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The production of wind energy worldwide has increased 20-fold since 2001. Composite material wind turbine blades are beginning to come out of service in large numbers. In general, these de-commissioned structures, composed primarily of glass fibers in a thermoset matrix and generally between 13 and 80 m long, are demolished and either landfilled or incinerated. This research seeks to establish structural re-use applications for wind turbine blades in civil engineering infrastructure. This paper presents design concepts along with materials and engineering analysis for high voltage electricity transmission structures made from re-used wind turbine blades. This re-use application targets wind blades in the 25 to 50-m overall length range, with single blades considered for use as cantilevered poles, and multiple blades used as replacements for waist-type truss or guyed towers. Strengths of the composite materials are established from coupons cut from de-commissioned wind blades – and section properties are established from blade geometries acquired using LiDAR scanning, through proprietary algorithms developed as part of the research effort. The section analysis is based on two common commercially available blades in the European and U.S. markets: the Vestas V52 and the Clipper C96. The paper reports on preliminary strength design allowables for the typical wind blade laminates and uses these as the basis for design under gravity, wind, and ice loading. Preliminary design of connections and physical mockup testing of these connections are presented.

This paper focuses on the conceptual use of a fiber-reinforced polymer (FRP) wind turbine blade that is repurposed for a second life as an electrical transmission pole. Thousands of tons o...

A wind turbine blade shell made of glass fiber reinforced polymer (GFRP) composite materials was mechanically processed into slender elements referred to as “Needles”. The Needles were used to replace 5% and 10% of the coarse aggregate, by volume, in concrete mixtures that were tested to investigate a number of important properties of fresh and hardened concrete. It was found that the Needles did not affect the stability and workability of fresh concrete negatively. Although the incorporation of the Needles did not have a notable effect on compressive, tensile, and flexural strength of concrete, it resulted in a significant increase in energy absorption capacity (toughness) from 1.2 J in control specimens up to 33.3 J in those with 10% Needle replacement. A polymer burn-off test revealed that, due to the directions in which the shell was cut, in most of the Needles glass fibers were perpendicular to the Needle axis, and therefore to the tensile stress carried by the Needles. Although the Needles with transversely-aligned fibers improve the mechanical performance of concrete, if the cutting directions of wind blades can be optimized so that in the majority of the Needles the fibers are primarily aligned longitudinally, improvements are expected to be more significant.

The production of fiber reinforced polymer (FRP) composite materials is a major source of non-degradable waste. The use of FRP bars for reinforcing concrete is increasing in construction. This study investigates the impact of replacing coarse natural aggregate (NA) in concrete with cut FRP bar waste (FRP-RA) on the compressive and tensile strength of both high strength and normal strength concretes. Concrete cylinders without any FRP-RA, with 40% of NA (the large-grade particles) replaced with FRP-RA, and with 100% of NA replaced with equivalently graded FRP-RA were tested. The results show that the effect of the FRP-RA on the mentioned mechanical properties depends on the concrete strength, replacement ratio and the gradation-size of the NAs replaced. High-strength concrete performed better than low strength concrete and replacement of larger sized NA with FRP-RA resulted in better performance compared to full replacement. The test results show that existing empirical models can sometimes overestimate the tensile strength of lower-strength FRP-RA concretes. The findings show that although the use of FRP waste in concrete reduces the strength, concrete with structural grade mechanical properties can be produced with FRP-RA. The potential durability issues of FRP-RA concrete are discussed and future studies on this topic is proposed.

Shear failure of reinforced concrete members is brittle and catastrophic, and should be avoided. This work presents a comparative study of concrete beams with natural crushed stone and those incorporating recycled concrete aggregate (RCA). The study indicates that the equation presented in ACI 318-14 Code requirements for predicting the shear strength of concrete is less conservative for RCA concrete beams. The presented experimental investigations show that strengthening with fiber reinforced polymer (FRP) fabrics can be designed so that the shear capacity of the beams with weaker (RCA) concrete is higher than that of the control beams with natural aggregate concrete. The design of the FRP strengthening system and the reasons for the effectiveness of the design are explained.

This paper presents a new type of discrete reinforcing element for concrete produced from either waste or new pultruded fiber-reinforced polymer (FRP) composite materials. These elements, r...

For the last three decades, fiber reinforced polymer (FRP) composite materials have been widely used in major engineering industries. Managing FRP waste is becoming an important issue due to the growth in the production of FRP composite materials. In this article, the issue of FRP waste management is discussed and the commonly used methods for the handling of FRP waste are reviewed. One potentially viable use of FRP waste is in the partial replacement of fillers or aggregates in cementitious materials (particularly portland cement mortar and concrete). A number of important prior investigations performed on the use of FRP waste in concrete and mortar are reviewed. The results from most of those investigations suggest that FRP aggregates significantly reduce the strength of cementitious materials with little significant effect on durability. Recommendations for future research in this area are provided for producing stronger mortars and concretes incorporating FRP production and end-of-life waste.

