复式钢管高强混凝土柱轴压试验研究

Axial compressive test of columns with multi barrel tube-confined high performance concrete

通过20个复式钢管高强混凝土柱试件的轴心受压试验,对其破坏形态、受力机理、刚度和承载力进行研究。结果表明:内外钢管在轴压力作用下同时屈服,从主要承受竖向压力转变为主要承受环向拉力,内外层混凝土因受套箍约束而具有更高的抗压强度;随着等效套箍指标的增大,试件承载力与屈服荷载的比值增大、峰值后曲线趋于水平,破坏形态从剪切破坏转变成腰鼓形破坏;混凝土抗压强度、钢管屈服强度、内外管直径比、外管厚径比和内管厚径比是影响复式钢管高强混凝土柱轴心受压承载力的主要因素。试验结果及有限元分析表明,理想弹塑性本构模型适宜作为钢管混凝土轴压柱中钢管的本构模型。利用非线性有限元分析软件ABAQUS进行有限元分析,其结果与试验结果吻合良好。通过对试验结果的统计分析,提出了复式钢管高强混凝土柱轴心受压承载力实用计算式,可供实际工程设计参考应用。

Through the axial compression tests of 20 specimens, the failure modes, force mechanism, stiffness and bearing capacity of the multi barrel tube confined with high performance concrete columns were observed. The results show that the internal and external steel tubes yield simultaneously and convert from bearing vertical compressive force to circumferential tensile force under compression, making it possible for concrete to resist higher compressive strength. With the increase of equivalent confinement index, the ratio of bearing capacity and yield value increases, the peak curve tends to level, the failure mode transfers from shearing failure to drum-shaped failure. Compressive strength of concrete, yield strength of steel tube, diameter ratio and thickness and radius ratio of the internal and external steel tubes are the main factors that have effect on the axial load bearing capacity. On the basis of experimental study, the ideal elasto-plastie constitutive model was found to be more proper to simulate the constitutive model of the steel tube. Nonlinear FEA of the specimens was performed by ABAQUS, results of which match well with the experimental results. Based on the statistical analysis of the test results, practical formulas for axial compression bearing capacity are proposed in this paper, which can be referenced in practical engineering applications.