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某市市民服务中心为135.6 m长不设缝框架-核心筒结构建筑。为抵消或减小温差应力、混凝土收缩,特别是减小4个核心筒对温差变形与混凝土收缩变形的约束作用,避免楼盖产生构造裂缝,除采取在相关部位设置后浇带的措施外,在房屋顶层沿长向的框架梁与次梁内布置并张拉了直线形预应力筋。张拉时,一根框架梁的预应力筋出现了拉断事故。给出了考虑约束影响的温差及混凝土收缩应力,计算了拉断前后预应力效应,分析了预应力筋拉断对结构的不利影响,提出了相关处理措施。可供需控制构造裂缝的同类工程建设时参考。
A city civic service center is 135.6 m long without seam frame - core tube structure building. To offset or reduce temperature stress, concrete shrinkage, in particular, to reduce the four core tube temperature difference between the deformation and shrinkage of concrete constraints, to avoid structural cracks in the floor, in addition to take the relevant parts of the post-pouring zone measures, Straight prestressing tendons are placed and tensioned in the longitudinal girders and subbeams along the length of the roof. Tension, a frame beam prestressed tendons appeared pulled off accident. The temperature difference and the shrinkage stress of the concrete considering the influence of the constraint are given. The prestressing effect before and after the breakage is calculated, the adverse effect of the prestressing tendon pullout on the structure is analyzed, and the relevant treatment measures are put forward. For control of structural cracks for the construction of similar projects reference.