Flexural-Torsional Stability Design of Hotrolled Nonslender Unequal Leg Angles Subjected to Axial Compression

J. V. Sai Babu *, K. S. Vivek **
*-** Department of Civil Engineering, Vasireddy Venkatadri Institute of Technology, Guntur, Andhra Pradesh, India.
Periodicity:December - February'2021
DOI : https://doi.org/10.26634/jste.9.4.17678

Abstract

Unequal leg angles may be provided in transmission line towers or trusses and hence are subjected to axial compression either in direct or reversal stress states. In axial compression, steel Unequal leg angles are prone to flexural-torsional instability. European and American codes of practices include design provisions to check for flexural-torsional buckling of angle sections under axial compression but the Indian code of practice recommends flexural stability design only. In this simple study, initially a linear buckling analysis of non-slender unequal leg single angles specified is carried out to find the primary mode of buckling. It is observed that flexural-torsional buckling is the primary mode for all the sections considered in the study. Later, the design compressive strengths corresponding to flexural buckling (FB) are presented. Based on the available literature, a simple modification is suggested to determine the design compressive strengths corresponding to the governing flexural-torsional buckling (FTB) mode. It is observed that the design strength due to flexural-torsional buckling, Pd, FTB is always lesser than the design strength due to flexural buckling. The difference is more pronounced in case of sections of intermediate non-dimensional slenderness ratio and greater d/b ratio. Design curves for the considered cases are also provided. A simple equation is proposed in terms of plate slenderness ratio (d/t), (b+d)/t, leg width ratio (d/b) and non-dimensional flexural slenderness ratio (FB). From the study, it is concluded that there is a need for incorporation of a clause exclusively on flexural-torsional stability design of non-slender unequal leg angles subjected to axial compression in future.

Keywords

Axial Compression, Flexural Buckling, Flexural–Torsional Buckling, Non-Slender Steel, Unequal Leg Angle

How to Cite this Article?

Babu, J. V. S., and Vivek, K. S. (2021). Flexural-Torsional Stability Design of Hotrolled Nonslender Unequal Leg Angles Subjected to Axial Compression. i-manager's Journal on Structural Engineering, 9(4), 15-30. https://doi.org/10.26634/jste.9.4.17678

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