Structures
Simple Steps on How to Specify FRP Composites for your Next Job By Dustin Troutman, Director of Marketing and Product Development, Creative Composites Group
Fiber Reinforced Polymer (FRP) composites have emerged as a top contender when it comes to construction material choices for America’s infrastructure. “FRP has been used in construction projects for more than 30 years, but over the last decade the number, size and complexity of projects has grown rapidly,” says Gregg Blaszak, president of Coastline Composites. “Awareness has also increased among engineers and contractors about the ways FRP’s unique attributes can contribute to a project.” Coastline Composites is a technical marketing and consulting firm with a focus on developing applications for FRP in the heavy and civil construction industry. The firm partners with leading FRP suppliers like Creative Composites Group (CCG) to offer cost-effective solutions to engineers, contractors, and asset owners. CCG serves major infrastructure markets from rail and bridge to utility and waterfront with design-build and structural fabrication expertise. FRP’s growing popularity is also being boosted by the Bipartisan Infrastructure Bill, which, in 2021, introduced innovative materials like FRP into mainstream procurement processes for the first time. In a May 2023 update, the bill earmarked $40 billion for bridges alone and $66 billion for passenger and freight rail. According to Blaszak, pedestrian bridges and passenger rail are two markets that have proved to be “the right fit for FRP.” “Lightweight is one of the biggest reasons FRP is selected for a project,” says Blaszak. “For example, FRP has become the material of choice for the rehabilitation and repair of historic bridges due to their inherent weight restrictions. Cantilevering an FRP sidewalk off of an existing vehicle bridge accommodates bicycles and pedestrians without putting large dead loads on the bridge. It is also less costly and less disruptive than other options. And, in highly congested urban areas with limited access to stage construction equipment, FRP helps
contractors accelerate installation. Time is money in construction and FRP saves contractors a lot of time on their projects”. Aside from its lightweight and quick installation, FRP is not susceptible to deicing chemicals making it well-suited for bridge and commuter rail structures in cold-weather states. “Traditional materials just don’t last in these types of applications,” Blaszak says. “Most engineers interested in specifying FRP understand the initial price point for composite material may be a little higher, but lightweight, rapid erection and corrosion resistance often lead to lower overall project costs.” CCG’s proficiency in prefabrication of very large FRP panels offers another advantage. The ability to construct composite components beforehand means the supplier can coordinate design and construction specifications upfront during the fabrication phase of a project instead of at the job site—factors that also contribute to faster installation and reduced costs. Specifying FRP for a bridge deck or rail platform can be challenging for several reasons. According to Blaszak most engineers are not experts when it comes to the design and detailing of FRP structures. Standard DOT specifications for large FRP structures don’t yet exist. Each project is usually handled using special provisions. Industry guides and specifications offer limited help. The most useful is the American Association of State Highway and Transportation Officials (AASHTO) Guide Specification for the Design of FRP Pedestrian Bridges. First published in 2008, the specification is being updated to reflect current best practices. The American Society of Civil Engineers also recently approved a standard for Load and Resistance Factor Design (LRFD) of Pultruded FRP Structures. “Composite materials are different from traditional construction materials,” says John Busel, vice president, Composites Growth Initiative, for the American Composites Manufacturers Association (ACMA). “Design guidelines are intended to help engineers focus on the important attributes of composites and construction techniques
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csengineermag.com
October 2023
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