Container Handling Bridge Metal Structures Fatigue Crack Control And Management

Fatigue breaking is the main form of structure invalidation of port crane, and as a system under loads, its invalidation causes not only the disability of crane, but also fatal accidents which is a great danger to both production and personal safety. In this paper, No.4 container crane in Xiamen Haitian Container Terminal (XHCT) is taken as an example to study the problem of fatigue crack control and regulation of metal structure.The safety evaluation of crane metal structure includes routine check, fatigue strength testing and remnant life estimation. At the beginning of the paper, we analyze and summarize its foundation, testing items and procedures of structure safety evaluation, and put forward several measures as reference for metal structure daily regulation of port cranes, namely testing structure stress, which is the main factor of safety, as well as crack, deformation and rust corruption, especially on those extremely old machines. The joint state of two components and welding line on important section of the main structure are also main checking factors.Fatigue strength testing and remnant life estimation of port cranes' metal structure are the focus of the paper. After comparison of various fatigue theories and analysis methods, we establish a model for fatigue crack analysis and control on the basis of fracture mechanics and damnification mechanics, which is specifically designed for fatigue crack regulation of port cranes' metal structure. In the model, the concept of boundary stress is advanced and the main factors related to it are analyzed. The exact values of boundary stress of different materials under loads with various stresses circulation characteristics are also calculated and fixed. We analyze those circulations whose stress levels are higher than boundary stress, and compute the length of the critical crack of different structures. According to the linear accumulative damnification theory and COD theory, the crack growing life from the initiated length to the critical length is also calculated by the model, which can be theoretical reference for the selection of checking points and establishment of checking intervals of these points.At the end of the paper, the model set up in former chapter is applied to...