Drift Loading Cause By Tall Structure
Drift Loading Cause By Tall Structure
(OP)
Hey all!
Hope everyone is ready for a long weekend (at least those in the U.S.)! I am doing a little preliminary research for a small project that we are going to be starting shortly. It is a corridor built along a series of silos. My question becomes, is there any additional literature available on the topic of drift loading near a tall structure >50'+ above the lower roof. If I apply ASCE's drift loading for the indicated structure on plan, I get a maximum drift load of about 30 psf (pg=30psf). My gut tells me that I should be adding a much larger quantity of snow to the roof, but I am unsure of how to quantify it. I feel as though there should be somewhere in the area of 100 psf max snow load. If anyone has any additional information that would be great. Applicable codes for the region are ASCE 7-05 and IBC 2009.
Thanks Much!
Hope everyone is ready for a long weekend (at least those in the U.S.)! I am doing a little preliminary research for a small project that we are going to be starting shortly. It is a corridor built along a series of silos. My question becomes, is there any additional literature available on the topic of drift loading near a tall structure >50'+ above the lower roof. If I apply ASCE's drift loading for the indicated structure on plan, I get a maximum drift load of about 30 psf (pg=30psf). My gut tells me that I should be adding a much larger quantity of snow to the roof, but I am unsure of how to quantify it. I feel as though there should be somewhere in the area of 100 psf max snow load. If anyone has any additional information that would be great. Applicable codes for the region are ASCE 7-05 and IBC 2009.
Thanks Much!






RE: Drift Loading Cause By Tall Structure
RE: Drift Loading Cause By Tall Structure
I hope this doesn't ruin your weekend.
RE: Drift Loading Cause By Tall Structure
However if you wanted to argue for a higher load you would take height of the windward and leeward snow and add them together.
EIT
RE: Drift Loading Cause By Tall Structure
SG: Impact loads are something I will have to evaluate.
RE: Drift Loading Cause By Tall Structure
RE: Drift Loading Cause By Tall Structure
Another approach could be (very conservataive) - Assume all the (balanced) snow from the six silos drifts on the entire length of the corridor in the form of a triangular loading.
Impact should not be of concern for snow drift with a elevation difference of about 50 feet. Ice - may be.
Canadian codes are very exhaustive when it comes to snow loads. They have provisions for calculating drifts from higher roofs with parapets (parapets and screen walls affect snow drifts significantly), canopies adjacent to tall buildings etc.
RE: Drift Loading Cause By Tall Structure
RE: Drift Loading Cause By Tall Structure
By the way I live and work here in U.S.
RE: Drift Loading Cause By Tall Structure
Sorry - I'm not trying to hijack the thread.
Thanks.
EIT
RE: Drift Loading Cause By Tall Structure
However, there is another condition where the 50' or 250' number comes into play. For a radio or television transmitter site, there is usually a small building near the tower. Ice buildup on the legs of the tower can become like dangerous missles when a section breaks off. The ice can slice right through a roof if it is not designed correctly or a person.
RF, For starters, How much of the snow is fresh stuff and how much has melted and refrozen as solid ice?