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View Diary: The New SF Bay Bridge: Proof We Are Now a Banana Republic (163 comments)

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  •  Thank you for pointing that out. It is an (9+ / 0-)

    important aspect of the story (designers vs. builder).

    •  Well, and hanging peripherally around structural (8+ / 0-)

      engineers, I know T.Y. Lin has a good strong international reputation for structural design generally, and bridges specifically.  If the change in specified bolt types do not let the design perform as it should, it...may not.

      See the hotel skybridge collapse case in Kansas City with contractor substituting a structural support and assembly that the designers signed off on, and the resulting catastrophe:

      http://en.wikipedia.org/...

      I'm part of the "bedwetting bunch of website Democrat base people (DKos)." - Rush Limbaugh, 10/16/2012 Torture is Wrong! We live near W so you don't have to. Send love.

      by tom 47 on Fri Aug 23, 2013 at 10:15:10 AM PDT

      [ Parent ]

      •   The engineers submitted a bad design in KC (23+ / 0-)

        I am fairly expert in structural matters, being a design professional (architect).  At KC they designed a three story long hanger-rod, of which there is no such thing available, at least not as a special order.  The fabricators substituted two separate rods.  Instead of splicing the two rods into one co-linear rod, they changed the design detail to two separate rods in two different lines, mere inches apart.  This connection to the beam supporting the skywalk, which was a simple steel tube, was the fatal error.  One tube was pulling the tube up as it hung from the roof and supported the bridge the beam was actually intended to support- the other was pulling the tube down as the load of the bridge below was being transferred through the portion of the tube between rods.  In other words, the tube was being ripped apart by these two opposing up and down forces from the moment it was built.  (Shear is the structural definition- it sheared apart).  KC was a failure of everyone involved, contractor and designers, when the bad design was approved.

        As to the new bay bridge- I agree there is great concern based on what I have read on it, but there are also the ethical duties all of the engineers involved have to ensure safety,  they are bound to them by law.  So any potential for failure must fall within design allowances. My real concern is the bonuses for finishing by certain dates. I have never heard of this- only penalties for finishing late.  It's a really bad idea, and should probably be made illegal.  Things take a certain amount of time to build- rushing is always a bad idea.

        •  Liquidated Damages is pretty common (10+ / 0-)

          on major projects and as an incentive to get a General Contractor to sign on to the contract, the client usually offers bonuses for finishing early. This is popular on big project that have a history of blowing deadlines and blowing budgets. Millenium Park in Chicago and The Big Dig in Boston come to mind.

          That said, this isn't really a sign of a Banana Republic, it is a sign of a race to the bottom when it comes to paying for products and services. Clients don't understand the three legged stool concept anymore and feel that they can get things done cheaply and on time and still buy a quality product. One of the three legs will collapse.

          •  Better, faster, cheaper: Pick two. (4+ / 0-)

            This is a well known mantra in the Engineering profession.

            We also say, "In ten years, if it's right, no one will remember that it was late; and in ten years if it's wrong, no one will remember that it was on time."  This latter dictum, however, applies only to resisting managerial pressure to enforce deadlines; it does not address the issue of gold-diggers racing to the bottom.

            The hungry judges soon the sentence sign, And wretches hang, that jurymen may dine.

            by magnetics on Fri Aug 23, 2013 at 03:22:23 PM PDT

            [ Parent ]

        •  Yes. (7+ / 0-)
          As to the new bay bridge- I agree there is great concern based on what I have read on it, but there are also the ethical duties all of the engineers involved have to ensure safety,  they are bound to them by law.  So any potential for failure must fall within design allowances.
          I am a structural engineer.  I can reassure you that no licensed engineer is going to rush through an approval or put his seal on a drawing without being damned certain of its adequacy.  I'm not saying we never make mistakes, but what is being alleged here isn't a calculation error but systemic corner cutting.  Not going to happen on the engineer's part.

          In addition to the immense liability of a failure, there's also the small matter of keeping your license, which is necessary to your livelihood.  We do not jeopardize that; ever.

          I can't speak to the specifics of the A490 bolts in this case; but I feel confident that if they were approved after potential problems were identified, that those problems were properly examined and evaluated by a licensed engineer, and that their capacities carry an appropriate factor of safety.  Ultimately it comes down to a guy with a calculator and an AISC code book.  We know what we're doing; that's why we get the big bucks.  :-)

          You can't spell CRAZY without R-AZ.

          by rb608 on Fri Aug 23, 2013 at 12:30:55 PM PDT

          [ Parent ]

        •  I agree that some (11+ / 0-)

          of the responsibility needs to fall on the designer.

