A cable-beam anchoring structure for strengthening a cable-stayed system and a construction method thereof

Abstract

The present invention discloses a cable-beam anchoring structure for reinforcing a cable-stayed system and a construction method thereof. The structure includes a bridge tower, a cable and a composite steel section, and a corbel welded to the composite steel section. The structure anchors the composite steel section to the top plate of the box beam through a connecting device, the bridge tower is welded to the composite steel section, and the bridge tower and the composite steel section are connected by cables. The present invention makes full use of the good tensile properties of steel, so that the horizontal component of force generated by the cable is borne by the shearing force of the first corbel, which can directly avoid the adverse effect of large axial tension on the main beam in the cable-free area in the middle span of a traditional cable-stayed bridge, while the vertical force can provide an upward lifting force to the main beam, thereby enhancing the bending and shearing resistance of the main beam, reducing the downward deflection deformation of the main beam, and inhibiting the development of cracks in the main beam. The present invention has a simple structure, convenient construction, safety and economy, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of repairing and reinforcing prestressed concrete continuous box girder bridges, and in particular relates to a cable-beam anchoring structure for reinforcing a cable-stayed system and a construction method thereof. Background Art

[0002] With the vigorous development of national infrastructure, the field of bridges has shown the characteristics of new systems, large numbers and large spans in recent decades, among which the large-span PSC continuous box girder bridge is the main bridge type. As the service time gets longer, there are more and more local cracks and deflections in the bridges. These situations will lead to the safety, durability and applicability of the bridges being restricted. The use of reasonable reinforcement methods can not only improve the bearing capacity of the bridge, but also save maintenance costs. The commonly used reinforcement methods are: increasing the cross-section method, thickening the bridge deck reinforcement layer method, anchor spraying concrete method, pasting steel plates method, pasting carbon fiber cloth method, changing the structural system method, external prestressing method, etc. The present invention belongs to the reinforcement method of changing the structural system. Summary of the Invention

[0003] The purpose of the present invention is to address the shortcomings of existing reinforcement methods and provide a cable-girder anchoring structure and a construction method for reinforcing a cable-stayed system. This method can improve the local cracking, mid-span deflection and other defects of PSC continuous box girder bridges, improve the bearing capacity of the bridge, and is suitable for the current situation of increasing traffic volume.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A cable-beam anchoring structure for reinforcing a cable-stayed system, comprising a box girder top plate, a composite steel section, a first corbel, a bridge tower, cables, a support, a pier, a foundation, a No. 0 block, vertical prestressed tendons, an upper horizontal steel plate, a vertical steel plate, a lower horizontal steel plate, anchor bolts, an extension device, a first borehole, a second borehole, an ear plate, a local reinforcement steel plate, a first cable anchor head, a third borehole, a second corbel, a second cable anchor head, a steel anchor beam, and a main beam;

[0006] The main beam of the original structure transmits force to the foundation through the bridge piers and the foundation, and the main beam, bridge piers and foundation form a continuous box beam bridge;

[0007] The first corbel is a hollow trapezoidal structure formed by welding steel plates; the combined steel is welded by an upper horizontal steel plate, a vertical steel plate, a lower horizontal steel plate, a first corbel, a lug plate, and a local reinforcement steel plate; the first drill hole and the second drill hole are respectively provided on the lower horizontal steel plate and the first corbel, and the vertical prestressed tendons are extended by the extension device; the combined steel and the box girder top plate are anchored together by extension bolts;

[0008] The bridge tower is composed of a second corbel and a steel anchor beam, and the bridge tower is welded to the composite steel; the horizontal component of the cable is borne by the steel anchor beam, and the vertical component of the cable is transmitted to the bridge tower by the second corbel; the cable is anchored to the composite steel and the bridge tower respectively through the first cable anchor head and the second cable anchor head.

[0009] A construction method for reinforcing a cable-stayed system, based on the cable-beam anchoring structure described above, comprises:

[0010] Step 1: Obtain the actual service performance of the bridge through field measurements. Determine the required load-bearing capacity of the pre-reinforced bridge based on construction requirements. Analyze and calculate the stresses on the pylons, cables, composite steel, and connection devices. This will determine the specific size, quantity, steel grade, and layout of the reinforcement components.

