The cracking of prestressed girders influenced by decreased bond of tendons

The time between prestressing of tendons in concrete post-tensioned bridges and the injection of ducts usually takes several weeks. Tendons are protected against weathering and atmospheric humidity with various agents, the presence of which influences the bond of tendons with a structure. This bond can also influence the durability of prestressed bridge in view of cracking. Bonded tendons in the tension zone may be assumed to contribute to crack control. This may be taken into account by assuming the ratio of bond strength of prestressing and reinforcing steel. The paper deals with evaluation of crack pattern of experimentally investigated post-tensioned members. These are the two span post-tensioned girders with different bond behavior of prestressing units. Together three different tendon types were investigated. Unbonded tendons, fully bonded tendons and tendons with decreased bond (caused by corrosion protection coatings).