承载力折减系数对结构构件可靠度的影响分析

Analysis of the Effect of Load-bearing Capacity Reduction Factor on the Reliability of Structural Members

构件承载力评定是鉴定结构构件安全性的重要指标。本文采用一阶二次矩阵法得出了不同承载力折减系数下的构件可靠指标计算公式,并结合多种常用材料的抗力参数,根据非迭代方法计算出了不同结构构件对应的可靠指标。结果表明:可变荷载对结构可靠度的贡献优于永久荷载的影响,但当可变荷载与永久荷载标准值之比达到一定限值时,构件的可靠度不再提高。依照现行标准要求的承载力折减系数计算可知,结构构件可靠指标大致呈等差数列排布,此种划分方法下得出的结果与构件实际失效概率存在较大偏差,可靠指标降幅过大将对构件安全性鉴定工作产生不利影响。

The evaluation of member load carrying capacity is an important index to identify the safety of structural members.In this paper,the first-order quadratic matrix method is used to derive the formula for calculating the reliability indexes of members under different bearing capacity reduction factors,and the corresponding reliability indexes of different structural members are calculated according to the non-iterative method by combining the resistance parameters of a variety of commonly used materials.The results show that the contribution of variable load to structural reliability is better than that of permanent load,but when the ratio of variable load to the standard value of permanent load reaches a certain limit,the reliability of the members will not be improved.According to the calculation of the load capacity reduction factor required by the current standard,the reliability index of structural components is roughly arranged in an equidistant series,and the results obtained under this division method have a large deviation from the actual failure probability of components,and a large reduction in the reliability index will have a negative impact on the safety appraisal work of components.