Wood Load Duration Factor
Wood Load Duration Factor
(OP)
Ok, I am unclear about how I am supposed to use this Load Duration Factor for wood.
They give you a different factor for each load case (dead, live, wind, etc...). So what do you do in each load combination? Do you prorate the factor based on how much of each load you have?
They give you a different factor for each load case (dead, live, wind, etc...). So what do you do in each load combination? Do you prorate the factor based on how much of each load you have?






RE: Wood Load Duration Factor
This should be in the NDS; if not, it should be in Breyer; if not, trust me ;)
RE: Wood Load Duration Factor
"for the shortest duration load in a combination of loads shall apply for that load combination." If your load combination only includes dead load you will use a CD=0.9. If you load combination includes live load you will use a CD=1.0 and so on. This factor applies to the whole load combination. An example is load cases 5-7 of ASCE 7-05. They all include wind, which is the shortest duration load, so a CD of 1.6 is used to determine you allowable stresses for that combination.
RE: Wood Load Duration Factor
Garth Dreger PE
AZ Phoenix area
RE: Wood Load Duration Factor
For wood, you don't have constant capacity (because of the load duration factor), therefore you have to check demand<capacity for all load combinations.
RE: Wood Load Duration Factor
RE: Wood Load Duration Factor