FEA of Complex Bridge System with FRP Composite Deck

Innovative fiber-reinforced polymer (FRP) composite highway bridge deck systems are gradually gaining acceptance in replacing damaged/deteriorated concrete and timber decks. FRP bridge decks can be designed to meet the American Association of State Highway and Transportation Officials (AASHTO) HS-25 load requirements. Because a rather complex sub- and superstructure system is used to support the FRP deck, it is important to include the entire system in analyzing the deck behavior and performance. In this paper, we will present a finite-element analysis (FEA) that is able to consider the structural complexity of the entire bridge system and the material complexity of an FRP sandwich deck. The FEA is constructed using a two-step analysis approach. The first step is to analyze the global behavior of the entire bridge under the AASHTO HS-25 loading. The next step is to analyze the local behavior of the FRP deck with appropriate load and boundary conditions determined from the first step. For the latter, a layered FEA module is proposed to compute the internal stresses and deformations of the FRP sandwich deck. This approach produces predictions that are in good agreement with experimental measurements.     

Fatigue and Strength Evaluation of Two Glass Fiber-Reinforced Polymer Bridge Decks

The use of glass fiber-reinforced polymer (GFRP) bridge decks is appealing for applications where minimizing dead load is critical. This paper describes fatigue and strength testing of two types of GFRP decks being considered for use in the retrofit of an aging steel arch bridge in Snohomish County, Washington, where a roadway expansion is necessary and it is desirable to minimize the improvements to the arch superstructure. Each test used a setup designed to be as close as practicable to what will be the in situ conditions for the deck, which included a 2% cross slope for drainage. The fatigue testing consisted of a single 116 kN (26 kip) load applied for 2 million cycles, which corresponds to an AASHTO HS-25 truck with a 30% impact factor, and the strength testing consisted of multiple runs of a monotonically applied minimum load of 347 kN (78 kips). Results from the fatigue testing indicated a degradation of the stiffness of both deck types; however, the degradation was limited to less than 12% over the duration of loading. Further, the results showed both deck types accumulated permanent deck displacement during fatigue loading and one deck type used a detail with poor fatigue performance. That detail detrimentally impacted the overall deck performance and caused large permanent deck deformations. It was also found that degradation of composite behavior between the deck and girders occurs during fatigue loading and should be included in design.     

Conformable Tire Patch Loading for FRP Composite Bridge Deck

Fiber-reinforced polymer (FRP) composites are increasingly being used in bridge deck applications. However, there are currently only fledgling standards to design and characterize FRP deck systems. One area that should be addressed is the loading method for the FRP deck. It has been observed that the type of loading patch greatly influences the failure mode of a cellular FRP deck. The contact pressure distribution of a real truck loading is nonuniform with more concentration near the center of the contact area as a result of the conformable contact mechanics. Conversely, the conventional rectangular steel patch on a FRP deck act like a rigid flat punch and produces stress concentration near the edges. A proposed simulated tire patch has been examined for loading a cellular FRP deck with the load distribution characterized by a pressure sensitive film sensor and three-dimensional contact analysis using ANSYS. A loading profile is proposed as a design tool for analyzing FRP deck systems for strength and durability. Local top surface strains and displacements of the cellular FRP deck are found to be higher with proposed loading profile compared to those for the conventional uniformly distributed loading. Parametric studies on the deck geometry show that the global displacement criterion used for characterizing bridge deck is inadequate for a cellular FRP deck and that the local effects must be considered.     

Structural Behavior of FRP Composite Bridge Deck Panels

Fiber-reinforced polymer (FRP) composite bridge deck panels are high-strength, corrosion resistant, weather resistant, etc., making them attractive for use in new construction or retrofit of existing bridges. This study evaluated the force-deformation responses of FRP composite bridge deck panels under AASHTO MS 22.5 (HS25) truck wheel load and up to failure. Tests were conducted on 16 FRP composite deck panels and four reinforced concrete conventional deck panels. The test results of FRP composite deck panels were compared with the flexural, shear, and deflection performance criteria per Ohio Department of Transportation specifications, and with the test results of reinforced concrete deck panels. The flexural and shear rigidities of FRP composite deck panels were calculated. The response of all panels under service load, factored load, cyclic loading, and the mode of failure were reported. The tested bridge deck panels satisfied the performance criteria. The safety factor against failure varies from 3 to 8.     

