Sunday, 14.Apr.2024, 8:42:25
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     Dr.(Phys.)Dipl.-Ing.Ralf-Udo Hartmann

According to officials

When the stage collapsed at last weekend's Indiana State Fair, most people figured it was the 60-70 mile-per-hour winds that were just too strong for the stage setup to take, however, officials investigating the incident have a different idea of what may be to blame....a tarp. Or more accurately, the stage roof's center plug.
According to officials, the center plug, a section in the center of the stage which serves as a wind pressure release device on a canvas stage roof, had come loose earlier in the week in moderate wind and had to be re-attached.
Now the question is was it re-attached too securely?
According to officials, the center plug is designed to rip away to help get rid of wind pressure in the event of strong winds like that of Saturday. Unfortunately, the plug may not have worked properly and instead stayed put and acted like a sail. From Indiana's Channel 4: "Based on the videos I’ve seen it looks like the wind gust got up under the roof top," said Tim Todd, Purdue University’s Assistant Director of Technical Services and a veteran concert stage supervisor. "If you watch the video you can see the roof top billow up."

Video of the stage collapse shows the center plug flying loose a split second before the left stage skin releases immediately before the stage begins to buckle and fall.
A source tells Fox59 News that center plug is designed to come loose at wind speeds of approx. 20 miles per hour in order to relieve air pressure on the rest of the roof.

Collapse video shows the center plug clearly holding in place until winds reached approximately 70 miles per hour even though concertgoers say the wind had been increasing in the minutes before the collapse. "We had a wind gust that came at the right angle, caught the roof top and the truss the right way and was too much for what was engineered," said Todd. "If the roof tears away instead of putting that type of loading force on it, maybe the structure doesn’t come down and the worst thing we have is a 40 x 80 feet of tarp flying through the fairgrounds causing trouble."
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