8/27/2019 Seismic Isolation Of Highway Bridges Pdf
Constantinou, M. Dicleli and H. Ghasemi MCEER-06-SP07 8/21/2006 190 pages About the Report: TOC: The is provided. Notes: A of this report is provided.
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Keywords: Seismic isolation. United States. Seismic protection. Seismic response. Structural performance. Elastomeric isolators. Sliding isolators.
Highway infrastructure. Seismic designs. Lead rubber bearings (LRB). Friction-pendulum isolator.
Eradiquake isolator. American Association of State Highway Transportation Officials (AASHTO). Energy dissipation. Abstract: More than 200 bridges have been designed or retrofitted in the United States using seismic isolation in the last 20 years, and more than a thousand bridges around the world now use this cost-effective technique for seismic protection. Intended to supplement AASHTO’s Guide Specifications for Seismic Isolation Design (1999), this manual presents the principles of isolation for bridges, develops step-by-step methods of analysis, explains material and design issues for elastomeric and sliding isolators, and gives detailed examples of their application to standard highway bridges.
Design guidance is given for the lead-rubber isolator, the friction-pendulum isolator, and the Eradiquake isolator, all of which are found in use today in the United States. Guidance on the development of test specifications for these isolators is also given.
Seismic Spring Mounts Andre HVAC International Inc (AHI) is a leader & consultant in the field of Seismic Vibration Isolation. AHI is manufacturing Seismic Vibration Isolators in Canada since 2003. AHI is providing complete range of products like Seismic Vibration Isolators for 1' deflection, Seismic Vibration Isolators for 2' deflection, Seismic cables, Seismic rod clamp etc. Seismic Isolators consist of heavy duty steel springs, Neoprene Snubbers & Steel Housing.
Function of Seismic Vibration Isolators. All seismic restraints are designed to withstand seismic forces of approximately 2G even at maximum rated load.
All seismic vibration Isolators are suitable & safe for most critical applications (including Zone 4 areas). The function of Seismic Vibration Isolators is to absorb vibration of rotating machines & restraints Seismic forces from all direction during earthquakes Application Of Seismic Restraints Seismic vibration isolators are used for absorbing vibration & restraints seismic forces for air handling units, centrifugal fans, pumps & chillers etc when these units are installed near seismic zones. Features Of Seismic Vibration Mounts. Built in leveling device in all different types of Seismic Isolators manufactured by AHI.
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Anti skid elastomeric acoustical pad is standard with all seismic restraints. Can be supplied Seismic vibration mounts with shipping block for OEM companies. Seismic restraints prevent damages of equipment & building from seismic forces created because of earthquakes & there by save a lot.
A study is made on the seismic behaviour of highway bridges with lead–rubber base isolation. The system of base isolation is considered as a bilinear spring. Single- and two-span highway bridges subjected to representative strong earthquake ground motion records were analyzed. The effect of various parameters such as the isolator's stiffness, pier stiffness, and pier eccentricity on the system response was evaluated.It was found that the use of base isolation shifts the fundamental frequency of the bridge system towards the longer period. Proper design of the base isolation tends to reduce the design forces on the bridge piers and is accompanied by larger displacements. Simplified design guidelines are adequate as long as the bridge system can be represented by a single degree of freedom model.
The reduction in pier stiffness of a two-span bridge may increase the displacement and the force transmitted to the abutment. The increased forces at the abutments are accompanied by reduction in the shear force transmitted to the pier. Increased displacements and forces may also result when the location of the pier departs from the centre and unequal spans are created.
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In this case, the maximum displacements and forces occur at the abutment adjacent to the long span. Key words: dynamic, seismic, response, highway, bridges, earthquake, base isolation, design.
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