Method for construction of high upper beam steel oblique leg prestress support of H-shaped cable bent tower of cable-stayed bridge

Abstract

The invention discloses a method for construction of a high upper beam steel oblique leg prestress support of an H-shaped cable bent tower of a cable-stayed bridge and belongs to the field of bridge construction. According to the method, a steel oblique leg bracket and a lagging jack are adopted for construction of a beam, installation and dismantling of a large number of steel pipe supports when a high support construction method in the prior art is adopted are avoided, the workload of pre-buried piece installation during cable bent tower construction and the workload of repair in the later stage are reduced, the high-altitude welding workload and materials are reduced, the risk of aloft work is greatly reduced, and the problem that the reserved compression amount of the high support and the camber of a pre-buried bracket support are difficult to set is solved; stress of the steel oblique leg bracket is clear, an upper joint transmits a vertical load to the cable bent tower, the horizontal outward component force of obliquely-downward force on a lower joint is counteracted by prestressing force pre-applied by a prestress wire close to a horizontal tie bar, and the vertical component force of the obliquely-downward force on the lower joint is borne by the cable bent tower. In addition, the cable bent tower and the beam are constructed asynchronously, a cable bent tower formwork does not need to be constructed on the side provided with the beam, high-altitude dismantling and installation of a climbing fame are omitted, the safety risk is lowered, and the construction cycle is shortened.

Description

technical field [0001] The invention is used in the field of bridge construction, and in particular relates to a construction method for a steel oblique leg prestressed support of an H-type cable tower of a cable-stayed bridge with a high upper beam. Background technique [0002] The cable-stayed bridge is one of the most important bridge types of long-span bridges. The construction of the H-type cable tower beam of the cable-stayed bridge is a key and difficult part of the cable-stayed bridge construction. A high-risk segment. During the construction of the high upper beam, formwork installation, steel bar binding, prestressed pipe installation, concrete pouring and other work are all carried out on the upper beam bracket. Therefore, the design and installation of the upper beam bracket should be as simple and safe as possible. [0003] H-type cable tower high beam construction is very common in the current construction of cable-stayed bridges. There are generally two con...

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Problems solved by technology

[0006] 1. A large number of high-altitude steel pipe supports need to be erected. The installation and dismantling of the hoisting workload is heavy, and the high-altitude welding workload is heavy. There is a great risk of high-altitude operations, and the installation and disassembly of steel pipe supports takes a long time.

[0007] 2. When the distance between the high upper beam and the top surface of the lower beam is far, it is necessary to install multiple brackets attached to the wall at a certain distance, resulting in the installation of a large number of embedded parts during the construction of the cable tower, and the position of the embedded parts needs to be adjusted after the bracket is removed. Repairing will greatly increase the difficulty and safety risks of the cable tower decoration work, and will also affect the beauty of the cable tower

[0008] 3. The steel pipe of the high support is long, and the compression of the steel pipe support is large when the upper beam is poured, and a large compression value needs to be reserved for the support

[0012] 2. The middle span of the pouring arch is too large, and the arch will have a large deflection during concrete pouring. It is troublesome to set the camber during construction. If the rigidity of the arch is to be ensured, the arch will be too heavy

[0013] 3. The pre-embedded corbel bracket is mainly supported by welding corbels. Large corbel pre-embedded parts need to be installed during cable tower construction, which is difficult to install. When welding large corbels, the welding workload is large and the construction is at high altitude. It is difficult to guarantee the quality of the weld seam, and it is difficult to inspect the weld seam (or use a special instrument to detect it)

The dismantling and installation of formwork and bent frames at high altitude is cumbersome and has a high safety risk; and the simultaneous construction of the upper beam and the tower column of the corresponding height and the disassembly and assembly of high-altitude formwork and climbing frames seriously affect the construction period of the cable tower

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