Detailed design procedure of isolator lead rubber bearing slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. In a building with seismic isolation lead rubber bearings lrbsn 1100220200 5, p. This paper presents the design methodology of lead rubber bearing used for seismic isolation of bridges. 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.
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. They consist of a steel reinforced elastomer bearing chloroprene caoutchouc or natural caoutchouc with additional lead core. Numerical modeling of elastomeric seismic isolators for. Modeling of lead rubber bearings via 3d basis, sap2000. The iterative progressions were adopted to assess and adjust the varied types and layouts satisfying the design requirement. 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. 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. Rubber bearing type linksupport element is used to model nonlinear behavior of lead rubber bearing in this study. Methodology the software used for analysis of a structure is etabs v 9. Here, a perfectly circular hole is made in the middle of a laminated bearing and filled with a lead core, which provides damping. The second type of elastomeric bearings is leadrubber bearings lrb.
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. Lead rubber bearing lead rubber bearings were invented in new zealand in 1975. Research paper excel spreadsheet for design of lead rubber. 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. 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. Lead plug rubber bearings were invented in new zealand in 1975. Dynamic properties of lead rubber bearings and its seismic.
The elastomer bearings, also referred to as deformation bearings, respond to displacements with elastic recentering forces. 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. Ninety percent of our isolators have an energy dissipating lead core. A study on the seismic isolation systems of bridges with. This video gives the information about lead rubber bearings. While the elastomeric bearing mainly takes over the support and recentering function, the lead core serves for efficient energy dissipation in. Base isolation of residential building using lead rubber bearing technique written by dhiraj narayan sahoo, dr. To study the effect of using lead rubber bearing on the. Effectiveness of lead rubber base isolators, for seismic. Lead rubber bearings lrb isolators are elastomeric isolators with a cylindricalshaped core of lead. Instead of using traditional bearings like ptfepot bearing lrb is found to be effective in high seismic region. 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.
For leadcore can dissipate seismic energy and increase stiffness under load simultaneously, and most of the requirements of the seismic. A lead rubber bearing is made from layers of rubber sandwiched together with layers of steel. This type of isolator provides more damping than highdamping rubber, typically up to 30%. The characteristic strength, which is among the important properties of lrbs, deteriorates as the number. The rubber compound can be of natural rubber or chloroprene rubber, while any standard din, en, setra, asshto, bs, etc. Pdf effect of lead rubber bearing characteristics on the. Bearing is one of the important components of bridges. Performance of lead rubber bearing as a base isolator. The function of the rubber steel laminated portion of the bearing is to carry the weight of the structure.
Lrb sangat elastis secara lateral tetapi sangat kaku secara vertikal. Research paper excel spreadsheet for design of lead. The device is a regular rubber bearing for service condition and it is a seismic isolator for the seismic condition. The typical hysteresis loop of a lead rubber bearing can be modelled as bilinear. Rubber bearing that has a lead plug embedded at the centre of laminated natural rubber. Maurer lead rubber bearings mlrb are based on the design principles of the en37 structural bearings and the pren15129 anti seismic devices. Design of base isolation system for buildings design of base. According to the calculation, 20 supports were set under the building. Network for earthquake engineering simulation, researchers are studying the performance of base isolation systems. On top and bottom, the bearing is fitted with steel plates which are used to attach the bearing to the building and. 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. The isosism lrb isolators consist of alternate layers of rubber and vulcanised reinforcement steel plates of limited thickness and a central lead core.
Buildings free fulltext potential design of seismic. The bearing plan shape can be round, square or rectangular, whereas the. A wide variety of lead rubber bearing options are available to you, such as single row. 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.
The energy dissipation provided by the lead core, through its yielding, allows to achieve an equivalent viscous damping coefficient up to about 30%, i. The behavior adopting such technologies can be dynamically observed in simulated environments and thus serves as a valuable metric for their feasibility. Maurer lead rubber bearings mlrb are seismic devices designed as a combination of a conventional elastomeric bearing with inserted lead cylinders. Tech dissertation conducted at ramaiah university of. The bearing, which consists of layers of rubber and steel with a lead core, was invented by dr robinson in 1974. Leadrubber bearings are another type of laminated elastomeric isolators. The purpose was to investigate the most favorable parameters of the lrb for. It was invented by william robinson, a new zealander.
This bearing consists of alternate horizontal layers of steel and. Earthquakes and the benefits of lead rubber bearing base isolation. The rubber compounds normally used in the production of lrb are characterised by an effective dynamic shear modulus g. Lead rubber bearing lrb lead rubber bearing lrb terdiri dari bantalan karet dan baja yang dilaminasi dengan pelat baja untuk pemasangan ke struktur. There are three main pieces of equipment, layers of steel plates, rubber layers and lead core, respectively. 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. Products seismic isolator for buildings bridgestone. A ucl civil engineering student workshop about earthquake engineering. The hysteretic behaviour of an lrb can also be modelled as linear, by means of the effective stiffness. Study of lead rubber bearings operation with varying. Many rubber based baseisolation techniques such as laminated rubber bearings, lead rubber bearings etc. Typical diagram of lead rubber bearing can be shown in figure 2. 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. 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.
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 mechanism of lead plug rubber bearings is very similar to that of lowdamping natural rubber bearings. These are the frequentlyused types of base isolation bearings. 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 base isolation system provides the combined features of vertical load support, horizontal flexibility, restoring force, and damping in a single unit. Lrb is a novel apparatus based on the combination of laminated layers rubber bearing using lead plugs constantinou, et al. The study presented in this paper aims to provide some clarification on the tensile response of lead rubber bearings by. If you continue browsing the site, you agree to the use of cookies on this website. The plasticization of lead permits to obtain an equivalent viscous damping coefficient up to approximately 30%.
By placing a thin lead sheet between the steel plates, it is possible to keep the plates from freezing together when they corrode. 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. Lead sheets are used to reduce corrosion between the plates, thereby providing more freedom of movement. Could lead rubber base isolators be the answer to our earthquake fears. The lead plug was forced in to the steel plates in the bearing deforms the shear.
Base isolation of residential building using lead rubber. Base isolation lead rubber bearing friction pendulum mining rubber. For nonlinear rubber bearing, bilinear forcedeformation properties including. Testing of high damping rubber bearings and lead rubber bearings for nuclear power plants maria gabriella castellano1, alberto dusi2 and alessandro poggianti3 abstract. A leadrubber bearing is formed of a lead plug force. Fhwa bridge inspection manual section 9 bridge bearings. Dynamic behavior of rc framed irregular building using. Lead rubber bearing consists of a laminated elastomeric rubber bearing equipped with lead cylinder at the centre of the bearing. The constitutive bond of lrb isolators is bilinear. Consider the reaction of a 16storey building on the seismic impact. Maurer lead rubber bearings mlrb are devices for seismic isolation.
Lead rubber bearing or lrb is a type of base isolation employing a heavy damping. 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. Pravat kumar parhi published on 20180508 download full article with reference data and citations. Required amount of damping can be produced by selecting the appropriate size of lead plug and also bearing provides elastic restoring force. However, in this type of bearing, the lead has a tendency to work its way out from between the plates. Lead rubber bearings as base isolating devices for the. Vertical stiffness of elastomeric and leadrubber seismic. Effectiveness of lead rubber base isolators, for seismic resistance of.
1335 1652 884 452 1410 727 1646 1300 273 322 454 422 391 671 609 731 1019 62 1458 1077 1591 304 195 1430 1271 1496 178 1207 300 1271 20 699