Capital and punching

Hi, I am doing a practical work for students , the goal is to teach the operation of a mezzanine without beams . I want to show how it works and how it works with capital without capital , to learn the concept of punching. The problem is that when I build the model notice no difference between the single column and the column with capital . How should build the column to display the punching and functioning of capital ?  

thank you very much  

best regards

Patricio

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TP1 Entrepiso sin vigas.gh, 61 KB

Replies to This Discussion

Permalink Reply by Karamba3D on February 16, 2015 at 8:43am

Hi Patricio,

connecting a beam to a shell in just one point creates a singularity: A point has no extension. The column pushes through the shell like a very thin but very strong needle. A singularity results. This means that the floor plate will think through the column. The more one refines the mesh the larger the resulting deflection. In order to avoid this, place short pieces of beams in the plate that simulate the extension of the column cross section or the capital. This could be an in-plane, crossed out beam rectangle.

The shear forces in the shells are normally not very accurate. They are proportional to the third order derivative of the deflection with respect to position. In Finite Element calculations the deflections are an approximation and even more so any higher order derivatives. In order to assess the effect of punching shear it is therefore better to use the difference of normal forces in the column below and above the floor.

Best,

Clemens

Permalink Reply by Llordella Patricio on March 2, 2015 at 7:07am