Page 373 - Failure Analysis Case Studies II

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Fig. 1. Prestressed concrete construction of the viaduct.

,,-r , Main load - bearing
~
l-,
beam
longitudinal

1 cable = 12 prestressing hires
Fig. 2. The arrangement of cables in the longitudinal beam.

2. EXPERIMENTAL INVESTIGATIONS AND DISCUSSION

Out of all the samples of prestressing wire of 7 mm diameter and strength class 1800 N/mm2
which had been removed from the beams of the viaduct, a selection of samples was made showing
different degrees of corrosion, from samples that appeared to be intact with a zero degree of
corrosion, up to samples which showed heavy corrosion defined by a corrosion degree of “5”. The
corrosion degree (“Corr. d.”) was expressed by means of the actual cross-section, which represents
the change from the initial, uncorroded condition. These specimens were tested to failure in a tension
testing-machine in order to determine their mechanical characteristics, including the elongation,