Fatigue Reliability Analysis And Evaluation Of Steel Crane Beam

According to statistics,80% of industrial crane beams in China are damaged due to fatigue.The theory of structural design has been developed from allowable stress to probabilistic limit state with the introduction of reliability concept,but the fatigue design is still designed by the allowable stress method.Because of the complexity of the fatigue failure mechanism,the fatigue reliability of the steel crane beam is affected by many factors,including the diversity of fatigue load,the geometric structure form,the fatigue strength of the material and the use environment of the structure.Based on the theory of structural reliability,the whole use process of the steel crane beam is considered as a random process.The effect and resistance of the steel crane beam are considered as random variables,and the fatigue dynamic reliability model based on the Miner linear cumulative damage theory is studied.The fatigue reliability factors of steel crane girder are analyzed by using the fatigue dynamic reliability calculation model.The specific research contents include the following aspects:1.The random distribution types of fatigue stress amplitudes of steel structure crane girder are studied,and the selection of distribution parameters is analyzed.By comparing with the data of the field stress test and experiment of a steel plant,the stress amplitude clothing of steel structure crane beam can be described by Weibull distribution,and it is carried out when the span,section type,crane load and working environment of the steel crane beam are similar.Fatigue reliability analysis can be based on similar structure Weibull distribution parameters for fatigue reliability calculation.2.A comparative analysis of the S-N curves in the existing steel structure codes at home and abroad is given.By comparing the curves of eight kinds of connections in GB5007-2003 and the S-N curve proposed by IIW,the effect of low stress amplitude on the actual use is weakened,and the S-N curve in GB5007-2003 is corrected.3.Using the fatigue dynamic reliability analysis model in FE-safe software,the influences of the form of variable section support and the size of the detail structure,the form of sealing plate,the surface roughness and the residual stress on the fatigue reliability of the steel crane beam are calculated and analyzed.Based on the law of influence,the paper puts forward some suggestions for fatigue design,operation and maintenance of steel crane beams.