Evaluation of fiber reinforced polymer bars under compression: experiments and finite element simulations

A Master of Science thesis in Civil Engineering by Laith Abdul-Qader Said Al Najmi entitled, “Evaluation of fiber reinforced polymer bars under compression: experiments and finite element simulations”, submitted in November 2020. Thesis advisor is Dr. Farid Abed. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).

Abstract

The behavior of Fiber-reinforced polymers (FRP) bars under compression is not fully understood yet due to the limited research in this area; therefore, American concrete institute (ACI) does not recommend using FRP bars in compression. However, the long-term durability, weathering resistance, and exceptional mechanical properties of FRP bars justify the need for their use in compression members. The main objectives of this study are to evaluate the mechanical properties of Glass FRP (GFRP) and Basalt FRP (BFRP) bars under compression and examine their performance as main longitudinal reinforcement in reinforced concrete columns. In the first part of this research, a series of static tests were conducted on GFRP and BFRP specimens of different diameters. Steel grips filled with epoxy were used at the top and bottom surfaces of the FRP bar to avoid premature failure at the ends and ensure pure compression. The second part of this research numerically investigated the behavior of FRP-RC columns under concentric and eccentric loading using the mechanical properties of FRP bars obtained experimentally. For this purpose, nonlinear finite element models were developed and verified using the experimental results conducted previously at the AUS construction lab. The verified FE models were then utilized to conduct a parametric analysis to simulate the compressive behavior of concrete columns reinforced with GFRP and BFRP bars. Interaction diagrams were also developed based on the FE analysis considering different design parameters such as the cross-section of the column, type and ratio of longitudinal and lateral reinforcement, and loading eccentricities.