Variable cross-section pier top fixing structure and construction method

Abstract

The invention relates to a variable cross-section pier top fixing structure which comprises a pier, a plurality of first anchor bolts, a plurality of second anchor bolts and a box girder, the pier is provided with a uniform cross-section area and a variable cross-section area, one side of the pier is provided with a first pull rod structure, and the first pull rod structure is provided with at least one row of first anchor bolt holes and at least one row of second anchor bolt holes; a plurality of first anchor bolts penetrate through the first anchor bolt holes to be fixed to the uniform-section area of the bridge pier, a plurality of second anchor bolts penetrate through the second anchor bolt holes to be fixed to the variable-section area of the bridge pier, and the inner diameter of the first anchor bolt holes is smaller than that of the second anchor bolt holes; the box girder is supported above the bridge pier and fixedly provided with a second pull rod structure, and the second pull rod structure is hinged to the first pull rod structure. The second anchor bolt penetrates through the anchor bolt hole with the large inner diameter and is fixed to the variable cross-section area of the bridge pier, so that the second anchor bolt resists tensile force and does not bear shear force, and the technical problems that in the related technology, the anchor bolt located in the variable cross-section area of the bridge pier cannot bear the shear force, and consequently an anchor bolt lever arm is long and prone to damage are solved.

Description

Technical Field

[0001] The present application relates to the field of bridge engineering, and in particular to a variable-section pier top fixing structure and a construction method. Background Art

[0002] With the booming development of the transportation industry, vehicle overloading has occurred frequently, increasing the risk of bridge overturning. Due to its simple structure and convenient construction, adding tie rods is often used to reinforce bridges against overturning.

[0003] In related technologies, variable-section bridge piers are widely used in bridge engineering due to their good visual effects. The pier body of a variable-section bridge pier has an overall variable section, the pier top cap beam has a constant section, and the anchor bolts located on the pier body are in the variable section area, resulting in a longer anchor bolt lever arm that cannot withstand the bending stress generated by the shear force. It is necessary to fill mortar between the pier top steel anchor plate and the pier body, but the mortar is easy to fall off, causing the anchor bolts to be easily damaged.

[0004] Therefore, it is necessary to design a new variable-section pier top fixed structure to overcome the above problems. Summary of the invention

[0005] The present application provides a variable-section pier top fixing structure and construction method, which can solve the technical problem in the related art that the anchor bolts located in the variable-section area of ​​the pier cannot withstand the bending stress generated by the shear force, resulting in a long anchor bolt lever arm and easy damage.

[0006] In a first aspect, an embodiment of the present application provides a variable-section pier top fixing structure, comprising: a pier, a plurality of first anchor bolts, a plurality of second anchor bolts and a box girder, wherein the pier has a uniform cross-sectional area and a variable cross-sectional area, and a first tie rod structure is provided on one side of the pier, the first tie rod structure is provided with at least one row of first anchor bolt holes and at least one row of second anchor bolt holes; a plurality of the first anchor bolts are fixed to the uniform cross-sectional area of ​​the pier through the first anchor bolt holes, and a plurality of the second anchor bolts are fixed to the variable cross-sectional area of ​​the pier through the second anchor bolt holes, wherein the diameter of the first anchor bolts is equal to the diameter of the second anchor bolts, and the inner diameter of the first anchor bolt holes is smaller than the inner diameter of the second anchor bolt holes; the box girder is supported above the pier, and the box girder is fixed with a second tie rod structure, and the second tie rod structure and the first tie rod structure are hinged.

[0007] In combination with the first aspect, in one embodiment, the first tension rod structure includes an anchor plate and a transverse ear plate, the anchor plate is provided with at least one row of the first anchor holes and at least one row of the second anchor holes, and the anchor plate is fixed to one side of the pier through a plurality of the first anchors and a plurality of the second anchors, the anchor plate is vertically connected to the transverse ear plate, and the transverse ear plate is hinged to the second tension rod structure.

