Title:
Interface Shear between Ordinary Concrete and UHPC with GFRP Reinforcing Bars (Prepublished)
Author(s):
Yail J. Kim and Ali Alatify
Publication:
Structural Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
dowel action; glass fiber-reinforced polymer (GFRP) reinforcement; interface resistance; ultra-high-performance concrete (UHPC)
DOI:
10.14359/51749317
Date:
11/12/2025
Abstract:
This paper presents the interface shear between ordinary concrete and ultra-high-performance concrete (UHPC) connected with glass fiber-reinforced polymer (GFRP) reinforcing bars. Following ancillary tests on reinforcing bar fracture under in-plane shear loading, concrete-reinforcing bar assemblies are loaded to examine capacities and failure modes as influenced by the size, spacing, and number of the reinforcing bars. While the shear behavior of bare reinforcing bars is primarily governed by the orientation of the load-resisting axes in the glass fibers and their volume, the size and spacing of the reinforcement largely control the interface capacity by affecting the load-transfer mechanism from the reinforcing bar to the concrete. The degree of stress distribution affects the load-displacement response of the interface, which is characterized in terms of quasi-steady, kinetic, and failure regions. The primary failure modes of the interface comprise rebar rupture and concrete splitting. The formation of cracks between the ordinary concrete and UHPC results from interfacial deformations, leading to spalling damage when applied loads exceed service levels. An analytical model is formulated alongside an optimization technique. The capacities of the interface in relation to the reinforcing bar rupture and concrete splitting failure modes are predicted. Furthermore, a machine learning algorithm is used to define a failure envelope and propose practice guidelines through parametric investigations.