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: Cong Sun (Ph. D.) Publisher: ISBN: Category : Languages : en Pages : 422
Book Description
Steel laminated elastomeric bearings are widely used in concrete bridges due to their low cost and long history of good structural performance. However, elastomeric bearings have not been used extensively in steel bridge systems. Compared to concrete bridges, steel bridge systems generally have longer spans and may have significant support skew and horizontally curved geometry that results in significant demands on the bearings at the supports to accommodate rotations and complex bridge movements from both thermal loads and daily truck traffic. For such bridges, more costly pot bearings are normally used. The research described in this dissertation was part of a larger study investigating the possibility of using elastomeric bearings in such higher demand applications. More specifically, the research in this dissertation investigated issues related to material properties of the elastomer in larger bearings designed for higher demand applications. This dissertation first introduces a new testing methodology, referred to as the Dual Shear Test (DST), which is able to measure the elastomer material response in shear for samples cut directly from of bearings with different dimensions. The proposed geometry of the DST specimen significantly reduces the cost and effort compared to the more conventional Quad Shear Test, and also allows the measurement of shear response at very large shear strain levels. Based on a systematic experimental study, the accuracy and reliability of this new testing methodology was demonstrated. Different hyper-elastic material models were investigated in this dissertation that can be used in finite element studies of elastomeric bearings. These models were calibrated based on the new shear test methodology. With these material models, DST results can be interpreted and entered into finite element models. Using the Dual Shear Test, four bearings of different dimensions were tested. The variability of the shear modulus at different locations within the bearings was investigated. These tests were conducted to address concerns that larger bearings may have greater variability in elastomer material properties throughout the bearing. These tests showed there is somewhat greater variability in shear modulus in larger bearings and thicker bearings, although this variability was not significantly larger compared to smaller bearings. Finally, this research also investigated how the shear modulus of the elastomer changes as the temperature decreases. Results of tests showed that the shear modulus increases significantly as temperature decreases. This effect can be significant when analyzing the behavior of bridge bearings under temperature variations.
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: National Cooperative Highway Research Program Publisher: Transportation Research Board ISBN: 0309099188 Category : Bridges Languages : en Pages : 65
Book Description
At head of title: National Cooperative Highway Research Program.
Author: Shuenn-Yih Chang Publisher: CRC Press ISBN: 0415643422 Category : Technology & Engineering Languages : en Pages : 976
Book Description
Advances in Civil Engineering and Building Materials presents the state-of-the-art development in: - Structural Engineering - Road & Bridge Engineering - Geotechnical Engineering - Architecture & Urban Planning - Transportation Engineering - Hydraulic Engineering - Engineering Management - Computational Mechanics - Construction Technology - Building Materials - Environmental Engineering - Computer Simulation - CAD/CAE Emphasis was given to basic methodologies, scientific development and engineering applications. Advances in Civil Engineering and Building Materials will be useful to professionals, academics, and Ph.D. students interested in the above mentioned areas.
Author: Bridger D. Morrison
Author: Cong Sun (Ph. D.)
Author: M. Shahria Alam
Author: 
Author: Charles W. Roeder
Author: James M. Kelly
Author: 
Author: National Cooperative Highway Research Program
Author: 
Author: Shuenn-Yih Chang