GFRP Deck Research Articles

Taxonomy of fibre mat misalignments in pultruded GFRP bridge decks

This paper presents a taxonomy of the fibre mat misalignments found in a multi-celled pultruded GFRP deck, based on high-resolution images of the polished cross sections. A dual approach to misalignment taxonomy is presented, one based on misalignment morphology, the other grounded in the manufacturing provenance of the misalignments. Each misalignment is characterised using, alternately, a Gaussian function, the angle to its steepest tangent, its length and its height. Some scatter in the type and severity of the misalignments was found within the web-flange junctions. The deck’s top flange was found to be thicker in regions containing a double-backed or flipped mat layer, which was probably due to displacement of the internal mandrels during pultrusion. Analysis shows that as wrinkle amplitude increases, there is a switch from mat failure at constant load to interlaminar failure at rapidly decreasing load. Finally, recommendations are made for minimising fibre misalignments due to manufacturing.

Transverse bending and in-plane shear behaviours of multicellular pultruded GFRP deck panels with snap-fit connections

This paper presents experimental and numerical investigations about the transverse bending and in-plane shear behaviours of pultruded bridge deck panels made of E-glass fiber reinforced polymer (GFRP). The analysed panels have a wide multicellular thin-walled cross-section, with panel-to-panel vertical interlocks (snap-fit) at the lateral edges. The study aimed at understanding and quantifying the structural contribution of the deck panels, in terms of their transverse stiffness and strength properties, w. r.t the load transmission to the lower support girder system along its longitudinal axis (bridge's main axis). Particular focus was given to the influence of the panel-to-panel joining system on the transverse performance of the deck when compared to a continuous panel (i.e. without snap-fit). The effects of complementing the snap-fit connection with two different structural adhesives was also investigated. For all deck configurations tested, the structural response in bending and shear exhibited high post-cracking strength and pseudo-ductility (above 100% and 200% respectively), as a consequence of the redundancy provided by the multi-cellular section. Compared to a continuous deck, the mechanical snap-fit exhibited very high deformability; however, when combined with adhesive bonding, it behaved fairly rigidly. In general, failure occurred in a progressive way (crack initiation and propagation) and the ultimate capacity was governed by the web-flange junctions. The numerical simulations, which were performed with continuum shell finite element (FE) models using Hashin-based damage analysis, provided useful insights about the failure mechanisms. Both bending and in-plane shear responses were simulated with good accuracy, with matrix tension failure governing the load capacity. The low value of the estimated in-plane shear modulus was consistent with the very low interaction degree (3–4%) that was assessed between the panels' flanges under bending, thus highlighting the high flexibility of this bridge deck's multicellular core when subjected to transverse loading.

Commentary: Restoring the West Mill GFRP Deck Road Bridge to full capacity

Commentary: Restoring the West Mill GFRP Deck Road Bridge to full capacity

Ultimate limit design of composite beams with modular GFRP deck and steel girder

This paper analytically formulates the ultimate capacities for various failure modes of composite beams consisting of a modular fiber reinforced polymer (FRP) web-flange sandwich deck supported by a steel girder. Pultruded FRP box sections are incorporated between two flat panels to form the web-flange sandwich deck, in which the pultrusion direction of box sections can be either parallel or perpendicular to the span direction. Such a deck can then be assembled via adhesive bonding or blind bolt connections to a supporting steel girder to form a composite beam system. On the basis of theoretical analysis of critical sections for such composite beams at ultimate states, potential failure modes are identified, including flexural failure of the steel girder yielding in tension and GFRP deck failure in compression, vertical shear failure, and horizontal shear failure at adhesive bonding at bolted connections and at webs of FRP box sections. For each failure mode, the corresponding ultimate capacity is analytically formulated; thereby, the critical failure mode and ultimate load capacity can be determined. The developed ultimate limit design approaches are validated by experimental results from the literature for such FRP-steel composite beams.

