Time - Dependent Reliability Analysis Of Metal Structure Of Tower Crane

Because of the high efficiency, large rotation radius as well as great lifting height, tower crane has been widely used in the area of industry and civil engineering, especially in high-rise building construction. According to incomplete statistics, a consider amount of tower cranes have been worked for a long time, which are likely to cause serious accidents due to the existence of security risks. Therefore, the evaluation of old tower cranes for reliable and safety working has become an urgent problem to be solved. Till to date, the consolidated national scrapped standards of tower crane are not available. Based on this background, the metal structure of tower crane is analyzed with time-variant reliability analysis method, which can provide theoretical guidance for the safety assessment of tower cranes.According to the structural system reliability theory and actual working condition of tower crane, the main content and methods of this paper are as follows:The main failure mode and ultimate lifting capacity of tower crane under different working conditions are simulated by means of the minimum incremental loading criterion, combined with bilinear isotropic plasticity of ANSYS. With the transient analysis, hoisting and slewing movements of the tower crane were imitated to get the stress-time history of tower crane’s metal structure. Besides, based on the rain-flow counting method, the stress ranges and cycle numbers can be obtained from stress-time history. Then, according to the S-N curve of materials and the Miner rule, the fatigue cumulative damage can be calculated with stress ranges and cycle numbers information. Finally, the metal structure’s reliability analysis is conducted by time-variant reliability analysis method. It is an effective way to improve the simulation efficiency by the minimum incremental loading criterion, combined with bilinear isotropic plasticity. In addition, the simulation of main failure mode can determine the public failure elements.Through above research, the values of reliability corresponding to different service years are obtained, which provide theoretical basis for scientific evaluation of the tower crane.