Experimental behavior of monolithic composite cuff connections for fiber reinforced plastic box sections

A series of laboratory experiments investigated the structural performance of monolithic composite cuff connections for attaching pultruded fiber reinforced plastic (FRP) box sections. Cuff connections of three thicknesses were produced using the VARTM process, with fiber orientation selected to favor the mechanical response for this application. Test frames were assembled with the cuffs connecting box beams and columns (of pultruded FRP or steel), using adhesive bonding. Twelve frames were tested, each subjected to either cyclic or monotonic loading until failure; frame behavior was evaluated from the standpoints of stiffness and strength. Monolithic cuff connections of moderate thickness were capable of developing the flexural capacity of a pultruded FRP box beam (with proper detailing), and the cuffs themselves exhibited somewhat ductile failure modes upon reaching their maximum load. Cuff connection flexibility was a relatively minor contributor to overall frame displacement. The pultruded FRP frames were stronger and stiffer than previous generation approximations of an ideal cuff connection for similar box beam and column members.