ABSTRACT
A reliability-based rating of the BS8110 (1985) design criteria for reinforced concrete columns is attempted in this thesis. 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. All the basic design variables involving cross-sectional resistance and loading are treated as random variables with their statistical characters adopted from literature. The results show that the BS8110 (1985) design requirements are highly inconsistent and very conservative having a range of reliability index, 0, from 1.04 to 8.03. Considering varying practical values of the decision variables, the code provides an average 0-value of 4.35 (i.e. pf = 6.79 x 10-6) for the different columns studied. It is also found that the criterion for the design of short columns in biaxial bending is the most inconsistent and conservative while short columns with bending have the least indicating a better capacity prediction. Sensitivity analyses show that the 0-values for axially loaded short columns are influenced most by cross-sectional dimensions and load while for short columns with bending and slender columns the effective depth is the most influential. The 0- values for short columns in biaxial bending is influenced substantially by all design variables except concrete strength and concrete cover. The work concludes by providing some sample charts suitable for designing to specific reliability levels.