This paper describes an experimental program designed and executed to investigate the failure mode and ultimate capacity of web-reinforced pultruded FRP beams subjected to concentrated loads in the plane of the web. Six 203.2 mm × 101.6 mm × 12.7 mm beams and five 203.2 mm × 203.2 mm × 9.5 mm beams manufactured with vinylester resin were strengthened with one of three systems and subjected to concentrated loads applied directly to the top flange. The three systems were (a) full-depth web bearing stiffeners, (b) “doubler” plates attached to the web, or (c) stiffening elements applied to the upper (loaded) web-flange junction of the specimen. Experimental results showed that the junction stiffeners (58.7%), bearing stiffeners (52.8%), and “doubler” plates (31.7%) all increased the ultimate capacity of the beams when compared to unstrengthened control beams. Beams prepared with bearing stiffeners and “doubler” plates failed in the same manner as the control beams (shear “wedge” failure at loaded web-flange junction), while failure in the beams with reinforced loaded web-flange junctions occurred in the bottom flange near the simple supports. Digital image correlation software was used to capture out of plane displacement of the web and confirms the modes of failure.

The purpose of this paper is to provide a review of and observations on progressive failure and ductility of fiber-reinforced polymer (FRP) composites of interest to civil and infrastructure construction applications. The primary reason for this is that although FRP composites have over the last 25 years successfully penetrated niche markets in civil engineering applications, one of the most frequently heard concerns from designers is their discomfort with the ductility of these composites and the structures built or reinforced with them, and that if the market for FRP applications in construction is to be expanded, the community must address this issue in greater depth. One approach is to use systemwide, structural, progressive failure behavior of the composite material itself to dissipate internal strain energy in lieu of the elastoplastic behavior of metallic materials. Specific applications of FRP composites in construction where progressive failure mechanisms have been considered are reviewed. These include FRP profiles, FRP frame connections, FRP reinforcing bars, externally bonded FRP or mechanically fastened FRP strengthening strips, and FRP column wraps. DOI: 10.1061/(ASCE)CC.1943-5614.0000355. © 2013 American Society of Civil Engineers. CE Database subject headings: Ductility; Energy dissipation; Progressive collapse; Pultrusion; Structure reinforcement; Composite materials; Construction. Author keywords: Crashworthiness; Ductility; Energy dissipation; Progressive failure; Pultruded profiles; Rebars; Strengthening; Wrapping.

The objective of the research reported in this paper was to investigate the use of short arc-length segments and semi-circular segments of paperboard (also known as cardboard) tubes as formwork in bridge deck applications for either long-span [20–50 m (60–160 ft)] steel or prestressed concrete bridges or short-span [6–20 m (20–60 ft)] “Beam-in-Slab” bridges. In both these types of structures conventional plywood and light framing lumber formwork can be expensive and time consuming to install. For over 30 years, paperboard tubes have been used throughout the world to form round, reinforced concrete columns or occasionally voided slabs. These tubes (also know as Sonotubes) are produced throughout the world, and are preferred to conventional steel, plywood, or even fiber reinforced plastic (FRP) formwork because they are economical, disposable and recyclable. Due to their tubular shapes they have not been considered for use in “flat” elements such as slabs and walls. This paper presents results of a series of laboratory tests conducted at the University of Wisconsin – Madison that demonstrate that paperboard tube segments can be used as formwork for certain types of slabs, particularly for bridge decks and a variety of other types of construction where a flat surface is not essential. The testing, which was intended to simulated construction site loading conditions, included ultimate and service load tests, as well as impact loading. Tests were also conducted to investigate how moisture content affects the structural performance of the tubes. Results showed that commercially produced large diameter paperboard tubes may well be viable economical and recyclable materials for forming concrete elements, particularly those used in bridge decks when wide-flange prestressed girders are used.

The use of pultruded fiber reinforced polymer (FRP) grids is being investigated as tensile reinforcement in concrete bridge decks. Three full scale simply supported concrete slabs reinforced with double layer pultruded FRP girds representing long span bridge decks were tested. Punching shear was the critical failure mode. The punching shear capacity was compared to the University of Wisconsin punching shear equation, developed for the grid system on shorter spans by Jacobson (2004), and the punching shear capacity as given by ACI 440 (2006). The Jacobson equation conservatively predicted the capacity for slabs with edge restraint and accurately predicted the punching shear capacity for slabs without edge restraint. The ACI 440 (2006) punching shear equation underestimated the punching shear capacity of the slabs.

