Structural Performance of Tapered Steel Members under Elevated Temperature: Experimental and Numerical Investigations

Abstract

Tapered steel members offer advantages in structural applications due to their material efficiency and their ability to align with nonuniform internal force distributions. However, their fire performance remains insufficiently studied, and design standards provides limited design guidance. This presented research investigates the structural response of tapered steel members exposed to elevated temperatures, with emphasis on strength degradation, stability limits, and residual load‐bearing capacity. A comprehensive experimental program on tapered members subjected to controlled heating is planned to validate the numerical models. Full‐scale tests on beams, columns, and beam‐columns are planned to be performed to capture global instability behavior, and post‐buckling response. In addition, a preliminary numerical study is carried out using nonlinear finite element models incorporating geometric imperfections, large‐deformation effects, and temperature‐dependent steel properties. The influence of taper ratio, cross‐sectional slenderness, and loading regime is systematically evaluated. Local and global buckling modes are identified, and their interaction under fire conditions is quantified. Sensitivity analyses are performed to assess the effects of initial imperfections and thermal gradients. These findings highlight the limitations of current design provisions and support the development of advanced yet economical numerical fire design models and practical guidance for tapered steel members.