Equivalent Normal Distribution Method And Its Application In Engineering Structure Reliability Design

China's current national standards for the design of engineering structures including highway engineering,port engineering,railway engineering,hydraulic engineering,as well as construction engineering all employ the first order reliability method(FORM)limit state design theory and method marked by reliability index ?.When designing basic variables,for example,the related resistance and variables of action effect comply with non-normal distribution,the method aiming at obtaining reliability index ? will adopt equivalent normal design to get ? through iteration.However,the various methods of equivalent normal and the difference of structural performance functions will all impose an impact on iterative convergence rate and precision of the obtained ?.This paper recommended and discussed five equivalent normal distribution methods with the measured data of vehicle loads on highway and bridge as empirical background,compared their differences under different performance functions,and took iterative convergence rate and the precision of the obtained ? as the standard to verify whether they were good or bad,and gave different performance functions specifically suitable for each equivalent normal distribution method.At present,our country have used engineering structure reliability design with unified standards at lease nearly 20 years,some used more than thirty years.Because in the process of compiling at that time,widely use calibration to finalize the reliability index on the standard and specification,so it's common reflect relatively small in the process of using.According to the present century,the objective environment of our country's rapid development of national economy and the implementation of The Belt and Road policy,it is imperative to revision of the national standards and specifications.The statistical application research used for the reserve of the design philosophy and statistical approach for revising the next generation's standards and specifications.