带槽口缺陷的圆钢管短柱轴压性能试验

本文对带有在圆钢管切割工艺中所产生的槽口缺陷的圆钢管短柱进行了系列力学性能试验研究。通过对144根圆钢管短柱进行筛选,挑选出合计51根带槽口缺陷的圆钢管短柱,并对该51根带槽口缺陷的圆钢管短柱试件进行轴压性能试验研究。分析了槽口缺陷类型、槽口缺陷高度以及钢管壁厚对试件破坏模式、初始刚度、延性和轴压承载力的影响,得到了荷载-位移曲线、初始刚度-槽口缺陷高度曲线、延性系数-槽口缺陷高度曲线、荷载-应变强度曲线以及极限承载力-槽口高度曲线。研究结果表明：对于带槽口缺陷的圆钢管短柱,管壁较厚的圆钢管短柱在槽口缺陷处只会产生凸起屈曲,而管壁较薄的圆钢管短柱在槽口缺陷处会有凸起屈曲和凹陷屈曲两种破坏模式。槽口缺陷会小概率使得圆钢管短柱有更明显的屈服平台,形成双峰曲线；槽口缺陷的存在会普遍减小圆钢管短柱的初始刚度和延性系数；槽口缺陷高度在0.5倍的壁厚范围内对初始刚度、延性系数和极限承载力的影响微乎其微；钢管管壁越薄,缺陷对极限承载力的影响愈加显著,其极限承载力下降幅值更大。最后,本文提出槽口缺陷影响系数并给出了考虑槽口缺陷的圆钢管短柱极限承载力计算公式。

Experimental study on compressive behavior of circular steel stub columns with notch defects

In this paper, the mechanical properties of circular steel tubes with notch defects in the circular steel pipe cutting process were studied. By screening 144 circular steel stub columns, 51 circular steel stub columns with notch defects were selected, and the 51 circular steel stub columns with notch defects were tested for axial compression performance. The effects of the types of notch defects, the height of the notch defects and the thickness of the steel pipes on failure mode, initial stiffness, ductility and axial bearing capacity of the specimen were analyzed. Load-displacementScurves, initial stiffness-height of notch curves, ductility-height of notch curves, load-strain intensityScurves and ultimate bearing capacity-height of notch curves are obtained. The results of the study show that: circular steel stub columns with large wall thickness will only show convex buckling at the notch defects; circular steel stub columns with small wall thickness will have convexities at the notch defects. The notch defect makes circular steel stub columns have a more obvious yield platform, forming a double-peak curve. The existence of notch defects will generally reduce the initial stiffness and ductility coefficient of circular steel stub columns. The notch defect height within 0.5 times the wall thickness has little effect on the initial stiffness, ductility coefficient, and ultimate bearing capacity. The thinner the wall of the steel pipe, the more significant the impact of the defect on the ultimate bearing capacity, and the greater the decrease in the ultimate bearing capacity. Finally, the paper proposes the influence factor of the notch defect and gives the formula for calculating the ultimate bearing capacity of circular steel stub columns considering the notch defect.