Case studies on determining fire resistance of uniaxial bending reinforced concrete columns subjected to 4-side standard fire exposure

This article introduces technical specifications and calculation instructions for fire resistance of uniaxial bending rectangular reinforced concrete (RC) columns under 4-side heating by standard fire. Although a number ofresearch works have been conducted following the Eurocodes to meet the long-term requirement of the country’s development in construction, it is shown that the Russian design standard SP 468.1325800.2019 (SP 468) is also applicable for concrete structures subjected to fire in the Vietnam current context. Tabulated data and simplified calculation methods according to SP 468 are introduced, followed by two practical case studies for demonstration. The calculation results show that by using the simplified calculation method the RC columns’fire-resistant limit can be explicitly determined with a particular safety factor ku, T, and a more economical design solution can be obtained compared to that of the tabulated data method. Additionally, RC columns loaded with small eccentricities exhibit greater fire resistance advantages compared to those with large-eccentricity loading. A number of other useful observations are also discussed in the latter part of this article.