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

Re: Existing shearwall with new penetrations

[Subject Prev][Subject Next][Thread Prev][Thread Next]

My approach has been to take the loads from the current code and compare
them to the capacities of the members from the code at the time the
members were designed.  I would do this unless the jurisdiction has
adopted a code or an ordinance that stipulates some other value to be
used for these particular existing elements or materials.

I have never had a building official question me on this.  If there is
one out there ( or any one else for that matter) who would like to do so
now, I would welcome their comments.

As codes evolve and get more restrictive, elements that were once code
compliant, are no longer code compliant.  Do you have to retrofit all
elements and connections that are in some way impacted by your
alterations to comply with the current code capacities and stipulations?
What if you have a concrete shear wall in a structure built 10 years
ago.  Your end elements are probably not going to be in compliance with
the current code.  Does this mean this shear wall has no capacity or
that you have to gunite extra hoops and longitudianl steel around the
end elements?  If you do, now you have to develop this steel into the
foundation and the floor slabs.  What if they do not have the capacity
by today's code?  You can carry this logic on with so many examples.

You have to be able to use some judgement.  Atleast give the element
credit for the capacity under which it was designed (again, unless there
is code explicitly stating otherwise).  If the new loads exceed the old
capacities, then you need to retrofit.

Jeff Coronado, S.E.
West Covina, CA

Joseph M. Otto, P.E. wrote:
> It was my understanding that when you check an existing shear wall to see if
> you can put penetrations into it, you have to use current UBC design loads
> and make sure it can withstand these loads per the current UBC requirements.
> Isn't this correct?
> Joe
> -----Original Message-----
> From: Jeff Coronado [mailto:"jcse(--nospam--at)"]
> Sent: Friday, June 09, 2000 7:34 AM
> To: seaint(--nospam--at)
> Subject: Re:
> Joseph, you are not designing a new wall.  What is the capacity of the
> wall according to the code that was current at the time the wall was
> designed?  Then it seems to me that that is the capacity of the wall you
> have to begin with.
> Jeff Coronado, S.E.
> West Covina, CA
> Joseph M. Otto, P.E. wrote:
> >
> >
> >
> >
> > [Image]
> >
> >
> >
> >
> > January 7, 2000
> >
> > I have been requested to place new penetrations into an existing
> > plywood shearwall which is sheathed with 1/2" ply. both sides nailed
> > with 10d nails at 4" on center at plywood panel edges and 12" o.c. on
> > the field.  The edges of the panels are nailed to the same 2X studs on
> > each side of the wall.
> >
> > Table 23-II-J-1 footnote 2 (page 2-288) of the 1997 UBC indicates that
> > these studs need to be 3X.
> >
> > Does this mean that I  can't use these walls to take shear?
> >
> > :Respectfully,
> >
> > Joseph M. Otto, PE
> > Civil Engineer, Project Manager
> > Ireland Engineering, Inc.
> > 46750 Fremont Blvd., Suite #204
> > Fremont, CA 94538
> > (510) 438-9632 x11    FAX (510) 438-0689
> > jmo_engineering(--nospam--at)
> >
> >
> >  [Image]