Study of lead rubber bearings operation with varying. Testing of high damping rubber bearings and lead rubber bearings for nuclear power plants maria gabriella castellano1, alberto dusi2 and alessandro poggianti3 abstract. Buildings free fulltext potential design of seismic. Dynamic properties of lead rubber bearings and its seismic.
Consider the reaction of a 16storey building on the seismic impact. The isosism lrb isolators consist of alternate layers of rubber and vulcanised reinforcement steel plates of limited thickness and a central lead core. The energy dissipation provided by the lead core, through its yielding, allows to achieve an equivalent viscous damping coefficient up to about 30%, i. A parametric study is conducted to investigate the effect of lead rubber bearing lrb isolator and ground motion characteristics on the response of seismic isolated bridges.
Maurer lead rubber bearings mlrb are devices for seismic isolation. Rubber bearing type linksupport element is used to model nonlinear behavior of lead rubber bearing in this study. Lrb is a novel apparatus based on the combination of laminated layers rubber bearing using lead plugs constantinou, et al. Could lead rubber base isolators be the answer to our earthquake fears. Heavy damping mechanism incorporated in vibration control technologies and, particularly, in base isolation devices, is often considered a valuable source of suppressing vibrations thus enhancing a buildings seismic performance. The higher energy dissipation capability of lead rubber bearing is due to the plastic deformation of lead core which deforms even under small shear stress which makes it suitable in strong earthquake regions. A leadrubber bearing is formed of a lead plug force. On top and bottom, the bearing is fitted with steel plates which are used to attach the bearing to the building and. Lead rubber bearings lrb are rubber bearings made up of alternate layers of steel laminates and hot vulcanized rubber with a cilindrical central lead core. To design the lead plug rubber bearing by using the data from etabs to design lrb 3. Earthquakes and the benefits of lead rubber bearing base isolation.
The second type of elastomeric bearings is leadrubber bearings lrb. The hysteretic behaviour of an lrb can also be modelled as linear, by means of the effective stiffness. The lead core rubber bearing is formed by processing a plurality of rubber pad layers in stacking mode, wherein a hole is formed in the middle of the rubber bearing, and a lead rod is inserted in the hole. Design of base isolation system for buildings by taichieh wu bachelor of science in civil engineering chungyuan christian university, chungli, taiwan submitted to the department of civil and environmental. Research paper excel spreadsheet for design of lead. Pdf effect of lead rubber bearing characteristics on the. However, in this type of bearing, the lead has a tendency to work its way out from between the plates.
Instead of using traditional bearings like ptfepot bearing lrb is found to be effective in high seismic region. Typical diagram of lead rubber bearing can be shown in figure 2. This bearing consists of alternate horizontal layers of steel and. Instead of using traditional bearings like ptfepot bearing lrb is found to be effective in high seismic region and it is used in many developed countries. The bearing plan shape can be round, square or rectangular, whereas the. Detailed design procedure of isolator lead rubber bearing slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Pravat kumar parhi published on 20180508 download full article with reference data and citations. Lead rubber bearings lrb isolators are elastomeric isolators with a cylindricalshaped core of lead. Lead plug rubber bearings were invented in new zealand in 1975. Lead rubber bearing or lrb is a type of base isolation employing a heavy damping. The natural rubber bearings show a linear behavior in shear up to shear strains above 100%, and have damping in the range of 23% of critical.
Many rubber based baseisolation techniques such as laminated rubber bearings, lead rubber bearings etc. Performance of lead rubber bearing as a base isolator. Lrb sangat elastis secara lateral tetapi sangat kaku secara vertikal. Due to the low damping nature of the natural rubber, rubber bearings are generally used with one or more lead cores, which are called lead rubber bearings lrbs. They consist of a steel reinforced elastomer bearing chloroprene caoutchouc or natural caoutchouc with additional lead core. The purpose was to investigate the most favorable parameters of the lrb for. The bearing, which consists of layers of rubber and steel with a lead core, was invented by dr robinson in 1974. Lead core rubber bearings lrb lead core rubber bearings lrb consists of a laminated rubber and steel bearing with steel flange plates for mounting to the structure. In the present study, the cyclic loading of two different isolating systems, namely, the high damping rubber bearing hdrb and lead rubber bearing lrb have been modeled and analyzed in abaqus and the outcomes were compared with the experimental results attained by other researchers. According to the lead core rubber bearing, the lead rod is inserted in the middle of the rubber bearing, and therefore the lead core rubber. Lead rubber bearing lead rubber bearings were invented in new zealand in 1975. Bearing is one of the important components of bridges. Vertical stiffness of elastomeric and leadrubber seismic.
The layers of steel provide vertical stiffness and the layers of rubber supply the device with high lateral flexibility. To study the effect of using lead rubber bearing on the. Dynamic behavior of rc framed irregular building using. A study on the seismic isolation systems of bridges with.
