Posted on 01/24/2017 8:11:35 PM PST by Tolerance Sucks Rocks
An apparent construction error six decades ago could have caused the fracture discovered Friday in a steel beam that forced the closure of the Delaware River Bridge, an engineering expert who viewed pictures of the cracked truss said Sunday.
An image of the cracked truss - a supporting piece - on the bridge that runs between Bucks County in Pennsylvania and Burlington County in New Jersey shows signs of holes that had been mistakenly drilled into the steel beam and then filled with plug welds, a typical solution in the 1950s when the bridge was built, said Karl Frank, professor emeritus of engineering at the University of Texas at Austin. His areas of study include fractures and fatigues in metal structures and welded and bolted joints, according to the university website.
The image is on the website of the Pennsylvania Turnpike Commission, and Frank viewed it there.
"What we do nowadays, we don't do that," he said. "If you have a misdrilled hole, you would just put a bolt in and tighten it up. The problem is they welded it up."
The plug welds created a weak point, Frank said, and the stress of traffic crossing the bridge continuously since it opened in 1956 could have led to a sudden crack, splitting the beam at the welds.
A spokesman for the commission, which operates the 1.2-mile-long bridge jointly with the New Jersey Turnpike Authority, did not dispute Frank's conclusion, but said turnpike engineers had too little information to confirm anything about the crack's cause.
"Don't want to make premature assumptions without science," said Carl DeFebo Jr., the spokesman.
(Excerpt) Read more at philly.com ...
You just put a bolt in it. Brilliantly simple solution.
Shave signs were larger in your neck of the woods back in the day?
It didn’t look like a Capital I beam...
In this case, more of an H Beam (Piper?)
No. Just more of them
Thanks, I see the H shape now.
Unsettling because I drive a fully loaded 18 wheeler over that bridge at least once a week.
Do not pass, On a Slope, Unless you have, A periscope, BS...
Yo!
Time to search Burma shave
I miss the Burma shave signs.
That detour looks like a pain in the rear; this is a very busy bridge. Sadly, many of these older structures throughout this area are in need of maintenance or replacement but the money just isn’t there...
195 to 295 to 95 or over the Betsy Ross or Burlington Bristol or some other nightmare. I told my dispatcher to send me DC to Boston runs until this is fixed.
Saw what you did there, I did. And the professor HAZ it exactly right that a properly hot-riveted plug would have been preferable. I'm doubtful they had a good understanding of the HAZ in the 50s since mobile radiographic inspection equipment was probably not available. I could be wrong about that, though.
The detour graphic on the news (News 12 NJ) looked so far out of the way; hopefully there is much less traffic in general down there (as the population is less dense than up here between Newark and Jersey City).
Excellent.
“...unsettling...”
Although this is not as dramatic as your story; I was just on that bridge a couple of weeks ago driving our daughter to college in Philly.
Stay safe out there!
The plugs are along the transverse line rather then through the side. I don’t see how holes could be drilled several feet into the end of the member and then plug welded
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