Abstract: Structural flexibility matrix and element’s stiffness matrix are difficult be obtained accurately by sensitivity analysis of structural flexibility in practical vibration test.To solve this problem, an improved method which optimizes and reduces input data to meet the requirements of practical application is proposed. The first several low modals are collected and the structural flexibility matrix is calculated, and then the elements are assumed successively to be damaged and the matrix of flexibility variation before and after structural damage is built. The method is applied to the damage identification for a hydraulic radial gate, and the numerical simulation results prove that the proposed method could locate the damaged element accurately and avoid the misjudgment of symmetric unit. The research provides theoretical basis for the damage identification of hydraulic structures.

Key words: radial gate, flexibility sensitivity, damage identification, modal parameter, flexibility matrix