Prefabricated box girder reinforcement cage forming method suitable for factory manufacturing

Abstract

The invention discloses a prefabricated box girder reinforcement cage forming method suitable for factory manufacturing, which is characterized in that a box girder reinforcement cage obtained by assembling an existing closed hoop is improved into a structure of a bottom web double-U mesh and a top plate double-layer mesh according to a'double-U + top plate 'forming and assembling thought; each type of reinforcing mesh can be automatically produced by bending, binding and welding equipment at the same time, the mesh is moved to a reinforcing steel bar framework assembling area through a special lifting appliance to form a box girder reinforcing steel bar framework, and meanwhile prestressed pipeline strand penetrating installation is carried out. The construction quality problems of strand pulling displacement, deformation damage and the like of the prestressed pipeline are solved, the subsequent prestressed tension safety quality is guaranteed, and the service life of the prefabricated PC box girder is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge engineering construction, and in particular relates to a method for forming a prefabricated box beam reinforcement skeleton suitable for factory manufacturing. Background Art

[0002] Prefabricated prestressed concrete box girders are widely used in highway and railway bridge construction as a safe and reliable bridge structure. In the existing PC box girder prefabrication technology, the steel skeleton is mainly made by bending individual steel bars, assembling them in sequence, and manually tying them at the intersection to form a steel skeleton. The skeleton is then hoisted into an external formwork for pouring. Although this construction method is simple and easy, it is inefficient and requires a lot of manpower. Due to the uneven technical level of workers, the operation process is prone to missing steel bars, exposed steel bars, and deformation, which makes the construction quality of the steel bars unguaranteed and poses a high safety risk. Before pouring construction, the prestressed pipes need to be manually inserted into the assembled steel skeleton and fixed. However, due to the large number of complex steel bars at the bottom web nodes and the small construction space, pipe deformation, breakage, blockage and other construction defects are inevitable, causing durability problems during the bridge operation phase.

[0003] With the increasing aging of my country's population and the continuous advancement of intelligence in the field of construction technology, inefficient manual bending, binding, and hoisting operations, as well as on-site casting and maintenance of box girder construction technologies that create dust and sewage, have become major obstacles to the industry's progress.

[0004] As on-site box girder construction methods evolve towards automated, low-carbon, and environmentally friendly factory-prefabricated PC box girder manufacturing, the closed-loop reinforcement within the existing steel skeleton interferes with each other, preventing full-process mechanized bending, welding, and tying. Furthermore, conflicts exist between the prestressed conduit routing process for the box girder and the automated rebar layout. These issues can only be addressed manually, significantly reducing work efficiency and making it impossible to adapt to the low-labor, factory-based manufacturing of the steel skeleton, thereby preventing the rapid, low-labor, and green construction model currently used in bridge construction. Summary of the Invention

[0005] In order to overcome the technical problems in the prior art of prefabricated prestressed concrete box girder construction process, in which the closed-loop reinforcement in the steel skeleton affects each other and the full-process mechanized bending, welding and binding cannot be achieved, the present invention provides a prefabricated box girder steel skeleton forming method suitable for factory manufacturing. With the idea of ​​"double U + top plate" forming and assembly, the box girder steel skeleton obtained by assembling the existing closed hoop is improved to a bottom web double U mesh + top plate double-layer mesh structure. Each steel mesh can be automatically produced by bending, binding and welding equipment at the same time. The mesh is moved to the steel skeleton assembly area by a special hoist to form a box girder steel skeleton, and the prestressed pipe bundle is installed at the same time, thereby solving the above technical problems.

[0006] The prefabricated box girder reinforcement skeleton is divided into a double U + top plate mesh structure. The main body is composed of the outer U-shaped mesh of the bottom web, the inner U-shaped mesh, the lower mesh of the top plate, and the upper mesh of the top plate. Through sequential assembly and with the help of the bottom plate mesh frame reinforcement, the bottom web corners are reinforced with the first reinforcing steel bar, the U-shaped tie steel bars at the bottom web corners, the web prestressed pipe positioning steel bars, the web mesh frame reinforcement, the inner U-shaped mesh and the lower mesh of the top plate are reinforced on the outside with the second reinforcing steel bar, the second reinforcing steel bar and the top plate mesh frame reinforcement, the inverted U-shaped steel bars at the web nodes form a complete box girder reinforcement skeleton.

[0007] The above-mentioned method for forming a prefabricated box girder steel frame suitable for factory manufacturing, wherein the lower mesh of the prefabricated box girder top plate and the upper mesh of the top plate are formed by sequentially placing longitudinal and transverse steel bars and automatically binding and welding them by robots to form a flat mesh, and the two long sides are bent by an automatic bending machine, and assembled with the top plate mesh frame steel bars to form a double-layer equivalent closed mesh steel frame of the top plate.

