不同壁厚钢管再生混凝土短柱轴压力学性能研究

Experimental Study of Recycled Aggregate Concrete-Filled Steel Tube Short Column with Different Wall-Thickness under Axial Compression

为了明确100%再生骨料取代率下钢管壁厚对钢管再生混凝土短柱(RACFST)受力性能的影响规律,开展了试验研究.分别设计了10根圆形截面的钢管混凝土试件(CFST)和RACFST试件并进行轴压试验.根据试验结果进行了对比分析,研究了钢管壁厚对破坏模式、荷载位移和荷载应变曲线、刚度、断裂韧性、延性、离散性等关键指标的影响机理,同时对承载力计算方法进行了探讨.结果表明:壁厚的增加能有效改善RACFST的力学性能并降低其性能的离散性;随着单位含钢率的增加,CFST和RACFST的承载效率趋于劣化;随着钢管壁厚的减少,规范公式承载力预测可靠度降低.最终,推荐圆形截面RACFST承载力计算公式,并验证了其准确性和稳定性;推荐套箍系数合理的取值范围为1.22~1.41.

To make clear the effect of the wall-thickness of steel tube on the mechanical behavior of Recycled Aggregate Concrete-Filled Steel Tube(RACFST)short columns with 100%recycled coarse aggregate replacement ratio,experimental studies were performed.10 circular Concrete-Filled Steel Tube(CFST)and RACFST specimens,respectively,were fabricated and tested under axial compression.The influencing mechanism of wallthickness on the failure mode,load-displacement and load-strain curves,stiffness,fracture toughness,ductility and performance-discreteness were analyzed,and the strength predicting method was discussed as well.The results show that the increase of wall-thickness can effectively improve the mechanical performance of RACFST and relieves the performance-discreteness;the load-carrying capacity of CFST and RACFST tends to decrease with the increase of the steel ratio,and the strength predicting equation proposed by code becomes unstable with the decrease of wall-thickness.As a result,an equation for predicting the ultimate load bearing capacity of RACFST was recommended,and its accuracy and reliability were validated;the reasonable range of the confinement coefficient for RACFST was recommend as 1.22~1.41.