An elevation unloading fine adjustment device for erecting installation of a variable cross-section steel box girder and a use method thereof

Abstract

The application discloses a height unloading fine adjustment device for erecting and installing a variable cross-section steel box girder and a use method thereof. The device comprises an isosceles trapezoidal box base symmetrically distributed upward and downward, two isosceles trapezoidal box slides symmetrically distributed left and right between the isosceles trapezoidal box base and the isosceles trapezoidal box top, the longer base plane of the isosceles trapezoidal box slide is arranged vertically on the outer side, the two waist planes of each isosceles trapezoidal box slide are symmetrically and slidably arranged on the waist planes of the isosceles trapezoidal box base and the isosceles trapezoidal box top, and a tension bolt is horizontally and adjustably connected between the two isosceles trapezoidal box slides. The device has the advantages of high height fine adjustment precision, high unloading and falling amount control precision, low failure rate, uniform multi-point synchronous unloading, and high repeated turnover use rate.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to an elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders and its usage method. Background Technology

[0002] In the construction of variable cross-section steel box girders for bridges, temporary support systems are typically used for load-bearing. Because variable cross-section steel box girders require extremely high precision in alignment control, a height unloading and fine-tuning device must be installed at the top of the temporary support system. Traditionally, sandboxes are used as height unloading and fine-tuning devices for the erection and installation of variable cross-section steel box girders, which has the following technical drawbacks:

[0003] (1) Insufficient accuracy of elevation fine adjustment: The height of the sand box is adjusted by releasing sand, which makes it difficult to achieve millimeter-level precise fine adjustment.

[0004] (2) Low precision control of unloading and fall: The sand flows unevenly when the sand box is unloaded, making it difficult to precisely control the fall amount.

[0005] (3) High failure rate: During on-site construction, sand leakage, sand body dampness, caking and jamming are prone to occur.

[0006] (4) Difficulty in multi-point synchronous unloading: It is difficult to achieve synchronous and uniform unloading of sand boxes at multiple points. Uneven unloading can easily lead to additional stress in the variable cross-section steel box girder structure, affecting the installation and forming quality of the variable cross-section steel box girder.

[0007] (5) Poor compatibility with the bottom plate of the variable cross section steel box girder: The bottom plate of the variable cross section steel box girder is generally curved. Traditional sand boxes use steel plate pads for fine adjustment, which makes it difficult to ensure that the top of the sand box is fully in contact with the bottom plate of the steel box girder, thus affecting the load-bearing stability. Summary of the Invention

[0008] The purpose of this invention is to provide an elevation unloading fine-tuning device and its usage method for the erection and installation of variable cross-section steel box girders, in order to solve the problems of high failure rate of sand boxes, low accuracy of elevation fine-tuning, low accuracy of unloading and fall control, and difficulty in multi-point synchronous unloading.

[0009] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a height unloading fine-tuning device for the erection and installation of variable cross-section steel box girders, comprising:

[0010] An isosceles trapezoidal box-type base, in which the plane containing the longer base of the isosceles trapezoid is arranged horizontally downwards;

[0011] An isosceles trapezoidal box-type top seat is symmetrically distributed with the isosceles trapezoidal box-type base, with the plane containing the longer base of the isosceles trapezoid facing upwards.

[0012] The isosceles trapezoidal box-type slide is symmetrically distributed between the isosceles trapezoidal box-type base and the isosceles trapezoidal box-type top seat. The plane containing the longer base of the isosceles trapezoid is arranged vertically on the outer side. The two sides of each isosceles trapezoidal box-type slide are symmetrically slidably arranged on the inclined plane containing the sides of the isosceles trapezoidal box-type base and the inclined plane containing the sides of the isosceles trapezoidal box-type top seat.

[0013] Tie bolts are horizontally inserted and adjustablely connected to the two isosceles trapezoidal box slides.

[0014] Furthermore, the elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders provided by the present invention includes a tie bolt comprising a tie rod and nuts connected to both sides thereof, wherein the nuts are located on the outer side of the isosceles trapezoidal box slide on the corresponding side.

[0015] Furthermore, the elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders provided by the present invention further includes a pad passing through the tie bolt.