[0008] In combination with the first aspect, in one embodiment, the second pull rod structure includes a support plate and a vertical ear plate, the support plate is fixed to the box beam, the support plate and the vertical ear plate are vertically connected, one end of the vertical ear plate is fixed to the support plate, and the other end of the vertical ear plate is hinged to the transverse ear plate through a pin shaft.

[0009] In combination with the first aspect, in one embodiment, a plurality of the first anchor bolts are symmetrically arranged along the axis of the vertical ear plate, and a plurality of the second anchor bolts are symmetrically arranged along the axis of the vertical ear plate.

[0010] In combination with the first aspect, in one implementation, mortar is filled between the anchor plate and the bridge pier.

[0011] In combination with the first aspect, in one embodiment, the anchor plate includes a transverse plate and a vertical plate, the transverse plate is connected to the vertical plate to form a T-shape, the transverse plate is provided with at least one row of the first anchor holes, and the vertical plate is provided with at least one row of the second anchor holes.

[0012] In combination with the first aspect, in one implementation, the difference between the inner diameter of the first anchor bolt hole and the inner diameter of the second anchor bolt hole is in the range of 3 to 5 mm.

[0013] In combination with the first aspect, in one implementation, the number of the first anchor bolts is determined according to the following formula:

[0014]

[0015] Wherein, N is the total number of first anchor bolts, F is the overturning force exerted on the second tie rod structure, and V is the shear design bearing capacity of the first anchor bolts.

[0016] In combination with the first aspect, in one embodiment, the length of the first anchor bolt is smaller than the length of the second anchor bolt.

[0017] In a second aspect, an embodiment of the present application provides a construction method for a variable-section pier top fixed structure, which comprises the following steps:

[0018] The first step is to pass a plurality of first anchor bolts through first anchor bolt holes and fix them to the uniform cross-section area of ​​the pier, pass a plurality of second anchor bolts through second anchor bolt holes and fix them to the variable cross-section area of ​​the pier, and fill mortar between the first tie rod structure and the pier.

[0019] Step 2: Install the second tie rod structure at the bottom of the box beam, and hinge the second tie rod structure and the first tie rod structure through a pin shaft.

[0020] The beneficial effects brought by the technical solution provided in the embodiments of the present application include:

[0021] The method is implemented by passing a plurality of first anchor bolts through first anchor bolt holes to fix them to the uniform cross-section area of ​​the pier, and passing a plurality of second anchor bolts through second anchor bolt holes to fix them to the variable cross-section area of ​​the pier, wherein the inner diameter of the first anchor bolt holes is smaller than the inner diameter of the second anchor bolt holes, so that the plurality of first anchor bolts resist the shear force generated by the overturning of the bridge, and the plurality of second anchor bolts resist the tensile force generated by the overturning moment without being subjected to the shear force, thereby solving the technical problem in the related art that the anchor bolts located in the variable cross-section area of ​​the pier cannot withstand the bending stress generated by the shear force, resulting in a long anchor bolt lever arm and easy damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 A schematic structural diagram of a variable-section pier top fixing structure provided in an embodiment of the present application;

[0024] Figure 2 for Figure 1 Sectional view of AA in the middle;

[0025] Figure 3 A schematic diagram of the structure of the anchor plate provided in the embodiment of the present application;

[0026] Figure 4 A schematic diagram of the principle of calculating the tension exerted on the first anchor bolt and the second anchor bolt provided in an embodiment of the present application.

[0027] In the figure: 1, bridge pier; 2, first tie rod structure; 21, anchor plate; 211, first anchor bolt hole; 212, second anchor bolt hole; 22, transverse ear plate; 23, first stiffening plate; 3, first anchor bolt; 4, second anchor bolt; 5, box girder; 6, second tie rod structure; 61, support plate; 62, vertical ear plate; 63, second stiffening plate; 7, pin shaft; 8, mortar. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] The embodiment of the present application provides a variable-section pier top fixing structure and construction method, which can solve the technical problem that the anchor bolts located in the variable-section area of ​​the pier cannot withstand the bending stress generated by the shear force, resulting in a long anchor bolt lever arm and easy damage.