Results of the behavior of pultruded fiber-reinforced polymer (FRP) I-shaped beams subjected to concentrated loads in the plane of the web are presented. Twenty beams with nominal depths from 152.4 to 304.8 mm were tested in three-point bending with a span-to-depth ratio of four. Load was applied to the top flange directly above the web—12 without bearing plates and 8 with bearing plates of varying width and thickness. All test specimens failed with a wedgelike shear failure at the upper web-flange junction. Finite-element results support experimental findings from strain gauge and digital image correlation data. Bearing plates increased beam capacity by 35% or more as a function of bearing plate width and thickness. Bearing plates increased average shear stress in the web at failure from 17.4 to 27.2 MPa—below the accepted value of in-plane shear strength (69 MPa). A design equation is presented, and predicted capacities are compared with experimental results. The average value of experimental capacity t...

Fiber-reinforced polymer (FRP) pultruded profiles are produced by a number of manufacturers worldwide in similar, but nonstandard, wide-flange, I, angle, and tubular profiles. At present there is no American National Standards Institute approved design code in the United States for structural design with pultruded FRP profiles. Manufacturers of pultruded profiles each provide their own design equations, design methods, material properties, and safety factors for their pultruded products. There is a need for standardization of production and design of pultruded profiles to enable mainstream use of these profiles in structural engineering practice. The purpose of this paper is twofold: (1) to provide appropriate resistance factors ( ϕ factors) for wide-flange pultruded columns that are compatible with ASCE 7 load factors and (2) to provide a unified analytical equation for local and global buckling of concentrically loaded axial members, which may be appropriate for a future design code. The resistance fact...

Studies on two novel uses of hybrid structural members consisting of commercially produced glass reinforced pultruded ribbed fiber reinforced polymer (FRP) planks and concrete are discussed in this paper. Pultruded planks are produced by all the major pultruders in the world and are utilized primarily as decking for platforms. These highly optimized panels have the potential to be used in many other infrastructure applications, but their flexural stiffnesses have generally been too low to be used in highway and pedestrian bridges due to current span requirements. However, when used “compositely” with concrete or cementitious materials in a hybrid form they have the potential to be much more widely used. Two research studies conducted on two possible hybrid systems of different structural depths are discussed in this paper. The first study describes the use of pultruded planks as permanent formwork in highway bridge decks where the plank is used with concrete to produce a solid slab of 200 mm depth that is typical of slabs seen in highway bridge decks. The second study describes the use of pultruded planks in pedestrian bridge decks where the pultruded plank is used with a cement-board or a cast-in-place concrete panel to produce a hollow slab of 75 mm depth that is typical of timber decking used in FRP pedestrian bridges. Tests were conducted on beam-type specimens of the hybrid slabs to investigate the load transfer mechanisms between the pultruded plank and the cementitious “overlays” for both the 75 mm and 200 mm depths. From analysis of the load-carrying capacity and failure mechanisms of the hybrid slabs it was concluded that such hybrid slabs are viable systems for both highway and pedestrian bridge decks. A bridge deck using the 200 mm deep hybrid slab system was recently constructed on a highway in Wisconsin, USA.

This paper discusses the development of a model design and construction specification for thin [less than 38 mm (1.5 in.)] non-participating permanent formwork panels (also known as, stay-in-place forms and lost forms) made of FRP or FRC materials with or without non-metallic reinforcements for use in the construction of concrete slabs, in particular, highway bridge decks. The use of such forms is motivated by the narrow gaps [less than 1 m (39.4 in.)] that are often found between the flanges of wide flange ‘‘bulb-T” prestressed girders that are becoming commonplace in the US highway construction industry. Bridge contractors have expressed an interest in using non-participating permanent forms to reduce the time and cost required in forming and stripping the plywood forms for such narrow gaps. A model specification that was developed to enable engineers to design and specify such forms is provided in the appendix to this paper. To develop the specification, different permanent formwork panels were fabricated and tested. These included (1) flat cementitious panels reinforced with short glass or polypropylene fibers, (2) flat cementitious panels reinforced with bi-directional FRP thin grids, (3) flat cementitious panels reinforced with unidirectional FRP reinforcing bars, and (4) off-the-shelf, commercially manufactured pultruded FRP thin-walled, ribbed planks. The specification provides guidance for the width of gaps permissible for each Class of system and details of prescriptive and performance tests that must be performed to qualify the products for use in construction.

The investigation of a structural fiber-reinforced-polymer (FRP) stay-in-place (SIP) form used to construct and reinforce a deck for a prototype military bridge system is discussed in this paper. For this application the deck is subjected to combined bending and compressive longitudinal axial load because it also serves as the top chord of the truss for the bridge system. In an experimental program, deck specimens were tested in several configurations. The results are compared to ACI 440 design guide equations, and capacity prediction techniques are proposed for limit states associated with flexural and flexural-shear under the combined loading. It was found that the ACI 440 equations accurately predicted the flexural and flexural-shear capacities under combined loads provided that eccentricity due to the combined loading was accounted for in the calculations.

