CORVALLIS - The Oregon Department of Transportation has awarded civil engineering researchers at Oregon State University nearly $1.6 million to help the state more quickly analyze the severity of cracks that have been identified in more than 500 of its bridges.
The OSU researchers will develop modeling tools and data banks that can be used to forecast how the cracked bridges will perform over time. This data will help ODOT officials assess the remaining capacity and predict the remaining life of cracked bridges, and may also identify bridges that might not be affected by the cracks.
The cracks, the first of which were detected just two years ago during routine ODOT inspections, affect bridges on Oregon's interstate and state highways, and could potentially affect even more yet-to-be-identified bridges on county and city roadways.
"This is a very significant problem," said Christopher Higgins, OSU assistant professor of civil engineering at OSU and principal investigator on the research project. "And it's complicated by the fact that the cracks were discovered only recently. ODOT is working very hard to address the problem, and we're very pleased to be helping to find a solution quickly."
Just last year, OSU built a state-of-the-art "strong floor" structural testing laboratory on campus as part of its drive to establish its College of Engineering as one of the top 25 in the nation. The new laboratory enables engineering researchers to carry out full-scale experimental tests and data analysis on structural elements, some of which are four-foot thick concrete bridge components.
"Without our new strong floor laboratory, ODOT would have needed to go out of state to conduct this research," said Higgins, an international leader in this research area.
The ODOT grant, and use of the strong floor, will allow Higgins, a team of five graduate students and fellow OSU faculty members Solomon Yim and Tom Miller to test bridge components to the failure point by applying forces, or the weight from vehicles moving across the bridge.
"There is almost no data available to determine how bridges actually fail under moving loads," said Higgins, who joined the OSU engineering faculty two years ago. "This grant is allowing us the unique opportunity to address these kinds of issues. And in the process we're providing research that is critical to Oregon and Oregonians."
The narrow cracks, called shear cracks, mainly affect reinforced concrete bridges built between 1947 and 1962, and appear to be the result of age and increased traffic loads.
"Many of Oregon's bridges built during this time were not designed for today's weights, volumes and traffic speeds," said Jay Remy of ODOT's public affairs office. "And insufficient investment over many years has prevented the bridges from being replaced on schedule."
The state is monitoring the cracks closely and taking measures as needed. ODOT has already posted weight restrictions on a number of bridges and closed, repaired, and reopened one bridge near John Day. The agency also ordered a shoring project on Ford's Bridge on I-5, which temporarily routed traffic through Roseburg.
Although the postings don't affect smaller vehicles like cars and pickup trucks that make up the bulk of highway traffic, detouring larger trucks around posted bridges can have an impact on the economy, which is why the OSU research project is on the fast track.
"The posted weight restrictions do not affect cars," Remy said. "But because trucks deliver needed goods to every community in Oregon, weight restrictions can affect Oregon's economy through higher shipping costs, delays, and significant local impacts."