[0011] Step 2: Calculate the force of the cable through step 1 and determine the tensioning sequence and tensioning force of the cable;

[0012] Step 3: The processing plant will process the bridge towers, composite steel, and steel anchor beams, and drill holes in the corresponding locations according to the construction drawings. A groove is chiseled at the location of the vertical prestressed reinforcement on the centerline of the main beam top plate to expose the vertical prestressed reinforcement. The reinforcement is passed through the first bracket and connected with extension bolts to anchor the composite steel to the box beam top plate.

[0013] Step 4: Determine the position of the bridge tower relative to the composite steel, weld the processed bridge tower segments upward one by one, and reserve a cable tensioning construction platform at the corresponding position;

[0014] Step 5: Install pulleys and winches on the bridge tower to lift the cables. Pull the cables into the tower holes in sequence, pass them through the steel anchor beams, and anchor them with the second cable anchor head. Install the other end of the cables on the lugs and anchor them with the first cable anchor head.

[0015] Step 6: Tension the cables in sequence to the required tension;

[0016] Step 7: Drill a third hole at the place where the upper horizontal steel plate cable passes, splice and weld them; perform anti-corrosion and anti-rust treatment on all steel components, and the continuous beam bridge reinforcement is completed.

[0017] Furthermore, the tensile strength of the vertical prestressed tendons complies with the following formula:

[0018]

[0019] Where:

[0020] F is the cable tension;

[0021] e is the vertical distance from the cable anchoring position to the first drill hole;

[0022] d is the longitudinal spacing distance of the first borehole;

[0023] θ is the horizontal angle between the cable and the main beam top plate;

[0024] n is the number of vertical prestressing tendons in a segment;

[0025] γ1 is the safety factor;

[0026] A is the cross-sectional area of ​​the vertical prestressed tendons;

[0027] f is the tensile strength of the vertical prestressed tendons.

[0028] Furthermore, the welding strength of the first bracket and the combined steel conforms to the following formula:

[0029] N1+N2≥γ2Fcosθ

[0030] Where:

[0031] F is the cable tension;

[0032] N1 is the front fillet weld bearing capacity;

[0033] N2 is the side fillet weld bearing capacity;

[0034] γ2 is the safety factor

[0035] θ is the horizontal angle between the cable and the main beam top plate;

[0036] in,

[0037] β f The strength design value increase factor of the front fillet weld;

[0038] h e ,h e ' is the effective thickness of the fillet weld;

[0039] ∑l w ,∑l w ' is the sum of the calculated lengths of the fillet welds on one side of the connection;

[0040] Design strength value of fillet weld.

[0041] The construction method described above is applied to a standard three-span single-box double-chamber PSC continuous beam bridge.

[0042] According to the construction method described above, the bridge span types of double-span beams, three-span beams, and multi-span beams are combined with the box chamber types of single-box single-chamber, single-box double-chamber, single-box double-chamber, and multi-box multi-chamber to form PSC continuous box girder bridges of various structures.

[0043] The present invention has at least the following technical effects:

[0044] This invention fully utilizes the excellent tensile properties of steel, allowing the horizontal force component generated by the cables to be borne by the shear force of the first corbel. This directly avoids the adverse effects of high axial tension on the main beam in the cable-free mid-span area of ​​traditional cable-stayed bridges. The vertical force provides an upward lifting force on the main beam, enhancing its bending and shear resistance, reducing deflection, and inhibiting the development of cracks in the beam. This invention boasts a simple structure, convenient construction, safety, and economy, and has excellent application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar components in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar components. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the description and claims, serve to illustrate the embodiments of the invention. Where appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive of the embodiments of the present apparatus or method.

[0046] Figure 1 The longitudinal structural diagram of the PSC continuous box girder bridge for strengthening the first three spans;

[0047] Figure 2 This is the elevation drawing of the cable-stayed bridge after reinforcement;

[0048] Figure 3 This is the 1 / 2 elevation of the cable-stayed bridge after reinforcement;

[0049] Figure 4 This is the cross-sectional view of the reinforced front box beam;

[0050] Figure 5 This is the cross-section diagram of the box beam after reinforcement;

[0051] Figure 6 This is the longitudinal structural drawing of the composite steel segment;

[0052] Figure 7 It is a three-dimensional diagram of the combined steel segment;

[0053] Figure 8 This is the transverse arrangement diagram of the bridge tower.

