Flexural behavior of novel hybrid multicell GFRP-concrete beam

A novel hybrid beam consisting of pultruded GFRP three-cell box-section and concrete slab was proposed for pedestrian bridges. The flexural behavior of the proposed beam was investigated through experimental and analytical studies. First, material characterization tests were conducted to evaluate the mechanical properties of the GFRP material. Second, four- and three-point bending tests were carried out on four beams with varying span lengths. The flexural and shear stiffness of the beams were calculated and evaluated based on the experimental results. Design equations were proposed to predict the ultimate flexural strength of the hybrid beam. Finite element (FE) models were constructed to validate the effectiveness of the proposed hybrid beam. A good correlation was found between the experimental results, the analytical predictions from the proposed design equation, and the numerical results from FE modeling. The combined bolted and bonded connection provided effective shear transfer between GFRP and concrete, ensuring a good composite action of the hybrid beam. Additionally, the proposed three-cell box-beam increased the web local buckling strength of GFRP beams subjected to a concentrated load, avoiding the premature buckling failure of the entire beam. The proposed hybrid GFRP-concrete beam provides an effective approach to increase the span length of GFRP structures.