Adjacent structures coupled by viscous damper subjected to random excitations

Abstract

In this paper, the dynamic response of adjacent structures, modeled as single-degree-of-freedom (SDOF) structures connected by viscous damper, under random excitations is investigated. The ground motion is modeled by a non-stationary random process. To study the influence of non-stationary characteristics of ground motion, the non-stationary response of the coupled structure is compared with the corresponding stationary response. An optimum value of the damping coefficient of viscous damper for which mean square relative displacement and mean square absolute acceleration of the coupled structures attain a minimum value is observed. The influence of system parameters such as frequency ratio, mass ratio and intensity of an earthquake on the optimum value of damper damping is investigated. It has been observed that the frequency ratio and intensity of an earthquake have significant effect on the performance of the viscous damper, whereas, the effect of mass ratio is marginal. An explicit expression for the optimum value of damper damping and corresponding response of the connected structures are proposed. These expressions are derived for the coupled structures subjected to the white noise excitation. The expressions may be used for preliminary optimal design of the viscous damper for connected structures.