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Re: Need some URM advice -Reply -Reply

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>>> "wish" <wish(--nospam--at)cwia.com> 01/09/98 01:10am >>>
" Can you tell me if there are any major changes to special procedure
that I should be aware of? Thanks for your help on this, Tim, I appreciate
it.
Regards
Dennis"

Dennis,
By looking in my "Analysis of Revisions to the 1994 Uniform Codes"
(ICBO), I see that the main change in the 1994 UCBC was the reduction
of the design base shear equation from coefficient from 0.33 to 0.25. The
scope also was enlarged to include adobe and stone masonry.  The
1997 UCBC adds structural observation as a requirement for buildings in
seismic zones 3 and 4. These are the only changes I see.

Regards,

Tim McCormick, P.E.
City of Los Angeles

-----Original Message-----
From: Tim McCormick <TMCCORMI(--nospam--at)BAS.CI.LA.CA.US>
To: seaoc(--nospam--at)seaoc.org <seaoc(--nospam--at)seaoc.org>
Date: Thursday, January 08, 1998 9:02 AM
Subject: Need some URM advice -Reply


>Dennis,
>
>>From Table A-1-E of the latest version (1997) of  UCBC Appendix 1-
>retrofit standard for URM bearing wall buildings:
>
> 1.1 Plywood sheathing nailed directly over existing straight sheathing
>with ends of plywood sheets bearing on joists or rafters and edges of
>plywood located on center of individual sheathing boards- 225 lbs. per
>foot (3283 N/m)
>
> 1.2 Plywood sheathing nailed directly over existing diagonal sheathing
>with ends of plywood sheets bearing on joists or rafters- 375 lbs. per
>foot (5473 N/m)
>
>1.3 Plywood sheathing nailed directly over existing straight or diagonal
>sheathing with ends of plywood sheets bearing on joists or rafters with
>edges of plywood located over new blocking and nailed to provide a
>minimum nail penetration into framing and blocking of 15/8 inches - 75
>percent of the values specified in Chapter 23 of the Building Code
>
>As a side note, the Los Angeles Division 88 has different standards for
>diaphragm capacity when used for strength or stiffness. The strength
>criteria uses the blocked diaphragms values of Table 23-1-J-1 while the
>stiffness check (DCR) uses a maximum of 225 pounds per foot. Note
that
>UCBC  Appendix 1 uses only 75% of the UBC values in Chapter 23. This
>is actually identical to LABC Division 88 because the LABC is actually
>75% of the UBC Chapter 23 values. UCBC Appendix 1 allows higher
>capacities in the DCR check. Also note that the "Special Procedure" is
>optional in the UCBC Appendix 1 while the DCR check of Division 88 is
>mandatory for all design methods.
>
>Tim McCormick. P.E.
>City of Los Angeles
>
>
>