Soil-structure interactions of integral abutment due to thermal action : relationship between effective bridge temperature and ambient temperature

Integral abutment bridges have become an increasingly popular choice of bridges to construct in many countries, including Australia. This is mainly because integral abutment bridges are constructed without any joints in the bridge deck and therefore avoid many of the recurring maintenance issues that bridge joints cause. In the absence of bridge joints, however, the expansion and contraction of the bridge deck in integral bridges are transferred to the bridge ends, which interact with the surrounding backfill and soil. The soil-structure interactions result in aggravated lateral stress ratcheting and soil slumping at the bridge approach, which impact negatively on the integral abutment. The effects of soil-structure interactions caused by thermal displacement of integral bridge due to the diurnal and seasonal temperature changes accumulate over several years. Accurate prediction of soil-structure interactions therefore relies on accurate estimation of thermal displacement of the integral bridge. However, most bridge expansion/contraction estimation methods due to temperature changes are developed for expansion joint purposes and are not suitable for integral bridges. Abaqus was used in this study to analyse the heat transfer in a concrete bridge and compute the spatial temperature distribution of the bridge section. Long-term 2-year Australian Bureau of Metrology weather data was used in the simulation to establish the relationship between effective temperatures attained in the bridge section and the ambient temperatures. The results would be useful to inform on the correct temperature inputs to use in predicting the thermal displacement of integral bridge.