Abstract: A high damping device combined with the frame of a building to protect the building from seismic shock. For seismic vibration up to a predetermined level corresponding to the permissible strength of the high damping device, a damping coefficient c of the high damping device is set so as to be c.sub.3 =c=c.sub.1 with respect to a damping coefficient c.sub.3 for giving the maximum value of a damping factor h.sub.3 corresponding to a tertiary mode of vibration of the structure and a damping coefficient c.sub.1 for giving the maximum value of a damping factor h.sub.1 corresponding to a primary mode of vibration. The maximum load on the high damping device is predetermined and means are provided to prevent the high damping device from being damaged in the event that the predetermined maximum load is exceeded. The inventive combination permits the stiffness factor of the building to be reduced from a factor of 1.0 down to a factor as low as 0.3, with a proportionate reduction in steel frame mass.

Abstract: An active seismic response control system includes a variable damping device provided between posts, beams and braces of a structure, wherein the response of the frame is reduced by controlling the variable damping device when an earthquake or strong wind occurs to give a damping force to the frame. The response of the structure is determined by the steps of judging with a computer the optimal damping force or control force to be applied to the structure on the basis of information obtained from sensors in response to the disturbance, and then controlling the coefficient of damping of the variable damping device.

Abstract: A variable damping and stiffness structure is disclosed, which includes a variable damping device provided between posts, beams and braces of a structure or braces serving as variable stiffness elements and interconnecting a frame body and the variable stiffness element or the variable stiffness elements themselves. Not only the unreasonance property, but also the damping property of the structure are compositely judged by a computer on the basis of information obtained from sensors with respect to disturbances such as earthquake and wind to control the connecting condition of the variable damping device, whereby both the unresonance property and the damping property are controlled to reduce the response amount of the structure. Otherwise, the variable damping device is controlled by the judgement of only the damping property.