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通过4根低含钢率钢管混凝土圆柱的承载力试验,研究在不同荷载作用下4根圆柱的力学性能,对比钢管膨胀混凝土圆柱与普通钢管混凝土圆柱弹性泊松比的差异性,并探讨国内外钢管混凝土圆柱轴压极限承载力计算方法对低含钢率的适用性。试验研究表明:膨胀剂对钢管混凝土圆柱的轴压极限承载力影响不大;低含钢率钢管混凝土圆柱在各级荷载作用下表现出弹性、弹塑性和塑性三个工作阶段,且钢管膨胀混凝土圆柱与普通钢管混凝土圆柱横、纵向应变突变值相差较大;掺合膨胀剂的钢管混凝土圆柱在弹性阶段加载初期,泊松比接近于混凝土弹性泊松比,普通钢管混凝土圆柱在弹性阶段加载初期,泊松比接近于钢管的弹性泊松比。同时,依据钢管混凝土圆柱的破坏机理,分两种情况提出钢管混凝土圆柱轴压极限承载力的计算方法,经检验,该方法计算效果较好。
Through the four bearing capacity tests of concrete-filled steel tubular columns with low steel content, the mechanical properties of four cylinders subjected to different loads are studied, and the differences of elastic Poisson's ratio between concrete-filled steel tubular columns and ordinary concrete filled steel tubular columns are compared. Applicability of the calculation method of ultimate compressive bearing capacity of concrete filled steel tubular columns to low steel content. Experimental results show that the expansion agent has little effect on the ultimate bearing capacity of CFST columns. The CFST columns with low steel ratio show three stages of elasticity, elasto-plasticity and plasticity under various loads, The column and the concrete filled steel tubular column vary greatly in transverse and longitudinal strain change values. In the early stage of elastic loading, the concrete-filled steel tubular column with expansion agent is close to the Poisson's ratio of concrete elasticity. Poisson's ratio is close to the elastic Poisson's ratio of the steel pipe. At the same time, according to the failure mechanism of CFST column, the calculation method of axial compressive ultimate bearing capacity of CFST cylindrical column is put forward in two cases. The calculated results are good.