Research On Damage Identification Of Truss Structure

The whole rigidity of the spatial truss structure is good, and the technical and economic index is superior, so they are widely applied to the public buildings in large span, for instance, gymnasium, exhibition hall, airport lounge, station etc. During the long active service time, the structure maybe presents all kinds of damage because such reasons as tired accumulating, environment corroding and natural calamity function. If the damage can not be find in time, it will cause the expansion, even cause the collapse of the whole structure, so it is very essential to identify damage in the structures in time. To the simple structures, some riper methods of damage detection have existed. But to the large-scale complicated structure such as the spatial truss structures, because of all sorts of difficulty, the existing methods are difficult to apply to the actual engineering structures. So research on damage detection algorithm suitable for large-scale spatial truss structures has a great project meaning.The dynamic characteristics of structures are in closed relationship with the structural parameters, and structural damage will cause the dynamic characteristics shifts correspondently. Based on the vibration damage identification method is based on the structural dynamic test, through the dynamic test measured data analysis, the emergence of damage, location and extent can be judged.In this paper, with the specific object of research, the damage sensitive dynamic parameters of the structural diagnosis have been studied detailedly. The main contents include:Describing the status of research at home and abroad, this paper discusses and studies the diagnosis of structural damage theories and methods based on modal parameters.Concretely discuss the technology of damage identification based on the frequency, vibration mode, stiffness, flexibility. Using the example of the practical truss model, this paper compares damage identification results of the normalized rate of frequency, modal curvature, and flexibility curvature.Trying to put forward a three-step damage identification method for truss structures is given in this paper. In the first step, the probable damage area of the truss structure is identified; In the second step, the accurate damage location is identified in the probable damage area of the structure. And in the third step, the damage extents are identified for the damaged elements. This method can not only overcome the difficulties of the large complex structure of damage identification at present, but also improve efficiency of damage identification.On the basis of curvature mode theory, explain feasibility of damage identification using curvature mode. Discuss localization of damage identification in truss structure using curvature mode index, and improve it. Through a great deal calculate example, Improved curvature mode index can locate damage area.On the basis of modal strain energy theory, modal strain energy change (MSEC) is proposed as the injury indicator in this paper and validate MSEC of low modal can accurately identify the structural damage through numerical simulation. Further analyze the influence of different degree damage to the MSEC and compare with sensitivity of MSEC under the different damage location.On the basis of the presupposition that MSEC immovability of damage in fore-and-aft, the extent indicator is derived and verified through numerical simulation of different degree and different location. The validity and feasibility of this damage index has been confirmed.From the above analysis, we educe that the three-step damage identification method for truss structures can preferably assess the state of the structural damage. It shows that the parameters are effective and practical, so have some realistic significance and value.