Hybrid Time-Varying Reliability Analysis Of Bridge Crane Structure Based On PHI2

Bridge crane is a wide range of large-scale handling equipment,which safety and reliability directly affect the probability of accidents.As the main bearing part of the bridge crane,the reliability of the bridge frame determines the reliability and safety of the whole machine.Traditional reliability analysis only considers a single uncertainty problem,which index is a static parameter without considering the cumulative effect of time.At the same time,in the process of reliability solving,the safety limit state function of the bridge crane structure has a complicated form and high calculation cost.Therefore,to comprehensively consider the variable characteristics of insufficient sample data and sufficient data,in this paper,a PHI2-based hybrid time-varying reliability model of bridge cranes is constructed and analyzed.In addition,this model also considers the corrosion factors of the material,the attenuation of resistance and the complexity of the limit state function.The main work of the thesis is as follows:(1)In order to give the strength and stiffness failure criterion and the corresponding limit state function,the metal structure of the main girder of the bridge crane is analyzed.Aiming at the shortcomings of the complicated form of the limit function and the large amount of calculation,the response surface method is improved.The improved response surface method is used to replace the limit state function to solve the reliability.Three simple calculation examples verify the efficiency and accuracy of the proposed improved response surface method.(2)To overcome the lack of sample data,interval information is used to describe uncertain factors,and the interval information is transformed into probability information which obeys the truncated normal distribution.In addition,considering the resistance attenuation caused by time changes and the corrosion of the main beam section,the lifting load is regarded as a random process.The improved PHI2 method is used to solve the span rate,and the reliability index and cumulative failure probability during the design period are obtained.(3)With C# language software as the carrier,the "hybrid time-varying reliability evaluation system of bridge cranes" was designed.This system can realize the analysis and verification of stress and the calculation of the reliability index and the cumulative failure probability of the bridge crane main girder structure during the design period.The verification of engineering examples shows that the reliability index considering the cumulative effect of time is significantly lower than the reliability index without considering the cumulative effect of time.This result indicates that the probability of failure increases with the increase in the number of years,which is consistent with the actual project.