Reliability of RC cross-sections designed for simple bending according to the 2014 and 2023 versions of NBR 6118 code

Abstract

This article presents a comparative study of the reliability of reinforced concrete (RC) cross-sections subjected to simple bending, designed at the ultimate limit state and following the recommendations of the 2014 and 2023 versions of the Brazilian code NBR 6118. The analyses are based on reliability theory by implementing the FORM algorithm on three rectangular cross-section configurations, considering three constant values of dimensionless bending moments and five different concrete strength classes between C30 and C90. Although the elements designed by NBR 6118:2023 have shown additions of up to 19% in the total steel cross-section area as a consequence of the implementation of the strength reduction factor (ηc), the results show no significant improvements in reliability compared to the 2014 previous version of NBR 6118.