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4

Dear Irene, do you mean A. the convergence in teh sense of the convergence errors in each step, or B. the global convergence - i.e., as referred in the basic convergence theorem (general for partial differential equation) that approximation + stability gives convergence = approximation of the solution getting closer with mesh refinement? Or something else?

If A., the absolute mesh size is not as important as other factors, like the finite element shapes. If B., I can only rephrase the previous answer: a finer mesh should give results closer to the exact solution of the equations, however, of course getting closer than the errors made in the assumptions applied when fomulating the equatons (e.g., concrete as a homogeneous continuum), has no sense.

3

What about in terms of convergence? will it produce a good convergence result?

In the example, only 1 mesh size is shown, which is 0.025 m. Do you think for a better convergence (until negligible) the mesh size should be selected?


Do you think is necessary to try other element size of 0.02, 0.03, 0.035, 0.04 to see the difference of results produce?

tq

2

Hello Irene, there is no general "best element size". The optimal mesh size and refinement location(s) strongly depend on the structure and loading being modelled, and also on element type. For example in bending regions you need enough elements per the beam height/plate thickness when using volume elements, but a single shell with a few internal layers works well. When reducing the element size one should also consider that for elements comparable to aggregate size (or smaller), the basic assumption of modelling concrete as continuum becomes questionable (at least unless the spatial heterogenity is represented by random fields).

1

Hello,

In the ATENA 2D Example Manual under Leonhardt's beam, the element size used was 0.025 m (for quadrilateral) in the example. Is this mesh size give the best convergence results for various RC beam problems?

TQ

Cervenka Consulting Forums → ATENA → Element size → Post new reply