Non-linear numerical modeling of reinforced concrete structures considering bond slip

Resumo

Depending on the stress magnitude in the interface of rebar and concrete, relative displacements may
develop. Thus, to develop a reliable numerical model, interaction between rebar and concrete must be included by
a bond slip constitutive relationship. Therefore, in this work we propose a numerical model to evaluate the bond
loss between reinforcement and concrete, based on the Positional Finite Element Method. In this method,
geometric nonlinearities are considered and static equilibrium are obtained though the Principle of Stationary
Potential Energy, considering total Lagrangian description. An incremental-iterative Newton-Raphson procedure
was used to solve the non-linear system. Fibers (rebars) are immersed in the matrix (concrete) though nodal
kinematic relationships, allowing mesh independency. Physical nonlinearity for concrete is considered by Mazars
damage model, and for reinforcement it is considered an elastoplastic constitutive relationship. Bond rupture is
simulated by Lagrange multipliers and relative displacement of matrix and fiber (slipping) is made up by a
dimensionless bonding element after rupture. Results are compared to experimental and analytical examples,
showing that the proposed method is reliable and accurate.