Journal of Constructional Steel Research 51 (1999) 1–19 Bracing requirements of inelastic columns Heungbae Gil a,* , Joseph A. Yura b a Highway Research Center, Korea Highway Corporation, Sungnam-shi, Kyungki-do, South Korea b Department of Civil Engineering, The University of Texas at Austin, Austin, TX, USA Received 17 August 1998; received in revised form 11 January 1999; accepted 21 January 1999 Abstract Various types of braces are used to prevent buckling of structures and increase buckling strength. While bracing requirements of elastic structures are well explained, those of inelastic structures are not fully developed. Experimental and analytical studies were conducted to deter- mine bracing requirements of inelastic columns. In the experimental study, columns with a brace at mid height were loaded to their maximum limit with the brace stiffness at the mid height as the main variable. The tangent modulus of the columns which governs the inelastic buckling loads was kept constant. An analytical study was also performed to compare with the experimental results. The columns were modeled and analyzed by the finite element program, ABAQUS. It was found through the experimental and analytical studies that the bracing requirements for inelastic columns depend on the number of braces, the buckling load, and the length of a column but not on the material state. The results show that Winter’s simplified method to determine full brace requirements can be applied to inelastic members as well as elastic members.  1999 Published by Elsevier Science Ltd. All rights reserved. Keywords: Column; Inelastic buckling; Brace; Bracing; Column brace Nomenclature  deflection at the center of the column E Young’s modulus of elasticity E T' tangent modulus of the gross section I CORE moment of inertia of the core high strength steel bar I GROSS moment of inertia of the gross column section * Corresponding author. E-mail: heungbae@netsgo.com 0143-974X/99/$ - see front matter  1999 Published by Elsevier Science Ltd. All rights reserved. PII:S0143-974X(99)00002-4