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Re: deck collapse

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Attention  ALL:



Please  check  the SEAOI  website

www.seaoi.org

for a statement of the Deck Collapse
(should be in a pop-up window)


Bob Johnson, SEAOI

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


In a message dated 7/2/2003 7:23:48 PM Eastern Standard Time, dennis.wish(--nospam--at)verizon.net writes:

> 
>   Subj:  RE: deck collapse
>   Date:  7/2/2003 7:23:48 PM Eastern Standard Time
>   From:  "Dennis Wish" <dennis.wish(--nospam--at)verizon.net>
>   To:  <seaint(--nospam--at)seaint.org>
>   Reply-To:  <seaint(--nospam--at)seaint.org>
>   Sent from the Internet (Details)
> 
> 
> 
> 
> I appreciate Roger's comments. We live in an era where information comes
> immediately and not incompletely. We jump the gun too often and have not
> learned to collect information, disregard speculation and stop thinking
> that there is a conspiracy under every stone. 
> How often do we find solutions to problems come from walking away and
> getting our mind off the facts for a while. It cleans out the garbage
> and the cobwebs and allows us to approach a problem from a new
> perspective.
> I've often solved problems while guitar playing, or sitting in a bathtub
> or driving in a car. To sit and stare at the pictures does not resolve
> an issue, but understand why the materials behaved the way they did
> prior to the collapse is most important. It was reported that the
> balcony swayed before collapsing and this might be important if the
> movement was in time to music the students were listening to and their
> movement was contributing to the lateral movement of the non-laterally
> support columns at the outside face of the balcony. Remember where this
> occurred - in a Zero Zone for seismic activity on an open structure
> generally unaffected by wind loads (except for uplift) with columns that
> might be allowed to sway and the only lateral restraint contributing to
> the balcony being the stair stringer connected (or not) at the concrete
> level.
> 
> With all of this said, we don't even know yet whether the stairs were
> permitted or not OR if the stairs might have been included in the
> overall remodel permit.
> 
> I think that it was a tragic accident that can be avoided or reduced (I
> can't remember the last time this happened in Chicago) by posting the
> limit of the number of people that can safely use the balcony at one
> time. Load Limits mean nothing to the public but posting a limit by the
> number of people on the balcony may be more effective.
> 
> Dennis Wish PE
> 
> 
> -----Original Message-----
> From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com] 
> Sent: Wednesday, July 02, 2003 3:01 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: deck collapse
> 
> 
> Scott,
> 
> Throughout your post, you refer to, "they."  I don't know who "they"
> are.
> 
> The deck collapsed just after midnight on Sunday morning and was
> demolished 
> by 6:00 p.m. Sunday afternoon.  There are not very many structural
> engineers 
> that are available around the clock to be called out on a moment's
> notice.
> 
> I am assuming that W-J-E was on contract with the City of Chicago to 
> investigate situations like this, and W-J-E is a highly respected and 
> reputable firm whom I expect will do an exemplary job.  However, 2 pairs
> of 
> eyes are better than one pair, and 4 pairs are better than 2 pair.  Was
> it 
> not a solitary California Structural Engineer (James F? whose name
> eludes me 
> right now) that pointed out that A490 bolts were misused in the Kansas
> City 
> arena roof collapse?
> 
> I can walk around sites for hours, asking why, why, why?  I can take
> roll 
> after roll of pictures, but if I don't take a picture of the right
> thing, all 
> those photos are meaningless.  For a single motor vehicle fatality,
> police 
> will shut down the road for hours until their investigators (plural)
> map, 
> measure and photograph the scene.  And after that the vehicles involved
> are 
> taken to an impound lot as evidence and for further investigation.
> 
> I have come to the conclusion that short of being grossly underdesigned,
> 
> everything that fails in the same manner is sympathetic failure; the one
> 
> element that fails in a completely different manner is probably the
> element 
> that failed first and caused the resultant collapse.  If one looks at
> the 
> elements that all failed in the same manner, it is easy to come to the 
> conclusion that the structure was overloaded, as overload is what causes
> 
> sympathetic failures.  But coming to that conclusion can cause one to 
