Secondary Prestressing Moments in Rehabilitated Posttensioned Bridges
Publication: Journal of Bridge Engineering
Volume 10, Issue 2
Abstract
Typical rehabilitation procedures for posttensioned slab bridges involve removing concrete from the top surface of the bridge, replacing corroded reinforcement, and resurfacing with new concrete. These permanently change primary and thus secondary prestressing moments. Continuous posttensioned bridges often rely on secondary prestressing moments to counteract dead and live load moments over interior supports and thus changes caused by rehabilitation impact serviceability and, particularly, ultimate limit states. An analysis procedure is derived for computing the changes in prestressing moments caused by rehabilitation. The impact of rehabilitation on a two-span continuous voided-slab bridge is evaluated considering rehabilitation schemes where both spans are rehabilitated simultaneously, or where one span is completely rehabilitated before work commences on the other. Rehabilitation creates concentrated primary prestressing moments at the exterior supports and at interfaces between solid and voided regions that reduce or even reverse the secondary moment at the interior support. The two-span scheme virtually eliminates secondary prestressing moments and, contrary to intuition, the span-by-span scheme has a markedly greater impact.
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Acknowledgments
Financial support from the Natural Sciences and Engineering Research Council of Canada in the form of a Postgraduate Scholarship to the first writer and a Discovery Grant to the second writer are gratefully acknowledged. The writers also thank Dr. R. Green, University of Waterloo, for providing several references and insight throughout the investigation, and Mr. A. Turnbull, P. Eng., of the Ontario Ministry of Transportation, for providing drawings for a suitable case bridge.
References
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 10 • Issue 2 • March 2005
Pages: 215 - 227
Copyright
© 2005 ASCE.
History
Received: Jul 15, 2003
Accepted: Dec 29, 2003
Published online: Mar 1, 2005
Published in print: Mar 2005
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