带环向脱空缺陷的钢管混凝土构件在压弯扭复合#br# 受力作用下的滞回性能研究

为研究环向脱空缺陷对钢管混凝土试件在压弯扭复合受力作用下抗震性能的影响，进行了12个钢管混凝土试件（包括8个带缺陷试件、2个无脱空试件以及2个空钢管对比试件）在恒定轴压力和反复弯扭耦合荷载作用下的滞回性能试验。试验主要参数为：脱空率、弯扭比和轴压比。基于试验结果考察了带脱空缺陷的钢管混凝土试件在压弯扭复合受力作用下的破坏模态，并分析了脱空对试件滞回曲线、骨架曲线、刚度和耗能等力学指标的影响规律，结果表明：环向脱空缺陷的存在会改变钢管混凝土构件的破坏模态，并使试件的承载力、刚度和耗能能力有不同程度的降低。同时，建立钢管混凝土压弯扭构件的有限元模型，分析环向脱空对构件承载力系数，以及钢管与核心混凝土接触时刻的影响规律，在此基础上提出相关工程建议。

Cyclic behaviour of concrete-filled steel tubular (CFST) members with circumferential gap under combined compression-bending-torsion load

 In order to study the effects of circumferential gap on the seismic behaviour of concrete-filled steel tubular (CFST) members subjected to combined compression-bending-torsion load, a total of 12 specimens including 8 CFST specimens with circumferential gap, 2 CFST specimens without gap and 2 hollow steel sections, were tested under constant axial compressive load and cyclically combined actions of bending and torsion. The testing parameters included gap ratio, bending-torsion ratio and axial load level. Based on the test results, the failure mode of the CFST with circumferential gap was investigated, and the influences of gap on the hysteretic curve, skeleton curve, stiffness and energy dissipation capacity were experimentally analyzed. It was evident that the existence of circumferential gap could change the failure mode of a CFST specimen, and decrease its ultimate strength, stiffness and dissipated energy. Meanwhile, a finite element model was also established, and the effects of circumferential gap on the strength index and the contact time between outer steel tube and core concrete were investigated by the numerical model. According to the experimental and numerical studies, some suggestions were proposed for the practical CFST structures.