Vibrational Analysis of a Metallic Column Submitted to Mechanical Axial Load and Fire Exposure

Vibrational behavior and structural failure of a metallic beam submitted to simultaneous action of axial load and fire exposure are investigated. Analyses are made at ambient conditions and for two types of fire, ISO 834 fire and parametric fire. Vibrational equation based on heat conduction equation and field equations are constructed and numerically solved to obtain the responses in terms of time histories, bending moment in fire and time to failure against axial load ratio. The heat flux is high enough to affect material properties of the structure and their variation with temperature is taking into account in the mathematical formulation. Results show that heat flux resulting from fire action transforms the buckling problem occurring at room temperature into a bending one. Non-reversible responses and sooner arising of failure are observed for ISO 834 fire even for axial load ratio not able to cause buckling at room temperature. Unlike the case of ISO fire, parametric fire improves reversible deflections within the exposure time and later occurring of failure.