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NCEES Civil Morning Problem 119


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#1 Lucky1

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Posted 28 January 2012 - 02:55 AM

From 2011 NCEES Civil: Construction Samples & Solutions Book

Can someone explain this concept and point out where it is in CERM? It's a simple problem but I am not seeing the concept.

Thanks.

#2 treyjay

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Posted 28 January 2012 - 03:19 AM

look in strengths of materials

#3 Dano_PE

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Posted 27 March 2012 - 11:42 PM

I am lost on that one too. Also if you have the old NCEES practice exam (highly recomended from 2008) i am lost on question 112 as well. Same type thing. I am not a structual guy. There is an easier way to make a living in my humble opinion.

#4 Lucky1

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Posted 28 March 2012 - 07:24 AM

Dano,

I feel your pain. Problem 112 (from 2008 book) makes more sense from a common sense standpoint. However, like you I am not structural and would like to see in black and white the concepts to make sense of both of these problems.

#5 treyjay

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Posted 28 March 2012 - 03:10 PM

Dano,

I feel your pain. Problem 112 (from 2008 book) makes more sense from a common sense standpoint. However, like you I am not structural and would like to see in black and white the concepts to make sense of both of these problems.



I don't want to sound like I am putting you down, but if Problem #119 of 2011 NCEES Construction Sample Exam is getting you hung up, you better really start to focus & concentrate. this problem is an FE type of question. it is a strengths of materials topic and doesn't have anything to do with being a structural guy or not. you are trying to find the largest moment of interia and you need to use the parallel axis therom.

like I said, I dont mean any disrespect, but this is basic stuff.

#6 Dano_PE

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Posted 29 March 2012 - 09:19 PM

and I definitely knew it well on the FE but it has been a long time. Thanks for the info. No offense taken.

Dano-

#7 Dano_PE

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Posted 29 March 2012 - 09:24 PM

Lucky 1 look on page 44-11 in the cerm equation 44.37. As you know Mc = Mmax x C.

Trey jay is right. You need largest Ic. Which would yeild less bending stress (ie stronger beam).

Correct me if I am wrong anyone.

#8 Jayman_PE

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Posted 30 March 2012 - 12:57 AM

You are 100% correct.

#9 Lucky1

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Posted 30 March 2012 - 02:35 PM

Thank you. I had been hung up on the distance from the centroidal axis in the moment of inertia equation for two beams of the same size rotated 90 degrees from each other (choices c and d in the problem). A registered SE walked me through this today and the light bulb finally went back on. Like Dano the years have passed since the FE and despite reviewing this concept in CERM the little hangup didn't make sense until the SE explained it and now it seems simple. Your comments help, also.



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