Download or read book Elastomeric Bearings in High Demand Applications written by Liwei Han and published by . This book was released on 2016 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pot and disk bearings are typically used in high-demand bridge applications where significant demands are imposed on bearings at the supports to accommodate rotations and complex bridge movements from both environmental thermal loads and vehicular traffic. However, past bridge research, design, and installation experience demonstrates that less costly elastomeric bearings are not only easy to install, inspect, and replace, but also more forgiving of installation errors. The use of elastomeric bearings in high-demand applications results in much less structural restraint against bridge thermal deformation than other more sophisticated sliding bearings. Although past bridge design practice includes applications of elastomeric bearings in two steel trapezoidal box girder systems in Central Texas, the use of elastomeric bearings in high-demand application is nevertheless largely impeded by historical and current bearing design provisions at national and state levels that are unduly restrictive for large-sized elastomeric bearings as well as the scantiness of field, laboratory, and numerical investigations on them. This investigation reported in this dissertation is part of a research project including material study, full-scale testing, field monitoring, and finite-element studies, with a focus primarily on finite-element studies of elastomeric bearings in comparison with laboratory and field measurements. A three-dimensional finite-element model capable of simulating the behavior of elastomeric bearings in full-scale compression, shear, and rotation testing was first developed and validated by experimental results from the full-scale testing. More comprehensive parametric finite-element studies of elastomeric layers under axial load and rotational deformation were then carried out leading to the development of a reliable elastomeric bearing design with improved economy and serviceability, based on total shear strain approach. A three-dimensional finite-element study of a continuous curved steel trapezoidal box girder system (IH-35 NB & US-290 EB direct connector) was carried out to investigate the translational movements and rotations imposed on elastomeric bearings under thermal loads with 100-year return period, and validated by instrumentation measurements from field monitoring. Design suggestions were put forward with regard to determining demands on elastomeric bearing s under thermal loads in high-demand applications. A field investigation was finally carried out on elastomeric bearings on the instrumented bridge, two of which were found to be damaged to different extents. The results reveal that the two damaged bearings are subjected to excessive amount of transverse rotation. Further analyses by calculating the maximum shear strain of all bearings using the proposed design approach confirmed that the observed bearing damage is the direct result of the excessive transverse angle of inclination on the concrete bearing seat surface.
Download or read book 0 6785 Extending Use of Elastomeric Bearings to Higher demand Applications written by Todd Aaron Helwig and published by . This book was released on 2015 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Expanding the Use of Elastomeric Bearings for Higher Demand Applications written by Konstantinos Victor Belivanis and published by . This book was released on 2017 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Elastomeric bearings have been widely used in short-span bridge systems as they provide a reliable and cost-effective means of accommodating translations compared to the pot bearing alternatives. However, in higher demand applications pot and disk bearings are commonly used to accommodate significant forces and rotations and complex bridge movements from both thermal loads and daily truck traffic. Although elastomeric bearings have been designed for and utilized in twin steel trapezoidal box girder systems in Texas, classifying as higher demand applications, the lack of experimental and numerical research on such bearings, as well as some occasions of poor performance, dictate the need of further investigating their design requirements and performance. The research presented in this dissertation is part of a broader research project including material-level studies, field monitoring of bridge bearings, large-scale experimental testing, and finite element simulations. This dissertation focuses on the large-scale experimental testing and investigates the effect of several parameters on the compression and shear stiffness of elastomeric bearings. Specifically, bearing tests demonstrated the poor prediction ability current AASHTO axial stiffness prediction equations as well as a shear stiffness dependence on the level of axial load and, in some cases, on the shearing direction of the bearing. However, it was shown that both AASHTO Method A and B produce safe elastomeric bearing designs. The finite element studies demonstrated that shim misalignment and cover friction can cause a reduction in the axial stiffness of an elastomeric bearing. In addition, an extensive finite element parametric study was performed to show variations in elastomeric bearings shear stiffness with different axial loads and shearing directions with a wide range of aspect ratios and height to width ratios.
Download or read book Extending Use of Steel laminated Elastomeric Bearings to Higher Demand Applications written by Konstantinos Victor Belivanis and published by . This book was released on 2015 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Material Study of the Steel Reinforced Elastomeric Bridge Bearings written by Cong Sun (Ph. D.) and published by . This book was released on 2015 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Rotation Limits for Elastomeric Bearings written by National Cooperative Highway Research Program and published by Transportation Research Board. This book was released on 2008 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: At head of title: National Cooperative Highway Research Program.