[0030] See also Figure 1-3 As shown, an embodiment of the present application provides a variable-section pier top fixing structure, which includes: a pier 1, a plurality of first anchor bolts 3, a plurality of second anchor bolts 4 and a box girder 5, wherein the pier 1 has a uniform cross-sectional area and a variable cross-sectional area, and a first tie rod structure 2 is provided on one side of the pier 1, wherein the first tie rod structure 2 is provided with at least one row of first anchor bolt holes 211 and at least one row of second anchor bolt holes 212; a plurality of first anchor bolts 3 are fixed to the uniform cross-sectional area of ​​the pier 1 through the first anchor bolt holes 211, and a plurality of second anchor bolts 4 are fixed to the variable cross-sectional area of ​​the pier 1 through the second anchor bolt holes 212, wherein the diameter of the first anchor bolts 3 is equal to the diameter of the second anchor bolts 4, and the inner diameter of the first anchor bolt holes 211 is smaller than the inner diameter of the second anchor bolt holes 212; the box girder 5 is supported above the pier 1, and the box girder 5 is fixed with a second tie rod structure 6, and the second tie rod structure 6 is hinged to the first tie rod structure 2.

[0031] In this embodiment, the cross-sectional areas of the piers 1 located in the equal cross-sectional area are equal, and the cross-sectional area of ​​the piers 1 located in the variable cross-sectional area gradually decreases. At least one row of the first anchor holes 211 can be set as one row of the first anchor holes 211 or more rows of the first anchor holes 211. Preferably, at least one row of the first anchor holes 211 is set as two rows of the first anchor holes 211. At least one row of the second anchor holes 212 can be set as one row of the second anchor holes 212 or more rows of the second anchor holes 212. Preferably, at least one row of the second anchor holes 212 is set as two rows of the second anchor holes 212. The plurality of first anchor bolts 3 can be set as four first anchor bolts 3 or more first anchor bolts 3. Preferably, the plurality of first anchor bolts 3 are set as eight first anchor bolts 3. The plurality of second anchor bolts 4 can be set as two second anchor bolts 4 or more second anchor bolts 4. Preferably, the plurality of second anchor bolts 4 are set as four second anchor bolts. 4. The number of the first anchor bolts 3 corresponds to the number of the first anchor bolt holes 211, and the number of the second anchor bolts 4 corresponds to the number of the second anchor bolt holes 212. The inner diameter of the first anchor bolt hole 211 is slightly larger than the diameter of the first anchor bolt 3. Exemplarily, the inner diameter of the first anchor bolt hole 211 is 0.5 mm larger than the diameter of the first anchor bolt 3, so that the first anchor bolt 3 contacts the inner wall of the first anchor bolt hole 211. The inner diameter of the second anchor bolt hole 212 is larger than the diameter of the second anchor bolt 4, so that the second anchor bolt 4 may not contact the inner wall of the second anchor bolt hole 212. The second tie rod structure 6 is subjected to the overturning force of the box girder 5, so that the first tie rod structure 2 is subjected to upward shear force and rightward tensile force, so that the plurality of the first anchor bolts 3 resist the shear force generated by the overturning of the bridge, and the plurality of the second anchor bolts 4 resist the tensile force generated by the overturning moment without bearing the shear force. There is no need to set a longer anchor in the variable cross-section area. Even if the mortar 8 falls off, it will not affect the force on the anchor bolts.