Attaching reinforcing material such as steel or fiber reinforced polymer (FRP) plate to the external face of concrete members is a conventional technology used for strengthening concrete structures. Generally, three mechanisms are involved in the composite action between the concrete and the attachment: adhesion, dowel action, and friction. Methods have been developed for the identification of the interfacial bond properties when only one or two mechanisms exist at the interface. However, the existing methods cannot be used when all three mechanisms coexist. A methodology for testing the bond and the corresponding data interpretation procedure are proposed in this work to identify the bond properties of the interface involving all bonding mechanisms. As the bonding mechanisms are coupled and interact with each other, it is impossible to test all of them individually and separately. The proposed test protocol involves an analytical procedure that decouples individual mechanisms from the global response curves. Furthermore, conventional bond test methods involve extensive and labor-intensive strain gauging as well as complicated data regression analyses of test results in order to obtain the bond properties. The proposed method requires only the simplest instrumentation to measure displacement and load, without strain gauging. Test data processing also involves simple graphical interpretations only, without complicated and tedious mathematical data regression analyses. Therefore, the proposed method has advantages over the existing ones and can be easily adopted in engineering practice.

A feasibility study in which the use of a commercially produced pultruded fiber reinforced polymer (FRP) plank for both permanent formwork and secondary or primary tensile reinforcement of a concrete structural member is described in this paper. To achieve satisfactory bond at the interface between the smooth surface of the FRP plank and the concrete, two kinds of aggregate, gravel and sand, were epoxy bonded to the planks. Concrete beams using the aggregate-coated FRP planks were fabricated and tested. Satisfactory bond between the FRP plank and the concrete was developed which was evidenced by numerous well-distributed flexural cracks, and ultimate capacities of the aggregate coated FRP plank specimens greater than the steel rebar reinforced control specimen. ACI 440 equations were found to provide good predictions of the flexural strengths but poor predictions of the shear strengths of the FRP plank reinforced beams. ACI 318 equations, however, provided good shear strength predictions.

The analytical model for reinforced concrete beams strengthened using mechanically-fastened fiber reinforced polymer (MF-FRP) pultruded strips is discussed in this paper. In this method, FRP strips, reinforced with a combination of carbon and E-glass unidirectional fibers and continuous strand mats, are fastened to the concrete with steel powder-actuated (PA) fasteners and expansion anchors (EA). The model predicts the ultimate strength and failure modes of MF-FRP strengthened beams and was developed based on results of tests on over 75 RC beams of many different sizes using the MF-FRP method, that have been conducted over the last five years. These tests have explored numerous different failure modes and factors affecting the behavior of MF-FRP strengthened beams. The analytical model can be used to proportion the strengthening system for an RC beam so as to cause the beam to fail in a unique ductile failure mode. This procedure was used to proportion strengthening systems for large-scale beams (7.3 m long by 51 cm × 51 cm) that were used to verify the analytical procedure. The strengthened RC beams were designed to fail in a ductile manner. In the test results presented in this paper, the strengthened beams showed increases in yield and ultimate moments of up to 25% and 58%, respectively over an unstrengthened beam. All strengthened beams failed, as intended, in a ductile manner with the ultimate failure mode due to concrete compression failure at large deflections with the FRP strip still firmly attached. Comparisons between the analytical predictions and the experimental results show good agreement.

We perform an experimental study of concrete beam with pultruded fiber reinforced polymer(FRP) plank using as a permanent formwork and the tensile reinforcement. A satisfactory bond at the interface between the smooth surface of the pultruded plank and the concrete must be developed for the FRP plank and the concrete to act as a composite structural member. Two kinds of aggregate were bonded to the FRP plank using a commercially available epoxy. No additional flexural or shear reinforcement was provided in the beams. For comparison we test two types of control specimen. One control did not have any aggregate bonded to the FRP plank and the other control had infernal steel reinforcing bars instead of the FRP plank. The beams were loaded by central patch load to their ultimate capacity. The experimental results were compared to current ACI 318 (2005) and ACI 440 (2006) code predictions. This study demonstrates that the FRP plank has the potential to serve as formwork and reinforcing for concrete structures.

