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Re: Bridge/building

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Michael,

Thanks for your thoughts.  I am sorry that my questions give you that
impression of me - that I should stick to mezzanines.  I guess I will have
to be more careful about the questions I ask.  I have certainly already
assumed that the geotechnical investigation would reveal that deep
foundations would be required in our area of high sinkhole activity and I
was also assuming large trusses or arches.  I have done plenty of mezzanines
too (although none of them seem to be mezzanines anymore - the architect
always turns them into second floors) but it is always nice to see something
unique thrown out there.  We do a lot of heavy industrial work, so we see a
significant number of unique (and massive) structures.  Without a heavy tall
silo out in the middle of the span, this should be a piece of cake.  (just
kidding - sort of)

I seriously doubt it will actually turn into a real project, but it is fun
to think about how to do it.  If it does move forward, I will certainly be
enlisting the assistance of a bridge design firm.

Just out of curiosity, why do you think that many very well qualified bridge
engineers would think twice about taking on a 500' span bridge - or are you
talking about bridge engineers who do everyday standard DOT 20' to 100'
boring precast concrete bridges that are already basically designed for them
by the precast concrete manufacturers?  That would not surprise me if such
an engineer - who does not think outside the box of standards - would be
afraid of this.  I would think that if I considered myself a very well
qualified bridge engineer (which I do not), I would love to have the
opportunity to work on a project like this.

Thanks for the leads on the other structures.  I wonder why they thought
they needed a post office over the railroad tracks.  Sounds interesting - I
hope I can find both of them.

Best regards,


Ken

Kenneth S. Peoples, P. E.
LVTA
Lehigh Valley Technical Associates, Inc.
1584 Weaversville Road
Northampton, PA 18067

Phone: 610-262-6345
Fax:610-262-8188
Email: kpeoples(--nospam--at)lvta.net

----- Original Message ----- 
From: "Michael L. Hemstad" <hemstad.ml(--nospam--at)tkda.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Wednesday, July 20, 2005 3:50 PM
Subject: Bridge/building


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33                               Message:0033
33
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From: Jim Wilson <wilsonengineers(--nospam--at)yahoo.com>
Subject: Re: Bridge/building
To: seaint(--nospam--at)seaint.org

Ken,

How does the cost of a bridge designed for full
vehicular loadings + the cost of the buildings work
out?  The differential cost for the buildings not
having foundations could compensate for some
aggravation factor.

Jim Wilson
------------------------------------------------------------------------
---
--- Ken Peoples <kspeoples(--nospam--at)lvta.net> wrote:

> We have a client who would like some rough ball park
> cost figures for a bridge/structure over a river.
> The bridge is not for vehicles, but for pedestrian
> traffic and shops/restaurant.
------------------------------------------------------------------------
----

From: "sscholl2(--nospam--at)juno.com" <sscholl2(--nospam--at)juno.com>
To: seaint(--nospam--at)seaint.org
Subject: Re: Bridge/building


"light truck traffic" to a restaurant is not light.

The Coke delivery trucks are about as heavy as they come- perhaps
lighter than a ready-mix truck but not much. One broke through the Santa
Monica Pier about 15 yrs. ago.

Stan Scholl, P.E.
Laguna Beach, CA

------------------------------------------------------------------------
------
OK, my turn.  I think everyone is missing some major points here.  First
of all, trucks are still lighter than pedestrian loading.  Even Coke
trucks.  Their concentrated wheel loads are huge, but on a square foot
basis they're not as heavy as a lot of people standing close together.

Next, buildings are designed with a floor live load, plus there's the
weight of the building itself.  If some of the buildings qualify as
"places of public assembbly," the live load alone is the same as a
pedestrian live load.  So buildings are probably heavier than either
trucks or people.

And you don't save the cost of the foundations.  You still have
foundations.  They're just 250 feet north of where the load is.

Ken, if I was drinking with someone and they asked me that question, I
would guess anywhere from 500 dollars a square foot on up, just for the
bridge.  At 2000 feet x 100 feet, that's 100 million dollars at best.
Pricey real estate.  There is a bridge over I-90 west of Chicago with a
McDonalds rest stop on it; there's a US Post Office somewhere (New York,
I think) built over railroad tracks with 10 foot deep plate girders.
Maybe you can track them down.

Finally, I have to tell you--you seem to look at a lot of projects
which, judging by the questions you ask, you are only barely qualified
to do at best.  What is your criteria for rejecting a project?  A bridge
with spans of 500 feet is something a lot of very well qualified bridge
engineers would think twice about taking on.  You're way outside of the
range of beams.  A bridge like that wants huge trusses, arches, or (God
help you) some kind of cable suspension system.  You can't even begin to
think about something like this without detailed geotechnical
information; bad soils could easily double the cost of such a project.

My advice, and I don't intend this to be belittling because I do a lot
of them, is to go find a nice mezzanine to design.

Michael Hemstad, P.E.
Saint Paul, Minnesota



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