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Re: Fire wall/shear wall on property line

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That's the challenge. You know how much your roof weighs, and what the angle of force is based on different roof segments collapsing (@ less than 24', the force is practically vertical if you use an ideal hinge and an infinitely thin roof). You know how much force your roof connectors (h clips) provide, and you can add a couple of 16d toenails they'll install during erection. You also know how many anchor bolts you plan on putting in to hold the mudsill/plate to the top of the CMU.

With those three, you just have to find the weak point and use that for your design value. I'd ignore the roof-collapse case, since you have two other failure points, and you only need to know one for design (though I'd choose the lesser of the two).  You'll have to make a judgement call whether to use the ultimate load on the connectors or the engineering design load (this is particularly important if you're looking at tested design data which usu. has a 2.5-4 FS of applied to ultimate loads).

I'm not saying this is wrong or right, and you won't find it in the code, but it's basic engineering - tracing your possible load paths to determine loads, and then designing for them. The factors you use for your loads should reflect good judgment and your ability to really assess how this will be erected in the field so that you don't underestimate forces (i.e. toenails placed during truss erection).

Jeff Hedman wrote:



Essentially are you saying to design the wall as a tall fence to resist the wind load or a wall with a drag load from the burning roof collapsing?  The drag force from the collapsing roof will govern my design as this building is completely shielded from the wind on this particular side of the building.  How do I go about calculating the force on the wall for the collapsing roof?  Which direction is this force acting on the wall?





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