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http://hdl.handle.net/11375/20619
Title: | Fiber Reinforced Elastomeric Isolators for Bridge Applications |
Authors: | Al-Anany, Yasser |
Advisor: | Tait, Michael |
Department: | Civil Engineering |
Publication Date: | 2016 |
Abstract: | Bridge structures are considered a critical component in transportation systems. Bridges are divided into two main components, the superstructure and the substructure. Often the superstructure is integrated with the substructure. However, this type of integrated connection results in a direct transmission of straining actions developed within the superstructure to the substructure and vice versa. This consequently leads to a significant increase in the demand capacity of both elements. Examples of various actions that can develop in the superstructure include thermal expansion/contraction, pre-stress shortening/camber and creep. Deformation induced from ground motions during a seismic event is an example of an action that develops in the substructure. It has been proposed to isolate the superstructure and substructure by implementing bearings/isolators between these two components in order to reduce the transmission of straining actions. If the elements are used only to transfer the vertical loads as well as to accommodate the rotational and/or lateral deformations then it is referred as a bearing. However, if the bearings are also used for seismic isolation of the bridge then they are defined as isolators. Thus, isolators also act as bearings, but bearings may not be capable of acting as isolators. Elastomeric bearings/isolators are among the most common and widely used bearing type. Traditional elastomeric bearings are comprised of elastomer layers reinforced with steel plates/shims and are called Steel Reinforced Elastomeric Isolators (SREI). However, the application of these bearings has been limited to high-importance structures. This is due to the fact that SREI are characterized by their high cost and weight. These features result from labour intensive manufacturing costs and significant weight of the steel shims and end plates. As such, it has been proposed that a reduction in weight and cost could be achieved if the steel reinforcement was replaced with another type of material having comparable mechanical properties to steel, such as fiber fabric sheets. This relatively new type of isolator is called a Fiber Reinforced Elastomeric Isolators (FREI). FREI can be constructed without thick steel end plates and are placed, unfastened, between the superstructure and the substructure. In this case, the isolator is denoted as an unbonded-FREI (U-FREI). In addition to the expected reduction in weight and potential cost, U-FREI can be manufactured and cut to the desired shape and size from large sheets using a standard band saw. Furthermore, U-FREI are able to detach from the contact supports by rollover and lift-off under excessive deformations in the lateral and rotational direction, respectively. This is due to the unbonded boundary conditions and the negligible flexural rigidity of the fiber reinforcement. Research studies have revealed that U-FREI have desirable performance characteristics for building applications. This dissertation investigates the feasibility of extending the use of U-FREI to bridge applications. Experimental testing was carried out to study U-FREI behaviour under a wide range of bridge loading conditions in the vertical, rotational, and lateral directions. Numerical studies were also completed to assess the resulting stress and strain state within U-FREI. Finally, the seismic performance of a bridge, equipped with a U-FREI isolation system was evaluated via non-linear time history analysis using a large suite of earthquake motions. |
URI: | http://hdl.handle.net/11375/20619 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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AL-ANANY_YASSER_MOHAMMED_2016_PhD.pdf | 18.23 MB | Adobe PDF | View/Open |
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