# NCEES SE Study Material



## McEngr (Mar 15, 2011)

Problem 104 is the first error I've found (only done 4 problems so far), and they forget to include the Cu factor in determining the period. T=Cu*Ta. They use Ta in the problem, but the answer would most closely match A anyways...

FYI.


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## McEngr (Mar 15, 2011)

McEngr said:


> Problem 104 is the first error I've found (only done 4 problems so far), and they forget to include the Cu factor in determining the period. T=Cu*Ta. They use Ta in the problem, but the answer would most closely match A anyways...
> FYI.


Also on problem 102, maybe someone can direct me as to why the building has an occupancy category of I (low hazard). It's a warehouse. They don't seem to say anything more than that. Am I missing something?


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## brosenbe (Mar 24, 2011)

McEngr said:


> McEngr said:
> 
> 
> > Problem 104 is the first error I've found (only done 4 problems so far), and they forget to include the Cu factor in determining the period. T=Cu*Ta. They use Ta in the problem, but the answer would most closely match A anyways...
> ...


The problem says that it is a "minor storage facility", which is specifically listed in Occupancy Category I in ASCE 7-05 (Table 1-1). (Hopefully I'm looking at the same problem book...)


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## McEngr (Mar 24, 2011)

brosenbe said:


> McEngr said:
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> > McEngr said:
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I suppose I'm not accustomed to looking at the occupancy categories in ASCE 7, moreso in IBC 2006/2009. You are correct.


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## brosenbe (Mar 24, 2011)

McEngr said:


> brosenbe said:
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> > McEngr said:
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No problem. Gotta love the strict adherence to the code...makes this process so much more fun. (FYI, it's also in IBC 2006 Table 1604.5)


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## Ble_PE (Mar 24, 2011)

McEngr said:


> Problem 104 is the first error I've found (only done 4 problems so far), and they forget to include the Cu factor in determining the period. T=Cu*Ta. They use Ta in the problem, but the answer would most closely match A anyways...
> FYI.


It's my understanding that T=Cu*Ta is only the upper limit of T, not the fundamental period itself. Without performing an analysis to find T, the only option we have in that problem is using Ta as T, which is allowed per ASCE 12.8.2:



> As an alternative to performing an analysis to determine the fundamental period, T, it is permitted to use the approximate building period, Ta.


Let me know if I'm missing something here...


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## McEngr (Mar 24, 2011)

Ble_PE said:


> McEngr said:
> 
> 
> > Problem 104 is the first error I've found (only done 4 problems so far), and they forget to include the Cu factor in determining the period. T=Cu*Ta. They use Ta in the problem, but the answer would most closely match A anyways...
> ...


Well, if we are to be specific, Ta="Approximate" fundamental period, and the problem statement should have been more clear in my opinion.


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## McEngr (Mar 24, 2011)

Well, if we are to be specific, Ta="Approximate" fundamental period, and the problem statement should have been more clear in my opinion.

I am trying to figure out the purpose of the T max. Is it for the Cs(max) equation or if you are to use an eigensolution / SRSS? Any comments would help me out. Thanks!


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## Ble_PE (Mar 24, 2011)

I don't think the problem needed to be worded any differently at all because even though Ta is the approximate fundamental period, it can be used for any design per the code. That means you can use that equation to calculate the period of the building in lieu of performing a substantiated analysis. No ambiguity there at all. :dunno:


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## kevo_55 (Mar 24, 2011)

McEngr said:


> I am trying to figure out the purpose of the T max. Is it for the Cs(max) equation or if you are to use an eigensolution / SRSS? Any comments would help me out. Thanks!


The value for Tmax is really for the seismic force determination via Modal or Seismic Response. (Note: both modal &amp; Seismic response can use eignsolution &amp; SRSS methods.)

Ok, I can't believe I still had that in me. I'm done for today....


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## McEngr (Mar 24, 2011)

Thanks kevo and brosenbe, I recall now that Ta can be used. I usually design low-rise and probably have had the upper T limit on a few of my calc checks for the upper limit of Cs... oh well. I doubt anything would surface being incorrect. It's been a while since I've studied this and a little embarrassing that I asked without checking.


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