Shear behaviour of the post-tensioned segmental precast concrete pontoon deck with the GFRP rods

The present experimental and numerical study evaluated the structural performance of segmental concrete pontoon decks reinforced and post-tensioned with GFRP rods. Four large-scale decks were tested and the load-displacement response, strain behaviour of rods, concrete, and failure mechanism in four different prestressing levels were assessed. It was found that a small post-tensioning of 7.4 % of the rod's ultimate tensile strength reduced the self-weight deflection by 92 % and increased initial stiffness by 8.7 times compared to segmental decks without prestressing. Failure in prestressing decks typically began with concrete crushing at the joint with an increased compression depth due to increased initial post-tension; however, the ultimate failure mechanism of the hand-tight deck was governed by the interlaminar shear of the rod. A finite element model was developed and verified against test results A parametric study evaluating the influence of the post-tensioning at higher load, rod depth, concrete properties, rod number, and deck geometry was implemented. It was shown that increasing the post-tension load and depth of the rod improved the stiffness and reducing the spacing can result in a more uniform compression stress in the joint. This study provides design recommendations for ACI 440.4 R-04, by considering the concrete compression depth between joints rather than the depth of the FRP rod and contributes to a more accurate load estimation of the concrete crushing caused by joint openings. The results of this research could rectify the present problems with the construction design of maritime infrastructure and offer an innovative solution.