Analysis and design of reinforced concrete structures with spring. Our base isolation products are flexible earthquakeproof systems. Base isolation, as a strategy to protect structure from earthquake, revolves around. Base isolation has become one of the reliable tools for earthquake resistant design of the structure. Hybrid base isolation systems with semiactive devices 1, named smart base isolation systems, have been proven to be effective against a wide range of ground excitations. Naeim and kelly 1999 is a technique that mitigates the effects of an earthquake by essentially isolating the structure and its contents from potentially dangerous ground motion, especially in the frequency range. Extraction involves dissolving a compound or compounds either 1 from a solid into a solvent or 2 from a solution into another solvent. In one method, laminated rubber bearings are installed onto the tops of piles that have been cut to provide a space while an upper structure is being supported. Many are being already constructed and many are under construction.
Base isolation is a technique developed to prevent or minimise damage to buildings during an earthquake. Base shear is used for the design of the baseisolation system and the fbps. Baseisolation techniques for the seismic protection of rc framed. According to the innovative technology developed by the. The technique of base isolation allows to go around the aforementioned problem. Displacements of buildings in base isolated buildings and fixed base buildings. The experimental tool developed here was implemented in an undergraduate course introduction to earthquake engineering, and the results of student analyses are presented. Engineers and architects have been carrying out studies for over one hundred years to find applicable methods to reduce the response given to the ground motions by the structures. Second includes working on the correct modeling of structures with and without base isolation. Buildings with base isolation techniques slideshare. That is why the method of base isolation and method of controlling dynamic response are used in designing the objects that remain in service after the earthquake.
Base isolation this is the most widely used method against earthquake damage. The flexible pads are called baseisolators and structures using these devices are called baseisolated buildings. Base isolation is required if any circumstances arise of the following. Mar 17, 2017 base isolation is a stateoftheart method in which the structure superstructure is separated from the base foundation or substructure by introducing a suspension system between the base and the main structure. Pdf fundamentals of seismic base isolation researchgate. Seismic coefficient method helps to determine base shear considering only the fundamental mode of the structure. Base isolation 3 3 cascaded ground motion and structural systems and r. Earthquake resistant construction using base isolation govinfo. Base isolation minimizes the need for strengthening measures of adding shear walls, frames, and bracing by reducing the earthquake forces imparted to the building. Effect of base isolation on the response of reinforced.
Base isolator is a more flexible device compared to the flexibility of the structure. The flexible pads are called base isolators and structures using these devices are called baseisolated buildings. Seismic or base isolation is a design technique that reduces the force demand on structures by isolating them from the damaging effect of the ground motion. Apr 08, 2019 base isolation mitigates motion of the structure due to seismic activity. Chapter 10 the asce 710 design provisions for seismically. Development of a friction pendulum bearing base isolation. The method of base isolation was developed in an attempt to mitigate the effects of earthquakes on buildings during earthquake attacks and has been practically proven to be one of the very effective methods in the past several decades. Seismic retrofitting by base isolation and analysing through. Seismic retrofitting by base isolation and analysing. Currently, many researchers are attempting to develop lowcost base isolation intended for lowrise buildings by replacing steel reinforcement with an alternative material. Although remaining general, the design requirements rely on mandatory testing of isolation system. It is one of most powerful tools of earthquake engineering pertaining to the passive structural vibration control technologies.
It is the method of providing a support to the foundation for the buildings in seismic zones as it enables the reduction in earthquake induced forces by increasing the period of vibration of the structure. The base isolation system is wellknown as a sophisticated device for reducing earthquake energy that a building structure is subjected to under earthquake impact. It is easiest to see the principle at work by referring directly to the most widely used of these advanced techniques, known as base isolation. The method of base isolation was developed in an attempt to mitigate the effects of. In particular, highdampinglaminatedrubber bearings are considered, in case acting in parallel with supplemental viscous dampers, or acting either in parallel or. As a result, not only are the seismic forces on the structural elements reduced but. Base isolation systems journal of rehabilitation in civil engineering.
