Study On Gird Structure Damage Identification Methods Based On Data Fusion

Space grid structure is a high order statically indeterminate structure. The structure is complex and can achieve larger span, which more used in important public buildings. Construction negligence, improper use, accidental load and other factors cannot be completely avoided. Once the damage was not found in time, the engineering accidents may occur at any time. Such incidents tend to bring property damage and bodily harm. So the study of space grid structure damage detection is particularly important. According to the project problem, this paper mainly research on the following aspects:(1) This paper summarizes the existing damage detection methods. It finds that the space grid structure damage identification technology is not mature. Because nodes and bars are numerous, most grid structure damage stays in numerical simulation stage. Therefore, this paper established the experimental model grid. The grid structure damaged before and after was carried out to strain test and acceleration tests respectively. After the modal analysis of acceleration values, the first eight natural frequencies and mode shapes of the structure has been obtained.(2) To get the damage identification results, the modal data analysis uses the following three methods: the damage identification method based on coordinate modal confirmation criterion, the damage identification method based on curvature mode difference, and the damage identification method based on the rate of change of the ratio of modal flexibility. Meanwhile, the strain data analysis uses the damage identification method based on strain modal. The four results showed that the injury indicators existed misjudgment behavior, more or less.(3) In order to improve the accuracy of damage identification, data fusion method is introduced to the structural damage identification field. The basic principle and levels of data fusion, the basic concepts and its synthesis rules of the D-S evidence theory were introduced. Using D-S evidence theory to analyze the results of the above four, through trust distribution and information combination, the synergistic and accurate recognition result is obtained. After several rounds of integration, the injury trust level of 128 bars has been determined accurately. This is consistent with the experimental situation.Various single network structure damage identification indicators exists misjudgment behavior. So this paper applies the D-S data fusion to the grid structure damage identification. The theoretical significance is clear, and it has been reliably verified in the experiment. It is proved that this method can accurately identify the damage location. This has significant theoretical and practical value of the space frame structure damage recognition.