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O/T: Cranes falling over. New construction falling over.

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  • #31
    Originally posted by old mart View Post
    I thought all modern cranes had computerised load sensing coupled to the reach and angle of their jibs.
    They do, thats why I thought it was operator error. Then again the crane in Cali looked pretty old. So even if it originally had load sensors what it they were in disrepair.

    And thats why I brought up regulations and inspections from local agencies. Not for that NO building crash.

    What if the cause comes back to the cement yard that made the concrete. Add a lil dirty water from the brackish river and see what happens.

    Spiff ballin. JR

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    • #32
      I think one factor is the modern trend towards allowing industries to "self inspect".

      Odd how often we find that the "self inspections" consisted of some guy sitting in an office checking off boxes without even bothering to go look.

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      • #33
        Probably some things in common with the Boeing 737MAX tragedies and the FSU bridge collapse, and other similar disasters, like the dive boat fire in WA. Seems like things have gotten worse lately, but there was a lot of corruption and many accidents involved with the Brooklyn Bridge 140 years ago:

        https://www.brighthubengineering.com...ooklyn-bridge/

        https://www.thoughtco.com/building-t...bridge-1773695
        http://pauleschoen.com/pix/PM08_P76_P54.png
        Paul , P S Technology, Inc. and MrTibbs
        USA Maryland 21030

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        • #34
          Originally posted by JRouche View Post
          They do, thats why I thought it was operator error. Then again the crane in Cali looked pretty old. So even if it originally had load sensors what it they were in disrepair.

          And thats why I brought up regulations and inspections from local agencies. Not for that NO building crash.

          What if the cause comes back to the cement yard that made the concrete. Add a lil dirty water from the brackish river and see what happens.

          Spiff ballin. JR
          Sensors or not the information that is usually lacking would be an accurate weight of the object being lifted and the effective sail force while it's airborne. Still operator error if he didn't get an accurate weight on the pole before the lift.
          I just need one more tool,just one!

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          • #35
            Regarding piles, here's an interesting (but slow) demolition video resulting from inadequate pile foundations: https://www.youtube.com/watch?v=y0zArm4FR1Y

            The wikipedia article curiously glosses over the piling problem: https://en.wikipedia.org/wiki/Ocean_Tower

            There's a blog about the lawsuit ( https://texasgeotechnicalengineer.bl...implosion.html ).

            Millenium Tower in SF is tilting as well. They went with 60-90' piles on a 600' building in an earthquake zone. The developer is trying to blame it on dewatering for an adjacent project, but they could have driven piles to bedrock 200-250' down. That's the proposed fix. https://en.wikipedia.org/wiki/Millen...San_Francisco)

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            • #36
              Originally posted by Dan_the_Chemist View Post
              I think one factor is the modern trend towards allowing industries to "self inspect".

              Odd how often we find that the "self inspections" consisted of some guy sitting in an office checking off boxes without even bothering to go look.
              One other aspect is that if the answer came out of a computer "it must be right!".

              Our young people are not being taught to analyze all of the input parameters and assumptions made. This applies to engineering design, climate science, ...

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              • #37
                An idea hit me this morning, in the drone video the opening scene is of the top floor. We can see in the video that work was being done there, particularly steel erection given that the crane is chokered off to a section of beam that is partially connected on one end,but not on the other.

                Another thing that becomes obvious is they have a lot of heavy stuff landed around that work area. Several stacks of steel stairwell sections, several pallets of concrete blocks, a couple steel skips one of which is loaded, and there was also a scissor lift working there that ended up on the rubble below.

                What are the chances they simply exceeded the load bearing limits of the floor with all the junk they had staged up there?

                https://www.youtube.com/watch?v=ZP4t...ature=youtu.be
                I just need one more tool,just one!

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                • #38
                  An update https://www.fox8live.com/2020/02/19/...ck-hotel-site/

                  FOX 8 received the records from the city Feb. 11 and has been analyzing the data and matching vehicles with potential drivers since the city said the software does not track which employee drives which vehicle. The GPS records revealed inspector Julie Tweeter may not have been able to inspect the Hard Rock Hotel construction site on at least four occasions last year. She claimed she did the inspections on an inspection log obtained by FOX 8 News. On July 18, 2019, Tweeter claimed to inspect the hotel site, passing contractors on a slab inspection. But according to GPS information for the vehicle believed to have been used by Tweeter shows she was not at the site. Those same GPS records show she spent one hour and forty-five minutes at her house during the middle of the day, but never at the Hard Rock site.

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                  • #39
                    I was in construction for 40 yrs and the trend the industry is going comes down to time and money. The customers want everything yesterday so they can start making money, the general contractors gladly oblige and put the squeeze on the subcontractors to speed things up by making unreasonable scheduling demands. This puts the sub in a position where they have to put more men on the job than planned for, or put in unplanned OT, or be penalized for missing deadlines or rush so much critical things are missed or purposely cut corners, all of which can cause these types of accidents.

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                    • #40
                      Originally posted by wierdscience View Post

                      Oh,you mean this one?

                      https://www.foxla.com/video/612772

                      Looks like the crane's outrigger found a storm drain, should have used mats/cribbing.
                      Doesn't look like that at all. Its quite clear that the whole crane pivots about the outriggers which are fully extended and not sunk into the ground as the crane goes over.
                      I'm surprised at this, for quite a few years big mobile cranes have had sensing equipment which will shut down the lift when it senses an overload situation developing. Assumes of course the equipment was working.

                      Even in my stoneage times with old crawler cranes we had the Wylie overload gear which rang a bell in the cab with an overload.
                      'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

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                      • #41
                        Certainly lots of question there- my first thought was why did they have to hoist the pole up so high- were they planning to drop it from a height so it would punch itself into the ground? Another thought I had was that given the capacity of the crane, that pole should have been an easy hoist. Then I wondered whether there was supposed to be a counter weight deployed opposite the direction the crane was leaning. It does appear that the truck had its outriggers deployed on solid ground- I couldn't detect a shift in them, even as the whole truck came off the ground. Perhaps they could, and should have been deployed further out? And what about weather conditions- did a wind come up and essentially push the whole thing over?

                        As far as the building collapse- well I'm not a papered engineer, but my first thought was that the structural support columns look pretty thin. I suggest that they were probably strong enough, as otherwise the bottom would likely have collapsed first, which didn't happen. I can't tell from the videos what part broke first, but it's certainly possible that the concrete was either sub-standard or they didn't give it enough setting time, or they weakened it by accelerating the cure too much.
                        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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