MS student researches seismic design of deep bridge pier foundations

Coming from Wisconsin, graduate student Aaron Shelman is not afraid of the cold. In fact, he likes it so much that he is using liquid nitrogen to create subzero temperatures year round. As a civil engineering graduate student with an emphasis in structural engineering, Aaron has been researching the effects of seasonal freezing on soil-foundation-structure interaction.

Aaron’s major professor, Sri Sritharan, introduced him to the need for more research and better construction of bridge columns that extend into the ground and act as foundations. The main research objective is to design these foundations to withstand seismic activity under both warm and wintry conditions, which are experienced in several seismic regions of the country. This is especially important because some of the largest earthquakes in the history of the United States—such as the 1811–1812 New Madrid series of earthquakes and 1964 Great Alaska earthquake—have occurred during winter months. Funded by the Alaska University Transportation Center and the Alaska Department of Transportation and Public Facilities, his research has examined how these columns will respond to movements in the earth when subjected to seasonal freezing. Aaron’s focus is on the development of an analysis model that can account for the changes in material properties in this frozen state and their impact on seismic response of the foundations and bridges.

In the lab, he has been running tests on confined concrete samples at cold temperatures to examine their structural properties and comparing them with current models developed for warm conditions. The idea is to ensure that concrete “goes with the flow” at all temperatures, so that structures will maintain the same weight-bearing capacity but can withstand the large movements typically associated with earthquake loading. His labors will result in safer, more reliable construction of these types of columns in the future.

A graduate of the University of Wisconsin Platteville with a BS in civil engineering, Aaron was drawn to Iowa State’s graduate engineering programs by the opportunities that would be available to him. Some of his peers from Platteville had already begun their graduate work at Iowa State, and he was especially impressed by the civil, construction, and environmental engineering department. He thinks one of the best things about his experience has been expanding his knowledge through his coursework and by observing his peers’ research in other areas of civil engineering.

Aaron will finish his master’s degree this semester and plans to immediately begin a doctorate in civil engineering with an emphasis in structural engineering. As part of his thesis he has created an analysis method for structures in cohesive soils because that is where the largest deficiency in current practice exists. As he continues his graduate career at Iowa State, he will expand his research to examine how this issue applies in other soil and foundation types.

 

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