Abstract: Most of the iron and steel bridges in Sri Lanka are more than 100 years old. Since many of them are
reaching or exceeding their design lives, the risk of collapsing those bridges have increased. One of the probable
damages which bridges experience due to increasing traffic volume as well as environmental degradations such as
corrosion is the corrosion fatigue failure. This problem is severe in bridges located in industrial areas and along the
coastal line of the country. Corrosion and corrosion fatigue made a huge attention in the recent past due to many
failures of bridges all over the world.
This paper presents a study conducted on assessing the corrosion fatigue damage of steel bridges. It proposes a
procedure developed using existing fatigue and corrosion models for evaluating the remaining fatigue life. The
procedure includes condition surveys, field loading tests, finite element modelling and analysis, developing S-N
curves for different atmospheric conditions, use of corrosion rates and assessing cumulative fatigue damage. The
paper also presents a case study: a century old iron and steel (mild steel and wrought iron) railway truss bridge
damaged by both corrosion and fatigue. Using details of condition survey, load testing, appropriate corrosion data,
finite element modelling and a corrosion fatigue assessment procedure, the remaining life of the bridge was evaluated
for two atmospheric conditions; (i) corrosive atmosphere and (ii) noncorrosive atmosphere. The results of the
evaluation were then compared to show the impact of the atmospheric condition on the fatigue life of the bridge
