Model updating of Nanzhonghuan Bridge based on improved gravitational search algorithm

Here, to obtain the benchmark finite element model of Nanzhonghuan bridge, Kriging model and the improved gravitational search algorithm (GSA) were combined to modify the initial finite element model using load test data. Firstly, the basic principles of Kriging model and GSA were described. The random crossover mutation method was introduced into the basic GSA to propose the improved GSA, it was verified with the testing function. Then, Nanzhonghuan bridge's project brief situation, load test content and its initial finite element model were introduced. Furthermore, 6 parameters to be modified were selected, frequency and displacement samples corresponding to parameters to be modified were obtained through test design, and Kriging model was established to predict the structure's responses. Finally, taking the residual of test value and calculated value of frequency and displacement as the objective function, the improved GSA, particle swarm optimization (PSO) and GSA algorithms were used, respectively to search the minimum value of the objective function in the design space of parameters to be modified and the modified results were contrastively analyzed. The results showed that the improved GSA has better stability and higher accuracy for the testing function; through model updating, relative errors of frequency and displacement are significantly reduced except for few measured points; compared with PSO and GSA, the improved GSA can get smaller objective function value, relative errors of frequency and displacement after model updating are smaller. © 2021, Editorial Office of Journal of Vibration and Shock. All right reserved.