Bridge Crane Girder Structure Time-varying Reliability Evaluation Method Research

According to work characteristics of the overhead traveling crane, the crackpropagation path of the main beam structure to be explored. Based on fracturemechanics and damage accumulation theory, according to finite elementmeshing “the weakest” unit crack subclass deficiency,“the weakest” unit quitworking, the load redistribution. Under the continuing role of the repeatedloading, crack gradually expanded, due to the continuity of the adjacent cells,internal force passed to the “second weakness” unit, making it a “weakest” unit.And so on, the structure to be a plastic deformation state, crack reaches a criticalvalue, thus formed the crack propagation path. By expanding the function of“element birth and death” technique of ANSYS software and using developmentenvironment MFC of Visual C++6.0, integrated the secondary developmentlanguage Pro/Toolkit in the Pro/E software and secondary development languageAPDL in the ANSYS software, so the overhead traveling crane bridge structureinteraction parameter modeling and finite element analysis of visualizationsoftware is developed.Static reliability in the assessment of structure without considering thestructural resistance and load effects change over time, time reliability theoryhas been used. After considering the impact factors of the structure of theoverhead traveling crane and structural bearing capacity data distribution in theprocess of crack propagation, the prediction model of structural resistance todegradation was proposed. Using measured data, simulation of randomprocesses, time-varying model of load effects (main beam weight, car weight,car position, inertial load, lifting load and wind load) was established.Time-varying reliability model of the main beam structure for overheadtraveling crane was established; Time-varying reliability index was obtained,and compared with the value obtained by the static reliability method. Projectexamples show that taking into account the structural resistance and load effectsas time goes by, time-varying model can better reflect the actual reliability of thestructure, and verify the time-varying model is reasonable.