An inclined bracket stay cable anchoring combined structure and a construction method thereof

Abstract

The present application belongs to the field of bridge engineering, and particularly relates to a kind of oblique bracket inclined cable anchoring combination structure and its construction method, mainly used for short tower cable-stayed reinforced PSC continuous box girder bridge.The structure includes concrete box girder, prestressed finish rolling threaded steel bar, bracket support, cable anchoring device.By punching through the reinforcement through hole in the old bridge concrete box girder, the prestressed reinforcement is penetrated in the concrete box girder, the bracket support cable anchoring combination structure can be erected outside the web plate of the box girder, which realizes the stable connection of the cable anchoring place of the short tower cable-stayed system reinforced PSC continuous box girder bridge and the rapid erection of the construction platform.Using the weldable assembly oblique bracket support component, the cable anchoring pipe is installed at the oblique web member, so that the load borne by the main girder can be transferred to the cable, thereby effectively relieving the load borne by the main girder.

Description

Technical Field

[0001] This invention belongs to the field of prestressed concrete continuous box girder bridge renovation and reinforcement technology, and specifically relates to an inclined bracket cable anchorage combination structure for reinforcing prestressed concrete continuous box girder bridges with low towers and its construction method. Background Technology

[0002] The low-tower cable-stayed reinforcement method uses a low-tower cable-stayed system to strengthen large-span PSC continuous box girder bridges. It provides additional elastic support to the structure with minimal alteration to the original bridge structure, and its applicable span range is consistent with that of PSC continuous box girder bridges. It effectively improves the stress mechanism of continuous beam bridges. On one hand, the vertical component of the stay cables bears the dead load of the original structure, achieving deformation recovery; on the other hand, the horizontal component of the stay cables improves the axial pressure on the main girder. While the low-tower cable-stayed reinforcement method has a limited application scope due to insufficient theoretical research and a lack of systematic design and construction studies, its application prospects and benefits are broad.

[0003] The stay cables are anchored to the side span main beams and the middle span main beams. They can be anchored to newly added toothed plates inside the box girder or to structures added to the lower edge of the box girder bottom plate. However, this still results in too many anchoring points and complex construction, and can easily cause excessive damage to the existing bridge during construction. Traditional corbel steel brackets are widely used in various fields, but require a large number of embedded parts to ensure the stability of the corbel components. They are generally suitable for temporary structures and cannot guarantee the long-term use of structural components. Since traditional embedded parts are generally fixed to the corbel steel brackets by welding, the connection strength is low and the construction risk is high. Shear failure is prone to occur at the weld joints, which significantly reduces the load-bearing capacity. Summary of the Invention

[0004] This invention provides a combined structure for inclined corbel cable anchorage and its construction method for reinforcing PSC continuous box girder bridges with low-tower cable-stayed systems. This invention effectively avoids the complex technical problems associated with cable anchorage points in PSC continuous box girder bridges reinforced with low-tower cable-stayed systems. It also improves the stress performance of the original continuous box girder, alleviating excessive mid-span deflection and large cracking areas in the original concrete box girder. Compared to traditional cable anchorage structures, this anchorage structure can be installed on a permanent corbel support frame, enabling rapid construction and installation of the anchorage device. The corbel support component can be quickly installed on the box girder, allowing the box girder and corbel component to share the load, with effective and stable connection provided by precision-rolled threaded steel bars. The overall construction process is simple and efficient, significantly improving the original continuous beam bridge, ensuring reliable connection strength between components, and minimizing damage to the original old bridge, thus realizing rapid continuous beam bridge renovation projects.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] An inclined corbel cable-stayed composite structure, comprising a concrete box girder, a prestressed system, a corbel support frame structure, and a cable-stayed anchorage structure;

[0007] Before reinforcement, the concrete box girder acted on the supports, which transferred the load of the main girder. The supports were placed at the piers, the piers acted on the foundation, and the foundation acted on the ground. The above combination formed the original continuous box girder bridge.

