Research On FEM Model Updating In Spatial Reticulated Structural Dynamics

Spatial reticulated structures area extensively used in practical project. At present, there have been erected large numbers of the large span spatial structures, high-rise buildings and bridge structures and so on in home and abroad. Different countries have pushed the different codes for structural design working life, we now stand at the point where more detailed finite element models are not capable of delivering the improvements in performance. And the approach of numerical predictions to the behavior of a physical system is limited by the assumptions used in the development of the mathematical model. The used buildings have been varied dilapidation for varied reasons. Thereby, it's necessary to analyses the model of the building, and the structure is needed to be updated based on the result of the damage detection. So based on the corresponding references, according to the structural dynamics theory and finite element method, updating is a process fraught with the spatial reticulated structures.Firstly, structural dynamics' model updating is retrospective and analytic in the paper.The problem of how to compare experimental result from prototype structures with predicted from a corresponding finite element model is put forward, the modal reduction and the modal expansion is also given on the basement of correlation field.The choice of the parameters is necessary step in model updating. The measured data will contain a limited amount of information and to avoid some problem of ill-conditioned number. Then the updating parameters might rarely be achieved without the application of considerable physical insight.The direct methods of updating are based on the Lagrange multiplier methods and the character of the structural dynamics, the subspace iteration technique and the LDL~T factorization is used to solve the algorithm. The iterative methods ate mostly based on the statistics and the penalty function, including the penalty function methods and the minimum variance methods etc.Finally, the examples verify the accuracy and effectiveness of the analytical model and model updating algorithm in the paper, on the other hand, the dynamic design concept is presented in the paper.