wind loads for 2 buildings with expansion join

huangyhg

wind loads for 2 buildings with expansion joint
greetings,
i am desiging 2 buildings separated by an expansion joint. i want to get some guidance as far as using figure 6-9 of asce 7 to apply wind loads.
here are my concerns:
figure 6-9 applies to buildings with no exp. joints. how would you modify this to account for the fact that one of the sides would have a side wall pressure in addition to the positive and negative.
how would torsion be modeled? does anyone know the origins of figure 6-9. i am assuming the torsion is arising from a 45 degree wind (0.707w, which is conservatively upped to 0.75w??) however, any input you might have would help.
thanks
if there is a good possibility that these two buildings will have separate owners then you should design each to take the full wind load. this is because one may be demolished prior to the other.
that said, when you design for the wind perpendicular to the joint, you need to include the internal pressure anyhow so it probably wont make much difference.
if your lateral resistance is at the center of your wind load applied, then there will be no torsion.
csd2,
thank you for your response. this is a school building which has an odd change in a diaphragm width, plus it is about 400 ft. long. hence, the joint.
for wind parallel to the joint, the side pressure will exist only on one side and not the other. there won't be any side pressures (they will cancel) for wind perpendicular to the joint.
i think you are talking about the inherent torsion in the building. i am referring to the code-imposed torsional load that i am required to apply. this torsion apparently is due to the non-uniform pressures caused by wind on different faces.
if you have shear walls in the outer walls then this just results in a higher load on one wall than the other.
the side wall wind just creates a biaxial load, the building should be checked for the worst case of this and of the 0.75w oblique load.
as a follow up to my question, would the eccentricity for applying torsional load be based on the total building width or width of one of the buildings?
thanks
that is a very good question - i cant answer that one. conservatively you could take it for both.