dozer
Structural
- Apr 9, 2001
- 506
I'm working on a site that has multiple tiers. Each tier is from 250m to 500m wide then rises 10 or sometimes 15 meters to the next tier. There are 5 tiers. The slope between tiers is 1 on 3.
My question is should I look at each tier as an escarpment in which case you will get a pretty significant wind speed-up at the windward edge of each tier, or should I consider the overall site one big escarpment in which case the H/Lh ratio is less than 0.2 so topographic effects need not be considered.
My reason for going with the latter would be criteria no. 2 in section 6.5.7.1 of ASCE 7-05 (7-10 is the same but I don't have the section numbers handy). To illustrate, let's say my first tier is 10m above the baseline, then the next tier rises another 10m. Since this is not at least twice the first tier, wind speed-up effects need not be considered.
If the second tier had been 20m above the first tier than I would consider wind speed-up effects since 20m is twice 10m.
Does this make sense or am I missing something? Is there any literature on this specific case? I've searched the internet and haven't found anything.
Thanks for the help.
My question is should I look at each tier as an escarpment in which case you will get a pretty significant wind speed-up at the windward edge of each tier, or should I consider the overall site one big escarpment in which case the H/Lh ratio is less than 0.2 so topographic effects need not be considered.
My reason for going with the latter would be criteria no. 2 in section 6.5.7.1 of ASCE 7-05 (7-10 is the same but I don't have the section numbers handy). To illustrate, let's say my first tier is 10m above the baseline, then the next tier rises another 10m. Since this is not at least twice the first tier, wind speed-up effects need not be considered.
If the second tier had been 20m above the first tier than I would consider wind speed-up effects since 20m is twice 10m.
Does this make sense or am I missing something? Is there any literature on this specific case? I've searched the internet and haven't found anything.
Thanks for the help.
