THE MYSTERY OF THE NOISE OF SOME OLDPRESTRESSED CONCRETE BRIDGES NOWCLEARED UP

Abstract

During the inspection of different prestressed concretemotorway bridges, some cracks near the anchorage ofprestressed units could be heard. An internet site gives samplesof those rare noises which could be heard on a viaduct. Thosebridges are all equipped with the same type of prestressed units.Various tests in laboratory but also on site, such as radioscopy,measurement of displacement, strains and accelerations, hadbeen undertaken to understand the reasons and causes for suchnoises. Some of those tests have been undertaken 35 years afterthe first test. The source of the noises had now been localisedand their causes are known. We noticed that as the strandscould be submitted to fatigue, it has to be taking intoconsideration. The reinforcement of the viaducts by externalcables (needed for other reasons too) leads to the long-termending of the issue.