Experimental and analytical investigations on the torsional behaviour of glass fibre - reinforced concretepontoon decks

Experimental and analytical investigations on the torsional behaviour of glass fibre - reinforced concretepontoon decks

This comprehensive research delves into the use of glass fibre - reinforced polymer (GFRP) bars as internal reinforcements in concrete pontoon decks, particularly in marine environments, to counter the corrosion issues of traditional steel reinforcements. Recognizing the gap in understanding the torsional behaviour of GFRP-reinforced structures, the study systematically investigates their response, especially under wave-induced torsional loads. Key findings from the first part of the study reveal that factors such as edge cutout, bar distribution, and rotation direction influence the torsional capacity and failure behaviour of GFRP-reinforced concrete structures (GFRP-RC) pontoon decks. Notably, double-layer reinforcement demonstrates better control over crack growth post-cracking compared to single-layer reinforcement, and edge cutout reduce cracking torque by around 17%. The study also finds that the ACI 318-19 equation accurately predicts the decks' torsional behaviour during the cracking stage. Further investigation highlights the role of diagonal bars, reinforcement arrangement, and grid spacing. It shows that diagonal reinforcements in double-layer setups and denser grids considerably improve both pre- and post-cracking torsional behaviour, with some configurations matching the torsional resistance of solid decks. The third research includes extensive finite element (FE) analyses validated by large-scale laboratory tests, covering aspects like concrete strength, cutout geometry, and reinforcement configurations. These analyses underscore the critical impact of concrete strength and reinforcement configuration on torsional behaviour, while the influence of cutout geometry is less pronounced. Predictive equations developed for torsional rigidity and cracking torque show a good correlation with FE results. Overall, this study offers vital insights for the design and optimization of GFRP-reinforced concrete pontoon decks, emphasizing the importance of strategic reinforcement configurations and deck geometries. These findings are crucial for enhancing the structural integrity and durability of such decks against the challenges posed by wave-induced torsion.

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