Seismic Design of Base-isolated Highway Bridges Utilizing Lead-rubber Bearings

Seismic Design of Base-isolated Highway Bridges Utilizing Lead-rubber Bearings
Author:
Publisher:
Total Pages: 10
Release: 1990
Genre:
ISBN:

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A study is made of the seismic behaviour of base-isolated highway briges with the objective of developing design procedures in the form of code-type approach. The recommendations of current codes concerning the use of energy dissipation mechanisms for the seismic design of bridges are reviewed. A model representing the bridge deck, piers, and the base-isolation system is used to evaluate the response of the bridge to a selected earthquake time history record and to evaluate the effects of various design parameters on the dynamic response. The results of this analysis are used in the development of design guidelines for the isolated bridge system. It was found that base isolation affects the design forces on piers and abutments as well as the deck displacements. An optimum design should provide a reasonable balance between the shear forces on supports and tolerable displacements. Two design procedures are proposed based on the time history and inelastic response spectra approaches. Simplified charts are presented which aid in the seismic design of new bridges as well as in the upgrading of existing ones.

Guide Specifications for Seismic Isolation Design

Guide Specifications for Seismic Isolation Design
Author:
Publisher: AASHTO
Total Pages: 63
Release: 2010
Genre: Technology & Engineering
ISBN: 1560514566

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This edition is based on the work of NCHRP project 20-7, task 262 and updates the 2nd (1999) edition -- P. ix.

Guide Specifications for Seismic Isolation Design

Guide Specifications for Seismic Isolation Design
Author: American Association of State Highway and Transportation Officials
Publisher:
Total Pages: 36
Release: 1999
Genre: Technology & Engineering
ISBN:

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Mechanics of Rubber Bearings for Seismic and Vibration Isolation

Mechanics of Rubber Bearings for Seismic and Vibration Isolation
Author: James M. Kelly
Publisher: John Wiley & Sons
Total Pages: 217
Release: 2011-08-24
Genre: Technology & Engineering
ISBN: 1119972809

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Widely used in civil, mechanical and automotive engineering since the early 1980s, multilayer rubber bearings have been used as seismic isolation devices for buildings in highly seismic areas in many countries. Their appeal in these applications comes from their ability to provide a component with high stiffness in one direction with high flexibility in one or more orthogonal directions. This combination of vertical stiffness with horizontal flexibility, achieved by reinforcing the rubber by thin steel shims perpendicular to the vertical load, enables them to be used as seismic and vibration isolators for machinery, buildings and bridges. Mechanics of Rubber Bearings for Seismic and Vibration Isolation collates the most important information on the mechanics of multilayer rubber bearings. It explores a unique and comprehensive combination of relevant topics, covering all prerequisite fundamental theory and providing a number of closed-form solutions to various boundary value problems as well as a comprehensive historical overview on the use of isolation. Many of the results presented in the book are new and are essential for a proper understanding of the behavior of these bearings and for the design and analysis of vibration or seismic isolation systems. The advantages afforded by adopting these natural rubber systems is clearly explained to designers and users of this technology, bringing into focus the design and specification of bearings for buildings, bridges and industrial structures. This comprehensive book: includes state of the art, as yet unpublished research along with all required fundamental concepts; is authored by world-leading experts with over 40 years of combined experience on seismic isolation and the behavior of multilayer rubber bearings; is accompanied by a website at www.wiley.com/go/kelly The concise approach of Mechanics of Rubber Bearings for Seismic and Vibration Isolation forms an invaluable resource for graduate students and researchers/practitioners in structural and mechanical engineering departments, in particular those working in seismic and vibration isolation.

