PASSIVE VIBRATION ISOLATION OF STRUCTURES (original) (raw)
Related papers
J. Eng. Technol. Res, 2011
Although a great deal of research has been carried out regarding seismic isolation, there is a lack of proper research on its behavior and implementing technique in low to medium seismic region. The basic intention of seismic protection systems is to decouple the building structure from the damaging components of the earthquake input motion, that is, to prevent the superstructure of the building from absorbing the earthquake energy. This paper reviews a number of articles on base isolation incorporation in building structure. Lead rubber bearing (LRB), high damping rubber bearing (HDRB), friction pendulum system (FPS) have been critically explored. This study also addressed the detail cram on isolation system, properties, characteristics of various device categories, recognition along with its effect on building structures. Meticulous schoolwork has also been accomplished about installation technique for various site stipulations. The entire superstructure is supported on discrete isolators whose dynamic characteristics are chosen to uncouple the ground motion. Displacement and yielding are concentrated at the level of the isolation devices, and the superstructure behaves very much like a rigid body. Rigorous reckoning illustrated the isolation system as very innovative and suitable in buildings to withstand the seismic lateral forces and also contributed to safety ensuring flexibility of structures.
Journal of Engineering and Technology Research, 2011
Although a great deal of research has been carried out regarding seismic isolation, there is a lack of proper research on its behavior and implementing technique in low to medium seismic region. The basic intention of seismic protection systems is to decouple the building structure from the damaging components of the earthquake input motion, that is, to prevent the superstructure of the building from absorbing the earthquake energy. This paper reviews a number of articles on base isolation incorporation in building structure. Lead rubber bearing (LRB), high damping rubber bearing (HDRB), friction pendulum system (FPS) have been critically explored. This study also addressed the detail cram on isolation system, properties, characteristics of various device categories, recognition along with its effect on building structures. Meticulous schoolwork has also been accomplished about installation technique for various site stipulations. The entire superstructure is supported on discrete isolators whose dynamic characteristics are chosen to uncouple the ground motion. Displacement and yielding are concentrated at the level of the isolation devices, and the superstructure behaves very much like a rigid body. Rigorous reckoning illustrated the isolation system as very innovative and suitable in buildings to withstand the seismic lateral forces and also contributed to safety ensuring flexibility of structures.
Multiaxial active isolation for seismic protection of buildings
Structural Control and Health Monitoring, 2013
Passive isolation has been widely accepted as an effective means for the protection of structures against seismic hazards. The isolation bearings, typically placed at the base of the structure, increase the flexibility of the structure and shift its fundamental frequency away from the dominant frequency of seismic excitations, resulting in significantly reduced interstory drifts and floor accelerations. During severe earthquakes, the performance of passive isolation systems is usually achieved at the expense of having large base displacements. Alternatively, active isolation combines isolation bearings with adaptive actuators to effectively mitigate the base displacements, while maintaining reasonable interstory drifts and floor accelerations. Despite successfully theoretical proof documented in previous studies, most experimental implementations only verified active isolation with unit-axial actuators under unidirectional excitations. Earthquakes are intrinsically multidimensional, resulting in out-of-plane responses such as torsional responses. Therefore, the focus of this paper is the development and experimental verification of active isolation strategies for multistory buildings subjected to bidirectional earthquake loadings. First, a model building is designed to be dynamically similar to a representative full-scale structure. The selected isolation bearings feature low friction and high vertical stiffness, providing stable behavior. In the context of the multidimensional response control, three custom-manufactured and appropriately scaled actuators are employed to mitigate both in-plane and out-of-plane responses. In addition, the structure is subjected to multi-directional earthquake ground motion. To obtain a high-fidelity model of the active isolation systems, the authors propose a hybrid identification approach, which combines the advantages of the lumped mass model and nonparametric methods. Control-structure interaction is also included in the identified model to further enhance the control authority. By employing the H 2 /LQG control algorithm, the controllers for the hydraulic actuators are shown to offer high performance and good robustness. Active isolation is found to possess the ability to reduce base displacements and produce comparable accelerations and interstory drifts to passive isolation. The proposed active isolation strategies are validated experimentally for a six-story building tested on the six-degree-of-freedom shake table in the Smart Structures Technology Laboratory at the University of Illinois at Urbana-Champaign.
A parametric study of linear and non-linear passively damped seismic isolation systems for buildings
Engineering Structures, 2004
The effects of near-field ground motions with large velocity pulses have motivated passive damping requirements for the protection of seismically isolated structures. Structures in which the first mode damping exceeds 20% or 30% typically do not exhibit classical modes, and simulation via a simple superposition of uncoupled second order equations is not possible. When the damping is produced by viscous or linear visco-elastic devices, we can, however, gain insight into the dynamic behavior of these structures using a convenient first-order formulation and frequency domain methods. When the damping effects are created by nonlinear mechanisms such as yielding or friction, the behavior of the structure is amplitude dependent and analyses are commonly carried out in the time domain. In this paper, frequency domain analysis and earthquake time history analysis are applied to study the influence of isolation damping on higher-mode effects and inter-story drift ratios. Because higher mode effects, plan irregularities, and bi-directional ground motions are all important attributes of the dynamic behavior of these structural systems, a simple comparison of isolation damping mechanisms can not be carried out via simple single or two degree of freedom realizations. In order to incorporate these important details in the study of the dynamic behavior of these structures, a set of 8-story prototype building models with L-shaped floor plans, different isolation periods, isolation damping characteristics, and levels of isolation stiffnesses are examined.
