外套钢管自密实混凝土加固钢筋混凝土圆形截面短柱轴压性能试验研究

提出外套钢管自密实混凝土加固钢筋混凝土柱的复合加固方法。通过11个加固钢筋混凝土圆形截面短柱试件（其中2个为增大截面加固柱试件、9个为复合加固柱试件）和2个未加固钢筋混凝土圆形截面短柱试件的轴压试验，对不同方法加固的钢筋混凝土圆形截面短柱承载力、刚度和延性进行研究，分析加载方式、含钢率、后浇自密实混凝土强度、界面处理方式等因素对复合加固柱轴压性能的影响。试验结果表明：复合加固柱试件的承载力和延性均优于未加固钢筋混凝土圆柱试件和增大截面加固柱试件。仅核心混凝土受压的试件承载力略大于全截面受压的试件；随着含钢率的增大，复合加固柱试件的承载力和延性提高显著；随着后浇自密实混凝土强度的提高，复合加固柱试件的承载力略有提高，但延性有所下降；界面处理方式对复合加固柱试件轴压性能影响不显著。在试验研究的基础上，提出复合加固钢筋混凝土圆形截面短柱的承载力计算式，得出的计算结果与试验结果吻合良好。

Experimental research on behavior of circular RC column strengthened with self-compacting concrete filled circular steel jacket under axial loading

A new composite strengthening method where the RC column was strengthened with self-compacting concrete filled circular steel jacket was presented. Mechanical properties of two RC columns, two RC columns strengthened by enlarging cross-section method and nine RC columns strengthened with self-compacting concrete filled circular steel jacket subjected to axial loading were investigated. The influences of loading mode, steel ratio, compressive strength of strengthening self-compacting concrete and interface bond on bearing capacity, stiffness and ductility of strengthened columns were analyzed. Test results show that the bearing capacity and ductility of the composite strengthened columns are significantly better than the columns strengthened by enlarging cross-section and the RC column. The load bearing capacity of composite strengthened columns with loading on only core concrete is slightly better than those with loading on full section. With the steel ratio increasing, composite strengthened columns show a significant increasing trend in the load bearing capacity and ductility. With the compressive strength of strengthening concrete increasing, composite strengthened columns show a slight increasing trend in the load bearing capacity but a decreasing trend in ductility. The mechanical property subjected to axial loading of composite strengthened columns is not affected by interface bond. Based on the results, a formula was proposed to calculate the load bearing capacity of the composite strengthened short columns. The calculating results agree with the experimental results well.