A concise state-of-the-art survey of fiber-reinforced polymer (also known as fiber-reinforced plastic) composites for construction applications in civil engineering is presented. The paper is organized into separate sections on structural shapes, bridge decks, internal reinforcements, externally bonded reinforce ments, and standards and codes. Each section includes a historical review, the current state of the art, and future challenges., the published version in ASCE's Civil Engineering Database(http://cedb.asce.org)

This paper describes the use of FRP materials as reinforcements and formwork for a concrete highway bridge deck. It describes the construction process and provides a cost analysis of the project. A continuing research program at the University of Wisconsin–Madison is developing concepts for bridge decks reinforced with fiber reinforced polymers (FRP). This project involved the implementation of one of these concepts in a major highway bridge. Three forms of FRP reinforcing were combined to reinforce the concrete deck: FRP stay-in-place (SIP) forms, deformed FRP reinforcing bars (rebars), and a special prefabricated pultruded FRP reinforcing grid. The research project, supported by the Innovative Bridge Research and Construction Program (IBRC) in the United States, resulted in the construction of a two-span highway overpass on US Highway 151 in Wisconsin. Based on the analysis of the short-term material and labor costs it appears that given the savings in construction time and their potential long-term durability and maintenance benefits, FRP reinforcements for bridge decks may be cost-effective, notwithstanding their currently high initial costs. Optimization of FRP stay-in-place formwork is recommended to decrease the cost of the FRP reinforcing system in the future.

This paper presents a case study of prefabricated double-layer pultruded fiber-reinforced polymer (FRP) grids for bridge deck construction. These grids were used to reinforce a 39.6 m long by 13.7 m wide (130 by 45 ft ) bridge deck on US Highway 151 over the De Neveu Creek in Wisconsin. The Federal Highway Administration Innovative Bridge Research and Construction Program invested resources in this program to investigate new uses for off-the-shelf technologies in constructing highway bridges. The feasibility of modifying manufacturing techniques to create innovative double-layer, 3D pultruded, FRP grids measuring 12.9 m long by 2.4 m wide by 16.5 cm deep ( 42 ft 6 in. by 8 ft by 6 1/2 in.) was investigated. In addition, the feasibility of placing the grids rapidly and constructing a bridge deck was also demonstrated. The FRP grids were required to meet a prescriptive material specification and a structural performance specification. Shear connectors were designed by the manufacturer to join large top and ...

A new method has been developed for strengthening reinforced concrete beams for flexure which uses multiple mechanical fasteners to attach a fiber reinforced polymer (FRP) strip to the member. This study investigates the behavior of the method on full scale concrete T beams of three different steel reinforcement levels. The beams were strengthened without surface preparation, and the strips were attached with only four man-hours of labor per beam. The strengthened beams resulted in increases of up to 11.7 % in the yield moment and up to 27.2 % in the moment capacity at a deflection of L/135. The beams exhibited large amounts of ductility, before failure.

The current method of bonding fiber-reinforced polymer (FRP) strengthening strips to concrete structures requires extensive time and semiskilled labor. An alternative method is to use a commercial off-the-shelf powder-actuated fastening system to attach FRP strips to concrete. A series of flexural tests were conducted on 15 304.8×304.8×3,657.6mm (12×12×144in.) reinforced concrete beams. Two beams were tested unstrengthened, 12 were strengthened with mechanically fastened FRP strips, and one was strengthened with a bonded FRP strip. The effects of three different strip moduli, different fastener lengths and layouts, and predrilling were examined. Three of the beams strengthened with mechanically attached FRP strips showed strengthening comparable to the beam strengthened with a bonded FRP strip. The same three beams strengthened with mechanically attached FRP strips also showed a greater ductility than the beam strengthened with a bonded FRP strip.

A proposed model specification for FRP composite materials for use in civil engineering structural systems is described in this article. The model specification provides a classification systems for FRP materials, describes admissible constituent materials and limits on selected constituent volumes, describes tests for specified mechanical and physical properties, specifies limiting values of selected properties in the as-received condition and in a saturated state, and provides a protocol for predicting long-term property values subjected to accelerated aging based on the Arrhenius model. The model specification is included as an appendix to the article.

The Editorial Board of the American Society of Civil Engineers Journal of Composites for Construction~Lawrence C. Bank, Editor! sponsored a survey of the civil/structural engineering programs around the world on the subject of fiber reinforced polymer ~FRP! composites, excluding the traditional steel-concrete composite construction and fiber reinforced concrete. This paper summarizes the main results from the survey. During the last decade, considerable focus has been devoted to the use of FRP composites in construction. The main driving force is the need for revitalizing the aging infrastructure with innovative materials and structural systems that last longer and require less maintenance. As the construction industry embraces FRPs in the field, the need for educating civil engineers with background on the subject has become more evident. Despite a significant number of field applications and laboratory research, the survey shows that FRPs have not yet been fully implemented in the engineering curricula, and the classrooms are still lagging behind. To improve this situation, civil engineering and their extension programs must provide sufficient training on unique features of FRPs so that engineers could design or specify them in construction. This survey should be repeated as a gauging tool again at the end of this decade.

