Insertion points on SAP2000...
Insertion points on SAP2000...
(OP)
By default when aplying insertion points in a frame to simulate diferent positions of gravity center, there is an option "Do not transform stiffness for offsets from centroid".
I'm trying to model a post-tensioned beam connected to a concrete slab (with shell element), considering equivalent loads to pre-strenght.
If i use the default option for the insertion point, although in the extrusion view, it shows the beam-shell system as a T beam, the behaviour is exactly equal to the beam-shell system as a + (gravity center of the rectangular beam coincident with the shell gravity center).
If I don't select the default option (pretending with this a transformation of the stiffness in order to obtain a more rigid system) then I obtain strange forces diagrams (M and N).
The question is, when doing this, those forces are related to what fibre in the section?
All this started because I wanted to model the difference of stiffness without having to use RIGID frames or constraints to connect the shell and the beam, because it gaive me strange behaviours. The option is to use the rectangular beam (with a magnified factor of the I33 moment of inercia) but I'm not sure if it simulates the right behaviour.
I'm trying to model a post-tensioned beam connected to a concrete slab (with shell element), considering equivalent loads to pre-strenght.
If i use the default option for the insertion point, although in the extrusion view, it shows the beam-shell system as a T beam, the behaviour is exactly equal to the beam-shell system as a + (gravity center of the rectangular beam coincident with the shell gravity center).
If I don't select the default option (pretending with this a transformation of the stiffness in order to obtain a more rigid system) then I obtain strange forces diagrams (M and N).
The question is, when doing this, those forces are related to what fibre in the section?
All this started because I wanted to model the difference of stiffness without having to use RIGID frames or constraints to connect the shell and the beam, because it gaive me strange behaviours. The option is to use the rectangular beam (with a magnified factor of the I33 moment of inercia) but I'm not sure if it simulates the right behaviour.
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RE: Insertion points on SAP2000...
It's my understanding that insertion points automatically create constraints based on which insertion point you choose (Top center, bottom right, etc, etc), so you're not avoiding the use of constraints by using insertion points.
Also, on the insertion point dialogue you can assign frame offsets from the cardinal point, typically moving both the I and J ends the same distance. If you have a nice orthogonal system, you can assign the frame offsets using Global instead of local coordinates which is sometimes easier to visualize