The bridge modeler locates bearing links directly below the girder web. Small displacements are absorbed by the rubber itself, while large displacements cause the rubber bearing to slide on the plate. Clayton building, toe toe bridge, and waiotukupuna bridge. Tutorial 1, tutorial 2 modeling of seismic isolators in contemporary software programs. It is very soft laterally but very stiff vertically. Manish kumar start indian institute of technology bombay. Engineering sciences mechanical properties of rubber an overview al. Lead rubber bearing properties in sap2000 input your data in input sheet and get outputs in sap2000 sheet. It was invented by william robinson, a new zealander. Technical parameters of base isolator also is required to be identified. Leadrubber bearing prototype testing canam bridges. Typical leadrubber bearing courtesy dis the energy dissipation capacity, or damping, is governed by the plastic deformation. No need to provide nonlinear property of isolator in rsa, it is needed in fna. First, the mechanical properties for lrb isolation system are calculated.
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. 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. Leadrubber bearings with emphasis on their implementation. For the various link objects available, forcedeformation relationships may be defined along each degreeoffreedom dof, including axial, torsional, major and minor shear, and major and minor bending. Since all components are vulcanized inside the rubber, no special maintenance is required beyond that of laminated bearings. Study on the impact of leadrubber bearing parameters on. Robinson wh, tucker ag 1983 test results for leadrubber bearings for the william m. Application of seismic isolation elastomeric bearings in highway bridges is a novel approach, which helps in reducing the earthquake forces considerably. Products seismic isolator for buildings bridgestone.
Bridge bearings technical knowledge base computers and. Rubber bearing,natural rubber bearings,industrial rubber. In the present study, a periodic structure model along with tmm, because of its simplicity, is developed to solve the mechanical properties of laminated rubber bearings. The base isolation device used is lead rubber bearing lrb for seismic zone v and hard rock soil, the analysis performed. The steel shims provide vertical stiffness to the lrb and layers of rubber provide lateral flexibility or horizontal stiffness. Here is a decent calculator for that property the sagulator. So the bearing materials should be both strong and soft.
Lead rubber bearing is regarded as one of the most popular isolators used in structural control. Alibaba elastomeric bearing pad,rubberpvc water strip. Lead rubber isolation bearing lrb is used in the examination. Comparative behavior of structure with and without base. Pdf effect of lead rubber bearing characteristics on the. Isolation bearings, seismic isolators, isolation in india, isolation, base isolation,seismic isolation,dynamic isolation systems,dis,konrad eriksen,bridge retrofit,historic building retrofit,earthquake. Effectiveness of lead rubber base isolators, for seismic resistance of. An equivalent linear model for the seismic analysis of baseisolated bridges with leadrubber bearings lrb is established in this paper using an identification method. To model a different bearing layout, delete the links automatically created, then, outside. This report summarizes the modeling techniques of elastomeric and frictionbased isolators in sap2000, abaqus, lsdyna, and.
Analysis of mechanical properties of laminated rubber. Design of leadrubber bearings for use in seismic isolation of highway bridges. Development of a friction pendulum bearing base isolation. Development of a friction pendulum bearing base isolation system for earthquake engineering education nikolay kravchuk1, ryan colquhoun1, and ali porbaha2 california state university, sacramento, ca abstract base isolation systems have become a significant element of a structural system to enhance reliability during an earthquake. Pushover analysis features in sap2000 include the implementation of fema 356 and the hinge and fiber hinge option based on stressstrain. The model is formulated according to haringxs theory for the rubber layer, while the steel shims are considered as rigid body. To study the effect of using lead rubber bearing on the. Abec tolerance classes are useful in bearing selection. Try my web application for design of lr bearing video tutorials on blast load calculation tool air3d.
During any sudden load, seismic, braking, train acceleration, ship collision or any other force acting on the bridge that would cause the bridge to move suddenly, the lud becomes a rigid link and the forces are then transmitted through the structure. Design and characteristics of high damping natural rubber. This type of isolator provides a good balance between damping and cost. A wide variety of lead rubber bearing options are available to you, such as single row. Seismic retrofit of piers supported on battered piles.
