Viscous fluid dissipation system model acting on the active principle

Abstract

There are solutions in terms of seismic isolation and energy dissipation that are successfully applied all over the world to building structures but also to high-way and rail infrastructure elements represented by bridges and viaducts. These structures must remain functional even after they have been requested by a considerable magnitude earthquake. This is why research activities aiming the development and modernization of these mechanical systems, which play a decisive role in ensuring the optimal stability of these structures, are justified. Fluid dissipation systems were originally developed as passive protection systems but over time they have been constructively improved with intelligent control systems that have the potential to considerably increase the efficiency of these systems by making use direct control over the amount of energy which can be dissipated through these protection systems. Such a dissipative viscous fluid system is described in this paper as a more evolved constructive system than the passive principle model. Active control over the operation of this device is materialized by altering the working fluid flow rates through the constructional elements of the dissipation device assembly. This flow rate adjustment is made by means of a flow controller present within the control unit. The mathematical model characterizing the functioning of an active viscous fluid dissipation system is presented, as well as a numerical analysis describing the function of such a dissipative system depending on the additional mass of the isolated structure to which the protective device is attached. The numerical analysis is based on a set of specific values presented in the paper. These dissipation systems are primarily used in bridge or viaduct structures, being responsible for limiting the relative displacements between the structural elements where they are mounted. This method provides greater security through the rigid connection achieved between the structural frames acting as anchorages. Entry into action is made in the occurrence of a seismic event when the piston displacement is recorded and by changing the momentarily flow rate values of the circulating fluid the amount of energy dissipated is adjusted by means of the viscous fluid device. There are presented the advantages and disadvantages related to the use of such seismic energy dissipative systems attached to the construction structures.