既有建筑结构构件的安全性分析

Safety analysis of structural members of existing buildings

提出了基于目标使用期的既有建筑结构构件承载能力验算的极限状态表达式。根据适用于既有结构的荷载和抗力概率模型,考虑14种代表性的结构构件、不同的可变荷载效应与永久荷载效应的比值、3种可变荷载效应与永久荷载效应的简单组合,对不同目标使用期内的荷载分项系数进行了优化分析。结果为:永久荷载分项系数γG=1.0(当永久荷载对结构有利时,γG=0.6),可变荷载分项系数γQ=1.3。由荷载分项系数进一步优化分析得出不同构件的承载力分项系数为γR=1.1～1.8。按目标可靠指标增减0.25确定了既有建筑结构构件承载能力的等级评定标准。经工程实例验证,所提分析方法更加符合实际情况,合理实用。

The limit state criteria for safety evaluation of existing building structures was established on the basis of the target period of usage. According to the probability models of the load and the resistance for existing building structures, partial safety factors of load effect for different target periods of usage were deduced by optimal analysis of 14 types of typical structural members taking into account of the different ratios of live load effect to dead load effect and 3 types of simple load combinations for dead load and live load.The results showed that the partial safety factor for dead load γG is 1.0 (if the dead load is helpful to the structure, the partial safety factor for the dead load γG will be 0.6), and the partial safety factor for live load γQ is 1.3. Based on the suggested load partial safety factors, resistance partial safety factors (γR), which are 1.1～1.8 for different kinds of structural members, were determined by further optimal analysis. Finally, the safety classification standard for exiting building structural members was developed assuming that the variation value of target reliability index is 0.25. Calculation results for engineering examples showed that the method proposed in this paper is rational and suitable for the safety analysis of existing building structures.