Author(s) :

O.A.U Uche, J.O Afolayan.

Volume/Issue :

Abstract :

The provision of safe structural system has always been a major object of a structural design. This paper presents a Reliability-based rating of the BS8110 (1985) design criteria for reinforced concrete columns. The rating is based on the First-Order Second Moment Integration Technique. Limit state equations for axially loaded short columns, short columns with bending, slender columns and short columns subjected to biaxial bending are derived and their implied reliability levels evaluated using the First - Order Reliability Analysis (FORA). All the basic design variables involving cross-sectional resistance and loading are treated as random with their statistical characters adopted from literature. It is found that the BS 8110 (1985) requirements are seemingly inconsistent and very conservative at high reinforcement ratios. The implied safety indices derived vary from 0.05 to 8.52 with an average of about 4.29 (i.e., Pf=5.5x10-6). Also established is that the current requirements lead to the fact that more reinforcement will be needed for short columns with bending than when axially loaded at the same dead to live load ratio. However, columns supporting beams with uniform distributed loading require less reinforcement than those supporting beams with concentrated loads. The functions are provided in charts for design purpose.

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