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Re: FEMA 302

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I'm a little confused (but that's not too unusual) .

If the NEHRP values are "strength values" for use with LRFD type method
why are the values only 16%  higher than the UBC values which are
working stress type values??

Typically we find ultimate strengths for plywood panels to run from
about 625 plf (3/8 ply w/ 8d box (.113 x 2.375") @ 6"/12")  to 1400 plf
(3/8 ply w/ 8d common (.131 x 2.5)  @ 3"/12"). These are results of
cyclic tests run per SEAOSC Panel Test Method.

regards

 Robert Kazanjy, PE  **Disclaimer: I speak for myself not UC-Irvine**
 Senior Development Engineer
 Civil & Environmental Engineering
 UC Irvine
 E4130 EG,  Zot: 2175
 rkazanjy(--nospam--at)uci.edu



Tim.Sheckler(--nospam--at)fema.gov wrote:

> Sam,
>
> You are correct in your statement that the 1997 NEHRP Provisions has
> higher
> shear values for wood shear walls. The 97 Provisions do in fact use
> LRFD
> (strength) design for wood design.  ASCE 16-95 is referenced in the
> text of
> Chapter 12.
>
> Tim Sheckler
>
> ___________________________________
> Tim Sheckler, P.E.
> Federal Emergency Management Agency
> National Earthquake Program
> 500 C St., SW  Room 416
> Washington, DC 20472
> (202) 646-2834
> tim.sheckler(--nospam--at)fema.gov
>
> ____________________Reply Separator____________________
> Subject:    FEMA 302
> Author: seaoc(--nospam--at)seaoc.org
> Date:       7/7/98 9:13 AM
>
> Has anyone noticed that the factored shear values for wood shear walls
> in FEMA
> 302 NEHRP
> Recommended Provisions for Seismic Regulations for New Buildings and
> Other
> Structures
> Table 12.4.3-2a are about 17% higher than the 1997 UBC allowable
> values?
>
> For 7/16" OSB with 8d nails the shear per linear foot is:
>
>     NEHRP
>      UBC
> 6" O.C    4" O.C.    3" O.C.    2" O.C.               6" O.C.    4"
> O.C.    3"
> O.C.    2"
> O.C
> 280 plf    410 plf     530 plf      680 plf                240 plf
> 350 plf
>    450
> plf     585 plf
>
> Is NEHRP based on Ultimate strength while UBC is based on working
> stress?  This
> is very
> important since the 2000 IBC structural provisions will come from
> NEHRP.
>
> Sam Love
> Love Engineering
> Ogden, Utah
>
>