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.

中文翻译：

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破损再生骨料混凝土梁非线性阻尼行为研究

通过在不同损伤阶段承受动态载荷，对再生骨料混凝土 (RAC) 梁的非线性阻尼行为进行了实验研究。分析了加载频率、加载幅度、损伤、再生骨料和替代百分比对 RAC 梁的阻尼耗能和等效粘滞阻尼比 (EVDR) 的影响。实验结果表明，能量耗散和EVDR不受加载频率的直接影响，EVDR随着损坏梁加载幅度的增加而增加。损伤阶段对阻尼机制具有重要意义。EVDR先增加，在屈服阶段达到峰值，最后随着损伤的积累而下降，屈服阶段的EVDR可以提高到2.6-3。1 倍与未损坏的 RAC 梁相比。加入再生骨料的梁的 EVDR 更高，因为它们的刚度较低，能量耗散较高。实验结果表明，常用的粘性阻尼模型不能正确描述 RAC 梁的阻尼行为，而改进的库仑阻尼模型表现更好。随着损伤演化观察到阻尼机制的变化，并建立了损伤指数和阻尼参数之间的关系。实验结果表明，常用的粘性阻尼模型不能正确描述 RAC 梁的阻尼行为，而改进的库仑阻尼模型表现更好。随着损伤演化观察到阻尼机制的变化，并建立了损伤指数和阻尼参数之间的关系。实验结果表明，常用的粘性阻尼模型不能正确描述 RAC 梁的阻尼行为，而改进的库仑阻尼模型表现更好。随着损伤演化观察到阻尼机制的变化，并建立了损伤指数和阻尼参数之间的关系。