The tests, which were performed on enormous shake tables, took place on April 24, put a 70-ton, two-span, 70-ft.-long bridge through simulations of a 7.5-magnitude earthquake.
Good news: A series of tests at the Earthquake Engineering Laboratory at the University of Nevada, Reno, has determined that accelerated bridge construction methods are safe and ready to be used on job sites.
The tests, which were performed on enormous shake tables, took place on April 24, put a 70-ton, two-span, 70-ft.-long bridge through simulations of a 7.5-magnitude earthquake. Six different types of bridge connections, built into one bridge, were tested; previously each connection had undergone its own separate test at the University, Nevada Today reported.
“The individual connection tests had given us very good results for each connection,” said Dr. Saiid Saiidi, director of the Center for Advanced Technology in Bridges and Infrastructure, professor of civil and environmental engineering at the University of Nevada and the project's principal investigator. “And for the first time, our study combined these connections in a single bridge which endured realistically strong earthquakes. We knew that going into this that our individual positive tests did not inherently mean that all of the connections would work together, making this a necessary test.”
The tests had two key outcomes that Saiidi's team looked for:
- Four of the six connections were built to remain undamaged during large-scale earthquakes, and
- Two connections were meant to take on a certain amount of damage. By breaking they absorbed some of the forces exerted on the structure from the earthquake.
The results looked good.
“Along with avoiding collapse, the outcome of our study showed that all of the six connections performed as expected,” said Saiidi. “It will be a few months before we can evaluate data from the 280 sensors that we had in the bridge to get more insight about the connections … but we are now confident to recommend these connections for application in real bridges.”
The Bigger Picture
The study, which was part of the University of Transportation Center on Accelerated Bridge Construction project (ABC-UTC), was funded by the U.S. DOT, Nevada Today reported.
“There are many aspects of bridge construction and safety that ABC-UTC is researching, such as ease of construction and durability of joints,” said Saiidi. “The University of Nevada, Reno is part of the seismic performance portion of ABC-UTC Seismic, which is the most critical aspect when it comes to bridge connections.”
ABC-UTC Seismic's key goal is to develop a series of precast bridge components and systems that are earthquake-resistant, as well as translate their research data into design guidelines to help boost the usage of ABC construction methods in areas where moderate to high seismic activity occurs, Nevada Today reported.