Modelling of Reinforced Concrete Columns with GFRP Rebar

Concrete structures reinforced with glass fiber-reinforced polymer (GFRP) bars are becoming increasingly popular, particularly in harsh environments where traditional steel reinforcement may be susceptible to corrosion and accelerated damage. GFRPs are a possible solution in such climates, since they are not affected by corrosion and have high tensile strength. The assessment of GFRP-reinforced concrete structural response to lateral loads, however, is still in a preliminary stage. Despite the need for robust numerical tools to estimate the lateral displacement and ductility capacities of GFRP-reinforced structural elements, current numerical modeling is limited by the lack of reliable full-range axial stress vs strain models, or by insufficient description of the behavior of GFRP-confined concrete. This paper aims at providing a contribution to the analytical modeling of the response to lateral loads of GFRP-reinforced concrete elements. Four scaled RC bridge columns have been designed (with the same nominal strength) and built for testing to failure under simulated earthquake loading at San Diego State University (SDSU), with various combinations of steel and GFRP bars, from all-steel to all-GFRP. In this work, GFRP reinforcement is considered for both the primary vertical and transverse reinforcements. Prediction analyses of the four different columns to failure are discussed in this paper, including a technique of incremental confinement which is crucial for concrete confined by GFRP.