          I have quit projects in the design phase when I can see that the client is not respecting my opinion on serious safety issues or legal violations.  I always put my dissent in writing and if it is not listened to I'm out of there.

          A big problem with government projects is that they are almost all design-build, meaning that the A/E team is reduced to a bunch of grunts beholden to the contractor.  Decades ago, the client would hire both the architect and the contractor.  The architect would serve in the client's best interest as their advocate, to ensure that the contractor wasn't cutting corners.

          Contractors have a profit motive to cheat the client, while the architect's only profit motive is to serve the client.  Contractors have worked long and hard, and successfully, to remove the architect from the equation.  With design/build, they have free reign to say no to the architect and tell the client whatever they want.

          The design/build project delivery system has been a disaster not only for the A/E industry, but for the built environment in general.  I'm not 100% sure that the Bay Bridge was a design/build project, but in my experience with CA state and federal projects, they almost always are.

          "Mediocrity cannot know excellence." -- Sherlock Holmes

          by La Gitane on Fri Aug 23, 2013 at 12:34:26 PM PDT

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          •  Design build still requires an architect (2+ / 0-)
            Recommended by:
            La Gitane, BlueMississippi

            and engineer.

            •  Yes (3+ / 0-)
              Recommended by:
              Ray Pensador, NYFM, la urracca

              but in design/build they contract with the contractor, not the owner.

              Therefore they don't report directly to the owner, the contractor does.  The contractor has the last word on what gets presented to the owner.

              "Mediocrity cannot know excellence." -- Sherlock Holmes

              by La Gitane on Fri Aug 23, 2013 at 01:52:11 PM PDT

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              •  Design/build is a bad development for A/E's (4+ / 0-)

                I speak as someone who has defended design professionals since 1986.  The mindset of a GC and the mindset of an A/E are usually very different.  Design/build makes A/E's think more like GC's, which isn't a positive development.

                Some men see things as they are and ask why. I dream of things that never were and ask why not?

                by RFK Lives on Fri Aug 23, 2013 at 03:04:48 PM PDT

                [ Parent ]

                •  TOTALLY agree (6+ / 0-)

                  I find myself having to explain this to clients very often.

                  Contractors have a profit motive that isn't necessarily in the owner's best interest, and owners usually don't have enough experience in the building industry to know better.  The architect is the only knowledgeable advocate that the owner has - our motive is completely different from that of the GC.

                  Sort of a fox in the hen house situation....  thank you so much for speaking on this.  It's rare that this issue gets talked about!  My colleagues are all afraid to diss the GC's for fear of never getting any government contracts.

                  "Mediocrity cannot know excellence." -- Sherlock Holmes

                  by La Gitane on Fri Aug 23, 2013 at 03:24:39 PM PDT

                  [ Parent ]

        •  To clarify... (12+ / 0-)

          What happened in KC as a result of the design change was that the connection for the hanger at the upper walkway ended up carrying twice the load for which it was designed.  It wasn't a shear failure of the member in the technical sense; the nut supporting the cross member pulled through from the bottom.  

          As an aside, I have to say that collapse spooked me a little as an engineer.  The field modification proposed by the contractor looked so sensible and practical, I'm willing to bet more than one engineer would have missed the structural implication that ultimately resulted in collapse.  I know I'm a lot more cautious because of that.

          You can't spell CRAZY without R-AZ.

          by rb608 on Fri Aug 23, 2013 at 12:37:54 PM PDT

          [ Parent ]

          •  KC -- The switch from the traditional design (4+ / 0-)

            To the "new improved" design that led to the structure's complete failure was the subject of a Scientific American article (from some time back.)

            Why no one caught it, while still in design mode, I don't know. I guess the person that proposed the change possessed enough seniority or "expertise" that they were not questioned nor was the design examined - until after the hundreds of people died.

            Offer your heart some Joy every day of your life, and spread it along to others.

            by Truedelphi on Fri Aug 23, 2013 at 02:41:54 PM PDT

            [ Parent ]

          •  yes, corrections to my (and the wiki account) (4+ / 0-)

            I made a typo above, should be: One rod was pulling the tube up...
            and a factual error: the beams were not tubes but a pair of channels placed "toe to toe" to form a 'box'.  This is a tube shape and behaves similarly, although unlike a tube channels have flanges that actually taper and are smallest at their ends (the 'toe')- this is the point where they were welded together at KC to form the 'box'.  

