Maintenance Strategy And Lifetime Prediction Research Of Existing Space Latticed Structures Based On The Reliability Of Symptoms

As a typical representative of the large-span space structure, the space latticed structure has been developed rapidly during last three or four decades. As for the detection and identification of existing space latticed structures, there are not systematic research and engineering applications in China or abroad. The research for the state assessment of existing structures was mainly concentrated in the field of concrete structures and bridges. There are three methods mainly used, i.e. the traditional empirical method, practical identification method and reliability identification method while the relative scientific reliability method was highlighted, including reliability theory for structures in design and reliability theory for existing structures. The differences between existing structures and designing structures about reliability theory were discussed, mainly include the considered time interval when calculating the reliability as well as the statistical regularities of the resistance and load on the structures.To get a better understanding of symptom-based reliability, a detailed derivation process was given. Weibull distribution and the proportional hazards model were introduced, which were combined with symptom-based reliability, as a link between different structures or components. The Square Pyramid grid finite element model was established using spatial structure calculation software MST. Using existing steel corrosion law the corrosion process of actual structure was simulated. Symptom changes in the structure corrosion process were observed by several finite element calculations. By reducing the cross section of the bar, the actual buckling member bar was simulated. Similarly, removing the tension bar can simulate the connection failure between the tension bar and node. We can treat the destruction of any members as the limit state of the space latticed structure.The probability design module of ANSYS has been used to calculate reliability and analyze sensitivity. We can get the key target of maintenance among space latticed structure components by sensitivity analysis. The probability distribution of sequence number for the member was obtained, which get maximum or minimum stress. We can treat those members as key targets for structural health monitoring of space latticed structure, whose probability of showing greater stress are larger. The method of symptom-based reliability was used to do reliability assessment and life prediction of key targets when monitoring structure. So we can take the minimum value of the life prediction for members as life remaining value of the space latticed structure.