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Re: UBC Section 2213.51

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Mark,

It looks like your procedure is sound.  Yes, I do think you have to
factor 1.4 back into E.

As far as your frustration, I don't think I know anyone who isn't
frustrated with this code, or for that matter, the general direction
that the code has been going in over the last few years.

As far as the plan checker is concerned, wow!  This takes "ignorancy
leads to conservancy" to a whole new level.  That person sure doesn't
want to have anything built in their jurisdiction.

Good luck.

Jeff Coronado, S.E.
West Covina, CA


Mark D. Baker wrote:
> 
> > Mark,
> >
> > The UBC section you allude to only applies to columns.  The member sizes
> > you reference appear to be beams.
> 
> I realize this applies to columns, I had however applied omega to the
> lateral load acting on my frame instead of applying omega to the axial force
> in the frame column.
> 
> >
> > I don't recall having to bump up the size of a column so much because of
> > this code provision.  Are you aware that this is a strength expression
> > and you need to factor your column load capacity by 1.7.
> 
> Yes, but this brings me to another question: The frame analysis from which
> the column axial force is taken, is a result of which load combination? Am I
> doing the following correctly:
> 
> 1. Calculate load to the frame.
> 2. Use ASD load combination equation 12-9, 12-10 or 12-11 to analyze frame
> (note E/1.4).
> 3. Take column axial load out of analysis results.
> 4. Check column axial capacity based on section 2213.5.1.
> 
> Here, I get hung up. The frame analysis was done with E/1.4. Now I have a
> column axial load at service level forces to which I'm going to check
> against ultimate capacity (Psc=1.7FaA) of section 2213.5.1?? I do need to
> factor my column axial load by 1.4 prior to checking against Psc, don't I?
> 
> >
> > Since it is the nailer transferring the shear to the frame, don't
> > understand how the nailer capacity can be less than the design shear.
> >
> It can't, don't know what I said to give you that impression.
> 
> > Hope this helps.
> >
> Yes, thanks, it has somewhat but as can be seen above, I am still confused.
> I have spent far to long trying to sort this fu$%ing code out and have just
> about reached my limit.
> 
> You might be interested to hear a local building officials opinion on how to
> design omrf under 97 code. "Design the entire frame for D+2.8E". Don't
> divide E/1.4 and don't take any stress increases. He understood I was
> talking about ASD design for the frame.
> 
> Regards,
> 
> Mark
> 
> > Jeff Coronado, S.E.
> > West Covina, CA
> >
> >
> > Mark Baker wrote:
> > >
> > > The load combinations of section 2213.51 are increasing the size of my
> > > ASD OMRF members from W12x35 to W16x57.
> > >
> > > This frame is located at the end of a 65' x 40' structure, wood framed
> > > with diaphragm @ 26' above fin. flr. The frame is also receiving load
> > > from a 26' x 40' open canopy, wood framed.
> > >
> > > Section 2213.51 states the exception  "Axial load combination need not
> > > exceed max. force that can be transferred to the column by elements of
> > > the structure......".
> > >
> > > I interpret this to mean I can design the nailer/beam connection (for
> > > example) for the applied lateral load (no more, no less) and proceed
> > > with only meeting load combinations of 1612.3.
> > >
> > > If this is true, under what circumstances does one not "cheat the
> > > code" by taking this exception and instead design for the load
> > > combinations of 2213.51?
> > >
> > > Regards,
> > > Mark
> >
> >
>