圆空心钢管混凝土短柱在轴向压力作用下的可靠性分析
Reliability analysis of circular hollow concrete filled steel tube short column under axial compression

为分析圆空心钢管混凝土短柱在轴向压力作用下的可靠性，以笔者及其他学者所进行的圆空心钢管混凝土轴压短柱试验数据为统计样本，结合Normal、Lognormal、Weibull、Gamma 4种分布形式，考虑模型误差，分别根据《钢管混凝土结构技术规范》（GB 50936—2014）中的钢管混凝土柱轴压承载力计算公式与作者提出的修正公式，运用Monte Carlo法计算得到了规范公式与修正公式的可靠度指标。结果表明：依据两种公式计算得到的可靠度指标均基本满足目标可靠度指标3.7的要求；规范公式的可靠度指标较大，约为修正公式的1.05倍，计算结果较为可靠；可靠度指标随着混凝土强度和荷载效应比的提高而上升，随着含钢率的提高而下降，钢材强度和空心率的变化，可靠度指标的变化不明显。考虑上述4种分布类型对抗力误差的影响，分析了各参数因素对抗力分项系数的影响，结果表明：计算模型误差分布类型和活载类型对抗力分项系数的影响不明显，安全等级和荷载效应比影响较为明显；考虑实际工程中常用的荷载效应比，提出荷载效应比不同时抗力分项系数取值分别为1.21、1.32、1.41。
In order to analyze the reliability of circular hollow concrete filled steel tube short column under axial compression, the experimental results as well as the data sets from literatures were collected. The model errors were taken into consideration via Normal, Lognormal, Weibull, Gamma distribution assumptions. Reliability analysis was carried out based on Technical Code of Concrete Filled Steel Tube Structure and the modified formula presented by the authors. Monte Carlo sampling was also performed and the calculated reliabilities satisfy the target reliability index. The reliability index of the code formula is greater than that of the modified formula within 5%. As the concrete strength and loading ratio increase, the reliability index increases. The reliability index decreases with the reduced steel ratio. The hollow ratio and steel strength have marginal influence on the reliability index. Parameter analysis was also carried out in considering the influence of model error distribution types, which indicated that mode error and live load type have less significant influence on partial factor of resistance, than the safety levels and the loading ratio. The partial factor of resistance under different loading ratios should be 1.21, 1.32 and 1.41, respectively.