[0054] In the figure: box girder top plate (1), combined steel (2), first bracket (3), bridge tower (4), cable (5), middle support (6), bridge pier (7), foundation (8), block No. 0 (9), vertical prestressed tendons (10), upper horizontal steel plate (11), vertical steel plate (12), lower horizontal steel plate (13), anchor bolts (14), extension device (15), first drill hole (16), second drill hole (17), ear plate (18), local reinforcement steel plate (19), first cable anchor head (20), third drill hole (21), second bracket (22), second cable anchor head (23), steel anchor cross beam (24), main beam (25). DETAILED DESCRIPTION

[0055] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments, but are not intended to limit the present invention. For the various steps described herein, if there is no necessity for a contextual relationship between each other, the order in which they are described as examples herein should not be regarded as limiting, and those skilled in the art should know that they can be adjusted in order as long as the logic between them is not destroyed, resulting in the inability to implement the entire process.

[0056] Reference Figure 1-8 As shown, this embodiment provides a cable-beam anchoring structure for reinforcing a cable-stayed system, which includes a box girder top plate 1, a composite steel 2, a first corbel 3, a bridge tower 4, a cable 5, a support 6, a pier 7, a foundation 8, a No. 0 block 9, a vertical prestressed tendon 10, an upper horizontal steel plate 11, a vertical steel plate 12, a lower horizontal steel plate 13, an anchor bolt 14, an extension device 15, a first drilled hole 16, a second drilled hole 17, an ear plate 18, a local reinforcement steel plate 19, a first cable anchor head 20, a third drilled hole 21, a second corbel 22, a second cable anchor head 23, a steel anchor beam 24, and a main beam 25.

[0057] Before reinforcement, the main beam 25 transmits force to the foundation through the piers 7 and the foundation 8, and the main beam 25, the piers 7 and the foundation 8 form a continuous box beam bridge.

[0058] The first corbel 3 is a hollow trapezoidal structure formed by welding steel plates; the combined steel 2 is welded by an upper horizontal steel plate 11, a vertical steel plate 12, a lower horizontal steel plate 13, the first corbel 3, an ear plate 18, and a local reinforcement steel plate 19; a first drill hole 16 and a second drill hole 17 are respectively drilled on the lower horizontal steel plate 13 and the first corbel 3 using a machine, and the vertical prestressed tendons 10 are extended by the extension device 15; and the combined steel 2 and the box girder top plate 1 are anchored together using extension bolts.

[0059] The bridge tower 4 is composed of a second corbel 22 and a steel anchor beam 24, which are welded to the composite steel 2; the horizontal component of the cable 5 is borne by the steel anchor beam 24, and the vertical component of the cable is transmitted to the bridge tower 4 by the second corbel 23; the cable 5 is anchored to the composite steel 2 and the bridge tower 4 respectively through the first cable anchor head 20 and the second cable anchor head 23.

[0060] Technical principle of cable-stayed system reinforcement: the box girder top plate 1 and the composite steel 2 are anchored together by the first corbel 3, the vertical prestressed tendons 10 and the extension device 15. The cables 5 connect the bridge tower 4 and the composite steel 2. The bridge tower 5 is welded to the composite steel 2. The cables 5 apply tension to the composite steel 2, apply tension to the vertical prestressed tendons vertically, and apply shear force to the first corbel horizontally. Due to the anchoring effect, the box girder top plate 1 is also subjected to vertical lifting force, and the bridge tower 4 is subjected to the tension of the cables 5. The bridge tower 5 transfers the force to the composite steel 2 above the pier, and the composite steel 2 then transfers the load to the box girder block 0 9. Block 0 9 bears the force and transfers it to the middle support 6, and then transfers it to the foundation through the pier 7 and foundation 8. The axial pressure on the composite steel in the cable area and the axial tension in the cable-free area are all borne by the first corbel for shear resistance. In this way, excessive pressure and tension are borne by the composite steel and the first corbel instead of the main beam itself, avoiding the adverse effects of excessive axial force on the main beam. At the same time, the main beam is subjected to an upward lifting force, which enhances the main beam's bending and shear resistance, reduces the downward deflection of the main beam, and can inhibit the development of cracks in the main beam.

[0061] Based on the cable-beam anchoring structure for strengthening a cable-stayed system described in the above embodiment, this embodiment provides a construction method for strengthening a cable-stayed system. The specific construction steps are as follows:

[0062] Step 1: Review the design data of relevant bridges and obtain the actual service performance of the bridges through field measurements. Determine the required load-bearing capacity of the pre-reinforced bridges based on the owner's requirements. Analyze and calculate the stresses on the pylons, cables, composite steel sections, and connection devices to determine the specific size, quantity, steel grade, and layout of the reinforcement components.

