Damping Optimization in Seismic Isolation Systems

To protect civil buildings, industrial facilities and bridges against earthquakes and explosions, various seismic isolation systems (SIS) are used. SISs always include dissipative elements that dissipate energy transmitted to the protected object (PO) during seismic effect, operation of which is based on the elastic-plastic deformation of special structures — elastic-plastic dampers (PD). The paper proposes a method for selecting the optimum design parameters of elastic-plastic dampers in SISs. The problem is solved upon specifying an ensemble of random seismic effects. A suite of artificial accelerograms obtained by statistical modeling is used as a stream of events supplied to the right side of motion equations. Dispersion of PO absolute accelerations was chosen as an optimization criterion. After linearization of the model, the dimensionless damping coefficient introduced into the dynamic model according to the Voigt–Bock hypothesis was taken as a variable parameter. Relationship between the selected optimization criterion and the theory of seismic risk of V.V. Bolotin has been established. It is shown that optimization of the damping coefficient reduces the seismic risk by 1.5–1.8 times. A method has been developed for transition from the optimum damping coefficient to design parameters of elastic-plastic dampers that implement this coefficient. Analytical dependences have been obtained enabling to set those parameters easily.