Structure Health Monitoring And Finite-Element Model Updating Of Yonghe Bridge After Retrofit

Recently, structural health monitoring (SHM) attracts many researchers interesting both domestic and foreign and becomes one of the most hot topics in civil engineering and disaster prevention and mitigation engineering. The structural health monitoring technology has been used in the engineering practice except for laboratory study gradually. Damage identification, finite-element model (FEM) updating and other related technology become the most important research field. How rational and effective use of recorded datum is the key of the health monitoring system.In this paper, FEM updating of YongHe bridge are studied. The main point are as follows:Firstly, The FEM of Yonghe Bridge is built based on the design drawings and the model is updated by FEM updating technology base on sensitivity analysis. Note that The direct pattern search algorithm is inefficient and often converges to the undifferential ridge lines. This paper presents a new adaptive pattern search algorithm, which makes use of the object function values obtained in the iterations. The algorithm has solved some of these problems, which indicates that the convergence is fast and can be guaranteed.Secondly, the adaptive search algorithm is programmed and several functions are studied in order to test its performance. Then, the algorithm is applied to model updating of Yonghe Bridge. The computing speed and convergence are compared with the artificial immune algorithm. The sensitivity of frequencies to some important parameters is studied.Thirdly, the monitoring data of dynamic subsystem is studied and the modal parameters of this bridge are identified using natural excitation technology and eigensystem realization algorithm. The results are compared with those of frequency domain decomposition with peaks pick method. Based on the measured modal data, baseline FEM model and adaptive pattern search algorithm, the real time FEM model updating is realized.At last, making use of the absolute measurement of Fiber Bragg Grating, this paper presents that the rebound strain can be measured in the drilling core sampling process of reinforcement concrete structures using FBG. The stress state of structure in service can be revealed according to the constitutive relationships of concrete material subjected to repeated load. FEM simulation and laboratory experiments have been done.