Structural response of a single‐storey hall under localized fire exposure

Abstract A full‐scale fire experiment was conducted on a single‐storey steel portal frame to investigate structural behaviour under combined horizontal loading and localized fire exposure. The tested system consisted of a portal frame with thin‐walled purlins and trapezoidal steel sheeting. Prior to fire ignition, a horizontal force of 15 kN was applied to the frame, followed by the initiation of a localized fire beneath the frame near the column. Horizontal displacements of all columns were measured throughout the test. The roof cladding, directly exposed to fire, provided in‐plane stiffness contributing to the horizontal stability of the structure. The governing role was identified in the fastener connections between the trapezoidal sheeting and the cold‐formed purlins, which controlled the effective diaphragm stiffness and its degradation with increasing temperature. The paper primarily presents the mechanical response of the structure, with emphasis on horizontal deformations induced by the applied horizontal force and fire effects. In addition, a pilot test from an experimental programme focused on the stiffness of sheeting‐to‐purlin connections at ambient and elevated temperatures is introduced.