不同圆心角圆端形钢管混凝土短柱轴压性能

为研究圆心角60°和120°圆端形钢管混凝土短柱轴压力学性能,对4个圆端形钢管混凝土短柱进行轴压试验,探究不同圆心角和宽厚比对其极限承载力的影响。基于试验结果,应用有限元软件ABAQUS进行三维实体建模,对圆端形钢管混凝土短柱进行参数分析,研究了钢材强度、混凝土强度、宽厚比、高宽比、尺寸效应等对极限承载力的影响。基于参数分析,建立圆心角为60°和120°圆端形钢管混凝土短柱极限承载力实用计算公式。结果表明:破坏形态均为局部屈曲破坏,且平直段区域均出现局部屈曲现象; 随圆心角增大,构件极限承载力增大; 随宽厚比增大,极限承载力呈现下降趋势; 当圆弧段圆心角从60°增大至120°时,强度指标降低,表明整体约束效应减弱; 圆端形钢管混凝土轴压短柱的整体约束效应随圆心角增大而减小; 随着钢材强度、混凝土强度的增大和构件宽厚比的减小,极限承载力逐渐增大; 不同圆心角的尺寸效应对其极限承载力与初始刚度的影响类似,随着构件尺寸增大,极限承载力与初始刚度均呈现增大的趋势。

Behavior of Round-ended Concrete-filled Steel Tube Stub Column with Different Central Angles Under Axial Load

In order to study the mechanical properties of 60° and 120° round-ended concrete-filled steel tube stub columns under axial compression, four round-ended concrete-filled steel tube stub columns were tested to investigate the ultimate bearing capacity, considering the influence of different central angles and width-to-thickness ratios. Based on the test results, the finite element software ABAQUS was used to model the 3D solid. The parameters of the proposed round-ended concrete-filled steel tube stub columns were analyzed, and the influences of steel strength, concrete strength, width-thickness ratio, height-width ratio and size effect on the ultimate bearing capacity were studied. The results show that the failure modes are all local buckling, and the failure locations are located in the straight section. The ultimate bearing capacity of the columns increases when the central angle increases. The ultimate bearing capacity shows a downward trend when the width-thickness ratio increases. When the central angle of the circular arc increases from 60° to 120°, the strength index decreases, indicating that the overall confinement effect is weakened. The overall confinement effect of the round-ended concrete-filled steel tube stub column under axial load decreases with the increase of the central angle. With the increases of steel strength, concrete strength and decrease of width-to-thickness ratio, the ultimate bearing capacity increases gradually. The size effects of different central angles are similar to that of the initial stiffness. As the sizes of the member increases, the ultimate bearing capacity and initial stiffness show an increasing trend.