RELIABILITY ANALYSIS OF AXIAL BEARING CAPACITY OF CONCRETE FILLED STEEL TUBULAR STUB COLUMNS WITH DIFFERENT CROSS SECTIONS BASED ON SIMPLIFIED FOURTH-MOMENT METHOD

A new point estimate method and a simplified fourth-moment method are used to analyze the reliability of bearing capacity formula (proposed by Ding Faxing) of concrete-filled steel tubular stub columns (CFST) under axial compression considering the shape constraint coefficient of different steel tube cross sections. The influences of different section shapes, different strengths of concrete and steel, two load combinations and different load ratios on the reliability index are considered. The results show that: the reliability indexes of the bearing capacity formulas of CFST with different cross sections are higher than 3.7, which meets the requirements of target reliability index of 3.2; When the ratio of office live load to dead load is 1.0, the higher the concrete strength, the larger the reliability index.