[0008] The above-mentioned method for forming a prefabricated box girder steel frame suitable for factory manufacturing, wherein the outer U-shaped mesh and the inner U-shaped mesh are assembled in sequence and the bottom plate mesh frame steel bars, the first reinforcing steel bars of the bottom web, the U-shaped tie steel bars at the corners of the bottom web, the positioning steel bars of the web prestressed pipes and the web mesh frame steel bars form a double-layer U-shaped mesh structure of the bottom web.

[0009] The above-mentioned method for forming a prefabricated box girder steel frame suitable for factory manufacturing, wherein the first reinforcing steel bar is placed on the inner side of the inner U-shaped mesh of the web, and the U-shaped tie steel bars at the corners of the bottom web pass through the outer U-shaped mesh of the bottom web from the inside to the outside, and the inner U-shaped mesh of the bottom web is fixed.

[0010] The above-mentioned method for forming a prefabricated box girder steel frame suitable for factory manufacturing, wherein the outer U-shaped mesh and the inner U-shaped mesh are connected to the upper mesh of the top plate, the lower mesh of the top plate, and the inverted U-shaped steel bars at the web node by binding or welding to form a top and web steel frame node, and the outer U-shaped mesh and the inner U-shaped mesh extend out of the outer contour of the concrete.

[0011] A method for forming a prefabricated box girder reinforcement skeleton suitable for factory manufacturing, the method comprising the following construction steps: S1: The automatic steel bar straightening machine extracts the steel bars from the steel bar coil and straightens them, identifies the length and cuts the steel bars according to the predetermined length, and then transports them to the automatic steel mesh processing machine; S2: The automatic steel mesh processing machine moves longitudinally, and with the help of a robotic arm and a frame, it places linear longitudinal steel bars of different diameters and lengths in sequence, and then ties and welds them with transverse steel bars to complete the flat steel mesh; S3: The mesh moves forward along the conveyor mechanism to the bending processing area, where the bending equipment bends the mesh in one go to form an outer U-shaped mesh. S4: The outer U-shaped mesh is transported to the steel frame assembly area by mechanical equipment. After the prestressed pipes N1 and N2 are placed to the set position by mechanical equipment, the positioning is rechecked and fixed, and the bottom plate mesh frame steel bars and web mesh frame steel bars are installed; S5: Repeat the above-mentioned steel bar placement and binding operations, and bend the inner U-shaped mesh at one time; S6: transport the inner U-shaped mesh and the outer U-shaped mesh to assemble and form a double-layer U-shaped mesh structure; S7: Walk along the longitudinal direction and manually install the U-shaped tie bars at the corners of the bottom web and the positioning bars of the prestressed pipes at the web and tie them together; S8: Use mechanical equipment to place the prestressed pipes N3 and N4 to the predetermined position, and conduct positioning re-inspection and fixation; S9: Manually complete the installation and binding of the end prestressed pipe reinforcement spiral steel bars and anchor pads, and conduct a safety inspection of the steel mesh at the same time; S10: Repeat the above-mentioned steel bar placement and binding operations, and perform one-time bending to form the top plate lower mesh and the top plate upper mesh; S11: Hoist the inner formwork of the prefabricated box girder, use mechanical equipment to hoist the lower layer mesh of the top plate to the top of the inner formwork of the prefabricated box girder, tie the lower layer mesh of the top plate to the outer layer U-shaped mesh of the bottom web extending to the top plate, and the inner layer U-shaped mesh above the lower layer mesh of the top plate, and install the roof mesh frame steel bars; S12: Repeat the above steps to complete the lifting and installation of the upper mesh of the top plate, manually install and fix the inverted U-shaped steel bars at the top web nodes and check whether the entire steel frame is installed in place, thus completing the construction of the prefabricated box girder steel frame.

