For the structural engineer types.

[never_retreat]

How does this happen?
http://nj1015.com/nj-turnpike-connector-bridge-now-closed-indefinitely-because-of-broken-beam/#photogallery-1=4

[just Warren]

It done busted.

[bedlamite]

Tough to tell from just a pic, but it's probably fatigue from carrying way more traffic than it was built for 50 years ago.

[Brad Johnson]

Microscopic crack, salt-laden air, 1950's metallurgical technology, and half a century of vibration and thermal cycling.

Brad

[MechAg94]

Microscopic crack, salt-laden air, 1950's metallurgical technology, and half a century of vibration and thermal cycling.

Brad

A flaw or some sort of corrosion is the only thing I can think of.  Otherwise, I would have expected it to fail closer to all those bolts. 

Nice paint job.  Is that recent?

[Hawkmoon]

That's not a shear crack. A shear crack wouldn't be perfectly vertical. Given that it's near an end, and the end was plated to add resistance to shear but the failure is just beyond the reinforced zone, I sort of suspect (without enough information to go on) that it might be the result of excessive longitudinal movement at the ends. (In other words, it just pulled apart.)

The article says it's part of a truss. In a truss, there's very little bending stress because all loads are redirected to be axial to the truss members. The top chord (which the broken member appears to be) does take some bending, but a fracture due to bending wouldn't be that vertical. I think it was caused by either the bridge supports shifting, or else the design was faulty from Day One. They need to do a lot more than just fire up the welder and stick the two pieces back together.

[zahc]

60 years? How long do we expect bridges to last?

[lupinus]

Just put a few wraps of duct tape, it'll be fine

[Tuco]

60 years? How long do we expect bridges to last?

Fifty years.

[dogmush]

When was the last time the NJ Gov crossed that bridge?

[RoadKingLarry]

60 years? How long do we expect bridges to last?

k

Let's ask the Romans.

[charby]

Tough to tell from just a pic, but it's probably fatigue from carrying way more traffic than it was built for 50 years ago.

I agree, weakest point decided to quit.

[never_retreat]

A flaw or some sort of corrosion is the only thing I can think of.  Otherwise, I would have expected it to fail closer to all those bolts. 

Nice paint job.  Is that recent?

Somewhere I read the painters found the crack.
That paint looks new, but the break area is not painted. So who knows.

NJ usually does not maintain bridges, they wait for them to fall apart the way someone can get there pockets lined on a over priced contractor to replace it.

[230RN]

Judging by the aerial pic in the article's slide show it kind of looks like they should have put another expansion joint right about there.

There's what looks like a bigger expansion joint right where the bridge starts to cross the river.

Looks like a tension break in hardened steel.  No "draw down" in dimensions right around the fracture.  Just a "pop" where it let go.

It's hard to tell in the dark photo from underneath, but it looks like two of the members broke.

I'll bet it was a pretty cold night when it happened, but no way to know for sure.

[never_retreat]

Judging by the aerial pic in the article's slide show it kind of looks like they should have put another expansion joint right about there.

There's what looks like a bigger expansion joint right where the bridge starts to cross the river.

Looks like a tension break in hardened steel.  No "draw down" in dimensions right around the fracture.  Just a "pop" where it let go.

It's hard to tell in the dark photo from underneath, but it looks like two of the members broke.

I'll bet it was a pretty cold night when it happened, but no way to know for sure.

Yep 2 broke.

[RoadKingLarry]

Duct tape.

[Hawkmoon]

Duct tape.

Detcord

[dogmush]

Yep 2 broke.

Pretty sure that's a single "I" beam.

[never_retreat]

Pretty sure that's a single "I" beam.

Its 2 pieces of flat stock.

[dogmush]

Its 2 pieces of flat stock.

You sure?  In addition to it being labeled an "I" beam in that article, I can pretty clearly see the web in the picture I quoted.  The web is oriented horizontally.

It would be pretty strange to build a bridge truss out of flat stock.

[Hawkmoon]

You sure?  In addition to it being labeled an "I" beam in that article, I can pretty clearly see the web in the picture I quoted.  The web is oriented horizontally.

It would be pretty strange to build a bridge truss out of flat stock.

The article doesn't say what it is, it refers to the "steel member." The headline for the article refers to it as a "beam," but it doesn't say what kind of beam, and the article wasn't written by a structural engineer nor was the headline. I looked at the photos again, and I don'y see any web section there. If you can see one, you have better eyes than I do. That said, if it is a beam rather than a pair of parallel flat sections (which would make sense), it isn't an I-beam. From the close up of the fracture from the outside you can see that the fractured plate has squared corners and parallel faces, so it definitely isn't an I-beam. It might be a wide-flange, or H-beam, but definitely not an I-beam.

[K Frame]

Pretty sure that's a single "I" beam.

No, it appears to be two pieces of flat stock.

Not every steel beam used in construction is an I beam.

Take a look at the original picture in the first post.

You don't laminate I beams like that.

I can't be sure, but I don't think it's an H beam, either. Might be, but the pictures aren't clear enough.

[dogmush]

Clearly someone from APS needs to go to Jersey and settle this. 

So I'm bored today, and had some time to Google.  I'm saying again that's not flat stock.  it my bean H-beam (I confess, I had forgotten the differences between H and I) but there is definitely a web there.

I present my evidence for my last try: 

1. Linked article labels it an "I beam".  Not the most compelling I know, what with journalistic standards being what they are, but hey, they might be right.


2. Look at the diagonal beam coming up to the lamination.  On the outside you can clearly see four rows of bolts with a gap in the center.  This pattern is copied on the horizontal beam.  Now look at the inside of the diagonal truss.  You can only see the heads of two rows of bolts.  That's because the other two rows are on the other side of the web, and hidden from view.  The beam's web lies in that gap between the rows of bolts.


3. I took a screen shot of the pic quoted above and yelled "Enhance" at my computer in an attempt to correct for curmudgeon eyes.  Compare the depth of the beam on the inside of the bridge (full depth) vs the depth on the outside.  You can (i can anyway) pretty clearly see that there is a horzontal chunk of metal about half way up.  Also you can just pick out the rows of bolts again.  The "outside" face has 4 rows, and the inside only has two, because the top two rows are hidden by the web.


We can know return to our regularly scheduled kvetching about cornbread and plotting things to wrap with bacon.

[lupinus]

Rub some dirt on it, it'll be fine

[K Frame]

OK, your enhanced picture does show what appears to be an H beam.

That said, it's not uncommon for the top chord of the truss to be multi-part flat stock connected by supports for bearing members for the deck above.