[0016] Furthermore, the elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders provided by the present invention includes an isosceles trapezoidal box base comprising a box bottom plate, multiple isosceles trapezoidal box uprights vertically and uniformly arranged on the box bottom plate, and lower inclined panels inclined and symmetrically arranged on the waists of both sides of the uprights of all the isosceles trapezoidal box bases.

[0017] Furthermore, the elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders provided by the present invention includes an isosceles trapezoidal box-type top seat comprising a box top plate, multiple isosceles trapezoidal box uprights vertically and uniformly arranged on the box top plate, and upper inclined panels inclined and symmetrically arranged on the waists of the uprights on both sides of all the isosceles trapezoidal box-type top seats.

[0018] Furthermore, the elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders provided by the present invention includes an isosceles trapezoidal box slide comprising a box side plate, multiple isosceles trapezoidal box web plates vertically and uniformly arranged on the box side plate, and sliding plates inclined and symmetrically arranged on the waists of the box web plates on both sides of all the isosceles trapezoidal box slides.

[0019] Furthermore, the elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders provided by the present invention includes a box partition between the adjacent box web plate and the box side plate of the isosceles trapezoidal box slide; a box partition between the adjacent box upright plate and the box bottom plate of the isosceles trapezoidal box base; and a box partition between the adjacent box upright plate and the box top plate of the isosceles trapezoidal box top seat.

[0020] Furthermore, the elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders provided by the present invention has a slot at one end of the lower inclined panel of the isosceles trapezoidal box base and the upper inclined panel of the isosceles trapezoidal box top seat that slides inward to the center to avoid the tie bolt.

[0021] Furthermore, the elevation unloading fine-tuning device for erecting and installing variable cross-section steel box girders provided by the present invention has a top plate profile that matches the bottom profile of the variable cross-section steel box girder.

[0022] To solve the above-mentioned technical problems, another technical solution provided by the present invention is: a method for using an elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders, wherein an isosceles trapezoidal box base is used as a reference, the variable cross-section steel box girder is erected and installed on the isosceles trapezoidal box top seat, and the height of the isosceles trapezoidal box top seat relative to the isosceles trapezoidal box base is adjusted by adjusting the sliding direction of the two isosceles trapezoidal box sliding seats relative to the inclined surfaces of the isosceles trapezoidal box base and the isosceles trapezoidal box top seat through tie bolts.

[0023] Compared with the prior art, the advantages of the elevation unloading fine-tuning device and its usage method for the erection and installation of variable cross-section steel box girders provided by the present invention are as follows:

[0024] High precision in elevation fine-tuning and high precision in unloading and fall control: Millimeter-level precise fine-tuning of the sliding direction of the two isosceles trapezoidal box slides relative to the isosceles trapezoidal box base and the isosceles trapezoidal box top seat is achieved by using tie bolts. This adjusts the height of the isosceles trapezoidal box top seat relative to the isosceles trapezoidal box base, thereby adjusting the elevation of the variable cross-section steel box girder erected on the isosceles trapezoidal box top seat or performing precise fine-tuning control during unloading. Compared with sand box adjustment, it has the advantages of high precision in elevation fine-tuning and high precision in unloading and fall control.

[0025] Multi-point synchronous and uniform unloading: By synchronously adjusting the tie bolts of the elevation unloading fine adjustment device distributed at multiple points under a certain variable cross-section steel box girder with the same magnitude, multi-point synchronous and uniform unloading can be achieved. It has the advantages of good coordination and uniform stress on the load-bearing variable cross-section steel box girder. It effectively avoids the problem of asynchronous and uneven unloading caused by uneven sand flow when unloading sand boxes distributed at multiple points. It also avoids the problem of additional stress generated in the variable cross-section steel box girder structure due to uneven unloading, thereby improving the installation and forming quality of the variable cross-section steel box girder.

[0026] Low failure rate: The millimeter-level precise micro-adjustment of the sliding direction of the two isosceles trapezoidal box slides relative to the isosceles trapezoidal box base and the isosceles trapezoidal box top seat is achieved by using tie bolts to adjust the elevation or unload of the isosceles trapezoidal box top seat relative to the isosceles trapezoidal box base. This avoids problems such as sand leakage and sand caking due to moisture in the sand box solution, thus reducing the failure rate and providing the advantage of wide applicability to various construction environments.

