Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Moving Walkway Seismic Restraint

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Daniel,

I have a Master's Degree in Mechanical Engineering, and I can tell you
that I never learned about lateral forces until I started working in
the structural engineering field.

My guess is that they just don't understand what it is you're talking
about.  It seems to me that the highest priority is just being sure
that the project gets designed safely - and I think the way to make
that happen is to educate the manufacturer on seismic design and then
work with them to figure out what type of anchorage is needed to make
it safe in an earthquake.  Ideally, they'll come back to you to tell
them what needs to be done.

Chris

On Feb 12, 2008 4:34 PM, Daniel Popp <drp181(--nospam--at)yahoo.com> wrote:
>
> An update:  the walkway manufacturer has provided a "total horizontal force"
> of roughly 1500 lbs, which I am hesitant to accept as ASCE 7 gives a load of
> approximately 50 kips.  As I have stated previously, the supports are steel
> shim stacks and wood blocks, which have little to no lateral capacity.  So I
> still have two problems: the difference in expected force level and the lack
> of a load path.
>
> In regards to Daryl's suggestion:  the "building official" in this case is
> the state government, as this is an airport project.  We have already
> planned to send them the letter from the manufacturer specifying no lateral
> forces -- we counted on it raising red flags with the structural reviewer.
> Now that we have been given loads, it becomes more tricky, as we are put in
> a position of questioning a mechanical engineer's calculations using a code
> that we do not have.
>
> Speaking of which:  if anyone has access to the ASME A17.1 code (2000
> version or newer), I would appreciate an excerpt from the seismic force
> section (8.5, I believe).
>
> Daniel
>
>
> ----- Original Message ----
> From: Benjamin Maxwell <enginerd666(--nospam--at)yahoo.com>
> To: seaint(--nospam--at)seaint.org
>
> Sent: Tuesday, February 12, 2008 11:15:49 AM
> Subject: Re: Moving Walkway Seismic Restraint
>
>
> I agree with Daryl, but I would also discuss options with the project
> architect (or whoever is the prime consultant), as well as with the owner in
> direct meetings to let them know what your problems are prior to blowing the
> whistle.  Also, get the issue on paper and distribute letters for your
> records.
>
> -Ben Maxwell
>
> Daryl Richardson <h.d.richardson(--nospam--at)shaw.ca> wrote:
>
> Daniel,
>
>         I would suggest that you take this problem to the building
> authority.  Once they find that they can not get an occupancy permit for the
> project they will probably come around to your way of thinking.  And quite
> fast, too!!
>
>         Mind you, this is a pretty potent weapon.  You may want to use it
> with discretion.  It can cause bad feelings with more than just the movable
> floor subcontractor.
>
> Regards,
>
> H. Daryl Richardson
>
> ----- Original Message -----
> From: Daniel Popp
> To: seaint(--nospam--at)seaint.org
> Sent: Tuesday, February 12, 2008 10:56 AM
> Subject: Re: Moving Walkway Seismic Restraint
>
>
>
> Ben,
>
> Thanks for your response.  The manufacturer is designing the anchorage;
> however, they are designing it for no lateral force.  Their "anchorage"
> consists of a stack of steel shims and a wood block.  They do know that we
> are in a fairly high seismic zone, but insist that their structure floats.
> Which of course it will, until it collides with our structure.  Then we will
> have a 50 kip force (plus impact) at unknown locations.
>
> The latest development:  we have asked that their letter be stamped by a
> structural engineer with a local license.  They are refusing.
>
> Any thoughts are appreciated.  We will be preparing a summary of the
> IBC/ASCE 7 requirements to demonstrate the magnitude of the forces involved,
> although this may not help.
>
> Regards,
> Daniel
>
>
> ----- Original Message ----
> From: Benjamin Maxwell <enginerd666(--nospam--at)yahoo.com>
> To: seaint(--nospam--at)seaint.org
> Sent: Monday, February 11, 2008 7:34:45 PM
> Subject: Re: Moving Walkway Seismic Restraint
>
>
> Daniel,
>
> Maybe they don't know you are talking about lateral load due to a seismic
> event.  Sounds stupid, and possibly insulting, but you never know.  Unless
> this thing uses George Jetson technology, you're going to have a seismic
> load to content with.  You should get that letter from them first though and
> then put it on the internet.  I'd love to see that one.  Good comedy there.
> ;-P
>
> On a serious note -
>
> One way around having to extract information out of vendors who don't really
> know what the heck you want is to simply ask them for diagrams of the dead
> and live loads and an anchorage plan.  They can usually do that pretty
> readily. Then you can figure out what you need to from there.
>
> Are you designing the anchorage of the equipment to the structure, or is
> this to be designed by the vendor?  Do they know they need to anchor their
> equipment to the structure to meet the requirements of the building code
> (assuming IBC-based code)?
>
> -Ben Maxwell
>
>
>
> Daniel Popp <drp181(--nospam--at)yahoo.com> wrote:
>
>
> A current project of ours incorporates a moving walkway on a pedestrian
> bridge.  The project is at the high end of Seismic Design Category C and
> thus seismic forces are substantial.  However, the moving walkway
> manufacturer insists that the walkway will impart no lateral load to our
> supporting steel structure.  They are willing to put this in writing, but I
> am not comfortable with a 63,000 pound piece of equipment sitting on my
> structure without a defined seismic load path.  Calculations using the
> non-building sections of ASCE 7 indicate lateral forces on the order of 50
> kips, which is quite different from zero.
>
> Does anyone have any experience with moving walkway installations?  I am
> particularly interested to know if anyone has received horizontal (seismic)
> reactions for such a walkway, particularly in California or other
> high-seismic areas.  Any suggestions on how to extract this information from
> the manufacturer would also be appreciated.
>
> Thanks,
> Daniel R Popp, S.E.
>
>
>
> Benjamin H. Maxwell, S.E.
>  ________________________________
>  Never miss a thing. Make Yahoo your homepage.
>
>
>
> Benjamin H. Maxwell, S.E.
>
>  ________________________________
> Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it
> now.
>

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********