Study on nonlinear damping behavior of damaged recycled aggregate concrete beams

Abstract

AbstractAn experimental study on the nonlinear damping behavior of recycled aggregate concrete (RAC) beams is conducted through subjecting dynamic loadings at the different damage stages. The effects of the loading frequency, loading amplitude, damage, recycled aggregate, and replacement percentage on the energy dissipation by damping and the equivalent viscous damping ratio (EVDR) of the RAC beams are analyzed. The experimental results show that the energy dissipation and the EVDR are not directly influenced by the loading frequency, and the EVDR rises with the increasing loading amplitude for the damaged beams. The damage stage is of great significance to the damping mechanism. The EVDR is firstly increased, peaks at the yielding stage, and finally declines with the damage accumulation, and the EVDR at the yielding stage can be increased to 2.6–3.1 times compared to the undamaged RAC beams. The EVDRs are higher for the beams with the incorporation of the recycled aggregates, because of their lower stiffness and higher energy dissipation. The experimental results demonstrate that the commonly applied viscous damping model is not capable of correctly describing the damping behavior of RAC beams, whereas the modified Coulomb damping model performs much better. A shift in the damping mechanism is observed with the damage evolution, and the relationships between the damage indices and the damping parameters are established.