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RE: (E) Masonry with steel upgrade

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I asked for your definition because your original post indicated that the
factor (omega) was 3.8; all of the omega values in the 1997 UBC are either
2.2 or 2.8.

Because you are in zone 4, the NEHRP Provisions would not allow the use of
detailed plain masonry shear walls.  In terms of intermediate behavior
(between RM and URM), FEMA 273 won't help you.  It too has a step function
at the reinforcement ratios you have previously reported.  However, you
could use FEMA 273 (in which case the system is classified as unreinforced)
and check your elements as force-controlled.  In other words, FEMA 273 does
allow excess strength to take the place of ductile detailing (within
limits).

************
> -----Original Message-----
> From: merrick group [mailto:merrickgroup(--nospam--at)compuserve.com]
> Sent: Friday, January 21, 2000 3:38 PM
> To: INTERNET:seaint(--nospam--at)seaint.org
> Subject: RE: (E) Masonry with steel upgrade
>
>
> Message text written by INTERNET:seaint(--nospam--at)seaint.org
> >seismic-force-amplification<
>
> seismic-force-amplification  OMEGA  gives a reasonable approximation of
> actual
> forces acting in an inelastically responding structure. EQ forces are
> required
> to be increased by this amount for teh design of elements ie collectors
> that
> should not yield. the Elastic response force is about 2xOMEGA
>
> My masonry wall in zone 4
>
> David Merrick, SE