Failure Study of an Aluminum Bridge Deck Panel

Aluminum bridge decks may prove to be an alternative to concrete decks for improving the performance of structural bridge systems. Combining excellent corrosion resistance with extremely low density, aluminum decks can prolong surface life, facilitate the construction process, and expand rehabilitation capabilities. Reynolds Metals Company, Richmond, Va., has invested considerable resources to develop a proprietary aluminum deck system. The Virginia Department of Transportation agreed to employ the Reynolds deck system in two projects. Using Federal Highway Administration sponsorship, the Virginia Transportation Research Council initiated a study to evaluate the aluminum deck system. The first phase of this project analyzed the static response of a 2.74 × 3.66 m (9 × 12 ft) deck panel. Both service-load tests and ultimate-load tests were performed on the panel at the Turner-Fairbank Structural Laboratory. The experimental and analytical evaluation of the ultimate load static tests is the subject of this paper. The failure load and failure mechanism were predicted with great accuracy. The model data predicted panel failure at a load of 911.89 kN (205 kips) by yielding under the load patch while failure during the laboratory test occurred at a load of 872.07 kN (196.05 kips) by gross yielding underneath the load patch.     

Laboratory and Field Performance of Cellular Fiber-Reinforced Polymer Composite Bridge Deck Systems

This paper addresses the laboratory and field performance of multicellular fiber-reinforced polymer (FRP) composite bridge deck systems produced from adhesively bonded pultrusions. Two methods of deck contact loading were examined: a steel patch dimensioned according to the AASHTO Bridge Design Specifications, and a simulated tire patch constructed from an actual truck tire reinforced with silicon rubber. Under these conditions, deck stiffness, strength, and failure characteristics of the cellular FRP decks were examined. The simulated tire loading was shown to develop greater global deflections given the same static load. The failure mode is localized and dominated by transverse bending failure of the composites under the simulated tire loading as opposed to punching shear for the AASHTO recommended patch load. A field testing facility was designed and constructed in which FRP decks were installed, tested, and monitored to study the decks’ in-service field performance. No significant loss of deck capacity was observed after more than one year of field service. However, it was shown that unsupported edges (or free edges) are undesirable due to transitional stiffness from approach to the unsupported deck edge.     

Sustained-Load and Fatigue Performance of a Hybrid FRP-Concrete Bridge Deck System

The design and construction of bridge systems with long-term durability and low maintenance requirements is a significant challenge for bridge engineers. One possible solution to this challenge could be through the use of new materials, e.g., fiber-reinforced polymer (FRP) composites, with traditional materials that are arranged as an innovative hybrid structural system where the FRP serves as a load-carrying constituent and a protective cover for the concrete. This paper presents the results of an experimental investigation designed to evaluate the performance of a 3/4 scale hybrid FRP-concrete (HFRPC) bridge deck and composite connection under sustained and repeated (fatigue) loading. In addition, following the sustained-load and fatigue portions of the experimental study, destructive testing was performed to determine the first strength-based limit state of the hybrid deck. Results from the sustained-load and fatigue testing suggest that the HFRPC deck system might be a viable alternative to traditional cast-in-place reinforced concrete decks showing no global creep behavior and no degradation in stiffness or composite action between the deck and steel girders after 2 million cycles of dynamic loading with a peak load of 1.26 times the scaled tandem load (TL). Furthermore, the ultimate strength test showed that the deck failed prior to the global superstructure at a load approximately six times the scaled TL.     

