基于有限元模拟混凝土徐变对预应力组合箱梁的影响研究

Study on the Effect of Concrete Creep on Prestressed Composite Box Girder Based on Finite Element Simulation

以某桥梁工程为例,分析了长期荷载作用下混凝土收缩徐变对波形钢腹板预应力组合箱梁的影响。采用有限元软件Midas/FEA3.70进行建模,通过Midas/FEA中的时间依存材料来定义混凝土的收缩徐变系数,分析了长期荷载作用下混凝土收缩徐变对波形钢腹板预应力组合箱梁挠度和内力重分布的影响。得出以下结论:长期收缩徐变对挠度的影响主要发生在成桥阶段至运营10年之间,2个中跨跨中附近截面的挠度变化幅度最大;经过长期的收缩徐变,混凝土顶、底板所受轴力减小,波形钢腹板轴力增大;混凝土预制板养护周期越长,收缩徐变对结构变形和内力重分布的影响就越小。

Taking a bridge project as an example, the influence of concrete shrinkage and creep on prestressed composite box girder with corrugated steel webs under long-term load was analyzed. The finite element software MIDAS/FEA3.70 was used for modeling, and the shrinkage and creep coefficient of concrete was defined by time-dependent materials of MIDAS/FEA. The influence of concrete shrinkage and creep on the deflection and internal force redistribution of prestressed composite box girder with corrugated steel webs under long-term load effect were analyzed. The following conclusions are drawn: the influence of long-term shrinkage and creep on the deflection mainly occurs between the completion stage and 10 years of operation, and the deflection of the section near the middle of the two mid-spans has the largest variation range. After long-term shrinkage and creep, the axial force of the concrete roof and floor decreases, while one of the corrugated steel web increases. The longer the curing period of precast concrete slab is,the less the effect of shrinkage and creep on the deformation and internal force redistribution of the structure is.