Experimental study on relationship between damping capacity and damage degree of recycled concrete cantilever beam

The damping capacity of recycled concrete members at inelastic stage mostly depends on the damage degree. Taking the recycled coarse aggregate replacement ratio and size distribution as controlling factors, the pseudo-static test and free vibration damping test were conducted to study the damping capacity of cantilever beams damaged at different levels. The influence of crack development on damping and damage evaluation were also discussed and the quantitative relationship between damping ratio and damage index of cantilever beam was built. The test results show that the damping ratio of recycled concrete cantilever beam first sharply increases and then decreases with the damage index. The peak damping ratio is about 2 times that at elastic stage. For the same damage index, the damping ratio increases with the coarse aggregate replacement ratio, while decreases with the aggregate size. The physical and mechanical properties of recycled aggregate, replacement ratio and size distribution all have significant impacts on the damping ratio and damage index of recycled concrete member. The evolution of damping capacity and damage index of recycled concrete member is related to the crack number, density and length.