Design of Reinforced Concrete Columns

Abstract

<p>The design of column cross sections for known axial loads and moments has reached the stage where practical methods give results which agree very closely with tests and with accurate analyses. However considerable uncertainty exists with regard to methods employed to take into account the effects of the additional moments caused by deflection of columns. Theoretical calculations can be used to accurately predict the loads at which material failure or column instability will occur. However designers require simpler techniques which are sufficiently general in nature to be equally applicable to the large variety of design cases.</p> <p>The effect of column slenderness which is further complicated by consideration of creep under sustained load is the main topic of this study. It is suggested that a realistfc appraisal of design methods must be based on the idea of consistent safety factors. Thus slender columns subjected to sustained load must retain sufficient reserve capacity so that failure loads when compared to design loads provide equal safety factors. The National Building Code of Canada is being revised to include tho relevant provisions of tho ACI Standard 318-71(²). Tho columns analysed in this study were designed in accordance with ACI Standard 318-71. Comprehensive evaluation of the design parameters in the ACI method is given in this thesis along with conclusions and comments. It was observed that the ACI method does not yield consistent safety factors for the different values of the design parameters. The analyses and conclusions of this study are given in details in chapters (6) and (7).</p>