localForce vs globalForce recorder

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Akbar
Posts: 6
Joined: Fri Mar 11, 2011 4:54 pm

localForce vs globalForce recorder

Post by Akbar »

Hello,

I was wondering what is difference between localForce and globalForce recorders for a forcebeamcolumn element? I am recording localForce and globalForce for an element part of a single steel column loaded under lateral displacement (with large P-Delta effect). When I comparing the recorder results for a given element, the shear force recorded in localForce recorder is larger than that recorded in globalForce recorder. It seems that large P-Delta effect is not included in the localForce recorder. Is that correct?

Any advice would be really appreciated.

Akbar
fmk
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Re: localForce vs globalForce recorder

Post by fmk »

you have it correct.

the elements work in a basic system (simply supported beam with 1 end a rollar). For the 2d beams, an axial force and two end moments are the basic element forces stored by the elemets. the forces computed when asked for the localForces just use the element length to compute the missing shear forces from the moments.

for the global forces the elements ask the geometric transformation to compute the forces base on the basic forces. It is here for exampe that the PDelta forces would be added.
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