panel issues in large model

[rtZSCC9]

Hi

I'm modelling a large structure - it's a slightly irregular shape but comprises steel frames with conrete/comflor type deck with cores for lateral stability.

As the model needs to be submitted for earthquake approval in China I've been asked to model the structure holistically i.e. with the basements and surrounding carparks. This has made for a very large model with a lot of panels for the core walls and floor slabs.

I've modelled all vertical walls as shear walls (shells) and I was trying to model the floor slabs as daiphragms as these only need to transfer the loads into the steel frame and provide horizontal stiffness. When I run the model like this ROBOT is forced to close (ROBOT has encountered a problem and forced to close). I cannot complete the analysis. Is there anything way I could model this more effiicently? 

i.e.

Core walls - I need to represent stiffness and be able to see the stresses in them

Slabs - Only required as diaphrams and to distribute UDL's into the supporting steelwork.

Thanks in advance

Kind regards

Richard

[Rafal.Gaweda]

File please.