled steel tubular(CFST) arch bridge increases,time effects has a considerable influence on the static behavior of the arches.A refined finite element model was brought up to predict the long-term response of concrete-filled steel tubular(CFST) arch bridge accounting for the construction process,aging of concrete,time effects under both axial forces and moments,and geometric and material nonlinearities.The creep and shrinkage of concrete core for CFST arches was modelled using the Eurocode 2(EC2) model.The time-dependent behavior of concrete core under various stress history was simulated with the step-by-step method.The EC2 model and the step-by-step method were implemented in ABAQUS with the UMAT subroutine.The reliability of the model was benchmarked against site-measured data of real bridge application.With this model,the influence of the construction process on the long-term response of CFST arch bridges was investigated.It is noted that the construction process can significantly increase the long-term displacement of the arches,the stresses in the steel tubes,and the bending moment along the arch ribs.When discussing the time effects of the concrete core on the static response of the CFST arch bridges,construction process needs to be considered,otherwise considerable underestimation will be resulted.