[0008] The prestressed system includes prestressing tendons, tie rod through holes, anchor bolts, shear pins, pin embedded parts, pads, bearing plate supports, bearing plates, and concrete cover. During reinforcement, mechanical methods are used to pre-drill tie rod through holes at appropriate locations on the concrete box girder, embed the pin embedded parts and shear pins, and weld the pads, bearing plate supports, and bearing plates together to allow the prestressing tendons to penetrate the concrete box girder, and then anchor them with anchor bolts.

[0009] The corbel support frame structure includes an upper chord, diagonal uprights, diagonal connecting rods, diagonal support rods, diagonal web members, vertical stiffening ribs, reinforcing connectors, and anchor stiffening plates. The upper chord, diagonal uprights, diagonal connecting rods, diagonal support rods, and diagonal web members are prefabricated in the factory. They are then transported to the site where the various members are welded together and locally reinforced using vertical stiffening ribs, reinforcing connectors, and anchor stiffening plates.

[0010] The cable anchoring structure includes a cable anchor head, a cable anchor block, a cable anchor pipe, a cable guide pipe, and a stay cable; the stay cable is passed through the cable guide pipe and the cable anchor pipe, and anchored on the cable anchor block by the cable anchor head.

[0011] Furthermore, the prestressed tendons are tensioned to fix the upper chord, diagonal uprights, and diagonal support rods to the outside of the web of the concrete box girder, thereby integrating the corbel support frame structure with the concrete box girder. The corbel support frame structure forms a stable connection between the concrete box girder and the cable anchoring structure, allowing the cable-beam structure to share the load.

[0012] A construction method for an inclined corbel cable-stayed composite structure, based on the inclined corbel cable-stayed composite structure described above, includes the following steps:

[0013] 1) Based on the original data and monitoring data of the old bridge, assess the bridge's hazardous condition and load-bearing capacity, formulate a reinforcement plan for the low tower cable-stayed system, design the dimensions, quantity and layout of each component, and determine the specific renovation construction and monitoring plan.

[0014] 2) According to the design plan, avoiding the steel reinforcement, use precision instruments to drill through holes for the tie bars at the designed locations, and erect a construction platform at the bottom of the concrete box girder;

[0015] 3) The factory prefabricates each component according to the design requirements, transports them to the site for installation, tensions and anchors the prestressed tendons through the ducts, and wraps them with a concrete protective layer.

[0016] 4) Weld all the bracket components together on site, and reserve holes at the top chord to facilitate the placement of stay cables and anchoring components. Use stiffening plates to weld the components together for connection and reinforcement.

[0017] 5) Hoist the corbel support components at the working platform and install them on both sides of the web of the concrete box girder. Place the stay cables in the cable guide pipes, anchor the stay cables with cable anchor heads, and tension them at the bottom of the beam.

[0018] The construction method of the inclined bracket cable anchorage combination structure described above is applied to a standard three-span, single-box, single-cell PSC continuous box girder bridge.

[0019] The construction method of the inclined corbel cable-stayed bridge anchorage combination structure described above is applied to T-shaped, three-span, and multi-span bridge types, as well as PSC continuous box girder bridges with various structures such as single-box double-cell, single-box triple-cell, and single-box multi-cell combinations.

[0020] This invention has at least the following technical effects:

[0021] This invention transfers the load borne by the main beam to the cables by installing weldable and assembly-compatible inclined corbel support components on both sides of the concrete box girder. This effectively alleviates the load on the main beam, improves the bending and shear resistance of the concrete box girder, and effectively slows down crack development and mid-span deflection.

[0022] This invention avoids the problem of excessive damage to the original old bridge caused by the construction of cable-stayed bridge anchorages. It is beneficial to use the corbel composite components to erect the construction platform, and realizes the rapid construction and renovation of the original PSC continuous beam bridge by using the low tower cable-stayed reinforcement method. This allows the main beam, cables and bridge towers to share the load, effectively improve the defects and improve the load-bearing capacity of the original PSC continuous beam bridge.