Service and Ultimate Load Behavior of Bridge Deck Reinforced with Carbon FRP Grid

A full-scale model of a bridge deck slab isotropically reinforced with 0.3% fiber-reinforced plastic reinforcement (FRP) was tested. The 6 m long slab of 185 mm thickness had two 2 m spans and 1 m cantilevers on both sides. The slab was first loaded monotonically to crack the concrete. Then it was loaded cyclically in three stages of 4 million cycles each at a frequency of 5 Hz, with the load varying between 0 and 100 kN in the first two stages and between 0 and 125 kN in the last. Finally, it was loaded monotonically to failure. Constructability of the slab with the FRP reinforcement was found satisfactory. The cyclic load test shows that deflections and stresses are small, and the degradation indicated by increases in deflections and stresses after 4 million cycles of overloading by 25% is very small. The ultimate load capacity of the slab was at least five times the maximum wheel load of 100 kN, and the failure mode was punching shear. Long-term performance of FRP reinforcement under the combined effect of exposure to the chemical environment and loading needs to be studied to evaluate durability, and hence cost-effectiveness, of FRP reinforcement in bridge decks.     

Fatigue Life Evaluation of Concrete Bridge Deck Slabs Reinforced with Glass FRP Composite Bars

Since bridge deck slabs directly sustain repeated moving wheel loads, they are one of the most bridge elements susceptible to fatigue failure. Recently, glass fiber-reinforced polymer (FRP) composites have been widely used as internal reinforcement for concrete bridge deck slabs as they are less expensive compared to the other kinds of FRPs (carbon and aramid). However, there is still a lack of information on the performance of FRP–reinforced concrete elements subjected to cyclic fatigue loading. This research is designed to investigate the fatigue behavior and fatigue life of concrete bridge deck slabs reinforced with glass FRP bars. A total of five full-scale deck slabs were constructed and tested under concentrated cyclic loading until failure. Different reinforcement types (steel and glass FRP), ratios, and configurations were used. Different schemes of cyclic loading (accelerated variable amplitude fatigue loading) were applied. Results are presented in terms of deflections, strains in concrete and FRP bars, and crack widths at different levels of cyclic loading. The results showed the superior fatigue performance and longer fatigue life of concrete bridge deck slabs reinforced with glass FRP composite bars.     

Field Performance of the Fiber-Reinforced Polymer Deck of a Truss Bridge

The MD 24 Bridge over Deer Creek in Harford County, Md., was one of the projects chosen by the Federal Highway Administration’s Innovative Bridge Research and Construction Program for bridge deck replacement by fiber-reinforced polymer (FRP) composites. A thorough discussion is presented on Maryland State Highway Administration’s first bridge rehabilitation project utilizing a FRP deck. The discussion includes design details, installation procedure, construction methods and in situ load testing with a wireless monitoring system. The research team installed a monitoring system to record the effects of live loads on the bridge system, including truss members, steel stringers, and plate action of the FRP deck. Finite-element models were also used in this phase. Dynamic effects of the FRP system, composite action between steel stringers and the FRP deck as well as the effective width and distribution factors of stringers were obtained and compared with the AASHTO specifications. Recommendations are also offered on improving the design details based on this experience.     

Development and Evaluation of an Adhesively Bonded Panel-to-Panel Joint for a FRP Bridge Deck System

A fiber-reinforced polymer (FRP) composite cellular deck system was used to rehabilitate a historical cast iron thru-truss structure (Hawthorne St. Bridge in Covington, Va.). The most important characteristic of this application is reduction in self-weight, which raises the live load-carrying capacity of the bridge by replacing the existing concrete deck with a FRP deck. This bridge is designed to HL-93 load and has a 22.86?m clear span with a roadway width of 6.71?m. The panel-to-panel connections were accomplished using full width, adhesively (structural urethane adhesive) bonded tongue and groove splices with scarfed edges. To ensure proper construction, serviceability, and strength of the splice, a full-scale two-bay section of the bridge with three adhesively bonded panel-to-panel connections was constructed and tested in the Structures Laboratory at Virginia Tech. Test results showed that no crack initiated in the joints under service load and no significant change in stiffness or strength of the joint occurred after 3,000,000 cycles of fatigue loading. The proposed adhesive bonding technique was installed in the bridge in August 2006.     

