FRP Pilings Are Making A Big Splash In The Nation’s Waterways With High-Energy Absorption, Zero Maintenance Fender Protection
It’s no fish story that FRP pilings are becoming entrenched as the go-to material for fender protection in the nation’s waterways. The reasons are numerous. Unlike rigid concrete and steel systems, FRP is maintenance free and can deflect, dissipate energy and recover without damage to ships or fenders. The green material also supports the environment. In Puget Sound, scientists are studying the impact of creosote-treated wood pilings on dwindling herring and shellfish populations. FiberPILE resists corrosion and damage from intrusive marine life without leaching harmful chemicals into the water.
If you take a look at the marketplace for marine piling products, you’ll see everything from wood and plastic to steel and concrete. Wood has certainly been around the longest, but the trend among environmental regulators to prohibit its use in marine environments makes it less and less desirable. Steel and concrete have corrosion issues and are costly to install. Larger vessels are driving the need for pilings that can protect ships, docks, canal entrances and the bases of bridges from damage while effectively absorbing large amounts of kinetic energy. Bearing piles for wharves, piers, power transmission towers and bridges must withstand substantial axial loads to effectively support an overhead structure. In contrast, freestanding piles installed to protect bridge piers and other waterfront structures must resist lateral loads. FiberPILE’s performance properties make the product suited for each of these applications. Check out our next news item to see a current case study.
What Is FiberPILE?
FRP pilings are fence posts in a fender system that supports wales or guard rails. FiberPILE products are large diameter FRP piles used in fenders with higher impact energy requirements. The flexibility of FRP materials allow FiberPILE products to be engineered to any diameter or thickness required. Standard diameters range from 18-in. to 48-in. and can be fabricated in continuous lengths up to 110 ft. The product has a design modulus of 5.7 msi and an ultimate strength of 55 ksi, mirroring the high-strength properties of steel. Piles can be installed with conventional equipment such as impact and vibratory hammers. The design flexibility allows FiberPILEs to attain a wide range of moment capacity and stiffness to meet design requirements. With a high strength-to-weight ratio, corrosion resistance to salt water and chemicals, an impervious nature to marine borers, and eco-friendly footprint, FRP piles are becoming the material of choice.
How Is FiberPILE Made?
The high-strength and tailored design properties result from a combination of engineered materials and manufacturing techniques. A unique closed molding vacuum infusion method provides a high fiber-to-resin ratio that makes FiberPILE stronger and lighter than other products on the market. This allows piles to be fabricated to any diameter and wall thickness with minimal fixed costs. Unlike rigid products which cause a vessel or structure to absorb impact energy through damage, FRP piles are designed to deflect and recover by dissipating energy without damage to ships or structures. A specialized fiber architecture makes FiberPILE as strong as steel. Since FRP composites are orthotropic materials, properties can be tailored along each axis and in each direction. Fiber orientation is important because placing the majority of fiber in the axial direction maximizes bending properties while fibers in the +/-45 degree direction optimize torsional resistance and pin bearing. Material property testing of laminates evaluates basic strength and stiffness. Effects of temperature and moisture are included. Structural testing includes bolt bearing and crushing. FiberPILES are subjected to full scale testing in a four-point bending configuration to assess bending moment capacity and stiffness. FiberPILES have been tested in flexure to meet ASTM D6109.
How Is FiberPILE Installed?
To drive FiberPILE products, a contractor can use standard equipment like a vibratory or impact hammer. If a vibratory hammer is used, the contractor must attach the caisson clamp directly to the pile. The clamping surface should be level to minimize damage at the point of contact. Hammer size depends on site-specific soil conditions along with the pile diameter and weight. Impact hammers work better for larger piles in harder soils. A steel head is used on the top of each pile as an interface to distribute the hammer’s impact forces. Hollow construction, light weight and low driving friction make FiberPILE products attractive to contractors. Piles can be spliced when there is low overhead clearance under bridges or for lengths too long to transport. The product is easy to field cut with conventional concrete cutting equipment that uses a diamond or abrasive grit blade. A carbide tipped drill bit makes piercing FiberPILES for waler connections simple and quick. Acoustic testing has demonstrated FiberPILE’s low peak sound pressure levels. Results showed that injury to fish from composite pile installation with an ICE 28D or similar-sized vibratory hammer is not possible. Recorded maximum peak sound pressure levels tested well below the FWGP threshold. Click here to see a video of a FiberPILE installation.