[0027] High reusability: The elevation unloading fine adjustment device consists of an isosceles trapezoidal box base and an isosceles trapezoidal box top seat symmetrically distributed vertically, two isosceles trapezoidal box slides symmetrically distributed horizontally, and a horizontally penetrating and adjustable connection to the two isosceles trapezoidal box slides. It has the advantages of simple structure, low cost and high reusability, avoiding the problem of low reusability caused by easy damage to the sand box. Attached Figure Description

[0028] Figure 1 This is a three-dimensional structural diagram of an elevation unloading and fine-tuning device used for the erection and installation of variable cross-section steel box girders.

[0029] Figure 2 This is a schematic diagram of the three-dimensional combined structure of the isosceles trapezoidal box-type base;

[0030] Figure 3 This is a three-dimensional disassembly diagram of an isosceles trapezoidal box-shaped base;

[0031] Figure 4 This is a schematic diagram of the three-dimensional combined structure of an isosceles trapezoidal box-type slide.

[0032] Figure 5 This is a three-dimensional disassembly diagram of an isosceles trapezoidal box-type slide.

[0033] Figure 6 This is a three-dimensional structural diagram of a tie bolt;

[0034] As shown in the figure:

[0035] 100. Elevation unloading fine-tuning device;

[0036] 110. Isosceles trapezoidal box base; 111. Box bottom plate; 112. Box upright plate; 113. Upper inclined panel; 114. Limiting plate; 115. Groove.

[0037] 120. Isosceles trapezoidal box-type top seat;

[0038] 130. Isosceles trapezoidal box-type slide; 131. Box side plate; 132. Box belly plate; 133. Sliding plate; 134. Box partition; 135. Through hole.

[0039] 140. Tie bolt, 141. Tie rod, 142. Nut, 143. Washer. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0041] Please refer to Figure 1 This invention provides an elevation unloading fine-tuning device 100 for the erection and installation of variable cross-section steel box girders, comprising an isosceles trapezoidal box base 110 and an isosceles trapezoidal box top 120 symmetrically distributed vertically, two isosceles trapezoidal box slides 130 symmetrically distributed horizontally, and tie bolts 140, wherein:

[0042] An isosceles trapezoidal box-type base 110, wherein the plane containing the longer base of the isosceles trapezoid is arranged horizontally downwards.

[0043] The isosceles trapezoidal box-type top seat 120 is symmetrically distributed vertically with the isosceles trapezoidal box-type base 110, with the plane containing the longer base of the isosceles trapezoid facing upwards.

[0044] The isosceles trapezoidal box slide 130 consists of two symmetrically distributed between the isosceles trapezoidal box base 110 and the isosceles trapezoidal box top 120. The plane containing the longer base of the isosceles trapezoid is arranged vertically on the outer side. The two sides of each isosceles trapezoidal box slide 130 are symmetrically slidably disposed on the inclined plane containing the sides of the isosceles trapezoidal box base 110 and the inclined plane containing the sides of the isosceles trapezoidal box top 120.

[0045] Tie bolts 140 are horizontally penetrating and adjustablely connected to the two isosceles trapezoidal box slides 130.

[0046] This invention also provides a method for using an elevation unloading fine-tuning device 100 for the erection and installation of variable cross-section steel box girders. Using an isosceles trapezoidal box base 110 as a reference, the variable cross-section steel box girder is erected and installed on an isosceles trapezoidal box top 120. The height of the isosceles trapezoidal box top 120 relative to the isosceles trapezoidal box base 110 is adjusted by adjusting the sliding direction of the two isosceles trapezoidal box slides 130 relative to the inclined surfaces of the isosceles trapezoidal box base 110 and the isosceles trapezoidal box top 120 using tie bolts 140, thereby adjusting the elevation or unloading the variable cross-section steel box girder.

