Deformation limit states for circular reinforced concrete bridge columns

Through the use of moment-curvature analysis of circular bridge columns, dimensionless serviceability and damage control curvature relationships are developed that depend only on the column axial load ratio and section diameter. These relationships are used to establish curvature, displacement ductility, drift ratio, and equivalent viscous damping capacities for the design limit states considered. It is shown that current code-based design approaches, which imply a constant ductility factor, will generally result in damage levels that are highly variable. The paper also discusses implications of the study on limit-states design approaches such as displacement-based design.