验证荷载条件下既有梁桥可靠度分析

Analysis on Reliability of Existing Bridge Considering Proof Load

分析了抗力服从不同先验分布时其后验分布的数字特征变化规律,建立了验证荷载条件下的抗力概率模型;结合条件概率的方法,建立了验证荷载条件下的结构可靠指标计算公式。并从验证荷载前后结构功能函数相关系数、验证荷载取值等方面对一实例桥梁进行了可靠度分析,同时研究了恒载参数、活载参数对考虑验证荷载的既有桥梁结构可靠度的影响。结果表明,已服役期的验证荷载对桥梁结构可靠指标的影响不能忽视,考虑验证荷载,时既有桥梁结构可靠指标比不考虑验证荷载时要大;同一验证荷载,当验证荷载前后结构的功能函数为高级相关时,结构可靠度增长幅度大;考虑验证荷载时,既有桥梁结构可靠度随着恒载及活载变异系数的增大而递减。

The statistics characters of posterior probability distribution of the resistance following different prior probability distributions were analyzed,and the resistance probability model under proof load was built.Combined with conditional probability method,the calculating formula of proof load reliability indices of structure was established.One example of the reliability analysis of a bridge considering proof load values and the correlation coefficient of structure function before and after applying proof load was presented,and the influence of dead load and live load parameters on structural reliability of existing bridges considering proof load was studied too.The results show that（1） the impact of proof load on existing bridges＇ reliability should not be ignored,the reliability indices become higher when considering proof load;（2） under the same proof load,the increasing rate of structural reliability is higher when those two functions are highly related before and after applying proof load;（3） the existing bridges＇ reliability is decreasing with the increases of the variation coefficient of dead load and live load considering proof load.