huangyhg

fire walls (again)
i have read previous posts on this topic. i am making a new post b/c i have a different situation.
the project is a group of 8 seperate buildings. the buildings are as close as 19'... connected by light frame covered corridors.
the architect has been told that the end walls of some of these buildings need to be firewalls. we are ibc2006.
well, if the end walls are to remain in place while the building burns for two hours... then they will be totally free standing. originally i had my buildings braced by shear walls... now i am thinking i may have to start from square one with a different lfrs.
i am curious as to where the code requires a fire wall and whether it needs to be the entire length of the parallel faces... or just the part where the 19' long connector is.
i have found the requirements of a shear wall in 705 & 705.2... but i can't find where it prescribes the need.
i don't have my code handy but there is usually a requirement that the firewall needs to extend a few feet beyond so that a fire cannot jump around the wall. the architect should be familiar with that section of the code.
you might also doublecheck with the architect to see if the owner's underwriter is fm....if so you need to also meet their requirements.
you might still be able to use the firewall as a shear wall depending on your wall material. if it is masonry, maybe using epoxy anchors to transfer loads would work. some if not all usually have a melting point well below that of a fire and the epoxy would melt away before the roof or floor gave way. maybe. i have heard of it done, but havn't actually seen it done myself...maybe something to look into.
ibc-03 1021.1
there are different requirements for "fire walls". the most extreme case is governed by area and height limitations where in fact you end up with two separate buildings side by side. depending upon the use groups the fire resistive rating will vary.
there are also fire resistive walls with lesser requirements for specific rooms, stairs, shafts, distance from property lines. the insurance company can also stipulate fire walls with more or less extreme measures to isolated insured values. (usually storage or industrial operations) and minimize risk.
i recommend that you have the architect tell you what your design criteria is. structurally (for interior walls) it can mean free-standing cantilever walls, or double column lines with two walls each braced by its own structure.
also there maybe requirements for fire rated extensions beyond the building horizontally, or on each side of the fire wall as it penetrates the roof. (like concrete slabs). this is the architects job to determine. have him forward you his written code review with the design criteria outlined for you to follow, that way you can see how it is done. (and also protect your firm)
work with your architect as see if some or all of the walls can be fire separation (or fire barrier) walls rather than true fire walls.

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