[0047] The elevation unloading fine-tuning device 100 and its usage method for the erection and installation of variable cross-section steel box girders provided in this invention embodiment achieve millimeter-level precise micro-adjustment of the inclined sliding direction of two isosceles trapezoidal box slides 130 relative to the isosceles trapezoidal box base 110 and the isosceles trapezoidal box top seat 120, thereby adjusting the height of the isosceles trapezoidal box top seat 120 relative to the isosceles trapezoidal box base 110. This allows for elevation adjustment or unloading of the variable cross-section steel box girder erected on the isosceles trapezoidal box top seat 120, as well as precise micro-adjustment control during the unloading process. Compared with sand box adjustment, it has the advantages of high elevation micro-adjustment accuracy and high unloading drop control accuracy.

[0048] The elevation unloading fine-tuning device 100 and its usage method for the erection and installation of variable cross-section steel box girders provided in this invention can achieve synchronous and uniform unloading at multiple points by synchronously adjusting the tie bolts 140 of the elevation unloading fine-tuning device 100 distributed at multiple points below a certain variable cross-section steel box girder. This has the advantages of good coordination and uniform stress distribution on the variable cross-section steel box girder, i.e., uniform synchronous unloading at multiple points. It effectively avoids the problem of asynchronous and uneven unloading caused by uneven sand flow during multi-point sand box unloading, and avoids the problem of additional stress on the variable cross-section steel box girder structure due to uneven unloading, thereby improving the installation and forming quality of the variable cross-section steel box girder.

[0049] The elevation unloading fine-tuning device 100 and its usage method for the erection and installation of variable cross-section steel box girders provided in this invention embodiment achieve millimeter-level precise micro-adjustment of the inclined sliding direction of two isosceles trapezoidal box slides 130 relative to the isosceles trapezoidal box base 110 and the isosceles trapezoidal box top seat 120, thereby adjusting the elevation or unloading of the isosceles trapezoidal box top seat 120 relative to the isosceles trapezoidal box base 110. This avoids faults such as sand leakage and sand caking due to moisture in the sand box scheme, reduces the failure rate, and has the advantage of wide applicability to construction environments.

[0050] The elevation unloading fine-tuning device 100 for the erection and installation of variable cross-section steel box girders provided in this embodiment of the invention and its usage method are as follows: The elevation unloading fine-tuning device 100 consists of an isosceles trapezoidal box base 110 and an isosceles trapezoidal box top seat 120 symmetrically distributed vertically, two isosceles trapezoidal box slides 130 symmetrically distributed horizontally, and a horizontally penetrating and adjustable connection to the two isosceles trapezoidal box slides 130. It has the advantages of simple structure, low cost, and high reusability, avoiding the problem of low reusability caused by easy damage to sand boxes.

[0051] Please refer to Figure 1 and Figure 6The elevation unloading fine-tuning device 100 for the erection and installation of variable cross-section steel box girders provided in this embodiment of the invention includes a tie bolt 140 comprising a tie rod 141 and nuts 142 connected to both sides. The nuts 142 are located on the outer side of the corresponding isosceles trapezoidal box slide 130. By changing the position of the nuts 142 on the tie rod 141, the synchronous sliding of the two isosceles trapezoidal box slides 130 relative to the isosceles trapezoidal box base 110 and the isosceles trapezoidal box top 120 is achieved, thereby changing the height of the isosceles trapezoidal box top 120 relative to the isosceles trapezoidal box base 110. Because a variable cross-section steel box beam is mounted on the isosceles trapezoidal box base 110, after adjusting the height of the isosceles trapezoidal box top seat 120, the downward pressure of the variable cross-section steel box beam maintains the structural stability of the elevation unloading fine-tuning device 100, preventing the two isosceles trapezoidal box slides 130 from sliding synchronously back relative to the isosceles trapezoidal box base 110 and the isosceles trapezoidal box top seat 120. To ensure load-bearing strength, tie bolts 140 include, but are not limited to, two. Each tie bolt 140 also includes a pad 143 passing through it. Nuts 142 are pressed against the isosceles trapezoidal box slides 130 on both sides via the pads 143. After the position of the nuts 142 relative to the tie screws 141 is adjusted, the contact area is increased by the pads 143 to improve the locking force of the nuts 142 on the two isosceles trapezoidal box slides 130. The pads 143 can be square pads.

