Sensitivity of Seismic Assessment of a Double-Deck, Reinforced Concrete Bridge

Engineers are assessing the seismic vulnerability of thousands of reinforced concrete bridges located throughout the United States. Many of the bridge evaluation procedures are new, and the engineering effort necessary to implement them varies. Consequently, the assessment methodology varies among the responsible agencies, and in some cases, from one bridge to the next. This paper documents the sensitivity of an evaluation of a double-deck, reinforced concrete bridge to the manner in which the assessment was conducted. Large differences arose from the selection of linear versus nonlinear models. The computed splice vulnerabilities and concrete contribution to shear capacity varied also. In contrast, the assessment results were relatively insensitive to the way in which the investigators estimated the flexural ductility capacities, the transverse reinforcement's contribution to shear resistance, and the joint vulnerability. Even if the variations among the evaluation procedures are reduced, the results of the evaluations will still be sensitive to the selection of the ground motion and foundation stiffness.