Damage detection based on strain output feedback of the bridges under active excitation

Most of damage diagnosis methods for actual bridges belong to the open-loop technique, i.e., there is no feedback between the input and output of structures. Although many research achievements have been acquired, this type of methods has encountered a dilemma in mining the structural features that are sensitive to the damage of structures. To address this issue, a close-loop damage diagnosis method is proposed by applying the specific active excitation to the superstructure of bridges, which obtain the features with high sensitivity to damage of bridges. Considering the observability condition of system, a certain number of measured DOFs (degree of freedom) of structural response are necessary, which sometimes is difficult to be realized for the actual condition. Aiming at this issue, the structural strain of superstructure of bridge, obtained by using the distributed BOTDA (Brillouin optical time domain analysis), are applied to be the output feedback of the proposed method since the high spatial resolution of measured points supplied by BOTDA technique can ensure the sufficient measured DOFs of response of bridges. Finally, the effectiveness of the proposed method is proved by using the numerical examples.