I encounter a problem when I simulate a pullout test of steel reinforcement from a concrete prism.  I deal with this problem as a plane stress problem and use truss element to model the steel reinforcement, for which the bond behavior have been defined. For this problem, the external forced should apply on the edge joint of the reinforcement. But, it is impossible to apply the force. When I apply the force on the same joint (shared with the edge joint of steel reinforcement) of concrete, I found that the force distribution in the steel reinforcement is unreasonable. So, I guess that the force acctually is not applied on the steel reinforcement. If anyone get to know this problem, please dome a favor. Thank you so much.