The idea is to supply this building with seismic isolation in the foundation by gradually cutting the isolators into the walls at the level of foundation upper edge by means of a twostage system of rc beams. Pdf base isolation bi system for buildings is introduced to decouple the building structure from potentially damaging induced by earthquake motion. The basic concept of seismic isolation is to reduce the response to earthquake motion by, earthquake response. Chapter 8 base isolation for earthquakeresistant design. Seismic isolation is commonly referred to as base isolation because the most common location of the isolation system is at or near the base of the structure. What is base isolation system in building construction. Two activitiesbase isolation for earthquake resistance. The effectiveness of the proposed smart base isolation. A base isolated structure is supported by a series of bearing pads which are placed between the building and the buildings foundation. The top floor acceleration is a measure of the human comfort in the structure during an earthquake. Base isolation, time history analysis, response spectrum analysis, matrix stiffness calibration method. The design of a full isolation system requires special analyses that explicitly include vertical ground shaking and the potential for rocking response. Building design for resisting earthquake by base isolation method.
In the other, laminated rubber bearings are installed between an existing base and a. The isolation system configured to produce a restoring force such that the lateral force at the total design displacement is at least 0. Base isolation, as a strategy to protect structure from earthquake, revolves around a few basic elements of understanding. A familiar example of the first case is making a cup of tea or coffee the soluble flavor and odor chemicals and caffeine are extracted from the solid tea leaves or. Displacement occurs at cg of the structures for fixed base structures, which will be approx. The performances of the intended ductile structures during major earthquake, however, have been proved to be unsatisfactory. Therefore, special techniques are required to design building such. Base isolation reduces earthquake intensity and losses.
Pdf buildings with base isolation techniques report. Base isolation has become popular in last couple of decades in its implementations in buildings and bridges. A fixed base building built directly on the ground will move with an earthquakes motion and can sustain extensive damage as a result. In this method of aseismic design, the entire structure is founded on several reinforced elastomer bearings which isolate the structure from severe horizontal seismic ground motions. Chapter commentary seismically isolated structure design. After extensive and wideranging investigations and evaluations, the base isolation method was selected as the appropriate rehabilitation solution. Schematic representation of design methods with ensuring ductility and base isolation using base isolation the seismic response of the structure is reduced by preventing the. Seismic base isolation is an important technique that is used for mitigating seismic vulnerability by decreasing the seismic demand instead of increasing the seismic capacity. Combined with the concrete facts of base isolation technique in china, it is suggested that two step design method may be used to design base isolation device. A familiar example of the first case is making a cup of tea or coffee the soluble flavor and odor chemicals and.
Tell students that one way to protect a building from resonating with an earthquake is to isolate its foundation, or base, from the ground with devices much like wheels. Base isolation has become a traditional concept for structural design of buildings and bridges in high risk areas. This passive control technique basically decouples the structure from the ground motion by introducing a flexible or sliding type interface. It is the method of providing a support to the foundation for the buildings in seismic zones as it enables the reduction in earthquake induced forces by increasing the period of. Thks base isolation systems are capable of achieving base isolation even with.
The reference value, definition and measurement method of the accuracy after. The concept of base isolation system had been suggested in last few decades and the available technologies and the knowledge of base isolation system are getting mature and. T100 equation 6 the transmissibility as a function of frequency ratio is shown in figure 3. Base isolated structure exhibit less lateral deflection, as the lateral displacement at the base never equals to zero, and less moment values than the fixed base structure. Base isolation consists of the installation of the support mechanisms, which decouple the structure. Pdf on jan 1, 2002, yenpo wang published fundamentals of seismic base. Objectives of the work to the earthquake resistance of buildings and avoid the possible damage of building by using base isolation technique. Base isolation and seismic dampers science learning hub. Base isolation can be further divided into two methods. Suitability of base isolation earthquake protection of structures using base isolation technique is generally suitable if the following. Damper, base isolation by time history method jadhav nachiket s. In context of seismic design of structures, base isolation. Types of isolators most of the base isolation system includes either the.
The smart base isolation systems can potentially reduce the associated displacement at base and sli ghtly increase the structural acceleration. Mar 04, 20 base isolation, response spectrum analysis, rc building, elastic a nalysis. Earthquake resistant construction using base isolation nist. Currently, many researchers are attempting to develop lowcost base.
Base isolation method for existing buildings with bearing walls that envisions placing of seismic isolators at the level of the foundation or the basement solves the problem as shown on figure 2. Base isolation is one of the most promising alternatives among the structure control methods. Isolation of bridges base isolation bearings serves the dual purpose of providing for thermal movement as well as protecting the bridge from dynamic loads the bridge is seismically retrofitted by using the elastomeric identical bearings at pier and abutment locations abutment isolation system or bearings pier deck rock line. Scope of problem to fulfill the aim following scope of work was outlined.
