Who Broke The Bridge?

[2LaneCruzer]

Chinese steel...

 

[dusty3030]

Chinese steel...

Doubt that. They started construction on it in 1967.

At this point who knows exactly what caused it. The fracture is near the center pier so right smack dab in the middle of the bridge. The bridge itself is over a mile and a half long. The spans between piers over the river are around 1,000 feet long. So the break is at end of a 1,000 foot span.

We had record cold for an extended amount of time this past winter. They did a ton of seismic retrofitting and upgrading to the bridge over the past 10 years or so. They supposedly upgraded it to withstand a 7 plus earthquake since we are in the New Madrid fault zone. Did any of this contribute to it? Who knows at this point.

Hopefully they'll reopen river traffic this week. I watched the press conference yesterday and the chief engineer for TDOT said they were running calculations to understand just how stable or unstable it is at this point.

 

[ArlyA]

Some engineer my have got a decimal off. Not likely because it was cool for a few weeks. Things do break sometimes.

 

[caver]

They call it a crack...I call that a break.

 

[PILOON]

That beam is 24" X 30" and cut clean thru.
Yet they call it a crack?
That is a break!
Clean one at that.

The sound of that box beam popping must have been heard for miles around.

Also , from photos, there is also a minor gap between the 2 sections as well as some deflection.
That suggests there might be a lack of expansion joints somewhere along the line.
It took some major stresses to snap that huge box beam!
Earthquake?

LOL, next they'll blame bird poop that caused corrosion, but actually not so funny as that has been the cause of some bridge failures. But this structure does not seem to offer bird nest opportunities.
Usage of rivets was common practice and has the advantage of not annealing the metal either.

Guess they would next want to Xray all the other similar locations for safety sake.
But then all those suspension cables did a fine job holding things up.

 

[Larry Caldwell]

With no traffic ON the bridge, I would think there would be less threat to barges passing under it with speed controls and USCG monitoring.

Engineers are working long shifts trying to figure out if the bridge can hold itself up. That fracture is near the center of the span, and it's going to take some work to decide if it can stand repairs or needs to be demolished. It may possibly be able to support reduced traffic, but probably not any truck traffic for months. Barge traffic will resume when they are sure it won't fall down by itself.

It was inspected late last year and the fracture did not exist then. This is a recent failure that may affect other structural members.

 

[dodge man]

Let’s see, I had a structural analysis class in 1983. I think the moment around the pier is = to the dead load + the live load divided by the square root of pi. The answer is 3.

 

[Darryle]

Totally unrelated, but how do they set the rivets on a beam like that?

 

[Streetcar]

I google it to see its a suspension bridge. Diagnosing the stress on that beam, is above my pay grade..

Tied arch bridge not suspension
Bolted not riveted
Failure appears to be fatigue at weld
Beam looks to have minimal rust and section loss

 

[Streetcar]

FYI the last major river bridge that used rivets was completed in 1963