University of Utah civil and environmental engineering professor Chris Pantelides, with his team of researchers, has developed a new composites-intensive process to fix bridge columns in as little as a few days. According to the university, Pantelides’ process is quicker and more cost-effective than traditional repair methods, which often take weeks. Although the process was specifically designed for repair, the university says it could also be used to retrofit bridges to make them more earthquake-safe.
The process involves creating concrete donut shapes known as “repairs,” which are lined with carbon fiber reinforced polymer (CFRP) composites built around the bottom and top of each column. The university says the team used CFRP because it is stronger than concrete by itself and steel.
“With this design and process, it is much easier and faster for engineers and crews to rebuild a city ravaged by an earthquake so that critical roadways remain open for emergency vehicles,” Pantelides says.
First, a number of steel rebars with heads are drilled into the foundation around the column and secured with an epoxy. Then two halves of a circular shell, made of millimeter-thick CFRP, are placed around the column and rebar and spliced together. Concrete is then poured around the column and over the rebar with the composite fiber acting as a mold. According to Pantelides, the result is a repaired column with approximately the same structural integrity as the original column.
“The circular shape gives you the best strength for the amount of material you are using. The stresses are distributed equally all around the periphery,” Pantelides says. “With this method, if there are future earthquakes or aftershocks the bridge will survive and damage will happen adjacent to the donut. This gives the bridge a second life.”
The team notes that the repair process is not limited to bridges. It can also be used on damaged columns around buildings. Pantelides and his team have filed patents on the process, and he says it can be utilized by construction companies on earthquake-damaged areas immediately.
For more information, check out the team’s technical paper in the latest American Concrete Institute Structural Journal.