Distributed Sensing to Assess the Behaviour of Dynamically Loaded Reinforced Concrete Beams
The assessment of reinforced concrete (RC) structures has been inherently limited by the lack of adequate sensing technologies, which can capture both the global and localized behaviour of these complex composite systems. The inability to properly assess these structures, and understand their behaviour under static and dynamic loads, can result in costly rehabilitation or replacement of existing structures and potentially unnecessary conservativeness in future designs. To improve on traditional assessment methods, this thesis investigates the application of a new fibre optic sensing system, which is capable of accurately measuring dynamic and distributed strains throughout the length of a fibre optic cable. An experimental campaign was conducted, which included the design, construction and testing of 4 slender and 4 deep RC beams. The purpose of these tests was to evaluate the durability and accuracy of dynamic distributed fibre optic sensors (DDFOS) under dynamic loading, as well as to utilize the DDFOS results to develop a better understanding of the behaviour of RC beams under both cyclic and ultimate loads. The results showed that the fibre optic sensors could withstand the repeated loading as well as ultimate loads while accurately measuring distributed strains along the steel reinforcement within the RC specimens. This data provided key insights into the change of load carrying mechanism (from beam action to arch action) as well as the failure mechanisms. Two case studies were also conducted on existing RC beams within a building. The studies included the in-situ dynamic loading of the beams while monitoring them with both DDFOS technology and tradition discrete sensors. Jumping tests were carried out to provide dynamic loading on each beam. The detailed DDFOS data was assessed by comparing the results to the traditional sensors, and was used to determine critical performance metrics of the RC beams including: maximum strains, support conditions, and cracking behaviour. The data was further used to provide dynamic estimations of the changing distributed deflections and crack widths due to the application of the dynamic loads.