ASCE7-10 Table 15.4-2 1

[msquared48]

What is meant by the term "Not similar to Buildings"? Obviously "similar to buildings' would be the opposite.

Does this mean no diaphragms, or does it have to due to the concept of lumped masses, as in equipment supported on an open steel framework with catwalks as needed, as opposed to a uniform dead load at each floor, as in a concrete floor?

Logically, I would think it would be the lumped mass idea.

Is there a written reference for the code definition?

Mike McCann, PE, SE (WA)

 

[JAE]

Read through the commentary C15. It has quite a bit of discussion on the differentiation between "like" and "not like" building structures.

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[msquared48]

Thanks JAE. I will.

NEHRP seems to suggest the difference is the seismic response.

Mike McCann, PE, SE (WA)

 

[TehMightyEngineer]

Don't forget that if you have the first or second printing of ASCE 7-10 you wont have the expanded seismic commentary. See here if you need to download it along with any applicable errata and supplements:

http://skghoshassociates.com/SKGAblog/viewpost.php?id=38

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

http://www.americanconcrete.com

 

[msquared48]

Man, is the narrative convoluted or what! I will need some antacid here...

Mike McCann, PE, SE (WA)

 

[TLHS]

There's lots of text there, but it's pretty straightforward. If it would respond like a building and has a lateral system like a building, them it's similar to a building. Other things aren't. I really think there's more gray area between non-structural components and structures not similar to a building, when you get into equipment design and things like that.

 

[msquared48]

TehMightyEngineer:

Supplement #1 is not found in the link above, but the others are...

Mike McCann, PE, SE (WA)

 

[TehMightyEngineer]

Try here:

http://www.asce.org/structural-engineering/sei-supplements-and-errata/

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

http://www.americanconcrete.com

 

[JoshPlumSE]

I haven't reviewed the commentary recently, so I may easily put my foot in my mouth. But, I tend to look at it as a Mass and stiffness issue.

Is the mass of the structure distributed relatively evenly between floor levels, like it would be for a building? Sure you can have some mass irregularities. But, conceptually could this be like a building, or is all the mass lumped at one level in a way that you'd never see for buildings?

Is the structural system similar to what you'd get in buildings with clearly defined floor levels and such? Where the various lateral frames are tied together in clean ways similar to a rigid diaphragm. Are you anticipating getting some really odd modes related to the geometry that you just wouldn't ever see with buildings?

That's sort of a mile high view of how I look at it conceptually. I'm really thinking of the dynamic behavior and mode shapes of the structure and whether or not it matches up well with the assumptions we have for building structures. I would hope the concept gets explained in greater detail in the commentary....

 

[msquared48]

Thanks for your insight Josh - kinda what I am reading into the mix too.


I am stillreading... when I can...

Mike McCann, PE, SE (WA)