An innovative two-stage damage detection method for space latticed structures

Abstract

Large span space latticed structures are widely used in public building structures. They inevitably suffer from damage attack during service process, which may weaken the mechanical properties of the structure. Therefore, it is necessary to conduct damage identification for these structures which can help evaluate their damage status. Because the structure form of space latticed structures differs from that of high-rise building and frame structures and number of members in large span space latticed structures are extremely numerous, there is short of an efficient and effective damage identification method that can be applicable to large span space latticed structures. In this case, an improved damage positioning method based on residual modal force is first developed, in which a weighting factor is assigned to the residual modal force of each modal order to impair the noise-induced effect on damage positioning. The effect of different modal expansion methods on this improved damage positioning method are investigated. It is found that kinetic condensation method is more preferable. Redundant undamaged members can thus be excluded in advance using this method, based on which an improved cross-model cross-mode (CMCM) method is developed for determining damage coefficients. Furthermore, an GA algorithm based optimal sensor placement method that can balance the improvement of the signal-to-noise ratio and the orthogonality condition for identified post-damage modal shapes is proposed, by which a more preferable damage identification effect is achieved. Finally, effect of critical parameters, i.e., number of post-damage and pre-damage modal orders, on the developed two-stage damage identification method is discussed.