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The Seismic Design Team put their latest balsa wood structure to the test at the annual Earthquake Engineering Research Institute conference 

David Balcells & Michael Nietes | Photos Courtesy of Seismic Design Team

Every year the Earthquake Engineering Research Institute (EERI) hosts a conference where members of industry, students, and faculty gather to learn about advancements in the research of Earthquake Engineering. These conferences center around the seismic design competition, where teams from different universities construct a balsawood structure and present it in front of a panel of engineers. The structures are then tested on a shake table to simulate different ground motions. This past March, the conference took place in Vancouver, British Columbia, where the CU Boulder EERI student chapter had the opportunity to compete in the seismic design competition. 

Preparation for the competition started in the Fall 2018 semester, when the team started formulating ideas for their structure. This year, the team got to design a building with a base floor plan in the shape of a “T”, which presented several challenges since the floor plan was asymmetric and the team had no prior design for reference. Designing a structure that fit these specifications was no small task, especially because the team had just lost most of their seniors the prior year. 

“The team got a lot smaller since all of last year’s seniors graduated. This made it a great opportunity for me to get more involved, though, and those of us still around were hard working,” returning member and Civil Engineering Junior Lauren Kerchval said. “For example, I got to write a lot of the proposal and practice technical writing this year, whereas I did not help too much with writing last year.” 

During the design process, several floor plans were drafted in AutoCAD and Revit, after which the construction process began. Columns, bracing, and other structural components were laser cut and assembled using super glue. As the structure was being built, other team members ran analyses on the structure to predict building accelerations and displacements using a program called SAP 2000.

This was by far the greatest challenge the team faced throughout the year since none of the members had any experience using the program. “I think the biggest challenges that we faced had to do with our understanding of the rules and specifications,” Kercheval said. “Even with all of the help we did get, a lot of things we had to figure out on our own.”

At the conference, Varela and Kercheval presented the structure, discussing the structural aspects of the building and the architectural pieces that complemented the building in front of a panel of engineers. “I had to get a major crash course on the design and structure of our building in order to prepare for the presentation,” Kercheval said. “It definitely makes me want to be more involved in the design this coming year so that I will know all of the details behind the design decisions.” After their presentation, the panel followed up with several questions to challenge the design of their building and the presenters were able to answer each question with confidence and poise. 

The following day at the competition was shake day, where each team tested their building by placing it on a shake table and simulating two different ground motions. Since 38 schools were present at the conference, the team was able to observe many structures and take note of the various design aspects that worked well for other teams.

“Shake day is always one of the most fun days of the week,” Kercheval said. “Although it is a competitive environment, everyone wants to see other teams succeed during shakes. There’s a sense of camaraderie amongst all of us engineers as we hold our breath as a building begins to collapse and as we cheer when a building survives GM2. It’s exciting to see if your design and hard work will make it through.” 

The team’s building survived the first ground motion. Unfortunately, the building was not able to withstand the seismic loading of the next ground motion, which ended up shearing the building right off of its baseplate. Miraculously, the building did not fall off the shake table. Instead, the building was able to stand tall and “dance” on the base plate to the amusement of other students and faculty in the crowd. 

“Personally, I was super anxious going through the shakes,” Kercheval said. “The first GM was relatively uneventful – it didn’t even look like our structure budged. For the second though, I thought it was going to fall over, but it never did! I was hopeful that the judges would not consider it collapsed even though it completely sheared from the baseplate. I was not sure what the rule was at the time, so I was excited to think that our structure survived. Even despite the actual results, I am incredibly proud of the work we did.” 

While the building was not a complete success, the team learned what it takes to design and construct a building that can withstand several ground motions. Equipped with more knowledge and more motivation to improve over the past year’s performance, the team will look to find a new level of success when they travel to compete again in the beautiful city of San Diego. 

Kercheval is excited to work towards the next competition. In reflecting the opportunities the Seismic Design Team has presented her, she said, “Having the opportunity to experience the competition with my peers is incredible. Not only is it a chance to get to know the members of the team and students from other schools, but there is always so much to learn. Other schools are so talented, so it’s great to talk to them about their ideas and be inspired by their creative architecture. Being a member of the SDT constantly reminds me of my passion for structural engineering. I want to design a building one day that actually will withstand a megathrust earthquake – and this gives me the chance to try it out!”