Design of columns and struts in structural steel

Columns and struts carry load primarily in compression along their length, and are found in most building structures.

Columns constructed in traditional materials such as stone and brick tend to be of large cross-sectional size relative to their length.

The restraint at the ends of a column has a significant influence on the effective length and therefore the buckling strength.

Multi-storey columns are generally restrained at every floor level, and the effective length is therefore based on storey height.

Special consideration may need to be given to the effective length of columns in single storey buildings to account for practical construction details.

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.

Column buckling was first investigated by Euler who established that the buckling strength is inversely proportional to the square of the slenderness ratio.

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.

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

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