Energy dissipation and recovery in web–flange junctions of pultruded GFRP decks

The energy dissipation capacity resulting from progressive cracking and the recovery after unloading of the web–flange junctions (WFJs) of a pultruded GFRP deck were experimentally investigated. Web–cantilever bending experiments up to failure were performed on two WFJ types (If-o, Ic-o) with similar geometry and fiber architecture but different initial imperfections (deviations from the fiber architecture design, wrinkling of fabrics, resin pockets, pre-cracks). Dissimilar imperfections changed the WFJ behavior from brittle (If-o) to ductile (Ic-o): different crack sequences were observed, which resulted in an abrupt failure in If-o WFJs and a progressive failure in Ic-o WFJs, in addition to a higher load-bearing capacity of the latter. The Ic-o WFJs exhibited significant recovery; a small influence of the FRP viscoelastic properties on recovery and a constant damage rate were observed. The total and dissipated energies of the Ic-o WFJs and their ductility index, defined as the ratio of the dissipated to total energy, were modeled. The main energy dissipation mechanism of the Ic-o WFJs was related to crack development; dissipation through viscoelastic losses was significant only at low deflection levels.