As far as I can see Robot starts to have difficulty to converge the last of many non-linear cases for the BFGS method and the multi-threaded solver (when you restart calculations or delete some of the previous cases then divergent cases will converge). Thank you for pointing this situation out - we will check what exactly happens.
Corrected in Robot 2015.
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I think ( still testing) I found a way to do it using non-linear bar releases .
Structure to the left - panels are normally connected
Structure to the right - Exact same structure ,(with same load ,10tf/m2 on the top slab area) except that the vertical panel is 2cm shorter . Mesh is 1 mt . Created very stiff bars (2cm) connecting the panels at each node. Then I created a non-linear release limiting the moment at 25tf.m(12.5tf.m on the sides) using " rigid with linear hardening" type. Seems to be working nicely. For a load that does not reach 25tf.m on that edge , both structures show the same bending moment. Is there anything else that I should be aware?
Structural + Detailing engineers
I used the 20mm bars as rigid links. I didn't show the panel moment maps but they are perfectly normal with no spike moments values. I thought about compatible nodes but I think they can only be used with bars.
I thought about compatible nodes but I think they can only be used with bars.
It is the only way you can define (or shall i wrote control to which object they are assigned) them but you may achieve this goal in the following way:
1. Define compatible nodes (with the intended nonlinear function) at the intersections of bars created at the intended location of a common edges of panels.
2. Delete bars
3. Move one of the set of nodes either vertically or horizontally
4. Define panels with (temporarily separated) edges at the lines of these nodes and mesh them (make sure the generated meshes match number of nodes along the edges)
5. Freeze meshes
6. Move the 'shifted' nodes (as well as the panel's edge if you want) to their 'original' locations