Fatigue life evaluation of a through-girder steel railway bridge

Over the recent years, the Marmaray project has come into realization in Istanbul in order to connect the two continents, Europe and Asia, by providing an underwater link for the first time. Some existing steel railway bridges will also be used for the proposed railway infrastructure. The purpose of this study is to identify the factors affecting the remaining effective service life of such a bridge, and possible fatigue life extension. Firstly, the whole structure was inspected visually for any existing damage due to highway traffic passing underneath. Detailed field measurements and in-depth analytical studies were conducted to determine the axle loads and bridge responses under current operating conditions. A statistical description of typical train cars was developed. Using the computer model which was refined by field measurements, the bridge was re-assessed according to expected train traffic for the future. The results were then used to determine the remaining life of the steel railway bridge. In order to improve the fatigue life, a strengthening scheme to extend the service life has been proposed for a typical bridge component.