Study on Seismic Analysis of Buildings Using Combination of Different Isolation Systems Abstract
2015
The basic idea of base isolation system is to reduce the earthquake induced inertia forces by increasing the fundamental period of the structure. The aim of this study is the use of Lead rubber bearing (LRB) and friction pendulum system (FPS) as an isolation device and then to compare various parameters between fixed base condition and base isolated condition. With an aim of better including/understanding the effect of the emplacement of these devices on the response of the structures, the comparative studies were carried out in this article. The analysis is carried out by four comparative studies: the 1st and the 2nd between a fixed base structure and LRB and FPS base isolated ststems and the 3rd and 4th between a fixed base structure combination of isolation systems. The isolated structure by FPS system decreases displacements, accelerations and shear forces compared to the structure isolated by LRB. The isolated structure with Comb1 system decreases the displacements and shear fo...
SEISMIC ISOLATION AND ENERGY DISSIPATING SYSTEM FOR EARTHQUAKE RESISTANT DESIGN
International Journal of Engineering Applied Sciences and Technology, 2020 Vol. 4, Issue 11, ISSN No. 2455-2143, 2020
The concept of protecting a building from damaging effects of an earthquake by introducing seismic isolation and energy dissipating system. This concept was firstly emerged in the early 1970's. In China, the first energy dissipation structure was built at about same time. Over the past few decades, the ductility based conventional methods are being used for earthquake resistant design of structures. During a major earthquake, life safety can be achieved to the required level by these methods. In order to overcome this drawback in recent times, considerable attention has been given to the innovative, non-conventional method of earthquake resistant design & this innovative method found more reliable and effective means of earthquake hazard mitigation. In this paper an attempt has been made to give the overview of this non-conventional system which includes the concepts of seismic base isolation and energy dissipation (Damper) and basic working principle of passive, active, hybrid and semi-active control system. Seismic isolation and energy dissipating system present an effective way to common seismic design for improving the seismic performance of structures. This technique reduces the seismic forces by changing stiffness and/or damping in the structures, whereas conventional seismic design is required for an additional strength and ductility to resist seismic forces. The research and development work of passive, active, hybrid devices are ongoing intensively. This technique is not yet very common, but a research activity is going on in order to investigate the behavior of the isolated building. Civil engineer, owner, contractors have great responsibility concerning application of these system.
Seismic Isolating Systems. Classification, Properties and Utilization
bipcons.ce.tuiasi.ro
Flexible buildings can produce excessive vibration due to wind action, thus affecting the comfort of residents but also the structural system. To ensure the functional performance of the flexible structure have been adopted several solutions (flexible structures driven by wind and earthquake require dampers) while those driven only by the earthquake are rigid and require base isolation systems. An overview of measures to reduce structural response including a discussion of auxiliary damping devices, as well as recent examples of their use in countries such as USA, Japan, Turkey, Italy, is presented.
2020
The latest research activities in progress at the University of Chile on base isolation and passive energy dissipation are presented. These include analysis of seismic records obtained at seismic isolated structures and shaking table test results from scale model structures: a shear wall building with base isolation and a steel frame building with copper based alloy dissipative bracing. The scale models were subjected to different seismic inputs, including horizontal as well as vertical components. Analytical models are developed to reproduce experimental results.
Earthquake Vibration Control of Multi Storey Building Using Base Isolation System: A Review
International Journal for Research in Applied Science & Engineering Technology (IJRASET), 2022
Earthquake, any sudden shaking of the ground caused by the passage of seismic waves through Earth's rocks. Major earthquake in recent years have highlighted the big concern of modern seismic design concept for the resilience of building. The overall goals of this thesis aim to design structural vibration control using smart material and devices and to elucidate the factors determining their robustness, feasibility, and adaptability for earthquake-resistant and resilient building. SAP2000 is a tool used for creating and analysing structural models. It offers many features across a single, customizable user interface, allowing engineers working on transportation, industrial, public works, or other facilities to generate complex models and run comprehensive tests. Earthquakes shake the ground surface, can cause buildings to collapse, disrupt transport and services, and can cause fires. They can trigger landslides and tsunami. Earthquakes occur mainly as a result of plate tectonics, which involves blocks of the Earth moving about the Earth's surface.
Nonlinear damping based semi-active building isolation system
Journal of Sound and Vibration, 2018
Many buildings in Japan currently have a base-isolation system with a low stiffness that is designed to shift the natural frequency of the building below the frequencies of the ground motion due to earthquakes. However, the ground motion observed during the 2011 Tohoku earthquake contained strong long-period waves that lasted for a record length of three minutes. To provide a novel and better solution against the long-period waves while maintaining the performance of the standard isolation range, the exploitation of the characteristics of nonlinear damping is proposed in this paper. This is motivated by previous studies of the authors, which have demonstrated that nonlinear damping can achieve desired performance over both low and high frequency regions and the optimal nonlinear damping force can be realized by closed loop controlled semi-active dampers. Simulation results have shown strong vibration isolation performance on a building model with identified parameters and have indicated that nonlinear damping can achieve low acceleration transmissibilities round the structural natural frequency as well as the higher ground motion frequencies that have been frequently observed during most earthquakes in Japan. In addition, physical building model based laboratory experiments are also conducted, The results demonstrate the advantages of the proposed nonlinear damping technologies over both traditional linear damping and more advanced Linear-Quadratic Gaussian (LQG) feedback control which have been used in practice to address building isolation system design and implementation problems. In comparison with the tuned-mass damper and other active control methods, the proposed solution offers a more pragmatic, low-cost, robust and effective alternative that can be readily installed into the base-isolation system of most buildings.