How to trigger stiffness degradation earlier?

[compe_ad]

Hi everyone!
I am working on ABAQUS model which consists of a reinforced concrete wall and has a cantilevered W-shaped steel beam embedded (see attached picture). In order to make it computationally efficient, I am modeling just half of the full-size specimen. The steel beam is subjected to a cyclic shear loading whereas the wall has its base fixed. I have built the model and am trying to match the output with the experimental results. I am defining a cohesive interaction between steel beam and concrete with following properties:
*Kn=0, Ks=Kt=28
*Normal stress=0, Shear stress along s and t direction=0.42 ksi
*Plastic displacement=0.1 in.
Looks like my ABAQUS model is capturing the failure point well (i.e., connection also failed at the same cycle as seen in experiment) however, the way of connection degradation happening seems to be bit off (refer to attached graph). Connection degradation is starting later in my ABAQUS model as compared to experiment. Can anyone please suggest me what parameters might be contributing to this result?
Thank you in advance.

 

[FEA way]

Try adjusting the damage initiation and evolution parameters. You may also consider using cohesive elements instead of cohesive contact but maybe damage parameter tweaking will be sufficient.

 

[compe_ad]

Thank you for the response.
Can you please tell me why you are suggesting cohesive elements? What will be the difference between modeling with cohesive interaction versus cohesive elements?

 

[FEA way]

Check the following documentation chapter: Interactions --> Contact Property Models --> Mechanical Contact Properties --> Contact Cohesive Behavior (paragraph "High-Level Comparison of Cohesive-Element and Cohesive-Contact Approaches").

In short words, cohesive contact is easier to use but cohesive elements give you more advanced options (e.g. more types of constitutive behavior) and are recommended for more detailed adhesive modeling.