The paper gives an overview of the pre-stressing systems used in the former GDR and describes one system, called ITB, in detail. During the demolition of the bridge "10. Jahrestag" in Neubrandenburg, at which this pre-stressing system was first used, material samples and a specimen were taken and experimentally investigated. For the objective of the investigation of a pre-stressed concrete element without non-pre-stressed reinforcement, a cut out beam of a bridge was loaded until failure and different measuring technologies, like the photogrammetry, the acoustic emission analyses and the sectionwise curvature-measurement were used. The results of this experimental investigation are discussed in detail and the bearing behavior according to an unannounced failure is evaluated.