At the start of yielding, the equiv

At the start of yielding, the equivalent viscous damping coefficient of each joint increased with the loading displacement. As yielding began, the plasticity of the beam developed rapidly, and the energy dissipation increased. The equivalent viscous damping coefficient had only slight fluctuations in the displacement from 20 mm to the peak displacement. The local damage of concrete lowered the energy dissipation beyond 20 mm of displacement. However, the plasticity of the joint had room for development. The plasticity development and concrete damage were in a dynamic equilibrium that caused this stable portion of the coefficient. The coefficient tended to decrease slowly after the peak load was reached. After the peak load, part of the concrete was destroyed, and the energy dissipation of the joint was reduced.