The Mechanical Behaviour and Failure Mode of FRP Composite Steel Casing Joints

Fibre reinforced plastic (FRP) composite has been widely used in engineering due to its light weight, high strength, and corrosion resistance. Joint behaviour is important in structural design. This research investigated the ultimate tensile and compressive bearing capacities of bonding joints of Φ200 mm x 10 mm steel casing. By conducting full-scale tests, the load-displacement curve and strain distribution in joints in an FRP composite steel casing were analysed, and the ultimate bearing capacity, stiffness, and failure mode were obtained. The research showed that under axial compression, joints underwent brittle failure, and the steel casing exerted a greater lateral restraint to the composite pipe, which resulted in a decrease of bearing capacity of its components. While under axial tension, the failure mode of joints was such that the FRP composite pipe was pulled off and the bearing capacity of its joints was determined by the strength of the binders used. This study forms an experimental basis for engineering application.