[0023] This invention has a wide range of applications. All components are prefabricated in the factory, ensuring the processing accuracy of the components and effectively shortening the renovation period of the reinforcement factory. In addition, all steel components are rust-proofed in the factory, and the use of prestressed tendons makes the corbel anchorage combination structure form a stable and reliable connection on both sides of the box girder, ensuring the long-term performance of the corbel anchorage combination structure. Attached Figure Description

[0024] In drawings that are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. The same reference numerals with or without letter suffixes may indicate different instances of similar parts. The drawings generally illustrate various embodiments by way of example rather than limitation and, together with the description and claims, serve to explain embodiments of the invention. Where appropriate, the same reference numerals are used in all drawings to refer to the same or similar parts. Such embodiments are illustrative and not intended to be exhaustive or exclusive embodiments of the apparatus or method.

[0025] Figure 1 3D model of the reinforced front box girder;

[0026] Figure 2 This is an overall rendering of the reinforced structure.

[0027] Figure 3 3D model of the reinforced box girder;

[0028] Figure 4 Cross-sectional view of the reinforced rear box girder;

[0029] Figure 5 Side view of the reinforced box girder;

[0030] Figure 6 This is a structural diagram of prestressed tendons;

[0031] Figure 7 This is a structural diagram of the tie rod anchoring device;

[0032] Figure 8 Diagram of the corbel support structure;

[0033] Figure 9 Construction diagram of the connecting support frame;

[0034] Figure 10 This is a structural diagram of the cable-stayed bridge anchorage component.

[0035] Among them, concrete box girder-1, prestressed tendon-2, tie rod through hole-3, anchor bolt-4, shear pin-5, pin embedded part-6, pad plate-7, bearing plate support-8, bearing plate-9, top chord-10, diagonal upright-11, diagonal connector-12, diagonal support rod-13, diagonal web member-14, vertical stiffening rib-15, reinforcing connector-16, anchor stiffening plate-17, cable anchor head-18, cable anchor block-19, cable anchor pipe-20, cable guide pipe-21, diagonal cable-22, stabilizing connection support-23, diagonal connecting rod-24, concrete protective layer-25, tower column-26, support-27, pier column-28. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and specific examples, but this is not intended to limit the present invention. If there is no necessary sequential relationship between the various steps described herein, the order in which they are described as examples should not be considered a limitation. Those skilled in the art should understand that the order can be adjusted, as long as it does not disrupt the logical consistency between them and render the entire process impossible.

[0037] Reference Figure 1-10 As shown, this embodiment provides an inclined corbel cable anchorage combination structure, which includes a concrete box girder, a prestressed system, a corbel support frame structure, a cable anchorage structure, and inclined cables.

[0038] Before reinforcement, the concrete box girder 1 acts on the support 27, and the support 27 transmits the load of the main girder. The support 27 is placed at the pier 28, the pier 28 acts on the foundation, and the foundation acts on the ground. The above combination forms the original continuous box girder bridge.

[0039] The prestressed system includes prestressing tendons 2, tie rod through holes 3, anchor bolts 4, shear pins 5, pin embedded parts 6, pads 7, bearing plate supports 8, bearing plates 9, and a concrete protective layer 25. During reinforcement, tie rod through holes 3 are pre-drilled at the designed locations on the concrete box girder 1 using machinery, and the pin embedded parts 6 are installed. The pads 7, bearing plate supports 8, and bearing plates 9 are welded together. The welded steel plates are fixed to the web of the box girder by driving in shear pins 5. The prestressing tendons 2 can penetrate the concrete box girder 1, and the prestressing tendons 2 are tensioned on the construction platform. The prestressing tendons 1 are anchored using anchor bolts 4, allowing the corbel support structures on both sides to form a stable connection on the outside of the box girder.

