Stress Spectrum Test Of Crane Runway Girders And Fatigue Life Prediction By DFR Method

Fatigue life of a structure can be described as the number of cycles of loadingrequired to initiate and propagate a fatigue crack to fracture. Therefore, structures subjectto dynamic actions may be prone to serious fatigue problems and results may becatastrophic. Crane runway girders are one of these types of structures at risk. Due to noobvious plastic deformation before fatigue failure, it can bring enormous economic lossesand casualties that endanger of production. Fatigue life of the crane runway girders is oftenused as one of the key indicators of factory security control, therefore, the significantamount of research on fatigue life prediction was performed, which has a very importantvalue in practice and plays an important role in management and maintenance of industrialworkshop.In this study, the four steel crane beams in a steel factory workshop were tested forthe maximum stresses produced by the practice loading. The test data were then inputtedinto the MATLAB program which was written on basis of the principles and rules of therain flow count method. By analyzing the output results, we obtained the stress spectrumsof steel crane beam key parts, which could be used for fatigue life-span prediction andsafety assessment.After the stress spectrums testing, the detail fatigue rating (DFR) method wasintroduced to predict the fatigue life of crane runway girders. The formulation of fatiguereliability life and the relation of fatigue property parameters with the DFR value werefirstly summarized, based on which the general method and major procedure to analyzestructural fatigue reliability life were proposed. It can be found through the calculationsand comparative analysis the predictions of fatigue life were consistent with the target lifeof crane runway girder, which validated the feasibility of the DFR method extended theapplication range of the DFR method.In conclusion, through investigating the load spectrum of every crane runway girderand analyzing the major influencing factors on the fatigue life, the fatigue life of the steel crane runway girders was studied.