Revisited Live Load for Simple-Span Bridges
Publication: Journal of Bridge Engineering
Volume 26, Issue 1
Abstract
Twenty-five years ago, a bridge live-load model was developed along with the calibration of the AASHTO LRFD Specifications. The statistical parameters of truck loads were based on the Ontario, Canada, truck survey performed in the 1970s. The objective of this paper is to review the available weigh-in-motion (WIM) data and update the live-load model accordingly. The considered WIM database includes over 200 million records, from 44 WIM locations around the USA, with about 1–2 million vehicles per year for each location. The actual number of records depends on traffic volume expressed in terms of an average annual daily truck traffic (AADTT) and local conditions, such as type of road, local facilities, seasonal factors. The cumulative distribution functions of load effect are extrapolated to predict the maximum expected live load for extended time periods. The statistical parameters of live load are determined for the static component of the live-load effect for one lane in simple-span bridges based on the actual WIM data. The analysis showed that there is a 15%–20% increase in live load in comparison to Ontario data. An updated design tandem is proposed to adequately represent the traffic load for short simply supported spans.
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Acknowledgments
The present study benefited from the previous research undertaken as part of the SHRP2 R19B and NCHRP 12-83, in particular work done by former doctoral students at the University of Nebraska Drs. Przemyslaw Rakoczy, Marek Kozikowski, and Marta Lutomirska. The authors are grateful for discussions with Drs. John M. Kulicki, (late) Dennis Mertz, Wagdy Wassef, Tom Murphy, and Hani Nassif.
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Information
Published In
Journal of Bridge Engineering
Volume 26 • Issue 1 • January 2021
Copyright
© 2020 American Society of Civil Engineers.
History
Received: Mar 9, 2020
Accepted: Jul 23, 2020
Published online: Nov 12, 2020
Published in print: Jan 1, 2021
Discussion open until: Apr 12, 2021
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