ASCE Wind Topographic Effect at Valleys
ASCE Wind Topographic Effect at Valleys
(OP)
In the continuation of Figure 6-4 in ASCE 7-05 or Figure 26.8-1 in 7-10, the chart "Parameters for Speed-Up Over Hills and Escarpments", the first Hill Shape has a note under it that says, "or valleys with negative H..." I cannot find anywhere else in the code that says this factor should be applied to a site near a valley. Nor do I understand how one would apply a negative height to the calculation of the K1 variable.
Does anyone have any insight to what this note is referencing or an opinion on if a topographic factor should be applied to a site near a large valley?
Thanks
Does anyone have any insight to what this note is referencing or an opinion on if a topographic factor should be applied to a site near a large valley?
Thanks






RE: ASCE Wind Topographic Effect at Valleys
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: ASCE Wind Topographic Effect at Valleys
Mike McCann, PE, SE (WA)
RE: ASCE Wind Topographic Effect at Valleys
I suppose I see where you are going Woodman treating a valley as a 2-D hill that's inside out, and if my site is in the bottom half it protects me from wind normal to the valley's length. M2, I think I agree with you that the funneling effects are really the biggest concern so I suppose this does not help me with them, and I guess that is a question for the local jurisdiction.
I guess I figured since this note does not seem consistent with the rest of this section in ASCE, that perhaps someone on here with a longer memory than mine might remember something from a previous edition of the code that has been removed, or if it was a hold over from some other reference. What are you going to do though, talk to the local code official I suppose.