Based On Particle Swarm Optimization Algorithm For Finite Element Model Updating

Accurate and reliable structural analysis is closely related to an accurate finite elementmodel. But under the influence of materials, construction, environment and so on, there isoften a larger error between the finite element model and the actual engineering structure. Inrecent years, it has become a hot issue to improve the accuracy of the simulation model of theexisting structure and reduce the error between the finite element model and the measuredresults. A lot of research results have been gained. However, due to the level of awareness,testing techniques and field conditions, There still exists many problems in the updating finiteelement model of structural damage identification based on the dynamic testing. They can’t beeffectively applied to engineering practice. For this reason, it is very important in practice todevelop a a reliable and accurate finite element updating model of the structural damageidentification. On the basis of existing research results, the updating method of the bridgestructure finite element model is investigated in this paper. Main works are:(1) Taking an actual bridge operating mang years as an example, the initial damagedetection and analysis for the main beam and the main linking members have been done bymeanings of the comprehensive bridge inspection technology. Based on the test results, firstly,using a model optimization correction method to establish the initial model of structure. Thenconsidering under the “great damage” condition, the local parameters of bridge change larger,the traditional correction method of the global variable parameters and the local parametercorrection method proposed in the paper are adopted respectively. The parametric models areestablished by ANSYS software and are corrected by using the first-order optimizationmethod. Comparing the results calculated by different methods with the experimental results,the shortage of some traditional methods on the structural variables settings are pointed out,that provides a reference for the actual project.(2) In the sensitivity analysis for each variable, considering that the common effects ofseveral similar low sensitivity variables on the model may be more than that some individualhigh sensitivity variables, it is recommended that the low sensitivity parameters should beabandoned with caution in the updating finite element model.(3) Introducing the reverse problem and the model correction method, based on the particle swarm optimization algorithm, the damage identification method is proposed. Tryingto combine MATLAB calculation files with ANSYS calculation files to achieve programmingmixedly, the updating finite element model for a structure is established, based on particleswarm optimization method. It is overcome that the calculation results may not be convergeddue to the morbid or strange gradient matrix in the traditional optimization algorithms. Thecredibility of the calculation results is improved. The method is suitable for practicalengineering applications.(4) Taking an actual bridge in the paper as an example, the critical locations damage ofthe main beam is identified be means of the updating finite element model based on thefirst-order optimization algorithm and the particle swarm optimization algorithm respectively.The two results are generally in agreement, that shows the proposed particle swarmoptimization algorithm is reasonable and effective. A new idea is proposed for the damagedetection and the condition assessment of the existing structure.(5) The advantages and disadvantages of the two damage identification method arecompared. It will take more time to calculate by the particle swarm optimization algorithm,but the possibility of the morbid optimization results will be avoided due to the sick or strangegradient matrix, thus the difficulties in the calculation of the large and complex structure canbe overcome. The first-order optimization algorithm from the ANSYS is relatively mature andmore suitable for the simple optimization analysis of the general engineering structure.In short, an objective and reliable optimization analysis for the existing bridge structurehas been done by means of the structural updating finite element method based on the particleswarm optimization algorithm. It can provide a reference for engineering practice.