Modeling the local buckling failure of angle sections with beam elements

Abstract

Slender steel sections are widely used in the construction of steel structures such as lattice structures for transmission li ne and telecommunication towers. Local buckling may be the observed failure mode under compression loads for these slender sections, and many experimental studies have been conducted to evaluate their resistance. All steel design codes include equations to account for local buckling. In numerical models, local buckling can be reproduced using 2D shell or 3D elements. Nonlinear numerical models have been developed in the last decades that can capture the complex behavior of lattice structures up to failure. These models typically use beam elements that consider correctly the global buckling and yielding of sections but do not consider the local buckling of angles due to geometrical limitations. This article proposes a method that modifies the material behavior of sections to involve the local buckling failure in the analysis. Forty-two experimental tests were conducted on short angles and a general stress-strain formula was defined based on the test results. The formula relates the local buckling slenderness ratio of the members to a material constitutive law that accounts for the local buckling. To evaluate the method, the numerical results were compared to those of four x-braced frame configurations using slender angle sections. The results demonstrate that the proposed method can accurately model the local buckling failure of fiber beam elements.