On the Tensile Capacity of Single-bolted Connections between GFRP Angles and Gusset Plates-Testing and Modelling

The polymer composite known as Glass Fibre Reinforced Polymer (GFRP) has several advantages over conventional materials. It has been slowly incorporated into civil infrastructures. Because of lack of knowledge about the behaviour and design criteria of structural connections, the wide-spread application of GFRP in this field has been rather limited. In this study, analytical and experimental behaviour of GFRP structural angle members with gusset plate connections for net-tension strength, with an emphasis on transmission line tower connections, were investigated. Thirty-five single-lap, single-bolted connections were tested. The widths of the gusset plate and edge distance were varied. A tensile load was applied on the joint and then failure modes and the corresponding loads were observed. The effect of the plate width and edge distance on the connection efficiency was also studied. Based on the studies, the optimum plate width and edge distance were determined as three and five times diameter of the bolt, respectively. A semi-empirical analytical stress concentration model proposed by Hart-Smith (1978), is adopted to determine the cross-correlation coefficient 'C' which is linearly correlated to the stress concentration factors of composite and elastic isotropic materials. Using regression analysis, the coefficient 'C' was obtained, and an ultimate net-tension strength design formula is proposed.