What Murrah building has in common with a galaxy note 7? One can say they both failed to perform as expected . The same person can also point out they both need engineers to figure out what went wrong.
On February 28th, SEI graduate chapter of Virginia tech invited Dr. Osteraas, group vice president of Exponent Inc., and Andrew Hardyniec (VT Alumni working at Exponent) to talk about structural failure and how Exponent helps to “unravel the mystery”.
The presentations were quite amusing and fun to listen to. Two interesting takeaways:
- Murray progressive collapse was due to the extra upward forces to the floor slabs, causing their collapse. The extra force on the slab was way beyond its intended design forces. This is different from analytical approaches where we remove a column and measure the rotation or vertical displacement at the removed element’s node
- There was no problem with the design of World Trading Center. While the twin towers were designed to withstand airplane impact, they were not designed to sustain the explosion of plane fuel. However, they did not collapse immediately and gave enough time to occupants of the lower stories to get out. This is the most we expect from a building under low-probability high-impact hazard: to give enough time before they fail, so people can have a shot at surviving.
A lot of graduate students from different departments stayed after the presentation to talk to speakers and ask about possible job opportunities. I asked Dr. Osteraas about the future of natural hazard engineering and what would be hot in the coming years. He pointed out that climate change will be a big part of it. Interestingly, even those who deny it, are concerned about the vulnerability of their structures in the rapidly changing environment. After all, one (hopefully) cannot fool him/herself.