Reinforced concrete structures such as slabs-on-ground develop cracks due to drying shrinkage and thermal loading before concentrated vehicle loads are applied to them. These cracks are conduits for ingress of chloride, leading to corrosion of the steel and damage to the slabs. Grade supported slabs reinforced with non-corroding GFRP bars are an attractive alternative that could provide a maintenance free service life of over 100 years. The punching shear capacity of GFRP bars reinforced slabs-on-ground, which are primarily designed to control shrinkage and crack width, has not been investigated in the literature. This paper presents the results of numerical parametric studies conducted to investigate the performance of grade supported slabs reinforced with GFRP bars. The numerical model developed in the study was calibrated using data obtained from punching shear failure tests performed on the slabs by the authors. After validation of the numerical model, parametric studies were performed to investigate the effects of variables such as concrete strength, reinforcement ratio, and rebar grid location in the slab. Guidelines for the design of GFRP bar reinforcement for slabs-on-grade are provided.
Ground-supported structures such as slabs-on-ground, walkways, concrete pavements, storm-water channels, pipe supports, and industrial floors are exposed to harsh environmental conditions in the Middle East region, characterized by large temperature and humidity fluctuations. The highly varying temperature and humidity regimes accelerates moisture diffusion and the associated drying shrinkage in concrete slabs. The external restraint on these slabs by the subgrade and the internal restraint from the embedded reinforcement causes cracks on the surface of these slabs. These cracks provide the alleyways for easy ingress of salt and other chemicals from the environment and lead to corrosion of the steel reinforcements. Glass fiber reinforced polymer (GFRP) bars have emerged as a potential non-metallic reinforcement that can replace steel bars. They are lightweight, corrosion resistant, have high tensile strength, and are electrically transparent (1). In recent years, there has been a surge in the application of GFRP bars in various concrete structures worldwide because they have favorable properties and provide long durability, despite their higher initial cost. The Arabian American Oil Company (Aramco) has mandated the use of GFRP bars in grade-supported concrete structures. Recently, several new codes, standards and guidelines have been developed for the design of concrete structures using GFRP bars, including ACI 440.11-22 (2), AASHTO LRFD (3), and ACI 440.1R-15 (4). The 21.3-km long flood water mitigation channel in Jazan, Saudi Arabia, is the first major application of GFRP bars in grade supported concrete structures using over 10 million linear meters of GFRP bars. It is expected to have a service life of over 100 years with low life-cycle costs (5,6).
