PSI - Issue 70

R. Krishnasamy et al. / Procedia Structural Integrity 70 (2025) 343–349

344

1. Introduction Glass Fiber Reinforced Polymer (GFRP) angle members are gaining attention as a viable alternative to traditional materials like steel in transmission line towers. These composite materials offer several advantages, including a high strength-to-weight ratio, excellent corrosion resistance, and ease of handling and installation. The connection behavior of GFRP angle members is a critical aspect of their structural performance, as these connections are subjected to varying tensile and compressive forces due to environmental factors like wind loads. Research in this area focuses on understanding the mechanical properties of GFRP materials, the design of bolted and other types of connections, and the impact of these connections on the overall stability and durability of transmission line towers. The unique anisotropic nature of GFRP materials requires specialized design approaches to ensure reliable performance under different loading conditions. The use of Glass Fiber Reinforced Polymer (GFRP) angle members is increasing in structural applications, particularly in environments where corrosion resistance is crucial. However, understanding their connection behavior, especially under tensile loading, is essential for safe and efficient design. GFRP materials exhibit anisotropic behavior, meaning their strength and stiffness vary depending on the direction of the applied load. Pultruded GFRP profiles, commonly used for angle members, have high longitudinal strength but relatively lower transverse strength. The fiber orientation, resin type and manufacturing process influences the material's behavior. Bolted connections are widely used for GFRP angle members, but they can induce stress concentrations and potential failure modes like shear-out and net-tension failure. Adhesive connections offer potential advantages in stress distribution but require careful surface preparation and quality control. Hybrid connections, combining bolts and adhesives, aim to optimize the benefits of both methods. Common failure modes in GFRP angle connections under tensile loading such as Net-tension failure: Fracture of the angle member across the bolt holes. Shear-out failure: Failure of the GFRP material between the bolt-hole and the edge of the member. Bearing failure: Crushing of the GFRP material around the bolt-hole. Factors like edge distance, bolt spacing, and gusset plate dimensions significantly influence the failure mode. Our research focuses on the application of GFRP angle members in transmission line towers (TLT) due to their corrosion resistance and lightweight properties. This study investigates the performance of GFRP angle connections with gusset plates under tensile loads for the different connections. 2. Materials Used and Experimental setup The angle member has dimensions of 50 mm x 50 mm in cross-section and 6 mm thickness for each leg. 3 number of specimens tested per configuration to find failure loads and failure modes. The material is a composite that consists of glass fibers embedded in a polymer matrix, providing both strength and flexibility, which is typical for structural components requiring a balance of lightweight and high-strength properties. Both the GFRP bolts and steel bolts used for the test are of the same size (16 mm diameter and 65 mm length). The bolts are used to secure the GFRP angle member to gusset plates and connect them in a hybrid configuration. GFRP bolts are used to evaluate how a composite material (GFRP) performs in load-bearing applications compared to traditional steel bolts, which serve as a benchmark for the comparison. The epoxy resin and hardener used to bond the GFRP bolts to the GFRP angle member. The resin and hardener form a solid adhesive joint between the materials, ensuring that the hybrid connection remains intact under tensile loading during the test. The gusset plate (6 mm thickness) serves as the fixed connection point for one end of the angle member. The angle member is attached to the gusset plate via the bolts (GFRP or steel) at both ends, forming a lap joint where the angle member and the gusset plate overlap. One end of the GFRP angle member is securely attached to the gusset plate, which is fixed in place. The other end of the GFRP angle member is attached to the testing machine. The machine pulls the angle member in the tensile direction, applying a gradually increasing load. Finally, we finding the failure loads of the angle member for all the cases.