P-Delta effects and the leaning column

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mohsenkh
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Joined: Wed Apr 21, 2010 7:40 am

P-Delta effects and the leaning column

Post by mohsenkh »

Dear

I modeled a 2-D steel frame, and considered the leaning column for P-Delta effects.

I have two questions:
1) Is total weight of each story considered as the load of the leaning column in each story?
2) What is combination load considered as the load of the leaning column in each story?

Best Regards;
fmk
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Re: P-Delta effects and the leaning column

Post by fmk »

1) if this is the only lateral resisting frame then yes, otherwise the load is the portion of the load this frame is responsible for.

2) ?? don' understand your question, could you rephrase it.
mohsenkh
Posts: 27
Joined: Wed Apr 21, 2010 7:40 am

Re: P-Delta effects and the leaning column

Post by mohsenkh »

Dear Dr Fmk

Thanks for your reply.

Is (Dead load + Live load) considered as the load of the leaning column in each story ? or other combination of Dead load and Live load?
amir70007
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Re: P-Delta effects and the leaning column

Post by amir70007 »

HI...

Do I need to define leaning column for P-Delta effects in my model If I use "PDelta Transformation" for "Geometric Transformation Command" ?
vesna
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Re: P-Delta effects and the leaning column

Post by vesna »

Leaning column is usually included in the model to capture the effect of gravity columns on the response of the lateral frame. For the leaning column to work properly you need to assign "PDelta" geometric transformation to it.
amir70007
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Re: P-Delta effects and the leaning column

Post by amir70007 »

Thank you...
1-According to your reply if the 3D model has no gravity column I do not need to define leaning column.

2-Suppose the model has 6 frame and the external frames are MRF and internal frames are gravity columns.
Is it correct that in a 2D model I assign gravity load of MRF frame to its own MR frame and assign gravity load of 2 other internal frames to the leaning column?

3-Do I need to assign "PDelta Transformation" to MRF columns too?
4-How can I calculate moment of inertia and area of a leaning column?
vesna
Posts: 3033
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Location: UC Berkeley

Re: P-Delta effects and the leaning column

Post by vesna »

1. Yes.

2. Yes.

3. Yes.

4. You can find it here: Gupta, A., and Krawinkler, H. (1999). "Seismic Demands for Performance Evaluation of Steel Moment Resisting Frame Structures," Technical Report 132, The John A. Blume Earthquake Engineering Research Center, Department of Civil Engineering, Stanford University, Stanford, CA. [electronic version: https://blume.stanford.edu/tech_reports]
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