斜向受力十字形钢管混凝土柱抗震性能试验研究

为研究十字形钢管混凝土柱在斜向受力下的抗震性能，以加载角度(0°和45°)、混凝土强度等级(C50和C70)、轴压比(0、0.25和0.5)以及是否设置加劲肋为试验参数，进行了9根十字形钢管混凝土柱在往复荷载作用下的试验研究，获得了柱的破坏形态、水平荷载-位移滞回曲线、骨架曲线、延性、累积耗能、变形等特性，分析了不同参数对柱抗震性能的影响规律。并建立了十字形钢管混凝土柱的有限元模型，有限元分析结果与试验结果吻合良好。试验结果表明:十字形钢管混凝土柱具有较好的滞回性能，所有柱的位移延性系数均高于3.5；轴压比对十字形钢管混凝土柱的抗震性能影响较大，轴压比越大，柱承载力越低，刚度退化越快，延性和耗能能力也越差；随着混凝土强度的增加，柱承载力增加，轴压比较大时，混凝土强度越高，延性下降越明显；内部间断焊接加劲肋的柱比未设置加劲肋柱的承载力提高约8%，但延性和耗能能力提高不大；加载角度为45°柱的滞回性能稍优于0°的柱。

Experimental study on seismic behavior of cross-shaped concrete-filled steel tubular columns under diagonal cyclic loading

In order to study the seismic behavior of cross-shaped concrete-filled steel tubular (CFST) columns under diagonal loading, cyclic experiments on nine specimens were carried out. The main parameters were loading angle (0° and 45° ), concrete strength grade (C50 and C70), axial compression ratio (0, 0.25 and 0.5), presence or absence of stiffener. The hysteretic behavior such as failure mode, horizontal load-displacement hysteretic curve, skeleton curve, ductility and cumulative energy dissipation were obtained and the influences of different parameters were analyzed. A finite element model of cross-shaped CFST columns was developed. It’s found that the calculated results agree well with the test results. The test results show that the cross-shaped CFST columns have good hysteretic behavior and the displacement ductility coefficients of all specimens are greater than 3.5. The axial compression ratio has great influence on the hysteretic behavior of cross-shaped columns. Increasing axial compression ratio results in decreasing load bearing capacity, faster degradation of stiffness, weaker ductility and energy dissipation. With the increase of concrete strength, the load bearing capacity increases. Under the condition of great axial compression ratio, the ductility drops dramatically due to higher concrete strength. Compared with the specimens without stiffeners, the specimens with inner stiffeners welded intermittently exhibit about 8% higher load bearing capacity, slightly better ductility and energy dissipation. The specimens at 45° loading angle show slightly superior hysteretic behavior than the specimens at 0° loading angle.