Prefabrication method of prestressed concrete beam and prestressed concrete beam

Abstract

The invention relates to the technical field of prestress structures, and discloses a prefabrication method of a prestressed concrete beam and the prestressed concrete beam. The prefabrication methodof the prestressed concrete beam comprises the steps that S1, a protection device is mounted on a prestressed tendon needing forced prestress failures and is used for isolating the prestress failure segment of the prestressed tendon from concrete; S2, the tensioning force of the prestressed tendon is released; S3, the protection device is filled with an anti-corrosion material, and the prestressedtendon is wrapped; and S4, the end of the cutoff prestressed tendon is blocked. The protection device is mounted on the prestressed tendon needing forced prestress failures and isolates the prestressfailure segment of the prestressed tendon from the concrete so as to achieve the prestress failure function, the prestressed tendon can serve as a common steel bar, and the anti-crack function of theprestressed tendon is achieved; and the protection device is filled with the anti-corrosion material, the prestressed tendon is wrapped so as to achieve the anti-corrosion aim of the prestressed tendon, the durability performance of the prestressed tendon is improved, and then the anti-crack performance of the concrete is improved.

Description

technical field [0001] The invention relates to the technical field of prestressed structures, in particular to a method for prefabricating a prestressed concrete beam and a prestressed concrete beam. Background technique [0002] During long-term use, transverse and oblique cracks gradually appear on the end of the prestressed concrete hollow slab beam and the bottom surface of the beam, and these cracks are just in the transition section between the prestressed effective zone and the failure zone of the prestressed tendons. After peeling off the concrete protective layer in this cracked area, it was found that some prestressed tendons were corroded, concrete swelled and cracked, and more seriously, prestressed tendons were corroded to fracture. The reason is that the prestressing failure measures of the prestressing tendons at the prestressing failure section at the end of the beam have the following defects: [0003] (1) When the prestressed tendons are stretched and rel...

AI Technical Summary

Problems solved by technology

[0003] (1) When the prestressed tendons are stretched and released, there is stress concentration in the prestressed tendons in the bottom plate in the transition section between the end prestressed effective area and the failure area, and the prestressed tendons and concrete in the prestressed failure section are used The outer PVC pipe is isolated, resulting in insufficient concrete reinforcement ratio in the prestressed failure area, and the concrete is cracked;

[0004] (2) The PVC pipe waterproof measures of the prestressed tendons in the prestressed failure section are flawed, resulting in the water on the bridge entering the PVC pipe, and the prestressed tendons in the PVC pipe have been eroded by accumulated water for a long time, and finally the prestressed tendons are corroded and broken, and the concrete protection Layer swelling and cracking;

[0005] (3) There are two types of prestressed tendons passing through the prestressed failure zone at the end of the prestressed concrete hollow slab beam, one is the prestressed tendons that artificially force prestressed failure, and the other is the prestressed tendon that must maintain the effective prestressed The prestressed tendons that fail to be artificially prestressed are corroded and broken due to defects in the PVC pipe, and the concrete cover is swollen and cracked. Another type of prestressed tendons that must maintain effective prestressing in this area is wrapped around the surface. The concrete is affected by the damage and is forced to crack and peel off. It is difficult to guarantee the effectiveness of the prestressing force. At the same time, there are large areas of cracks in the concrete in this area, and the durability of the prestressing tendons is reduced. Eventually, the two types of prestressing tendons will tend to corrode and break. The failure of the body's bearing capacity endangers the safety of the structure

This is not only a waste of resources, but also requires interruption of traffic, high cost and long construction period

Especially if this type of bridge crosses special structures, such as railways, military facilities, etc., it is more difficult to dismantle and rebuild, the cost is higher, and the construction period is longer

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