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Message: [QUOTE="Ottoble, post: 1463635, member: 2539"] This is scary stuff, especially for those of us that visit sites all the time. Really good to see that no one has life threatening injuries, those guys work their butts off and we all know it's a dangerous job but nobody deserves this. Hi CL my feeling is that's unlikely since the crane is not tipped over as it often is in overloaded crane collapses. The crane operator may have made a mistake and bumped the building however though usually small bumps are accounted for. It hasn't been very windy this week so I'd think a wind event but that can't be ruled out also. With these Pre-Engineered buildings sequencing is very important as they are designed to the absolute limit of the building code. the construction must start at frame bays with bracing that is designed for wind/earthquake loads but also sized for temporary construction loads, wind on the frame, mild crane bumps, erection adjustments and the like. In watching the video a few times I didn't see any clearly visible bracing which would generally be pretty obvious as rod Xs on the sides and up the roof line between one of the bays in a sea of purlins framing left to right. The light purlin beams running across are very cost effective for spanning to carry the roof but because of that have only a small amount compression strength to transfer minor loads from frame to frame. Since the accident was 8:15, early the construction day, it is also possible that the crew forgot to put in nuts the last bay of anchor bolts at the end of the day yesterday, and proceeded this morning with work on the roof and putting up the next frame without installing them. The tip of one full bay frame could also cause a domino type collapse like this also if not connected to the purlins. The left out bracing, a wind gust or crane bump, would be my suspect for the most likely cause, but my it may be a combination of the two causes resulting in this really sad event. [/QUOTE]

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