倾斜荷载下基桩P-Δ效应等效弯矩有限元迭代法

Calculation for P-Δ effect of pile under inclined loads by equivalent-moment finite element-iterative method

假定桩身位移为三次幂函数,结合倾斜偏心荷载下单桩受力微分方程确定的桩身弯矩、剪力与桩身水平位移关系,引入等效附加弯矩概念,提出了基桩P-Δ效应的等效弯矩有限元迭代法,编制了Matlab分析程序,并结合算例对成层地基中倾斜偏心荷载、桩自重、水平分布荷载、竖向分布荷载和竖向荷载综合作用下基桩内力位移进行了分析。结果表明:等效弯矩有限元迭代法用于倾斜荷载下基桩P-Δ效应计算分析是有效的;当墩身较高时,墩身倾斜、墩顶偏心弯矩、水平力等对基桩产生的P-Δ效应显著。

It is assumed that horizontal displacement of pile has a longitudinally cubic power function,and equivalent-moment finite element-iterative method which can analyze the P-Δ effect of piles under inclined and eccentric loads,is derived in the paper.And matlab process of equivalent-moment finite element-iterative method is edited.Case analysis is done in the paper for displacement and stress calculation of pile under inclined and eccentric loads,moment,pile gravity,horizontal distributed loads,vertical distributed loads,scattering vertical forces and soil-pile friction.Finally conclusions are drawn as follows：（1） equivalent-moment finite element-iterative method is proved to be a effective method for P-Δ effect analysis of piles under complex loads;（2） P-Δ effect is notable while piers are high.