Nix... your engineering thoughts please

[unclehobart]

This is about the West 35 Interstate that collapsed in downtown Minneapolis on August 1st. The bridge was being worked upon for various undisclosed reasons and then collapsed into the Mississippi River. It was an arch truss style bridge that ran for 1,900 feet.

http://en.wikipedia.org/wiki/I-35W_Bridge

Do you know where the inherit stress points are in such a bridge and what has to 'blow out' or degrade in order for the bridge to collapse? Are truss bridges well designed or is too much tension applied to a key key areas?

 

[Nixy]

I don't work with bridges, and while I did take bridge classes in school I'd have to actually sit down and model the bridge to know where the points of high stress are.

That said, trusses are, by definition, designed so that each individual member is in either tension or compression, no torsion or anything of the sort. From what I've seen on the news the whole bridge just collapsed, and noone really knows why. If they didn't have any warning that there might be a catastrophic failure i'd say it's going to be awhile before they have answers...they're going to have to reconstruct and inspect every little piece of that bridge to indentify potential causes of the failure.

 

[Leslie]

I kinda figured it was to do with the whole "there was construction and repair work going on with the joints" thing.

 

[Nixy]

I kinda figured it was to do with the whole "there was construction and repair work going on with the joints" thing.

Maybe, maybe not.