Structural Behavior of BFRCC Layered Deep Beams Reinforced with GFRP Headed-End Bars: Fid-Bau Portal

Structural Behavior of BFRCC Layered Deep Beams Reinforced with GFRP Headed-End Bars

Bediwy, Ahmed / Mahmoud, Karam / El-Salakawy, Ehab

In North America, structures in aggressive environments such as bridges and parking structures are prime examples for the use of fiber-reinforced composites (FRCs) due to their capability to control shrinkage cracking and improve impact resistance. Also, after cracking, more advantages of FRCs were reported such as increased energy-absorbing capacity and deformation capability, and improved load-bearing capacity. Reinforced concrete (RC) deep beams are one of the common components in such structures. Deep beams have higher load capacity compared to slender beams. They are characterized by their small span-to-depth ratio and they are usually designed using the Strut-and-Tie Model (STM). Recently, fiber-reinforced polymer (FRP) bars have been used as an alternative to steel bars to overcome the corrosion problems. However, due to its linear-elastic behavior and relatively low modulus of elasticity compared to steel, glass FRP (GFRP)-RC deep beams would be susceptible to deeper and wider cracks as well as lack of ability to redistribute stresses, which will adversely affect the capacity of such beams. On the other hand, contribution of the arch action mechanism to the shear strength in FRP-RC deep beams can be improved because of the relatively higher tensile strength of FRP bars in the tie.

In this study, a layer of basalt fiber-reinforced cementitious composite (BFRCC) was incorporated in the tie zone to examine its ability to enhance the overall behavior of GFRP-RC deep beams. Two large-scale RC deep beams reinforced with GFRP headed-end bars were constructed and tested up to failure. The specimens had a rectangular section of 250 × 590 mm and a length of 2,100 mm. The main variable was the incorporation of the BFRCC layer in the tie zone. The specimens were tested in a three-point bending setup over a clear span of 1.24 m with a shear span-to-depth ratio of 1.0. The test results confirmed the formation of the arch action mechanism in both beams. In addition, analysis of test results pinpoints that the incorporation of basalt fiber pellets in the tie zone of the beam improved its behavior and increased its load carrying capacity.