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This paper demonstrates the concept of adaptive repurposing of a portion of a decommissioned Clipper C96 wind turbine blade as a pole in a power transmission line application. The current research program is aimed at creating a path towards sustainable repurposing of wind turbine blades after they are removed from service. The present work includes modelling and analysis of expected load cases as prescribed in ASCE 74 and NESC using simplified boundary conditions for tangent pole applications. Load cases involving extreme wind, concurrent ice and wind, extreme ice, differential ice, broken conductor, and broken shield have been analyzed and governing load cases for bending, shear, and torsion have been examined. Relative stiffnesses of different parts forming the wind blade’s cross section (i.e., shell, web, and spar cap) are determined. The corresponding stresses associated with each part under the governing loads are compared to allowable strength values which are determined from composite laminate theory and modelling of the known laminate structure of the E-Glass FRP material. Stresses and deflections obtained are compared with governing reliability-based design criteria and code requirements. The results of the structural analysis indicate that the wind blade can resist the expected loads with reasonable safety factors and that the expected deflections are within permissible limits. Recommendations are provided for detailing and modification of the wind blade for a power pole application in which crossarm and davit connections are highlighted, and foundation details are emphasized.

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...

The objective of this research is to demonstrate that parts of decommissioned wind turbine blades can be repurposed for infrastructure applications for a sustainable future of the wind power industry. The purpose of this paper was to develop a methodology to conduct detailed structural engineering design of composite material parts extracted from wind turbine blades. A large section extracted from a 100-m long blade was repurposed as a roof for a small (approximately 40 m2) single-story masonry house. Geometric and material properties were taken from the blade design documents. A three-dimensional graphical model was created from the exterior surface and material layups. The roof was designed using the load and resistance factor design method familiar to civil engineers. Analysis of stresses and defections was conducted using hand calculations and the finite element method. The results of the analyses showed that the roof is within code mandated stress and deflection limits. The methodology developed could be applied to other wind blade repurposing concepts.

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 purpose of the present study is to compare the environmental impacts of using coarse natural aggregate (NA) and coarse recycled concrete aggregate (RCA) to produce concrete in the New York City area, by means of a unique LCA framework that incorporates comprehensive regional data. A comparative environmental impact assessment study was performed on the critical processes of the life cycles of NA and RCA concretes. For this purpose, concrete ready-mix plants, construction and demolition waste (CDW) recycling plants, NA quarries, and other producers and distributers of concrete raw materials, in addition to CDW landfills in the New York City area, were located. NA and RCA concrete mix proportions that result in the same compressive strength of concrete were used. Also, the environmental impact that would be caused if CDW was landfilled rather than processed into RCA was measured. In the New York City area, replacing NA with RCA as a concrete aggregate does not affect the environmental impact of concrete production significantly. However, if CDW is recycled only for the purpose of producing concrete aggregate, the avoided landfilling of the CDW will be a result of producing RCA concrete. When avoided landfilling is accounted for, the magnitude of some of the environmental impact indicators for RCA concrete is significantly lower than those of NA concrete (16 and 17% for acidification and smog formation, respectively). In addition, it was found that the impact from transporting RCA to ready-mix plants is on average 37% less than that caused by transporting NA to the plants. Sensitivity analyses and normalization of the results revealed that the environmental impact of changing the type of concrete aggregate from NA to RCA is negligible compared to the total environmental burden of New York City. If RCA concrete is used for all types of construction projects in the NYC area, achieving a significant reduction in the environmental impacts is unlikely. Future work is needed to study specific projects in the region that are categorized based on demand for transportation and cement (the largest environmental stressors of concrete production) to determine for which type of project the use of RCA concrete has the highest environmental benefits.

This paper describes the use of a system dynamics (SD) computational method to evaluate initial designs or upgrades of security measures to protect a building and its occupants from bioterr...

The production of wind energy worldwide has increased 20-fold since 2001. Composite material wind turbine blades, typically designed for a 20-year fatigue life, are beginning to come out of service in large numbers. In general, these decommission blades, composed primarily of glass fibers in a thermoset matrix, are demolished and landfilled. There is little motivation for recycling the composite materials, as the processes for reclaiming the fibers (solvolysis, pyrolysis) have not been proven to be economically viable. This research seeks to establish structural reuse applications for wind turbine blades in civil engineering infrastructure, hypothesizing that advanced composite materials may be an attractive alternative to conventional infrastructure materials (e.g. steel, reinforced concrete). This paper presents an analysis and materials characterization of a 47 meter Clipper C96 wind blade. The primarily numerical analysis is accompanied by materials characterization taken from an un-used Clipper blade donated to the project from the Wind Turbine Testing Center (WTTC). The paper presents a brief background on wind turbine blade adaptive re-use, proposing a hypothetical load bearing application of the Clipper wind blade as an electrical transmission tower structure carrying axial compression, along with flapwise and edgewise bending forces. The paper summarizes the composite laminates and cross-section geometries of the blade and establishes the axial and flexural stiffnesses of the blade at multiple sections along the blade length. From a first-order estimation of applied loads for the tower application, the resulting stresses in the composite materials are estimated and compared to the design material properties for the wind blade as originally constructed.

