Numerical analysis of pultruded GFRP box girders supporting adhesively-bonded concrete deck in flexure

This paper presents the modeling of pultruded glass fiber reinforced polymer (GFRP) box girders consisting of built-up hat-shape sections and flat plates. The study addresses the effect of a thin concrete deck adhesively bonded to the top GFRP plate on flexural performance, as well as the behavior under positive and negative bending that simulates continuous girders. A three-dimensional finite element (FE) approach is proposed to predict the behavior of the GFRP system, including experimental validation. The efficacy of the girders is compared with other metallic box girders: carbon steel and corrosion-resistant metals, namely, stainless steel and aluminum. Failure is generally due to debonding of the concrete deck, and as such, the ultimate strength is not affected much by the girder material used. The study examines the single girder behavior as well as girder-group systems, to assess load distribution. It is shown that the AASHTO LRFD approach for load distribution can reasonably be used for the proposed girder systems. Design recommendations as to material selection are addressed to better use the girder system.

► GFRP box girders of hat-shape and flat plates adhesively bonded to concrete slab are modeled as continuous and simple spans.
► Study addressed girder-group, load distribution, deformability, code equations, and energy.
► GFRP girder strength was comparable to carbon- and stainless-steel, and aluminum, all failed by debonding of deck.
► GFRP girder showed the lowest stiffness, followed by the aluminum girder, then steel girders.
► The AASHTO LRFD approach for load distribution can reasonably be used for the proposed girder systems.