Steel bridge bearing design and detailing guidelines section 1 elastomeric bearings 1. July 2019 276 the required design input for the design of an elastomeric bearing at the service limit state is dead load, live load plus dynamic load allowance, minimum vertical force due to permanent load, and design translation. These changes to the top bearing plate design shall apply to both non elastomeric and elastomeric top bearing plate designs. Design charts for eurocodebased design of elastomeric seismic isolation systems article pdf available in soil dynamics and earthquake engineering january 2018 with 300 reads. Key words elastomeric bearing, field investigation.
Delivering quality at every stage, all bridge bearings are designed individually to exacting standards using high specification materials from approved sources. In situations where the bridge skew exceeds 30 degrees, consult the bearing and expansion joint. Design, manufacture and subsequent national association of testing authorities ilac mra certified testing of granor elastomeric bearings is to recognised australian and international standards. Reinforced elastomeric bearing pads, designed in accordance with bridge design. Both rocker and pin bearings are mainly employed in steel bridge structure. Reinforced elastomeric bearings are an often used type of bridge bearings and already been installed in many kinds of structures all over the world. Arrangements should be made at the design stage for providing sufficient clea. Compared to other types of bearings, they are easy to install, have a long life expectancy 100 years plus and are maintenance free. Metallic bonded shims, thickness a a plan elastomeric bearing pad l w d e s ig n a ti o n b e a ri n g w width bearing l length bearing. Bridge bearings introduction aashto defines a bearing as a structural device that transmits loads while facilitating translation andor rotation. Nchrp project 1020 was initiated at the university of washington in 1981 with the objective of developing design, construction, and materials specifications for unconfined, plain and reinforced, elastomeric, bridge bearings, and this report contains the findings of that study.
Elastomeric bearing design example strength of materials. The bearings may be designed by either method a article 14. Lrfd steel girder superstructure design example bearing design example design step 6 table of contents design step 6. This engineering manual has been prepared based on the companys many years of experience in manufacturing and installing thordon bearing products worldwide. Method a is the required design procedure for plain. Rocker and pin bearing should be considered when the bridge movement is adequately known and described, since such bearings can make rooms for both translational and rotational movements in one direction only. Design step steelreinforced elastomeric bearing design 6. It is intended for use by persons having technical training and skill, at their discretion and risk. Elastomer may be used as a plain pad pep or may be reinforced with steel. It provides a single source for aashto and mdot policy information related to the design, fabrication, material, and testing of elastomeric bearings plain and reinforced used on mdot projects. Design elastomeric bearings for service loads and without dynamic load allowance im.
Because bearing rotation was not considered a highpriority issue at that time, the design provisions that were developed were based upon conservative. Under nchrp project 1051, the university of texas at austin addressed these concerns. Typical steel reinforced elastomeric bearing the design of a steel. These changes to the top bearing plate design shall apply to both nonelastomeric and elastomeric top bearing plate designs. Va n c l e a v e 9750 plus the two external layers thickness. Designed and sized to meet the needs of your structure, these bearings are rigid enough to transmit the necessary loads and flexible enough to permit the rotation and movement required by the structure. Elastomeric bearings can absorb horizontal movements in every direction and rotational movements around. Elastomeric bearings goodco ztech elastomeric bearings are fabricated of natural rubber or neoprene. Maurer elastomeric bearings are available made of natural or chloroprene rubber from inhouse production and mixture. A laminated elastomeric bearing is an elastomeric rubber. Design step 6 design of bearings prestressed concrete.
It is a monolithic structure ob tained by vulcanization of the rubber pad and external steel plates. Previous elastomeric bearing design provisions were developed in nchrp project 1020. When required design load or movement exceed the limits of the standard elastomeric bearings given below, the elastomeric bearings shall be specially designed or multirotational bearings shall be used. Bearing design spread sheet based on aashto 16th edition 1197. Bridge bearing rubber sheeting is manufactured from a high performance natural rubber nr that is suitable for use as an elastomeric bridge bearing pad when converted from the sheet. Laminated elastomeric bearings can be fitted with a sliding surface comprising a ptfe polytetrafluoroethylene sheet dipped in the elastomer of the bearing or notched in the top thick outer plate and a sliding plate provided with an austenitic steel sheet for decks requiring significant movement. Around this makeup a rubber cover encapsulates the bearing fig. Specifications, section 14, should be considered the preferred type of. Read design guide for bridges for service life at nap. If the loads were considerably larger, pot bearings, which are more expensive than elasomeric bearings, would be an option. They can be designed to transmit vertical and horizontal forces from the superstructure to the substructure, without constraints. Design bearings for movements associated with a temperature range of 150 f 30 f to 120 f and a base construction temperature of 45 f.
Design example 3 appendix a example 3 type i bearing steel reinforced method b general information material and section properties bearing dimensions bearing width w 20. In the next step, vibration isolator that was designed is manufactured using the elastomeric material chosen, by a local rubber company. Then, according to design requirements, final design parameters of the vibration isolator are determined at the end of design iterations. In case the horizontal displacements exceed the design limits of the elastomeric bearing, an additional sliding plate permits displacements without shear deformation of the bearing.
