I came across this problem last year. Although the
issue has been solved, still I think we can share our views on this.
The problem occurred on
19m long pre tensioned PSC beam. The
cracks, in the range of 0.2 mm – 0.5 mm, were
noticed on the top flanges of the 19 m beams and near the two lifting positions of the each side
ends of the beams as shown in the following figure.
 |
| cracks positions of the beam |
 |
| closed view of the cracks |
The crack positions,
sizes and the propagation are almost identical in every beams at the site and I had my uncertainties on the structural integrity of the defected beams.
The cracks have appeared
on the places where maximum hogging moment occurs during the lifting of beams.
Hence these are considered as flexural cracks ( Not shrinkage or
early thermal cracks) and possibly owing to lifting of the beams before the
concrete achieve its characteristic strength in Transfer Stage.
I would highly welcome your opinion on what next to do?
