Analysis Of Fatigue Life Of Tower Crane In Service Based On Test

With the rapid development of China’s economic construction and constant acceleration of urbanization construction, the phenomenon of tower crane’s full load and overloading are increasingly serious, and the number of accidents has continued to increase. At present, there is no uniform requirement for China’s tower crane standards for discarding, and many tower cranes manufactured in the1980s and1990s still remain in service.The working process of tower crane mainly includes lifting, luffing and slewing. The structure withstands impact load during the weight lifting and falling process, as well as alternating load during the luffing and slewing process. In addition, the tower crane is also exposed to the random wind load. These loads have a serious impact on the fatigue life of the tower crane. It is found that the fatigue failure is the main reason for the metal structure failure of the tower crane after the investigation and analysis of many accidents.To comprehensively analyze the fatigue life of tower crane, the field trial is carried out on the object of QTZ63tower crane. The study results of this thesis will provide theory basis for the design and fatigue life assessment of the tower crane. The main work is as follows,(1) Determining the analytical method. The nominal stress method is adopted for fatigue life analysis after the theoretical knowledge of fatigue damage is studied.(2) Establishing the finite element model. To analyze the stress level and distribution of state in the typical conditions, the finite element model of tower crane QTZ63is established. This will provide an important reference for the selection of field stress test pilot sites, as well as the fatigue life analysis of finite element results files.(3) Getting a load spectrum. According to the formulation of the test program, the spot stress test is carried out. Then, the stress-time history of the measured points in the typical conditions is collected and the data is analyzed by the DHDAS dynamic signal measurement system. To get the load spectrum, the test data is processed by the rain flow method.(4) Calculating and analyzing the fatigue life. The element result file and the load spectrum are loaded after the S-N curve is defined in the fatigue analysis software MSC.Fatigue. Based on the nominal stress method, the fatigue life of the tower crane is calculated. Finally, the result is analyzed and the design improvement opinion is proposed.