Structural health monitoring of civil infrastructure using modal flexibility matrix

Abstract

The modal flexibility-based damage detection approach has recently become a promising damage de-scriptor due to its reliable and practical potential for real applications. This study aims to develop and improve the modal flexibility-based damage detection approach for civil infrastructure. Firstly, a new damage detection approach for multi-story buildings was developed using the damage-induced inter-story deflection (DIID) estimated by modal flexibility. This study intends to provide a basis for the damage detection problem of more complex multi-story buildings by investigating rather idealized structures such as a shear-dominant multi-story building and a bending-dominant multi-story building. Since the DIID oc-curs at a damaged location, computing the abrupt appearance in DIID set is central to the approach. This ap-proach has a clear theoretical base and directly identifies multiple damage locations as well as a single damage location without the use of a finite element (FE) model. For validating the applicability of the proposed approach to multi-story buildings, a series of numerical and experimental studies on shear-dominant buildings (i.e., a lab-scale 5-story shear-dominant building model and a full-scale 5-story shear-dominant building) and a 10-story bending-dominant building model were carried out. From those various tests, it was found that the damage locations can be successfully identified by the proposed approach for multiple damages as well as single damage. In order to confirm the superiority of the proposed approach, comparative study was carried out on two well-known damage metrics such as modal strain-based damage index approach and uniform load surface curvature approach. Conventional modal flexibility-based damage detection approaches using acceleration measurements have limitations in damage detection near the bridge support, since damage metric estimated from acceleration measurements is insensitive to damage near the bridge support an...