Fatigue behavior of adhesively bonded joints composed of pultruded GFRP adherends for civil infrastructure applications

This paper presents results from studies on the fatigue behavior of pultruded GFRP laminates, adhesively bonded double lap joints composed of laminates, and full-scale adhesively bonded FRP bridge deck and steel girder connections. The studies show that the roving fibers are determinant in the tensile fatigue life of the laminates. For the bonded joints, the fatigue resistance depends on the through-thickness interlaminar strength of the GFRP adherends. Adhesively bonded joints are more sensitive to changes in the applied maximum stress than the laminates at an amplitude rate of 0.1, however, the degradation rate of strength is almost the same for both. The applied maximum fatigue load affects the stiffness degradation rate of GFRP laminates; the bonded joints do not experience significant stiffness degradation when applied to fatigue loading. Adhesively bonded FRP bridge deck-to-steel girder connections showed no sensitivity to fatigue loading in the longitudinal bridge direction. However, the sensitivity to uplift fatigue loading in the transversal bridge direction was not negligible.