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RE: 'R' Values

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Thor,
 
Try finding system(s) with the same "R" value in IBC, then find the Rd*Ro for the same system(s) in BCBC and go as conservative as you see fit. Check the deflections too.
 
Reza Dashi P.Eng
Vancuver,BC 
 
> From: vicpeng(--nospam--at)telus.net
> To: seaint(--nospam--at)seaint.org
> Subject: RE: 'R' Values
> Date: Mon, 5 Oct 2009 16:24:45 -0700
>
> Hi Scott.
>
> I'm familiar with the 'R' concept but was trying to see the equivalence of
> our Rd*Ro to the US 'R'.
>
> Thanks
>
> Thor
>
> -----Original Message-----
> From: Scott Maxwell [mailto:smaxwell(--nospam--at)umich.edu]
> Sent: Monday, October 05, 2009 2:58 PM
> To: <seaint(--nospam--at)seaint.org>
> Subject: Re: 'R' Values
>
> Hocus pocus.
>
> If I try engage my serious mode...
>
> R vlaues, in theory, are to represent the amount of ductility relative
> to a purely elastic system. The idea is a purely elastic response
> would have an R of 1.0. The higher the R value, the more ductile the
> system will behave.
>
> Now, in theory, you can think of this a relative measure of the energy
> of the system response or the area under the curve of plot load vs
> deflection for a system. Nominally, in theory, a system with an R of
> 5 will be able to dissipate 5 times the energy than that of a system
> with a pure elastic response.
>
> In reality, R values have never really been done purely based upon a
> rational method. The have more been a function of "politics" (i.e.
> Kind smoke-filled backroom agreements). While they are not complete
> BS, they can not currently be determined from a rational engineering
> method.
>
> In theory, this is potentially going to change. There is an effort to
> make R values be more rational. This part of the reason why Appendix
> A of the SIP ICC-ES acceptance requirements was killed (this assumes
> you read my long dissertation post on SIPs for lateral loads).
> Personally, I have lost track of where this effort stands.
>
> HTH,
>
> Scott
> Adrian, MI
>
> On Oct 5, 2009, at 4:47 PM, "Thor Tandy" <vicpeng(--nospam--at)telus.net> wrote:
>
> > Showing my ignorance of IBC/UBC through little use thereof.
> >
> >
> >
> > What makes up the 'R' value? I'm trying to align some Hardy Frame
> > table
> > values (quoting 'R'= 5.5 & 4.4) with the local 'R' for loads I'm
> > using here
> > in BC.
> >
> >
> >
> > No doubt apples & oranges . :^)
> >
> >
> >
> > Thanks
> >
> >
> >
> > Thor A. Tandy P.Eng, C.Eng, Struct.Eng, MIStructE
> > Victoria, BC
> > Canada
> >
> >
> >
> >
> >
> >
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