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Axial force stress check of column in SAP2000
2

Axial force stress check of column in SAP2000

Axial force stress check of column in SAP2000

(OP)
Hi everyone
So I'm getting an overstress error for a column in SAP2000 and when I check the data I have:
STRESS CHECK FORCES & MOMENTS (Combo UEY-03)
(ASCE 12.4.3.2(5): (1.2+0.2*Sds)*D + 1.0*L + Omega0*Qe)
Location Pu Mu33 Mu22 Vu2 Vu3 Tu
0/07 -12255/988 107/05 37/222 0/ 0/ 0/008

so that means I have an axial force of -12255 with the defined load combination of UEY-03 right?
but then a few lines down under, I get this:

AXIAL FORCE & BIAXIAL MOMENT DESIGN (H1-1a)
Factor L K1 K2 B1 B2 Cm
Major Bending 0/932 1/ 1/ 1/ 1/ 0/385
Minor Bending 0/932 1/ 1/ 1/ 1/ 0/292

Lltb Kltb Cb
LTB 0/932 1/ 2/181

Pu phi*Pnc phi*Pnt
Force Capacity Capacity
Axial -33108/499 31733/491 61560/

If I'm understanding right this suggests that the column has a capacity of 31733 ,but the axial force is as much as -33108? but how? what do phi*pnc and phi*pnt means? how did PU jump from -12255 to -33108?

RE: Axial force stress check of column in SAP2000

If you do not know what phi Pc and phi Pnt then you have absolutely no business using this software for design checks. These are the code determined adjusted strength in compression and tension of the column. Sorry to be brash but really if you don't know what these mean or how to determine them by hand then you cannot trust the results of the computer and you certainty should not be using this computer model to design a real structure.

RE: Axial force stress check of column in SAP2000

These values are determined based on the concrete section properties, reinforcement, and material properties, they are defined by the prevailing building code that is set in sap2000. It is a good idea to verify that computer design results are accurate and consistent with what is expected. I can recommend this text book to help understand and derive the design values you have questioned. Link. And I'm sorry my response was not suitable to you, but you must understand that engineering of this sort involves safety of human life, without the background context of your question it appears rather dangerous that a structural engineer is asking what these terms mean.

RE: Axial force stress check of column in SAP2000

I don't think he was being a "dick". Just expressing concern. Though his tone certainly comes off a little too "judgmental" when I read it. Hopefully, you're just looking at an example that's based on a design code you're not familiar with.

For the USA (and I think the Australian / New Zealanders and probably Canada as well) Phi*Pc and Phi*Pt are pretty much the two most basic terms:
Phi is a safety factor (which can vary depending on where it's used).
Pc is the nominal design strength of the member in compression.
Pt is the nominal design strength of the member in tension.

So, if you are in the US or just doing a project based on US codes it's a nearly unforgivable error to not understand these terms. Combine that with some US engineer's frustrations over having project shipped overseas and his tone becomes a little more understandable.

RE: Axial force stress check of column in SAP2000

(OP)
Thanks for the responses. I believe the basis of this conflict is that you've presumed a lot of things without realizing how vastly different the possibilities can be. I don't design structures, I work as a quality control engineer on an EPC project in the middle east, and things are really different here. I did calculate the column capacity by hand and it was different. That's why I asked the question in the first place. we have a slightly different design code and the designer was using US because SAP2000 doesn't cover ours. I'm sorry the question was so silly to you.

RE: Axial force stress check of column in SAP2000

Haamed -

You don't need to apologize to me or driftlimiter. I just wanted to point out why you may have gotten a "less cordial" response than you expected.

Eng-Tips is really a great tool to engineers everywhere. But, sometimes you will get responses to questions when someone thinks a student is asking questions they should ask their professors, or when a non-engineer is asking questions that they should be running by their engineer first.

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