A Study on Application of Elastic Theory for Computing Flexural Stresses in Preflex Beam

Authors: Nasiri Ahmadullah, Shimozato Tetsuhiro, Masayuki Tai

Abstract:

This paper presents the step-by-step procedure for using Elastic Theory to calculate the internal stresses in composite bridge girders prestressed by the Preflexing Technology, called Prebeam in Japan and Preflex beam worldwide. Elastic Theory approaches preflex beams the same way as it does the conventional composite girders. Since preflex beam undergoes different stages of construction, calculations are made using different sectional and material properties. Stresses are calculated in every stage using the properties of the specific section. Stress accumulation gives the available stress in a section of interest. Concrete presence in the section implies prestress loss due to creep and shrinkage, however; more work is required to be done in this field. In addition to the graphical presentation of this application, this paper further discusses important notes of graphical comparison between the results of an experimental-only research carried out on a preflex beam, with the results of simulation based on the elastic theory approach, for an identical beam using Finite Element Modeling (FEM) by the author.

Keywords: Composite girder, elastic theory, preflex beam, prestressing.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1132351

References:

[1] Frank A. Mink, Jr, “An Experimental Investigation of Preflex method of prestressed concrete”, Georgia Institute of Technology, May 1955, Ch.2, 3, 5 and 7.
[2] D. W. Haines, C. P. Pitts, S. J. Errera, “Tests of Preflexed beams”, Fritz Engineering Laboratory Report No.282.1, September 1961.
[3] PAP, Zsuzsa Borbala, “PREFLEX girders: Prefabricated composite bridges”, Bauhaus Summer School in Forecast Engineering, Weimar, Germany, 17-29 August 2014.
[4] S. Staquet, F. Toutlemonde, “Test up to ultimate limit state and failure of innovative prebended steel-VHPC beams for railway bridges in France”.
[5] Kebo Zhang, Suping Li, Kaisheng Liu. “Experimental Study on Static and Fatigue Behaviour of Steel-Concrete Preflex Prestressed Composite Beam”.