施工阶段大跨径预应力混凝土刚构桥腹板开裂机理

摘要

Web cracking mechanism of long span rigid-frame prestressed concrete bridge construction stage was presented.Based on the elasticity theory,the 2-D stress function of web under patching load was deduced,the function curve of the horizon stress of different coefficient (d/a)was drawn,then a horizon stress function was fitted,and the method of equivalent pressure prism selection method was put forward.Later the 3-D situation horizon stress along the tendon line was considered based on 2-D horizon stressfunction.To verify the theory function,0 ~ 3 # rigid frame bridge segment finite element model wasestablished,the concrete web cracking analysis was carried out in different prestressed level.The resultsshowed that the crackling area of the web in the bridge was coincided with the finite element analyze,thelower limit stress of the finite analysis was also coincided to the theory calculated of transverse stressfunction put forward by this paper.%进行了大跨径预应力混凝土刚构桥腹板开裂机理研究，基于弹性力学平面问题分析方法，推导了集中荷载作用下的板件应力函数表达式，绘制了不同受压边长与集中荷载长度比（d／a）下的横向应力曲线，拟合了集中荷载作用下构件的横向应力求解函数，构造了混凝土刚构桥腹板在预应力集中荷载作用下等效压力矩形的选取方法，并基于平面应力的表达式提出了在三维情况下沿预应力轴线的横向应力计算方法。通过建立某预应力混凝土刚构桥0～3＃段实体有限元模型，分析施工过程中刚构桥混凝土腹板在不同等级预应力作用下的开裂情况。结果显示：有限元裂缝模拟与实桥腹板开裂范围一致，有限元应力分析结果下限值与推导的横向应力求解函数计算结果接近，变化趋势一致，印证了横向应力函数求解方法的正确性。