Quantifying Material Uncertainty in Seismic Evaluations of Reinforced Concrete Bridge Column Structures

In seismic performance evaluations, the force-deformation response of a structure is typically assessed using a deterministic analytical model, and inherent uncertainty is often neglected. For reinforced concrete structures, a source of uncertainty is variability in the mechanical properties of reinforcing steel and concrete (that is, material uncertainty). This paper presents an analytical investigation to quantify the impact of the statistical variability in mechanical properties of ASTM A706 Grade 60, 80, and 100 reinforcing steel and normalweight concrete on the seismic response of reinforced concrete bridge columns. The effects on the drift response, expressed by the coefficient of variation (COV), range between COV values of 0.1 for low-to-moderate ductility demands (that is, drift ratio < 5%), and 0.3 for larger ductility demands. The COV of the force demand is lower, ranging between 0.05 and 0.1. Overall, the study shows that material uncertainty can be incorporated in seismic performance assessments through a few additional analyses.