Rotational stiffness of web-flange junctions of pultruded GFRP decks

The rotational behavior of the web-flange junctions (WFJs) of a pultruded glass fiber-reinforced polymer (GFRP) bridge deck system with trapezoidal cell cross-sectional geometry was investigated. The rotational response of three WFJ types, in two bending moment directions each, was characterized. An experimental procedure based on three-point bending and cantilever experiments conducted on the web elements and simple analytical models was used. The WFJs generally exhibited non-rigid and nonlinear behavior. The overall moment-rotation relationships, rotational stiffness, strength and failure modes differed depending on the web type, the location of the WFJ within the deck profile, the existing initial imperfections and the direction of the bending moment applied. This evidenced the relevance of separately characterizing the response of all WFJ types in the two possible bending directions. Simplified expressions to model the WFJ rotational behavior were derived. The validity of the experimental and idealized rotational responses was assessed by means of numerical simulations of full-scale experiments conducted on the GFRP deck.