            I think the wiki account makes an error in the details of the explanation for (mode of) the failure.  The welded pair of channels did have a resultant 'seam' on top and bottom, but the weld is not a weak point- welds are actually very strong.  It is normally a weak point because the channel's flanges are thinnest there.  If you look at the photo provided you see the webs of the channels were bent and deforming with the flanges pointed upward during failure.
            Now, it is also true that the failed channel-beams were overloaded due to their also carrying the load of the bridge below, in addition to the single bridge they were intended to.  This is true, but the channels actually performed without failing for over a year.  And I believe this indicated (and it was also calculated) that the channels would not have failed were they placed back to back instead of toe to toe- despite their having been doubly loaded.  So my understanding of the mode of failure was the general principle of shearing action on the flanges of the box shape.  The channel shapes "hinged" where the flange transitions to the web, and the web being thinner, it began bending up.  The nuts/washers only cracked because their bearing surface suddenly changed from one flat plane to two sloped planes which were also spreading apart.  The wiki photo shows not the 2nd floor support rod but the 4th floor to roof rod.  And as the wiki diagram shows the underside of the 4th floor beam where the rod went up to the roof was the point of double load.  If the seam/nut connection failed, the beams would have maintained their box shape while either the nut/washers punched through (sheared) the welded seam.  But they didn't.  The beams deformed and then the nuts failed.

            My understanding of KC is based on the ENR articles on it, and knowledge I acquired through one of the attorneys I know who actually worked on the litigation and settlements.

        •  wasn't that the one where the nuts failed? (5+ / 0-)

          Instead of a continuous rod with nuts at each level holding up a single level, they had separate rods which essentially put all of the levels load on the top nut? That was a real bozo error, as I recall. Not that it has anything to do with this situation. Hydrogen embrittlement is a fairly well-understood and age-old problem, I would be very surprised if the engineers tried to somehow sweep this under the rug. That would be criminal.

          •  See the link above. (3+ / 0-)
            Recommended by:
            Ray Pensador, akeitz, BlueMississippi

            I guess I was trying to point out the initial onus on the designer (engineer), the attempt to reduce costs by the constructor, and the failure of either/both to see the load and component implications.

            It looks like there is a similar situation for the Bay Bridge, though different in the particulars of the design and the demand being placed in the bolts.

            IANAE.  Thanks for those of you knowledgeable professionals who elaborated and added to the depth of the discussion. I knew my simplification would suss out you experts.  ;-)

            I'm part of the "bedwetting bunch of website Democrat base people (DKos)." - Rush Limbaugh, 10/16/2012 Torture is Wrong! We live near W so you don't have to. Send love.

            by tom 47 on Fri Aug 23, 2013 at 01:48:07 PM PDT

            [ Parent ]

        •  Engineers, as opposed to lawyers, are obligated (5+ / 0-)

          by oath to serve the interest of the public over the interests of their client.  Yes, the engineers should speak up and, if necessary, block progress to prevent a bad design from being constructed until the design is fixed.

          Gentlemen, you can't fight in here! This is the War Room!

          by bigtimecynic on Fri Aug 23, 2013 at 02:02:16 PM PDT

          [ Parent ]

    •  And why hasn't the diary been corrected? (1+ / 0-)
      Recommended by:
      BlueMississippi

      Ugh.  The whole thing bugs me.  Contrary to how the diarist presents it, there is nothing at all inherently unsafe with self-anchored suspension bridges.  They've been around since the early 1800s.  Of course engineers will have differences of opinions about designs in different situations, but as for the basic bridge design, there's nothing at all wrong with self-anchored suspension bridges.

      As for the bolts, since I'm not an expert on such things, I wouldn't feel comfortable offering my opinion on the topic.  But I can tell you that the use of high strength galvanized steel in bridges in general is also nothing even remotely new.  And the fact that it's been called out in the press as an issue means that the concept that they're just going to let the bolts get embrittled and not bother to keep track of it is pretty absurd.

      Já þýðir já. Nei þýðir nei. Hvað er svona erfitt við það?

      by Rei on Fri Aug 23, 2013 at 04:15:39 PM PDT

      [ Parent ]

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