A lead rubber bearing is a much larger laminated bearing manufactured from layers of rubber which are sandwiched together with layers of steel and in the middle of the bearing there will be a. Lead has a low shear strength, and is able to fill in. Vertical stiffness of rubber bearing is given by composite compression modulus now, from above calculation summary of lead rubber bearing design for symmetric building is as shown in table table 1. 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. More than 250 buildings and bridges are protected from earthquakes by dis seismic isolators. Research paper excel spreadsheet for design of lead. Lead rubber bearing properties help desk software by jitbit. Seismic retrofit of piers supported on battered piles using leadrubber bearings. A bearing material should have structural uniformity and its properties should not change as surface layers wear away. Properties of lead lead has the advantages of low melting temperature and extreme malleability, which allow easy casting, shaping and joining of lead articles. Dynamic properties of lead rubber bearings and its seismic.
The seismic response analyses of piers isolated by lrb in axial direction of the bridge are carried out under the excitations of seven earthquake waves. Effect of lead rubber bearing characteristics on the. Civilax based to server in civil engineering provides etabs and sap2000 tutorials, civil engineering spreadsheets, civil engineering ebooks and many more civil engineering downloads. In the attached screen shot, in the linear properties the stiffness is defined as 336. In addition, it was performed the evaluation of the seismic behaviour of the isolated structure. Twospring model of an isolation bearing in the undeformed and deformed configuration. The seismic analysis of the buildings is executed by nonlinear time history analysis method for reinforced. Besides this lead is slow to corrode and there are many examples of lead articles which have lasted. Overwrite options are located under brim bridge object abutments and bents. Lead rubber bearing or lrb is a type of base isolation employing a heavy damping. The typical hysteresis loop of a lead rubber bearing can be modelled as bilinear. Several studies have been carried out to reuse scraptires in a variety of rubber and plastic products, incineration for production of electricity.
Based on the finite element program sap2000, 120 models of eight different piers with different leadrubber bearings lrb are established. A ucl civil engineering student workshop about earthquake engineering. For leadcore can dissipate seismic energy and increase stiffness under load simultaneously, and most of the requirements of the seismic. I do not work in sap2000 but wood has different qualities by species just like metals by alloy. The purpose was to investigate the most favorable parameters of the lrb for minimum earthquake response of the isolated bridge system for different ground motions. 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. However, abec classes are not allinclusive in defining bearing precision. Design and characteristics of high damping natural rubber bearings for base isolation k. Lead core rubber bearings lrb consists of a laminated rubber and steel bearing with steel flange plates for mounting to the structure. 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.
Dynamic isolation systems dis is the leader in the seismic isolation of bridges and buildings. Application of lead rubber isolation systems in the. Effectiveness of lead rubber base isolators, for seismic. Research paper excel spreadsheet for design of lead rubber bearing uses for seismic isolation of bridges chauhan kalpesh m. If you continue browsing the site, you agree to the use of cookies on this website. Common name neoprene natural polyisoprene butyl chlorinated butyl buna n sbr hypalon vamac ethylene propylene rubber polyethylene teflon crosslinked polyethylene modified crosslinked polyethylene composition name chlorprene. Leadrubber bearings were chosen for the seismic isolation of these bridges. Ninety percent of our isolators have an energy dissipating lead core. Dynamic isolation systems installation of lead rubber. The calculations of seismic responses of the piers with and without isolation are implemented by using. Excel user should know complete excel tutorial hindi duration. The components of the lrb are lead plug, endplates, steel shims and rubber layers. The nonlinear layered shell element enables users to consider plastic behavior of concrete shear walls, slabs, steel plates, and other area finite elements in the pushover analysis.
Bearing performance and life can be affected by factors other than abec contded characteristics. I am trying to understand midas input for the lead rubber bearing properties. One property is sag weight it can carry over a given span and how much it will deflect. These rubber bearings are widely acceptable because of their longevity, economy and better control on dynamic properties. On the other hand, alloys such as the leaded bronzes are used because they provide a lubricating film of lead at the bearing journal interface. Base isolation on sap2000, how do i determine the effective damping of a nllink. Lead rubber bearing parameters items design values diameter of rubberm 0. The rubber compounds normally used in the production of lrb are characterised by an effective dynamic shear modulus g. By specifying abec 7, for example, the design engineer is able to pinpoint a standardized level of beanng precision. In this implementation, the linear shear spring has been replaced by a bilinear spring to represent the nonlinear behavior observed in elastomeric and leadrubber bearings ryan et. 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. Skinner ri, robinson wh, mcverry gh 1993 an introduction to seismic isolation. These properties may be specified to simulate the behavior desired of bearings, isolators, soil springs, and other structural. Application of lead rubber isolation systems in the offshore structures habib saeed monir, hiva nomani.
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