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Re: FW: dynamic lateral force procedure

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Well said. We use static analysis every day.

Stan Scholl, P.E.
Laguna Beach, CA

On Tue, 11 Dec 2001 07:23:27 +1000 "T. Eric Gillham PE"
<teric(--nospam--at)gk2guam.com> writes:
> 
> OK, I'll weigh in with an IMO:
> 
> The attitude that more complex dynamic analyses utilizing faster and 
> better
> computers is the inescapable wave of the future for our profession 
> is IMO
> misguided and shortsighted.
> 
> Misguided because in the end it places more faith in a computer, and 
> a
> program written by someone else whom the designer probably hasn't 
> met and
> who they are basically relying upon to produce a safe and economical 
> design.
> FEM programs are too the point where even if the programmer provided 
> the
> code, it would be impractical to even attempt to check it --> the 
> "black
> box" scenario.
> 
> Shortsighted because it lends momentum to a cycle of having to use a
> computer driven dynamic analysis because the building is too complex 
> to do
> using a static procedure, after which the architect says "well, they 
> handled
> that one, so the next one can be even MORE complex", and so on and 
> so on.
> And no, I don't think that architects are evil, just that they will 
> push to
> satisfy their needs, just like everyone else, unless an opposing 
> force
> resists them.
> 
> I strive to work with my clients to REDUCE the complexity of the 
> STRUCTURAL
> system so that I am not forced to use a dynamic analysis.  In my 
> experience
> it is quite possible to create a simple, symetrical structural 
> system that
> is rational and can be understood, then hide it with architectural 
> elements
> that create the effect the architect desires - everyone is happy.
> 
> The problem that I see with the trend towards "throw more computer 
> power at
> it" is that the designer soon gets to the point where checking the 
> design,
> and fully understanding it, is next to impossible.  Sure, one can 
> still to a
> base shear check for equilibrium, but the mechanism formation for 
> the biggie
> earthquake is a toss-up.
> 
> Besides, even today most analysis programs are still ELASTIC, and as 
> we all
> know, most of our designs are done with INELASTIC mechanisms in 
> mind.  There
> are inelastic analysis programs out there and I have used them 
> (mainly for
> checking older, existing structures), but the application WRT a new 
> design
> is limited, IMO, unless it is for a final check.
> 
> On the other hand, maybe it's because I enjoy being able to put down 
> on
> paper, with a reasonable degree of certainty, just how the 
> mechanisms are
> likely to form. If that is the case, then it is probably just hubris 
> on my
> part - but I'll continue to do it :)
> 
> My to cents.
> 
> 
> T. Eric R. Gillham PE
> PO Box 3207 Hagatna, Guam 96932
> Ph:   (671) 477-9224
> Fax: (671) 477-3456
> Cel  (671) 687-7115
> 
> teric(--nospam--at)gk2guam.com <mailto:eteric(--nospam--at)gk2guam.com>
> 
> 
> -----Original Message-----
> From: Bob Ross [mailto:bob.ross(--nospam--at)wgint.com]
> Sent: Tuesday, December 11, 2001 4:48 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: dynamic lateral force procedure
> 
> 
> It is not possible to analyze and design for seismic using the older
> static methods. They no longer apply. The 3D, three dimensional 
> dynamic
> analysis and design methods must be used now, today. They are
> available. The computer software allows the practical application.
> 
> Quo Vadis?
> Pax e Gratia
> Bob Ross
> Robert P. Ross, P.E.
> Principal Project Manager
> Washington Group International,Inc.
> Industrial Processes
> 17320 Red Hill, Suite 300
> Irvine, Ca. 92614
> Mobile 562-254-4604
> Office 949-222-3978
> FAX 949-222-3985
> E-mail: Bob.Ross(--nospam--at)WGINT.com
> 
> ----- Original Message -----
> From: David Adie <dadie(--nospam--at)bjginc.com>
> Date: Monday, December 10, 2001 10:00 am
> Subject: dynamic lateral force procedure
> 
> > this survey / question is for those individuals who typically have
> > a choice
> > between designing their structures (buildings) with the dynamic
> > procedureand with the static procedure, and then choose to use the
> > dynamic procedure.
> > (ubc specific?)
> >
> > what subtle (or hidden) advantages are there?  do those advantages
> > outweighthe PERCEIVED increase in calculations / complexity?
> >
> > tia
> > da (static procedure guy, so far)
> >
> >
> >
> >
> >
> >
> >
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