Collapse Simulation

Collapse Simulation

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19 Responses to Collapse Simulation

  1. Christian J. Chuba says:

    Preventing a building from collapsing is always the first, second, and third best option.

    I think the rescue efforts could have been handled better, can’t prove it and it’s water under the bridge. If anyone ever has a loved on in that situation get in the guys face and ask which USAR (Urban Search and Rescue) groups are involved, how many people are on it.

    The UN is well organized for rescue efforts like this and has a registry.
    https://reliefweb.int/report/indonesia/how-rescue-people-trapped-collapsed-building
    https://vosocc.unocha.org/USAR_Directory/MemberCountriesOverview.asp

    We had one group from Mexico (no info on them) and 12 guys from Israel and one of them was always being interviewed. If you need outside help, there is more out there and they train for language barriers. Plus there is FEMA.

    Just scanning the USAR directory, both Turkey and France looked like they have good depth. Glad to see they are using our NATO free riding money on something useful.

  2. Deap says:

    Sad to say, but building both lives and buildings on solid bedrock in the lesson of the hour.

  3. Porkupine says:

    Col:
    I was talking about Deap’s “Sad to say,” but we
    must all cope with a lack of bedrock each in his, or her, own way.

    • Pat Lang says:

      Porkupine

      In 2009 I was a member of a team in an IQ2 debate on the question “Can we ever win in Afghanistan.” I argued strongly that we could not.

  4. Peter+VE says:

    On the NPR, they mentioned that all the rubble from the collapse was being brought to storage, so that NIST (National Institute of Standards and Technology) could do a thorough analysis of the reinforcing steel and the concrete.
    Why do I bring that up? By December 2001, 50,000 tons of the steel frame from WTC 1, WTC 2 and WTC 7 had already been shipped to China to be recycled. Of the 300,000 tons of steel in the 3 buildings, only a couple thousand tons were retained to be used in memorials The reports on the collapse of the 3 buildings were based only on computer simulations. Since WTC-7 is the only steel framed high rise to collapse from fire alone, perhaps NIST should have been interested in physical analysis of the steel. Perhaps….

  5. Porkupine says:

    Col. Lang
    I will look up that debate.

    Seems like these foreign policy people have
    delusions of grandeur, poor sense of history and geography.

    • Porkupine says:

      What do I know, but God loves defensible terrain.

      Early in the 2000’s an older housemate of mine who had a son in the marines
      or Army told me that this son (in Afghanistan) told him that
      the enemy didn’t stand a chance because
      of our tech (optics etc).

      C’mon, man!
      That just keeps our casualties low. Imo.

  6. William M Hatch says:

    We join a long list of proud empires that have run aground in Afghanistan. The Chinese may be wise enough to accept Afghanistan as it is & simply support the tribes that can help them, bribe those who need bribing & extract the minerals & rebuild their “Silk Road”. I don’t think that the Chinese will bother with nation building, human rights or civilizing the unruly Afghans.

    • Barbara Ann says:

      William M Hatch

      I suspect that is exactly what the Chinese will try and do. Chinese FP is notable for an absence of the ideological compulsion to try and turn foreign nations into replicas of their own. They have been talking to the Taliban as well as the Kabul government and although not an ideal choice, if a Taliban government would keep the TIP reigned in (a big “if”) the rewards by way of BRI could be very considerable. Pompeo removed TIP (called the East Turkestan Islamic Movement at the time I think) from the FTO list late last year – much to China’s consternation. It will be interesting to see if the “China Joe” administration reinstates them.

      A stable polity that can guarantee security is essential for trade, so the prospect of Afghanistan being “lost” to the US raises possibilities. I imagine there will be a spoiler lobby among the Borg who will be pushing hard for Afghanistan to be “denied” to the enemy. The Great Game will go on.

  7. Porkupine says:

    Col. Lang,
    I will look that up, thank-you.
    That should be entertaining.

