考虑桩身钢筋混凝土非线性的单桩水平响应分析

Computation method for the response of laterally loaded reinforced-concrete piles

为评估地震条件下建筑和桥梁桩基础水平承载性能,给出了考虑桩身钢筋混凝土非线性的单桩水平响应的计算方法。该方法是基于非线性Winkler地基梁,利用应变楔形体模型计算地基反应模量,桩身钢筋混凝土非线性是通过将桩截面划分成多个纤维单元,并将钢筋纤维单元和混凝土纤维单元赋予不同的非线性应力应变关系来实现的。结果表明:计算出的桩头挠度及挠度分布与实测值吻合较好,且能够反映钢筋混凝土桩抗弯刚度随着水平荷载增大的变化趋势,在钢筋混凝土桩初始加载阶段,桩截面上拉应力和压应力呈对称分布,随着水平荷载的增大,受拉侧混凝土开裂,中性轴向受压侧移动。

To evaluate the horizontal bearing capacity of a pile foundation subjected to large lateral load due to earthquake loading,a computation method for the response of laterally loaded reinforced-concrete（ RC） piles was proposed in this study. The computation method was based on the theory of a nonlinear elastic foundation beam,in which the subgrade reaction modulus was calculated by a modified strain wedge model. The material nonlinearity of RC piles was also considered by assigning nonlinear stress-strain relationship to the fibers into which each plane section of RC pile was divided. The results show that： 1） the predicted load-deflection curves and deflection profiles accord well with the measurements; 2） the distribution of compressive and tensile stress is symmetrical on the cross-section of the pile until the concrete crack occurs,and after the crack occurs,the neutral axis of the pile cross-section moves forward to the side with compressive stress. It can be concluded that the proposed method can provide an efficient and effective way for laterally loaded reinforced-concrete piles.