×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

LRFD Design in the NDS and Deflections

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?

RE: LRFD Design in the NDS and Deflections

The diaphragm values you want are in SPDWS. The properties (E, G/in, etc,) don't change for LRFD/ASD. As to the forces, you have to drop those to ASD level to check deflections. Generally in 7-2010 you use 0.6 W for ASD (and deflection calculations).

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

(OP)
Brian, Where do you get the 0.6W for ASD to LRFD conversion?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources