Browsing by Author "De Silva, WARK"

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    item: Conference-Abstract
    Detection and estimation of damage in framed structures using modal data
    De Silva, WARK; Lewangamage, CS; Jayasinghe, MTR
    The inevitable ageing and degradation of buildings and the structural failures that follow, have ignited a need for early prognosis of probable structural failures so that proactive measures can be undertaken. Hence, one of the important steps of structural health monitoring (SHM) process is the detection of damage location and estimation of damage severity. Modal data can be effectively used for this purpose owing to their sole dependency on mechanical characteristics of a structure. This study presents a damage detection methodology based on mode shape derivatives such as mode shape slope (MSS) and mode shape curvature (MSC) for a symmetric experimental steel frame model. Furthermore, an extended parametric analysis has been performed using a calibrated finite element model to investigate damage localization and quantify severity. The study provides key conclusions about the effect of boundaries on the damage detection method for the steel frame model. Furthermore, damage detection using MSC is identified to be more sensitive as opposed to MSS method.
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    item: Conference-Abstract
    Spot damage estimation of framed structures using modal data
    Bogahawaththa, PBMR; De Silva, WARK; Lewangamage, CS
    This study presents a modal-based damage detection technique for framed structures. A framed structure is tested using a vibration-based method and the mode shapes corresponding to undamaged and damaged states of the structure are obtained. The damage to the framed structure is induced by reducing the stiffness of columns at a particular storey and tested using the shaking table. The corresponding finite element (FE) model was verified for its natural frequency with the experimental model. Moreover, a series of studies were performed by concentrating the damage to a smaller scale by including spot damage on the framed structure and varying the damage location and intensity. The model was analysed using finite element software for these tests and mode shape slope differences and mode shape curvature differences were generated. Derivatives of mode shape slopes were plotted and correlated with the damage location. Mode shape slope is discontinuous and becomes a maximum value close to the damaged location. Mode shape curvatures also show a maximum difference near the damaged location. Finite element model, as well as the experimental investigation, shows the competence of the proposed approach in structural damage identification.