开孔钢板加劲的矩形钢管钢纤维高强混凝土柱轴压试验研究

为探明加劲肋类型、开孔钢板（PBL）开孔间距、钢纤维体积掺量、混凝土强度等级等对矩形钢管钢纤维高强混凝土（SFRHC）柱轴压破坏模式的影响规律，对10根柱进行了轴压性能试验，得到了其荷载-压缩变形曲线、位移延性系数、耗能指标和破坏模式。研究结果表明：与PBL加劲试件相比，钢板加劲试件和未加劲试件的位移延性系数分别降低11.9%和10.4%，耗能指标分别降低8.3%和5.6%， PBL加劲肋能有效加强钢管与核心混凝土的组合作用。掺入体积率为0.8%钢纤维的PBL加劲试件，其位移延性系数和耗能指标分别提高12.5%和42.3%，钢纤维体积率为0.8%~1.2%时，试件位移延性系数和耗能指标明显提高。加劲SFRHC柱为肋间管壁局部外鼓破坏，PBL加劲柱的破坏位置均位于PBL开孔处，未加劲SFRHC柱为管壁外鼓破坏，对应钢板屈曲处核心混凝土表现为压碎破坏，钢纤维被整体拔出；加劲SFRHC柱沿高度方向破坏位置明显下移，钢板加劲肋和PBL加劲肋均能有效分担轴向荷载。

Experimental study on steel fiber reinforcement high strength concrete-filled rectangular steel tubular column stiffened with perfobond strip under axial compression

Axial compression tests on ten column specimens were carried out to investigate the effects of a number of parameters on the failure modes of steel fiber reinforcement high strength concrete (SFRHC)-filled rectangular steel tubes. The parameters under investigation include the type of stiffeners, the interval of the holes of perfobond strips (PBL), the volume ratio of steel fiber, the concrete strength. The load-compression deformation curve, displacement ductility ratio, energy dissipation and failure mode were obtained for each specimen. The test results indicate that displacement ductility ratios of the specimen with plate stiffeners and that without stiffeners are 11.9% and 10.4% lower than the specimen with PBL stiffeners, respectively. The energy dissipation indexes of the specimen with plate stiffeners and that without stiffener are 8.3% and 5.6% lower than the specimen with PBL stiffeners, respectively. The PBL stiffener can improve the composite action between the outer steel tube and the concrete infill. The displacement ductility ratio and the energy dissipation are improved by 12.5% and 42.3%, respectively, when the volume ratio of steel fibers is 0.8%.When the volume ratio of steel fibers ranges from 0.8% to 1.2%, higher displacement ductility ratio and energy dissipation can be achieved. The failure modes of the specimens with PBL stiffeners or steel plate stiffeners are the outward local buckling of steel tube at locations between the stiffeners; such local buckling is located at the holes of PBL for the specimens with PBL stiffeners. For the specimens without stiffeners, the failure mode is the outward buckling of the steel tube. The buckling position of SFRHC-filled rectangular steel tube with stiffeners shifts downward along the tubes compared to that without stiffeners. Both plate stiffeners and PBL stiffeners can effectively take some loads. The failure of the concrete infill appears at the locations corresponding to the local buckling of the steel tube, in the form of concrete crushing with pullout of steel fibres.