I was wondering if anyone had any insight on the requirements for Kzt. ASCE 7 give some requirements for when it applies, and all have to met, and I'm not sure what some of them refer to. The first requirement states it is "isolated and unobstructed upwind by other similar topographic features of comparable height for 100 times the height....or 2 miles." What is considered a comparable height?
The second requirement is the most confusing one. It says:
2) The hill, ridge, or escarpment protrudes above the height of upwind terrain features within a 2 mile radius in any quadrant by a factor of two or more.
Protrude from what? what is the base elevation to be used? Surely not sea level. Do you figure an average elevation over the entire area of the 2 mile radius? Cause I could have a hill top that is at an elevation of 1000' and the base is 500' and there is a nob in the hill that is at 900'. So the hill is 500' and the nob is 400', which isn't a factor of 2, but what should really be used as the base elevation?
The other question is the H - height of hill relative to upwind terrain. It's easy is you have a single hill in the middle of a plain, but if you're in the middle of a mountain range, what is the elevation of the upwind terrain? Once again, do you assume some average over the 2 mile distance?
The second requirement is the most confusing one. It says:
2) The hill, ridge, or escarpment protrudes above the height of upwind terrain features within a 2 mile radius in any quadrant by a factor of two or more.
Protrude from what? what is the base elevation to be used? Surely not sea level. Do you figure an average elevation over the entire area of the 2 mile radius? Cause I could have a hill top that is at an elevation of 1000' and the base is 500' and there is a nob in the hill that is at 900'. So the hill is 500' and the nob is 400', which isn't a factor of 2, but what should really be used as the base elevation?
The other question is the H - height of hill relative to upwind terrain. It's easy is you have a single hill in the middle of a plain, but if you're in the middle of a mountain range, what is the elevation of the upwind terrain? Once again, do you assume some average over the 2 mile distance?
