Simulation of Concrete Beams Strengthened by Embedded Through-section Steel and GFRP Bars with Newly Developed Bond Model

This paper presents an experimental and numerical investigation on concrete members strengthened by embedded through-section (ETS) steel and glass fiber-reinforced polymer (GFRP) bars attached preferably with mechanical anchorage at the tension ends. The pullout tests to analyze the bond performance between ETS bars and concrete under various influences such as anchorage presence, embedment length, ETS bar diameter, ETS-material types, and anchorage length are carried out. An analytical method for deriving the local bond stress-slip relationship of GFRP bars-concrete interfaces is developed. The overall responses of the pullout test specimens in terms of pullout force-slip curves, failure modes and strain profiles along the embedment length are discussed. Based on a careful interpretation, the analytical results demonstrated the effectiveness of the local bond stress-slip model developed in this study. Additionally, the finite element (FE) simulation of the beams intervened with ETS bars, which were tested in a previous study by the authors, incorporating with the proposed interfacial model is conducted. Comparison between the results achieved from the FE modelling and the experiment implies that the FE method was an accurately applicable tool to assess the behaviors of the beams strengthened in shear by ETS bars.