Flexural performance of a hybrid GFRP-concrete bridge deck with composite T-shaped perforated rib connectors

In this study, the flexural performance of an innovative hybrid GFRP-concrete deck is evaluated. The proposed hybrid composite deck consists of a pultruded GFRP plate with T-shaped perforated ribs for resisting tensile stresses, while concrete with reinforcements is placed at the compressive side of the deck. In order to better understand the flexural performance of proposed hybrid decks under sagging moment, a total of six full-scale hybrid deck models were experimentally investigated. Five test parameters were considered, namely: (i) hole spacing, (ii) presence of bent-up rebars, (iii) quality of GFRP composites surface treatment, (iv) deck depth, and (v) type of reinforcements. Experimental results identified three different typical failure modes, namely: diagonal and longitudinal shear, as well as flexure. Furthermore, it was found that the inclusion of bent-up rebars, sand bonded to GFRP plates surfaces, and increasing deck thickness enhance the ultimate strength of the proposed hybrid deck. It was also concluded that the hole spacing and the reinforcement type have negligible influence on ultimate capacity of the proposed deck. Moreover, finite element models considering the laminate damage based on Hashin’s theory were built and load transfer and failure mechanisms of GFRP perforated ribs were discussed. The validity of the proposed analytical method, with respect to failure mode and ultimate strength for the hybrid deck, was confirmed through the close correlation between analytical and experimental results.

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.

System transverse in-plane shear stiffness of pultruded GFRP bridge decks

The static transverse behavior of two pultruded GFRP deck systems with trapezoidal (DS) and triangular (AS) cell cross-sectional geometry was experimentally investigated in order to study their transverse in-plane shear stiffness. Symmetric three-point bending experiments up to failure were performed on 200-mm-wide beams. Their stiffness, strength and failure modes were compared. Different load transfer mechanisms were found in the DS (frame-dominated) and AS (truss-governed) systems depending on the cell geometry. The DS beams exhibited a lower apparent bending stiffness (24–30 times less) and degree of composite action between the flanges (14–17 times less) than the AS beams. These dissimilarities were attributed to the lower transverse in-plane shear stiffness provided by the trapezoidal core than by the triangular core. The low bound values for both system in-plane shear moduli were estimated from the experimental deflection results. The system in-plane shear modulus of the DS beams represented approximately 2–3% of that of the AS beams.

Delamination of GFRP Panels in Bridge Decks

Modern bridge structures need light decks with long durability and promising technical parameters. GFRP bridge deck creates possibilities in bridge designing. Parallel identification of GFRP deck panel: DTA analysis, spectroscopy analysis, scanning and optical microscope monitoring according to own investigation will be presented, in the paper. Modal, vibrations analysis is very important for bridge structures using light Glass Fiber Reinforced Polymer decks. The three 1stmodes and corresponding frequencies have been showed for chosen footbridges with GFRP ASSET system decks. The footbridges were excited by impact and human-induced vibrations. Good exploration of new material, like composite GFRP, generates potential to improve technology and make comparison analysis with traditional standard of materials. The dynamic behavior of damaged footbridge structures under moving loads has been studied. The paper is concerned with a micromechanical theory of macroscopic crack propagation due to stress-corrosion cracking in unidirectional glass-fiber-reinforced polymer composites, for bridge decks applications. The first form of damage in laminates is usually matrix micro cracks, which are intralaminar or ply cracks that traverse the thickness of the ply and run parallel to the fibers in that ply. The identification of early delamination process in footbridges GFRP deck is very important by them durability feature. Improving system for polymer resin using nanostructures is useful by aspect of reducing micro cracks and then macro cracks propagation.

Bridge Structures with GFRP Composite Deck

In this paper, author’s first part of research of GFRP bridge deck (using ASSET fiber line composite modular system) took part at AGH University of Science and Technology Laboratory of Glass Technology and Amorphous Coatings Department. The analysis consisted spectrometer analysis of chemical constitution of glass fiber, identification of material according to Fourier spectroscopy, electronic scan microscopy (SEM/EDAX) and DTA analysis. The modal FEM analysis of chosen footbridge with light GFRP deck has been presented in the paper.

Behavior of an adhesive joint under weak-axis bending in a pultruded GFRP bridge deck