Download or read book Stability of Elastomeric Bearings for Seismic Applications written by Jose Sanchez and published by . This book was released on 2011 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Elastomeric seismic isolation bearings have been shown to effectively mitigate structural and nonstructural damage during earthquakes. During strong shaking, elastomeric bearings need to carry high axial loads while being subjected to large lateral deformations. An appropriate evaluation of the critical load for moderate as well as for large displacement (shear strain above 100%) is essential to avoid an undesirable failure of the isolation device at high axial loads. This study presents results from an on-going experimental program to examine the performance limit states in seismically isolated buildings. The specific objective is to compare two different experimental procedures to evaluate the critical load of an elastomeric bearing and compare them to analytical prediction. The first procedure to evaluate the bearing critical load followed a previously used experimental method were the elastomeric bearing is held to a specified horizontal displacement while applying increasing axial load until the critical load is achieved. The second procedure proposed here first applies a constant axial load followed by a lateral displacement until reaching the stability limit of the bearings. The second procedure proposed in this thesis showed to be an accurate and direct approach to obtain the critical load directly from the stability test data and considerably minimizes the data analysis required as in the first procedure. The reduced area formulation commonly used to predict the critical load of the elastomeric bearings is compared to the experimental results. Here, it is recommended to use the effective shear modulus at small shear strains in order to get better agreement with experimental results. In addition, the shear strain and pressure distribution is computed analytically to examine the state of the bearing material at the instability point.
Download or read book High load Multi rotational Bridge Bearings written by John F. Stanton and published by Transportation Research Board. This book was released on 1999 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanics of Rubber Bearings for Seismic and Vibration Isolation written by James M. Kelly and published by John Wiley & Sons. This book was released on 2011-08-24 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Analysis of Elastomeric Bridge Bearings written by O. Hamzeh and published by . This book was released on 1995 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: A two-dimensional nonlinear p-version finite element method is developed for the analysis of boundary value problems relevant to elastomeric bridge bearings. The method incorporates polynomial shape functions of the hierarchic type for the modeling of large-deformations rubber elasticity. In addition, a frictional-contact algorithm based on a penalty formulation and suitable for the interaction of the pad with rigid flat surfaces is derived and implemented. The J sub 2 flow theory with isotropic hardening is utilized to model the reinforcing steel as a bilinear elastoplastic material. Examples are presented to illustrate the performance of the element and some guidelines for the selection of appropriate orders of interpolation and integration rules. The results of a study performed to examine the effects of several design parameters of the bearing are presented. Comparisons with experimental findings are shown. A dynamic lumped model for the walking of the bearing is developed. Viscous frictional interfaces with the girder and the abutment are included. Several cases are analyzed to investigate the factors that affect this phenomenon.
Download or read book Bulletin written by United States. Bureau of Mines and published by . This book was released on 1976 with total page 1272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recent Advances and Applications of Thermoset Resins written by Debdatta Ratna and published by Elsevier. This book was released on 2022-02-19 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent Advances and Applications of Thermoset Resins, Second Edition provides a reference source for anyone interested in understanding the chemistry, processing, properties, composites and applications of thermoset resins. Sections cover the chemistry of thermoset resins and recent advances in various aspects, including toughening, micro-reinforcement, nano-reinforcement, simultaneous nano-reinforcement and toughening. The book provides detailed information on synthesis, characterization and processing techniques. A critical review of the latest advances in thermoset-based composites and nanocomposites is also presented, along with future directions of research in various areas of thermoset resins. This is a valuable resource for researchers, scientists and advanced students in polymer science, plastics engineering, adhesives and coatings, composites, and materials engineering, as well as R&D professionals, engineers and manufacturers with an interest in thermoset resins and materials for advanced applications. Offers comprehensive information on the chemistry, processing, properties and applications of thermoset resins Presents and reviews cutting-edge developments in the field, including sections on composites, nanocomposites, bio-based resins and 3D printing Includes the latest methods for analysis, characterization, testing and evaluation of thermoset materials
Download or read book Proceedings of the Canadian Society of Civil Engineering Annual Conference 2022 written by Rishi Gupta and published by Springer Nature. This book was released on 2023-08-05 with total page 1180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprises the proceedings of the Annual Conference of the Canadian Society of Civil Engineering 2022. The contents of this volume focus on specialty conferences in construction, environmental, hydrotechnical, materials, structures, transportation engineering, etc. This volume will prove a valuable resource for those in academia and industry.
Download or read book European Seismic Design Practice Research and Application written by A.S. Elnashai and published by Routledge. This book was released on 2022-03-23 with total page 683 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is evident that European earthquake engineering research and design practice is assuming a role of increasing importance on the international scene. This is primarily due to two considerations; firstly the emergence of a core of European earthquake engineers who are co-operating on a long-term basis for the development of seismic design criteria specific to the European environment and secondly the identification of new problems in existing design practice in the USA and in Japan. It is in this context that European earthquake engineering activities and publications are eagerly observed and awaited by the international community. Includes a compact set of papers from leading research institutions, laboratories and companies in Europe, with a healthy number of contributions from elsewhere. It represents the European state-of-the-art and practice in earthquake testing, analysis & design of civil engineering works as well as strong-motion & hazard studies.
Download or read book Mineral Facts and Problems written by United States. Bureau of Mines and published by . This book was released on 1975 with total page 1266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exhibits written by United States. Congress. Senate. Select Committee on Ethics and published by . This book was released on 1981 with total page 1064 pages. Available in PDF, EPUB and Kindle. Book excerpt:
