Design of columns and struts in structural steel
Behaviour of structural members in compression
Columns constructed in traditional materials such as stone and brick tend to be of large cross-sectional size relative to their length.
Column end fixity and effective length
The restraint at the ends of a column has a significant influence on the effective length and therefore the buckling strength.
Columns in multi-storey buildings
Multi-storey columns are generally restrained at every floor level, and the effective length is therefore based on storey height.
Columns in single storey buildings
Special consideration may need to be given to the effective length of columns in single storey buildings to account for practical construction details.
Combined bending and direct compression
Columns are often subject to some bending in addition to compression. Two factors contribute towards the bending in a practical column; these are eccentricity of real beam connection details, and the effect of wind loading.
Simplified procedures can be used to estimate the required size of column section.
Euler collapse load
Column buckling was first investigated by Euler who established that the buckling strength is inversely proportional to the square of the slenderness ratio.
Columns and struts carry load primarily in compression along their length, and are found in most building structures.
Method of sizing columns according to BS 5950
For a given axial load, steel grade, column length and end conditions, the procedure for sizing a column section is based on trial and error, and can be described as a sequence of steps.
Radius of gyration, cross-sectional shape and buckling
The radius of gyration is a convenient parameter, providing a measure of the resistance of a cross-section to lateral buckling.
A summarised overview of the designs of columns and struts in structural steel