Deformation-Based Design of Hollow Coarse-Aggregate Ultra-High-Performance-Concrete Beams Reinforced with Cfrp Bars

Abstract

This study aims to develop a novel type of beams strengthened with carbon fiber-reinforced polymer (CFRP) bars and cast using ultra-high-performance concrete (UHPC) with coarse aggregates (CA-UHPC) to address issues such as poor ductility, extensive cracking, and significant deflection observed in FRP-reinforced concrete (FRP-RC) beams. Furthermore, the deformation behaviors of CFRP-CA-UHPC beams with different hollow shapes and ratios are investigated to fully leverage the material's strength. To this end, six hollow beams are fabricated and subjected to cyclic loading via a four-point-bending test. The results show that the deformation of all hollow beams under service loads adheres to the deformation limits specified in the GB50610 code. The hollow ratio had a negative impact on the flexural behaviors of beams, and this effect was more pronounced in beams with higher hollow ratios than in that with lower hollow ratios. The flexural performances of square hollow beams are better than that of circular hollow beams with the same hollow ratio. Compared to other hollow beams, square hollow beams with a hollow ratio of 44.44% demonstrated superior flexural performance and optimal cost-effectiveness. Ultimately, leveraging the computational framework for steel fiber reinforcement and residual deflection, predictive models for deflection were formulated for CFRP-CA-UHPC beams with various hollow configurations under both static and cyclic loading conditions.

Keywords: Ultra-high-performance concrete with coarse aggregate (CA-UHPC), Carbon fibre, Deformation behaviors