What is the primary function of energy dissipation devices, such as viscous dampers, in a seismically retrofitted structure?

The primary function of energy dissipation devices, such as viscous dampers, in a seismically retrofitted structure is to reduce the structure's response to earthquake ground motions by absorbing and dissipating a portion of the seismic energy input. These devices achieve this by converting the kinetic energy of the building's motion into heat, which is then dissipated into the environment. By reducing the amount of energy that the structure must withstand, energy dissipation devices can decrease the magnitude of forces and deformations in the structural elements, such as beams, columns, and walls. This, in turn, reduces the likelihood of damage or failure, improving the overall seismic performance of the building. Viscous dampers, for example, resist motion proportionally to velocity, providing damping forces that help to control the building's vibrations and prevent excessive swaying during an earthquake. The use of energy dissipation devices allows for a more controlled and predictable seismic response, enhancing the structure's ability to withstand earthquake forces and protect its occupants.