Recycling glass fiber reinforced polymer (GFRP) composite materials has been proven to be challenging due to their high mechanical performance and high resistance to harsh chemical and thermal conditions. This work discusses the efforts made in the past to mechanically process GFRP waste materials by cutting them into large-sized (cm scale) pieces, as opposed to pulverization, for use in concrete mixtures. These pieces can be classified into two main categories—coarse aggregate and discrete reinforcement, here referred to as “needles.” The results from all the studies show that using GFRP coarse aggregate leads to significant reductions in the compressive strength and tensile strength of concrete. However, GFRP needles lead to sizable increases in the energy absorption capacity of concrete. In addition, if the glass fibers are longitudinally aligned within the needles, these elements can substantially increase the tensile strength of concrete. Processing GFRP waste into needles requires less energy and time than that for producing GFRP coarse aggregate. Also, compared to pulverized GFRP waste, which consists of broken and separate particles of glass and resin that at best can be used as low-quality fillers, GFRP needles are high strength composite elements.

A description is given of laboratory testing, initial test results, and continuing research to develop design procedures and plans for construction of a two-span highway overpass on US-151 in the state of Wisconsin using only a fiber-reinforced polymer (FRP) reinforcement system in the concrete bridge deck. The use of FRP reinforcing is being pursued to increase the durability of bridge decks and to reduce unit cost and time. The unique aspect of the new bridge is that it will use FRP stay-in-place formwork, placed over precast concrete I girders, to serve as formwork and as the bottom transverse reinforcement of the bridge deck. In addition, a heavy-duty prefabricated FRP grid will be used for the top layer of concrete reinforcing. Full-scale prototype laboratory testing is being used to develop design recommendations including effective distribution widths. From the spring to fall of 2003, a construction productivity study comparing the FRP deck construction sequence with that of identical adjacent steel reinforced deck will be conducted. Both bridges will be field load tested before opening to traffic. The FHWA Innovative Bridge Research and Construction Program is supporting the research and construction.

A model specification for fiber-reinforced polymer (FRP) composite materials for use in civil engineering structural systems was developed. The model specification provides a classification system for FRP materials, describes admissible constituent materials, and specifies limits on selected constituent volumes. The specification provides procedures for qualifying FRP composite laminates and for accepting FRP composite parts constructed of qualified laminates. Test methods to obtain mechanical and physical properties were devised, along with stipulation of limiting values for selected properties for both laminates and parts. Based on the Arrhenius model, a protocol was outlined for predicting long-term property values subjected to accelerated aging.

The state-of-the-art of fiber-reinforced polymer (FRP) composite stay-in-place (SIP) structural form systems for bridge decks is presented in this paper. This technique involves constructing a concrete deck whereby prefabricated FRP components act as both the permanent formwork and the bottom flexural reinforcement. The advantages and limitations of the technology are presented, along with the current progress of experimental and analytical investigations. Extensive laboratory investigation is presented covering numerous aspects of the system, including strength, fatigue, and environmental performance. A variety of system configurations are discussed. Examples of field applications are presented, along with evaluations of cost effectiveness and inspection considerations. The result of these investigations show that FRP SIP formwork systems can be both constructible and meet applicable code requirements for strength and serviceability. Preliminary cost assessments suggest that increases in material costs can be partially offset by savings in labor during installation. Finally, future research needs are identified.

Five 609.5-mm deep fiber-reinforced polymer (FRP) beams with a span-to-depth ratio of 4∶1 were tested in three-point bending with the beam ends constrained to prevent global failure. A concentrated load was applied at midspan either directly to the top flange or through a 101.6 mm wide by 12.7-mm thick FRP bearing plate resting on the top flange. VIC-3D Digital Image Correlation Measurement Software from Correlated Solutions captured out-of-plane displacement of the webs, and Southwell plots were generated to determine buckling loads. Each specimen experienced a stability failure of the web before undergoing material failure in the upper web-flange junction. On average, web buckling occurred at 90% of the ultimate load. The introduction of a bearing plate did not significantly affect the buckling load or ultimate capacity of the specimens. One specimen was tested into the postbuckling range, unloaded, and reloaded to material failure and experienced no loss of strength or stiffness. Another specim...

Fiber-reinforced polymer (FRP) composite materials are being used to develop products for use as highway appurtenances, such as, sign supports, luminaire supports and guardrails (crash barriers). These structures, that are located alongside highways and roads, are subjected to vehicular impacts and must be designed to be ‘crashworthy’ to ensure the safety of the driving public. This paper reviews an ongoing 10-year research and development program funded by the United States federal highway administration (FHWA) and the United States department of transportation (DOT) to produce a crashworthy composite material highway guardrail system. An overview of the research and development leading to a patented pultruded composite material guardrail is provided.

