Tensile Behavior of Pultruded Fiber-Reinforced Polymer Laminates with Bonded and Bolted Splice Joints

Abstract

This paper presents an experimental investigation on double-lap joints of grit-blasted surface finish fiber-reinforced polymer (FRP) splice plates bonded and bolted to FRP laminates. Eighteen coupon joint specimens were tested under tensile loading with varying types of FRP splice plates and FRP laminates. Four types of bolts were evaluated: FRP bolts, high corrosion-resistant steel (HCRS) bolts, stainless steel (SS) bolts, and SS bolts wrapped with glass FRP (GFRP) (referred to as “SF” bolts). The test results indicated that double-lap splice joints, which incorporated HCRS bolts, epoxy adhesive, and grit-blasted surface finish FRP splice plates, provided strong bonds with FRP laminates. The grit-blasted surface finish of the FRP splice plates and the epoxy adhesive contributed to improving joint stiffness and strength. The specimens with FRP bolts showed brittle behavior and failed at relatively low ultimate load. The failures of those specimens were debonding of epoxy layers followed by shearing of the FRP bolts. The specimens with steel bolts (i.e., HCRS, SS, and SF bolts), however, exhibited ductile behavior and failed at a much higher ultimate load than did the FRP bolt specimens. Typical failure modes of the steel bolt specimens were fracturing of the FRP laminate (resulting from fiber rupture or kink, shear-out, and delamination failure of the GFRP plies and bearing failure of FRP materials near the edge of bolt holes in the load direction), bearing failure of the FRP splice plates, epoxy debonding, and yielding of bolts. Although FRP wraps may enhance the durability of the SS bolts, the use of SF bolts may significantly affect the failure mode of the splice joints.