长期荷载作用下矩形钢管混凝土轴压短柱力学性能

Behavior of Rectangular CFST Axial Compressive Stub Column under Long-term Loading

基于AC I209(1992)的徐变和收缩计算模型,在合理考虑长期荷载作用下钢管和核心混凝土应力-应变关系模型的基础上,利用ABAQUS软件建立了长期荷载作用下的矩形钢管混凝土轴压构件的数值分析模型。基于此理论模型,对长期荷载作用下矩形钢管混凝土短柱的受力特性进行了分析,对比了考虑长期荷载效应与否时钢管对混凝土的约束力、核心混凝土应力场等的影响。结果表明:长期荷载作用下矩形钢管混凝土的纵向应变随着截面高宽比β的增大而不断减小,外包钢管对混凝土角部横向约束力在高度L/2处最大,然后向构件两端逐渐减小。由于核心混凝土的徐变与收缩,构件截面出现了应力重分布。

A numerical model was developed using ABAQUS to simulate the behavior of rectangular concrete-filled steel tubular（CFST） axial compressive members under long-term loading based on the concrete creep and shrinkage model proposed by ACI209（1992） and rational stress-strain relationship of CFST members under long-term loading.The mechanical performance of the rectangular CFST stub columns under long-term loading were analyzed based on the model.The confined effects of core concrete by the steel tube and the stress distribution of core concrete with and without long-term loading were investigated by comparison.It is shown that（1） The longitudinal concrete strain of rectangular CFST stub columns with long-term loads decreases with the incremental cross-sectional aspect ratio β.The transverse confined effect of concrete at the corner reaches its maximum at the height of L/2,and then decreases gradually to both ends.（2） The stress redistribution appeared in the section due to the creep and shrinkage of core concrete.