DAMAGE ASSESSMENT OF CORRODED REINFORCED CONCRETE BEAMS USING MODAL TESTING

摘要

A laboratory investigation to study the effect of general corrosion on the modal parameters of reinforced concrete beams was conducted. Full scale beams were subjected to reinforcement corrosion until an appreciable amount of steel corrosion damage was introduced using an accelerated technique namely galvanostatic method. The states of damage in the test beams were assessed through measurement of crack width, loss of area and half-cell potential. Modal tests were performed on the test beams after corrosion damage and the modal parameters extracted were compared against that from control beams. The results obtained showed changes in the modal parameters especially natural frequencies and mode shapes. The intensity of the drop in the measured natural frequencies was sensitive to the deterioration state of the beams. Hence, changes in natural frequencies could be established as a damage indicator, which relate to the loss in flexural stiffness of the corroded beams. Using modal assurance techniques to perform orthogonality checks on sets of mode shape from the control and corroded beams, changes could be visualised which were dependant on the degree of corrosion damage induced. Finally, the load carrying capacity of the beams were determined through static load test and the results were correlated with the state of corrosion damage and changes in the modal parameters. This investigation provided further insight on the use of modal parameters to detect and assess damage in structural concrete elements, which can be useful for structural appraisal purposes when applied to full scale structures.