[0040] The bracket support structure includes an upper chord 10, diagonal uprights 11, diagonal connecting rods 12, diagonal support rods 13, diagonal web members 14, vertical stiffening ribs 15, reinforcing connectors 16, and anchor stiffening plates 17. According to design requirements, the upper chord 10, diagonal uprights 11, diagonal connecting rods 12, diagonal support rods 13, and diagonal web members 14 are prefabricated in the factory; they are then transported to the site where they are welded together, and locally reinforced using vertical stiffening ribs 15 and reinforcing connectors 16. Simultaneously, operating space is reserved at the position of the upper chord 10 for the cable guide tube 21 and cable anchor tube 20 to facilitate the subsequent tensioning and anchoring of the stay cables 22.

[0041] The cable anchoring structure includes a cable anchor head 18, a cable anchor block 19, a cable anchor pipe 20, a cable guide pipe 21, and a cable 22. An anchor plate is installed at the end of the upper chord 10 corresponding to the end of the cable. A slot is opened at the upper end of the anchor plate to meet the space requirements for the installation of the anchor at the end of the cable 22. The anchor pipe 20 is welded into the slot, and the cable passes through the anchor pipe 20 and is anchored to the bottom of the anchor pipe by the anchor 19. Stiffening plates 17 are provided on both sides of the anchor plate structure and welded to the upper chord 10 to enhance the overall rigidity of the component.

[0042] The reinforcement principle of the inclined bracket cable anchorage combination structure:

[0043] The concrete box girder 1 and the stay cables 22 are anchored together by prestressed tendons 2, corbel support members, and cable anchoring devices. The prestressed tendons 2 provide horizontal tension to the corbel support members and play a role in lateral stability. The concrete box girder 1 transfers the upper load to the corbel connector, which then transfers the load to the corbel support members. The vertical force is then shared by the diagonal support rods and transferred to the main tower along the stay cables 22.

[0044] The inclined corbel allows the vertical component of the load to be transferred to the stay cable 22, and the lateral component to the box girder 1. The main tower bears the vertical component, while the movable support bears the lateral component. This anchorage combination structure allows the cable, girder, and tower to share the load, improving the stress state of the main girder, increasing its load-bearing capacity, and alleviating defects.

[0045] Based on the inclined corbel cable anchorage combination structure described above, this invention provides a construction method for the inclined corbel cable anchorage combination structure, the main construction method of which is as follows:

[0046] A construction platform is installed at the bottom of the concrete box girder 1, and mechanical drilling is used to drill through holes 3 for the tie bars at the designed locations to install the pin embedded parts. The bearing plate 9 assembly is installed at the hole location, shear pins are driven in to fix the bearing plate 9 assembly, and the prestressed tendons 2 are passed through for tensioning and anchoring, and an outer concrete protective layer 25 is wrapped to ensure that the corbel support members can form a stable connection on both sides of the web of the box girder 1.

[0047] According to the design requirements, all bracket support components were prefabricated in the factory and transported to the site for welding and assembly. Cable anchor pipes 21 were pre-installed at the diagonal web members 14 to facilitate cable installation and anchoring. Vertical stiffening ribs 15 and reinforcing connectors 16 were welded at locations with high stress to reinforce the connections of the bracket components. The stay cables 22 at the beam ends were installed using a winch and anchored with cable anchor heads 18. The stay cables were then tensioned at the bottom of the beam. Finally, all steel components underwent rust prevention treatment, and the construction platform was removed.

[0048] Therefore, this invention provides an inclined corbel cable-stayed bridge anchorage combination structure and its construction method, mainly used for reinforcing PSC continuous beam bridges using a cable-stayed system. The specific reinforcement effect is as follows: Figure 3 As shown, it includes concrete box girders ( Figure 1 ), prestressed tendons ( Figure 6 ), tie rod anchoring device ( Figure 7 ), cow leg support ( Figure 8 ), connecting support ( Figure 9 ) and cable anchoring devices ( Figure 10 ).

[0049] Prestressing tendons are inserted through holes drilled on the outside of the concrete box girder, and tie rod anchoring devices are installed. A construction platform is erected to tension and anchor the prestressing and pour a concrete protective layer, ensuring a stable connection between the corbel supports on both sides of the box girder. Corbel support components and connecting support components are prefabricated and assembled in the factory, installed and welded to both sides of the box girder, and pre-drilled holes for stay cables. The stay cable anchoring devices are installed inside the upper chord, and finally, tensioning and anchoring are performed.