[0063] Step 2: Calculate the force of the cable through step 1 and determine the tensioning sequence and tensioning force of the cable;

[0064] Step 3: The processing plant processes the bridge tower, composite steel, and steel anchor beams, and drills holes in the corresponding locations according to the construction drawings; a groove is chiseled out at the location where the vertical prestressed tendons 10 are located on the centerline of the main beam top plate, exposing the vertical prestressed tendons 10, passing them through the first bracket, connecting extension bolts, and anchoring the composite steel 2 to the box beam top plate 1;

[0065] Step 4: Determine the position of the bridge tower relative to the composite steel, weld the processed bridge tower segments upward one by one, and leave a cable tensioning construction platform at the corresponding position.

[0066] Step 5: Install a pulley and winch on the bridge tower 4 to lift the cable, pull the cable into the channel of the bridge tower 4 in sequence, pass it through the steel anchor beam 24, and anchor it with the second cable anchor head 23; install the other end of the cable on the ear plate 18 and anchor it with the first cable anchor head 20.

[0067] Step 6: Tension the cables in sequence to the required tension;

[0068] Step 7: Drill a third hole 21 at the location where the cable passes through the upper horizontal steel plate 11, splice and weld them together; perform anti-corrosion and anti-rust treatment on all steel components, and the continuous beam bridge reinforcement is completed.

[0069] In some embodiments, the tensile strength of the vertical prestressed tendons conforms to the following formula:

[0070]

[0071] Where:

[0072] F is the cable tension;

[0073] e is the vertical distance from the cable anchoring position to the first drill hole;

[0074] d is the longitudinal spacing distance of the first borehole;

[0075] θ is the horizontal angle between the cable and the main beam top plate;

[0076] n is the number of vertical prestressing tendons in a segment;

[0077] γ1 is the safety factor;

[0078] A is the cross-sectional area of ​​the vertical prestressed tendons;

[0079] f is the tensile strength of the vertical prestressed tendons.

[0080] In some embodiments, the welding strength of the first corbel and the combined steel section complies with the following formula:

[0081] N1+N2≥γ2Fcosθ

[0082] Where:

[0083] F is the cable tension;

[0084] N1 is the front fillet weld bearing capacity;

[0085] N2 is the side fillet weld bearing capacity;

[0086] γ2 is the safety factor

[0087] θ is the horizontal angle between the cable and the main beam top plate;

[0088] in,

[0089] β f The strength design value increase factor of the front fillet weld;

[0090] h e ,h e ' is the effective thickness of the fillet weld;

[0091] ∑l w ,∑l w ' is the sum of the calculated lengths of the fillet welds on one side of the connection;

[0092] Design strength value of fillet weld.

[0093] Furthermore, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present invention with equivalent elements, modifications, omissions, combinations, for example, cross-cutting schemes, adaptations, or changes. The elements in the claims are to be interpreted broadly based on the language employed in the claims and are not limited to the examples described in this specification or during the prosecution of this application, which examples are to be interpreted as non-exclusive. Therefore, the specification and examples are intended to be considered as examples only, with the true scope and spirit being indicated by the following claims and their full scope of equivalents.

[0094] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more of their solutions) can be used in combination with each other. For example, those of ordinary skill in the art may use other embodiments when reading the above description. In addition, in the above-mentioned specific embodiments, various features can be grouped together to simplify the present invention. This should not be interpreted as an intention that a feature of an invention that is not claimed for protection is necessary for any claim. On the contrary, the subject matter of the present invention may be less than all the features of the embodiments of a particular invention. Thus, the following claims are incorporated into the specific embodiments as examples or embodiments, wherein each claim is independently a separate embodiment, and it is considered that these embodiments can be combined with each other in various combinations or arrangements. The scope of the present invention should be determined with reference to the appended claims and the full scope of equivalents to which these claims are entitled.

