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Not quite a disaster but interesting

Not quite a disaster but interesting

RE: Not quite a disaster but interesting

Might be interesting to see what Arup comes up with for cause of the bolts shearing off and falling.

Those are large bolts! (size of a human arm).

I think there were falling bolts discovered many years ago by a custodian inside the Kemper Arena (I think) and that lead to a major repair/response.

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RE: Not quite a disaster but interesting

Jed - maybe it wasn't the Kemper but I seem to remember a story about a janitor cleaning one day and finding a structural bolt on the floor and reported this. They eventually discovered a flaw in the design of an arena roof and had to replace numerous bolts, etc. Not sure where that was.

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RE: Not quite a disaster but interesting

"there is no risk to the structural integrity of the building".

Yup, nothing to see here. [sarcasm]6-inch thick bolts 2 or 3-feet long are inconsequential to any design, and we really didn't need them. The engineer just spec'd them so he could look smart.[/sarcasm]

RE: Not quite a disaster but interesting

JAE,

In one of his books, J.E.Gordon mentions a ship's cook who noticed a crack in the floor of his kitchen (galley?). He reported it to the captain, who told him not to worry about it. "Being of scientific bent", the cook started to mark the dates next to the end of the crack as it propagated along the floor. When the ship split in half, the dates turned out to be on the half that stayed afloat. This has provided much knowledge of crack propagation.

No mention of whether the cook survived.

--
JHG

RE: Not quite a disaster but interesting

"No mention of whether the cook survived."

Assuming bigears that this was a 'Liberty Ship' in service in the middle and northern Atlantic routes, and that the cook was on-duty during the breakup, he died. Damn shame, too.

RE: Not quite a disaster but interesting

Duwe6,

Probably, he survives if he is on the part that floats. He has some change, possibly very small, of scrambling to the floating half if he is in the water.

--
JHG

RE: Not quite a disaster but interesting

(OP)
Yes, The usual cop-out. The investigation is probably complete. Now the lawyers will take months to gut the report of anything meaningful.

RE: Not quite a disaster but interesting

The Leadenhall Building !!! That is interesting, wasn't that long ago there was a documentary on the telly praising the modular technique used in its construction. Will be interesting to see what turns up, if it's heat treating, hydrogen embrittlement, or something else. I'd be curious to know the country of origin of those bolts.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: Not quite a disaster but interesting

One bolt was from the 5th floor and one from the 15th floor.....big difference in time of application between these two. Not likely from the same run of bolts....that would make me look closely at lateral drift and fatigue.

RE: Not quite a disaster but interesting

Drawoh,
That cook probably survived only to be fired.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

RE: Not quite a disaster but interesting

Hydrogen embrittlement can be classified into two categories:

Quote (ASTM F2078 Standard Terminology Relating to Hydrogen Embrittlement Testing)



internal hydrogen embrittlement (IHE)—hydrogen embrittlement caused by absorbed atomic hydrogen from any chemical process that introduces hydrogen into the steel before exposure to an externally applied stress.

environmental hydrogen embirttlement (EHE)—generally caused by hydrogen introduced into the steel from the environment after exposure to an externally applied stress.


IHE typically is process related, and EHE typically is environment related. A recent civil engineering example of EHE is the occurrence of fractured threaded rods for the San Francisco-Oakland Bay Bridge, with information here:

http://baybridgeinfo.org/rods

RE: Not quite a disaster but interesting

Curious only one bolt from each location. Each connection contains multiple bolts. Back in the late 60's/early 70's, we had batches of SHCS bolts that were popping the heads 1 to 2 days after being torqued into their assemblies. It was inconsistent, with maybe 20% exhibiting the failure. I was a student with "zero" technical knowledge at the time, so I don't recall what the outcome of root cause was, but it was isolated to one lot number of hardware. It was just reported this morning that a third bolt has failed. My money is on the hardware metallurgy.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: Not quite a disaster but interesting

My previous quote was from the 2001 edition of ASTM F2078. The 2008 edition made some changes:

Quote (ASTM F2078 Standard Terminology Relating to Hydrogen Embrittlement Testing)


environmental hydrogen embrittlement (EHE)—hydrogen embrittlement caused by hydrogen introduced into a steel/metallic alloy from an environmental source coupled with stress either residual or externally applied.

internal hydrogen embrittlement (IHE)—hydrogen embrittlement caused by absorbed atomic hydrogen into the steel/metallic alloy from an industrial hydrogen emitting process coupled with stress, either residual or externally applied.

RE: Not quite a disaster but interesting

Quote (wannabeSE)

Reminds me of the breaking bolts during the construction of San Francisco's Bay Bridge. If I remember correctly, 3" anchor rods failed.

Yep, and one heck of a retrofit using PT in every-which-way of directions...

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