If you’ve ever seen footage of enormous buildings swaying uncontrollably during an earthquake or actually felt the Earth opening under your feet, you would know just how terrifying an earthquake can be. For people in earthquake prone areas who have to endure the natural phenomena on a regular basis, it is important that their homes are safer and more resilient. A project team at Cornell aims to help with that.
Cornell University Seismic Design Team, started in 2013, works to model and prototype earthquake resilient buildings as part of an annual competition, Undergraduate Seismic Design Competition, organized by the Earthquake Engineering Research Institute. For the competition, various national and international teams submit a prototype of a building capable of withstanding varying earthquake magnitudes within certain architectural constraints.
“The goal is to maximize structural resilience of the building while at the same time taking into account other factors such as maximizing building income and minimizing weight,” said Sean Thompson ’18, architectural lead.
Over three years, the team has been evolving its design to ensure that its prototype doesn’t collapse in these testing scenarios that can mimic a magnitude eight earthquake. As Thompson notes, experimentation is key to the team’s philosophy. In the 2015 competition, the team added shear walls — thin plaques inserted between columns to minimize sideways movement — to their design.
“Though a fairly common structural component in areas prone to seismic activity, adding them [shear walls] may have actually lead to the collapse of the structure,” Thompson said. “And once your prototype collapses, it’s automatically placed in a much lower category.”
However, they learnt from this setback and the team managed to place third in this year’s competition that was held in Sans Francisco, California. Much of this success goes to the team’s decision to add super-columns — four columns connected by diagonal braces — to its prototype.“This is something that we came up with ourselves. The main reason you won’t find it in too many buildings is that it does cut a little into the floor space that is available,” Sean said.
To support such innovation, the team is divided into three sub-teams — structural design team, construction team and architecture team — each of which perfects a different aspect of the building.
The structural design team works to generate building models and uses simulation software to carefully tweak each to perform optimally. Since the team also has to demonstrate its ability to construct these structures, a construction team overlooks the design and manufacturing of each component.The architecture team works to design the building with regards to aesthetic appeal and ensures that it abides by the constraints posed by the competition.
The prototypes often have to account for various requirements like certain floors need to be double the height of the others or elements like restaurants need to be included. Part of the competition’s philosophy is to force teams to design earthquake proof buildings that can be used in real environments. This often means that compromising on aesthetics and functionality is impossible.
“We have to satisfy this main requirement to make sure the building withstands these quakes but at the same time we also have these other very real architectural requirements that can sometimes conflict with the structural integrity,” Thompson said.
Despite the team’s success in overcoming many such challenges, Sean is adamant that there are significant obstacles left to tackle.
“We hope to carry out more design analysis and construct several test structures,” Thompson said. “We would use these tests to ensure that the actual software that models deflections is as accurate as possible because in the past we’ve seen error rates of 40 percent.”
Daniel Wilentz ’16, team lead, said that it was extremely satisfying to see their team survive the three shake table tests. He also emphasized the need to help spread awareness about seismology ideas and concepts.
“Our goals are to instil knowledge regarding earthquake engineering within Cornell’s engineering community and foster a stronger desire on campus to learn about seismology,” Wilentz said.
For future semesters, the team hopes to be involved with the wider community by hosting quizzes and trivia that as Thompson puts it, “inspires youngsters to explore the fascinating world of structural design.”
http://cornellsun.com/2016/05/10/student-team-designs-earthquake-resistant-buildings-for-competitionwins-third-prize/
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