[0050] This invention employs a cable-stayed system to reinforce PSC continuous beam bridges, transferring vertical loads to the cable stays while longitudinal loads are borne by movable supports. The stress distribution of this invention is explained below:

[0051] Taking a moment for the connection node between the upper chord and the side of the box girder, such that the maximum downward static friction force is greater than the cable force transmitted by the stay cable, the bracket size setting relationship should conform to the following formula:

[0052]

[0053] In the formula:

[0054] L is the horizontal distance from the cable tension of the stay cable to the connection point between the upper chord and the side of the box girder;

[0055] H is the oblique distance between the two connection points between the upper and lower chords and the side of the box girder;

[0056] μ is the static friction coefficient between the pad and the concrete.

[0057] The arrangement of prestressed steel bars should conform to the following formula:

[0058]

[0059] In the formula:

[0060] n is the number of prestressed tendons.

[0061] fpd is the tensile design strength of the prestressed tendon.

[0062] Ap is the cross-sectional area of ​​a single prestressed tendon.

[0063] T represents the oblique component of the cable force and the self-weight of the steel structure.

[0064] The construction method for an inclined bracket cable-stayed composite structure using the above design includes the following specific construction steps:

[0065] 1) Based on the original design data and monitoring data, determine the bridge damage status and existing load-bearing capacity, formulate a short tower cable-stayed reinforcement scheme, design the dimensions, quantity and layout of each component, and determine the reinforcement and renovation construction and monitoring scheme.

[0066] 2) According to the design plan, construct a construction platform at the bottom of the beam, avoiding the steel bars and prestressing tendons. Use precision instruments to drill through holes for the tie bars at the designed locations, pre-embed pins, drive in shear pins, and then... Figure 7 The tie rod anchoring device shown is installed on both sides.

[0067] 3) Prefabricate all bracket components in the factory, transport them to the site for installation, pass the prestressed tendons through the ducts for tensioning and anchoring, and wrap them externally as shown. Figure 6 The concrete protective layer shown.

[0068] 4) Weld all the corbel components and connecting support components together on site, hoist them to the anchoring position of the tie rod, and reserve a hole at the end of the upper chord to facilitate the placement of the cable anchoring device. Use the corbel support components to build a tensioning construction platform and use stiffening plates for welding reinforcement.

[0069] 5) Install the stay cable anchor pipe and guide pipe at the reserved position on the upper chord, and pass the stay cable through the anchor pipe. Use a winch to install the stay cable, tension it at the bottom, and anchor it with the cable anchor head. Weld the connection parts, such as... Figure 10 As shown. During the tensioning process, pay attention to monitoring changes in cable tension and stress in the steel components.

[0070] 6) Permanent anti-corrosion and anti-rust treatment was carried out on all steel components, the construction platform was removed, and the entire reinforcement and renovation project was completed.

[0071] Furthermore, although exemplary embodiments have been described herein, their scope includes any and all embodiments based on the invention that have equivalent elements, modifications, omissions, combinations, such as various overlapping embodiments, adaptations, or alterations. Elements in the claims will be interpreted broadly based on the language used in the claims and are not limited to the examples described in this specification or during the implementation of this application, and such examples will be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered illustrative only, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0072] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more of them) can be used in combination with each other. Other embodiments can be used by those skilled in the art when reading the above description. Furthermore, in the above detailed description, various features may be grouped together to simplify the invention. This should not be construed as an intention that a feature of an unclaimed invention is necessary for any claim. Rather, the subject matter of the invention may be less than all the features of a particular embodiment of the invention. Thus, the following claims are incorporated herein by reference as examples or embodiments, wherein each claim is an independent, separate embodiment, and these embodiments are contemplated to be combined with each other in various combinations or arrangements. The scope of the invention should be determined by reference to the appended claims and the full scope of their equivalents.

