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RE: Plwd: Rigid Diaphragm Analysis - Opinions Wanted

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The simplified method is exactly the same as the normal method except
that the following requirements not not be checked or preformed:

SECTION 1630.1.2:	Modeling Requirements
SECTION 1630.1.3:	P-Delta Effects
SECTION 1630.2.1:	Design Base Shear (non-simplified) (still
applies w/ simplified force)
SECTION 1630.2.2:	Structure Period
SECTION 1630.5:	Vertical Distribution of Force (non-simplified) (still
applies w/ simplified force)
SECTION 1630.9:	Drift
SECTION 1630.10:	Story Drift Limitations
SECTION 1631:		Dynamic Analysis
and the Maximum Inelastic Drift (Delta M) shall be equal to .01*Story

That's it. All other stuff still applies like redundancy, overstrength
for collector design, and you design for 20% higher forces. I feel that
if you design your buildings for a 20% higher force and your competitors
spend an extra day or two doing calcs, your clients will gradually go
elsewhere. I feel that engineering fees are nothing compared to
construction costs. I recommend (not that I'm some authority) to do the
extra calcs, save your client some money, and you'll also know the code
a little better. If your buildings cost 20% more than the competition,
you'll lose.

My 2 cents

Gerard Madden
CRJ Associates
Design Engineer, Structural Department

> -----Original Message-----
> From:	Bill Allen [SMTP:Bill(--nospam--at)]
> Sent:	Tuesday, July 13, 1999 10:57 AM
> To:	seaint(--nospam--at)
> Subject:	RE: Plwd: Rigid Diaphragm Analysis - Opinions Wanted
> Off topic but relevant (to me, anyway).
> When using the Simplified Static Procedure, where in the code does it
> say
> that you do not have to calculate Rho or Omega?
> Under section 1630.2.3.4 Applicability (of the simplified static
> method), it
> says that sections 1630.1.2, 1630.1.3, etc. shall not apply but it
> does not
> say that section 1630.1.1 does not apply. Section 1630.1.1 is the
> section
> where Rho and Omega are defined and specified in E=Rho*E sub h + E sub
> v and
> E sub m = Omega sub 0 * E sub h.
> Is there another section that voids 1630.1.1?
> From what I've read, the only things that the simplified static method
> saves
> is looking at the fault maps to determine Na and the vertical
> redistribution
> calculation.
> TIA,
> Bill Allen, S.E.
> Laguna Niguel, CA
> <snip>
> >It seems that the only simplified approach suggested in the
> >code is for the
> >calculation of Rho and Omega such as in a residence where it
> >is not required
> >unless you are dealing with mixed structural systems or
> >transfering shear
> >from a wall to a frame or columns below.
> <snip>