The preliminary design of a floating causeway system made from pultruded composite materials is described. As part of the design effort a 24-ft long × 15-ft wide × 5-ft high (7.3 m × 4.6 m × 1.5 m) pultruded GFRP scaled prototype was fabricated. Details of, and selected results from, the experimental testing and finite element modeling of this prototype are given. Testing revealed that the prototype composite structure was capable of supporting the expected service sustained loads, as well as, the lifting loads. Strain and deflection data indicated that minimal stress levels existed in the structure during testing. For predictive and comparative purposes, two finite element models were developed that corresponded to the sustained load and lifting load tests. These were relatively simple two-dimensional models, however, they effectively captured global and localized structural behavior.

The bond properties of fiber reinforced polymer (FRP) reinforcing bars (rebars) at temperatures ranging from room temperature (20°C) to high temperatures of up to 250°C are discussed in this paper. The bond properties in this temperature range were studied for a number of commercially produced rebars, where different bond “treatments” were applied to FRP rebars. Test results showed a reduction of between 80 and 90% in the bond strength as the temperature increased from 20 to 250°C. In comparison, ordinary deformed steel rebars showed a reduction of only 38% in the same temperature range. In addition, a reduction in the bond stiffness, which was determined from the slope of the ascending branch of the pullout load versus slip curve, was seen as the temperature increased. At elevated temperatures the postpeak bond decrease was gradual as compared with the instantaneous drop at room temperature. Greater sensitivity to high temperatures was seen in FRP rebars, in which the bond relies mainly on the polymer treatment at the surface of the rod.

This paper presents a quantitative economic analysis and a qualitative constructability analysis of three-dimensional fiber-reinforced plastic (FRP) reinforcement cages for concrete beams. Material, labor, and life-cycle costs are provided, and construction practice aspects are discussed. The results of the analyses indicate that prefabricated FRP cages can offer benefits to the construction industry. Although the initial costs of the FRP materials are likely to be higher than those of steel rebar, there is a significant potential for cost savings due to reduced maintenance and labor costs, as a result of the corrosion resistance of the FRP and the increased construction productivity. When direct life-cycle costs are considered, FRP reinforcements already constitute, in many cases, an economically competitive alternative to conventional steel reinforcement in adverse environments. If, in addition, the indirect cost savings as well as quality and safety issues are considered, the FRP reinforcement may be even more competitive.

An investigation of the local compression flange buckling and failure of pultruded fiber-reinforced plastic (FRP) beams is described in this paper. Results of tests on commercially produced pultruded E-glass/polyester and E-glass/vinylester composite material wide-flange I-beams are described. The beams were tested in a four-point bending configuration in a specially designed fixture which was designed to cause local buckling and ultimate failure of the compression flange of the beams and to avoid global lateraltorsional buckling and local web failure. All beams were monitored with strain gages and LVDTs. Buckling loads, failure loads, buckling stresses, deflections and failure modes are reported. Standard and "customized" pultruded beams in the 8 inch (203 mm) series were tested. Based on an analysis of the performance of the standard 8 x 8 x 3/8 in. (203 x 203 x 9.5 mm) beams, two 8 x 8 x 3/8 in. (203 x 203 x 9.5 mm) beams were "customized." In these "customized" beams the fillet region at the flange and web intersection was altered in order to increase its strength and the rotational stiffness. Analysis of the test results of the customized beams indicated that significant increases in load carrying capacity of pultruded beams can be achieved with minor geometry and fiber architecture modifications to the standard beams. A discussion of the differences in buckling and failure characteristics of the beams based on their resins, sizes, and custom modifications is provided.

The use of Mechanically Fastened Fiber Reinforced Polymer (MF-FRP) laminates is emerging as a viable alternative to adhesively bonded FRP laminates for the rehabilitation of reinforced concrete (RC) members such as beams and slabs. A recently published state-of-the-art review of the experimental research has demonstrated the viability and effectiveness of MF-FRP systems. This paper provides a state-of-the-art review of the analytical and numerical studies performed over the last decade with the aim of: (a) predicting the strength, the load-deformation response and the failure mode of rehabilitated RC members, and (b) accounting for the interfacial behavior between the concrete and the MF-FRP laminate. Ultimate strength models and constitutive models are critically reviewed based on their key assumptions and formulations and compares the analytical predictions with previously reported experimental results.

Technical literature on the subject of environmental exposure effects related to determining accelerated test methods for the prediction of long-term performance of FRP composite materials for highway structural applications is reviewed in this paper. Effects of environmental exposure of a chemical and a thermal nature on fiberreinforced polymer (FRP) composites are considered. Such exposures include temperature, moisture and chemicals in liquid solutions or in gaseous mixtures. The effects include the changes in the physical and mechanical properties of the composite materials. Such changes are typically related to the degradation or deterioration of the composite material. Synergistic effects of mechanical load and exposure are also reviewed. The review is divided in topics entitled Materials, Exposure Conditions, Experimental Techniques, Failure Mechanisms and Theoretical Modeling.

