Title:
Shear Friction Performance of GFRP Headed-End Bars in Different Concrete Interfaces (Prepublished)
Author(s):
Mostafa M. Ahmed, Mohammed G. El-Gendy, and Ehab F. El-Salakawy
Publication:
Structural Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
cohesion; cold joint; composite construction; glass fiber-reinforced polymer (GFRP); headed-end bars; interface shear transfer; monolithic; roughness; shear friction
DOI:
10.14359/51751826
Date:
7/1/2026
Abstract:
Limited studies explored the shear friction behavior of reinforced concrete (RC) elements using glass fiber-reinforced polymer (GFRP), mostly using bent bars. This study investigates the behavior incorporating GFRP headed-end bars with varying reinforcement ratios and interface conditions. Twenty-one push-off specimens were tested to evaluate the influence of interface condition (i.e., as-cast, intentionally roughened, and monolithic joints), reinforcement type (i.e., steel stirrups, GFRP headed-end bars), and ratio (0.33 to 1.00%). The results revealed that interface condition and reinforcement stiffness significantly impact the behavior. Surface roughening slightly increased the capacity of the GFRP-RC specimens by 2 to 23%, while the monolithic GFRP-RC specimens reached peak loads up to 118% higher than the as-cast specimens. The GFRP-RC specimens exhibited significant load recovery, with secondary peak loads exceeding the first peak by up to 60%. Comparisons with existing models indicated that, in most cases, they inaccurately predict the capacities when GFRP connectors are utilized.