FRP materials are currently used as reinforcement for concrete structures in which corrosion protection is a primary concern. FRP materials are corrosion-resistant and exhibit several properties that make them suitable for structural reinforcement. In a conventional structural system, joints are important part of the system, which transfer forces to the nearest members. Therefore, the present study is aimed at assessing the behavior of exterior RC beam-column joint reinforced with fiber reinforced polymer (the type of reinforcement) used, under static loading conditions. In this work, totally four exterior RC beam column joint specimens are casted. Two of them are reinforced with conventional steel and the remaining two are reinforced with GFRP rebars. These specimens are casted with no additional reinforcement at the joints. These specimens are tested under static loading conditions by keeping a constant load on the column and incremental load given on the beam. It is found that the load and moment carrying capacity of GFRP specimens are reduced by 20-30%. Cracks are initially developed at the beam-column joint interface and then further cracks are developed between the joint interface and loading point on the beam. The deflection of the beam is also higher for GFRP specimen compared to the control specimen.

In framed structures, failure often occurs at the beam-column junction due to the combined effect of bending moment and shear force. This makes the joint one of the most critical sections of the structure. Performance of the joint is evaluated on the basis of its strength and ductility. Considering the normal practice in a structural analysis to assume that the beam-column connection is rigid and also recognizing the importance of the beam-column connection for structural integrity, the beam-column connection must be provided with stiffness and of sufficient strength. Furthermore, reduction in stiffness due to the formation of diagonal cracks and local crushing of concrete may occur. Thus, failure of a beam-column connection must be precluded to preserve the structural integrity of members joined as rigid and strong as they are assumed in structural analysis. The essential requirements for satisfactory performance of the joints are: the service load performance of the joint should be equal to that of connecting members and the strength of the joint should not govern the strength of the structure. The behavior of joints is found to be dependent on a number of factors related to their geometry, amount and detailing of reinforcement, concrete strength and loading pattern.

Any joint in structural frame, designed to resist gravity and normal wind loads, falls into type 1 category that are designed on the basis of strength without considering special ductility requirements. Joints in framed structures designed to resist lateral loads due to earthquake, blast and cyclonic winds fall into type 2 category that are designed to have sustained strength under deformation reversals into inelastic range. Failure in a beam-column joint may occur because of the formation of plastic hinge in beam portion near the beam-column interface or formation of plastic hinge in column portion near the joint core or formation of diagonal crack in the joint region.

Structural Engineering Journal, Reinforced concrete, Beam-column joint, GFRP rebar, Moment, Failure mechanism