Discussion Groups

Robot Structural Analysis

Reply
Mentor
GabrieleNovembri1027
Posts: 162
Registered: ‎01-24-2009

Plastic Hinges - Plate shell ?

455 Views, 3 Replies
03-24-2012 03:27 AM

Hi All,

according to Robot help seem possible to define plastic hinges to shell elements (?). May I have more information about the topic reported by the manual ?

see attached picture

 

shell push over.PNG

 

Please use plain text.
Product Support
pp2008
Posts: 472
Registered: ‎06-23-2008

Re: Plastic Hinges - Plate shell ?

03-25-2012 11:44 PM in reply to: GabrieleNovembri1027

Hi Gabriele,

the main Help topic of this feature states:

"Non-linear Hinges

This option is used for defining and assigning non-linear hinges to structure bars. (...)"

 

The part of Help you have mentioned discuss only the scope of availability of this feature for various types of structure and available degrees of freedom.

 

---------------------------------------------
If this post answer your question please click "Accept as Solution". It will help everyone to find answer more quickly!

 

Regards,



Pawel Pulak
Please use plain text.
Mentor
GabrieleNovembri1027
Posts: 162
Registered: ‎01-24-2009

Re: Plastic Hinges - Plate shell ?

03-26-2012 05:46 AM in reply to: pp2008

Hi Pawel,

I understand that no plastic hinges are available for plate-shell element. It seems to me that the help is quite confusing because under "New Non-linear Hinge Type" topic describes several types of hinges including plate shell element and so on. In this context the statement "Depending on the type of structure only some hinge types are available, similar to bar releases. The description in the Type: stress-strain field changes depending on the type of structure and the available degrees of freedom"   seems to me quite confusing because it refers also to plate shell elements, solids, Plane stress structure, Plane deformation structure and Axisymmetric structure.

Anyway, my problem is that I am trying to use robot to calculate a masonry wall structure. If I well understand Robot don't support plasticity for plate shell elements like Mohr-Coulomb, Drucker-Prager or Strumas. In this case the approach that you can take in order to make a non linear analysis of such type of structure is the column beam analogy with plasticity concentrated in plastic hinges.

Also in this case you have some limitations. Only for steel (it seems) the plastic hinge can be expressed in terms of ratio between the current value and the limit value. For other materials than steel, if I well understand, you have to define the limit value that, unfortunately, changes with the Fx acting on the bar.

Do you have any suggestion regarding the approach to take in modeling masonry wall structures ?

Thanks

Please use plain text.
Product Support
pp2008
Posts: 472
Registered: ‎06-23-2008

Re: Plastic Hinges - Plate shell ?

03-26-2012 06:23 AM in reply to: GabrieleNovembri1027

Hi Gabriele,

1/ The statement in Help is referring to available degrees which can be used in bar hinges and which depend on degrees of freedom available for appropriate  structure type. Degrees of freedom available for 3D Frame, Shell, Solid and Building Design are UX, UY, UZ, RX, RY, RZ - i.e, all  translations and rotations.

That is why bar hinges can use for these types of structure Sx(FX, MY, MZ)  - i.e. normal force FX and bi-directional bending (MY, MZ) is considered.

 

2/ Unfortunately  as it is stated in Help the interaction between different degrees of freedom is disregarded. For eample bending of a bar in one plane does not depend on bending in another plane and longitudinal forces.

As for now such functionality is not available.

 

Regards,



Pawel Pulak
Please use plain text.