| Reinforced concrete beams that do not meet the required ultimate load carrying capacity are being strengthened using carbon fibre reinforced polymer (CFRP) laminates. Debonding of the laminate at or near the concrete/FRP interface has been identified as a possible flexural mode of failure. The design of the strengthening system generally avoids the debonding of the laminate at the ultimate limit state by requiring a sufficient anchorage zone. However, debonding at service load levels is possible due to poor installation, poor adhesive durability, or the presence of concrete cracking. Structural health monitoring (SHM) systems are installed to collect information about the structure in order to achieve a better understanding of its behaviour and can be used to detect the presence of damage. This thesis was an initial step in the determination of suitable damage indicators for use in a structural health monitoring system to detect laminate debonding damage. Theoretical and experimental work was conducted to assess two common damage detection techniques: strain sensing and vibration analysis. The strain results were found to be sensitive to the presence of induced debonded zones, although the presence of noise in the low level tests made positive damage identification difficult. Simple dynamic parameters were found not to be sensitive to the presence of the debonding damage. The influence of the debonding damage on the ultimate strength of the beams was also examined. |
