压-扭荷载下CFRP-方形钢管混凝土的力学性能研究

以轴压比、CFRP层数和混凝土立方体抗压强度等为参数，开展了压-扭荷载下CFRP-方形钢管混凝土(S-CF-CFRP-ST)的静力性能试验，得到了试件的扭矩-转角(T-θ)曲线、扭矩-应变(T-ε)曲线和破坏模态。试验结果表明，钢管与CFRP可协同工作；同一点的45°方向应变始终为负，横向应变始终为正，纵向应变根据轴压比的变化为正或为负；小轴压比CFRP-方形钢管混凝土试件在压-扭荷载下发生延性破坏。采用ABAQUS模拟试件扭矩-转角曲线和变形模态并开展受力全过程分析，模拟和分析结果与试验现象和结果吻合良好。参数分析的结果表明，提高混凝土强度、钢材屈服强度、含钢率和横向CFRP层数可提高构件的抗扭承载力；通过对试件扭矩-转角曲线的大量分析，导出了CFRP-方形钢管混凝土的压-扭承载力相关方程。

Study on mechanical property of concrete-filled square CFRP-steel #br# tube under combined loading of compression and torsion

With the axial compression ratio, the number of CFRP layers and compressive strength of concrete taken as the factors, the static performance tests of square concrete-filled CFRP-steel tube(S-CF-CFRP-ST) specimens under the combined actions of compression and torsion were carried out. The torque-rotation angle(T-θ) curve, torque-strain(T-ε) curve and failure mode of the specimens were obtained. The results show that the steel tube and CFRP can work cooperatively. At the same point, the strain in the direction of 45°is always negative, the transverse strain is always positive, and the longitudinal strain is either positive or negative depending on the change of axial compression ratio. Square concrete-filled CFRP-steel tubular specimens with small axial compression ratio fail with the ductile behavior. ABAQUS was used to simulate the torque-rotation angle curve and deformation mode of the specimens for the whole loading process.Based on the results, it is found that the simulation results agree well with the experimental results. Additionally, the parametric analyses show that the torsional load carrying capacity of the members can be improved by increasing the strength of concrete, the yield strength of steel, the steel ratio and the number of transverse CFRP layers. Through a large number of analyses on the torque-rotation angle curves of the specimens, the equations for calculating the compressive-torsional load carrying capacity of the members are then derived.