Strengthening Prestressed Concrete Box Girder Bridges

The construction of the famous prestressed concrete bridges over the Marne by Eugène Freyssinet, just after the end of the Second World War, was the starting-point of the construction of thousands of prestressed concrete bridges in France. At the time of construction, the danger of corrosion of prestressing cables was underestimated. Too little importance was attached to the proper execution and inspection of grouting, and waterproofing membranes considered unnecessary on prestressed concrete decks. No structural disorders have appeared in the other bridges strengthened by additional prestressing. Therefore this method of strengthening seems to be very effective, even if more time is needed to judge its ultimate durability. To promote this method in France, a standard giving specifications strengthening by additional prestressing has been published.