Theoretical and numerical study of the thermo-mechanical coupling effect on the fluid viscous damper

Abstract

The fluid viscous damper (FVD) is a typical passive energy dissipation device applied to civil engineering structures for vibration control. However, the heat generated during its operation will alter the properties of the fluid, thereby affecting the damping force. This study explores the thermo-mechanical coupling effect on the performance of the FVD. A theoretical model is developed based on fluid dynamics and thermodynamics to reflect the interaction between the real-time damping force and temperature of the FVD. Computational fluid dynamics (CFD) simulations are performed to investigate the impact of the thermo-mechanical coupling effect on the hysteresis performance of the damper and validate the proposed calculation method. The dynamic behavior and vibration mitigation effectiveness of the FVD considering the thermo-mechanical coupling effect are examined based on time history analysis on a single-degree-of-freedom and a multi-degree-of-freedom system. The results indicate that the increased temperature will lead to a reduction in the damping force, while the degraded force will in turn slow the temperature rise. Long-duration and high-intensity excitations can significantly amplify the impact of the thermo-mechanical coupling effect, thus it is essential to be considered in designing dampers for loads in the service stage and major earthquakes. The thermo-mechanical coupling effect on the supplemental damping ratio of the damper is greater than that on structural response control effectiveness, thereby it cannot be neglected when the damping ratio is used as the design criterion for FVDs.