Enhancing the Adequacy of Indian Standard Rolled Steel I Sections by Increasing the Width of Flange

The scientific background behind the dimensioning of Indian Standard rolled I-sections available in IS 808 1989 may have been based on the Working Stress Method (WSM) of the design of steel structures. Due to the recent developments in the design philosophies (i.e., Load and Resistance Factor Design (LRFD)) for the design of steel structures, it is important to establish the adequacy of Indian standard hot rolled steel sections. It is also necessary to assess the need to revise the dimensions of the rolled sections. The study presented in this paper evaluates the suitability of Indian standard hot-rolled steel I-sections as per the design guidelines given in the latest revision of the Indian Standard Code of Practice for General Construction in Steel (IS 800 2007). Laterally unsupported simple beams of spans 3 m, 6 m, 9 m, and 12 m that are subjected to uniformly distributed load over the entire span are examined in this study. The maximum bending moment and Elastic section modulus of Indian Standard Wide Beams (ISWB) after an increase in the width of the flange (if necessary) are grouped and plotted with the help of a C program developed by the authors. The results show that the variation of bending moment with section modulus is parabolic. Also, the rate of increase in load-carrying capacity with respect to section modulus decreases with an increase in the span. However, the increase in the width of the flange results in a lower rate of decrease comparatively.