Structure analize

Grasshopper Karamba3D
1

hi every one
i have a tall building structure and would to do structural analysis with karamba but the results of displacement seems incorrect. by analyze component, displacements are high and by analyze nonlinear WIP component, displacements are too low. i read the manual but i did not understand difference between these two components.
on the other hand when i connect joints to assemble model analize component show errors.
can every one help with these two problems?

2

Hi @sepideshoaee,
if you can share the definition we would be able to assist you to see what is happening in the calculation.
best,
Matthew

3

thanks for your reply. I used both of the Analyze ThI and Analyze Nonlinear component for obtaining displacements but for analyze Th1 results are high and for WIP results are low values.i read the manual but i did not understand the difference.can you help me with this?

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4

Dear Sepideshoaee,
there can be two reasons why a geometric non-linear calculation in Karamba3D 1.3.1 returns lower displacement values than the linear calculation:

  1. A geometric non-linear calculation takes into account the change of length of the elements in case of lateral deflection. This can have a stiffening effect - think of e.g. a rope with a point-load in the middle which is initially straight and spans between two fixed supports.

  2. In its current state (Karamba3D 1.3.1) the component for geometric non-linear analysis is still work in progress (WIP). It could be that the calculation did not converge at a certain load increment. In order to check this have a look at the output of ‘Lambdas’. There you see which load-factors have been reached.
    Best,
    Clemens

5

Thanks for your reply.it helped me but I did not understand what does which load factors have been reached means? I extracted lambdas and info information in the following picture.

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6

i have two two other questions.

  • i have two types of elements that i defined ID for them. one is related to perimeter structure and the other is related to floor structure.i inputted them to assemble model.will be assemble model consider these two types of elements connected to each other or not? when i define joints for these two parts, displacements increase significantly.
  • my structure is completely symmetric but the center of gravity is not in the center of plan.do you think this may be the reason of high displacement in linear analyze?
    thanks.
7

When you do a non-linear analysis the load gets incremented in steps. The lambda values are the load-multipliers. The last value ‘0.4…’ means that 40% of the loads are applied to the structure. Please read the manual for details.
Best,
Clemens

8

ad 1.) In Karamba3D elements are connected if they share a common node.
ad 2.) That the center of gravity if off the center of a symmetric structure indicates a problem in the definition. You could check whether the mass which is output at the ‘Assemble’-component is correct.
Best,
Clemens

9

thanks for your reply