[0032] In this embodiment, multiple first anchor bolts 3 are fixed to the uniform cross-sectional area of ​​the pier 1 through the first anchor bolt holes 211, and multiple second anchor bolts 4 are fixed to the variable cross-sectional area of ​​the pier 1 through the second anchor bolt holes 212, wherein the inner diameter of the first anchor bolt holes 211 is smaller than the inner diameter of the second anchor bolt holes 212, so that the multiple first anchor bolts 3 can resist the shear force generated by the overturning of the bridge, and the multiple second anchor bolts 4 can resist the tensile force generated by the overturning moment without bearing the shear force. There is no need to set longer anchor bolts in the variable cross-sectional area. Even if the mortar 8 falls off, it will not affect the force on the anchor bolts. This solves the technical problem in the related art that the anchor bolts located in the variable cross-sectional area of ​​the pier 1 cannot withstand the bending stress generated by the shear force, resulting in a longer anchor bolt lever arm and easy damage.

[0033] Further, see Figure 1-3As shown, in some embodiments, the first tie rod structure 2 includes an anchor plate 21 and a transverse ear plate 22, the anchor plate 21 is provided with at least one row of the first anchor holes 211 and at least one row of the second anchor holes 212, and the anchor plate 21 is fixed to one side of the pier 1 by a plurality of the first anchors 3 and a plurality of the second anchors 4, the anchor plate 21 is vertically connected to the transverse ear plate 22, and the transverse ear plate 22 is hinged to the second tie rod structure 6.

[0034] In this embodiment, the transverse ear plate 22 is welded to one side of the anchor plate 21, and the number of the transverse ear plates 22 can be set to one or two or more. Exemplarily, the second tie rod structure 6 is clamped between the two transverse ear plates 22 and hinged to the two transverse ear plates 22, so that the overturning force of the box girder 5 on the second tie rod structure 6 is converted into an upward shear force and a rightward tensile force on the transverse ear plate 22, and the force is transmitted to the plurality of first anchor bolts 3 and the plurality of second anchor bolts 4 through the anchor plate 21. A first stiffening plate 23 is provided on one side of each transverse ear plate 22, and the first stiffening plate 23 is fixed to the anchor plate 21.

[0035] Further, see Figure 1 and Figure 2 As shown, in some embodiments, the second tie rod structure 6 includes a support plate 61 and a vertical ear plate 62, the support plate 61 is fixed to the box beam 5, the support plate 61 and the vertical ear plate 62 are vertically connected, one end of the vertical ear plate 62 is fixed to the support plate 61, and the other end of the vertical ear plate 62 is hinged to the transverse ear plate 22 through a pin shaft 7.

[0036] In this embodiment, the support plate 61 is fixedly installed at the bottom of the box beam 5, and the support plate 61 can be set as a steel plate. The support plate 61 is vertically connected to the vertical ear plate 62. Second stiffening plates 63 are provided on both sides of the vertical ear plate 62. The second stiffening plates 63 are fixed to the support plate 61. The vertical ear plate 62 is hinged to the transverse ear plate 22 through the pin shaft 7, so that the overturning force of the box beam 5 on the vertical ear plate 62 can be converted into an upward shear force and a rightward tensile force on the transverse ear plate 22.

[0037] Further, see Figure 2 As shown, in some embodiments, a plurality of the first anchor bolts 3 are symmetrically arranged along the axis of the vertical ear plate 62 , and a plurality of the second anchor bolts 4 are symmetrically arranged along the axis of the vertical ear plate 62 .

[0038] In this embodiment, the multiple first anchor bolts 3 can be set to four first anchor bolts 3 or more first anchor bolts 3, and the multiple second anchor bolts 4 can be set to two second anchor bolts 4 or more second anchor bolts 4. Preferably, the multiple first anchor bolts 3 are set to eight first anchor bolts 3, and the multiple second anchor bolts 4 are set to four second anchor bolts 4. The eight first anchor bolts 3 are set to two rows, and the four second anchor bolts 4 are set to two rows. The eight first anchor bolts 3 are symmetrically arranged along the axis of the vertical ear plate 62, and the four second anchor bolts 4 are symmetrically arranged along the axis of the vertical ear plate 62, so that each first anchor bolt 3 and each second anchor bolt 4 are subjected to uniform force, thereby improving the stability of the variable-section pier top fixed structure.

