内配型钢矩形钢管混凝土轴压短柱生命周期内的力学性能

Mechanical Behavior of Rectangular Concrete-filled Steel Tubular Stub Columns with Encased Profiled Steel Subjected to Axial Load in Life Cycle

为了研究内配型钢矩形钢管混凝土轴压短柱在生命周期内的受力机理,利用有限元软件ABAQUS建立该类短柱的计算模型,并与已有的相关试验结果进行对比。模型中将钢管初应力和长期荷载作为生命周期内的主要因素进行考虑,分析了内配型钢矩形钢管混凝土轴压短柱生命周期内的荷载-变形全过程曲线、跨中截面各部件纵向应力分布和钢材与混凝土之间的相互作用力;考察了初应力系数、长期荷载比和含钢率对构件承载力和变形的影响规律。结果表明:考虑钢管初应力和长期荷载作用的内配型钢矩形钢管混凝土轴压短柱极限承载力与一次加载情况下相比变化不明显,但极限承载力对应的纵向应变增长84.2%;在长期持荷阶段,核心混凝土发生卸载现象,其承担的荷载下降了30%左右,再加载阶段又继续承载;钢管与混凝土之间的接触应力在中截面处最大,沿构件长度方向逐渐向两端减小;随着钢管含钢率增大,构件极限承载力增大,变形减小,而型钢含钢率对构件变形影响较小;随着初应力系数和长期荷载比的增大,构件纵向变形增大。

In order to study the life cycle force mechanism of rectangular concrete-filled steel tubular(CFST) axial compressive stub columns with encased profiled steel, the finite element software ABAQUS was used to establish the calculation models and the models were compared with the relevant test results. The main influence factors such as initial stress of steel tube and long-term load were considered in the life cycle. The whole process load-deformation curves in life cycle, the longitudinal stress distribution of components in midspan section and the interaction between steel and concrete of rectangular concrete-filled steel tubular axial compressive stub columns with encased profiled steel were analyzed. Furthermore, the influences of initial stress coefficient, long-term load ratio and steel ratio on the bearing capacity and deformation of the component were also investigated. The results show that the ultimate bearing capacity of rectangular CFST axial compressive stub columns with encased profiled steel with the initial stress of steel tube and long-term load does not change significantly compared with the once loading, but the longitudinal strain corresponding to the ultimate bearing capacity increases by 84.2%. During the long-term sustained stage, the core concrete is unloading and the bear capacity of concrete decreases by about 30%, but it continues to bear in the reloading stage. The maximum contact stress between steel tube and concrete appears at the middle section and the contact stress decreases gradually along the length of the member. With the increase of steel ratio of steel tube, the ultimate bearing capacity of the component increases and the deformation decreases, while the steel ratio of profiled steel has little effect on the deformation of the component. Finally, with the increase of the initial stress coefficient and the long-term load ratio, the longitudinal deformation of specimens increases.