Structural Damage Diagnosis Of Medium And Small Span Bridges Based On Active Excitation Technique

In our country,the small and medium span bridges occupy a large proportion in total amount of bridges.Aiming at solving the problem of the rapid structural damage diagnosis on such type of bridges,this paper presents a structural damage diagnosis method based on active excitation technique.By applying specific active excitation to the structure of bridge,the high sensitivity eigen information of local damage can be obtained to diagnose the structural damage rapidly and accurately.The eigenvalue sensitivity calculation method of closed loop structure system is studied systematically by focusing on pole assignment.Firstly,the gain matrix of closed loop structure system with high damage sensitivity is constructed by taking advantage of the full-state feedback information;secondly,the structural damage diagnosis of bridges based on full-state feedback can be realized by feedback.Finally,the application possibility of full-state feedback is discussed.The damage diagnosis of bridge structures based on output feedback is discussed in detail.The feedback gain and active excitation determination method based on output feedback are explored under constructed constraints to ensure the stability of closed loop system;aiming at researching the applicability,effectiveness and robustness of the damage diagnosis method based on output feedback,a numerical bridge model is investigated and analyzed.On the basis of the above research,the damage diagnosis of bridge structures based on output strain feedback is mainly studied under active excitation.Firstly,the strain response of the girder bridge with high spatial resolution is obtained by continuous distributed Brillouin optical fiber sensing technique,which helps computes the displacement response by the transformation relationship between strain and displacement,and then the method of active excitation determination of the closed loop structure system based on output strain feedback is proposed;secondly,the damage diagnosis of bridge structure based on output strain feedback is realized by regard the close loop eigenvalue as the damage index;finally,the effectiveness of the proposed algorithm is verified by numerical simulation.