[0012] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art: 1. The present invention provides a method for forming a prefabricated box girder reinforcement skeleton suitable for factory manufacturing. This method meets the specification requirement that the stirrups of bending-torsion members should be closed. Two types of U-shaped tie bars are used to close the four nodes of the box section, so that the steel mesh forming scheme meets the specification requirements and at the same time improves the integrity of the reinforcement skeleton. 2. The present invention uses large-diameter first reinforcing steel bars on the inner side of the U-shaped mesh of the bottom web at the corner nodes to reinforce the mesh in the longitudinal direction, improve the structural stress, and increase the size of the concrete chamfer at this location to prevent concrete adhesion and peeling due to too small a cross-sectional angle during the removal of the inner formwork. 3. The present invention optimizes the original steel bar arrangement at the axil node of the top web, eliminates the four oblique crossbars that are inconvenient for mechanized construction, and adds top web node reinforcement steel bars on the outside of the intersection of the bottom web outer layer U-shaped mesh, the bottom web inner layer U-shaped mesh and the top plate lower layer mesh, thereby strengthening the node stiffness and reducing the influence of stress concentration at the node. At the same time, the concrete broken line cantilever section is eliminated and replaced with a straight line variable cross-section form, which improves the stress performance of the cantilever root and increases construction convenience. 4. The present invention is suitable for automatic grasping multi-grabbing mechanical equipment, automatic binding and welding steel mesh processing machines, automatic bending machines, etc., which can meet the production and spatial movement of meshes of different sizes and structures, reduce manual labor intensity, reduce the impact of manual work on the quality of box girder steel bars, and ensure the construction quality of box girder; 5. The present invention provides a method for forming a prefabricated box girder steel frame suitable for factory manufacturing. With the idea of ​​"double U + top plate" forming and assembly, the box girder steel frame obtained by assembling existing closed ring hoops is improved to a structure of bottom web double U mesh + top plate double-layer mesh. Each steel mesh can be automatically produced by bending, binding and welding equipment at the same time. The mesh is moved to the steel frame assembly area by a special lifting device to form a box girder steel frame. At the same time, prestressed pipe bundles are installed. The automation level of box girder steel frame production is increased to more than 80%, and the production cycle of a single beam steel frame is shortened from the original 12 hours to less than 3 hours, effectively improving production efficiency and construction quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a process flow chart of the prefabricated box beam reinforcement skeleton forming process adapted for factory manufacturing according to the present invention; Figure 2 The numbering and location diagram of the prestressed pipes of the prefabricated box girder reinforcement skeleton of the present invention; Figure 3 It is a schematic cross-sectional plan view of the prefabricated box beam reinforcement skeleton of the present invention; Figure 4 It is a schematic cross-sectional perspective view of the prefabricated box girder reinforcement skeleton of the present invention; Figure 5 This is a schematic diagram of a plane split of the prefabricated box girder reinforcement skeleton of the present invention; In the figure: 1-outer U-shaped mesh, 2-bottom plate mesh frame steel bars, 3-inner U-shaped mesh, 31-first reinforcing steel bars, 4-U-shaped tie steel bars, 5-positioning steel bars, 6-web mesh frame steel bars, 7-top plate lower mesh, 71-second reinforcing steel bars, 8-top plate mesh frame steel bars, 9-top plate upper mesh, 10-inverted U-shaped steel bars, 11-prestressed pipe. DETAILED DESCRIPTION

[0014] like Figure 1 FIG. 1 is a flow chart of a prefabricated box beam reinforcement skeleton forming process adapted for factory manufacturing according to the present invention. The forming method comprises the following construction steps: Step 1: The automatic steel bar straightening machine extracts the steel bars from the steel bar coil and straightens them, identifies the length and cuts the steel bars according to the predetermined length, and then transports them to the automatic steel mesh processing machine; Step 2: The automatic steel mesh processing machine moves longitudinally, and with the help of a robotic arm and a frame, it places straight longitudinal steel bars of different diameters and lengths in sequence, and then ties and welds them with transverse steel bars to complete the flat steel mesh; Step 3: The mesh moves forward along the conveying mechanism to the bending processing area, where the bending equipment bends the mesh once to form an outer U-shaped mesh 1; Step 4: The outer U-shaped mesh 1 is transported by mechanical equipment to the steel frame assembly area, and the prestressed pipes 11 N1 and N2 are placed in the set position by mechanical equipment, and then the positioning is rechecked and fixed, and the bottom plate mesh frame steel bars 2 and the web mesh frame steel bars 6 are installed; Step 5: Repeat the above-mentioned steel bar placement and binding operations, and bend the inner U-shaped mesh 3 at one time; Step 6: transport the inner U-shaped mesh 3 and the outer U-shaped mesh 1 to assemble and form a double-layer U-shaped mesh structure; Step 7: Walk along the longitudinal direction and manually install the U-shaped tie steel bars 4 at the corners of the bottom web and the positioning steel bars 5 of the prestressed pipe at the web and tie them together; Step 8: Use mechanical equipment to place the prestressed pipes 11 N3 and N4 to the predetermined position, and perform positioning recheck and fixation; Step 9: Manually complete the installation and binding of the end prestressed pipe 11 reinforcement spiral steel bars and anchor pads, and at the same time conduct a safety inspection of the steel mesh. The prestressed pipe number and location are as follows: Figure 2 As shown; Step 10: Repeat the above-mentioned steel bar placement and binding operations, and perform one-time bending to form the top plate lower mesh 7 and the top plate upper mesh 9; Step 11: Hoist the prefabricated box girder inner formwork, use mechanical equipment to hoist the top plate lower mesh 7 to the top of the prefabricated box girder inner formwork, tie the top plate lower mesh 7 and the bottom web outer layer U-shaped mesh 1 and inner layer U-shaped mesh 3 extending to the top plate and fix them above the top plate lower mesh 7, and install the top plate mesh frame steel bars 8; Step 12: Repeat the above steps to complete the lifting and installation of the upper mesh 9 of the top plate, manually install and fix the top web node inverted U-shaped steel bars 10 and check whether the entire steel skeleton is installed in place to complete the construction of the prefabricated box girder steel skeleton.

