[emadogail]

I am trying to model a reinforced concrete slab supported on the four edges . the load is applied on square plate of 150 mm side length in the centre of the slab . The edges of slab are expected to lift up during the test . So a contact element of zero tension capability is used to model the boundary condition between the slab and the supporting plates.
The actual young modulus from experimental test is set in the ABDL mechanical ANSYS which equal to 20810 MPa

After solving the problem and plotting the load - central deflection curve .. I found that the stiffness ( slope of the curve ) was greater than the experimental one .. the problem is solved by reducing young modulus to 0.25 the actual young modulus.
But the solution is not acceptable to get the real behaviour.

Please help how to overcome that problem ? .. what are the different solutions to decrease stiffness without decreasing the young modulus?