Adaptive Reliability Analysis of Reinforced Concrete Bridges Subject to Seismic Loading Using Nondestructive Testing

Abstract

Seismic fragility reflects the reliability of a structure to withstand future seismic demands. It is defined as the conditional probability that a structural demand attains or exceeds a specified capacity level for given values of earthquake intensity. In order to obtain an accurate assessment of the seismic fragility, it is critical to incorporate information about the current structural properties, which reflects possible aging and deterioration. This paper proposes an adaptive reliability analysis of bridges using the actual structural properties identified through nondestructive testing (NDT). The proposed methodology combines global and local damage detection methods. Global damage detection uses the dynamic responses of a structure obtained from a vibration NDT to assess the global/equivalent structural properties of the structure and detect potential damage locations. Local damage detection uses local measurements from an NDT technique to identify the local characteristics of the structure at a selected area. Measurement and modeling errors are considered in the formulation of the damage detection methods. The information obtained from the damage detection can be used in available probabilistic capacity and seismic demand models to estimate the seismic fragility of a structure. As an illustration, the proposed probabilistic framework is applied to two example reinforced concrete (RC) bridges. The results show that considering typical values of the structural properties that do not reflect the actual aging and deterioration might lead to significant inaccuracies in the fragility estimates, indicating the importance of adaptive reliability analysis (ARA) in the structural performance evaluation.