Finite Element Modeling of the Effect of Shape and Size on the Performance of Crumb-rubber Base-isolation Bearings PDF Download
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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: 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: 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: Kasey Ketterling Publisher: ISBN: Category : Base isolation Languages : en Pages : 206
Book Description
Dynamic and static tests were performed on hollow-core seismic base isolation bearings constructed from crumb-rubber composite from recycled tires to determine if the behavior of bearings from this new material performed according to existing theory. The effects of weight, height, acceleration, particle shape, and intermittent plates were analyzed to develop trends in the behavior of bearings. Crumb rubber from recycled tires had not been previously considered as a structural material, necessitating a thorough material classification. In the horizontal direction under dynamic loading, the bearings performed according to theory, with minimal error likely due to material inconsistencies. The behavior in the vertical direction was less predictable. Taller bearings were considered for this testing then recommended by current practice, with the introduction of non-linear effects, such as bending and non-parabolic deformation under vertical loading. The results obtained will be useful in making advancements towards using crumb-rubber composite from recycled tires in seismic base isolation bearings in residential construction.
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: Publisher: ISBN: Category : Languages : en Pages : 200
Book Description
Aseismic design is the art and science of designing structures to withstand the forces they are subjected to in the event of an earthquake. Modern aseismic designs include the use of energy absorbing devices which are not permanently deformed when activated by earthquake motions. Analytical prediction of the response of these highly nonlinear systems to earthquake motions requires significant idealizations of the material, component, and structural behavior, and is not fully developed for all structural systems. Thus, to understand and evaluate the global behavior of structural systems with these aseismic devices, one needs to perform physical testing of complete structures subjected to earthquake motions. Because of the size limitations and expense of seismic simulators (shake tables) available and the need to test complete structures, small-scale models are often the only choice for testing. This research is an attempt to develop a procedure for designing and fabricating small scale models of base isolators which act as a passive control devices. Scale models of the laminated rubber bearings (with steel plates) and laminated rubber bearings with lead core are fabricated. A procedure to determine the stiffness properties and coefficient of damping for these bearings is presented in this study. An experimental procedure to study the effect of these bearings on the dynamic response of a 1/24 scale single story model test frame subjected to sinusoidal ground motions is also presented. The experimental results for the horizontal stiffness and coefficient of damping are regressed to formulate prediction equations which are used to develop a mathematical spring-dashpot damper model for the base isolators. The developed mathematical model is then validated by comparison of dynamic response of the test frame to sinusoidal ground motion obtained from the frame analysis using SAP 2000, version 10.0. The application of the mathematical model to a model frame subjected to scaled earthquake ground motion is also demonstrated. This part of the study is undertaken since the shake table used for testing could not simulate an actual earthquake ground motion. The displacement and acceleration responses of the test frame without and with the laminated rubber bearings and lead core rubber bearings when subjected to actual scaled earthquake ground motion record are investigated to evaluate the performance of each type of bearing as a base isolation system.
Author: Highway Innovative Technology Evaluation Center (U.S.) Publisher: ASCE Publications ISBN: 9780784474563 Category : Technology & Engineering Languages : en Pages : 56
Book Description
Prepared by the Highway Innovative Technology Evaluation Center (HITEC), a CERF Service Center. This report summarizes the results of a detailedØevaluation of high-damping rubber bearings,Ømanufactured by Scougal Rubber Corporation. 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.
Author: Bridger D. Morrison Publisher: ISBN: Category : Elastomers Languages : en Pages : 118
Book Description
Elastomeric base isolation systems are currently limited to large and expensive structures. The application of such systems in other, smaller structures, such as residential buildings, depends upon the ability to reduce the cost while maintaining the functionality with the corresponding lighter loads. Compression testing was performed on super-soft neoprene rubber of five different hardnesses to determine the mechanical properties of the elastomer. Based on the compression testing results, base isolation bearings were fabricated with fiberglass mesh fabric layers to increase the vertical stiffness of the bearings. Two sample sets were produced to determine the effect of the material hardness in the performance of the bearings under horizontal dynamic testing. Dynamic testing was performed on both sample sets under three loading and two base-line acceleration conditions, totaling twelve dynamic tests. The dynamic testing revealed that the horizontal natural frequencies were lower than that predicted by theory. In addition, the stiffness of the bearings decreased as the loads increased. The actual effect that the rubber hardness had on the performance of the bearings was smaller than the theory predicted. The dynamic testing indicated that it may be possible to produce low-cost bearings with a horizontal stiffness low enough for residential building construction.
Author: Timothy R. Brown
Author: Timothy R. Brown
Author: Adam Talmage Neill
Author: Kasey Ketterling
Author: Ian D. Aiken
Author: James M. Kelly
Author: 
Author: Highway Innovative Technology Evaluation Center (U.S.)
Author: Chan Ghee Koh
Author: Chong-shien Tsai
Author: Bridger D. Morrison