Design of Steel I-Beams: A Proposed Equation

Design of laterally unsupported steel I-section beams according to Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD) techniques involves usage of multiple equations. According to most codes of practice, three distinct zones are established for the behaviour of laterally unsupported steel beams. Each of these zones is defined by a different design equation. In this paper, a single equation which defines the moment resistance is suggested for the three zones defining the behaviour of laterally unsupported steel beams. Results of the proposed equations are compared to those obtained using the design provisions of the Egyptian, Canadian and American codes of practice (ECP-LRFD 2008, CAN/CSA S16-09 2009 and AISC 2010, respectively). The proposed equation is also verified against results obtained from nonlinear numerical analysis based on the finite element technique for steel I-beams.