改进的组合式L形钢管混凝土长柱轴压性能非线性分析

Nonlinear Behavior of Improved Composite L-shaped Concrete-filled Steel Tubular Long Columns Subjected to Axial Compression Load

采用有限元软件ABAQUS对改进的组合式L形钢管混凝土长柱轴压性能进行了非线性分析,主要分析了改进的组合式L形钢管混凝土长柱破坏形态、荷载-轴向位移关系曲线、荷载-侧向挠度关系曲线以及钢管、支撑钢板、核心混凝土之间的相互作用.研究结果表明:试件破坏形态主要分为弯曲破坏和强度破坏.钢管厚度及长细比对试件荷载-轴向位移关系曲线影响较大;混凝土强度及支撑钢板设置对试件荷载-轴向位移关系曲线影响较小;长细比、支撑钢板设置及钢管厚度对试件荷载-侧向挠度关系曲线影响较大.从加载开始至75%峰值荷载时,钢管和核心混凝土承担轴压荷载比例变化不大;达到峰值荷载时,钢管承担轴压荷载比例有所增加,核心混凝土承担轴压荷载比例有所减少.相较于未设置支撑钢板的试件,设置支撑钢板的试件各面接触压力更加均匀.在矩形钢管中设置支撑钢板能够提高钢管对核心混凝土的约束作用.轴压稳定承载力计算式(1)、式(11)的理论计算值均小于有限元计算值.

The finite element software ABAQUS was used to analyze the nonlinear behavior of improved composite L-shaped concrete-filled steel tubular long columns subjected to axial compression load,including the failure modes,load-axial displacement curves,load-lateral deflection curves and the interaction among steel tube,support steel plate and core concrete.The results show that：the failure modes of specimens are mainly divided into bending failure and strength failure.The thickness of steel tube and the slenderness ratio have a greater influence on the load-axial displacement curve of the specimen and the influence of the concrete strength and the support steel plate on the load-axial displacement curve is smaller.The slenderness ratio,support steel plate and steel tube thickness has great influence on the load-lateral deflection curve.From the beginning of loading to 75% peak load,the axial load ratio of steel tube and core concrete changes little.To 100% peak load,the axial load ratio of the steel tube increases,the axial load ratio of the core concrete decreases.Compared with the specimens without support steel plate,the contact pressure of the specimens with support steel plate is more uniform.The support steel plate in the rectangular steel tube can improve the restraint effect of the steel tube on the core concrete.The formulas（1）and（11）for calculating the axial compressive stability bearing capacity are less than those calculated by the finite element method.