Hi all, I am simulating a Timber-Concrete Composite under push-out test. I have got results that are very close to the experimental one and have tried to modify the boundary condition, interaction between parts, material properties to bring my result closer to the experimental one (the red curve). However, all adjustment did not help. 

I am now at a stage that I have tested all possible adjustment I could think of but still could not figure out a way to get more accurate result. I would like to know, given my results in the plot, what parameter in the analysis tab should I look into to discover the potential cause of the over-estimation in ultimate strength of the composite? Thanks!