Experimental characterization and modeling of energy dissipation in reinforced concrete beams subjected to cyclic loading

The way of modeling the damping phenomenon in nonlinear time history analysis is still an opened question and remains a motivating challenge in the scientific community. The well-known approach lies in considering non-physical viscous forces that are proportional to the velocity field. A damping matrix must be defined and its identification is not based on physical considerations. This study aims at exploring the possibility of identifying a local constitutive model in order to account for damping in a natural way. To reach this objective, an experimental campaign based on reinforced concrete beams subjected to reverse three-point bending tests is presented. These results allow identifying in an accurate way the hysteretic scheme used to take into account the hysteretic phenomenon. In particular, an ad hoc hysteretic scheme is shown to be consistent in terms of energy dissipation. Numerical free vibration tests are then carried out in order to demonstrate that the use of a viscous damping can be avoided if the local constitutive concrete model accounting for hysteretic phenomenon is accurately identified.