LifeExt - Prolonged life for existing steel bridges

Purpose and goal

LifeExt should enable life extension of existing bridges by applying enhancement techniques to critical details. Here, the damage accumulation is faster and through local improvement, a significant increase in life can be achieved for the entire bridge. The goals were: Study the possibility of “locally re-welding” a crack. Evaluate possible NDT methods. Explore the possibility of using HFMI methods to restore fatigue life. A damage model should be developed. All objective are met and initial recommendations have been made. The damage model is in good agreement with the data.

Expected results and effects

The results are very good, partly even above expectations. The effects cannot yet be seen as the results are spreading now. But it is expected that the life-enhancing technologies studied will be of great benefit - especially when followed up and supplemented with additional results and methods (more methods are available and further cases need to be elucidated). Webcast of results and discussions with the Swedish Transport Administration took place today with large participation. The results were received very well and it was discussed how quickly the regulations can be updated.

Planned approach and implementation

The project has largely followed the original idea, but not the plan. The testing has taken significantly longer than planned since the specimens were of high quality, so the life extension judgments are conservative. The testing has therefore been allowed to run full, except for the last month. The results that emerged were so interesting that additional (!) samples were produced and run, despite rather short time remaining. This gave very good results and analysis possibilities for the damage model, so the project group is very satisfied despite the reporting being pushed at the end.