Design aspects regarding a hydraulic dissipation system assembly model and virtual operation results

Abstract

Ensuring an optimal stability degree for building structures represents the basic engineers concern when working on developing projects for new structures or rehabilitation of old ones. The most important dynamic actions with destructive effects threatening a building structure are the seismic actions which place important stress under dynamic regime inside building structural elements but also vibration actions resulting from road or rail traffic acting on the bridge structure types. Special isolation methods have been developed, over time, in order to counteract the destructive effects of the mentioned dynamic actions by using mechanical devices directly mounted on the structural frames of a building, with the declared role of protecting the structure during the occurrence of these unexpected events. A structure having in composition such protective systems is considered an isolated structure against dynamic actions and devices used are classified as insulation systems or energy dissipative systems because they are able to consume an amount from the disturbing action input energy transforming it into another form energy, namely heat. A mechanical device model with energy dissipation properties is described in this paper that can be used for mounting at buildings and bridges in order to achieve energy consumption when a dynamic mode action acts on the isolated structure. This dissipative device assembly is achieved as a hydraulic cylinder with piston operating on the basis of a fluid with special viscosity properties. The piston, being solidary with the rod, has a number of orifices made necessary for the working fluid circulation so that when a request occurs it can perform a relative translational motion relative to the cylinder. The mounting solutions for the hydraulic dissipation system at the insulated structure are made by means of metal flanges positioned on the structural elements that allow a relative displacement during earthquakes and which must be limited by means of the energy dissipation action. An assembly model for the hydraulic dissipative device is built for which fluid flow analysis is performed inside the cylinder and through the piston orifices for different velocity values during rod translational motion. It is also analyzed the dissipation device operation for different orifice diameter values which ensure the working fluid circulation, as well as the different types of hydraulic fluid used. The results are presented for each case analyzed in part, where the role of dissipative device of the analyzed system is being emphasized.