In this contribution we illustrate an application of Bayesian logic to the analysis of monitoring data and the inference of structural condition.The case study is a 260 m cable-stayed bridge spanning the Adige River 10 km north of Trento,Italy.This is a statically indeterminate structure,with a composite steel-concrete deck supported by 12 stay cables.Structural redundancy,possible relaxation losses and an as-built condition differing from design suggest that long-term load redistribution between cables can be expected.Consequently,the owner installed a monitoring system that includes fiber-optic sensors based on Fiber Bragg Grating technology (Zonta et al.2011,Glisic & Inaudi 2007).These sensors allow measurement of deformation with an accuracy in the order of about 5 με,with respect to the value at installation.