Safety Assessment For Metallic Structure Of In-service Gantry Crane

Bridge cranes are widely used in shipyards for the transportation, joint, turning and other operations of the large scale hull sections. Bridge cranes are commonly suffered with serious corrosion problems because of the bad working conditions, thus the safety of these devices are often threatened by the structural fatigue problems. And the trend of being large-scale of cranes and the complexity of the loading conditions make the ultimate strength and the bearing capacity problems of the cranes more and more important. Yet the occasionally happened accidents always cause economic losses, destructions of devices and even people lifes. So it is very necessary to carry out structural analysis and safety assessment for the in-service and especially those aging crane devices.Safety assessments for the metallic structure of in-service bridge crane are carried out in this paper. System for crane structure safety assessment is developed based on the MSC.Patran platform using the Patran Command Language (PCL), which can achieve parametric modeling and safety assessment based on crane design rules. Graphical user interfaces (GUI) are deveioped with PCL. These functional interfaces are interactive and visible, which are convenient to use.Structural fatigue analysis and ultimate strength analysis under corrosion effection are carried out in this paper. The results indicate that the corrosion effection reduces the structural fatigue life and ultimate bearing capacity remarkably; the reduction of fatigue life under corrosion can reach up to 18.9% comparing to that without corrosion, and the reduction of ultimate bearing capacity under corrosion can reach up to 6.7% of the intact structure. During the whole service time area, the reduction curves of fatigue life and ultimate bearing capacity are given as a kind of forecasting and assessment.