Evaluation of Composite Sandwich Bridge Decks with Hybrid FRP-Steel Core

A hybrid concept of composite sandwich panel with hybrid fiber-reinforced polymer (FRP)—steel core was proposed for bridge decks in order to not only improve stiffness and buckling response but also be cost efficient compared to all glass fiber-reinforced polymer (GFRP) decks. The composite sandwich bridge deck system is comprised of wrapped hybrid core of GFRP grid and multiple steel box cells with upper and lower GFRP facings. Its structural performance under static loading was evaluated and compared with the ANSYS finite element predictions. It was found that the presented composite sandwich panel with hybrid FRP-steel core was very efficient for use in bridges. The thickness of the hybrid deck may be decreased by 19% when compared with the all GFRP deck. The failure mode of the proposed hybrid deck was more favorable because of the yielding of the steel tube when compared with that of all GFRP decks.     

Temporal Thermal Behavior and Damage Simulations of FRP Deck

The finite-element method (FEM) has been employed to study the structural behavior of the fiber-reinforced polymer (FRP) bridge deck. The numerical results were verified with the field-test results provided by New York State Department of Transportation. Fully coupled thermal-stress analyses were conducted using the FEM to predict the failure mechanisms and the “fire resistance limit” of the superstructure under extreme thermal loading conditions. Furthermore, damage simulations of the FRP deck as a result of snow and ice plowing process were performed to investigate any possibility of bridge failure after damage occurs. Thermal simulations showed that FRP bridge decks are highly sensitive to the effect of elevated temperatures. The FRP deck approached the fire resistance limit at early stages of the fire incident under all cases of fire scenarios. The damage simulations due to the snow plowing showed minimal possibility of bridge failure to take place under the worst-case damage scenario when the top 5 mm of the FRP deck surface was removed. The results of both phases of simulations provide an insight into the safety and the reliability of the FRP systems after the stipulated damage scenarios were considered. Moreover, this paper provides discussions concerning the recommended immediate actions necessary to repair the damaged region of FRP deck panels and possible use of the bridge after the damage incident.     

Approximate Series Solution for Analysis of FRP Composite Highway Bridges

The design of a deck-and-stringer bridge system is usually reduced to the analysis of a T-beam section, loaded by concentrated loads corresponding to an equivalent fraction of the applied truck load. This equivalent load is defined by wheel load–distribution factors, which approximate the overall behavior of the bridge superstructure. In this paper, a one-term approximation of a macroflexibility series solution including deformations for fiber-reinforced polymer (FRP) deck-and-stringer orthotropic bridge systems, is used to develop explicit expressions for symmetric and asymmetric load distribution factors. It is significant that the equations presented herein include important parameters that represent, as accurately as possible, the response characteristics of the super structure, such as the geometry and material properties of the FRP deck and stringers, bridge aspect ratio, and number and spacing of stringers. As an illustration in actual design applications, the formulation presented in this paper is used to develop an analytical method for FRP deck-and-stringer bridge systems, and the method is verified by predicting the response of an all FRP model bridge in the lab and an FRP deck on steel stringers in the field. The results of the present formulation compare well with experimental lab and field results. The simplified analysis presented in this paper can be used with sufficient accuracy for the design of composite FRP deck on stringers bridges.     

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.     

Influence of Reinforcement on the Behavior of Concrete Bridge Deck Slabs Reinforced with FRP Bars

This paper presents the results of an experimental study to investigate the role of each layer of reinforcement on the behavior of concrete bridge deck slabs reinforced with fiber-reinforced polymer (FRP) bars. Four full-scale concrete deck slabs of 3,000?mm length by 2,500?mm width and 200?mm depth were constructed and tested in the laboratory. One deck slab was reinforced with top and bottom mats of glass FRP bars. Two deck slabs had only a bottom reinforcement mat with different reinforcement ratios in the longitudinal direction, while the remaining deck slab was constructed with plain concrete without any reinforcement. The deck slabs were supported on two steel girders spaced at 2,000?mm center to center and were tested to failure under a central concentrated load. The three reinforced concrete slabs had very similar behavior and failed in punching shear mode at relatively high load levels, whereas the unreinforced slab behaved differently and failed at a very low load level. The experimental punching capacities of the reinforced slabs were compared to the theoretical predictions provided by ACI 318-05, ACI 440.1R-06, and a model proposed by the writers. The tests on the four deck slabs showed that the bottom transverse reinforcement layer has the major influence on the behavior and capacity of the tested slabs. In addition, the ACI 318-05 design method slightly overestimated the punching shear strength of the tested slabs. The ACI 440.1R-06 design method yielded very conservative predictions whereas the proposed method provided reasonable yet conservative predictions.     

