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Bridge Product Gateway IntroductionFRP composite marine piling was developed in the early 1990s to provide a solution for deteriorated piers and waterfront structures subjected to the harsh marine operating environment. FRP composites represent an alternative construction material without many of the performance disadvantages of conventional materials such as rot, rust, and spall. The population growth of marine borers, strict environmental laws that limit the use of toxic treatments for wood, and prohibitions on traditional maintenance practices (lead-based primers, sandblasting, and solvent-based paints have resulted in higher maintenance and replacement costs for traditional materials. Composite materials offer long-term and low-maintenance solutions. The use of composite piling in aggressive environments has been proven to be more economical when life-cycle costs are considered. Private industry development programs and government-sponsored research have worked towards selecting and optimizing composite materials and tested products to meet the performance needs of the owner in waterfront facilities. The U.S. Army Corps of Engineers, Champaign, IL, and the Naval Facilities Engineering Service Center, Port Hueneme, CA, in conjunction with the composites industry, conducted development programs to evaluate products that could retrofit and replace current products used in waterfront structures. The products evaluated in these programs included both FRP composite piling and FRP reinforced concrete piles. Since 1990, FRP composites have been used for marine retaining walls in applications such as beaches, causeways, docks, harbors, lakes, residential developments, rivers and streams. Composite products have been installed as fender and structural piles for piers, docks, and wharves. Design of composite piles varies depending on the type of pile selected and performance requirements. Available types of composite piling products:
Applications:
FRP composite marine piles provide engineered materials with defined, uniform and predictable strength and stiffness properties, whereas wood can have large variations of properties due to cracking, knots, splintering or other damage. FRP composite piles are designed for specific applications. In general, composite materials provide the owner with many performance benefits including:
FRP composite marine piles have seen service since the early 1990’s and have become widely accepted as fender piles by many Port Authorities, U.S. Navy, U.S. Army Corp of Engineers, and numerous State DOTs. Unique to the bridge engineer is the use of composite piles for bridge pier protection systems. This application takes advantage of the engineered properties for individual fender piles and timbers and organizes them in the form of guide-walls or dolphin clusters to protect bridge piers from collision damage by marine vessels or debris from nature’s most violent storms. The composite bridge fender systems are often constructed in a similar fashion to traditional timber bridge fender systems. Composite piles are driven in either a plumb and batter configuration attached to which, composite timbers run in horizontal rows. This creates a flared fender section, which will guide vessels into the channel and away from the bridge piers. The highly ductile material properties of composite piles & timbers enable the absorption of fifteen times more energy than a similar cross section of timber. Composite piles & timbers offer a smooth, abrasion and UV resistant outer skin with a low co-efficient of friction, this enhances the ability of vessels to slide along the fender system after impact. Several universities, government and state agencies have evaluated composites for bridge structures. A program involving the Federal Highway Administration, Virginia Department of Transportation, Virginia Transportation Research Council, and Virginia Tech are assessing several piling products for driveability, capacity, and durability. Manufacturing The pultrusion process is used to manufacture the composite sheet pile. Materials such as glass reinforcements and a premium-grade polyester resin containing a UV inhibitor are used to give the product corrosion resistance and required strength. Color and other characteristics can be designed into the profile by changes in the resin mixture and reinforcement materials. However, FRP composite marine piles and timbers are manufactured in a two-step process. First, the FRP rebar, upon which the product relies for its strength is pultruded. Second, the FRP rebars are positioned in a mold, and combined with chopped glass fibers that reinforce a polyethylene-based matrix through continuous extrusion process. The tough outer skin is applied through co-extrusion. Installation FRP composite sheet piles are lightweight for ease of installation and can be installed using standard piling installation equipment such as impact hammer, vibrating hammer and water-jet equipment. All field cut and drilled edges, holes and abrasions are sealed with resin. The sealing of the edges prevents fraying at the field cut edges. Upon completion of the composite sheet pile installation, a cap is used to close off the top of the pile and also as a waler to increase the overall strength of the total system. The cap product is a pultruded profile designed to fit on top of the respective product. FRP composite marine piles and timbers have a similar density to wooden products of a similar cross-section. Standard installation methods are used to lift and handle, drive, vibrate or jet, and to cut and drill the products. Carbide tip tooling is required for cutting & drilling. The exposed ends of composite piles and timbers require no special sealing. Traditional fasteners are used to connect composite piles and timbers to each other and to the dock. Marine Piling & Timber Suppliers
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