钢管约束再生混凝土的受力机理及强度计算

Mechanical performance and ultimate bearing capacity calculation of steel tube confined recycled coarse aggregate concrete

为揭示钢管约束再生混凝土的受力机理,设计33个钢管再生混凝土试件进行轴心受压加载试验,其中圆钢管试件22个、方钢管试件11个。试验考虑再生粗骨料取代率、截面形式和套箍指标3个变化参数。试验观察试件的受力破坏全过程,获取荷载-位移曲线、峰值应力等重要参数。研究结果表明:圆钢管再生混凝土试件的破坏形态表现为腰鼓状斜剪压破坏,而方钢管再生混凝土则呈现斜压破坏;试件受力破坏全过程曲线均经历峰值点、下降段、再次上升段等历程,各试件的峰值应力和峰值应变与普通再生混凝土相比有明显提高,且圆钢管试件较方钢管提高更为显著。取代率对钢管再生混凝土的破坏机理有影响但不明显。基于试验实测数据,分别采用全过程分析法和极限分析法对钢管约束再生混凝土的极限承载力进行理论分析,并提出应力-应变全过程曲线的数学表达式和极限强度计算公式,理论计算结果与试验实测结果吻合良好,研究结果可供钢管约束再生混凝土的科学研究和工程应用参考。

To study the bearing capacity of recycled aggregate concrete-filled steel tube （RACFST） short columns under axial loading, 22 recycled aggregate concrete-filled circular steel tube （RACFCST） short columns and 11 recycled aggregate concrete-filled square steel tube （RACFSST） short columns are designed for axial compression test, with the variable parameters of recycled coarse aggregate replacement percentage, section type and confinement index considered. Test results indicate that the circular steel tube and square steel tube has the waist-shaped diagonal shear compression and diagonal shear failure pattern, respectively, the stress-strain curves of all specimens are basically similar. Compared with recycled aggregate concrete, the peak strain and peak stress of RACFST were improved greatly, especially for RACFCST. Based on the entire process analysis and limit analysis, the bearing capacity of RACFST is analyzed, and the stress-strain relationship and ultimate bearing capacity calculation formula of RACFST short columns are proposed. By comparing the calculation results with test results, a good agreement may be obtained. The conclusions can be helpful for the scientific study and engineering application of RACFST short columns.