Proposing an RC Fiber Frame Element Based on Local Stress Field Theory and Bar-Concrete Interaction

This research presents an analytical model for developing a fiber frame element based on local stress field theory. The proposed formulation is developed through the Lagrangian kinematics assumption to derive the weak form of the equations in large strain conditions. In this regard, the effect of bond-slip has been considered by removing the perfect bond assumption. The governing equations for each element are developed by the directional stiffness matrix in weak form. The extracted formula is based on Timoshenko's beam theory, with axial, bending, and shear interaction effects in the domain of each element. The components of the stiffness matrix are defined through directional derivatives of the semi-linear form of the equations. Moreover, the suggested approach evolves from cubic Hermitian polynomials and the local stress field theory. The validation of the analytical method is provided by the available experimental tests. The implemented code could cover the overall behavior of reinforced concrete members, as well as, the maximum crack width, slip profile, and crack growth. The results show that such a modeling method is capable of simulating RC members.