Fibre waviness in pultruded bridge deck profiles: Geometric characterisation and consequences on ultimate behaviour

Abstract

Conventional tests cannot be used to establish the important influence of fibre waviness, a manufacturing legacy at the flange-web joints (FWJs) of pultruded GFRP bridge decks, on the local ultimate behaviour of such decks. Hence a novel, simple and reliable three-step experimental scheme for that purpose is presented herein, using one pultruded deck profile as an exemplar. First, for the given profile, the different individual and bonded deck-deck joint geometries which must be targeted for testing are identified. Second, an effective manual method is put forward to map this waviness at the FWJs. Third, a quasi-static test setup is introduced which enables statically determinate loading of one joint at a time, while also ensuring continuity between this joint and the remaining deck so that the real load paths within the deck are preserved. During the tests failure always occurred by fracture of the wavy fibre-resin interfaces within the FWJs, with a distinct inverse correlation between fibre waviness and failure load, and with the influence of bonding on joint failure behaviour depending on the local flange-web layout. It is concluded that this simple test is sufficiently reliable for extension to assessing local fatigue behaviour at the joints.

Mechanisms of Origin and Classification of Out-of-Plane Fiber Waviness in Composite Materials—A Review

“…Coogler et al [152] examined the various process-induced imperfections that can occur in the cross sectional areas of pultruded GFRP profiles for bridge decks. In general, fiber waviness can be particularly pronounced within the flange-web joints/junctions in pultruded profiles [152][153][154][155][156][157][158], to the extent that the fibers often return upon themselves, essentially describing U-trajectories, as a web lamina transitions from the vertical to horizontal direction. Sebastian [153] characterized fiber waviness in pultruded profiles and experimentally investigated the ultimate mechanical behavior.…”

“…themselves, essentially describing U-trajectories, as a web lamina transitions from the vertical to horizontal direction. Sebastian [153] characterized fiber waviness in pultruded profiles and experimentally investigated the ultimate mechanical behavior. Elhajjar [79] stated that random inplane waviness can occur in pultrusion due to temporarily/locally insufficient tow tension (e.g., from one of the feeding spools).…”

Mesoscale Process Modeling of a Thick Pultruded Composite with Variability in Fiber Volume Fraction

“…Detailed analyses of fiber misalignment, fiber mat misalignment, resin-rich areas, and void topology in pultrusion products have been performed via optical micrography, Fourier transformation, and computational tomography [34][35][36]. In addition to the characterization of the variability in fiber distribution, its effects on a pultruded bridge deck profile's ultimate properties/performance were investigated in [37]. The effect of non-uniform fiber distribution on the cure degree and temperature evolution through the process was studied numerically in [38].…”

Taxonomy of fibre mat misalignments in pultruded GFRP bridge decks

“…As shown in Figure 1(a), the fibre mats in a GFRP deck are often randomly misaligned in the transverse (normal-to pultrusion) direction. The term "fibre waviness" is commonly used to describe this type of defect [2]. However, for pultruded decks the trajectory of the mats can take various forms.…”

“…In a recent study by Sa et al [9], Figure 3 of their paper clearly shows misalignment of the mats passing through the WFJ for a 'snap-fit' pultruded GFRP deck manufactured in Korea. Sebastian et al [2] presented a first attempt at measuring the fibre mat "waviness" in a unit of Fiberline ASSET deck, by manually plotting points along each fibre mat layer on a transparent plastic sheet using a sharp-pointed marker.…”