Cracking Analysis of RC Members by Using Coupled BE-FE Modeling

The response of reinforced concrete members under uniaxial tension is investigated by an analysis model alternative to that based on the usual discretization of concrete and steel into tridimensional axisymmetric finite elements. The concrete behavior is modeled by boundary elements for plane strain problems in elasticity; the reinforcing steel bar is divided into two-node finite elements, opportunely defined. A nonlinear local bond stress-slip law is assumed, and it is specialized in a different way according to whether the response of an uncracked member is analyzed, or postcracking behavior is considered, in which case change of sign in slip occurs at the steel-concrete interface region near the crack. The proposed procedure allows one to determine the bond stress and slip redistributions consequent to cracking simply by modifying the original boundary and geometrical conditions of the model and taking into account the bond stress and slip distributions at the stage of incipient cracking. Therefore, the computational effort of a step-by-step analysis is avoided, contrary to the case of finite-element modeling using special “contact elements” at the interface. The reliability of the proposed approach is shown by comparing the results with those obtained by other authors using the finite-element method (FEM).