STRUCTURAL HEALTH, MONITORING VIA FLEXIBILITY UPDATE

Abstract

The study addresses the issue of identification of modal characteristics of a framed build-ing structure from its earthquake response data and its subsequent application in struc-tural health monitoring using vibration-based damage detection methods. The damages due to earthquake excitations are simulated in beams of an analytical model of a seven storey reinforced concrete (RC) structure, pertaining to strong column-weak beam philos-ophy of earthquake resistant design. Time domain interpolated signals are synthesized at the degrees of freedom (dofs) where the recorded data are not available to get by the practical problem of limited number of sensors. The undamaged properties of the structure are extracted from the earthquake response data itself, eradicating the need of tedious job of exact modeling of the actual structure. The methods implemented in the study for system identification are frequency domain decomposition (FDD), empir-ical transfer function estimate (ETFE), and time domain decomposition (TDD). The FDD and ETFE methods give a good estimated of frequencies while TDD method yields mode shapes incisively. A time windowing approach is adopted for damage detection. The flexibility method is successfully able to identify beam damages in the structure, but fails to locate the damages. The mode curvature method is found to be fairly precise in identifying the location of damages