Investigation on the mapping for temperature-induced responses of a long-span steel truss arch bridge

Temperature-induced bridge responses are highly sensitive to changes in bridge properties. Thus, the relationship between temperature and associated responses can be used as a surrogate to assess the health of bridges. However, the relationship between temperature and temperature-induced displacement is influenced significantly by bridge bearing properties. The temperature variation cannot cause longitudinal displacements until the longitudinal restraint of bearings is overcome. Additionally, the temperature-induced strains highly depend on spatial temperature distributions in bridges. The developed mappings seldom consider the aforementioned issues, resulting in errors that can conceal the variation produced by the changes in bridge conditions. Focusing on long-span steel truss arch bridges with spherical bearings, this study seeks to accurately map the temperature-induced responses considering the bearing properties and spatial temperature distributions. The relationship between temperature variation and temperature-induced responses is explored initially using the elastic beam theory. Subsequently, the mapped relationship is validated using field monitoring data. Results show that the relationship produces unique flat planes in 3 D space; the plane parameters, including the orientation and boundary, are determined by the structural parameters, especially the bridge cross-section properties and bearing properties. Accordingly, the 3 D baseline can provide a feasible signature for bridge conditions.