EFFECTS OF GEOTECHNICAL UNCERTAINTY ON THE SEISIMC PERFORMANCE OF BRIDGES

Soil originates from the disintegration of rock and is influenced by the dynamics of geological processes, which are not confined to a specific area or time. Consequently, soil exhibits changes in the spatial distribution (vertical and horizontal) of its geomechanical parameters. This phenomenon, known as spatial variability, is a source of uncertainty in geotechnical engineering problems. Such uncertainty is classified as random heterogeneity (geotechnical uncertainty) inherent to the natural composition of the soil. In this context, structures such as bridges may have their foundation systems in soil with different conditions due to spatial variability. This can affect the dynamic behavior of bridges during seismic events due to varying soil-structure interactions. Although this is acknowledged in geotechnical engineering, theoretical representation and the corresponding analysis of geotechnical problems have predominantly been limited to homogeneous and deterministic evaluations (i.e., considering geomechanical parameters as unique values for large soil volumes). Accordingly, this study addresses the effects of geotechnical uncertainty on the seismic performance of a simply supported, five-span bridge with piles as the foundation system. Random fields are defined using Cone Penetration Test (CPT) data from the bridge site, enabling the determination of spatial and uncertain geomechanical parameters controlling the interaction between the soil and bridge piles. In conclusion, this comprehensive analysis highlights the importance of considering geotechnical uncertainty when evaluating the seismic performance of bridges. Moving beyond conventional homogeneous and deterministic approaches, the study offers valuable insights into the potential effects of geotechnical uncertainty on the seismic performance of bridges considering soil spatial variability.