LRFD Design in the NDS and Deflections
LRFD Design in the NDS and Deflections
(OP)
I'm trying to make the jump to the ASCE7-10 Windload provisions, which are all strength based.
When I calculate my shearwall and diaphragm deflections based on the NDS Deflection equation (4.3-1) in the new 2012 NDS
do I need to convert my unit shear to a service level shear values? I was taught that all deflections are calculated with
service level loads. In NDS 2012 Section 4.3.3 they say that the ASD Unit shear is the Ultimate Shear divided by 2.0.
Is it as simple as dividing my ASCE 7 values by 2.0?
When I calculate my shearwall and diaphragm deflections based on the NDS Deflection equation (4.3-1) in the new 2012 NDS
do I need to convert my unit shear to a service level shear values? I was taught that all deflections are calculated with
service level loads. In NDS 2012 Section 4.3.3 they say that the ASD Unit shear is the Ultimate Shear divided by 2.0.
Is it as simple as dividing my ASCE 7 values by 2.0?






RE: LRFD Design in the NDS and Deflections
I don't think you're using any values from ASCE 7 as to the diaphragm. If you mean loads, no. You're using 1.0 W for LRFD and 0.6 W for ASD. That's not dividing by two. The divide by two is accurate for (capacity) of diaphragms in SPDWS, but doesn't pertain to deflection calcs. Diaphragm capacity in SPDWS for LRFD is multiplied by some ASCE specific value that's not 1.0. I don't know it, but it's not 1.0. It's a phi or a lambda or a time effect factor or something.
--Brian
RE: LRFD Design in the NDS and Deflections