Technical And Experimental Research On Steel Structural Health Monitoring Of Tower Cranes

As a kind of typical large engineering machinery, the tower crane is high risky special equipment. It can cause tremendous economic loss because of the work of professionals to maintain and the shutdown of the machine when the tower crane goes wrong; more importantly, it can also cause fatal accidents when the tower crane falls down. The security problem of tower cranes will influence not only the individual safety and health, but also the social stability and economic development. It has become the focus to monitor health condition of the tower crane, find out the potential safety hazard on time, improve operation reliability and reduce or eliminate accident.In this paper, aimed at the online steel structural damage diagnosis of tower cranes, deeply and systematically researches are carried out for steel structural damage diagnosis of tower cranes by combining the current situation and the research focus of structural health monitoring. The main results are described as follows:Firstly, the tower body top inclination model is studied systematically. The tower body top inclination feature model, which characterizes the top inclination, is established in normal state; the tower body top inclination feature model in normal and no loading state and in steel structural damage state of tower bodies are analyzed and established. On the basis of this model, the top inclination feature model which can recognize the steel structural damage orientation of the tower body is established, too; and the implementation arithmetic of this model is investigated. The validity of this model is testified by experiments. This model is easy to realize real-time control, and it can be used as a kind of control model.Secondly, the judgment criterion of steel structural sound condition of tower cranes is proposed. Based on the time series method, the time series stiffness spacing model, which can recognize the steel structural sound condition, overloading state and violation operation, is established. The Matlab program for this model is compiled.Thirdly, the steel structural damage diagnosis method of tower crane based on support vector machine is investigated. The sensitivity of changing ratio of displacement to structural damage is analyzed. The steel structural damage diagnosis method based on the changing ratio of displacement and support vector machine is proposed. The changing ratio of displacement is taken as input data to diagnose the steel structural damage of tower crane; the effect of indentifying damage is good.Fourthly, the damage diagnosis test for the steel structure of tower cranes is carried out under ambient vibration. The feasibility of using the top inclination data of tower bodies measured by the inclination sensor as the output characteristic quantity to recognize the steel structural damage is testified by two experiments; one is the damage experiment of two main chords connected by high-strength bolt and the other is the damage experiment of the whole tower crane used in construction site. The validity of the steel structural damage diagnosis method, based on the changing ratio of displacement and the support vector machine, is verified in this paper.Fifthly, the integrated monitoring system of tower cranes is designed systematically, and the management software is developed. This system consists of functions such as the structure monitoring, health diagnosis and management evaluation; and it can recognize the steel structural damage of tower cranes and monitor the work environment and each performance index of tower cranes in real-time. The management software developed has powerful ability of data process, and can realize results visualization; also, this software has a friendly interface and is easy to operate.