预应力混凝土变截面箱梁桥在施工和运营过程中,跨中底板较易出现纵向裂缝.以某预应力混凝土刚构箱梁桥为研究对象,运用平面杆系结构与空间局部实体结构联合分析的方式,对箱梁桥跨中底板合龙束径向力的横向效应进行分析研究.结果表明,合龙段底板出现纵向裂缝主要是由预应力钢束产生径向力的横向效应引起的.针对底板纵向裂缝提出相应的防治措施并进行有限元模拟分析,与实桥的现场荷载试验相对照,验证了加固措施对箱梁底板横向受力有较明显的改善作用.%During the construction and operation of the prestressed concrete variable cross-section box girder bridge,it is easy to appear the longitudinal cracks in the midspan slab.Taking a prestressed concrete rigid frame box girder bridge as the research object and using the combination analysis of plane bar structure and space local entity structure,the transverse effect of the radial forces in closure tendon of the box girder bridge was analyzed and studied.The results indicate that the longitudinal cracks at the bottom of the closure section,are caused by the transverse effect of radial forces produced by the prestressed tendon.The corresponding prevention measures were put forward according to the vertical cracks in the slab,and the finite element simulation analysis was carried out.Compared with the load test results of the actual bridge,it is verified that the strengthening measures have obvious improvement effect on the transverse stress of the slab of the box girder.
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