VISCOELASTIC DAMPERS PDF DOWNLOAD
In recent years, viscoelastic dampers (VEDs) have been widely used in many mid- and high-rise buildings. This study introduces a viscoelastic Abstract · Introduction · Experimental setup · Results and discussion. Chapter 6 – Viscous-Viscoelastic Dampers. 1. Introduction. • Damped Outrigger Concept to mitigate wind vibrations in tall buildings -The St. Francis. The seismic response control of multistory frame structures using optimally placed viscoelastic dampers (VEDs) within consideration of.
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Viscoelastic dampers of VE rubber dampers is a rate dependent phenomenon [ 3 — 8 ]. In recent years, numerical tools such as finite element viscoelastic dampers have been utilized to optimize the structure of VE rubber damper devices [ 910 ]. VEDs have made a great contribution in vibration control of aerospace structures [ 1112 ] and civil engineering structures since [ viscoelastic dampers — 17 ].
The typical configuration of VEDs is such that the VEM is bonded between steel plates to dissipate oscillation energy. This manner of damping reduces floor acceleration, interstory displacement and interstory shear [ 18 — 22 ].
Shock and Vibration
Advantage of VEDs over VFDs is that application of VEMs results in small increment of structural stiffness and this is due to their inherent storage stiffness, yet to lower degree as metallic yielding devices. In addition, VEDs are able to dissipate energy against all levels of ground motion.
The RRBD shares this viscoelastic dampers. Generally speaking, VEDs are known as some viscoelastic dampers most efficient vibration control devices in strengthening existing and new buildings against wind and earthquake [ 23 ].
Recent years have witnessed many practical projects and studies regarding VEDs. These studies have involved development of various configurations [ viscoelastic dampers24 — 28 ]. Materials of VEDs are readily available and that makes them more common damper devices.
Modeling of a viscoelastic damper and its application in structural control
However, it is not easy to reach to a balance between stiffness and damping. The RRBD overcomes this issue through sufficient number of parameters to control viscoelastic dampers balance.
By carrying out a review of viscoelastic dampers systems prior to presenting the proposed system has put the idea into perspective.
Braced frames viscoelastic dampers designed to resist both gravity and lateral loads in beam bending and column compression, and axial compression and tension, respectively.
Numerous braced frame types exist including K-bracing, V-bracing, X-bracing, CB and single diagonal [ 29 ]. In order to ensure correct bracing type and position, both primary and secondary criterion lateral drift and architectural objectives, respectively need to be considered. A comparison study of four bracing types, X-bracing, eccentric bracing, CB and single diagonal bracing, by Alshamrani et viscoelastic dampers.
Additionally, CB displayed greater flexibility for service passages and other openings, like doors and windows, whilst Viscoelastic dampers was more obstructive. This led the authors to conclude that CB was viscoelastic dampers efficient, had lower costs and improved architectural aspects compared to the other bracing options.
The nonlinear cyclic response of the brace dictates the dissipation of seismic energy in a Chevron braced frame CBF.
Cyclic axial force deformation behavior of a brace is asymmetrical in tension and compression and buckling effects often result in significant strength and stiffness deterioration [ 31 ]. Therefore, when a CBF is subjected to large ground motions, there is a loss of lateral stiffness and a weakening of the frame due to the inelastic buckling of the braces [ 32 ].
The early buckling of the braces at viscoelastic dampers floor levels [ 33 ] make it difficult to obtain well distributed viscoelastic dampers demands throughout the height of the CBF causing soft-story formations, substantial damage to the frame members and dynamic instability [ 34 ].
A viscoelastic dampers number of research studies have been carried out in recent years that have considered new structural configurations [ 3235 ] and hysteretic, friction and VFD passive energy dissipation devices [ 36 — 38 ] and their ability to improve the performance of CBFs. There is a concurrent determination of structural members, such as beams, braces and columns, during the design of bracing system dampers.
This allows the frame to be designed with prior knowledge of the high axial forces generated by the braces. Conversely, a viscoelastic dampers seismic protection design should consider how the brace attachment viscoelastic dampers the initial frames can be affected.