广义圆端形钢管混凝土短柱轴压承载力公式

Formula for axial compressive bearing capacity of generalized round-ended CFST short columns

为研究圆形、圆端形、变圆心角圆端形和矩形钢管混凝土短柱轴压承载力的统一计算公式,采用两种不同本构关系建立广义圆端形钢管混凝土轴压短柱的ABAQUS有限元模型,利用90个钢管混凝土短柱轴压试验数据与有限元计算结果进行对比,验证了有限元模型的可靠性。通过改变构件的截面形状和材料强度,设置了9组共90个广义圆端形钢管混凝土轴压短柱有限元模型。对有限元计算结果展开参数分析,研究截面平直段高宽比和截面圆心角对钢管混凝土约束效应的影响。基于统一理论和约束分区方法,以截面形状影响系数对套箍系数进行了修正,并在GB 50936—2014推荐的圆形钢管混凝土短柱轴压承载力公式的基础上,建立了广义圆端形钢管混凝土短柱的轴压承载力简化计算公式,最后采用452个广义圆端形钢管混凝土短柱轴压试验数据对公式的准确性进行了验证。结果表明:当材料强度和含钢率一定时,广义圆端形钢管混凝土柱的套箍约束效应随着截面平直段高宽比的增大而减小,随着截面圆心角的增大而增大;简化公式的计算结果与试验结果吻合良好,适用于圆形、圆端形、变圆心角圆端形及矩形钢管混凝土短柱的轴压承载力计算。

In order to study the unified calculation formula of the axial compressive bearing capacity of circular,round-ended,different central angle round-ended and rectangular CFST short columns,two different constitutive relations were used to establish the ABAQUS finite element model,and the axial compression test data of 90 CFST short columns were compared with the finite element calculation results to verify the reliability of the finite element model.By changing the cross-sectional shape and material strength of the members,9 groups of 90 generalized round-ended CFST short columns with axial compression finite element models were set up.The parametric analysis of the finite element calculation results was carried out,and the influence of the aspect ratio of the straight section and the central angle on the confinement effect of the CFST was studied.Based on the unified theory and the constraint partition method,the confinement factor was modified by the cross-sectional shape influence coefficient,and on the basis of the axial compressive bearing capacity formula of the circular CFST short column recommended by GB 50936—2014.A simplified calculation formula for the axial compressive bearing capacity of generalized round-ended CFST short columns was established.Finally,the accuracy of the formula was verified by using the axial compression test data of 452 generalized round-ended CFST short columns.The results show that when the material strength and steel content are constant,the hoop restraint effect of the generalized round-ended CFST column decreases with the increase of the aspect ratio of the straight section of the section,and increases with the increase of the central angle of the section.The calculation results of the formula are in good agreement with the test results,and are suitable for the calculation of the axial compressive bearing capacity of the circular,round-ended,different central angle round-ended and rectangular-section CFST short columns.