This paper presents a method for the digital reconstruction of the geometry of a wind turbine blade from a point-cloud model to polysurface model. The digital reconstruction of the blade geometry is needed to develop computer models that can be used by architects and engineers to design and analyze blade parts for reuse and recycling of decommissioned wind turbine blades. Initial studies of wind-blade geometry led to the creation of an airfoil database that stores the normalized coordinates of publicly-available airfoil profiles. A workflow was developed in which these airfoil profiles are best-fitted to targeted cross-sections of point-cloud representations of a blade. The method for best-fitting airfoil curves is optimized by minimizing the distance between points sampled on the curve and point-cloud cross section. To demonstrate the workflow, a digitally-created point-cloud model of a 100 m blade developed by Sandia National Laboratory was used to test the reconstruction routine.

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.

Dealing with composite waste from decommissioned wind turbine blades will become a major issue in the coming years. This study aims to determine the most sustainable disposal method for Irish blade waste in the next ten years by using life cycle assessment to compare three scenarios: Co-processing in cement kilns in Germany, co-processing in Ireland, and landfill in Ireland. The results of this study establish a baseline impact scenario with which to compare future repurposing solutions, which are higher on the European Waste Hierarchy. Co-processing is not carried out in Ireland at the moment, but as blade waste increases, there is a strong likelihood of it becoming viable. Co-processing utilizes shredded blade waste to replace fuel and raw materials in the production of clinker, whereby environmental gains are made through material substitution. Comparative Life Cycle Assessment is used to determine which scenario is the least environmentally impactful, and which of the variables has the strongest impact. Co-processing in Ireland is determined to be the least impactful, due to the material substitution and the reduced transport. Material substitution is found to have a stronger impact than increased transport between Ireland and Germany. There is, however, a concern with co-processing as a preferred method to dispose of Irish blade waste in that the ease of disposal in this fashion might de-incentivize repurposing. Future research is needed to compare the costs of co-processing to other repurposing ideas, and to develop policy that requires farm owners to set aside bonds to pay for more sustainable second life options for blade waste. This will ensure that the option of co-processing in Ireland is passed over for a more sustainable Irish alternative.

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...

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.

Sustainable recyclable paper and composite materials can be ideal choices for the construction of temporary structures for both exhibition spaces or for rapid-recovery shelters in emergency operations. The unique engineering and sustainable features of these structures need to be considered as an integral part of the design process from the conceptual phase. Engineering studies to analyze these structures should be as important as the overall artistic and architectural vision. This paper examines the use of environmentally creep-formed paper tubes for the design, construction, and exhibition of, “Portals to an Architecture”, a large temporary outdoor sculpture.

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.

The objective of the research described in this article is to improve measurement, prediction and optimization of sustainable building material performance by integrating a decision-making framework for sustainable material selection of building materials with a building information modeling (BIM) tool. Integration of a BIM model with a decision-making tool and sustainable material selection addresses the difficulties of making decisions earlier in the design/build process and allows for specific sustainability trade-off analyses to be conducted, using the actual building conditions and characteristics. It is intended to improve the way building material data is utilized in a building throughout its life cycle, and to model the impact of design, maintenance, operations and occupant behavior modification decisions made in an effort to improve the building’s contribution to a sustainable infrastructure. Pertinent information contained within a BIM model is extracted, and utilized in decision making related ...

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...

This paper presents a decision-making tool based on the system dynamics method for building design and operation, and demonstrates the use of the method for the analysis of a building subjected to a bioterrorist attack. A literature review of prior uses of the system dynamics method, focusing mainly on historic uses within civil and environmental engineering and related disciplines is first presented, to make the case for the applicability of the system dynamics method as a decision-making tool for building system design, retrofit, and operation. A proof-of-concept system dynamics model is presented for modeling of an elementary building system subjected to a bioterrorist attack. The proof-of-concept model includes evaluation of modifications to the building and its defenses. The results of the model simulation are presented and compared with previously published data. Use of the output data to improve decision-making in building design, retrofit, and operation is discussed. A method to link an electronic building information model (BIM) of the building to enable the electronic capture of the relevant building features in the system dynamics model is also discussed and demonstrated. Finally, future development of the model and other potential areas of applicability for the modeling methodology are discussed.

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.

Due to the lack of data and experience with designing buildings for a bioterrorism hazard, it is important for civil engineering professionals to understand both the way that risk is currently accounted for in the design of a building for a bioterrorism hazard and the methods for analyzing risks to buildings that can be borrowed from risk analysis professionals. This paper provides a literature survey of four subject areas dealing with the risk analysis of bioterrorism applied to buildings: 1 perception of the risk of bioterrorism; 2 risk analysis of bioterrorism; 3 risk management of bioterrorism risks; and 4 risk communication of bioterrorism risks, and includes an example of a simple risk analysis process for a hypothetical building. Bioterrorism presents building design engineers with new chal- lenges. It is a very unpredictable hazard, and very little data exist to guide building designers and decision makers in protecting buildings from this hazard. Designing a building with bioterrorist attacks in mind involves many different disciplines, including, for example, structural, mechanical, and electrical engineering, architecture, landscape architecture, security design professions, and law enforcement. Large consequences are possible in the event of a successful attack, and many building design engineers have little or no experience with defending against a bioterrorist attack. It is important that a reasonable process for analyzing and dealing with these risks be established, and that the process include issues of risk perception and communication within the risk analysis framework.

