Hussam Mahmoud, an assistant professor of civil and environmental engineering at Colorado State University (CSU), is leading a team that’s devising innovative repairs for steel structures in canals and rivers – some dating back to the 1920s – that are showing their age due to corrosion, fatiguing and cracking.
Specifically, the engineers are analyzing how cracks behave in various conditions, and how and when they lead to structural failure. They are almost done with the first phase of a project, supported by the U.S. Army Corps of Engineers, to provide new ways to repair such structures in heavily trafficked waterways, including the Mississippi River. In this project, the researchers are testing the efficacy of carbon fiber reinforced polymer (CFRP) sheets adhered to existing cracks in steel. Some of their results have already been implemented in the field by the Army Corps, according to Mahmoud.
“The presence of a crack is not a big deal, until that crack propagates, and then it becomes a big deal – to the point where the structure could collapse,” Mahmoud said.
For an experiment running in early November, the researchers are using a 10-foot vertical actuator to bear about 120,000 pounds of force on a cracked plate, while water flows around it – simulating conditions in rivers and waterways.
According to CSU, another researcher with Mahmoud’s group, graduate student Stephanie Pilkington, is observing the experiment to gain insight into how navigation structure failures affect whole communities across the U.S.
Pilkington is how communities recover from natural or manmade disasters like floods or fires. In this case, the potential complete shutdown of an economically important waterway could have devastating effects on the people near it.
In partnership with the CSU NIST Center for Risk-Based Community Resilience, Pilkington is building a resilience model that could be applied to many communities, and that takes into account the interconnected threads of civil structures, economic and sociological impacts. The carbon fiber retrofits Mahmoud’s group is testing could play a key role in bolstering a community’s resilience.
“If a retrofit can withstand a disaster, you can still have that transportation sector, which ties into your economic survival,” she said.