Engineering disasters: the Indiana stage collapse

8/16/2011 3:52 PM EDT

I think that is an unreasonable requirement or expectation for temporary structures. Mitigation through evacuation. We'll have to see what the investigation reveals but one change that might have prevented the collapse would be to ensure the covering would "sacrifice" itself and fly off to reduce the wind loads on the rest of the structure. Unfortunately, the engineer loses control of the structure once it leaves the factory and there are any number of (unapproved or unintended) things that the end users will do with these. Given enough time or money you can do almost anything. Question is, will someone want to pay for it?

8/16/2011 4:20 PM EDT

It was reported that the NWS issued a high wind warning only 10 minutes before the disaster. In my part of the country these warnings are typically not issued until the weather event is directly overhead. Maybe a little less reliance on computer models and more human judgement at the NWS offices could get these warnings out sooner.

8/16/2011 5:00 PM EDT

Given the exposed nature of the stage at the fair it would be hard to protect it and fair goers from injury/damages. I wonder what type of connection with the ground was made? What if the structure was reinforced with strong guy wires that both held it down in place and prevented side to side swaying? I was wondering what (if any) covering was on the top structure of the staging; if it looked like an airfoil to the winds then there could be a unintended set of stresses on the structure. Given the temporary nature and the possible onsite setup/assembly it is possible that the best engineered structure would not survive high winds (if for example the right number and type of connectors were not used). Just wondering, my heart goes out to those who lost loved ones and to those recovering.

8/16/2011 5:38 PM EDT

ummm...is this EE related?

8/17/2011 1:32 AM EDT

Dashpots, springs, and weights can be modeled electrically. Can a truss be modeled electrically?

To what extent could a structure like this be scaled down and subjected to wind tunnel tests? Also, with the continued miniaturization of sensors, it seems with some structures you might be able to create a network of stress sensors and start taking data on the forces they are subjected to.

8/17/2011 11:52 AM EDT

Guy anchors can be setup quickly and economically and have proven themselves reliable in stabilizing countless numbers of guyed antenna towers in hurricane affected regions.

8/19/2011 6:17 AM EDT

I feel this stage is built by freshers. The experts look for all these kind of troubles before hand and give provisions to handle these situations safe to the lives.

8/19/2011 9:05 PM EDT

Could have been a resonant oscillation in the canopy and a particular wind speed and direction. In my experience with airfoils, these can grow exponentially and quickly blow up a structure.

8/20/2011 12:01 PM EDT

I have seen stage rigging that was suspended from a large crane. In case of emergency it could swing the entire structure away from the audience. That was back in the early 1980s.

8/23/2011 1:52 PM EDT

I didn't see any rigid cross bracing or guy cables that should have prevented sway or buckling of the support columns. Once the back edge dropped the next row of supports tilted forward and everything else then went forward and down to the stage platform.

8/23/2011 2:56 PM EDT

From camping with pop-up canopies you find out the you need two guy wires per corner or it will collapse or fly off the same way in the wind. Another way is to put guy wires in Xs on 5 sides of the cube and nail that puppy down. Use both techniques and that canopy will not budge much. The fact that these guy wires where not put on should be looked into.

9/2/2011 10:24 AM EDT

wind tunnel load testing, idiots