Author: Gordon P. WarnPublisher:
ISBN:
Category :
Languages : en
Pages : 247
Book Description
A Study of the Coupled Horizontal-vertical Behaviour of Elastomeric and Lead-rubber Seismic Isolation Bearings
Author: Gordon P. WarnA Study of the Coupled Horizontal-vertical Behavior of Elastomeric and Lead-rubber Seismic Isolation Bearings
Author: Gordon P. WarnPublisher:
ISBN:
Category : Earthquake resistant design
Languages : en
Pages : 280
Book Description
The Coupled Horizontal-vertical Response of Elastomeric and Lead-rubber Seismic Isolation Bearings
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 312
Book Description
Elastomeric and lead-rubber bearings are two types of seismic isolation hardware widely implemented in buildings, bridges and other infrastructure in the United States and around the world. These bearings consist of a number of elastomeric (rubber) layers bonded to intermediate steel (shim) plates. The total thickness of rubber controls the low horizontal stiffness and the close spacing of the intermediate shims provides a large vertical stiffness for a given bonded rubber area and elastomer shear modulus. Conceptually, a lead-rubber bearing differs from an elastomeric bearing only through the addition of a lead-core typically located in a central hole. During earthquake ground shaking, the low horizontal stiffness of elastomeric and lead-rubber bearings translates into large lateral displacements, typically on the order of 100--200% rubber shear strain, that might lead to significant reductions in the axial load carrying capacity and vertical stiffness of the individual bearings. This dissertation presents an analytical and experimental investigation of the coupled horizontal-vertical response of elastomeric and lead-rubber bearings focusing on the influence of lateral displacement on the vertical stiffness. Component testing was performed with reduced scale low-damping rubber (LDR) and lead-rubber (LR) bearings to determine the vertical stiffness at various lateral offsets. The numerical studies included finite element (FE) analysis of the reduced scale LDR bearing. The results of the experimental and FE investigations were used to evaluate three analytical formulations to predict the vertical stiffness at a given lateral displacement. From component testing the vertical stiffness of the LDR and LR bearings was shown to decrease with increasing lateral displacement and at a lateral displacement equivalent to 150% rubber shear strain a 40--50% reduction in vertical stiffness was observed. One of the three analytical formulations, based on the Koh-Kelly two-spring model, was shown to predicted the measured reduction in vertical stiffness of the LDR and LR bearings at each lateral offset with reasonable accuracy. In addition, earthquake simulation testing was performed to investigate the coupled horizontal-vertical response of a bridge model isolated with either LDR or LR bearings. The results of simulations performed with three components of excitation were used to evaluate an equivalent linear static (ELS) procedure for the estimation of the vertical load due to the vertical ground shaking. The equivalent linear static procedure was shown to conservatively estimate measured maximum vertical loads due to the vertical component of excitation for most simulations.
Mechanics of Rubber Bearings for Seismic and Vibration Isolation
Author: James M. KellyPublisher: John Wiley & Sons
ISBN: 1119972809
Category : Technology & Engineering
Languages : en
Pages : 217
Book Description
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.
A Catalogue of the Genuine and Entire Collection of Limnings, Miniatures, Fine Antique Camŏs, Intaglias, Coins, Medals, and Other Curiosities of Mr. Robert Dingley, Sen. Late of Bishopgate-street, Goldsmith and Jeweller, Deceased
Author: Mechanics of Low Shape Factor Elastomeric Seismic Isolation Bearings
Author: Ian D. AikenPublisher:
ISBN:
Category : Bearings (Machinery)
Languages : en
Pages : 204
Book Description
Evaluation Findings for Skellerup Base Isolation Elastomeric Bearings
Author: Highway Innovative Technology Evaluation Center (U.S.)Publisher: ASCE Publications
ISBN: 9780784474570
Category : Technology & Engineering
Languages : en
Pages : 52
Book Description
Prepared by the Highway Innovative Technology Evaluation Center (HITEC), a CERF Service Center. This report summarizes the results of a detailedØevaluation of base isolation elastomeric bearings,Ømanufactured by Skellerup. The report is part of a program to test the performance of 11 seismic isolators and dampers produced by several manufacturers. The devicesØwere tested for stability, response during earthquake simulations, and fatigue and weathering effects.
Mechanistic Model for Lead Rubber Bearings
Author: Dipesh LalwaniPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Seismic isolation is a technique used to shift the fundamental period of a structure to a long range period which reduces the forces a structure attracts during a seismic event. Two, widely used bearings in seismic base isolation of structures are elastomeric and lead rubber bearings. A typical elastomeric bearing consists of a number of layers of rubber alternated with steel shims bonded between two rubber layers. The addition of a lead core inserted in a central mandrel hole results in a lead rubber bearing (LRB). The lead enhances the bearings energy dissipating in an earthquake event. When elastomeric or LRBs are simultaneously subjected to vertical compressive load and increasing lateral displacement, the shear force equilibrium path can exhibit a critical point, beyond which the bearing exhibits negative stiffness. Semi-empirical models to simulate this behavior for elastomeric and LRB have been developed in the past. These models rely on experimentally calibrated parameters, making them impractical for design. Recently, a particular mechanics based model, developed for an elastomeric bearing only, approaches the modelling using vertical springs and a simple bi-linear constitutive relationship to represent the rotational behavior of an elastomeric bearing. Overarching goal of the present study is to build on the mechanics based elastomeric model to develop a LRB model. The elastomeric model is modified to include hysteretic behavior of LRB and also uses a Newton type numerical solution technique to solve for response of the bearing. The model, proposed in this study, utilizing vertical springs approach has shown to be capable of simulating the strength, stiffness and hysteretic behavior of LRB well.
Design of Seismic Isolated Structures
Author: Farzad NaeimPublisher: John Wiley & Sons
ISBN: 9780471149217
Category : Technology & Engineering
Languages : en
Pages : 308
Book Description
Um die Auswirkungen von Erdbeben auf Gebäude, Brücken und andere empfindliche Konstruktionen zu mildern, wurden im Laufe der Jahre zahlreiche Technologien entwickelt. Eine der neueren hiervon ist die seismische Isolation: Sie beinhaltet den Einbau von Mechanismen, die das Gebäude von den Bewegungen des Untergrunds entkoppeln. Der Erfolg dieser Technik übertrifft den aller vorher bekannten Verfahren - ein Grund für Ingenieure und Architekten, sich genauer zu informieren. Dazu sei dieses Buch empfohlen. (04/99)
Dynamic and Failure Characteristics of Bridgestone Isolation Bearings
Author: James M. KellyPublisher:
ISBN:
Category : Base isolation
Languages : en
Pages : 100
Book Description