Brannigan's Building Construction Exam for Fire Service 2025 – Complete Practice Test

The main failure mode for slender columns is buckling. This occurs when a column is subjected to axial loads that exceed its critical load capacity, causing it to deform laterally or sideways rather than failing directly under compressive forces. Slender columns are characterized by a high height-to-thickness ratio, which makes them more susceptible to this type of failure. When the load reaches a certain threshold, the column's material properties and geometry lead to instability, resulting in buckling instead of crushing, which typically affects short and stout columns.

In contrast, crushing involves the material failing under direct compression, which is more common in shorter columns that can support higher axial loads without lateral deformation. Shearing refers to failure due to shear forces acting parallel to the surface of the material, and is not specific to columns. Tensing, or tensile failure, occurs when a member is pulled apart, but slender columns are primarily subjected to compressive loads, making buckling the predominant concern in these scenarios.