[0052] Please refer to Figures 2 to 3 To reduce costs, this invention provides an elevation unloading fine-tuning device 100 for the erection and installation of variable cross-section steel box girders. The isosceles trapezoidal box base 110 includes a box bottom plate 111, multiple isosceles trapezoidal box uprights 112 vertically and uniformly arranged on the box bottom plate 111, and inclined lower sloping panels 113 symmetrically arranged on both sides of the uprights 112 of all the isosceles trapezoidal box bases 110. The isosceles trapezoidal box base 110 in the figure illustrates three isosceles trapezoidal box uprights 112 of the same specifications and dimensions. The box bottom plate 111, uprights 112, and lower sloping panels 113 can all be made of 10mm thick Q235 steel plates welded together. The box bottom plate 111 is rectangular, the uprights 112 are isosceles trapezoids, and the lower sloping panels 113 are rectangular. The lower inclined panel 113 of the isosceles trapezoidal box base 110 has a slot 115 at one end that slides inward toward the center to avoid the tie bolt 140.

[0053] Please refer to Figures 1 to 3To reduce costs, the elevation unloading fine-tuning device 100 for the erection and installation of variable cross-section steel box girders provided in this embodiment of the invention has the same structural composition as the isosceles trapezoidal box-type top seat 120, which includes a box top plate, multiple isosceles trapezoidal box-type upright plates 112 vertically and uniformly arranged on the box top plate, and an upper inclined panel symmetrically arranged on both sides of the upright plates 112 of all the isosceles trapezoidal box-type top seats 120. Since the isosceles trapezoidal box-type top seats 120 and the isosceles trapezoidal box-type base 110 are symmetrically distributed vertically, their correspondence is as follows: the box top plate corresponds to the box bottom plate 111, the box upright plates 112 correspond to the upright plates 112 of the isosceles trapezoidal box-type base 110, and the upper inclined panel corresponds to the lower inclined panel 113, wherein the groove 115 of the upper inclined panel corresponds to the groove 115 of the lower inclined panel 113.

[0054] Please refer to Figures 4 to 5 To reduce costs, this invention provides an elevation unloading fine-tuning device 100 for the erection and installation of variable cross-section steel box girders. The isosceles trapezoidal box slide 130 includes a box side plate 131, multiple isosceles trapezoidal box web plates 132 vertically and uniformly arranged on the side plate 131, and sliding plates 133 obliquely and symmetrically arranged on the sides of the box web plates 132 of all the isosceles trapezoidal box slides 130. To ensure the structural stability of the isosceles trapezoidal box slide 130, a box partition 134 is provided between adjacent box web plates 132 and box side plates 131. The box partition 134 ensures the structural stability between adjacent box web plates 132 and prevents the box web plates 132 from shifting relative to the box side plates 131. Similarly, to ensure the structural stability of the isosceles trapezoidal box base 110 and the isosceles trapezoidal box top 120, a box partition 134 is provided between the adjacent box uprights 112 and the box bottom plate 111 of the isosceles trapezoidal box base 110; a box partition 134 is also provided between the adjacent box uprights and the box top plate of the isosceles trapezoidal box top 120. The box web 132 shown in the figure consists of three pieces, with the box web 132 aligned with the box uprights to ensure the stability of the overall load-bearing capacity.

[0055] Please refer to Figures 1 to 3 To ensure a stable sliding relationship between the isosceles trapezoidal box slide 130 and the isosceles trapezoidal box base 110 and isosceles trapezoidal box top 120, limiting plates 114 are vertically provided on both sides of the upper inclined panel 113 of the isosceles trapezoidal box base 110 and the lower inclined panel of the isosceles trapezoidal box top 120 to restrict the sliding out of the two outermost box plates. The limiting plates 114 are made of Q235 steel plate, 10mm thick, and rectangular in shape.

[0056] Please refer to Figure 1In order to ensure that the top plate of the isosceles trapezoidal box top seat 120 can perfectly fit the bottom surface of the variable cross-section steel box girder and improve the load-bearing stability, the elevation unloading fine adjustment device 100 for the erection and installation of variable cross-section steel box girder provided in this embodiment of the invention has the line shape of the top plate of the isosceles trapezoidal box top seat 120 matching the line shape of the bottom surface of the variable cross-section steel box girder.