[0015] like Figure 3 and Figure 4 As shown, it is a cross-sectional plan view and a three-dimensional view of the prefabricated box girder reinforcement skeleton of the present invention. The prefabricated box girder reinforcement skeleton is divided into a double U+top plate mesh structure. The main body is composed of a bottom web outer U-shaped mesh 1, an inner U-shaped mesh 3, a top plate lower mesh 7, and a top plate upper mesh 9. Through sequential assembly and with the help of the bottom plate mesh frame steel bars 2, the bottom web corners are reinforced with the first reinforcing steel bars 31, the bottom web corners are reinforced with U-shaped tie bars 4, the web prestressed pipe positioning steel bars 5, the web mesh frame steel bars 6, the outer side of the intersection of the inner U-shaped mesh 3 and the top plate lower mesh 7 is reinforced with a second reinforcing steel bar 71, the second reinforcing steel bar 71 and the top plate mesh frame steel bars 8, and the inverted U-shaped steel bars 10 at the web nodes form a complete box girder reinforcement skeleton.

[0016] The lower mesh 7 and the upper mesh 9 of the prefabricated box girder top plate are formed by placing longitudinal and transverse steel bars in sequence and automatically binding and welding them by robots to form a flat mesh. The two long sides are bent by an automatic bending machine and assembled with the top plate mesh frame steel bars 8 to form a double-layer equivalent closed mesh steel bar skeleton of the top plate.

[0017] like Figure 5 As shown, it is a schematic diagram of the plane decomposition of the prefabricated box girder steel frame of the present invention. The outer U-shaped mesh 1 and the inner U-shaped mesh 3 are assembled in sequence and with the help of the bottom plate mesh frame steel bars 2, the first reinforcing steel bar 31 of the bottom web, the U-shaped tie steel bars 4 at the corners of the bottom web, the positioning steel bars 5 of the web prestressed pipe and the web mesh frame steel bars 6 form a double-layer U-shaped mesh structure of the bottom web, the first reinforcing steel bar 31 is placed on the inner side of the web inner U-shaped mesh 3, and the U-shaped tie steel bars 4 at the corners of the bottom web pass through the outer U-shaped mesh 1 of the bottom web and the inner U-shaped mesh 3 of the bottom web from the inside to the outside and are fixed.

[0018] The outer U-shaped mesh 1 and the inner U-shaped mesh 3 are connected to the upper mesh 9 of the top plate, the lower mesh 7 of the top plate, and the inverted U-shaped steel bars 10 at the web node by binding or welding to form a top web steel bar skeleton node. The outer U-shaped mesh 1 and the inner U-shaped mesh 3 extend out of the outer contour of the concrete.

Claims

1. A method for forming a prefabricated box beam reinforcement frame suitable for factory manufacturing, characterized in that: The prefabricated box girder reinforcement skeleton is divided into a double U+top plate mesh structure, the main body of which is composed of the outer U-shaped mesh of the bottom web (1), the inner U-shaped mesh (3), the lower mesh of the top plate (7), and the upper mesh of the top plate (9). By sequential assembly and with the help of the bottom plate mesh frame reinforcement (2), the bottom web corners are reinforced with the first reinforcing steel bar (31), the U-shaped tie steel bar (4) at the bottom web corners, the web prestressed pipe positioning steel bar (5), the web mesh frame reinforcement (6), the inner U-shaped mesh (3) and the lower mesh of the top plate (7) are reinforced with the second reinforcing steel bar (71) at the outer side of the intersection, the second reinforcing steel bar (71) and the top plate mesh frame reinforcement (8), and the inverted U-shaped steel bar (10) at the web node form a complete box girder reinforcement skeleton.