An experimental investigation of the local compression flange buckling and failure of commercially produced pultruded fiber-reinforced plastic (FRP) I-shaped beams is described in this paper. Results of tests on pultruded E-glass/polyester and E-glass/vinylester composite material beams are described. The test configuration was designed to cause local buckling and ultimate failure of the compression flange of the beams and to prevent global lateral-torsional buckling. The beams were stiffened to prevent crippling and warping at the supports, and local tensile failure at the load points. All beams were monitored with strain gages and LVDT’s. Buckling loads, failure loads, buckling stresses, deflections, and failure modes are reported. Effective mechanical properties of the beams, obtained from overall flexural and shear strain data, are presented. A discussion of the different failure characteristics of the polyester and the vinylester beams is provided.

Results of an experimental and analytical investigation of the behavior of a pultruded fiber‐reinforced plastic (FRF) portal frame subjected to short‐term static loads are presented. A 6 ft high by 9 ft wide (1.83m×2.74m) plane portal frame was designed and constructed of glass/vinylester pultruded FRP thin‐walled sections. Data obtained from short‐term load tests on the frame are presented. Failure of the beam‐to‐column connections and compression flange buckling of the girder are discussed. An analytical investigation was performed to predict the nonlinear response of the frame. The numerical model includes the effects of axial, shear, and flexural deformation of the pultruded numbers, flexibility of the beam‐to‐column connections, and the postbuckling of the frame girder. An expression for the nonlinear rotational stiffness of the pultruded beam‐to‐column connection is presented. The experimental data, obtained from the full‐size test, are compared with the analytical model.

The long-term creep and the short-term failure of a plane portal frame structure, constructed entirely of pultruded fiber-reinforced plastic (FRP) components, has been investigated both experimentally and analytically. Two, 6 feet high by 9 feet wide, plane portal frames were designed and constructured using standard “off-the-shelf” glass/vinylester pultruded beams, nuts and threaded rods produced by Creative Pultrusions, Inc. One frame was subjected to a constant long-term load and analyzed for its creep characteristics while the other was tested to failure under short-term loading. The creep analysis considered both the time-dependent response of the FRP structural members and the contribution of shear-deformation effects. The use of viscoelastic moduli in conjunction with a shear-deformable beam theory is detailed. Theoretical predictions are compared with the experimental data. Design recommendations are suggested for structural applications.

The surface degradation of glass fiber-reinforced polymer (GFRP) pultruded rods when embedded in concrete castings and subjected to environmental conditioning is discussed in this paper. Investigation of the degradation of the GFRP rods were performed using optical microscopy and scanning electron microscopy (SEM). Unidirectionally reinforced pultruded rods (6.3- and 12.7-mm diameters) containing E-glass fibers in polyester and vinylester matrices were conditioned at standard laboratory conditions (21 C, 65% relative humidity) or submerged in aqueous solutions (tap water) at 80 C for durations of 14 and 84 days. Observations of the surfaces and cross-sections of the rods by optical microscopy and SEM revealed a variety of degradation phenomena. Embedded hygrothermally conditioned rods were found to have developed surface blisters of different sizes and depths. SEM studies of the surface revealed degradation of the polymer matrix material and exposure and degradation of the fibers close to the surface of the rods. The rods with the vinylester resin matrix showed less extensive degradation than those with the polyester resin matrix; however, the degradation characteristics of the two types of rods appear to be similar.

Many timber trestle railroad bridges in Wisconsin have experienced deterioration and are in need of rehabilitation. In addition, the railroad industry is increasing the weights of cars. The combined effect of heavier loads and deterioration threatens to cut short the service life of timber bridges. One of the most critical problems that has been identified was the overloading of timber piles in bridges, which can be remedied by creating a stiffer pile cap. The goal of this investigation was to show that fiber reinforced polymer (FRP) strips fastened to timber with screws can be used to create composite action between two beams in flexure or truss action between two deep beams. Ultimately this may help redistribute the loads to piles when FRP strips are used as struts on cap beams over short spans. Several test series were conducted with beams in flexure, deep beams over short spans, and full scale specimens to determine the manner in which FRP strips improved the members’ performance. Mechanically fastened FRP strips were effective in developing composite action in slender beams in flexure and truss action in short deep beams.

The in‐plane shear modulus and the in‐plane shear strength of pultruded glass fiber reinforced plastic (FRP) materials were measured using the Iosipescu shear test method. Material specimens, in coupon form, were cut from the webs and flanges of commercially produced polyester and vinylester wide‐flange pultruded beams. The experimental testing procedure is described, and data reduction methods needed to define the shear modulus and the shear strength from the nonlinear stress‐strain curves are discussed. A new method to obtain the in‐plane shear modulus directly from load‐displacement data is proposed. Shear modulus predictions using the proposed method are compared with those obtained from the stress‐strain data.