It has been more than twenty years since the application of GFRP bridge decks in construction fields. Recently, a few studies by governments and individual researchers have investigated in-use GFRP bridge decks. Areas of trouble include the problems of cracking, spalling and the de-bonding of the pavement or the wearing surface on GFRP bridge decks, all of which affect the long-term durability and serviceability of these new construction materials. Related to these problems, reflective cracks on asphalt pavement are directly related to pultruded GFRP bridge decks.In this paper, the behavior of an adhesive joint under weak-axis bending was investigated to identify the causes of pavement cracks in in-use pultruded GFRP bridge decks. In detail, this paper initially describes a designed section of a pultruded GFRP deck tube while accounting for the effects of the section geometry through bending tests and for the connections to the girders. The study also describes connection methods of creating adhesively bonded joints between GFRP tubes and panels and presents possible sources of pavement cracks on the GFRP decks. The flexural stiffness and the load-carrying capacities in strong and weak axes are measured during bending tests on pultruded GFRP decks. Next, tensile local failures of an epoxy adhesive due to the concentration of deformations at adhesive joints are identified via a weak-axis bending test. Finally, the tensile failure of an epoxy adhesive due to the local concentration of deformation at an adhesive joint under weak-axis bending is verified through a finite element analysis.The bending tests and FE analyses of a pultruded GFRP bridge deck under weak-axis bending show that local deformations are prone to concentrate at the adhesive joints which form a flexible and weak region due to the relatively low elastic modulus and strength of the epoxy adhesive. Strong-axis bending has a dominant influence on the global behavior of a deck subjected to bi-directional bending. On the other hand, weak-axis bending, which affects the behavior of adhesive joints, also has a strong influence on pavement cracks. Reflective cracks on the pavement of pultruded GFRP bridge decks can occur due to the local concentration of deformations at adhesive joints on the surfaces of GFRP decks under weak-axis bending, even before the tensile failure of the epoxy at the edges of the adhesive joints due to the higher elastic modulus and the lower tensile strength of the asphalt pavement compared to these properties of the epoxy. To prevent reflective cracks on the pavement of pultruded GFRP bridge decks, design improvements or reinforcing measures for deck connection structures which distribute and minimize the concentrated local deformation on adhesive joints are required.

Composite GFRP Deck for Bridge Structures

Composite material of glass fiber base is very promising material for future structures. It is possible to create bridge span consists of steel main beams and GFRP deck, according for example ASSET system. The author's research is about parameters of composite material of bridge deck like alternative for concrete one. Identification of kind of glass fiber and type of polymer matrix or type of adhesive with steel or concrete, there are very interesting directions of searching line. The paper will be presented the results of DTA and spectroscopy analysis of GFRP composite, according own paper author's research. It will be described the examples of bridges where GFRP deck have been constructed with main steel beams. The text will give horizon of future author's research of this kind of bridges. Future model stress and fatigue analysis will be showed by main topics. Presented kind of bridges are good alternative for traditional structures by long durability, anticorrosion, light deck with imposing stress parameters.

Experimental investigation of movable hybrid GFRP and concrete bridge deck

This paper proposed a novel cost-effective movable hybrid GFRP and concrete deck consisting of corrugated pultruded GFRP plate with T-upstands for the tension part and concrete with reinforcing bars for the compression part. First, the strength and stiffness of GFRP plate serving as formworks for concrete casting under construction stage was verified by sand filling test. Then, static tests on six full-scale models with different penetrating bars and surface treatment under sagging moments were conducted to evaluate the load-carrying capacity and failure modes of proposed hybrid deck. The load and displacement relationship, ultimate flexural resistance, strain distribution on GFRP plate and concrete slab were measured during the test. Experimental results indicated that both surface treatment and penetrating bars improve the connection between GFRP plate and concrete, and promote the ultimate strength and rigidity of hybrid deck. In addition, the concrete used for encasing corrugated pultruded GFRP plates not only increases its stiffness, but also prevents local buckling failure of the GFRP plate with T-upstands. The comparison of experimental and theoretical ultimate strength results showed ACI 440 flexure and shear equation can effectively predict the ultimate capacity for the hybrid deck. The overall investigation showed the presented hybrid GFRP and concrete concept is a better alternative for beam-and-slab bridges.

Analytical verification of a composite level of bolted GFRP bridge deck-to-girder connection system

There are various ways to connect a GFRP deck and girder which have been adopted as systems worldwide such as connection systems that use shear connectors and mechanical connection systems that use bolts or clamps, and recently there has been a study on a system to connect GFRP deck and steel girder using a bonding agent. In this study, an attempt was made to review and analyze the composite level of GFRP decking and a girder bolt connection system using the already proposed GFRP deck shape. In addition, an attempt was made to estimate the decreased rate of the composite level at various bolt connection intervals using the calculated strain and deflection, and also the analytical values of the composite level were compared with prior test results.

