Effect of Climate Change on Thermal Loads in Concrete Box Girders

Throughout their service life, bridges are exposed to ambient actions and environmental influences such as wind, thermal, and snow loads. Bridge design for environmental actions is currently based on observed, historical climate data. However, the effects of climate change have put these guidelines into question due to the ongoing and projected change in climate conditions. Bridge engineers are adapting current guidelines and design provisions to incorporate climate change. The main challenges encountered in this endeavor are the nonavailability of future climate data in the required format and the ability of bridge engineers to access and use these data as needed. The focus of this study is to investigate the effect of climate change on thermal load. The objective is achieved through the development of a methodology that can be used to model future hourly climate data; these may be input as boundary conditions in a thermal finite-element model to determine the thermal load acting on a bridge. To demonstrate the methodology, future climate conditions are projected for two locations across Canada (Toronto and Whitehorse), whereas the resulting thermal loads acting on the bridge are determined during heat waves, cold waves, and periods of high daily temperature variation. The results show that climate change could lead to a significant increase in the magnitude of thermal loads on bridges. It is also shown that the effects of climate change on the thermal load vary significantly depending on the general circulation model used, the emission scenario, and the location.