Prestressed concrete bridges appeared in 1930s, and have made great progress since 1950s. Its main span is 90 meters, and now it has an absolute advantage in the middle and small span. In a large span, it competes fiercely with steel bridges. It is a bridge whose main load-bearing structure adopts prestressed reinforced concrete structure.
Extended data
1, the tension control stress of prestressed reinforcement must comply with the design regulations.
2. When prestressed tendons are tensioned by stress control method, they should be checked by elongation value. The difference between the actual elongation value and the theoretical elongation value should meet the design requirements; When there is no provision in the design, the difference between the actual elongation value and the theoretical elongation value should be controlled within 6%. Otherwise, the tensioning shall be suspended until the reasons are found out and measures are taken.
3. Prestressed tensioning shall be adjusted to the initial stress (σo), which shall be 10% ~ 15% of the tension control stress (σcon), and the elongation value shall be measured from the initial stress.
4. The anchorage of prestressed tendons should be carried out under the stable tension control stress, and the internal shrinkage of prestressed tendons at the tension end should not be greater than the design or specification requirements during the anchorage stage.
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