Keywords: beam bracing, lateral bracing, stability requirements, compression flange, lateral-torsional buckling, finite element method, FEM, I-shaped beams, lateral deflection, cross-section twist, I-shaped girders, lateral braces, brace design
Strength and stability requirements of lateral bracing for compression flange in I-shaped beams
Lateral-torsional buckling is a limit state that can reduce the full benefit of beam capacity, especially for long elastic beams according to the big lateral deflection and cross-section twist of un-braced compression flange. Lateral-torsional buckling can be avoided by proper designed braces. These braces require not only adequate stiffness but sufficient strength as well. In this paper three dimensional, 3-D, finite element models, for I-shaped girders, are developed using a finite element programme and utilising it to investigate braces requirements and the geometrical parameters that may affect these requirements. These parameters are outstanding flange width-to-thickness ratio 'c
fl', web height-to-thickness ratio 'h
w', flange width-to-web height ratio 'b
w', multiple braces 'n' and un-supported length-to-beam span 'L
t'. Using the available finite element analysis results of the studied parameters, some design equations are proposed for the design of lateral braces of simply supported I-shaped beams subjected to any type of loading and restrained laterally by any number of braces.