The static behavior of a modular foam-filled GFRP bridge deck with a strong web-flange joint

The static behavior of a modular bridge deck filled with a low-density polyurethane foam was experimentally investigated. The web-flange joint of the deck was strong enough so that a failure of the deck in the transverse direction was governed by the delamination of the bond between two adjacent modules whether the deck was filled or not. Although the elastic modulus of the foam was only a thousandth of the homogenized modulus of the GFRP deck, the structural performance of the deck in the transverse direction was significantly improved by the foam filled inside the deck. It was shown experimentally that tensile stress could develop in the top flange of the deck subjected to three point bending because of shear deformation. Such a development of tensile stress was significantly mitigated by the foam filled inside the deck.

Experimental study on durability comparison of the GFRP decks by resin types

As a structural member that is exposed to the environment, bridge decks are affected by the surrounding conditions including temperature and humidity. Especially, temperature shock caused by burning vehicles on the deck, chemical reactions by dissimilar materials or salinity on the bridges near the seaside can cause serious damage to bridge decks and therefore, they have to be resistant to such environmental factors. In this study, in order to evaluate the endurance properties of GFRP decks according to the type of applied resin, a variety of durability evaluation tests were conducted including the basic physical properties tests with polyester applied GFRP decks. The results of the tests were compared with the tests with vinylester applied GFRP deck to analyze the difference in the durability by resin type.

Performance verification of a new pultruded GFRP bridge deck-to-girder connection system

There are various ways to connect the GFRP deck and girder which have been adopted as systems worldwide: including the use of a shear connector, and mechanical connection systems that utilize bolts or clamps. Recently, there have been studies on the systems to connect the GFRP deck and steel girder using a bonding agent. This paper proposes a new connection system, which is different from the GFRP deck-to-girder connection system that has been applied so far. In addition to evaluate the structural performance of the proposed connection system, it is compared with the bolted mechanical connection system via testing and FEM analysis under the same conditions.

Testing, Analysis, and Evaluation of a GFRP Deck on Steel Girders

North Carolina has recently installed a fiber-reinforced polymer (FRP) deck on steel girders at a site in Union County. The bridge was instrumented with foil strain gauges, strain transducers, and displacement transducers. The bridge was then tested with a simulated MS-22.5 design load. Experimental data confirmed full composite interaction between the girders and the FRP deck panels. The neutral axis was measured to be 383 mm above the bottom flange of the 618-mm-deep girder. It was found that composite action could be estimated within 3% using a transformed section analysis of the deck panels. For two lanes loaded, the maximum live load distribution factor was computed to be 0.75. When looking at the overall performance of the structure, the deck deflected 5 mm, with the allowable stress at least 10 times over the maximum stress measured in the material. The girder deflection of 7 mm was well within the parameters set forth by AASHTO. Simple span deflection equations were found to conservatively model the anticipated deflection of the girders when using the transformed section properties.

Experimental characterization of a pultruded GFRP bridge deck for light-weight vehicles

A composite bridge deck system assembled from a modular profile with double-rectangular cells has been developed for light-weight vehicles. This paper presents the experimental characterization of the flexural performance of pultruded GFRP decks under static loading. Several tests were carried on single module and adhesively bonded modules. The specimen details such as dimensions, material properties and fiber architecture are given. Numerical verification is performed by using the general purpose finite element package ABAQUS. Experimental set-up, instrumentation, testing procedure, failure modes and the results of these experiments have been discussed in detail.

Degree of composite action verification of bolted GFRP bridge deck-to-girder connection system

There are modes to connect GFRP deck and girder, which have been adopted as systems worldwide: connection system using shear connector; mechanical connection systems using bolt or clamp; and also there has been a study on a system to connect GFRP deck and steel girder using bonding agent recently. In this paper, the degree of composite action for the bolt connection system, one of the mechanical connection systems of such connection systems, is experimentally verified by static test. And also the relevancy between neutral axis changes and bolt connection system is analyzed by comparing the theoretical neutral axis with the neutral axis extracted from the test result for the degree of composite action calculation.

Pilot test on a developed GFRP bridge deck

In this paper, an optimum design technique is developed which can be applied to bridge decks based on FRP materials with more complex objective functions and constraints than those of existing materials. The proposed optimum design technique is applied to determine optimum geometry for bridge decks and properties of the FRP material by carrying out three-dimensional numerical modeling. In addition, FRP deck modules have been produced using the pultrusion method after considering the proposed optimum cross-section shape and property of the material, and several tests have been performed to validate the performance of the developed GFRP deck.