These items are then vulcanised to create a compact maintenance free bearing. The adopted elastomeric bearings is of type b with outer steel plate of ks exhibiting a shear modulus of 0. The following sections and the design example below are based on method b. Elastomeric bearing design example elastomeric bearing design. Bearings and expansion joints chapter 9 wsdot bridge design manual m 2350. Bearing design spread sheet based on aashto 16th edition. Bridge design specifications, section 14, should be considered the preferred type of bearing for all structures. Elastomeric bearings for steel trapezoidal box girder bridges. Aashto design allows elastomeric bearings to be designed based on one of two methods. Flowcharts for the bearing design using both method a and method b are included in section 3. Semiintegral construction may be used in lieu of expansion joints for single span bridges under 300 feet with the approval of the bridge design engineer. This information is offered as part of our service to customers. The second one is a new bearing that supposed to be replaced with the old one. The structural bearing is the key element that creates freedom of movement between a structure and its foundation while ensuring the transfer of vertical loads and rotation.
Plain and laminated steel reinforced elastomeric bearings can be designed by. Denver, colorado e general objective of this project was the determination of. Around this makeup a rubber cover encapsulates the bearing. The required design input at the strength limit state is shear force. Elastomeric bearings can absorb horizontal movements in every direction and rotational movements around every axis through elastic. Elastomeric bridge bearing design design spreadsheet based on aashto 16th edition 1197 interim method a aashto lrfd bearing type p plain r reinforced r bearing type f fixed, e expansion e fos 1. Design example 1 appendi exampl 1 astomeric evelin d. The results of this program are contained in the following four volumes. The following zipped file contains mathcad worksheets that analyze and design elastomeric bridge bearings in accordance with the aashto lrfd specifications 2012 with 20 interim revisions. Bridge bearings types of bearings for bridge structures and. For this an anchor plate will be vulcanised onto the bearing upper and lower surface. Depending on the area of application and country requirements maurer elastomeric bearings can be supplied in accordance with various standards, e. Behavior and design of selected elastomeric bearing pads leonard tulin professor of civil engineering department of civil, environmental and architectural engineering university of colorado boulder.
Past manual notices are available in a pdf archive. Structural design elastomeric bearings bearings are normally mounted with their short side parallel to the girder axis for maximum rotation capacity. For the abutment bearing design, a steelreinforced elastomeric bearing was selected. However orientation at any angle in the horizontal plane will not affect the shear resistance. Ccls quality management system complies with en iso 9001. The products of this effort are a design manual and a computer program based on finite element techniques.
Also, top bearing plates shall be designed using reduced c values of 0. Lrfd steel girder superstructure design example lrfd. Friction is usually sufficient to keep bearings in place, but if minimum loads are. Bridge bearings types of bearings for bridge structures. These include rockers, rollers, pins, pots, steel girder hangers, ptfeelastomeric, and elastomeric pads. The information included is intended to permit efficient fabrication, installation, and maintenance of these bearings. Use ltype abutments with expansion joints at the ends for multiplespan bridges. Structures design and analysis programs new york state. Design of elastomeric bearings is typically the responsibility of the design engineer whereas the manufacturer performs the design of most highload multirotational hlmr bearing assemblies.
The latest design software and fea is used to optimise bearing design for efficiency and cost. It consists of elastomer manufactured from synthetic or natural rubber and can take both translation and rotation movements through elastomer deformation. The data contained in this report are the results of an effort designed to improve the state of the art of elastomeric bearing design for helicopter rotor head. The design of an elastomeric bearing generally involves the following steps. Steel bridge, bearings, elastomeric bearing, highload. An elastomeric concrete material acts as the load bearing surface and the component that allows free expansion and contraction. For skewed bridges the distribution factor for shear may be modified by multiplying it. Bearing 2 detailed design report adopted 5 laminates with 4 internal layers 80 mm total thickness of elastomeric pad shape factor 9. Example 1 elastomeric leveling pad method a 2 21 bridge geometry profile grade between supports % 1. A series of elastomeric bearings were designed and fab ricated in compliance with ks. Steel reinforced elastomeric bearings become large if they are designed for loads greater than about.
The rectangular elastomeric bearing pad shall be placed with l notes. Elastomeric bearing design example universitas brawijaya. Reinforced elastomeric bearing pads, designed in accordance with. Plain pads, steel reinforced and cotton duck elastomeric bearings are the three predominant. Oct 06, 2009 previous elastomeric bearing design provisions were developed in nchrp project 1020. Behavior and design of selected elastomeric bearing pads. Steel bridge design handbook bearing design volume 15. With our extensive design experience we can readily provide designs for specialty applications to meet unique design criteria or specific design requirements. Design example 3 colorado department of transportation. In the past, only the parameter of hardness have been used for elastomeric bearing pads, but nowadays the. The typical hinge or abutment configuration using many small elastomeric bearing pads has proved highly reliable and. The goal of this study is to study the condition of bearings which are in use, determine the common physical symptomsproblems having to do with age, design or weather condition and through these findings determine the cause of ill performing bearings. Finally, design process is verified by comparing analysis and test results. Pdf design charts for eurocodebased design of elastomeric.
On request, we supply bearings with other shear moduli and according to requirements of the project or other standards, e. Granor supplies bearings in accordance with australian standard as5100. Design guidelines for elastomeric bearings elastomeric bearings shall consist of either plain elastomeric pads or steelreinforced laminated pads. If tests that are accurate and essential predictors of.
Experimental study on the ultimate shear performance of. Laminated elastomeric bearings consist of natural rubber layers separated by steel plates. Laminated elastomeric bearings can be fitted with a sliding surface comprising a ptfe polytetrafluoroethylene sheet dipped in the elastomer of the bearing or notched in. This joint system has been installed in selected pilot bridges on secondary roads for observation.
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