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The eigenvalues of isolated bridges with transverse restrains at the end abutments

The eigenvalues of isolated bridges with transverse restrains at the end abutments

Makris, Nicos, Kampas, Georgios and Angelopoulou, Dimitra (2009) The eigenvalues of isolated bridges with transverse restrains at the end abutments. Earthquake Engineering and Structural Dynamics, 39 (8). pp. 869-886. ISSN 0098-8847 (Print), 1096-9845 (Online) (doi:https://doi.org/10.1002/eqe.971)

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Abstract

This paper examines the eigenvalues of multi-span seismically isolated bridges in which the transverse displacement of the deck at the end-abutments is restricted. With this constraint the deck is fully isolated along the longitudinal direction, while along the transverse direction the deck is a simple supported beam at the end abutments which enjoys concentrated restoring forces from the isolation bearings at the center piers. For moderate long bridges the first natural period of the bridge is the first longitudinal period, while the first transverse period is the second period, given that the flexural rigidity of the deck along the transverse direction shortens the isolation period offered by the bearings in that direction. This paper shows that for isolated bridges longer than a certain critical length, the first transverse period becomes longer than the first longitudinal period despite the presence of the flexural rigidity of the deck. This critical length depends on whether the bridge is isolated on elastomeric bearings or on spherical sliding bearings. This result is also predicted with established commercially available numerical codes only when several additional nodes are added along the beam elements which are modeling the deck in-between the bridge piers. On the other hand this result can not be captured with the limiting idealization of a beam on continuous distributed springs (beam on Wrinkler foundation) –a finding that has practical significance in design and system identification studies. Finally, the paper shows that the normalized transverse eigenperiods of any finite-span deck are self-similar solutions that can be represented by a single master curve and are independent of the longitudinal isolation period or on whether the deck is supported on elastomeric or spherical sliding bearings.

Item Type: Article
Uncontrolled Keywords: seismic isolation; bridge; eigenvalues; system identification; self-similarity; dynamic response
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Faculty / Department / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > Centre for Innovative & Smart Infrastructure
Faculty of Engineering & Science > Department of Engineering Science
Last Modified: 28 Mar 2018 09:25
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
Selected for GREAT 2019: None
URI: http://gala.gre.ac.uk/id/eprint/19469

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