SEAOC Blue Book

SEAOC Blue Book
Author:
Publisher:
Total Pages: 256
Release: 2009
Genre: Building laws
ISBN: 9781936039036

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This SEAOC Blue Book: Seismic Design Recommendations is the premier publication of the SEAOC Seismology Committee. The name Blue Book is renowned worldwide among engineers, researchers, and building officials. Since 1959, the SEAOC Blue Book, previously titled Recommended Lateral Force Requirements and Commentary, has been a prescient publication of earthquake engineering. The Blue Book has been at the vanguard of earthquake engineering in California and around the world. This edition of the Blue Books offers a series of articles, that cover specific topics, some related to a particular code provision and some more general relating to an area of practice. While different than the previous editions of the Blue Books, it builds upon the tremendous effort of those who have forged earthquake engineering practice via the previous half-century of Blue Book editions. The Blue Book provides: insight and discussion of earthquake engineering concepts; interpretations of sometimes ambiguous or conflicting provisions of various codes, standards, and guidelines; and practical guidance on design implementation.

Design, Analysis, and Seismic Performance of a Hypothetical Seismically Isolated Bridge on Legacy Highway

Design, Analysis, and Seismic Performance of a Hypothetical Seismically Isolated Bridge on Legacy Highway
Author: Keri Lynn Ryan
Publisher:
Total Pages: 208
Release: 2011
Genre: Bridges
ISBN:

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The need to maintain the functionality of critical transportation lifelines after a large seismic event motivates the strategy to design certain bridges for performance standards beyond the minimum required by bridge design codes. To design a bridge to remain operational, one may stiffen and strengthen the load carrying members to increase the capacity, or alternatively use response modification devices such as seismic isolators to shift the dynamic characteristics of the bridge, henceforth reducing the seismic demands. Seismic isolation systems are attractive because they are directly conducive to accelerated bridge construction techniques. The two strategies are compared for a typical Utah highway bridge, using a three-span, pre-stressed concrete girder bridge that crosses Legacy Highway as a case study example.

Seismic Protection of Bridge Structures Using Shape Memory Alloy-based Isolation Systems Against Near-field Earthquakes

Seismic Protection of Bridge Structures Using Shape Memory Alloy-based Isolation Systems Against Near-field Earthquakes
Author: Osman Eser Ozbulut
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN:

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The damaging effects of strong ground motions on highway bridges have revealed the limitations of conventional design methods and emphasized the need for innovative design concepts. Although seismic isolation systems have been proven to be an effective method of improving the response of bridges during earthquakes, the performance of base-isolated structures during near-field earthquakes has been questioned in recent years. Near-field earthquakes are characterized by long period and large- velocity pulses. They amplify seismic response of the isolation system since the period of these pulses usually coincides with the period of the isolated structures. This study explores the feasibility and effectiveness of shape memory alloy (SMA)-based isolation systems in order to mitigate the response of bridge structures against near-field ground motions. SMAs have several unique properties that can be exploited in seismic control applications. In this work, uniaxial tensile tests are conducted first to evaluate the degree to which the behavior of SMAs is affected by variations in loading rate and temperature. Then, a neuro-fuzzy model is developed to simulate the superelastic behavior of SMAs. The model is capable of capturing rate- and temperature-dependent material response while it remains simple enough to carry out numerical simulations. Next, parametric studies are conducted to investigate the effectiveness of two SMA-based isolation systems, namely superelastic-friction base isolator (S-FBI) system and SMA/rubber-based (SRB) isolation system. The S-FBI system combines superelastic SMAs with a flat steel-Teflon bearing, whereas the SRB isolation system combines SMAs with a laminated rubber bearing rather than a sliding bearing. Upon evaluating the optimum design parameters for both SMA-based isolation systems, nonlinear time history analyzes with energy balance assessment are conducted to compare their performances. The results show that the S-FBI system has more favorable properties than the SRB isolation system. Next, the performance of the S-FBI systems is compared with that of traditional isolation systems used in practice. In addition, the effect of outside temperature on the seismic response of the S-FBI system is assessed. It is revealed that the S-FBI system can successfully reduce the response of bridges against near-field earthquakes and has excellent re-centering ability.