Elastomeric Bearings In High Demand Applications
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Elastomeric Bearings In High Demand Applications
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Author : Liwei Han
language : en
Publisher:
Release Date : 2016
Elastomeric Bearings In High Demand Applications written by Liwei Han and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
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.
Expanding The Use Of Elastomeric Bearings For Higher Demand Applications
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Author : Konstantinos Victor Belivanis
language : en
Publisher:
Release Date : 2017
Expanding The Use Of Elastomeric Bearings For Higher Demand Applications written by Konstantinos Victor Belivanis and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
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.
Extending Use Of Steel Laminated Elastomeric Bearings To Higher Demand Applications
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Author : Konstantinos Victor Belivanis
language : en
Publisher:
Release Date : 2015
Extending Use Of Steel Laminated Elastomeric Bearings To Higher Demand Applications written by Konstantinos Victor Belivanis and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Bridges categories.
0 6785 Extending Use Of Elastomeric Bearings To Higher Demand Applications
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Author : Todd Aaron Helwig
language : en
Publisher:
Release Date : 2015
0 6785 Extending Use Of Elastomeric Bearings To Higher Demand Applications written by Todd Aaron Helwig and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Bridges categories.
Material Study Of The Steel Reinforced Elastomeric Bridge Bearings
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Author : Cong Sun (Ph. D.)
language : en
Publisher:
Release Date : 2015
Material Study Of The Steel Reinforced Elastomeric Bridge Bearings written by Cong Sun (Ph. D.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
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.
Stability Of Elastomeric Bearings For Seismic Applications
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Author : Jose Sanchez
language : en
Publisher:
Release Date : 2011
Stability Of Elastomeric Bearings For Seismic Applications written by Jose Sanchez and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
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.
Rotation Limits For Elastomeric Bearings
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Author : National Cooperative Highway Research Program
language : en
Publisher: Transportation Research Board
Release Date : 2008
Rotation Limits For Elastomeric Bearings written by National Cooperative Highway Research Program and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Bridges categories.
At head of title: National Cooperative Highway Research Program.
Elastomeric Bridge Bearings
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Author : J. A. Yura
language : en
Publisher:
Release Date : 2001
Elastomeric Bridge Bearings written by J. A. Yura and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Science categories.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1995
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Aeronautics categories.
High Load Multi Rotational Bridge Bearings
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Author : John F. Stanton
language : en
Publisher: Transportation Research Board
Release Date : 1999
High Load Multi Rotational Bridge Bearings written by John F. Stanton and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with Technology & Engineering categories.