GFRP-REINFORCED CONCRETE BEAM-COLUMN JOINTS M. Hasaballa, M. Mady, A. El-Ragaby, and E.F. El-Salakawy Canada Research Chair in Advanced Composite Materials and Monitoring of Civil Infrastructures Department of Civil Engineering, University of Manitoba, Winnipeg, Manitoba, Canada. Email: Ehab_Elsalakawy@Umanitoba.ca ABSTRACT A significant amount of research has been conducted on individual fibre reinforced polymer reinforced concrete (FRP-RC) structural elements such as beams, slabs, and recently columns, which have shown considerable inelasticity or deformability under monotonic and fatigue loading. However, the behaviour of FRP bars in tension-compression reversals in FRP-RC columns and frame structures has not been investigated yet. Furthermore, the elastic-linear behaviour of the FRP material up to failure is raising concerns on the ability to dissipate energy of frame structures in seismic loading events. Therefore, this research project aims to investigate the feasibility of using FRP reinforcement in such structural elements. A total of four full-scale exterior T-shaped beam-column joint prototypes are constructed and tested under simulated seismic load conditions. The beam measures 2100 mm long, 350 mm wide and 450 mm deep, while the column measures 3650 mm long with a 350 mm square section. Reversal lateral quasi-static cyclic loads are applied directly at the beam tip simulating seismic loading. This paper is focusing on the test results and analysis of two test prototypes. One prototype is totally reinforced with glass FRP bars and stirrups, while the other one is reinforced with steel. The experimental results showed that the joint drift capacity can reach more than 3.0% safely without any considerable damage, which indicates the validity of using glass FRP bars and stirrups as reinforcement in the beam-column joints subjected to seismic-type loading. KEYWORDS Glass FRP, Stirrups, RC frames, Seismic design, Beam-column joints. INTRODUCTION During a strong earthquake, beam-column joints are subjected to severe reversed cyclic loading. If not designed and detailed properly, the performance of these joints can significantly affect the overall response of a ductile moment-resisting frame building. The design philosophy of such frames is based on providing sufficient ductility to the structure to dissipate the seismic energy by means of inelastic rotations. Extensive research in steel- reinforced concrete frames showed that the inelastic rotations spread over specific regions defined as plastic hinges. During these inelastic deformations, concrete and steel properties are beyond the elastic range. Ductile RC frames are designed based on the concept of strong column-weak beam, where plastic hinges are allowed to form within beams, not the columns (Hanson and Connor 1967). The main function of the joint is to enable the adjoining members to develop and sustain their ultimate capacity. Such design requires that the beam-column joints should be capable of withstanding several inelastic load reversals at the beam plastic hinge without significant loss of strength and energy dissipating ability. Beam-column joints also should have limited deformations in order not to affect the column designed capacity or increase the storey horizontal drift (ACI- ASCE Committee 352 2002). On the other hand, the corrosion problem of steel reinforcing bars is a major factor in limiting the life expectancy of reinforced concrete structures. In some cases, the repair cost can be twice as high as the original one (Yunovich and Thompson 2003). The fibre reinforced polymer (FRP) reinforcement is currently being used as a construction material in new concrete structures especially those in harsh environments such as parking garages and bridges. The main driving force behind this effort is the superior performance of FRP in corrosive environments due to its non-corrodible nature. However, the FRP material exhibits linear-elastic stress-strain characteristics up to failure with relatively low modulus of elasticity (40-50 GPa for glass FRP and 110-140 MPa for carbon FRP compared to 200 GPa for steel). Moreover, they have different bond characteristics and low strength under compression. These mechanical and physical properties of FRP materials make the behaviour and 337