水平受荷钢筋混凝土桩刚度退化对桩身位移的影响分析

Impact Analysis of Stiffness Degradation of Laterally Loaded Reinforced Concrete Piles on Horizontal Displacement of Piles

对水平受荷钢筋混凝土桩,建立了可同时考虑桩身受弯开裂后刚度退化和土体水平抗力与位移非线性关系(p-y曲线)的弹性地基梁法,利用有限差分法实现求解。在不考虑土作用条件下,用上述方法分析某预应力高强度混凝土(PHC)管桩的简支梁抗弯试验成果,结果表明采用现行GB 50010—2010《混凝土结构设计规范》(2015年版)的抗弯刚度退化模型模拟弹性地基梁上钢筋混凝土构件的非线性特性合理可行。对某软土地基中PHC桩的水平荷载试验进行分析,表明考虑桩身刚度退化的影响分析比仅考虑土体水平抗力与位移非线性关系(p-y曲线)计算得到的桩顶水平荷载-位移关系与试验结果更为接近,刚度退化对桩身水平位移影响较大。因此,该方法在钢筋混凝土桩基水平载荷试验的全过程分析、桩基水平位移控制等设计中有应用价值。

A calculation method taking laterally loaded piles as beams on elastic foundation was established,which could consider degradation of bending stiffness of piles after flexural cracking and the non-linear relation between soil resistance and displacement simultaneously.Then,the solution was achieved by the finite difference method.Regardless of the impact of soil,a bending test of a PHC pile as a simple supported beam was simulated.The results indicated that it was reasonable and feasible to simulate nonlinear characteristics of concrete beams on elastic foundation adopting the stiffness degradation model suggested by GB 50010-2010 Code for Design of Concrete Structures(revised in 2015).Further,a laterally loading test of a PHC pile in soft clayey soil was analyzed.It is shown that the curve between horizontal loads at pile heads and displacements considering stiffness degradation of piles was closer to the test results compared with that one only considering the non-linear relation between soil resistance and displacement.The impact of stiffness degradation on laterally loaded reinforced concrete piles was more significant.Therefore,the analysis method was valuable for analyzing laterally loaded test of piles and designing deflection-controlled reinforced concrete piles.