Study On The Optimized Layout Of Accelerometers For Obtaining Modes Of Cable-stayed Bridges

In recent years, the optimized layout of accelerometers which is animportant component of bridge health monitoring system, has become a researchemphasis. However, many optimization theories of accelerometer layout such asthe effective independence, modal assurance criterion and modal strain energycriterion etc have been presented, however they still stay on the stage oftheoretical analysis and finite element simulation and have not been verified byfield test.Firstly, by using the universal finite element program ANSYS, the finiteelement model of Zhang Zhen cable-stayed bridge which locates in Shang YuCounty of Zhe Jiang province is established, the first fifty vibration modes andtheir natural frequencies are obtained by dynamic characteristics analysis. Basedon the analyzed modes, the vertical and lateral acceleration sensor optimizationscheme of Zhang Zhen cable-stayed bridge is determined by using acomputational procedure which is programmed with MATLAB language, anduses MAC modal assurance criterion as the objective function and the simulatedannealing algorithm for sensor optimization.Then, the obtained optimization scheme of accelerometer layout throughusing the simulated annealing algorithm is applied to Zhang Zhen cable-stayedbridge, and the acceleration time histories of each measuring points wereobtained from field test of bridge dynamic performance. Through the powerspectrum analysis, the practical modes and their natural frequencies of ZhangZhen cable-stayed bridge are obtained.Finally, through comparing the measured natural frequencies and modeswith those of ANSYS, it is found that they are very identical. Therefore, it isverified to be effective for using the simulated annealing algorithm and modalconfidence criterion theory for the optimization layout of accelerometers, in turn,and the ANSYS finite element model of Zhang Zhen cable-stayed bridge is also proved to be accurate.