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Thread: Stud welding and the Mexico bridge collapse

  1. #1
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    Stud welding and the Mexico bridge collapse

    https://www.nytimes.com/interactive/...ain-crash.html has some clear pics. I've never run a stud gun (except the little auto body variety) so I'm curious what causes poor penetration in typical use.

    What do those with experience see in those pics and how do you personally set and test a stud gun before welding? What amp range would be typical for that job?
    Last edited by farmall; 06-13-2021 at 09:13 AM.

  2. #2
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    Re: Stud welding and the Mexico bridge collapse

    I get some kind of error message on that site, perhaps because of mobile phone? Something about limited articles.
    1st on WeldingWeb to have a scrolling sig!



  3. #3
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    Re: Stud welding and the Mexico bridge collapse

    Quote Originally Posted by Oscar View Post
    I get some kind of error message on that site, perhaps because of mobile phone? Something about limited articles.
    Its not your phone they want you to subscribe. I think if you want to give them your email and create an account, then you can read a limited number of articles per month. I was offered a limited time deal of $0.50 CDN/week for 1 year as opposed to the regular price of $5.00/week. Not that important to me.
    ---Meltedmetal

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  5. #4
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    Re: Stud welding and the Mexico bridge collapse

    The link came up for me and I just clicked no to subscribing. Politicians whether they be local, by district or federal should never be the ones deciding when large projects should be in service. Ie/ they shouldn't be using the project for political gain. 3rd party inspections by qualified firms should be mandatory and any deficiencies be corrected before it goes into service. I don't think the studs breaking or improper welding on them is the main cause of the failure but certainly contributed to it. I think insufficient cross bracing was a big factor and it sounds like the welds on them were suspect too. The main beams weren't tied to each other strong enough to carry the weight over 100's or thousands of cycles. The concrete tied to the studs was supposed to add some structural strength. Poor workmanship, poor engineering, poor quality control and poor inspection caused the failure. Politicians pushing for it to be open by a certain date sure didn't help.

    We had a bridge here a few years ago fail while under construction because the contractor installing it got in a hurry. The huge girders (40 tons) buckled and had to be removed to get straightened. The contractor tried to take a short cut and the cross bracing failed which caused the girders to buckle. I don't know why they don't specify heavier cross member support considering it's a bridge and the extra weight wouldn't make a big difference. Would have been cool to see how the huge girders were straightened. The contractor paid dearly for their mistake though. The largest rubber tire crane in the area(1200 tonne Liebherr LTM11200-9.1) had to be brought in to stabilize the structure while the beams were removed and that in itself was a major accomplishment.

    https://www.news957.com/2015/07/20/n...n-bridge-city/

    https://canada.constructconnect.com/...onton-1007773w

    https://cranenetworknews.com/ncsg-br...k-in-edmonton/
    Last edited by Welder Dave; 06-13-2021 at 07:23 PM.

  6. #5
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    Re: Stud welding and the Mexico bridge collapse

    Here's a pic from the NYT piece showing the welds.

    Their link does not require a sub but their web design is mongtardedly stupid.
    Attached Images Attached Images  
    Last edited by farmall; 06-13-2021 at 08:42 PM.

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    Re: Stud welding and the Mexico bridge collapse

    Once you read some mysterious number of articles in a month(I think) they will ask you to subscribe.
    ---Meltedmetal

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  9. #7
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    Re: Stud welding and the Mexico bridge collapse

    Quote Originally Posted by Meltedmetal View Post
    Once you read some mysterious number of articles in a month(I think) they will ask you to subscribe.
    I'm in the habit of beating paywalls by clearing cookies and having multiple browsers (also nice for compartmentalization like keeping shopping and business confined to one and goat pron to another). The Tines had the only good pics but their artsy staff hallucinated that presentation was cool or something. Next time I'll just post the pics and leave the link at the bottom.

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  11. #8
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    Re: Stud welding and the Mexico bridge collapse

    [QUOTE=Welder Dave;8816733]T Would have been cool to see how the huge girders were straightened.

    probabaly not near the severity ur talkin about, but w/ this and the talk of trucks hitting bridges - figured id post it.


    https://weldingweb.com/vbb/threads/4...=bridge+impact

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  13. #9
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    Re: Stud welding and the Mexico bridge collapse

    Reading one of the articles it says sometimes the beams will go back straight on their own as long as the deflection isn't too much. Heat straightening is an art. Like in the old post above, having the right people is the key.

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