Need a book? Engineering books recommendations...

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

Re: Need some URM advice -Reply

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Thanks Tim,
I believe that this is what I needed. The maximum capacity that I can assume
under special proceedure is 225 plf. I plan to install the plywood directly
to the joists since the roof is being reconstructed after demo of dry rotted
trusses. I want to keep the diaphragm as flexible as I can so as not to
impose too much shear into the URM walls, but stiff enough to span a greater
distance to avoid crosswalls where necessary (or at least minimize them).
BTW, it appears as though the 97 code has not changed at all from the 91
UCBC. 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

-----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
>
>
>