UMaine composites center wins key patent

The University of Maine's AEWC Advanced Structures and Composites Center has been issued a patent for coming up with a method of prestressing glued-laminated timber beams to strengthen the wood for use in construction.  Habib Dagher, director of the Advanced Structures and Composites Center, holds a roll of the glass fiber reinforced polymer (GFRC) that is bonded to the tension side of a beam, increasing the beam's strength by 38%. Dagher and Associate Professor of civil engineering Mac Gray are the lead inventors on the patent.
Linda Coan O'Kresik
The University of Maine's AEWC Advanced Structures and Composites Center has been issued a patent for coming up with a method of prestressing glued-laminated timber beams to strengthen the wood for use in construction. Habib Dagher, director of the Advanced Structures and Composites Center, holds a roll of the glass fiber reinforced polymer (GFRC) that is bonded to the tension side of a beam, increasing the beam's strength by 38%. Dagher and Associate Professor of civil engineering Mac Gray are the lead inventors on the patent.
Posted Feb. 10, 2011, at 11:26 p.m.
Last modified Feb. 11, 2011, at 4:51 a.m.

ORONO, Maine — The University of Maine’s Advanced Structures and Composites Center has been issued a patent for technology that researchers there say is the first of its kind in the world.

After five years of research and development, a group of faculty members and students at the center were able to reinforce large timber beams — typically used in the construction of bridges and roofs — with a thin strip of material made of resin and fiberglass. The material, only about 5 inches wide and an eighth of an inch thick, is bonded to the bottom of a beam, increasing its strength by 38 percent, according to the inventors.

Among other things, the patent will give credit to the AEWC for inventing the method of reinforcing the beams.

Habib Dagher, director of the AEWC and a lead inventor of the technology, said it has the capability of “transforming” portions of the construction industry, as it will cut the costs of materials in half.

“Imagine when you go to build a bridge, instead of using four beams you only have to use two,” Dagher said. “By reinforcing the beam with this material, it becomes stronger and reduces the amount of materials needed to support a structure. The implications for construction are many.”

Dagher said researchers from across the country and throughout the world have been working for years to perfect the technology, known as Prestressed FRP-Glulam Girders. He said the technology has many applications — including in the building of houses, but mainly in the construction of bridges.

As a result, the Maine Department of Transportation and the Federal Highway Administration were major financers of the project. The DOT was expected to be on hand Thursday for a demonstration of the technology.

When asked how much the research and development cost, Dagher did not have an exact figure, but he said that with all the students and faculty involved in the project and the amount of materials used during testing, the amount was considerable and likely cost hundreds of thousands of dollars or more.

“The cost of the research, though, will transfer into significant cost-savings in the construction industry,” he said.

At a demonstration for the news media on Thursday, Dagher and another lead inventor, Mac Gray, an associate professor of civil engineering at UMaine, explained how the technology works. Beams that are 12 inches wide by 22 feet long are first bonded with a strip of the resin and fiberglass material, which Dagher likened to a rubber band because it is stretched to span the length of the beam. This material is twice the strength of steel, Dagher said. Next, after bonding is complete, hydraulic jacks prestress the beam by pushing upward.

Researchers found that when the beam has a slight upward bow — reinforced by the resin and fiberglass material — it is capable of carrying nearly twice as much weight because the prestressed beam counteracts the natural downward stress caused by any weight on the structure.

Gray said the AEWC applied for the patent in June 2009 and in early January of this year finally received it.

In addition to the DOT’s role in research and development, Dagher said a number of other industry-related companies are expressing an interest in the technology’s applications.

“What’s exciting about all of this is the fact that we finally received this patent and the University of Maine won the race in inventing this technology,” Dagher said.

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