Experimental study on stability behavior of equal-leg angle steel columns

Abstract

This paper presents a comprehensive experimental investigation on the behavior of single equal-leg angle steel columns under compression. A total of 648 specimens adequately cover the most frequently used angles in transmission towers were tested using elaborately designed apparatus of three typical end constraints. The experimentally obtained bearing capacities were then compared with the predictions of four commonly used design codes to determine the quantitative discrepancy and assess the applicability of the codes. All four predictions for the concentrically loaded specimens were found to be universally conservative, but the predictions varied considerably for mixed and eccentric conditions. The design of latticed steel transmission structures (ASCE) provides more precise predictions for concentric and mixed conditions, while the technical code for the design of tower and pole structures of overhead transmission line (DL/T (type a curve)) provides more accurate predictions for eccentric conditions. The predictions of DL/T (type b curve) are excessively conservative. Based on the comparative assessment and the experiment data, in accordance with the basic form of ASCE expressions, this paper proposes modified calculation formulae for stability factors and effective length coefficients for eccentrically loaded angles using least-square fitting. The accuracy and applicability of these formulae were verified through comparison.