Performance improvement of seismic-isolated bridges near active faults using elastic-gap devices

Date

2017-04-27

Author

Dicleli, Murat

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For seismic isolated bridges (SIBs) subjected to near-fault (NF) ground motions with directivity effect, the isolator displacements tend to be considerably large. Consequently, isolators with very large dimensions may be required for SIBs located in NF zones. This may lead to very large expansion joints and very large seat widths as well. In this research, the efficiency of providing supplemental elastic-gap devices to improve the performance of seismic-isolated bridges (SIBs) in near-fault (NF) zones is investigated. The device is primarily made of elastomeric bearings placed in parallel with seismic isolators to provide additional elastic stiffness upon closure of a gap. A parametric study, involving more than 400 nonlinear time history (nonlinear time-history) analyses of realistic and simplified structural models of typical SIBs are conducted using simulated and actual NF ground motions to investigate the applicability of the proposed solution. It is found that providing elastic-gap device is beneficial in reducing the isolator displacements to manageable ranges. It is also found that the gap and the stiffness of the elastic-gap device may be chosen in relation to the magnitude of the NF ground motion to minimize the isolator displacements by moving away from the high-energy region of the spectrum. Further analyses conducted using a realistic structural model of an existing bridge and five NF earthquakes with moderate to large magnitudes confirmed that elasticgap device may be used to reduce the displacement of the isolators while keeping the substructure base shear forces at practically acceptable ranges for SIBs located in NF zones.

URI

https://hdl.handle.net/11511/71967
http://db.nzsee.org.nz/2017/O4C.7_Dicleli.pdf

Conference Name

NZSEE Annual Technical Conference and 15th World Conference on Seismic Isolation, Energy Dissipation and Active Vibration Control of Structures (27 Nisan 2017)

Collections

Department of Engineering Sciences, Conference / Seminar

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Citation Formats

M. Dicleli, “Performance improvement of seismic-isolated bridges near active faults using elastic-gap devices,” Wellington, Yeni Zelanda, 2017, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/71967.