Development of design procedures for the flexural strength and ductility of reinforced concrete bridge columns

The assumptions and methods of analysis used to define the flexural strength and the available limit curvature of reinforced concrete columns sections are discussed. The results of cyclic moment-curvature analyses of a large range of reinforced concrete column sections, using cyclic stress-strain relationships for the steel and for the concrete, are outlined and the important variables and their influence on the available strength and curvature ductility are identified. Examples of design charts derived from these analytical results are discussed and a flow chart outlining the whole seismic resistance design procedure for bridge piers is introduced. The quantity of confining steel determined using the design charts is compared with the corresponding quantity required by the current New Zealand concrete design code equations. Finally a possible future development is discussed that would lead to an improvement of the code design method used to provide sufficient ductility in the plastic hinges of reinforced concrete columns.