huangyhg

torsion analysis required?
please refer to the attached roof framing plan.
w9x9 cantilevered 8'-0" from column line l. they are fully welded to w24x55. w12x14 are provided for lateral buckling.
i'm trying to avoid a complicated torsional analysis on the w24x55 along l. is this possible?
please advise.
why don't you provide the w12x14 with a moment connection to take the twist out of the w24x55?
if you detailed the connection of the backspan beam to brace against any rotation in the w24, i think you can avoid torsional analysis, but you still need to determine the loads from the w6.
also make sure to include weak axis moment in your columns as well.

rc
all that is necessary for the triumph of evil is that good men do nothing.
edmund burke

good advice to use moment connections - i would make the outrigger the same size as the backspan beam so that the load in the flange of the beams transfers straight through the web of the w24 rather than bending it.
it would really depend on th rotation of the w24 under these loads.
one connection that i have seen is to use standard single plat shear connectors either side to take the shear and then flange splice plates top and bottom with no connection to the w24. this theoretically avoids inducing the torsion into the w24.
thanks to all the responses.
the outrigger is part of an architectural feature so it has to be w6.
i have over 250 outriggers so the number of moment connections will have to be minimized to reduce cost.

crazy architects!
i think if your w12 provides bracing at the top and bottom flange of the w24 you don't have to design for torsion. i guess it would be similar to designing a spandrel beam for brick facade on a steel framed building, etc.

rc
all that is necessary for the triumph of evil is that good men do nothing.
edmund burke

to minimize cost, try to make the exterior beam span column to column. then you will only need a moment connection at each column. of course, a w6 may not work for the additional load. if not, you should use a w6 on each side of the w24, and put a moment connection at each w6.
daveatkins
could you drop the w24 by 6" and run the w6 over the w24 tying into the adjacent bent?
just make it a tube section and be done with it.
all you have to do is follow jike's advice in the first reply above. moment connection of w12 to w24.

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