base shear and storey shear

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sama
Posts: 21
Joined: Sat Mar 05, 2011 11:46 pm
Location: Iran

base shear and storey shear

Post by sama »

hi
i have done some transient analysis on sac-9 model
and now i want to get the storey shears at each time step
should i use node reaction recorder?
i used that but the results doesnt seem rational
could you please help me on this?
thanks in advance
vesna
Posts: 3033
Joined: Tue May 23, 2006 11:23 am
Location: UC Berkeley

Re: base shear and storey shear

Post by vesna »

To get shear of one element you have to record element forces. To get a storey shear sum up shear forces from all elements at one level.
sama
Posts: 21
Joined: Sat Mar 05, 2011 11:46 pm
Location: Iran

Re: base shear and storey shear

Post by sama »

thanx vesna
i did so
but still i have question
i used global force as below

recorder Element -file $pfile1002 -time -ele 2 globalForce;

it will recrod some values as follow

0.02 -0.000209036 -0.000221235 0.000429146 0.000209036 0.000221235 0.000398637
what does it mean
is it
time fx fy fz mrx mry mrz
?
my model is two dimentional and has 3degree of freedom
vesna
Posts: 3033
Joined: Tue May 23, 2006 11:23 am
Location: UC Berkeley

Re: base shear and storey shear

Post by vesna »

These are forces of the element at nodes i and j. The first three forces are for node i and the last three are for node j. To see what each column stands for record the global forces in -xml format instead of -file format.

e.g.,
recorder Element -xml $pfile1002 -time -ele 2 globalForce;
sama
Posts: 21
Joined: Sat Mar 05, 2011 11:46 pm
Location: Iran

Re: base shear and storey shear

Post by sama »

Dear Vesna,
I have modeled a 3D bracing structure, and I got the foloowing warrning,

ForceBeamColumn3d::ForceBeamColumn3d-- no torsion detected in sections continuing with element torsional stiffness GJ/L=1e010,

what does it mean? and how should I solve it?

also it must be metioned that I have defined section aggregator as folows,
set G 7842000000
BOXsection 10 1 0.450 0.45 0.0190 0.019 12 4 12 4
set J 0.001521
set GJ [expr $G*$J ]
uniaxialMaterial Elastic 10 $GJ; # Define torsional stiffness

section Aggregator 1 10 T -section 10; # attach torsion and flexure

I havent assigne section aggregator for beams and bracings? does it occur because of that?
tanx in advance
vesna
Posts: 3033
Joined: Tue May 23, 2006 11:23 am
Location: UC Berkeley

Re: base shear and storey shear

Post by vesna »

3D elements need to have torsion assigned to their section. If you did not assign torsion to all of your 3D elements that is the reason for seeing the message.
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