Fatigue life assessment on composite concrete-steel bridges

Abstract

Fatigue is an important consideration in the design of bridges, especially those made of steel. Cycles resulting from the passage of a truck over a bridge depend essentially on bridge type, detail location, span length and vehicles axles configuration. Moreover, as bridges form the keystone of transport networks, their safe operation with minimal maintenance closures is paramount for efficient operation. Yearly increases in the volume of heavy traffic mean a higher number of fatigue damaging load cycles, which leads to taking appropriate measures and finding sustainable solutions, with reduced environmental, economic and social impacts.This work is focused on developing a software tool for the design and assessment of composite concrete-steel bridges under fatigue, according to Eurocodes. The type of bridge used for this project is limited to a road-girder-bridge. Design approaches include both the damage equivalent factor method and the damage accumulation method. For the latter, an algorithm was developed which simulates truck passages over a bridge model and calculates fatigue load effects using the axle positions recorded in real time. This information could serve as an identification tool for bridges where fatigue is likely to be a problem and could form part of a full bridge management framework in the future.Furthermore, the program is applied into a real case study, in order to compare the results and evaluate its efficiency and accuracy. Finally, conclusions are drawn and future work is proposed, leaving space for improvements and new challenges.

Fatigue is an important consideration in the design of bridges, especially those made of steel. Cycles resulting from the passage of a truck over a bridge depend essentially on bridge type, detail location, span length and vehicles axles configuration. Moreover, as bridges form the keystone of transport networks, their safe operation with minimal maintenance closures is paramount for efficient operation. Yearly increases in the volume of heavy traffic mean a higher number of fatigue damaging load cycles, which leads to taking appropriate measures and finding sustainable solutions, with reduced environmental, economic and social impacts.This work is focused on developing a software tool for the design and assessment of composite concrete-steel bridges under fatigue, according to Eurocodes. The type of bridge used for this project is limited to a road-girder-bridge. Design approaches include both the damage equivalent factor method and the damage accumulation method. For the latter, an algorithm was developed which simulates truck passages over a bridge model and calculates fatigue load effects using the axle positions recorded in real time. This information could serve as an identification tool for bridges where fatigue is likely to be a problem and could form part of a full bridge management framework in the future.Furthermore, the program is applied into a real case study, in order to compare the results and evaluate its efficiency and accuracy. Finally, conclusions are drawn and future work is proposed, leaving space for improvements and new challenges.