框架结构-基础-地基共同作用的三维有限元分析

3D finite element analysis of interaction of frame structure-foundation-soil

基于上部结构-基础-地基共同作用的概念,采用现行规范对某三层框架结构的基础进行设计,运用ABAQUS有限元软件建立起由该框架结构、基础和地基构成一体的三维实体有限元模型。基础和地基土的相互作用按库仑摩擦接触模拟,并以邓肯-张模型模拟地基土以反映其实际的非线性变形特性,分析三者共同作用下,柱下独立基础的沉降差异以及框架结构梁、柱和基础的实际内力分布,指出上部结构实际内力与常规方法设计计算内力的差异。从减小基础不均匀沉降的角度出发,对原基础进行2次尺寸修改,重新进行整体有限元分析,获得该框架结构的最优基础设计尺寸,以使上部结构在设计荷载下的实际内力与常规方法设计计算内力基本一致,且同时准确获得独立基础的内力分布,方便基础的冲切和弯曲破坏验算及配筋设计。

Foundation design of a 3 - storey frame structure was introduced in this paper based on the current norm. Then, based on the conceptual design of the interaction of superstructure - foundation - soil, a 3 - storey 3D solid finite element model composed by frame structure, foundation and soil was established using the finite element program, i.e. , ABAQUS. Thereinto, the interaction of soil and foundation was simulated utilizing coulomb friction contact, and Duncan - Chang＇ s model was adopted to simulate nonlinear deformation behaviors of the soils. The settlement differences of isolated foundations and internal force distributions of frame structure beams, columns and foundation were analyzed under the effect of interaction, from which one can notice that the differences between the actual internal forces of the superstructure and design internal forces based on conventional method. From the perspective of diminishing the differential settlement of foundations, the original foundation sizes were modified twice and finite element analyses of the whole models was redone, by which the optimal foundation sizes of the frame structure were obtained so that the actual internal forces of the superstructure under design load are in accordance with the design internal forces obtained by the conventional method. Meanwhile, the internal force distribution of the isolated foundations was derived accurately and this is beneficial to the checking calculations of punching and bending failures as well as reinforcement design.