Base isolation concept was coined by engineers and scientists as early as in the year 1923 and thereafter different methods of isolating the buildings and structures from earthquake forces have been developed world over. The advantages and disadvantages of these methods are discussed. In the case of base isolation technique, which is the most popular responsecontrol structure technique, a device having some damping properties and sufficient. This study tries of clarify the advantage of the base isolation technique with. Modeling of seismic isolation bearings in computer software. Research and development of seismic base isolation technique for.
Base isolation is a powerful technique that has been developed and being extensively adopted especially in severe seismic zones to protect structures against. Base isolation techniques applications, advantages. Base isolation seminar report, ppt, pdf for civil engineering. Seismic isolation consist essentially the installation of mechanisms which decouples the. In addition, the latest advances and new methods developed in this field have been introduced. Base isolation technique the base isolation technique is a seismic design approach in which, due to the insertion of a flexible layer between the foundation and the superstructure, the fundamental frequency of the system decreases to a value lower than the predominant energy containing frequencies of earthquake ground motion. D y patil school of engineering and technology, charholi, pune412105, india. Installation of a base isolation system made of friction. Seismic isolation is a method to reduce the destructive effects of earthquakes on a structure in which the structure is separated from its foundation by devices called seismic. Seismic base isolation, also known as base isolation, or base isolation system, is one of the most popular means of protecting a structure against earthquake forces. Seismic isolation methods, passive control, friction pendulum isolators.
While these passive methods have been used in applications to reduce the deformation demand on the isolation. Study by modeling the prototypes structural of foundations base isolated foundations, and original foundations. The effective reduction of interstory drift in the floor of base isolation system can ensure the lowest damage to facilities and also human safety. Building design for resisting earthquake by base isolation. The base isolation technique background on base isolation for earthquake resistance adaptations and extensions from the boss model activity 1. The concept of base isolation system had been suggested in last few decades and the available technologies and the knowledge of base isolation. The selected values of effective isolator stiffness keff in x and y directions are chosen by trial and error method to achieve a final tolerance of 0. The study analysis performed to check for the adequacy of the base isolation against building lateral drift and interstory drift as per allowance in national building code of canada 2010. To compare the condition of the shake of the structure. Base isolation base isolation is the most commonly adopted method for earthquake resistant building. For minimum transmissibility maximum isolation, the excitation frequency should be as high above the natural frequency as possible. Rather than addressing a specific method of base isolation, the provisions provides general design requirements applicable to a wide range of possible seismic isolation systems. Base isolation is widely used in the earthquakeresistant design. Dec 28, 2015 applications base isolation provides an alternative to the conventional, fixed base design of structures.
The reference value, definition and measurement method of the accuracy after the installation after installing the system, mount anchor plate and other devices so that the following definitions and accuracy. Isolation is a method that reduces the seismic response of a. It has been used in new zealand, as well as in india, japan, italy and the usa. Parametric study of different types of base isolation techniques. Base isolation of buildings thks base isolation systems are capable of achieving base isolation even with lightweight buildings and. The main content of base isolation structure design consists of two parts. Base isolation is the ideal method to cater this, by reducing the transfer of motion, the displacement of building is controlled. Study on earthquake resistant building base isolation. Base isolation and damping systems for earthquake resistance. Researchers have done various important researches on the base isolation system, which has been fully accepted in the engineering field.
The rehabilitation necessity was imperative, since the church was severely damaged by numerous strong seismic actions during the last 400 years. In recent decades, base isolation has been seriously considered. A spongetype mr damper is installed between the base and the ground to provide controllable damping for the system. It is a collection of structural elements which should substantially decouple a superstructure from its substructure that is in turn resting on the shaking ground, thus protecting a building or nonbuilding structures integrity. Base isolation method for existing buildings with bearing walls. Base isolation had the effect of reducing the earthquake force demands on the superstructure to 30% of the demands for a fixed base structure. Basic elements of a base isolation isolation system the various isolators, which facilitate the time period shift of the structure to a period range of 2 to 3 sec, form the isolation system structural system this system comprises of the structural components of the superstructure as well as the foundation.
465 1459 838 1287 1482 646 1405 65 271 616 1245 316 1169 1202 677 1049 1382 605 320 244 1389 257 675 84 79 980 286 300 1114 748 106 834 944 932 1062 781 734