element local forces Vs. Section Forces

Forum for OpenSees users to post questions, comments, etc. on the use of the OpenSees interpreter, OpenSees.exe

Moderators: silvia, selimgunay, Moderators

Post Reply
civily
Posts: 13
Joined: Wed Mar 26, 2008 7:57 pm
Location: Auburn

element local forces Vs. Section Forces

Post by civily »

Hi all,

I am conducting a large deflection analysis and using NL beam-column element.I have a couple questions regarding element forces;

1) Is the element local coordinate system based on deformed or undeformed configuration,in other words,for instance;is local Fx in the direction of element chord?..

2) Similar question for section forces;are they calculated by integrating the section deformations or is it a transformation issue?..Again,is sectional N in the direction of element chord or is it perpendicular to cross-sectional plane?..(Because the chord is not necessarily perpendicular to it)...I guess if they indeed are calculated by integration,N needs to be perpendicular to the c-sectional plane...

I compared both local forces and section forces for a specific element end and came up with Sectional N=Local Fx...It seems like Sectional N is in element chord direction,not perpendicular to c-sect. plane...

I'd appreciate if someone clarify this for me,my observation kind of gave me an idea but I still wanted to make sure...

Thanks,
silvia
Posts: 3909
Joined: Tue Jan 11, 2005 7:44 am
Location: Degenkolb Engineers
Contact:

Post by silvia »

in Linear transformation, undeformed configuration, unless you do the corotational transformation, then it might be different.
Silvia Mazzoni, PhD
Structural Consultant
Degenkolb Engineers
235 Montgomery Street, Suite 500
San Francisco, CA. 94104
civily
Posts: 13
Joined: Wed Mar 26, 2008 7:57 pm
Location: Auburn

Post by civily »

thanks for reply,I'm sorry I should have specified that.But it's large deflection problem so,I'm using corotational transformation...

I'd appreciate your help..
civily
Posts: 13
Joined: Wed Mar 26, 2008 7:57 pm
Location: Auburn

Post by civily »

Could anyone please clarify this issue?
Post Reply