Freak of Nature or Design Flaw?

The 70 people inside the Dallas Cowboys practice dome who sprinted for their lives when it collapsed, say before it went down everything was swaying and moving.

Experts say some of the clues to what happened may be in the dramatic video that was taken just as the facility collapsed. Some think there may be the possibility of a building design flaw.

One of those is University of Texas at Arlington Structural Engineering Professor Dr. Ali Abolmaali. Abolmaali, who has reviewed high-profile structural collapses around the country took at the video shot by 33 News as the facility came down. Because of the severe vibrations, Abolmaali suspects there was more at play than just wind. "It is surprising to see 60-70 mile an hour wind collapse a building. So wind itself was not the cause, it may have also been something else with it".

Abolmaali says the video indicates there may have been what is an engineer's worst nightmare, resonance. Experts describe that as a wind-induced design flaw where the building shakes itself to collapse. It was resonance that destroyed the Tacoma Bridge in dramatic style decades ago. The collapse can be found on internet videos, showing the bridge looking almost like a noodle before it fell.

Experts say the massive Cowboys facility that was 88-thousand square feet was vulnerable to wind because of it's size. It hadn't been structurally inspected since it was built in 2003. But, to get the green light back then, city officials in Irving say it had to pass design code. "There was a code requirement back then that said it must withstand 90 mile an hour wind gusts for up to 3 seconds", says Gary Miller, Irving Director of Planning and Zoning.

The National Weather Service confirms a microburst hit the area with winds up to 77 miles an hour when the facility came down. The Pennsylvania company that built the canopy, Summitt Structures, calls it a "severe weather event", seeming to blame mother nature for the freak collapse. Investigators with OSHA say it could take up to six months to rule on the collapse.