Base isolation lead rubber bearing friction pendulum mining rubber. The plasticization of lead permits to obtain an equivalent viscous damping coefficient up to approximately 30%. They allow the isolation of the structure by a proper selection of the horizontal stiffness and they can dissipate energy up to 30% damping due, to the high. The characteristic strength, which is among the important properties of lrbs, deteriorates as the number. The mechanism of lead plug rubber bearings is very similar to that of lowdamping natural rubber bearings. Products seismic isolator for buildings bridgestone. The rubber compound can be of natural rubber or chloroprene rubber, while any standard din, en, setra, asshto, bs, etc.
Among various seismic isolation systems, leadrubber bearing lrb which has innovative mechanism can lead to increased effective stiffness and is accommodating force in reinforced concrete rc structures. According to the calculation, 20 supports were set under the building. Fhwa bridge inspection manual section 9 bridge bearings. The typical hysteresis loop of a lead rubber bearing can be modelled as bilinear. The device is a regular rubber bearing for service condition and it is a seismic isolator for the seismic condition. The elastomer bearings, also referred to as deformation bearings, respond to displacements with elastic recentering forces. This video gives the information about lead rubber bearings.
The behavior adopting such technologies can be dynamically observed in simulated environments and thus serves as a valuable metric for their feasibility. The constitutive bond of lrb isolators is bilinear. Leadrubber bearings are another type of laminated elastomeric isolators. Tech dissertation conducted at ramaiah university of. This paper presents the design methodology of lead rubber bearing used for seismic isolation of bridges. While the elastomeric bearing mainly takes over the support and recentering function, the lead core serves for efficient energy dissipation in.
In a building with seismic isolation lead rubber bearings lrbsn 1100220200 5, p. It was invented by william robinson, a new zealander. By placing a thin lead sheet between the steel plates, it is possible to keep the plates from freezing together when they corrode. Lead rubber bearing lrb lead rubber bearing lrb terdiri dari bantalan karet dan baja yang dilaminasi dengan pelat baja untuk pemasangan ke struktur. Numerical modeling of elastomeric seismic isolators for. Maurer lead rubber bearings mlrb are based on the design principles of the en37 structural bearings and the pren15129 anti seismic devices. The iterative progressions were adopted to assess and adjust the varied types and layouts satisfying the design requirement. Here, a perfectly circular hole is made in the middle of a laminated bearing and filled with a lead core, which provides damping. Design of base isolation system for buildings design of base. There are three main pieces of equipment, layers of steel plates, rubber layers and lead core, respectively. Research paper excel spreadsheet for design of lead rubber. Modeling of lead rubber bearings via 3d basis, sap2000. Effectiveness of lead rubber base isolators, for seismic resistance of.
A lead rubber bearing is made from layers of rubber sandwiched together with layers of steel. Network for earthquake engineering simulation, researchers are studying the performance of base isolation systems. The seismic hazard of vulnerable regions warrants the investigation of new technologies, such as base level isolation by lead rubber bearing lrb devices, that can help to mitigate structural damage on seismic prone buildings. The parameters d 1, f 1, d 2, and f 2 that define the bilinear curve are given in the following tables per each standard lrb. This type of isolator provides more damping than highdamping rubber, typically up to 30%. For leadcore can dissipate seismic energy and increase stiffness under load simultaneously, and most of the requirements of the seismic. Rubber bearing that has a lead plug embedded at the centre of laminated natural rubber. Lead sheets are used to reduce corrosion between the plates, thereby providing more freedom of movement. Base isolation of residential building using lead rubber bearing technique written by dhiraj narayan sahoo, dr. Leadrubber bearings lrbs have one or more lead plugs that are inserted into holes in a lowdamping natural rubber bearing to increase the damping capacity. The rubber compounds normally used in the production of lrb are characterised by an effective dynamic shear modulus g. Effectiveness of lead rubber base isolators, for seismic. Lead rubber bearing consists of a laminated elastomeric rubber bearing equipped with lead cylinder at the centre of the bearing. The paper describes a wide testing campaign carried out on full scale prototypes of elastomeric isolators both high damping rubber bearings hdrb and lead rubber.
Ninety percent of our isolators have an energy dissipating lead core. A ucl civil engineering student workshop about earthquake engineering. Base isolation of residential building using lead rubber. The function of the rubber steel laminated portion of the bearing is to carry the weight of the structure. Maurer lead rubber bearings mlrb are seismic devices designed as a combination of a conventional elastomeric bearing with inserted lead cylinders. The study presented in this paper aims to provide some clarification on the tensile response of lead rubber bearings by. This base isolation system provides the combined features of vertical load support, horizontal flexibility, restoring force, and damping in a single unit. A wide variety of lead rubber bearing options are available to you, such as single row.
For nonlinear rubber bearing, bilinear forcedeformation properties including. Lead rubber bearings as base isolating devices for the. These are the frequentlyused types of base isolation bearings. Lead rubber bearing lrb is a new type of earthquakeresistance rubber bearings, formed by inserting leadcore into ordinary laminated rubber bearing, vertical supporting, horizontal displacement and hysteretic damping are hung in single unit together. Bearing rubber bearing rigid elastic natural leadplug highdamping. Required amount of damping can be produced by selecting the appropriate size of lead plug and also bearing provides elastic restoring force. If you continue browsing the site, you agree to the use of cookies on this website. The lead plug was forced in to the steel plates in the bearing deforms the shear.
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