Numerical study of structural joints reinforced with composite fabrics

The structural application of composite materials such as fiber reinforced plastics (FRP) has increased in recent years. The FRP products can be used in the initial construction or for repair and structural enhancement. FRP materials have several advantages over steel including, light weight, corrosion resistance, and the ability to mold FRP overlays to concrete surfaces. FRP overlays have been used to strengthen/repair both concrete beam and column elements. Limited studies have been performed on the use of FRP overlays at beam-column connections. Joints that are reinforced with FRP overlays have a different failure mode than FRP plated beams or wrapped columns. At the beam-column connection the interface is subjected to prying or peeling stresses. This investigation involves parametric studies of the application of FRP overlays to exterior beam-column connections for enhancement of structural performance. Different composite materials and different overlay configurations are used. The choice of the composite materials affects the structural performance. Materials that are considered are "E"-glass, kevlar, and graphite. Configurations studied include overlays bonded to the tensile faces with and without wraps. Numerical analysis shows that the bond stress perpendicular to the overlay/concrete interface at the beam-column junction can easily exceed the tensile strength of the underlying concrete. Therefore, the configuration of the FRP overlay plays an important role in the prevention of peeling.