Lateral Stability of a Prestressed Concrete Girder


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Title: Lateral Stability of a Prestressed Concrete Girder

Author(s): Walter Podolny, Jr. and John B. Scalzi

Publication: Journal Proceedings

Volume: 58

Issue: 9

Appears on pages(s): 317-326

Keywords: none

Date: 9/1/1961

The object of this research was to apply theoretical lateral buckling relationships to a prestressed concrete girder determine the validity of the theory and the limitations of the assumptions. Based on theoretically established proportions, a test girder was constructed 43 ft 6 in. long, with an inverted T cross section. The girder was loaded uniformly along the bottom flange, leaving the top compression flange unsup-ported for its entire length. Lateral buckling was found to be of little or no consequence in this test where, in accordante with present code restrictions, at least three lateral braces would have been necessary. Several theories indicated that the ultimate capacity of the concrete would be approached or exceeded before lateral buckling would occur. The various theories predicting the elastic lateral buck- ling of the beam based on varying degrees of restraint of the bottom flange indicate that the roof deck does provide restraint to the tension flange. A complete evaluation is difficult to make when based on the behavior of only one beam test. However, the test indicates that it is conservative to assume the beam to behave as a flat plate unrestrained along the tension flange. As a further conclusion the test indicates that perhaps the current lateral buckling restrictions of the present codes should be re-examined to determine a more realistic requirement.