Structural response of a column under eccentric loading in a travelling fire scenario with open ventilation conditions

Abstract

Columns are crucial structural elements designed to carry axial loads. When these loads are applied off the column's central axis, it results in eccentric loading, introducing both axial stress and bending moments in the column. This complexity becomes even more pronounced under transient heating conditions, such as those encountered during travelling fire. In consideration of this, the present study undertakes nonlinear analyses to explore the structural response of columns under eccentric loading and exposed to a travelling compartment fire with open ventilation conditions. The structural response is evaluated considering the effects of eccentricity ratios along the strong and weak axis of the column section for different load ratios. The analysis reveals that critical buckling temperature is higher in travelling fire scenarios compared to standard fire condition. However, when load ratios exceed 0.4, travelling fire become more critical, leading to reduced critical buckling temperature. Furthermore, the vulnerability of columns to fail under eccentric loading is influenced by the degree of eccentricity, load ratio, and the axis of loading. The columns along the strong axis being more prone to global buckling and those along the weak axis exhibiting localized failure. The study shows that failure modes differ between standard and travelling fire scenarios. In standard fire, failure occurs at mid-height, while in travelling fire case, it concentrates in the lower section of a column. Based on the analysis results, an analytical approach is proposed to estimate critical temperature while considering eccentricity and load ratios.