[0057] The elevation unloading fine-tuning device 100 for the erection and installation of variable cross-section steel box girders provided in this embodiment of the invention can achieve millimeter-level precise micro-adjustment of height, perfectly adapt to the curved bottom plate line of the variable cross-section steel box girder, meet the line control requirements, and ensure stable load bearing. At the same time, it can achieve synchronous and uniform unloading at multiple points, avoid generating additional stress in the structure, and has the advantages of reliable adjustment and low cost.

[0058] This invention is not limited to the specific embodiments described above. Obviously, the embodiments described above are only a part of the embodiments of this invention, not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of this invention are within the scope of protection of this invention. Those skilled in the art can make other modifications and variations to this invention. Therefore, if these modifications and variations of this invention fall within the scope of the claims of this invention, then this invention also intends to include these modifications and variations.

Claims

1. A device for fine-tuning elevation unloading during the erection and installation of variable cross-section steel box girders, characterized in that, include: An isosceles trapezoidal box-type base, in which the plane containing the longer base of the isosceles trapezoid is arranged horizontally downwards; An isosceles trapezoidal box-type top seat is symmetrically distributed with the isosceles trapezoidal box-type base, with the plane containing the longer base of the isosceles trapezoid facing upwards. The isosceles trapezoidal box-type slide is symmetrically distributed between the isosceles trapezoidal box-type base and the isosceles trapezoidal box-type top seat. The plane containing the longer base of the isosceles trapezoid is arranged vertically on the outer side. The two sides of each isosceles trapezoidal box-type slide are symmetrically slidably arranged on the inclined plane containing the sides of the isosceles trapezoidal box-type base and the inclined plane containing the sides of the isosceles trapezoidal box-type top seat. Tie bolts are horizontally inserted and adjustablely connected to the two isosceles trapezoidal box slides.

2. The elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders according to claim 1, characterized in that, The tie bolt includes a tie rod and nuts connected to both sides, the nuts being located on the outer side of the isosceles trapezoidal box slide on the corresponding side.

3. The elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders according to claim 2, characterized in that, The tie bolt also includes a washer that passes through it.

4. The elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders according to claim 1, characterized in that, The isosceles trapezoidal box base includes a box bottom plate, multiple isosceles trapezoidal box uprights vertically and evenly arranged on the box bottom plate, and inclined lower sloping panels symmetrically arranged on both sides of the box uprights of all the isosceles trapezoidal box bases.

5. The elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders according to claim 4, characterized in that, The isosceles trapezoidal box-type top seat includes a box top plate, multiple isosceles trapezoidal box uprights vertically and evenly arranged on the box top plate, and an upper inclined panel symmetrically arranged on the waist of both sides of the uprights of all the isosceles trapezoidal box-type top seats.

6. The elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders according to claim 5, characterized in that, The isosceles trapezoidal box slide includes a box side plate, multiple isosceles trapezoidal box web plates vertically and evenly arranged on the box side plate, and sliding plates inclined and symmetrically arranged on the waists of both sides of the box web plates of all the isosceles trapezoidal box slides.

7. The elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders according to claim 6, characterized in that, A partition is provided between the adjacent box web plate and the box side plate of the isosceles trapezoidal box slide; a partition is provided between the adjacent box upright plate and the box bottom plate of the isosceles trapezoidal box base; a partition is provided between the adjacent box upright plate and the box top plate of the isosceles trapezoidal box top seat.

8. The elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders according to claim 5, characterized in that, The lower inclined panel of the isosceles trapezoidal box base and the upper inclined panel of the isosceles trapezoidal box top are provided with slots at their inner center to avoid the tie bolts.

9. The elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders according to claim 5, characterized in that, The top profile of the box girder matches the bottom profile of the variable cross-section steel box girder.

10. A method of using the elevation unloading fine-tuning device for the erection and installation of variable cross-section steel box girders according to any one of claims 1-9, characterized in that, Using the isosceles trapezoidal box base as a reference, the variable cross-section steel box girder is erected and installed on the isosceles trapezoidal box top seat. The height of the isosceles trapezoidal box top seat relative to the isosceles trapezoidal box base is adjusted by adjusting the sliding direction of the two isosceles trapezoidal box slides relative to the inclined surfaces of the isosceles trapezoidal box base and the isosceles trapezoidal box top seat through tie bolts.

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