[0039] Further, see Figure 1 and Figure 2 As shown, in some embodiments, mortar 8 is filled between the anchor plate 21 and the pier 1 .

[0040] In this embodiment, the mortar 8 can be set as epoxy mortar to protect the second anchor bolt 4. Even if the mortar 8 falls off, it will not affect the force of the second anchor bolt 4.

[0041] Further, see Figure 3 As shown, in some embodiments, the anchor plate 21 includes a transverse plate and a vertical plate, the transverse plate is connected to the vertical plate to form a T-shape, the transverse plate is provided with at least one row of the first anchor holes 211, and the vertical plate is provided with at least one row of the second anchor holes 212.

[0042] In this embodiment, the transverse plate is provided with one row of the first anchor holes 211 or more rows of the first anchor holes 211, and the vertical plate is provided with one row of the second anchor holes 212 or more rows of the second anchor holes 212. Preferably, the transverse plate is provided with two rows of the first anchor holes 211, and the vertical plate is provided with two rows of the second anchor holes 212. The two rows of the first anchor holes 211 and the two rows of the second anchor holes 212 are symmetrically arranged along the axis of the vertical ear plate 62 to cooperate with the use of multiple first anchors 3 and multiple second anchors 4. The anchor plate 21 is arranged in a T shape according to the arrangement of the first anchor holes 211 and the second anchor holes 212, so that the anchor plate 21 is fixed to one side of the pier 1 in an optimal stress state.

[0043] Further, see Figure 1-3 As shown, in some embodiments, the difference between the inner diameter of the first anchor hole 211 and the inner diameter of the second anchor hole 212 ranges from 3 to 5 mm.

[0044] In this embodiment, the difference between the inner diameter of the first anchor hole 211 and the inner diameter of the second anchor hole 212 can be set in the range of 3 to 5 mm, so that the second anchor 4 can resist the tensile force generated by the overturning moment without being subjected to shear force, and may not contact the inner wall of the second anchor hole 212, and can cooperate with the nut to fix the anchor plate 21.

[0045] Further, see Figure 1 and Figure 2 As shown, in some embodiments, the number of the first anchor bolts 3 is determined according to the following formula:

[0046]

[0047] Wherein, N is the total number of first anchor bolts, F is the overturning force exerted on the second tie rod structure, and V is the shear design bearing capacity of the first anchor bolts.

[0048] In this embodiment, the total number N of the first anchor bolts can be set within a certain range according to specifications. When the shear design bearing capacity V of the first anchor bolts meets the requirements, the total number N of the first anchor bolts can be determined.

[0049] Further, see Figure 1 As shown, in some embodiments, the length of the first anchor bolt 3 is smaller than the length of the second anchor bolt 4 .

[0050] In this embodiment, the anchoring depths of the first anchor bolt 3 and the second anchor bolt 4 are the same, and the length of the second anchor bolt 4 increases as the width of the pier 1 located in the variable cross-section area changes.

[0051] Further, see Figure 1 As shown, in some embodiments, the present application provides a construction method for a variable-section pier top fixed structure, which includes the following steps:

[0052] Step 1: Pass multiple first anchor bolts 3 through the first anchor bolt holes 211 and fix them to the uniform cross-sectional area of ​​the pier 1, pass multiple second anchor bolts 4 through the second anchor bolt holes 212 and fix them to the variable cross-sectional area of ​​the pier 1, and fill mortar 8 between the first tie rod structure 2 and the pier 1.

[0053] Step 2: Install the second tie rod structure 6 at the bottom of the box beam 5 , and hinge the second tie rod structure 6 and the first tie rod structure 2 through the pin shaft 7 .

