i make FEA for my master research in ANSYS PRO., i simulate a prestressed concrete beam with two precast units connected by contact element (CONTA.52). i used solid 65 for concrete modelling and link 8 for for prestressing steel with initial strain, i entered the stress strain curve for the concrete with linear isotropic, concrete and multilinear isotropic in five points as below:
strain=0.0004 stress = 12 Mpa
Strain = 0.001 stress = 30 Mpa
Strain = 0.0015 stress=37.5 Mpa
strain =0.002 stress = 40 Mpa
strain = 0.0003 stress = 40 MPa
i applied the load up to failure, then, i found that at the contact area, the strain =0.003 but the stress = 34 Mpa, however from the stress strain curve which i entered it must be = 40 Mpa.
i tried to change the stress strain curve to be the fc'=60 Mpa (just as a trial). and i applied the same load, i found that the strain at that load = 0.007 but the stress still = 34 Mpa at the same node
i hope if someone could help me to pass this problem
thanks