  8. Ishmael Zechariah says:

    Interesting simulation. I wonder, though, what structural elements they used in the model. The collapse of this building reminds me of the pancaking of the sub-standard buildings during recent earthquakes in Turkey. Properly built high rises survived.
    Even the best concrete is weak in tension and shear; one uses primary and secondary reinforcement (ductile steel) to counter these forces. Based on the state of the rubble, it seems highly likely that both the concrete and the reinforcements in the columns were not to code. If they had steel rebar cages in all support columns with well integrated links and mesh wrap to the steel in the floor slabs, some pockets should have been left in the rubble, not the total pancake we see. They might have also used unwashed or badly washed sand in the concrete, accelerating corrosion of the reinforcement. Similar considerations apply to the floor slabs. I wonder what they will state in the final failure report. In Turkey a lot was swept under the carpet…
    Ishmael Zechariah

    • Barbara Ann says:

      IZ

      Modelling of structural failures is a specialized science (no djinn involved). Modern modelling techniques, including finite element analysis, can get right down to detail small enough to look at individual rebar failure or crack propagation, for example. This looks like a model designed to explain what actually happened on a large scale, including the collapse of a shear wall – one of the largest and most important structural elements of a building.

      The interesting thing about this model is that its hypothesis for the initial cause is an punch through failure by a column. This is not a failure of the column itself due to subsidence (e.g. due to a poor ground survey missing a sink hole) and that implies a failure of the reinforced concrete that ties the column-top into the floor slab. These things are designed to codes, as you describe, where a 4:1 safety ratio is normal – i.e. they are designed to withstand 4x the maximum expected load. This is one reason why you seldom see such catastrophic failures, which should be vanishingly rare in a first world country.

      A deterioration of the rebar or concrete itself such that a punch through is possible must imply gross (likely criminal) negligence in design, construction, maintenance, or some combination of the 3. Whatever the result of the investigation, this scale of disaster is the sort of thing that define future building codes.

      Disclaimer: I studied this stuff, but never put it into practice professionally. I defer to any professional structural engineering expertise present.

      • Mark Logan says:

        It’s a plausible theory but only that as yet. What’s heartbreaking about this scenario is how simple it would have been to place temporary shoring under that deck. That was a parking garage under there. Deck doesn’t drop and nothing happens.

        Ishmael, It would be surprising if somebody got away with not building to code on structural. Florida builds for hurricanes and accordingly, 40 years ago, had their own stricter US building code, the Southern Building Code (SBC) and a reputation of enforcement.

  9. akaPatience says:

    Seeing pre-collapse photos of garage areas which included rusty corrosion, pockmarked concrete walls, exposed rebar, and potholed driveways, it was obvious that maintenance was deficient. Why did affluent owners allow such conditions? Whether or not any of it led to the collapse doesn’t necessarily matter – even if just cosmetic, these conditions made it apparent that building maintenance was poor. I’m not certain if it’s true but I’ve read that some real estate brokers were even wary of going out on balconies during showings! Brokers have a responsibility to disclose building conditions to prospective buyers. No doubt there will be lawsuits aplenty.

    • Deap says:

      Buyers do have a duty to read the homeowners association governing documents and past five years of meeting minutes – the need for $9 million plus in structural repairs had been on the agenda for some time – I believe this worked out to $100K per owner as a special assessment. Hard to keep that secret when a buyer is conducting due diligence. Unfortunately this was not a matter of if, but when.

      The simulation was chilling. Much like the engineers knew on the Titanic – once a critical number of chambers flooded all hope was lost. Massive storied structures teetering on top garage pilings looks, to the layperson, to be so fragile in retrospect, but it is the nature of many buildings today – parking below and residential on top.

      Makes one wonder what Dubai (UAE) will be facing in a few more decades – with their sand and sea exposures, along with local construction codes and inspections in their infancy.

      How did the Romans know enough to build so many tall structure, still standing 2000 years later?

  10. ping says:

    Good stimulation from Mike the bell

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