You Have to check this out!!!

[Welder Dave]

Here's one for all you pocket engineer's. How do 40 ton bridge beams bend on their own after being installed? Do you think heat straightening would work?

http://news.nationalpost.com/2015/03...dge-expansion/

[CEP]

I think I know those guys who did the rigging. I worked with them before, they could break a cannon ball!

[Welder Dave]

They're trying to figure what caused it. My off the wall guess would be the beams were held straight when welded and had a lot of built up stress or the welding of the stiffener plates wasn't done properly.

[mechanic416]

The pigeons did it.

[CEP]

It will be interesting to hear what did happen.
When all the I-90 work was going on across Mercer Island to Eastgate. A crew placing the prestressed concrete I-beams didn't secure them properly. Wind picked up over night, and blew the beams over. Prestressed concrete beams are really strong standing up right, not so much on there sides.

[Austin Bennett]

Ouch! Looks like a Friday afternoon "critical lift". When in doubt wait until Wednesday, nothing good happens on a Monday or Friday. It seems the rigger and signal men need new careers. I bet the crane operators will get all the blame, mostly the crane down below. He must have thought the thumbs up from the signal man meant good job

[Jimmy_pop]

since three warped the same way, I'm thinking the earth shifted or something equivalent that caused the "beams" to bend and buckle in the same direction. Crazy regardless.

[mikecwik]

I wonder what the time frame on the movement was......cause I would be like freaking out man.

[geezerbill]

I tried to tell that guy not to weld his section with his 110 volt MIG.

[duaneb55]

Guess the solar storm was more than they expected.

[gxbxc]

Being up in Canada I'd say the polar magnetism is to blame or like mechanic 416 said the pigeons did it.

[Austin Bennett]

In all seriousness, is boom deflection real?

[Welder Dave]

They had 6 in place and were about to place the seventh beam when they noticed 4 of them were buckling. The road could be closed for up to a year and it's a busy road so lots of headaches in rush hour. Will be interesting to see if they can figure out what caused the massive beams to twist like that.

[Kev]

Maybe cold temp in the morning, ends were welded or fastened, then warmer temps came later in the day?

Not the same, but I've seen the electrician's PVC on a 200' barn ceiling, which was installed at 20 degrees, go completely ape when the barn was warmed to 70 degrees an hour later. It can grow two inches with that kind of length. It couldn't expand because of the light fixtures every 12 feet. It was trapped.

Kev

[Welder Dave]

Not too much temperature change. Probably within 5 or 6 deg's on either side of freezing.

[John T]

Meh...

Weld in some cross bracing and carry on...

[burns]

The bridge just has a dogleg now. Don't see what the big deal is.

[Welder Dave]

Probably a million dollar plus mistake.

[OPUS FERRO]

Welder-Dave

Let the video play to the end - it remains as a still-shot - and is the best top-view.

This is what I see in the pics . . .

Viewing left/to/right - beams #6 to #7 [rt. side] - reference: the diagonal cross-ties
on plane, and just above the bottom flanges. They are clearly absent between beams
#4 to #6 in the 'hard-hat' pic - all you see is sun-light ground.

I speculate 'out-board' beams #1 to #2 have the same bottom diagonal bracing.

This bracing effectively boxes 'the parallel', and is intended to serve as a horizontal
'strong-back' to couple the 'sisters'.

From beams #1 to #3 - there is a full compliment of horizontal cross-ties/full span.

Compare the over-head [video] with the 'hard-hat' pic. In the over-head view - the
center section cross-ties are obviously sparse/absent.

If you closely examine still-shot #1 you can see the buckled cross-ties - 'both of
them' [3 pairs] - between beams #3 to #6. Each pair is buckled-up, and consistant
with angle-iron compression failure.

'Fabricated beam hinging' under its' 'own-load' is nothing new. I don't expect the
findings to be an: Engineering flaw - but field 'Lackadaisia'.

Someone decided that: 2/ties x 3 - was just as good as - 4/ties x 4. 'They never got
to 4' - courtesy of: 'accumulative transverse-loading'.

The symmetry of the omited cross-ties produced the 'hinging' wave-form. The 'pairs'
of angle-iron cross-ties were weaker in compression than in tension.

This is why the beams collapsed/folded left.

They had all of the pieces - they just didn't use them.

If you follow the recipe you will get a cake - if you don't - you get Humpty Dumpty.


Opus




.

[DSW]

Compare the over-head [video] with the 'hard-hat' pic. In the over-head view - the
center section cross-ties are obviously sparse/absent.

Yeah probably one of those

"Hurry up! Quit messing with that junk. We can put the rest of those cross braces in later. 3 is fine for now. We need to get these beams set and get those cranes out of here. We're running behind and need to pick up the pace! ..."

[CEP]

"Hurry up! Quit messing with that junk. We can put the rest of those cross braces in later. 3 is fine for now. We need to get these beams set and get those cranes out of here. We're running behind and need to pick up the pace! ..."

Boy, does that ever sound familiar!

[snoeproe]

Yeah probably one of those

"Hurry up! Quit messing with that junk. We can put the rest of those cross braces in later. 3 is fine for now. We need to get these beams set and get those cranes out of here. We're running behind and need to pick up the pace! ..."

Sounds about right.

[Welder Dave]

Those are heavy beams to just bend like that.

[docwelder]

isn't that why they put steering wheels in cars and trucks

[Welder Dave]

I did a little reading today on bridge beams and remembered that they had to delay the placing of the beams because of wind. The wind didn't cause the bending but I now think they may have wanted to make up for the delay by trying to place all the beams instead of individually bracing them as soon as they were installed.