Performance assessment of a building with passive dampers using MIMO system identification

For the purpose of monitoring building behavior under earthquakes, a structural health monitoring (SHM) system was installed into a medium-height off-ice building in Tokyo. This building is equipped with passive energy dissipation devices, including Viscous vibration control walls and low yield point steel-based buckling restraint braces. As a SHM system, accelerometers were installed on several floors and strain sensors were glued to a few dampers on the sixth floor. When earthquakes occurred, observations are done and acceleration and strain data of each point of the building were obtained. With the data, MIMO system identification methods were applied to estimate dynamical behavior of the building. From collected observations of the last 4 years, the natural frequencies have shown a gradual decreasing tendency. Detailed discussions oil this phenomena is given in this paper.