Negative eigen values error

[Ali asger]

Hello there , I am modelling a composite slab as SIF 1 i have provide surface to surface contact between steel and concrete and boundary conditions i have applied using a rigid body tie constrain to a reference points and loading i have used coupling to a reference point and applied a point displacement of 15mm , my problem is my model is taking too much time , further it is getting aborted and most common warning i am getting is of negative eigen values and when i am comparing my model to an actual experimental data the initial stiffness is not matching correctly please help me regarding above mentioned issues.


Thankyou

 

[FEA way]

Can you share the file (.inp or better .cae) ? It's hard to say without seeing the details.

 

[Ali asger]

Please check model-1 and please help me fixing its initial stiffness , i am validating my model with a research paper , i am attaching its graph please check it


Thankyou