Higher Level Evaluation of a Reinforced Concrete Slab Bridge
Publication: Journal of Bridge Engineering
Volume 15, Issue 2
Abstract
In New Mexico, many reinforced concrete slab (RCS) bridges provide service on interstates I-10, I-25, and I-40. The load rating for this type of bridge largely depends on the live-load moment in the slab. Consequently, the objective of this study was to determine a more accurate value for the equivalent strip width using higher level evaluation techniques. A continuous RCS bridge was evaluated starting with an AASHTO load and resistance factor rating analysis. A diagnostic test was then conducted to measure live-load strains which showed that the slab stiffness fit within cracked and gross section behavior. Furthermore, slab moments from finite element analysis agreed reasonably well with experimental moments derived using the average of the cracked and gross section modulus. From refined analysis, the equivalent strip widths for positive moment were 26.1 and 22.1% greater than those calculated by the AASHTO approximate method for the exterior and interior spans, respectively. The refined widths for negative moment were greater than AASHTO by 13.1 and 11.1%. This increase in the equivalent strip width reduced the live-load effects, which proportionally increased the rating factors.
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Acknowledgments
The writers thank the NMDOT Research Bureau for providing financial support to conduct this research project. The NMSU research team would also like to acknowledge the advice and review provided by Mr. Jimmy Camp (State Bridge Engineer, NMDOT), Dr. Steve Maberry (Bridge Rating Engineer, NMDOT), Mr. Jeff Vigil (Bridge Management Engineer, NMDOT), and Mr. Wil Dooley (Division Bridge Engineer, FHWA). The management provided by Mr. Rais Rizvi (Research Engineer, NMDOT) and Mr. Virgil Valdez (Research Analyst, NMDOT) is also greatly appreciated. Last, the writers thank Mr. Earl Franks (Bridge Engineer, NMDOT) and the bridge crew from NMDOT District I for their assistance in the field testing.
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 15 • Issue 2 • March 2010
Pages: 172 - 182
Copyright
© 2010 ASCE.
History
Received: Aug 11, 2008
Accepted: Mar 31, 2009
Published online: May 15, 2009
Published in print: Mar 2010
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