圆中空夹层钢管混凝土压扭构件试验研究

以轴压比和长细比为主要参数设计了7根圆中空夹层钢管混凝土试件,为了便于对比分析,同时设计了2根圆实心钢管混凝土试件,对其在压扭复合受力状态下的力学性能进行了试验研究。对试验现象和试验结果进行了描述与分析,结果表明:圆中空夹层钢管混凝土压扭构件的扭矩-转角全过程曲线未出现下降段,试件表现出一定的后期承载潜力,具有较好的塑性和延性性能;钢管对混凝土的约束效应在加载后期更为显著;轴压比、长细比和空心率对压扭试件的初始刚度影响不大,但轴压比和长细比对试件的抗扭承载力有一定影响。最后,采用压扭构件承载力相关方程对圆中空夹层钢管混凝土压扭构件的抗扭承载力进行了计算,计算结果与试验结果基本接近且总体偏于安全,可为工程设计提供参考。

Experimental Study of Concrete-filled Double Skin Steel Tube Members (CHS Inner and CHS Outer) Subjected to Compression and Torsion

7 concret-filled double skin steel tube (CFDST) specimens were designed by taking the axial compression ratio and slenderness ratio as main parameters. At the same time, 2 concrete-filled steel tube (CFST) specimens were also designed for comparative analysis. An experimental study was carried out to investigate CFDST mechanical performances under axial compression and torsion composite loading state. Experimental phenomenon and results are described and analyzed respectively in this paper. Results show that in whole loading process, there is no descending segment on torque versus angle curve of the CFDST members subjected to compression and torsion, and CFDST exhibits some potential late bearing capacity due to its good plasticity and ductility. The confinement effect of steel tube on concrete is more significant on the late loading stage. The axial compression ratio, slenderness ratio and hollow ratio have little effect on initial rotational stiffness of specimens, while the axial compression ratio and slenderness ratio have certain effect on the torsional capacity. Finally, the bearing capacity correlation equation for members subjected to compression and torsion was adopted to calculate the torsion capacity of CFDST member. Calculation results are basically close to test results and are somewhat overall on the safe side. The correlation equation can be used as a reference for project design.