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Re: It's What You Don't Know That Hurts You...

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     In any situation, the fewer members there are, the larger they are.  This gives us more area to distribute prestressing forces.  Since the tendons were tensioned to 80% of yield, that leaves 20% to apply on the larger area.  It would be worthwhile to do the calcs to see what the unit stresses came to.  They may be acceptable.

Greg

-----Original Message-----
From: Bill Polhemus <bpolhem(--nospam--at)swbell.net>
To: seaint(--nospam--at)seaint.org <seaint(--nospam--at)seaint.org>
Date: Tuesday, September 19, 2000 8:37 AM
Subject: It's What You Don't Know That Hurts You...


>I'm just have to gripe a little bit here.
>
>I was informed by a colleague familiar with the situation that a bridge that had
>been designed under my supervision a few years back, which is being constructed
>now, has had some problems in construction.
>
>At the time of its design, I had a group of ten engineers working under my
>supervision at a consulting firm. Two of the "engineers" were recent graduates,
>but the rest either had or would soon have their P.E. licenses. We had this
>bridge project, which consisted of six bridges of various types, spans and
>configurations, part of a freeway expansion project. I divided my group into
>task forces with a P.E. as "project engineer" over each, and a senior P.E. as
>"quality assurance" (i.e. he was to check all design calculations).
>
>As it turns out, one of the bridges under a particular "project engineer" has
>had problems almost from the start, but the problems were rather minor in scope.
>However, this time, the problem is great.
>
>It seems that in designing the bridge to use prestressed concrete "U-Beams"
>(that is, they are a "U" shaped section), the design team had dithered about how
>many beams to use in each two lane span. They apparently settled on three beams
>per span. But unfortunately, somehow they had placed on the drawings, the
>prestressing information that was adequate if they had used FOUR beams. In other
>words, the prestressed concrete beams were underreinforced for the loading!
>
>Somehow, this got through not ONLY the design, but even the checking phase. The
>calculations exist that show the original project engineer's and the checker's
>initials. And of course, in the end I sealed the drawings.
>
>Now, it looks like the contractor is going to backcharge the client about $4
>million for the prestressed beams that are now, in a word, useless. They are in
>addition going to have to delay the project because they will have to have new
>beams made.
>
>I have not been contacted officially on this, and don't know that I will, but I
>am sure that this will be remembered by many in our area should the time come
>that I am in the running to get some of this kind of design work.
>
>It is frustrating to me because of the way that work is done in consulting firms
>like this, where you are SUPERVISING people who are doing the work, but the
>scope of the projects makes it difficult to be involved in every aspect of the
>design. I have found from time to time, in fact most recently just a few months
>ago, that if I DO get involved in detailed checking of others' work that is
>being done under my seal, I am very often disappointed.
>
>This, however, is the first time that a catastrophe of this magnitude has
>occurred, and I am sick about it! I pride myself on my diligence. We are all
>human, and prone to make mistakes, but the nature of the negligence on this
>project astounds me! I don't understand why others don't worry as I do about
>their work.
>
>I am now in private practice, and thankful that from this time forth nothing is
>going out under my name that I have not PERSONALLY been responsible for doing. I
>will never again trust the "QA" portion of the work to anyone else when
>something is being done under my supervision. I only hope that this particular
>chicken doesn't come home to roost directly over my head, but if it does I am
>resigned to take responsibility for it. H*ll, I guess I could lose my license
>over something like this. Not a good thing.
>
>Just a cautionary note to you all. Please be careful what is being done under
>your supervision.
>
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