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进行了5个对照组,总计8个1∶5四桩承台冲切破坏的模型试验与有限元分析,试件均按空间桁架理论设计,配筋形式包括集中于桩顶区域布置纵筋,布置腹部水平钢筋网与配置型钢桁架。研究结果表明:承台冲切破坏的传力体系为带有主要单向压应力区域的混凝土作压杆,桩顶区域间的纵筋作拉杆的空间桁架;以我国现行规范与ACI 318-08规范中的临界截面应力法为代表的上限解法在传力机理方面存在理论欠缺;当承台与桩筏筏板的破坏形式为冲切破坏时,可依据空间桁架传力机理,合理布筋,创造出性能优良的新型结构。给出了与试验结果吻合良好的承台与桩筏筏板的开裂荷载公式。
Five control groups were set up, a total of eight model tests and finite element analysis of punching failure of four 1: 5 pile caps were carried out. The specimens were designed according to the spatial truss theory. Laying abdomen horizontal steel mesh and configuration steel truss. The results show that the force transfer system of the punching failure of the platform is the concrete with the main unidirectional compressive stress region and the longitudinal reinforcement between the top of the pile as the space truss of the tie rod. According to the current codes of our country and ACI 318-08 In the standard, the critical section stress method represented by the upper bound solution has a theoretical deficiency in the transmission mechanism. When the failure mode of the caps and raft rafts is punching and cutting failure, Create a new structure with excellent performance. The cracking load formula of the platform and the raft with the good agreement with the test results is given.