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RE: Firewalls

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Hello Mike,

The problem is if the wall is a bearing wall not a shear wall.  If the wall
is a shearwall you can connect it to the roof diaphragm and if one side of
the building burns down the other side is still standing.  If the wall is a
bearing wall supporting  the roof on both sides of the wall then there is a

Another thought: typically building frame systems have lower response
modification factors and lower seismic loads than bearing wall systems. If
you support the roof framing on a complete space frame and not the shear
walls then you can get away with lower seismic loads [there can't be a
bearing wall system in either direction].


Scott M Haan  P.E.
Plan Review Engineer
Building Safety Division, 
Development Services Department,
Municipality of Anchorage
phone: 907-343-8183   fax: 907-249-7399

> -----Original Message-----
> From:	Michael Zaitz [SMTP:mzaitz(--nospam--at)]
> Sent:	Thursday, March 29, 2001 4:09 AM
> To:	Structural Engineers Association
> Subject:	Firewalls
> Hello All;
> Sometime back the issue of 4 hour firewalls that allows the structure to
> collapse on either side of the wall without affecting the structure on
> the other side of the wall.   I have a wall that is now required to be a
> 4 hour wall (due next week) and as such I need to do something to allow
> the collapse.  To make matters worse the wall is a shear wall (or at the
> moment it is).  I remember talk of anchors that will melt of allowing
> the structure to fall but did not see anything in the archives that had
> any manufacturers or the like.  Coould someone provide me with some
> information or some leads as to where to find information on these types
> of anchors?
> Thanks,
> Mike