空腹式型钢混凝土L形柱压弯剪扭抗震性能试验研究

为研究空腹式型钢混凝土L形柱压弯剪扭滞回性能，以扭弯比、肢高肢厚比为变化参数，设计6个试件进行恒定轴压下的低周反复弯-剪-扭加载试验。通过试验观察了试件的受力破坏过程，获取了试件的扭矩-扭转角、弯矩-位移滞回曲线，分析了试件的破坏形态、承载能力、刚度退化、延性及耗能能力等抗震性能指标。结果表明：随着扭弯比的增大，L形柱的破坏形态表现为弯曲破坏、弯剪破坏及弯扭破坏；L形柱的扭矩-扭转角滞回曲线中部捏拢，形成滑移平台，峰值荷载后有明显的荷载“跌落”现象；弯矩-位移滞回曲线相对饱满，L形柱的受弯性能优于受扭性能。压弯剪扭复合作用下空腹式型钢混凝土L形柱的位移延性系数小于3，不能满足GB 50011—2010《建筑抗震设计规范》要求。

Experimental study on seismic behavior of steel truss reinforced concrete L-shaped columns under combined torsion and bending moment

In order to reveal the seismic behavior of steel truss reinforced concrete L-shaped columns under constant axial compression and cycled flexure-shear-torsion load, six specimens, considering two parameters, i.e. the ratio of torsion to flexure and the ratio of section height to section thickness, were prepared for the experiment. In this study, the failure process, torsion-angle hysteresis curves, moment-displacement hysteresis curves were obtained. The seismic behavior of specimens such as the failure patterns, bearing capacity, rigidity degradation, ductility and energy dissipation were analyzed. The experimental research indicates that the major failures of the specimens are flexure failure, flexure-shear failure and flexure-torsion failure with the ratio of torsion to flexure increasing. The torsion-angle hysteresis curves exhibits pinching effect in the middle, forms slip platform, and the phenomenon of ‘load drop’ occurs after the peak load. The moment-displacement hysteresis curves are plump, which shows that the flexure capacity of the specimen is better than the torsional capacity. The displacement ductility factor of steel truss reinforced concrete L-shaped columns under combined torsion is less than 3，which is unsatisfied with the request of GB 50011—2010 ‘Code for seismic design of buildings’.