[0054] In this embodiment, the number of the first anchor bolts 3 and the second anchor bolts 4 is determined, a plurality of the first anchor bolts 3 are passed through the first anchor bolt holes 211 and fixed to the uniform cross-sectional area of ​​the pier 1, a plurality of the second anchor bolts 4 are passed through the second anchor bolt holes 212 and fixed to the variable cross-sectional area of ​​the pier 1, and the mortar 8 is filled between the anchor plate 21 and the pier 1, the support plate 61 is anchored at the bottom of the box girder 5, the vertical ear plate 62 is welded to the support plate 61, and the transverse ear plate is welded on one side of the anchor plate 21 22, the vertical ear plate 62 and the transverse ear plate 22 are hinged through the pin shaft 7, the vertical ear plate 62 is subjected to the overturning force of the box beam 5, the anchor plate 21 is subjected to upward shear force and rightward tensile force, the plurality of the first anchor bolts 3 resist the shear force caused by the overturning of the bridge, and the plurality of the second anchor bolts 4 resist the tensile force caused by the overturning moment without being subjected to shear force, so as to achieve no contact with the inner wall of the second anchor bolt hole 212, and no longer need to set a longer anchor bolt in the variable cross-section area, even if the mortar 8 falls off, it will not affect the force on the anchor bolt.

[0055] The tension on the first anchor bolt 3 and the second anchor bolt 4 satisfies the following formula:

[0056]

[0057] M=F·L(3),

[0058] Among them, T i is the tension on the i-th anchor bolt, y i is the height difference between the ith anchor bolt and the top anchor bolt, F is the overturning force on the second tie rod structure, L is the distance between the pin axis and the anchor plate, and M is the moment of the overturning force, as shown in Figure 4 As shown, exemplarily, the overturning force F on the second tie rod structure is set to 200 kN, the distance L between the pin axis and the anchor plate is set to 0.3 m, the eight first anchor bolts 3 can be arranged in two rows, the four second anchor bolts 4 can be arranged in two rows, the first row of the first anchor bolts 3 are top anchor bolts, the second row of the second anchor bolts 4 are bottom anchor bolts, the height difference between the first row of the first anchor bolts 3 and the top anchor bolts is set to 0 m, the height difference between the second row of the first anchor bolts 3 and the top anchor bolts is set to 0.2 m, and the height difference between the first row of the second anchor bolts 4 and the top anchor bolts is set to 0.4m, the height difference between the second anchor bolt 4 in the second row and the top anchor bolt is set to 0.6m, the tension applied to each of the first anchor bolts 3 in the first row is 0, the tension applied to each of the first anchor bolts 3 in the second row is 6.7kN, the tension applied to each of the second anchor bolts 3 in the first row is 13.3kN, the tension applied to each of the second anchor bolts 4 in the second row is 20kN, and the second anchor bolts 4 are mainly used to resist the tension generated by the overturning moment.

[0059] The shear force on the first anchor bolt 3 and the second anchor bolt 4 satisfies the following formula:

[0060]

[0061] Among them, V is the shear design bearing capacity of the first anchor, F is the overturning force exerted on the second tension rod structure, and N is the total number of first anchors. Exemplarily, the number of first anchors is set to 8, the overturning force F exerted on the second tension rod structure is set to 200 kN, the shear force V exerted on each of the first anchors 3 is 25 kN, and the shear force V exerted on each of the second anchors 4 is 0. The first anchors 3 are mainly used to resist the shear force caused by the overturning of the bridge, and the second anchors 4 do not bear shear force.

