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Experimental investigation of unbonded ordinary steel reinforced elastomeric bearings as an isolation system in bridges

Maghsoudi Barmi, A ; Sharif University of Technology | 2021

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  1. Type of Document: Article
  2. DOI: 10.1016/j.istruc.2021.02.055
  3. Publisher: Elsevier Ltd , 2021
  4. Abstract:
  5. Reduction of large tensile stresses and cost-efficiency has made unbonded isolators an attractive option as an isolation system. Following this idea and the results obtained by various researchers, it is shown that unbonded steel-reinforced elastomeric bearings (SREBs), which are used and designed for non-seismic actions, have inherently acceptable characteristics in tolerating large shear deformations for a cost-effective isolation system and can provide improved structural performance. However, this capacity is neglected in the design process. The current article presents an experimental program to analyze the mechanical properties of steel-reinforced natural rubber bearings without the upper and lower endplates when subjected to large shear displacements and to assess how they can be used and what are the limitations. The overall behavior of the bearing is explained and the affecting variables including the level of axial load, rate of loading, and contact conditions are discussed. A full-scale test setup using a pair of bearings sandwiched between three concrete platens is utilized which considers the interaction of compressive and cyclic shear loading. Even though it is costly and difficult, this setup provides a realistic approach for testing bearings while they are in contact with concrete on both sides. The test results reveal that under different vertical loading levels, all bearings exhibited stable hysteretic response. In presence of adequate axial load, the specimens were capable of tolerating shear strains more than 125% without slippage of the bearings. It was shown that albeit demonstrating low damping characteristics, these bearings provide adequate flexibility and shear displacement capacity which indicates they can be a proper choice for substitution as costly isolators in low to moderate seismic zones or for low-risk short span bridges in developing countries. © 2021 Institution of Structural Engineers
  6. Keywords:
  7. Elastomeric bearing ; Frictional behavior ; Bridge seismic isolation ; Unbonded
  8. Source: Structures ; Volume 32 , 2021 , Pages 604-616 ; 23520124 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S2352012421001661