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Re: Firewall Connection

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Derek,

        I've usually interpreted the 0.5 kPa from a fire as being applied to one
bay or one storey height and not the whole wall.  Also, presumably, the building
on the other side of the wall is still there to provide support.

        For "after the fire" when the wall is left free standing I wouldn't
think it necessary to design for any more than the ten year wind load for the
suction side of the building.  For many inner city situations this may be of the
order of 3 or 4 p.s.f.

Regards,

H. Daryl Richardson

Derek wrote:

> <<Follow-up question:  What do you design the walls for, especially a
> cantilever?  I have seen some folks design this for the 5psf interior wall
> condition and equake.  We use a full code wind load and check equake.
> Reasoning is that IF the structure comes down this wall will be hanging in
> the breeze for a while, possibly forever.>>
>
> NBCC requires firewalls be designed for a factored load of 0.5kPa (10.5psf)
> under fire condition.
>
> -----Original Message-----
> From: John C. Jones [mailto:john(--nospam--at)struct-engr.com]
> Sent: Thursday, July 15, 2004 0524
> To: seaint(--nospam--at)seaint.org
> Subject: RE: Firewall Connection
>
> I have seen this done two ways.
>
> 1.  Provide 2 doors separated by a door swing plus an ADA distance.  This
> only works where you have an alcove or a corridor.  What you do is build the
> majority of the length of the 2 firewalls as you normally would.  When you
> come to the opening the wall steps away by the distance mentioned.  The is
> for the below ceiling condition.  Above the ceiling the wall doesn't change.
> At the ceiling you build a concrete slab.  We usually call this one the
> tunnel method.
>
> 2.  Build walls in usual manner.  At the door you provide CIP columns and a
> beam/slab at the ceiling.  Inside this you  provide only one door.  The
> thinking on this is that the CIP is freestanding.  It's built bombproof.  On
> the top level of the CIP beam/slab you provide a sloping surface with felt.
> The block firewalls are built on top of the sloping surface.  The sloping
> surface looks like the ridge of a roof with the ridge parallel to the wall
> and between the block wythes.  The thinking is that if there is a fire and
> it pulls the block then you are helping it do so with the slope.  Your
> structure below is built where it is "bombproof" and won't move.
>
> John C. Jones, PE
> Barnett Associates
> Pell City, AL
> 205-884-5334
> 205-884-0099 (fax)
>
> -----Original Message-----
> From: Rick Burch [mailto:rburch(--nospam--at)conterra.com]
> Sent: Wednesday, July 14, 2004 6:40 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: Firewall Connection
>
> Jim, and others who mentioned using double walls,
>
> Here is a question  that has always puzzled me, and which I posed the
> last time  the firewall question came up on the list:
> What do you do at door openings through the double walls - put doors in
> both walls? I know some firewalls might not have openings, but it seems
> that all of them I have encountered had door openings. I don't think I
> have ever seen two sets of doors right up against each other however,
> like would be required in a double wall.
>
> Rick Burch
> Columbia, SC
>
> Kestner, James W. wrote:
>
> > I would recommend using a double firewall in this instance.
> >
> > Jim K.
> >
> >
>
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