Improved TOPSIS Model and Its Application in Online Structural Health Monitoring System for Portal Crane

Abstract

Fracture of the metal structure is one of the foremost causes of accidents for portal cranes, and such an accident can be catastrophic, resulting in great loss of life and large expenses. Assessing the structural health of portal crane is important as it can keep security threats from further development. In an effort to evaluate the structural health of portal cranes in real time, an improved technique for order preference by similarity to an ideal solution (TOPSIS) model is presented in this paper. By integrating the fitting function of the bathtub curve, an optimization function f(aij) of condition matrix aij is proposed. Entropy-weight method is improved and applied to determine the weights of criteria. Based on the historical operation data, an update method for positive-ideal condition A+ and negative-ideal condition A− is elucidated. To further substantiate the improvement, the proposed methodological model is applied to an online structural health monitoring system for portal crane. Laboratory test and field test have been conducted. Structural strain, inclination, and pitch angle of portal crane are collected. Structural health assessment during lifting, luffing, and turning processes are carried out. The results show that the improved model gets a more stable and effective structural health assessment result, and is favorable for online structural health monitoring system. Thus, the proposed model can be applied to other problems of structural health assessment.