Study on nonlinear damping behavior of damaged recycled aggregate concrete beams

Abstract

An 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.

Early‐age behavior and mechanical properties of cement‐based materials with various types and fineness of recycled powder

“…Therefore, the reclamation technology of concrete waste has been developed, where concrete waste is commonly crushed into recycled aggregate and reutilized in newmade concrete 5 . Because of the inferior properties of recycled aggregate relative to natural aggregate, substituting recycled aggregate for natural aggregate in concrete is detrimental to the drying shrinkage, 6,7 long‐term durability performance, 8,9 and mechanical properties 10–12 . Although the application of nanoparticle incorporation, carbonation modification, physical and chemical enhancement contributes to improve the properties of recycled aggregate, the improvement efficiency and economic benefits are not satisfactory for large‐scale production of recycled aggregate with high quality 13–15 .…”

“…5 Because of the inferior properties of recycled aggregate relative to natural aggregate, substituting recycled aggregate for natural aggregate in concrete is detrimental to the drying shrinkage, 6,7 long-term durability performance, 8,9 and mechanical properties. [10][11][12] Although the application of nanoparticle incorporation, carbonation modification, physical and chemical enhancement contributes to improve the properties of recycled aggregate, the improvement efficiency and economic benefits are not satisfactory for large-scale production of recycled aggregate with high quality. [13][14][15] Therefore, researchers around the world put forward a new technology method of reclaiming construction and demolition waste into active recycled powder (RP) as an alternative binder or supplementary cementitious material (SCM), and the utilized RP (<0.15 mm) in new cement-based materials reduces the dosage of cement, which is cost-effective and eco-friendly.…”

Performance Assessment of an Energy–Based Approximation Method for the Dynamic Capacity of RC Frames Subjected to Sudden Column Removal Scenarios

“…Therefore, the maximum deflection response will be overestimated. Moreover, it is still a controversial issue regarding how to model the damping mechanism for a sudden column removal scenario [19,47,48], e.g., viscous damping or Coulomb damping [23]. For instance, the studies have identified drawbacks associated with the use of Rayleigh damping based on initial stiffness, in which the initial stiffness may introduce in the unwanted artificial viscous forces [14,49].…”