Ductility of rectangular reinforced concrete columns with axial load.

An experimental investigation into the post-elastic ductile behaviour of reinforced concrete columns designed according to the requirements of the Draft New Zealand Code of Practice for the Design of Concrete Structures was undertaken. Four full size column sections were built and subjected to a static cyclic lateral load sequence over a range of axial compressive load levels. Ductility requirements of reinforced concrete columns are discussed and the results and analyses of experimental results are presented. Results are presented in the form of measured lateral load - displacement and moment - curvature relationships, curvature and longitudinal bar strain profiles, and transverse confining steel strains. Analysis of results includes the comparison of measured ductilities, plastic hinge lengths, concrete spalling and maximum compression strains, and stress-strain curves for confined concrete with those obtained by existing analytical methods. Conclusions are made about the effectiveness of the confinement provided by the draft code recommendations.