圆钢管自应力自密实混凝土短柱轴心受压性能研究

通过对18根圆钢管混凝土短柱进行轴心受压试验，研究初始自应力、钢管壁厚和混凝土强度对其破坏形态、荷载-位移曲线、承载力和变形能力等的影响。试验结果表明：初始自应力对圆钢管自应力自密实混凝土短柱的破坏形态影响不明显，在轴心荷载作用下，所有短柱均为剪切破坏；初始自应力可显著提高圆钢管自应力自密实混凝土短柱的轴压刚度和承载力，其中承载力提高幅度可达27.5%；初始自应力会导致圆钢管自应力自密实混凝土短柱的变形能力明显降低，极限位移和破坏位移大幅减小；钢管壁厚和混凝土强度对圆钢管自应力自密实混凝土短柱承载力的影响幅度受初始自应力的影响。最后，考虑初始自应力的影响，建立圆钢管自应力自密实混凝土短柱轴心受压承载力计算公式，计算结果与试验结果吻合较好。

Experimental study on self-stressing and self-compacting concrete-filled circular steel tube short columns subjected to axial compression

Eighteen specimens with different initial self-stresses, thicknesses of steel tube and concrete strengths were tested under axial compression. The failure mode, axial load-axial shortening curve, carrying capacity and deformability were investigated. The results indicated that the failure mode of the self-stressing and self-compacting concrete-filled steel tube columns was similar to that of the self-compacting concrete-filled steel tube columns. An obvious shear plane can be observed in all columns. The initial self-stress significantly increases the carrying capacity of the column but reduces its deformability. The carrying capacities of the self-stressing and self-compacting concrete-filled steel tube columns are 27.5% higher than those of the self-compacting concrete-filled steel tube column counterparts. The ultimate displacement and the failure displacement both decrease significantly due to the existing of self-stress. The influences of the thickness of steel tube and the concrete strength on the behavior of self-stressing and self-compacting concrete-filled steel tube columns are related to the self-stress to some extent. Based on the results, formulas were proposed to calculate the carrying capacity of self-stressing and self-compacting concrete-filled steel tube columns, and the predictions agreed well with the experimental results from this study and the literatures.