Residual strength of reinforced concrete columns with +-shaped cross section after exposure to fire

The practical calculation method for the residual strength of reinforced concrete columns with +-shaped cross section after exposure to ISO834 standard fire is investigated. Using a numerical program CAFIRE, the influence of several parameters, such as exposure times, effective lengths, sectional thicknesses, ratios of sectional height to sectional thickness, load eccentricity ratios, reinforcement ratios, load angles and longitudinal reinforcement yield strength on the residual strength of RC columns with +-shaped cross section after exposure to fire is analyzed. 14580 columns with +-shaped cross section and subjected to fire in all sides were selected for residual strength analyses. Based on the calculation results, a simplified calculation method is proposed for the residual strength of +-shaped columns after exposure to ISO834 standard fire.