ASCE 7-16 Kzt Factor

[Ron247]

When using Kzt for Topographic Effects (Section 26.8), do you have to use the largest value for all directions of wind or can you use a different value for each direction. The code does not state which one but does say "for each wind direction considered" in the previous section on Exposure (Section 26.7).

I only tend to run into this for buildings on a lake.

 

[JAE]

We've taken the stance that the exposure category and the Kzt factor is unique for each direction...or can be.
It is of course much simpler to assume the worst case for all directions but we think that you can use unique values if needed or desired.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[mekafime]

You can use the maximum for all directions or each value for direction.

Please in this case (picture). How Can I choice values for K1, K2 and K3?

 

[UcfSE]

Same as JAE

 

[EngineeringEric]

I've done calcs with unique K's for the N-S direction and again unique ones for the E-W direction. especially in the case you are talking about on a Lake or similar that only increases force in one direction

 

[Ron247]

Thanks everyone for the helpful input. As far as the sketch depicting the structure in front of the hill, Note 3 for 26.8.1 on page 268 states it must be in the upper half of the hill or near the crest of an escarpment.