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RE: Structural stability of fire walls

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My Nylatron solution has been successfully used in Florida, Missouri and NJ, but it does not comply with FM requirements, which is the source of most of Scott's definitions below, more or less.
 
Matthew Stuart

________________________________

From: Scott Maxwell [mailto:smaxwell(--nospam--at)umich.edu]
Sent: Tue 2/16/2010 9:10 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Structural stability of fire walls


These provisions have long been in effect in non-UBC lands (i.e. BOCA in my neck of the woods and then IBC). 

There are four basic ways that this has been handled in my experience:

1) Cantilevered firewall.  This would be a free-standing firewall that is between the two structures with no ties to either structure where the wall cantilevers from the foundation.

2) "Pilaster" or Freestanding firewalls.  This is nominally the same as #1 except you have columns/pilasters that cantilever from the foundation and the infill wall spans horizontally from pilaster/column to pilaster/column.

3) Tied or Laterally Supported firewalls.  This would be a single firewall that is tied to each structure, but that is done in some "fuse-able" way so that tie can break without pulling down the wall.  This is of the similar mind-set to "firecuts" on wood joists at masonry walls.

4) Double firewall.  This would be two separate firewalls that are each tied to their own structure.  Thus, if one structure falls down and pulls down it associated wall, the other wall will remain standing with the other structure.

In my experience, #4 tends to be the best option even though most architects tend to resist that option strongly.  #1 or #2 can work well if it is a 1 or 2 story building in a relatively low seismic area.  #1 and #2 start to become problematic in higher seismic zones such as CA.  I have never really used #3 as finding a good "fuse-able" connection always seemed to be a major hurdle, but then it has been a LOOOOONG time since I have dealt with this issue and there are likely "advances" that make such "fuse-able" connections more feasible.

The TEK note that Jeremy put on the StructuralPedia site more or less covers these options and has been a good reference on this issue for quite a while.

Regards,

Scott

On Feb 16, 2010, at 12:27 PM, Dave Adams wrote:


	
	Hello all,
	 
	Someone has probably brought this up before, but perhaps not.  How are you all handling the sections of the code which require fire walls to remain standing if the building portion on either side collapses from a fire (Section 705.2, for example)?  I have seen a detail that shows an essentially complete gravity load resisting wall system on each side, thus creating a three-walled fire wall system.  This seems like overkill.
	 
	Thanks,
	 
	Dave K. Adams, S.E.
	Lane Engineers, Inc.
	Tulare, CA
	www.training4engineers.com <http://www.training4engineers.com/> 
	 
	 


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