[0062] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0063] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0064] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A variable cross-section pier top fixed structure, characterized in that: It includes: A bridge pier (1), the bridge pier (1) having a uniform cross-section area and a variable cross-section area, and a first tie rod structure (2) is provided on one side of the bridge pier (1), the first tie rod structure (2) being provided with at least one row of first anchor bolt holes (211) and at least one row of second anchor bolt holes (212); A plurality of first anchor bolts (3) and a plurality of second anchor bolts (4), wherein the plurality of first anchor bolts (3) pass through the first anchor bolt holes (211) and are fixed to the uniform cross-sectional area of ​​the bridge pier (1), and the plurality of second anchor bolts (4) pass through the second anchor bolt holes (212) and are fixed to the variable cross-sectional area of ​​the bridge pier (1), wherein the diameter of the first anchor bolts (3) is equal to the diameter of the second anchor bolts (4), and the inner diameter of the first anchor bolt holes (211) is smaller than the inner diameter of the second anchor bolt holes (212); A box beam (5), wherein the box beam (5) is supported above the bridge pier (1), and the box beam (5) is fixedly provided with a second tie rod structure (6), wherein the second tie rod structure (6) is hinged to the first tie rod structure (2).

2. The variable cross-section pier top fixing structure according to claim 1, characterized in that: The first tie rod structure (2) comprises an anchor plate (21) and a transverse ear plate (22); the anchor plate (21) is provided with at least one row of the first anchor bolt holes (211) and at least one row of the second anchor bolt holes (212); the anchor plate (21) is fixed to one side of the pier (1) through a plurality of the first anchor bolts (3) and a plurality of the second anchor bolts (4); the anchor plate (21) is vertically connected to the transverse ear plate (22); and the transverse ear plate (22) is hinged to the second tie rod structure (6).

3. The variable cross-section pier top fixed structure according to claim 2, characterized in that: The second tie rod structure (6) includes a support plate (61) and a vertical ear plate (62), wherein the support plate (61) is fixed to the box beam (5), the support plate (61) and the vertical ear plate (62) are vertically connected, one end of the vertical ear plate (62) is fixed to the support plate (61), and the other end of the vertical ear plate (62) is hinged to the transverse ear plate (22) through a pin shaft (7).

4. The variable cross-section pier top fixing structure according to claim 3, characterized in that: A plurality of the first anchor bolts (3) are symmetrically arranged along the axis of the vertical ear plate (62), and a plurality of the second anchor bolts (4) are symmetrically arranged along the axis of the vertical ear plate (62).

5. The variable cross-section pier top fixed structure according to claim 2, characterized in that: Mortar (8) is filled between the anchor plate (21) and the bridge pier (1).

6. The variable cross-section pier top fixed structure according to claim 2, characterized in that: The anchoring plate (21) comprises a transverse plate and a vertical plate, wherein the transverse plate is connected to the vertical plate to form a T-shape, the transverse plate is provided with at least one row of the first anchor bolt holes (211), and the vertical plate is provided with at least one row of the second anchor bolt holes (212).

7. The variable cross-section pier top fixed structure according to claim 1, characterized in that: The difference between the inner diameter of the first anchor hole (211) and the inner diameter of the second anchor hole (212) is in the range of 3 to 5 mm.

8. The variable cross-section pier top fixing structure according to claim 1, characterized in that: The number of the first anchor bolts (3) is determined according to the following formula: Wherein, N is the total number of first anchor bolts, F is the overturning force exerted on the second tie rod structure, and V is the shear design bearing capacity of the first anchor bolts.

9. The variable cross-section pier top fixing structure according to claim 1, characterized in that: The length of the first anchor bolt (3) is smaller than the length of the second anchor bolt (4).

10. A construction method for the variable cross-section pier top fixed structure as claimed in claim 1, characterized in that: It includes the following steps: Passing a plurality of first anchor bolts (3) through first anchor bolt holes (211) and fixing them to the uniform cross-sectional area of ​​the bridge pier (1), passing a plurality of second anchor bolts (4) through second anchor bolt holes (212) and fixing them to the variable cross-sectional area of ​​the bridge pier (1), and filling mortar (8) between the first tie rod structure (2) and the bridge pier (1); A second tie rod structure (6) is installed at the bottom of the box beam (5), and the second tie rod structure (6) and the first tie rod structure (2) are hingedly connected via a pin shaft (7).

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