高强方钢管超高性能混凝土短柱轴压承载力计算方法研究

为研究高强方钢管超高性能混凝土(UHPC)短柱轴压承载性能，进行了40根高强方钢管UHPC短柱轴压荷载试验。结果表明：套箍系数是影响方钢管UHPC短柱轴压破坏过程和形态的主要因素，极限荷载随套箍系数增大而增大，核心UHPC强度提高幅度均值为15%。比较分析了多部现行规范、规程的承载力计算方法的差异，相关规范与规程中不考虑钢管约束效应时，其承载力计算值的均值低于试验极限荷载值，考虑约束效应的参数适用性受限。并基于叠加原理采用线性回归分析和考虑等效约束作用分别建立了高强方钢管UHPC短柱轴压承载力的实用计算式和理论分析式。

Calculation methods of axial bearing capacity of short square UHPC filled high strength steel tubular columns

To investigate the axial bearing capacity of square ultra-high performance concrete (UHPC) filled high strength short steel tubular columns, 40 specimens were tested under uniaxial compression. The results indicate that the failure process and modes of the short square UHPC filled steel tubular columns are affected by the confinement index, and the ultimate load of short square UHPC filled high strength steel tubular columns increases with increasing of the confinement coefficient. The average value of the strength of the core UHPC increases by 15%. The differences of calculation methods in the relevant specifications were then analyzed. It is found that the calculated values of the bearing capacity in the relevant specifications are all lower than those of the experimental results when the confinement effects of steel tube are neglected; in the meanwhile, the applicability of the formula with the confinement effects of steel tube taken into consideration is limited. Based on the concept of superposition, the practical calculation and the theoretical analysis calculation of axial compressive capacity, using linear regression analysis and considering the effect of equivalent lateral confinement, are proposed respectively.