DRIFT CALCS

[EBAT75]

What is recommended method to calculate first order Delta and acceptable for the exam? 

 

[EBAT75]

Moderator, in case this post can be construed as transgressing NCEES exam integrity policy, please delete it. My intent was to see if anyone used a given method and achieved Acceptable on the problem as a whole. Nothing more.

 

[thedaywa1ker]

By hand

Edit: Can you be a little more specific?  Do you have a particular material or lateral system in mind that you're asking about methods of calculating deflection for?  My answer was tongue in cheek because the question is a little vague...happy to give you my thoughts.  From what I've seen on the NCEES practice exam and the AEI class, it seems like a lot of the afternoon questions will be focused on loading and detailing requirements...I could see them asking for drift though I suppose

 

[kevo_55]

EB, you are good.

I assume that you are talking about steel. Any method allowed by chapter C if the AISC is acceptable. It's as easy as that.

If you are a member if AISC, design guide #28 can definitely help and give you quite a bit of insight on this topic. If you are a member, you can download this for free. If not, you can buy it. 

But if you are simply looking at what is required for the exam, anything in chapter C is just fine.

 

[EBAT75]

Thank you daywalker and kevo.

Yes, by hand at the exam. I like the humor. i kept this general because stability analysis of both steel and concrete frames run on parallel tracks. Both involve using Delta. However, the examples I have seen give the deflection-delta value rather than calculate it. e.g. Seismic Manual - Moment Frame Ex. 2.4 Taken from software I think.

if I have to calculate it, I am thinking  of applied force divided by rigidity (calculated from stiffness parameters). At least for simpler moment frames. 
 

 

[Andy Lin]

I think if the exam asks you to calculate it, it'll most likely tell you which method to use (for consistency in grading).