Sugarland in Indiana had 2300 pound concrete ballasts sitting on pea gravel.Don't they usually have long, thick, heavy steel spikes into the ground to hold the guys? Otherwise you'd be looking at several tons of ballast per guy wire (i.e. more than the wire's breaking strain) to avoid the whole shebang taking off. Like it did. I'm thinking of the huge spikes they use to anchor big tops and the like.
Wouldn't the gravel act like ball bearings, reducing the coefficient of friction, actually making the ballasts easier to move?had 2300 pound concrete ballasts sitting on pea gravel.
Those were K-rails, right? I've heard the "standard" is the mafia block, a 3'x3'x3' cube of solid concrete weighing about 2T (4000 lbs.), with rebar "handles"/anchor points.had 2300 pound concrete ballasts
Derek, the person I was talking to actually used the term 'Jersey Blocks'. I've only ever heard the highway divider thingies called Jersey Barriers. Yes, the point the person I was discussing this with was making is that they just slid across the gravel. Also, apparently the 'ground' in the stage area was new solid on top of the mud bog area.Wouldn't the gravel act like ball bearings, reducing the coefficient of friction, actually making the ballasts easier to move?
Those were K-rails, right? I've heard the "standard" is the mafia block, a 3'x3'x3' cube of solid concrete weighing about 2T (4000 lbs.), with rebar "handles"/anchor points.
Somewhere I have the Thorton-Tomasetti forensic engineering report of the Indiana State Fair blow-down, and the Witt Associates review of the Fair's emergency operations plans. T-T identified a number of deficiencies that individually would be catastrophic depending on how the failure initiated. The loss of upstage guy anchoring was the initiating failure in Indiana. My recollection is the Fair wanted to add another lane of vehicles back stage (trucks, buses) and had the staging company extend the guy points further up stage where there were no permanent anchorage points and Jersey barrier was used. Not every piece of barrier was on gravel, so T-T did pull testing on wet gravel, wet asphalt, and maybe wet grass. It took surprisingly little lateral force to move the ballast, and once the guy lines took slack the structure was doomed to gravity.Derek, the person I was talking to actually used the term 'Jersey Blocks'. I've only ever heard the highway divider thingies called Jersey Barriers. Yes, the point the person I was discussing this with was making is that they just slid across the gravel. Also, apparently the 'ground' in the stage area was new solid on top of the mud bog area.
That was my thought, too.Wouldn't the gravel act like ball bearings
Yes, that's exactly what happened.That was my thought, too.
We use essential cookies to make this site work, and optional cookies to enhance your experience.