The Assessment For Crane's Service Life And The Promotion Of Crane's Capacity

The 25t×27.5m rake crane of Baosteel section steel blooming plant features are big span and high working frequency. After 20 years of using, the crane trend to be deteriorated. Furthermore, with the change of the production process, the crane's lifting capacity must be increased. In this paper, the combining method of field test and numerical simulation is used to research the bridge crane. With these methods, the structure fatigue strength and fatigue life are evaluated and the corresponding schemes of equipment improvement and local modification to increase the crane's work ability and the safety factor are proposed. The lifting capacity of crane is increased from 25t to 30t.The main works of research are listed as follows:1) In order to fully investgate the health status of crane, the basic structure parameters and stress levels are measured. The testing results show that there aren't special structural problems except for an about 100mm crack in the crane girder. The resistance to deformation is becoming weaken.2) The finite element model of crane with various working conditions are built and calculated. The average error between calculated results and measured results is 5%, which shows that the finite element model is reasonable.3) Combining finite element analysis results and measured dataset, the data that are used to fatigue life assessment are corrected and the load spectrums of crane's dangerous parts are built according to the measured point's data.4) The fatigue life of the crane is calculated and the result shows the main beam structure has a long life to use.5) According to the testing and finite element analysis results, the strengthening and the mechanism reforms scheme of crane are proposed and the feasibility of scheme are verified by finite element simulation and mechanism calculation.