2. A method for forming a prefabricated box beam reinforcement skeleton suitable for factory manufacturing according to claim 1, characterized in that: The lower mesh (7) and the upper mesh (9) of the prefabricated box girder top plate are formed by sequentially placing longitudinal and transverse steel bars and automatically binding and welding them using a robot to form a flat mesh, and the two long sides are bent by an automatic bending machine and assembled with the top plate mesh frame steel bars (8) to form a double-layer equivalent closed mesh steel bar skeleton of the top plate.

3. The method for forming a prefabricated box beam reinforcement frame suitable for factory manufacturing according to claim 1, characterized in that: The outer U-shaped mesh (1) and the inner U-shaped mesh (3) are assembled in sequence and formed into a bottom web double-layer U-shaped mesh structure with the help of the bottom web mesh frame steel bars (2), the bottom web first reinforcement steel bars (31), the bottom web corner U-shaped tie steel bars (4), the web prestressed pipe positioning steel bars (5) and the web mesh frame steel bars (6).

4. The method for forming a prefabricated box beam reinforcement frame suitable for factory manufacturing according to claim 1, characterized in that: The first reinforcing steel bar (31) is placed inside the inner U-shaped mesh (3) of the web, and the U-shaped tie steel bar (4) at the corner of the bottom web passes through the outer U-shaped mesh (1) of the bottom web from the inside to the outside, and the inner U-shaped mesh (3) of the bottom web is fixed.

5. The method for forming a prefabricated box beam reinforcement frame suitable for factory manufacturing according to claim 1, characterized in that: The outer U-shaped mesh (1) and the inner U-shaped mesh (3) are connected to the top plate upper mesh (9), the top plate lower mesh (7), and the web node inverted U-shaped steel bars (10) by binding or welding to form a top web steel bar skeleton node. The outer U-shaped mesh (1) and the inner U-shaped mesh (3) extend beyond the outer contour of the concrete.

6. The method for forming a prefabricated box beam reinforcement frame suitable for factory manufacturing according to claim 1, characterized in that: The molding method includes the following construction steps: S1: The automatic steel bar straightening machine extracts the steel bars from the steel bar coil and straightens them, identifies the length and cuts the steel bars according to the predetermined length, and then transports them to the automatic steel mesh processing machine; S2: The automatic steel mesh processing machine moves longitudinally, and with the help of a robotic arm and a frame, it places linear longitudinal steel bars of different diameters and lengths in sequence, and then ties and welds them with transverse steel bars to complete the flat steel mesh; S3: The mesh moves forward along the conveying mechanism to the bending processing area, where the bending equipment bends the mesh in one go to form an outer U-shaped mesh (1); S4: The outer U-shaped mesh (1) is transported to the steel frame assembly area by mechanical equipment, and the prestressed pipes (11) N1 and N2 are placed at the set position by mechanical equipment, and then the positioning is rechecked and fixed, and the bottom plate mesh frame steel bars (2) and the web plate mesh frame steel bars (6) are installed; S5: Repeat the above-mentioned steel bar placement and binding operations, and bend the inner U-shaped mesh (3) at one time; S6: transporting the inner U-shaped mesh (3) and the outer U-shaped mesh (1) to assemble them to form a double-layer U-shaped mesh structure; S7: walking along the longitudinal direction and manually installing the U-shaped tie bars (4) at the corners of the bottom web and the positioning bars (5) of the prestressed pipe at the web and tying them up; S8: Use mechanical equipment to place the prestressed pipes (11) N3 and N4 to the predetermined position, and conduct positioning recheck and fixation; S9: Manually complete the installation and binding of the end prestressed pipe (11) reinforcement spiral steel bars and anchor pads, and conduct a safety inspection of the steel mesh at the same time; S10: Repeat the above-mentioned steel bar placement and binding operations, and perform one-time bending to form the top plate lower mesh (7) and the top plate upper mesh (9); S11: hoisting the inner formwork of the prefabricated box beam, hoisting the lower mesh of the top plate (7) to the upper part of the inner formwork of the prefabricated box beam by mechanical equipment, tying the lower mesh of the top plate (7) and the outer U-shaped mesh of the bottom web (1) and the inner U-shaped mesh (3) extending to the top plate to fix them above the lower mesh of the top plate (7), and installing the top plate mesh frame steel bars (8); S12: Repeat the above steps to complete the lifting and installation of the upper mesh of the top plate (9), manually install and fix the top web node inverted U-shaped steel bars (10) and check whether the entire steel frame is installed in place, thus completing the construction of the prefabricated box girder steel frame.

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