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

Abstract

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.