Thermal Monitoring of a Concrete Bridge in London, UK

During bridge design and assessment, the effects of thermal actions are accounted for by means of a uniform temperature variation and temperature difference components. The uniform temperature variations cause changes in length and width of the structure, whereas the temperature difference components primarily cause curvatures and internal stresses. The effects of these strains on the superstructure depend on the structure’s articulation and restraint. The design profiles used to model the temperature difference components vary between design codes, which can have a significant effect on the induced curvatures. This paper examines the thermal data findings obtained from a comprehensive, year-long monitoring programme on Waterloo Bridge in London, which allows comparison of these various models with performance data. The design thermal model in BSEN1991-1-5 is examined, supplemented by the models from the AASHTO and New Zealand codes. The measured uniform bridge temperature generally fell within the stipulated limits of BSEN1991-1-5, however at low temperatures the minimum deck temperature may be lower than the design relationship provided. The resultant moments implied from the measured vertical profiles: significantly exceed the worst-case values predicted by the UK model; exceed the AASHTO model at different bridge sections; and do not exceed the New Zealand Model.