> overlook what initiated the failure.
> 
> A. Roger Turk, P.E.(Structural)
> Tucson, Arizona
> 
> Scott Maxwell wrote:
> 
> . > Andrew,
> 
> . > I have heard on at least one news report the same thing that Chris .
> > said...they were unsure if a permit had been issued for the deck. . >
> According to the report that I saw, the building had been renovated in
> the . > recent past to convert it from 6 appartments to 3 (as Chris
> mentioned). . > There apparently was a permit for that work, but no one
> knew for sure . > whether or not that permit also covered the deck or if
> there was a . > seperate permit issued.
> 
> . > As to the issue of clearing away the rubble from the site...have you
> . > considered that make they were able to determine the cause of the
> collapse . > in that amount of time?  After all, you have made the
> determination that . > it cannot possibly be due to accidental
> circumstances (at least in your . > mind) but rather due to negligence
> by someone (the engineer, contractor, . > owner, etc) and you have been
> on the site for exactly ZERO seconds looking . > at the rubble.  My
> point (without the sarcasim now) is that it is entirely . > possible
> that they may have already gotten all the information that they . >
> needed to determine the cause of the collapse, thus it was perfectly OK
> to . > remove the debris so that people would not be inconvienved in
> getting in . > and out of their homes.  In otherwords, it is entirely
> possible that they . > had gotten all the information that they needed
> (i.e. photographs, etc) . > for their investigation.  After all, this
> was a rather small wood deck . > with no things like exterior cladding.
> Think of it in proportional . > sense...it took less that a year to
> clear away the debris from the WTC . > collapse and it was TWO 100+
> story buildings (with floor plans of . > several hundred feet by several
> hundred feet) with added debris from . > furnature, interior partitions,
> and exterior walls compared to the time . > for clearing away the debris
> for this collapse that was only a 20 . > something by 20 something foot
> deck (at least from what others have said). . > Thus, if you look at it
> from a proportional sense, then someone could make . > the arguement
> that if you consider the amount of time clearing away the . > debris at
> this incident then the time for the WTC was totally . > insufficient,
> yet I doubt that there is too many people that feel the . > debris at
> the WTC was cleared away too quickly.
> 
> . > This leads me to my suggestion...maybe we should try avoiding to . >
> conclusions without all the information in hand, eh?  After all, while I
> . > do believe that the lack of WMDs discovered in Iraq TO DATE raise
> some . > questions about the primary rationale that was advertised for
> the need for . > war, I also believe that anyone who wants to claim that
> Bush lied or . > twisted information is just an idiot who is jumping to
> conclusions.  The . > point is that we don't have enough information to
> make a make a conclusion . > on either the Iraq issue nor the cause of
> the collapse.  So, I would . > suggest a little patience before you get
> too hot under the collar about . > anything and get all the INFORMATION.
> 
> . > As to the structural issues at hand...you have focused on pure
> gravity . > live load issues.  Have you considered that the collapse may
> have occurred . > due to insufficient lateral resistance?  And I am not
> necessarily tallking . > about something sufficient enough to reist a
> significant earthquake.  At . > least one person on the list has
> mentioned eyewitness reports that stated . > that the deck was
> "swaying".  Thus, it is possible that the deck just . > swayed too much
> creating a significant P-delta "extra" load that then . > caused the
> live load to be "exceeded" even though there may not have been . >
> enough people present to exceed 60 psf.  Admittedly, such a possibility
> . > would still lead to a claim that the engineer (if there was one)
> should . > have accounted for this.  My point is that you seem to be
> "target locked" . > on how you believe that the engineer may have goofed
> which means that you . > could be potentially be doing the same thing
> that you seem to be accusing . > the person who designed the deck of
> doing...not looking at all the . > possibilities (although I could be
> wrong...you could have thought of such . > things yourself already).
> Thus, again, maybe we should wait a little be . > longer before we jump
> to conclusions.
> 
> . > HTH,
> 
> . > Scott
> . > Ypsilanti, MI
> 
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