Yield Line Implementation

[Son_new]

Dear All,

How is the procedure of determining the yield lines in the arbitrarily shaped plates/shells. In order to find the yield iso-lines may I assume that moment that exceeds the plastic capacity of section is one of the point on the yield lines?

My intention to find the yield lines is to determine the loads transfered on the beams  from slabs.

Regards,

[FEAP_Admin]

I suggest you head to the library and look at book on slab design;  or search google-books for yield line theory.

[Son_new]

I have done it already,

Actually my point of interest is on how load transfering from slabs to beams can be calculated with FEM.
I'm already familiar with virtual work method and equilibrium method with yield line analysis but that doesn't give me any clue on how that can be implemented especially with FEM. I have many books( Plates Theory and Applications . Szilgard)  and nomenclatures (e.g. Jones , Bauer etc..) regarding that subject, the difficulty is that, yield line analysis has taken completely the different approach such as deflections are only on the yield lines, yield line might include the local nodal and line loads but doesn't take into account the different UDLs scattered arbitrarily over the slab. 

It seems that YL is only for general estimation of yield lines, what I need is exact solution for any distinctive loading and I'm unsure that can be can be achieved with the YL analysis. There should be a some way to implement that with plate and shell elements but don't know from where to start and I need a guidance.

Your help will be appreciated.

[FEAP_Admin]

Yes, YL theory is for estimation (upper bound theory of plasticity, see for example Washizu).
In FEA what you want is a plate element with an elasto-plastic material law.  This will then predict
progressive section yield.  In the limit of infinite curvatures this will give a result similar to the YL result (if
you have picked your yield lines well).