# couple questions for Structural I people



## wimp (Sep 25, 2007)

Wood design...

I have the timpber design manual (green one). It is based on the 1997 NDS. Pretty similar. Very good book, but why are the 1997 Fv values almost half of the 2001 Fv values? What changed between those two codes?

second question deals with flat use factor Cfu and Size factor CF. If you have a 2x6 being used on the flat (for some reason), you would use the flat use factor when calculating the allowable stresses. What about the shape factor? is the member 2" deep? 6"deep? or is the shape factor not used at all in conjunction with Cfu?

thanks :reading:


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## pelotoner (Oct 16, 2007)

Wimp,

Check out NDS 4.3.7, for Cfu: Fb is allowed to be used in table 4A, 4B, 4C and 4F. Look at the page prior to table 4B and it says that the size factor (Cf) is already incorporated. The other tables are similar or they say that "dimension lumber 2" to 4" thick shall be multiplied by the following size factors." In other works, omit that factor.


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## pelotoner (Oct 18, 2007)

Sorry, just replying to have posting permission...


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## ODB_PE (Oct 22, 2007)

More NDS -

I own the 2005 NDS and I have access to the 1997 NDS. I'm not going to be able to get my hands on the required 2001, however. I've been working practice problems using the 2005 NDS with no big noticeable differences so far, but I'm wondering if the 2005 is the best one to take in.

My reasoning tells me there's no way they would test on something that changed from 1997 to 2001 and again in 2005, but admittedly that is probably naive - so I enter with the 2005 knowing that I could eat 2 or 3 questions. Thoughts appreciated.


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## pelotoner (Oct 23, 2007)

Deadbeat,

I have been designing with NDS 2001 for four years now, but am taking the 2005 into the exam. The only difference I have found was in section 15.3.2 (page 135) for builtup columns. For 2005, Fce = .822*Emin/(le/d)^2; but for 2001, Fce = KcE*E'/(le/d)^2. See your NDS 1997 for KcE

Best of luck!


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## ODB_PE (Oct 25, 2007)

pelotoner said:


> Deadbeat,I have been designing with NDS 2001 for four years now, but am taking the 2005 into the exam. The only difference I have found was in section 15.3.2 (page 135) for builtup columns. For 2005, Fce = .822*Emin/(le/d)^2; but for 2001, Fce = KcE*E'/(le/d)^2. See your NDS 1997 for KcE
> 
> Best of luck!


Well sure, that change makes perfect sense!

Thanks for the tip - I never woulda found that -

I've never taken a formal wood class but I can find my way around the NDS generally OK - but no doubt I'll be eating a couple of these questions.... and most of the bridge....and a good part of the seismic......and a little of the concrete and steel.... Aw hell!

Good luck to you also.


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