Girder Load Distribution for Seismic Design of Integral Bridges
Publication: Journal of Bridge Engineering
Volume 20, Issue 1
Abstract
Current seismic design practice related to integral bridge girder-to-cap beam connections allows little or no lateral seismic load to be distributed beyond the girders immediately adjacent to the column. However, distribution results from several large-scale tests have shown that the distribution of column seismic moment typically engages all the girders. An approach utilizing simple stiffness models to predict distribution in integral bridge structures is presented in detail; distribution predictions based on grillage analyses also are compared. The experimental results and the analytical results from the stiffness and grillage models show that current design methods related to vertical load distribution are sufficiently accurate. However, when applied to the distribution of lateral load, similarly obtained results reveal that current design practice does not appropriately account for the amount of load that is distributed beyond the girders adjacent to the column to the nonadjacent girders. The current practice leads to excessive girder-to-cap connection reinforcement, increased girder depth, unnecessarily high seismic mass, and increased construction cost. Finally, this paper makes recommendations for more appropriate distribution of seismic lateral load in integral bridge superstructures.
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Acknowledgments
The large-scale tests that provided the data for this paper were made possible through funding from CALTRANS for the PBT and ITB units and the NCHRP for the SPC units. The authors thank Jay Holombo of T. Y. Lin International Group, Robert Abendroth of Iowa State University (ISU), and Ryan Staudt (former graduate student of ISU) for their contributions to this study.
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 20 • Issue 1 • January 2015
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Nov 5, 2013
Accepted: Apr 11, 2014
Published online: May 6, 2014
Published in print: Jan 1, 2015
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