Research that could change the bridge construction industry has led to South Dakota State University graduate student Ted Sjurseth becoming the University Transportation Center Outstanding Student of the Year for the Mountain-Plains Consortium. Eight universities stretching from Utah to North Dakota are part of the MPC.
Sjurseth, a 4.0 graduate student in civil engineering from Boyd, Minnesota, is the first SDSU student to receive the honor since 2014. He received the award in a virtual ceremony Jan. 6 coordinated by the American Road and Transportation Builders Association.
Sjurseth is doing research the use of bridge couplers in high-seismic regions under the guidance of assistant professor Mostafa Tazarv of the Department of Civil and Environmental Engineering. The project focuses on testing seven different types of couplers in seven precast concrete columns in the Jerome J. Lohrs Structures Laboratory’s large capacity hydraulic actuator.
The couplers, known as mechanical bar splices, connect sections of rebar within a concrete column. While the couplers can be used in other sections of a bridge column, bridge design codes do not allow the use of the coupler in high-seismic regions at the connection point of the bridge column and footer, Sjurseth explained. There is no practical value to using the bridge couplers at other points if they cannot also be used at the column-footer connection.
Faster, lower cost construction
Using couplers in bridge columns could speed the pace of bridge construction because more work could be done at a precast construction plant rather than on-site. Also, higher quality control could be achieved at the precast plant, said Sjurseth, who earned his bachelor’s degree in civil engineering in 2019 and carried a 3.91 GPA.
One main reason couplers are not used now is because of the lack of research to ensure their resistance to failure, Sjurseth explained.
“Test data regarding the performance of mechanically spliced bridge columns is scarce and the available data is for columns with different geometries, confinement levels and testing procedures. To better understand the seismic performance of mechanically spliced bridge columns, we are testing large-scale precast columns spliced with different bar couplers.
“Establishing a comprehensive precast column experimental database will allow us to verify or further modify the current design methods and might provide a justification to relax current coupler ban for bridge columns.”
Testing began in January
Sjurseth already built and tested a cast-in-place column to provide a comparison standard for the precast columns being built by Gage Brothers Concrete in Sioux Falls.
The half-scale octagonal columns are 9-feet tall with a 24-inch diameter. They will be tested to failure in the lab by mechanically pushing them back and forth with an increasing displacement load to simulate an earthquake, Sjurseth said. Testing one column at a time will begin the first week of January and wrap up by early March.
Results will be compiled and then forwarded to the federal highway group that sets design standards for bridges and could become evidence for changing the code.
Sjurseth, who will complete his master’s program in May 2021, joined Tazarv in this research because “it has huge implications around the world. The technology could be used anywhere there are earthquakes. California is one of the biggest regions, but also New York, South Carolina, spots in Missouri, areas where they are fracking now, Japan and elsewhere.”
Six industry partners from the U.S. and abroad are collaborating in this research project.
Impact on bridge, precast industry
Tazarv, coordinator of the Lohr Structures Lab and an SDSU faculty member since 2015, called the research “the first-of-its-kind comprehensive database of column performance incorporating mechanical bar splices. The results of the study will be used to verify or modify the design of such columns. This research is expected to have national impacts on bridge and precast industries.”
He added that Sjurseth’s work has been to design the test setup, the test specimen, construction and testing of eight columns. “The test setup that Ted has designed is a permanent addition to the Lohr Structures Lab as a new modular lateral testing wall. Ted has shown an outstanding performance in this research.”
Nadim Wehbe, head of the Department of Civil and Environmental Engineering as well as the Mountain-Plains Consortium, said, “We knew Ted was well positioned for great achievements since his undergraduate years at SDSU. Honoring him with the MPC Outstanding Student award is a testimony to his high standing among his peers and to the quality of our graduate students. I have no doubt that Ted will be as successful in his career as he has been in college.”
After graduation, Sjurseth will begin work as a design engineer at the Fort Collins, Colorado, office of Raker Rhodes Engineering, a Des Moines, Iowa-based firm that specializes in building construction, particularly schools, shopping malls and apartment buildings.
