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Stability Assessments of Unbonded Fiber Reinforced Elastomeric Isolators
Fiber Reinforced Elastomeric Isolators (FREIs) have been proposed as a low-cost alternative to Steel Reinforced Elastomeric Isolators (SREIs), replacing the reinforcing steel plates with fiber fabrics. Despite having a similar elastic stiffness, fibers are cheaper and lighter than steel, and a simpler and faster manufacturing process, such as cold-vulcanization, can be used for FREIs instead of expensive hot-vulcanization process used for SREIs. When FREIs are unbonded to the top and bottom substructure, the bearings exhibit softening under imposed lateral deformations with or without instability. The stable/unstable response of the bearing depends on its mechanical and geometric parameters, and mostly on the secondary shape factor. Rather high secondary shape factor values ensure a stable response of the bearing, while below a limit threshold the response would be unstable, also depending on the shear modulus of the rubber and the vertical applied pressure. This thesis studies the stability of fiber reinforced elastomeric isolators under simultaneous axial and both mono and bi-directional shear loads. Three types of FREIs are considered, namely i) infinite long strip-shaped, ii) rectangular-shaped and iii) square-shaped FREIs, through analytical, numerical and experimental approaches. As a matter of fact, analytical equations involving the main parameters affecting the vertical response and the lateral stability are introduced. Easy-to-use design stability charts are provided and a simple strategy to improve the stability range of the different-shaped FREIs under combined vertical and horizontal loads are also shown. Conclusions of this study could help disseminate knowledge on the use of FREIs for seismic base isolation of structures in both developed and developing countries.
Stability Assessments of Unbonded Fiber Reinforced Elastomeric Isolators
Fiber Reinforced Elastomeric Isolators (FREIs) have been proposed as a low-cost alternative to Steel Reinforced Elastomeric Isolators (SREIs), replacing the reinforcing steel plates with fiber fabrics. Despite having a similar elastic stiffness, fibers are cheaper and lighter than steel, and a simpler and faster manufacturing process, such as cold-vulcanization, can be used for FREIs instead of expensive hot-vulcanization process used for SREIs. When FREIs are unbonded to the top and bottom substructure, the bearings exhibit softening under imposed lateral deformations with or without instability. The stable/unstable response of the bearing depends on its mechanical and geometric parameters, and mostly on the secondary shape factor. Rather high secondary shape factor values ensure a stable response of the bearing, while below a limit threshold the response would be unstable, also depending on the shear modulus of the rubber and the vertical applied pressure. This thesis studies the stability of fiber reinforced elastomeric isolators under simultaneous axial and both mono and bi-directional shear loads. Three types of FREIs are considered, namely i) infinite long strip-shaped, ii) rectangular-shaped and iii) square-shaped FREIs, through analytical, numerical and experimental approaches. As a matter of fact, analytical equations involving the main parameters affecting the vertical response and the lateral stability are introduced. Easy-to-use design stability charts are provided and a simple strategy to improve the stability range of the different-shaped FREIs under combined vertical and horizontal loads are also shown. Conclusions of this study could help disseminate knowledge on the use of FREIs for seismic base isolation of structures in both developed and developing countries.
Stability Assessments of Unbonded Fiber Reinforced Elastomeric Isolators
Galano, Simone (Autor:in)
03.02.2022
Galano, Simone (2022) Stability Assessments of Unbonded Fiber Reinforced Elastomeric Isolators. [Tesi di dottorato]
Hochschulschrift
Elektronische Ressource
Italienisch , Englisch
DDC:
624
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