基于模态参数考虑边界条件变异的桥梁结构损伤识别

ccording to the engineering characteristic of bridge structure, boundary condition variation and structure damages as well as the parameterization of them were detailed analyzed. The optimization inversion question was established with target function of minimum sum of square errors between mode parameters tested and calculated by using constrained optimization theory. The first and second order eigen-value and eigen-vector of the corresponding dynamic equation were introduced into the optimization inversion question based on matrix perturbation theory, so the question was simplified into optimization inversion of the nonlinear least square. According to the fact that boundary condition of bridge structure has much more effect on mode parameters, pre-identification of boundary condition was used. Then the detailed method and process of bridge structure damage detection were put forward accounting for the boundary condition, in which pre-location method of element mode strain energy was adopted. At last, the numerical analysis results of a maglev railway girder shows that the damage detection method can effectively detect change of boundary condition and structure damage with fairly well precision.