Effect of Shape Factor on the Seismic Performance of Elastomeric Bearings PDF Download
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Author: Adam Talmage Neill Publisher: ISBN: Category : Base isolation Languages : en Pages : 114
Book Description
Elastomeric bearings are increasingly becoming a design standard in the seismic isolation of large structures and buildings. The rubber bearings used in these designs are made of alternating layers of vulcanized natural or synthetic rubber and thin steel plates. These bearings are expensive to manufacture and are not applicable to smaller structures such as residential buildings. The idea of using inexpensive scrap-rubber tires for making base isolators for residential buildings has been proposed, but the performance of these bearings under seismic forces is not known. Shape factor is an aspect ratio term that is used in describing an elastomeric bearing's dimensional characteristics. Investigation into the performance of bearings with large shape factors has been extensive, but the performance of bearings with small shape factors has not been characterized. Theoretical modeling techniques employed for describing the behavior of rubber bearings with large shape factors are analyzed for the performance of bearings with small shape factors. Deflections of bearings with large shape factors are dominated by shear. As a bearing's shape factor decreases, the governing factor for the deflection changes from shear to bending. As the behavior of the bearing changes from shear to bending, different modeling techniques are necessary to analyze the system. The shape factor at which a bearing goes from shear to bending was established to be in the range of 0.15 to 0.30, which correlates well with theoretical predictions. It was additionally found that the theoretical modeling technique, used to describe the behavior of rubber in compression, is not adequate in predicting the performance of elastomeric bearings with small shape factors.
Author: Adam Talmage Neill Publisher: ISBN: Category : Base isolation Languages : en Pages : 114
Book Description
Elastomeric bearings are increasingly becoming a design standard in the seismic isolation of large structures and buildings. The rubber bearings used in these designs are made of alternating layers of vulcanized natural or synthetic rubber and thin steel plates. These bearings are expensive to manufacture and are not applicable to smaller structures such as residential buildings. The idea of using inexpensive scrap-rubber tires for making base isolators for residential buildings has been proposed, but the performance of these bearings under seismic forces is not known. Shape factor is an aspect ratio term that is used in describing an elastomeric bearing's dimensional characteristics. Investigation into the performance of bearings with large shape factors has been extensive, but the performance of bearings with small shape factors has not been characterized. Theoretical modeling techniques employed for describing the behavior of rubber bearings with large shape factors are analyzed for the performance of bearings with small shape factors. Deflections of bearings with large shape factors are dominated by shear. As a bearing's shape factor decreases, the governing factor for the deflection changes from shear to bending. As the behavior of the bearing changes from shear to bending, different modeling techniques are necessary to analyze the system. The shape factor at which a bearing goes from shear to bending was established to be in the range of 0.15 to 0.30, which correlates well with theoretical predictions. It was additionally found that the theoretical modeling technique, used to describe the behavior of rubber in compression, is not adequate in predicting the performance of elastomeric bearings with small shape factors.
Author: James M. Kelly Publisher: 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.
Author: Timothy R. Brown Publisher: ISBN: Category : ANSYS (Computer system) Languages : en Pages : 194
Book Description
The effects of shape and size on the performance of crumb-rubber base-isolation bearings were examined by use of a finite element model developed in ANSYS. Bearings tested were square, round, and annular. Base-isolation bearings are built by the lamination of alternating layers of steel and rubber. The steel prevents the rubber from bulging laterally and so increases the vertical stiffness while not effecting horizontal stiffness. This effect is controlled by the shape factor which is defined as the loaded area divided by the unloaded area. Shape factor acts within the individual layers of the bearing to control vertical stiffness, while overall bearing performance is controlled by the applied pressure and the total thickness of rubber. Factors contributing to bearing performance were analyzed individually. In particular, shape factor, overall thickness of rubber, and applied load were examined.
Author: Douglas K. Nims Publisher: ISBN: Category : Bridges Languages : en Pages : 346
Book Description
This report presents the results of tests and analyses performed on elastomeric bridge bearings. The focus of this research was the measurement of bearing deformations in the field and assessment of the feasibility of using instrumented elastomeric bearings to monitor bridge condition. The bearing deformations were successful measured in the field during the deck concrete pour and a static truck test. Shear, compression, rotation, and fatigue tests have been carried out in the laboratory and at the manufacturer's facility. Full scale bearings (shape factor 11) were tested at the manufacturer and installed in the field. Model bearings (shape factor 11 and one-quarter the plan area of the full scale bearings) were tested at the manufacturer and in the laboratory. Test bearings (shape factors 5,7, and 10) were tested in the laboratory. The bearing material was 50 Durometer neoprene. The analyses support the testing and considered the bridge-bearing system. The stiffnesses of the bearings are explicitly included in the analyses. A singular characteristic of this experimental research is the focus on the in-service behavior of the bearings.
Author: Joseph Vincent Muscarella Publisher: ISBN: Category : Bridges Languages : en Pages : 198
Book Description
The purpose of this study was to analyze elastomeric bearing performance on the basis of elastomer hardness, shape factor, reinforcing shim orientation, degree of taper and compressive stress level with the goal of developing a simple design procedure which standardizes as many of those parameters as possible. Particular emphasis was placed on comparing the behavior of flat and tapered bearings. Experimentation included shear, compressive, and rotational stiffness tests, shear and compression fatigue loading, long-term compressive loading, and tests to determine compressive stress limits.
Author: James M. Kelly Publisher: ISBN: Category : Buckling (Mechanics) Languages : en Pages : 74
Book Description
Presents findings of the theory for the buckling of elastomeric bearings based on assumption of linear relationship between the strain and stress in the rubber. The theory also predicts that the vertical stiffness of the bearing is strongly dependent on the shear deformation. Theoretical results are compared with a finite element analysis conducted on numerical models with various shape factors. The rubber material in the numerical models is assumed incompressible or almost incompressible and can undergo large deformations when the stress-strain relationship becomes significantly non-linear.
Author: Adam Talmage Neill
Author: Adam Talmage Neill
Author: Ian D. Aiken
Author: James M. Kelly
Author: Michael E. Doody
Author: 
Author: Timothy R. Brown
Author: Charles W. Roeder
Author: Douglas K. Nims
Author: Joseph Vincent Muscarella
Author: James M. Kelly