Finite Element Modeling of GFRP Bar-Reinforced Hollow-Core Concrete Beams Under Flexural Loads

Hollow core concrete beams offer advantages such as reduced weight, material efficiency, improved thermal and acoustic insulation, better fire resistance, and faster construction. Traditionally, steel-reinforced hollow core slabs have been widely used in precast construction. However, glass fiber-reinforced polymer (GFRP) bars are gaining attention as a corrosion-resistant, lightweight alternative to steel reinforcement in concrete structures. This study investigates the flexural performance of hollow-core concrete beams reinforced with GFRP bars using nonlinear finite element (FE) simulations. FE models, validated against experimental data from seven beams (220 × 300 × 2000 mm³), accurately replicated load–displacement responses, crack patterns, and failure modes. Parametric studies explored factors such as hole location, size, shape, reinforcement ratio, and shear span-to-depth ratio. Results showed that beams with centrally located longitudinal holes had higher cracking and ultimate loads, while circular holes performed better than square or rectangular ones. Increasing hole dimensions reduced load capacities, and deeper beams showed greater reduction in cracking load. Enhancing the GFRP reinforcement ratio significantly improved flexural strength. The models predicted ultimate capacity with a margin of less than 7% difference from experimental results.