Claims

1. A construction method for strengthening a cable-stayed system, characterized in that: A cable-beam anchoring structure for strengthening a cable-stayed system comprises a box beam top plate (1), a composite steel (2), a first bracket (3), a bridge tower (4), a cable (5), a support (6), a bridge pier (7), a foundation (8), a No. 0 block (9), vertical prestressed tendons (10), an upper horizontal steel plate (11), a vertical steel plate (12), a lower horizontal steel plate (13), an anchor bolt (14), an extension device (15), a first borehole (16), a second borehole (17), an ear plate (18), a local reinforcement steel plate (19), a first cable anchor head (20), a third borehole (21), a second bracket (22), a second cable anchor head (23), a steel anchor beam (24), and a main beam (25); The main beam of the original structure transmits force to the foundation through the bridge pier (7) and the foundation (8), and the main beam (25), the bridge pier (7) and the foundation (8) form a continuous box beam bridge; The first bracket (3) is a hollow trapezoidal structure formed by welding steel plates; the combined steel (2) is welded by an upper horizontal steel plate (11), a vertical steel plate (12), a lower horizontal steel plate (13), a first bracket (3), an ear plate (18), and a local reinforcement steel plate (19); the first drill hole (16) and the second drill hole (17) are respectively provided on the lower horizontal steel plate (3) and the first bracket (13); the vertical prestressed tendons (10) are extended by the extension device (15); the combined steel (2) and the box beam top plate (1) are anchored together by extension bolts; The bridge tower (4) is composed of a second brace (22) and a steel anchor beam (24), and the bridge tower (4) is welded to the combined steel (2); the horizontal component of the cable (5) is borne by the steel anchor beam (24), and the vertical component is transmitted to the bridge tower (4) by the second brace (22); the cable (5) is anchored to the combined steel (2) and the bridge tower (4) respectively through a first cable anchor head (20) and a second cable anchor head (23); The construction method comprises: Step 1: Obtain the actual service performance of the bridge through field measurements. Determine the required load-bearing capacity of the pre-reinforced bridge based on construction requirements. Analyze and calculate the stresses on the pylons, cables, composite steel, and connection devices. This will determine the specific size, quantity, steel grade, and layout of the reinforcement components. Step 2: Calculate the force of the cable through step 1 and determine the tensioning sequence and tensioning force of the cable; Step 3: The processing plant processes the bridge tower, the composite steel, and the steel anchor beam, and punches holes at the corresponding positions according to the construction drawings; a groove is chiseled out at the position where the vertical prestressed tendons (10) are located on the center line of the main beam top plate, exposing the vertical prestressed tendons (10), passing through the first bracket, connecting the extension bolts, and anchoring the composite steel (2) on the box beam top plate (1); Step 4: Determine the position of the bridge tower relative to the composite steel, weld the processed bridge tower segments upward one by one, and reserve a cable tensioning construction platform at the corresponding position; Step 5: Install a pulley and a winch on the bridge tower (4) to lift the cable, pull the cable into the hole of the bridge tower (4) in sequence, pass it through the steel anchor beam (24), and anchor it with the second cable anchor head (23); install the other end of the cable on the ear plate (18) and anchor it with the first cable anchor head (20); Step 6: Tension the cables in sequence to the required tension; Step 7: drill a third hole (21) at the location where the cable passes through the upper horizontal steel plate (11), splice and weld them together; perform anti-corrosion and anti-rust treatment on all steel components, and the continuous beam bridge reinforcement is completed.

2. The construction method for strengthening the cable-stayed system according to claim 1, characterized in that: The tensile strength of the vertical prestressed tendons conforms to the following formula: Where: F is the cable tension; e is the vertical distance from the cable anchoring position to the first drill hole; d is the longitudinal spacing distance of the first borehole; θ is the horizontal angle between the cable and the main beam top plate; n is the number of vertical prestressing tendons in a segment; γ1 is the safety factor; A is the cross-sectional area of ​​the vertical prestressed tendons; f is the tensile strength of the vertical prestressed tendons.

3. The construction method for strengthening the cable-stayed system according to claim 1, characterized in that: The welding strength of the first bracket and the combined steel conforms to the following formula: N1+N2≥γ2Fcosθ Where: F is the cable tension force; N1 is the front fillet weld bearing capacity; N2 is the side fillet weld bearing capacity; γ2 is the safety factor θ is the horizontal angle between the cable and the main beam top plate; in, β f The strength design value increase factor of the front fillet weld; h e ,h e ' is the effective thickness of the fillet weld; ∑l w ,∑l w ' is the sum of the calculated lengths of the fillet welds on one side of the connection; Design strength value of fillet weld.

4. Application of the construction method according to any one of claims 1 to 3 in a standard three-span single-box double-chamber PSC continuous beam bridge.

5. The application of the construction method according to any one of claims 1 to 3 in PSC continuous box girder bridges of various structures combined between the bridge span types of double-span beams, three-span beams, and multi-span beams and the box chamber types of single-box single chamber, single-box double chamber, single-box double chamber, and multi-box multi-chamber.

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