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.

Paperboard tubes have been used in building construction as formwork for concrete columns for over 60 years. Paperboard tubes, typically produced for the sheet or fiber material converting industries, have been used in a number of unique and often prototype architectural and structural engineering application since the late 1980s. This chapter reviews recent developments in paperboard tubes for the construction industry and provides guidance on the analysis and design of paperboard tubes for use in load-bearing architectural and structural engineering applications. Structural system selection, the analysis and design procedures for column, beam, truss, and arch members and connection elements are provided. To provide background, an overview of typical dimensions and uses of paperboard tubes in industrial, construction, and structural applications is provided. The manufacturing technology used to produce tubes is described, and the nonlinear viscoelastic mechanics of paperboard and paperboard tubes are discussed. Special attention is paid to the effect of moisture and temperature on the short- and long-term properties of the paperboard and the tubes.

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.

As buildings have become larger and house more people, political and societal issues have become more complex, and risks associated with occupying buildings have changed. In particular, since the terrorist attacks of 2001, the anxiety levels and perceived risks of building occupants especially occupants of tall, high-profile buildings have increased. These perceived risks include risks of terrorist attacks, natural disasters, the possibility of bomb threats, and catastrophic fires. The public's perception of risk is already incorporated into building design codes and performance-based design PBD methods for such hazards as earthquakes and fires—explicitly in some cases, implicitly in others. Risk perception will clearly need to be addressed in the design of buildings, as trade-offs in "acceptable" risk versus cost must be made. As terrorism represents a constantly changing design challenge, and is a target-specific hazard, as opposed to a location-specific hazard, it seems unlikely that prescriptive code requirements will be entirely effective at addressing this hazard. PBD codes are a promising approach for design issues that deal with such "cutting-edge" concepts.

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 ...

This paper describes research on the evolution of a cost-effective, structural stay-in-place (SIP) formwork bridge deck system with an integrated modular three-dimensional fiber-reinforced polymer (FRP) reinforcement cage. Recent research conducted at the University of Wisconsin is reviewed to show the evolution of the reinforcing system to include an integral FRP SIP form. The evolution occurred through laboratory testing, which was followed by the design and construction of two bridge structures owned by the State of Wisconsin. Each structure used different FRP reinforcement and formwork. These projects pointed out the need for a competitive SIP formwork to be used in conjunction with FRP reinforcement. Two specimens with different FRP reinforcement and SIP formwork arrangements were tested. Full-scale deck slab specimens were tested by applying a simulated wheel design load to investigate the static response, ultimate capacity, and failure mechanism. The most economical FRP reinforcing system has been implemented in a superstructure replacement project in Greene County, Missouri.

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.

This paper implements a domain integral energy method for modelling crack growth in composite material shell structures using the finite element method. Volume integral expressions to evaluate the dynamic energy release rate in a through-thickness three-dimensional crack are derived. Using the domain integral, the energy release rate computation is implemented in the DYNA3D explicit non-linear dynamic finite element analysis program wherein crack propagation is modelled by releasing the constraints between initially constrained node pairs. The implementation enables the program to either determine the energy resistance response for the material (provided experimental data is available) or predict the rate of crack propagation in shell structures. The numerical implementation was verified by simulating mode I and mode III slow crack growth problems in semi-infinite transversely isotropic media, for which analytic solutions are available. Oscillations of energy following the release of nodal constraints as the crack propagates in discrete increments were suppressed using light mass proportional damping and a moving averaging scheme. Copyright © 2004 John Wiley & Sons, Ltd.

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.

Progressive tearing failure has been identified as an important damage mechanism in single-cell, thin-walled, rectangular pultruded composite material tubes subjected to transverse (bending) loads. This progressive failure occurs along the corners of the tube at the junction between the cell walls and propagates in a stable fashion as the transverse load is increased. This allows the tube to undergo large global flexural deformation as well as local cell wall deformation needed to develop membrane response before ultimate failure. The response enhances load-carrying capacity in the tube and provides energy absorption during the failure. A numerical method has been developed to model the crack propagation along the corners of the tube using an energy criterion. The energy release rate for the mixed-mode crack propagation corresponding to the progressive tearing failure has been determined for pultruded composite material tubes that were tested in a previously reported experimental study. Effects of different tube configurations, geometries, and end-supports on the energy absorption are reported. It was found that substantial energy can be dissipated by the progressive tearing failure of the tube if appropriate axial restraint is provided at the ends of the tube.

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.