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: Henan Mao Publisher: ISBN: Category : Languages : en Pages : 179
Book Description
Seismic isolation systems are becoming more common in the construction of a variety of critical buildings/facilities, such as hospitals and data centers, that require more stringent seismic performance levels. The Triple Friction Pendulum (TFP) isolation bearing systems offer arguably the highest performance among seismic hazard mitigation devices/solutions. TFP bearings, which exhibit highly nonlinear and history-dependent responses, dissipate the seismic energy through friction. While there are numerous models available to simulate the cyclic responses of TFP bearings, most either lack several key features, such as coupled biaxial or triaxial reactions or account for these effects in a phenomenological manner. The present study tackles these issues by implementing a physics-based, extendable, and numerically robust model, which is packaged into a novel macroelement that can be used in nonlinear time-history analyses that are required for performance-based seismic assessment and design. The aforementioned macroelement model is based on a mechanically consistent multi-surface plasticity approach that can simulate the triaxial hysteretic responses of TFP bearings. The macroelement model is developed and implemented in ABAQUS as a User-defined ELement (UEL). It is validated using experimental data from component-scale laboratory and full-scale shake table tests carried out at the E-Defense facility. The experimentally validated biaxial and triaxial TFP models are then used in performance-based seismic assessment of a prototypical base-isolated braced frame building to examine the effects of modeling errors on the estimated seismic losses. While the scope of this case study was limited to one building, findings indicated that differences between the basic (i.e., uncoupled biaxial) and the more advanced (i.e., coupled biaxial and triaxial) approaches are non-negligible, warranting their use in practice as well as future studies.
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: Henan Mao