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为研究钢管混凝土短柱在剪切和扭转复合作用下的受力性能,开展了10个钢管混凝土短柱试件在纯扭、弯-剪和弯-剪-扭荷载作用下的拟静力往复加载及单调加载试验,得到了钢管混凝土短柱的荷载-变形曲线和钢管应变分布规律。试验结果表明:钢管混凝土短柱具有良好的承载能力和塑性性能;在纯扭作用下,圆形钢管混凝土短柱在往复扭转荷载作用下钢管发生低周疲劳破坏;方形钢管混凝土短柱在单调及往复扭转荷载作用下钢管面外发生斜向局部屈曲;纯扭往复荷载作用下的钢管混凝土柱的荷载-变形骨架曲线与单调加载下基本一致;在弯-剪及弯-剪-扭复合荷载作用下,在进入塑性工作阶段前截面的轴向变形基本满足“平截面假定”;在弯-剪-扭耦合荷载作用下,短柱的破坏模式取决于弯扭比,在弯扭比较大(为1.90)时,其类似于弯剪破坏,在弯扭比较小(为0.96)时,其类似于扭转破坏。在有限元模拟及大量参数分析的基础上,得到了钢管混凝土短柱的弯-剪-扭承载力相关方程,承载力计算结果与有限元分析结果吻合较好。
In order to study the mechanical behavior of short concrete filled steel tubular columns under shear and torsional loads, ten pseudo-static reciprocating tests of ten concrete-filled steel tubular short columns under torsion, bending-shear and bending-shear-torsional loads Load and monotonic loading test, the load-deformation curve and the strain distribution of steel tube short columns are obtained. The experimental results show that the short concrete filled steel tubular columns have good bearing capacity and plasticity. Under the action of pure torsion, the short cyclic fatigue failure of the circular steel tubular short columns under cyclic and reversed torsional loads, The buckling-buckling of the concrete-filled steel tubular column under the action of pure torsional reciprocating load is basically the same with that under monotonic loading. Under the action of bending-shear and bending-shear-torsional composite load , The axial deformation of the cross section before the plastic working phase basically meets the assumption of “flat section assumption ”; under the bending-shear-torsional coupling load, the failure mode of the short column depends on the ratio of bending to torsion, (1.90), it is similar to buckling failure, which is similar to torsional failure when the bending-torsion ratio is small (0.96). On the basis of finite element simulation and a large number of parameters analysis, the formulas of bending-shear-torsion bearing capacity of concrete filled steel tubular short columns are obtained. The calculation results of the bearing capacity coincide well with those of the finite element analysis.