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FW: Pile/Fdn check check for ortho load comb in SDC D

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Title: FW: Pile/Fdn check check for ortho load comb in SDC D

Harold,
Thanks for your response.  I have one more question on section 12.5.
Pl. refer to ASCE 7-05 section 12.5.
1.  Per 12.5.2, we do not need to take ortho load comb. for Category B structures.
2. Per 12.5.3 a(Category C), we need to consider ortho load comb. only for Structural integrity type 5 structures.
Pipe rack and other refinery structures are straight forward & do not fall in type 5 irregularity.
3. Per 12.5.4(Category D,E & F), we need to consider critical loads(including ortho) only for columns or walls that forms part of two or more

Intersecting seismic force resisting systems & subjected to axial load > 20% of strength…..
This section does not include fdn. & piles of regular structures like pipe rack.

ASCE does not address this issue of considering ortho load comb. for fdn. & piles unless they fall in the above section 12.5.3.

Unless it says in the code/ASCE do we need to consider the orthogonal effect on fdns/piles?  Or is there std. way of doing this like

many engineers take this into consideration(conservative approach?)

Can you pl. comment on this?

Thanks
Ravi Vasu


Ravi,

RE: ASCE 7-05


A pipe rack is part of a category of "nonbuilding structures similar to buildings". This means that they have structural systems and responses that are similar to buildings, but we needed a little latitude regarding the systems that we could use that we could not get if they were defined as a "building". We wanted to use as much of the information as if the systems were part of buildings as we could.

In answer to your quesitons:
When we design the foundation, is there any exception that the fdn & piles need not be checked for orthogonal load combinations?
No

Can anyone point to ASCE/IBC 2009 section about taking or not considering ortho load Comb for fdn and Pile design?
Section 15.1.1
We did not provide any changes or modifications to the design of foundations, nor did we develop any exceptions to Section 12.5. Looking at Section 15.1.1 "....Design shall conform to the applicable requirements of other sections as modified by this section. ...." Thus Section 12.5 is not modified and is applicable.

Chapter 15 was not intended to stand alone. It provides modifications to other sections of the ASCE 7.

The ASCE 7-10 is written similarly.


Regards, Harold Sprague

Subject: Pile force check for orthogonal load combinations
Date: Wed, 27 Jul 2011 14:38:17 -0500
From: Ravi.Vasu(--nospam--at)jacobs.com
To: seaint(--nospam--at)seaint.org

List,
In the design of non building structures like pipe rack in SDC D, we design the steel pipe rack
for orthogonal load comb. also. When we design the foundation, is there any exception that the fdn & piles
need not be checked for orthogonal load combinations? The ASCE 7-05, section 12.5.4 is
not clear about foundation check. It says about column or wall design in any direction.
(I am not sure about orthogonal condition check for column/wall)
Can anyone point to ASCE/IBC 2009 section about taking or not considering ortho load
Comb for fdn and Pile design?
Thanks

Ravi Vasu

 
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