钢管混凝土复合短柱轴压性能试验研究

Experimental study on compressive property of concrete-filled steel tubular hybrid stub columns

钢管混凝土复合柱由钢管混凝土柱肢和钢筋混凝土联接板组成。以柱肢钢管壁厚和联接板厚度为试验参数,对7个复合短柱试件进行轴压性能试验研究,同时进行了与复合柱试件组成相对应的4个钢管混凝土柱构件和3个钢筋混凝土板构件的轴压试验。研究复合短柱在轴压荷载作用下的破坏模式和荷载-位移曲线,对比分析试件与对应构件的荷载-应变曲线,研究柱肢钢管壁厚和联接板厚度对复合短柱轴压承载力的影响。试验结果表明:轴压复合短柱受力全过程分为弹性阶段、弹塑性阶段和塑性发展阶段;轴压复合短柱的破坏特征为钢筋混凝土联接板混凝土压碎,此时钢管混凝土柱肢的受力状态与对应的钢管混凝土构件的受力状态不同,钢管混凝土柱肢并没有充分发挥其自身的承载能力;在复合短柱的轴压承载力计算中应引入柱肢承载力折减系数,该系数与柱肢套箍系数相关;通过对现有的钢管混凝土轴压短柱的试验数据进行回归分析,拟合得到柱肢承载力折减系数的经验计算公式;按照建议方法计算得到的复合短柱的轴压承载力与试验结果吻合良好。

Concrete-filled steel tubular（ CFST） hybrid columns are composed of CFST members and connected by reinforced concrete（ RC） plates. Experimental study on seven axially-loaded CFST hybrid stub columns with different wall thickness of steel tube and thickness of RC plate was carried out. The failure modes,compression deformation,and strain process were obtained. The effect of wall thickness of steel tube and thickness of RC plate on the ultimate load-carrying capacity was also analyzed. The test results show that the responses of CFST hybrid stub columns can be divided into the elastic state,elasto-plastic stage,plastic development stage. The failure of an axially loaded CFST hybrid stub column is due to the crushing of RC plate,while the CFST member does not reach its ultimate resistance.A reduction coefficient K,related to the confinement coefficient,is introduced to account for the contribution of CFST members to the ultimate load-carrying capacity of the CFST hybrid stub columns. Based on the collected existing test date of axially loaded CFST hybrid stub columns,an empirical calculation formula for the reduction coefficient K is presented. Comparison study indicates that the predicted load-carrying capacity of axially-loaded CFST hybrid stub column by the calculation methods presented in this paper are close to the test results.