The 273-mile-long Illinois River is a primary tributary of the Mississippi River and part of an important waterway connecting the Great Lakes to the Mississippi River. Barges transporting goods ranging from grain to oil traverse the waterway thanks in large part to several locks and dams managed by the U.S. Army Corps of Engineers (USACE). In August, GFRP wicket gates were installed on one of those navigational structures – the Peoria Lock & Dam on the Illinois River at Creve Coeur, Ill.
“Maintaining waterway navigation is a big part of what the
Corps of Engineers does for our nation,” says Rich Lampo, materials engineer
with the U.S. Army Corps of Engineers, Engineer Research & Development
Center (ERDC) in Champaign, Ill. “But a lot of navigational structures have far
exceeded their original design life. Our mission is to investigate the use of
fiber-reinforced polymer materials to help maintain and replace aging
That mission is critical considering that 95 percent of the dams managed by the USACE are more than 30 years old and 52 percent have reached or exceeded the 50-year service lives for which they were designed. According to the USACE website, it would cost $24 billion to fix all the dams that need repairs.
In 2011, the ERDC began partnering with West Virginia University (WVU) to investigate low-maintenance, corrosion-resistant composite components for locks and dams that lower life cycle costs. They began by designing, testing and implementing recess filler panels and wicket gates – low-risk applications that could demonstrate the potential use of composite materials in navigation structures. Recess filler panels are used in locks with emergency lift gates to fill in the area in the lock wall when the emergency gate is lowered. Without the panels, vessels passing through the lock could hit and damage exposed corners of the wall. Wicket gates help maintain a navigational pool in the river. The gates rest on the bottom of the river and are raised when the water gets too low.
Hota V. GangaRao, a civil and environmental engineering professor at WVU and director of the Constructed Facilities Center, is one of the investigators on the project. GangaRao began work on composites in 1987 and teamed with the USACE on three projects related to roadways and bridges in the 1990s. Work on those projects served as a building block for the lock and dam structures, which are typically made from wood, concrete or steel. “We are the first ones to implement GFRP-based products for navigational structures in the United States,” says GangaRao.
He cites several reasons why GFRP is ideal for lock and dam components. First, the material is corrosion-resistant, which lowers maintenance costs. “The more maintenance you have, the more delays in the navigational system,” says GangaRao. Locks shut down during maintenance, which can cause thousands of dollars in lost productivity.
In addition, GangaRao felt that WVU could design and install some navigational structures at a lower initial cost than existing materials. Some of the structures require very large timber, and GangaRao says it’s much more difficult to obtain quality wood in those sizes than it was 30 to 50 years ago. “We hope that using GFRP can reduce both initial and life cycle costs,” he says.
WVU began by investigating options for recess filler panels, which are traditionally made of welded steel I-beams, angles and plates. This makes them heavy to lift and susceptible to corrosion. University researchers developed and tested four different FRP recess panel designs, then partnered with Creative Pultrusions in Alum Bank, Pa., to fabricate the one that performed best – a hexagonal FRP superdeck system.
The company pultruded three prototype recess filler panels that are 10 feet long, 12 inches wide and 8 inches thick and include a top surface coating from Rhino Linings®. The panels use a vinyl ester resin and more than 30 layers of fiberglass fabric, including 0/90° and ±45° fabrics. “The fiber orientation is extremely complicated,” says GangaRao. “We are making sure the panels have enough shear capacity as well as enough bonding strength.” The panels have been delivered to the Willow Island Locks near Newport, Ohio, and should be installed this spring.
Next, WVU worked with the USACE to design GFRP wicket gates measuring 16 feet long, 4 feet wide and 8 inches thick. The composite design is corrosion-resistant and provides equal or better mechanical properties than a wooden wicket gate. It’s also compatible with the original hardware, which makes it easier to replace and operate the gate. Composite Advantage in Dayton, Ohio, fabricated the gates using vacuum-assisted resin transfer molding (VARTM). The gates underwent various bending tests at WVU, then the engineers made some design modifications. For example, they added an ultra-high molecular weight polyethylene layer on the face of the wicket gates to help prevent abrasion and ice damage.
The gates, installed last August on the Illinois River, are working well so far. They will be pulled from the river and inspected this summer. Equally important to their performance is the anticipated cost savings for the two locations on the Illinois River using wooden wicket gates. “Because of the extended lifetime of the composite gate versus a wooden gate, as all of the wooden wicket gates are changed over, we calculate a savings of almost $19 million over a 50-year lifetime,” says Lampo. “We’re hoping that will kick start interest in the use of composites for other more demanding lock and gate structures.”
With approximately 87,000 dams listed in the National Inventory of Dams, which is maintained and published by the USACE in conjunction with the Association of State Dam Safety Officials, there certainly is a lot of potential for FRP materials. The floodgates are open for composite solutions.
Posted with permission from ACMA and Composites Manufacturing magazine.
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