Live Load Distribution Factors for Moment in NEXT Beam Bridges
Publication: Journal of Bridge Engineering
Volume 23, Issue 3
Abstract
In recent years, northeast extreme tee (NEXT) beam bridges have gained increased attention in the bridge industry for their ease of construction. When designing a NEXT beam bridge, the actual live load moment in a beam stem can exceed the design stem moment (i.e., half of the design beam moment) because of the uneven stem spacing. Current guidelines conservatively use the average stem spacing to compute the live load distribution factor (LLDFs) per lane for moment for each stem, which is doubled to calculate the LLDFs for the entire NEXT beam. In this regard, this study aimed to evaluate the applicability of the current LRFD method for LLDFs per lane for moment to the NEXT beam bridges by employing validated finite-element (FE) simulations. Parametric studies were carried out by both simplified and detailed FE modeling of various bridges with minimum- and maximum-width NEXT beams to compute the FE LLDFs. By using the beam spacing and the properties of an entire NEXT beam section, the LRFD LLDFs for NEXT beam bridges were computed as LRFD types i, k, and h sections. The results of FE and LRFD LLDFs were compared, and results showed that LRFD LLDFs governed the FE LLDFs by at least 12%. In addition, it was observed that the LRFD types i and k sections were more applicable for NEXT beam bridges compared with the LRFD type h section.
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References
AASHTO. (2014). AASHTO LRFD bridge design specifications, 7th Ed.,Washington, DC.
Abaqus [Computer software].SIMULIA,Providence, RI.
Bajhat, R., et al. (2014). “Evaluation of moment live load distribution of a NEXT F beam bridge through field load testing and FE modeling.” Proc., 2014 PCI Annual Convention an Exhibition and National Bridge Conf.,Precast/Prestressed Concrete Institute,Chicago.
Barker, R. M., and Puckett, J. A. (1997). Design of highway bridges based on AASHTO LRFD bridge design specifications,Wiley,Hoboken, NJ.
CSiBridge [Computer software].Computers and Structures,Berkeley, CA.
Culmo, M. P., and Seraderian, R. L. (2010). “Development of the northeast extreme tee (NEXT) beam for accelerated bridge construction.” PCI J.,55(3), 86–101.
Dicleli, M., and Erhan, S. (2009). “Live load distribution formulas for single-span prestressed concrete integral abutment bridge girders.” J. Bridge Eng., 472–486.
Eamon, C. D., and Nowak, A. S. (2002). “Effects of edge-stiffening elements and diaphragms on bridge resistance and load distribution.” J. Bridge Eng., 258–266.
Eom, J., and Nowak, A. S. (2001). “Live load distribution for steel girder bridges.” J. Bridge Eng., 489–497.
Gheitasi, A., and Harris, D. K. (2015). “Overload flexural distribution behavior of composite steel girder bridges.” J. Bridge Eng., 04014076.
Huang, J., and Davis, J. (2016). “Skew correction factor for bending moment in NEXT beam bridges.” Proc., 2016 PCI Convention and National Bridge Conf.,Precast/Prestressed Concrete Institute,Chicago.
Huang, J., and Strazar, C. (2014). “Evaluation of live load distribution factor for NEXT beam bridge.” Proc., 2014 PCI Annual Convention an Exhibition and National Bridge Conf.,Precast/Prestressed Concrete Institute,Chicago.
Huang, J., and Woehl, D. (2014). “Continuous prestressed concrete bridge: Loss of full continuity.” Proc., 7th Int. Conf. on Bridge Maintenance, Safety and Management,International Association for Bridge Maintenance and Safety,Shanghai, China.
Khaleghi, B., et al. (2012). “Accelerated bridge construction in Washington State: From research to practice.” PCI J.,57(4), 34–49.
Kim, Y. J., Tanovic, R., and Wight, R. G. (2010). “Load configuration and lateral distribution of NATO wheeled military trucks for steel I-girder bridges.” J. Bridge Eng., 740–748.
Mabsout, M. E., Tarhini, K. M., Frederick, G. R., and Kobrosly, M. (1997). “Influence of sidewalks and railings on wheel load distribution in steel girder bridges.” J. Bridge Eng., 88–96.
PCI (Precast/Prestressed Concrete Institute). (2012). Guidelines for northeast extreme tee beam (NEXT beam), PCINE-12-NEXT, 1st Ed.,PCI Northeast, Belmont, MA.
Tonias, D. E., and Zhao, J. (2007), Bridge engineering: Design, rehabilitation and maintenance of modern highway bridges, 2nd Ed.,McGraw-Hill,New York.
Yousif, Z., and Hindi, R. (2007). “AASHTO-LRFD live load distribution for beam-and-slab bridges: Limitations and applicability.” J. Bridge Eng., 765–773.
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Published In
Journal of Bridge Engineering
Volume 23 • Issue 3 • March 2018
Copyright
© 2017 American Society of Civil Engineers.
History
Received: Jan 19, 2017
Accepted: Sep 15, 2017
Published online: Dec 22, 2017
Published in print: Mar 1, 2018
Discussion open until: May 22, 2018
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