Modeling of smart concrete beams with shape memory alloy actuators

• An effective procedure for the analysis of reinforced concrete beams with SMA actuators for cracks repair is presented.
• Nonlinear nonlocal damage–plasticity model with microcrack–macrocrack transition is proposed for the concrete.
• An uniaxial SMA model is adopted to reproduce the pseudo-elastic and the shape memory effects.
• A finite element procedure able to solve the highly nonlinear problem is developed.
• Comparisons with experimental evidences are illustrated.

In the present work, a computational strategy for the modeling of reinforced concrete beams with SMA actuators for cracks repair is developed. In particular, for the concrete, an original transition damage–fracture technique is proposed in order to simulate the microcrack arising, their coalescence and, finally, the macrocrack development. Microcracks are modeled adopting a nonlocal damage and plasticity approach, which is able to consider the tensile and compressive damaging, accumulation of irreversible strains and the unilateral phenomenon. Macrocracks are modeled using a cohesive zone interface which accounts for the mode I, mode II and mixed mode of damage, the unilateral contact and the friction effects. The interface models the transition from the continuum damage (simulating the presence of microcracks) to fracture. A uniaxial SMA model able to reproduce both the pseudo-elastic behavior and the shape memory effect is adopted for the reinforcing SMA bars.Finite element simulations are developed in order to reproduce the behavior of smart concrete beams subjected to three-point bending experimental tests available in literature (Kuang and Ou, 2008, Daghia et al., 2011). The construction phases of the beam are simulated and the loading history, consisting in three-point bending tests, are reproduced; in particular, the repairing phase due to pseudo-elastic behavior and shape memory effect is reproduced. Numerical results are compared with experimental data to validate the computational strategy.