Claims

1. A type of inclined bracket cable anchorage combination structure, characterized in that: The structure includes a concrete box girder, a prestressed system, a corbel support frame structure, and a cable anchorage structure. Before reinforcement, the concrete box girder (1) acts on the support (27), and the support transfers the main beam load. The support is placed at the pier (28), the pier (28) acts on the foundation, and the foundation acts on the ground, forming the original continuous box girder bridge. The prestressed system includes prestressed tendons (2), tie rod through holes (3), anchor bolts (4), shear pins (5), pin embedded parts (6), pads (7), bearing plate supports (8), bearing plates (9), and concrete protective layers (25). During reinforcement, tie rod through holes (3) are pre-drilled at appropriate positions in the concrete box girder (1) using machinery, and pin embedded parts (6) and shear pins (5) are installed. The pads (7), bearing plate supports (8), and bearing plates (9) are welded together so that the prestressed tendons (2) can penetrate the concrete box girder (1) and be anchored with anchor bolts (4). The corbel support frame structure includes an upper chord (10), diagonal uprights (11), diagonal connecting rods (12), diagonal support rods (13), diagonal web members (14), vertical stiffening ribs (15), reinforcing connectors (16), and anchor stiffening plates (17). The upper chord (10), diagonal uprights (11), diagonal connecting rods (12), diagonal support rods (13), and diagonal web members (14) are prefabricated in the factory. They are then transported to the site where the members are welded together and locally reinforced using vertical stiffening ribs (15), reinforcing connectors (16), and anchor stiffening plates (17). The cable anchoring structure includes a cable anchor head (18), a cable anchor block (19), a cable anchor pipe (20), a cable guide pipe (21), and a stay cable (22); the stay cable (22) is passed through the cable guide pipe (21) and the cable anchor pipe (20), and anchored on the cable anchor block (19) with the cable anchor head (18); The prestressed tendons (2) are tensioned to fix the upper chord (10), the inclined uprights (11), and the inclined support rods (13) to the outside of the web of the concrete box girder (1), so as to form the corbel support frame structure with the concrete box girder (1) as a whole; the corbel support frame structure forms a stable connection between the concrete box girder (1) and the cable anchoring structure, so that the cable-beam structure is subjected to the same force.

2. A construction method for an inclined corbel cable-stayed composite structure, characterized in that: Based on the inclined bracket cable anchorage combination structure as described in claim 1, the construction method includes the following steps: 1) Based on the existing data and monitoring data of the old bridge, assess the bridge's hazardous condition and load-bearing capacity, formulate a reinforcement plan for the low-tower cable-stayed system, design the dimensions, quantity and layout of each component, and determine the specific renovation construction and monitoring plan; 2) According to the design plan, avoid the steel reinforcement and use precision instruments to drill through holes for the tie bars at the design location (3), and erect a construction platform at the bottom of the concrete box girder (1); 3) The factory prefabricates each component according to the design requirements, transports them to the site for installation, tensions and anchors the prestressed tendons (2) through the tie rod through holes (3), and wraps them with a concrete protective layer (25). 4) Weld the bracket components together on site and reserve holes at the upper chord to facilitate the placement of the stay cable (22) and cable anchor block (19). Use stiffening plates to weld the components together for connection and reinforcement. 5) Hoist the corbel support components at the working platform and install them on both sides of the web of the concrete box girder (1). Place the stay cables in the cable guide (21), anchor the stay cables (22) with the cable anchor head (18), and tension them at the bottom of the beam.

3. The construction method of the inclined corbel cable anchorage combination structure according to claim 2 is applied to a standard three-span PSC continuous box girder bridge with a single box and single cell.

4. The construction method of the inclined corbel cable-stayed composite structure according to claim 2 is applicable to T-shaped, three-span, and multi-span bridge span types, as well as PSC continuous box girder bridges with various structures composed of single-box double-cell, single-box triple-cell, and single-box multi-cell combinations.

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