Broken-line reinforcement prestressed concrete pre-tensioned girder construction process

Abstract

The invention relates to a construction process for a pre-tensioned girder with a broken-line prestressed concrete beam. The invention comprises a pulling-tension process and an expanding-tension process, and the pulling-tension process is provided with an upper beam and a lower beam, and a prestressed strand comprises a straight-line steel strand and a broken-line steel strand. The straight-line steel strand is anchored on the lower beam, and the broken-line steel strand is firstly bent by a bending device and then is anchored on the upper beam. And the lower beam and the upper beam are movable beams. The pulling-tension process adopts a two-end tensioning way. The pulling-tension process includes the following procedures: 1, on outer sides of the upper and the lower beams, a jack is respectively used for singly tensioning steel strands on corresponding beams to 30-40 percent of a control stress; 2, on outer sides of the upper and the lower beams, the jack is respectively used for singly tensioning steel strands on corresponding beams to 65-85 percent of the control stress; 3, steel strands on the upper beam and the lower beam are completely and respectively tensioned to 100 percent of the control stress. The invention not only can guarantee an accurate tension tonnage but also can improve the tensioning efficiency, and the construction is safe.

Description

technical field [0001] The invention relates to the technical field of prestressed concrete engineering, in particular to a construction technique for prestressed concrete pretensioned beams with broken line reinforcement. Background technique [0002] Prestressed concrete can be divided into pretensioning method and posttensioning method according to its prestressing process. Among them, pretensioned prestressed concrete is convenient for factory prefabrication, because of its short construction period, simple process, saving materials, and easy construction quality. It has been recognized and promoted for its advantages of less maintenance work and good durability. However, at present, the pretensioning method has only been applied in the prefabrication of straight-line reinforced hollow slab girders used in small-span bridges and approach bridges of some large bridges. , due to the frequent occurrence of cracks in the initial test stage of applying the pretensioning proc...

AI Technical Summary

Problems solved by technology

In the above process, due to the large number of prestressed steel strands, jacks are used to pull the single strands of steel strands one by one to control the stress, which makes the stretching process take a long time, the process is cumbersome, the workload is large, and the construction efficiency is low; In addition, This tensioning method does not take into account the compression loss of the reaction beam, the insufficient tension of some single steel strands and the difference in the tension of each steel strand, which affects the accuracy of the total tension.

The use of jacks and tensioning wedges to release the prestressing force makes the tensioning structure more complicated, the tensioning operation is not easy to coordinate, and it is difficult to ensure synchronous tensioning. In addition, it is prone to wedge sliding, wire running, beam sliding, loosening, etc. Causing collision accidents, release control is unreliable and unsafe

[0004] The above-mentioned prestressed concrete pretensioning technology with broken line reinforcement is applied in railway bridges, but at present, the application of prestressed concrete pretensioning construction technology in highway bridge construction is still blank

Images