International Concrete Abstracts Portal

SP-215 The field application of fiber-reinforced polymer (FRP) composite materials as reinforcement for concrete structures has been growing rapidly in recent years, mostly with interest in alternatives to steel reinforcing bars and for strengthening concrete structures. FRP products provide options and benefits not available using traditional materials. As a result of the extensive use of FRP as internal and external reinforcement for new structures and strengthening concrete structures, respectively, ACI Committee 440 organized three technical sessions on “Field Application of FRP Reinforcement—Case Studies” with a total of 21 papers presented at the ACI Fall 2003 Convention in Boston, Mass. All papers deal with case studies and demonstration projects to provide clear evidence of the practicality, credibility, and maturity attained by this technology. This volume includes the papers presented during the Fall 2003 Convention, plus five additional papers that augment the range of field applications and case studies. The goal of this document is to help practitioners implement FRP technology, while providing testimony that design and construction with FRP material systems is rapidly moving from emerging to mainstream technology.

Innovative pile foundations consisting of concrete-filled circular fibrereinforced polymer (FRP) tubes (CFFT) have increasingly been used for a variety of applications, mainly in marine environments. This paper presents a different application of CFFT in two bridges in the State of Virginia, the Route 40 and Route 351 bridges. Some of the piles in these bridges consisted of CFFT, which were projected above the ground level to function as piers for support of the superstructures of the bridges. The paper presents the results of full-scale field test programs carried out at the two bridge sites, before construction of the bridges, in order to compare the structural and geotechnical performance of the new CFFT composite piles to conventional prestressed concrete piles. Details of the construction and connection between the CFFT composite pile and RC cap beam are also presented. The Route 40 Bridge has been in service since 2000 and to date, no indications of unsatisfactory performance have been reported. The new Route 351 Bridge is expected to be finished and open for traffic in May 2003.

A new connector system and a new method for the construction of partially precast concrete sandwich panels are described. The new connectors are constructed using glass fiber reinforced polymer and are used to tie two precast concrete layers together through a layer of rigid extruded polystyrene insulation. In contrast to existing connector systems that incorporate steel lattice girders, the new system effectively eliminates thermal bridges and undesirable forced compatibility strains in the concrete layers. In addition to providing energy savings for the building owner, the new system and method can provide cost savings for the wall fabricator.

The corrosion resistance of fiber-reinforced polymers, in addition to their high-strength and lightweight, makes them a promising alternative to traditional steel reinforcement in bridge decks. In cooperation with the Cuyahoga County (Ohio) Engineering Department, a health monitoring system is being implemented on a 3500 square foot replacement concrete bridge deck reinforced completely with glass FRP reinforcing bars. The monitoring system incorporates dynamic and environmental data sampling, occurring on a quarterly basis. Instrumentation includes strain gages, temperature probes, and displacement transducers. This bridge deck represents one of the first utilizations of FRP reinforcing bars on an Ohio bridge. The investigation, at its conclusion, will serve as a valuable record of composite behavior and may foster broader use in area bridge decks.

Substitution of conventional steel reinforcing rebars with Glass Fiber Reinforced Polymer (GFRP) rebars in Continuously Reinforced Concrete Pavement (CRCP) gives solutions to the problems caused by corrosion of reinforcement. Concrete volume change, due to shrinkage and temperature variations is known to cause crack development in CRCP. In this study, the stress levels in concrete and GFRP rebars and the crack widths at various crack spacings are predicted using numerical methods. The results reveal that using GFRP rebars as reinforcement in CRCP reduces the tensile stress in concrete. The bond-slip between concrete and reinforcement and the friction from the pavement's subbase have important effects on the development of the reinforcement's stresses and the crack widths. The design of a GFRP-reinforced CRCP to be constructed during this year is proposed. The behavior of the CRCP due to concrete shrinkage and temperature variation is predicted. The stress levels in the GFRP reinforcement, the crack width and the crack spacing of the proposed pavement are shown to be within the design requirements.