Analysis of an Orthotropic Deck Stiffened with a Cement-Based Overlay

Over the past years, with increasing traffic volumes and higher wheel loads, fatigue damage in steel parts of typical orthotropic steel bridge decks has been experienced on heavily trafficked routes. A demand exists to find a durable system to increase the fatigue safety of orthotropic steel bridge decks. A solution might be to enhance the stiffness of the traditional orthotropic bridge deck by using a cement-based overlay. In this paper, an orthotropic steel bridge deck stiffened with a cement-based overlay is analyzed. The analysis is based on nonlinear fracture mechanics, and utilizes the finite-element method. The stiffness of the steel deck reinforced with an overlay depends highly on the composite action. The composite action is closely related to cracking of the overlay and interfacial cracking between the overlay and underlying steel plate (debonding). As an example, a real size structure, the Far? bridges located in Denmark, are analyzed. The steel box girders of the Far? bridges spans 80?m, and have a depth of 3.5?m, and a width of 19.5?m. The focus of the present study is the top part of the steel box girders, which is constructed as an orthotropic deck plate. Numerous factors can influence the cracking behavior of the cement-based overlay system. Both mechanical and environmental loading have to be considered, and effects such as shrinkage, temperature gradients, and traffic loading are taken into account. The performance of four overlay materials are investigated in terms of crack widths. Furthermore, the analysis shows that debonding is initiated for a certain crack width in the overlay. The load level where cracking and debonding is initiated depends on the stress-crack opening relationship of the material.     

Structural Characterization of Hybrid Fiber-Reinforced Polymer-Glulam Panels for Bridge Decks

The structural characterization of hybrid fiber-reinforced polymer (FRP)–glued laminated (glulam) panels for bridge deck construction is examined using a combined analytical and experimental approach. The structural system is based on the concept of sandwich construction with strong and stiff FRP composite skins bonded to an inner glulam panel. The FRP composite material was made of E-glass reinforcing fabrics embedded in a vinyl ester resin matrix. The glulam panels were fabricated with bonded eastern hemlock vertical laminations. The FRP reinforcement was applied on the top and bottom faces of the glulam panel by wet layup and compacted using vacuum bagging. An experimental protocol based on a two-span continuous bending test configuration is proposed to characterize the stiffness, ductility, and strength response of FRP-glulam panels under simulated loads. Half-scale FRP-glulam panel prototypes with two different fiber orientations, unidirectional (0°) and angle-ply (±45°), were studied and the structural response correlated with control glulam panels. A simple beam linear model based on laminate analysis and first-order shear deformation theory was proposed to compute stiffness properties and to predict service load deflections. In addition, a beam nonlinear model based on layered moment-curvature numerical analysis was proposed to predict ultimate load and deflections. Correlations between experimental results and the two proposed beam models emphasize the need for complementing both analytical tools to characterize the hybrid panel structural response with a view toward bridge deck design.     

Filament-Wound Glass Fiber Reinforced Polymer Bridge Deck Modules

The demand for the development of efficient and durable bridge decks is a priority for most of the highway authorities worldwide. This paper summarizes the results of an experimental program designed to study the behavior of an innovative glass fiber reinforced polymer (GFRP) bridge deck recently patented in Canada. The deck consisted of a number of triangular filament wound tubes bonded with epoxy resin. GFRP plates were adhered to the top and bottom of the tubes to create one modular unit. The experimental program, described in this paper, discusses the evolution of two generations of the bridge deck. In the first generation, three prototype specimens were tested to failure, and their performance was analyzed. Based on the behavior observed, a second generation of bridge decks was fabricated and tested. The performance was evaluated based on load capacity, mode of failure, deflection at service load level, and strain behavior. All decks tested exceeded the requirements to support HS30 design truck loads specified by AASHTO with a margin of safety. This paper also presents an analytical model, based on Classical Laminate Theory to predict the load-deflection behavior of the FRP decks up to service load level. In all cases the model predicted the deck behavior very well.