When one considers the construction market, there’s a wide variety of product applications that utilise fibre reinforced plastics (FRP). These range from residential and commercial buildings with grandly unique architectural geometries, to emergency shelters and modular housing, plus fencing, lumber, roofing, window/door frames, and on to corrosion-resistant industrial structures such as tanks, pipes, flue gas scrubbers and more.
Lastly come roads, highways, rail systems, dams, ports and waterways, and electric utility structures that support every country’s infrastructure.
A critical factor that all types of FRP construction projects have in common is that they must be framed correctly, literally, to meet structural performance and safety requirements. The same holds true for framing construction codes, based on proven in-field performance, to help guide civil and structural engineers, builders, designers and architects in materials selection that treats FRP on par with, or complementary to, conventional materials.
Sources for this article are pioneering change in the use of FRP in construction applications and working with relevant construction code bodies. Each offers his frame of reference for the multilayered definition of true innovation in terms of recent, specific infrastructure projects. By their accounts, the meaning of innovation bridges thinking and acting to bring change to the largely conservative construction industry, which is no easy task considering the historic public safety liabilities and today’s uncertain, restrictive economy.
Bearing the standard
As reported by Reinforced Plastics in September 2011, the Pultrusion Industry Council (PIC) of the American Composites Manufacturers Association (ACMA) is working to convert its industry guidelines into an American Standards Institute (ANSI) Code of Standard Practice for Fabrication and Installation of Pultruded FRP Structures.
ACMA is also working with the American Society of Civil Engineers (ASCE) on the Prestandard for Load and Resistance Factor Design (LRFD) of Pultruded Fibre Reinforced Polymer Composite Structures.
John Busel, Director of ACMA’s Composites Growth Initiative, comments on the status and importance of adopting such construction standards.
Reinforced Plastics: What’s innovative about the effort to include composites in construction codes, and what’s the timeline for adoption of these particular codes?
Busel: The creation of the LRFD Prestandard under ASCE’s guidance began in 2007 as part of a visionary, long-range initiative by ACMA and its member companies to increase the use of composites in construction and affiliated industries. The standard will allow structural composites to be more readily accepted by structural engineers, mainly in vertically-built structures, but with application to horizontal structures as well, such as bridge decks.
The effort toward the ANSI standard by PIC is very important because it conveys the message to engineers that the composites industry has practiced and proven rules and procedures for its materials and manufacturing. This encourages a level of confidence for engineers, giving them a way to count on the composites industry and composite materials/manufacturing in terms of repeatability and credibility when FRP is specified in construction applications.
In terms of code adoption timeline, we have balloted the PIC/ANSI standard and hope for approval by end of first quarter. The LRFD Prestandard effort now requires validation by each chapter within the starting PIC initiative, and is being directed by the ASCE Fibre Composites and Polymers Committee, of which I am a member. I hope all the chapters can be resolved by the end of 2012 to become a formal ASCE standard.
Global need
Busel knows infrastructure and FRP applications, and not just in the US. In 1996, he was invited by the US Federal Highway Administration (FHWA) as one of 13 individuals to tour 30 FRP-enhanced bridges in five different countries (Scotland, England, Switzerland, Germany, and Japan). The purpose of the tour was to evaluate performance and durability of the bridges, assess the state of selection, design, manufacturing, testing and specification of composites in these structures and to interview owners about installation, cost and structural performance.
Among his own “lessons learned” from the tour, Busel concluded that, globally, there is a need for:
- proven data from long-term bridge applications;
- written design guidelines;
- written material specifications and standards;
- civil engineering firms who champion FRP; and
- the forming of close relationships by such firms with composites manufacturers and structure owners.
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The ACMA / ANSI standards are not the first to address FRP in composites, but ultimately remain on a relatively short list. Since 2008, Committee 440 of the American Concrete Institute (ACI), focused on Fibre-Reinforced Polymer Reinforcement, has published six specifications involving fibre reinforced polymer rebar for concrete reinforcement. This in addition to at least 15 design, manufacturing and testing guides and reports involving FRP in concrete and dating back to 1992. ACMA’s Busel comments that “while ACI documents specifically deal with reinforced concrete, the number of design guidelines and standards/specifications to come out of Committee 440 have certainly helped ACMA’s efforts with the ASCE. The fact that other standards exist on FRP composites will help create future standards.” Four structural test method standards for composites in civil structures have been formulated by subcommittee D30.05 of the American Society for Testing and Materials (ASTM). These test methods cover:
A proposed new ASTM standard, WK27200, addresses test methods for alkali resistance of FRP matrix composite bars used in concrete construction. From the American Association of State Highway and Transportation Officials (AASHTO), key documents offering guidance in using FRP in infrastructure construction include LRFD Bridge Design Guide Specifications for GFRP-Reinforced Concrete Bridge Decks and Traffic Railings (2009) and the Guide Specifications for Design of FRP Pedestrian Bridges (2008). |
For Busel, these conclusions still hold true. He observes that:
“Fifteen years ago, FRP composites were new and fascinating for civil engineers. The composites industry as a whole has matured greatly over that time, which is one reason we need specifications and standards in place so civil engineers can more readily specify composites. We are not just limited to R&D projects any more; commercial ventures have become the norm. In North America today, there are some 400 new infrastructure installations utilising FRP and greater than 5000 installations where structural strengthening FRP systems are part of repair/rehabilitation of reinforced concrete. We want to keep that list growing because composites can save engineers many problems in the future through corrosion resistance and durability properties.” ♦
This article is taken from the feature Infrastructure innovations, which was published in the May/June 2012 issue of Reinforced Plastics magazine.
Parts 2 and 3 of this feature are also available on the Reinforced Plastics website (see links in Related Stories section.)
