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RE: Firewall:(was)CMU Wall Supported by Plyw

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WHAT IS THE MEANING OF         "SNIP"       ????      are you referring to
some attachment(s) that you inadvertently omitted,  since you only comment
on one method after you say there are several ways to accomplish the reqd
result ?


     I appreciate your comments and am currently developing a study on this
very subject.    Is there a good treatise on structural design/detailing for
fire walls???    pls write back - and  thx again



PS:  Our (Kentucky) SEAOK group is writing a White Paper on Firewalls - does
ANYBODY out there have some neat, clean details for these animals? I would
love for you to mail, fax,  or email me
Pls send to:     David Carroll PE
c/o   BFM ENGINEERS, Inc        241 Regency Circle,  Lexington, Ky. 40503
Ph: 859_278-5050 ,,       Fax  859_278-6060




-----Original Message-----
From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
Sent: Thursday, February 22, 2001 12:32 PM
To: seaint(--nospam--at)seaint.org
Subject: Firewall:(was)CMU Wall Supported by Plyw


Scott Maxwell wrote:

. > Now about firewalls...

[snip]

. > The first thing is to realize that there is a difference between a
. > firewall and a fire separation wall.  A fire separation wall is a wall
. > between two spaces that is meant to stop or slow the spread of fire.  A
. > fire wall is essentially a fire separation wall that MUST remain
standings
. > AFTER one side of the building has collapsed (or is one of the two
. > buildings has collapsed).

. > If you must have a firewall, then that wall between the two buildings
must
. > be designed in a fashion that it would remain standing if either
building
. > collapses.  Thus, if the new building falls, then the fire wall MUST
. > remain standing or if the existing building falls, then the fire wall
MUST
. > remain standing.

. > This can typically be done one of several ways.  You can:

. > 1) [snip]

. > 2) Do a single wall that is tied to each structure that has "break away"
. > connections so that one side can fall without causing the other to
. > collapse or bringing down the wall.  With a masonry wall with wood
joists,
. > this has traditionally been done with a "fire cut".

. > 3) [snip]

It seems to me that a "fire wall" would be virtually impossible in seismic
country as the code requires that the diaphragm be tied to masonry/concrete
walls.  "Fire cuts" would be ineffective as the joists are tied to the wall
with "tension ties" or other anchors.  A "fire cut" would only be effective
for wood joists resting on or in walls without any other type of connection
between the joist and the wall.  For a fire cut to be effective with tension
ties, the tension tie would have to be a fusable link and even then it is
questionable whether that would work, e.g., a fire destroys the wood joist
at
mid-span, but does not reach releasing temperature at the fusable link at
the
wall.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona