Folding bridge based on combination of carbon fiber composite material and aluminum alloy corrugated sandwich and erection method of folding bridge

Abstract

The invention belongs to the field of bridges, and particularly relates to a light folding bridge based on combination of a carbon fiber composite material and an aluminum alloy corrugated sandwich and an erecting method of the light folding bridge. Comprising two connectionless rut structures, each rut structure comprises a flat bridge section and two skew bridge sections, the upper portions of the adjacent flat bridge sections and skew bridge sections are in surface connection through top plates, the lower portions of the adjacent flat bridge sections and skew bridge sections are hinged through single-lug and double-lug connection joints, and when the top plates are seamlessly attached, the attaching faces coincide with the vertical face where the axis of a pin shaft between the bridge sections is located; therefore, the folding bridge has a folded state and an unfolded state. The flat bridge section and the inclined bridge section are both of an integrated box type structure, corrugated core adding is adopted for the upper portions of bridge deck slabs and webs, and CFRP is adopted for reinforcing the lower surfaces of the bridge deck slabs and the upper surfaces of the lower flanges of the inverted T-shaped plates. The novel box-type bridge combining the CFRP and the aluminum alloy corrugated sandwich has the advantages of continuous laying of the composite material, no rivet connection, no diaphragm plate, higher integrity and higher lightweight level, and a rapid and convenient erection method is formed.

Description

Technical Field

[0001] The present invention belongs to the field of bridges, and particularly relates to a folding bridge based on a combination of carbon fiber composite materials and aluminum alloy corrugated sandwich cores and an erection method thereof. Background Art

[0002] Problems such as road damage and bridge collapse caused by natural disasters or wars often result in traffic interruption and road blockage, seriously affecting the progress of disaster relief or the arrival of troops at the front line of the battlefield. In order to enable civilian or military equipment to quickly cross obstacles such as ditches and rivers to perform established tasks, emergency support equipment needs to be equipped. The light folding bridge is one of the key equipment for ensuring the mobile deployment of troops and disaster relief. Compared with fixed bridges, such equipment needs to have core characteristics such as lightweight, high strength, modular design, and rapid erection to achieve road carrying capacity. According to the different requirements of application scenarios, rapid portable bridges can be divided into three categories: tactical, support, and traffic line types. Among them, tactical bridges are used to cross obstacles such as ditches and bomb craters within 25m to ensure that troops can reach the front line as soon as possible. At present, the domestic emergency support equipment for crossing obstacles such as ditches, rivers, and bomb craters within 25m mainly uses foldable emergency bridges, mainly including the 84-type tank bridge erection vehicle (push-type folding bridge), 84-type heavy mechanized bridge (scissor-type folding bridge), etc. The domestic foldable emergency bridges are all manufactured by welding steel. Although steel has the advantages of high strength, good plasticity and toughness, uniform stress in all directions, and mature design calculation theory, steel bridges have the disadvantages of large self-weight, poor mobility, and difficulty in meeting the increasingly demanding requirements of current emergency support tasks. Therefore, whether from the perspective of wartime or non-war rescue operations, weight reduction is urgently needed under feasible circumstances.

[0003] At present, the main reasons for the limited structural weight reduction ratio of the existing composite material emergency bridges using the traditional structural scheme of preformed composite material sandwich balsa wood bridge decks, diaphragms, and webs and bottom plates integrated into a composite material thin-walled U-shaped beam and then forming an integral body through secondary bonding and riveting are as follows: 1) Riveting that destroys the continuity of the composite material and causes local stress concentration leads to local crushing of the composite material at the riveting position and delamination failure of the bonding surface, so the high-strength characteristics of the composite material cannot be exerted at all; 2) Although the core layer material with a relatively large weight effectively improves the flexural stiffness of the bridge deck and diaphragm itself and meets the local flexural and shear requirements, its specific stiffness is average. In addition, the diaphragms that control the web instability do not participate in the overall load-bearing, so overall, the contribution to the overall flexural and shear resistance of the structure is low. Summary of the Invention

[0004] The object of the present invention is to provide a lightweight folding bridge composed of a combination of carbon fiber composite material and aluminum alloy corrugated sandwich core, and its erection method, realizing a new box-shaped bridge with CFRP and aluminum alloy corrugated sandwich core that has stronger integrity, higher lightweight level, no rivet connection, no transverse diaphragm, and continuous laying of composite materials, and forming a fast and convenient erection method accordingly.

[0005] The technical solution to achieve the object of the present invention is as follows: A lightweight folding bridge based on the combination of carbon fiber composite material and aluminum alloy corrugated sandwich core includes two unconnected rut structures. Each rut structure includes a flat bridge section and two inclined bridge sections. Both the flat bridge section and the inclined bridge section are integral box-shaped structures. The upper part between adjacent flat bridge sections and inclined bridge sections is connected by the top plate surface, and the lower part is hinged by single and double ear connection joints. When the upper top plates of the bridge sections are seamlessly fitted together, the fitting surface coincides with the vertical plane where the pin axis of the single and double ear connection joints is located, enabling the folding bridge to have two states: folding and unfolding.

[0006] Furthermore, the flat bridge section is a box-shaped structure with a constant cross-section. The inclined bridge section includes an end support springboard section and a variable cross-section box-shaped structure section. The bridge deck inclination angle of the variable cross-section box-shaped structure section is 4.3 ± 0.1°, and the bridge deck inclination angle of the end support springboard section is 11 ± 0.1°, thereby realizing the transition of vehicles from the ground to the middle of the bridge.

[0007] Furthermore, both the flat bridge section and the inclined bridge section are composed of a box-shaped structure main frame welded by a -type corrugated sandwich core member, a thin plate, a "⊥"-type plate, and a bottom plate integrally formed on the upper part. The corrugated sandwich core member is integrally formed by an extrusion welding process. The horizontal section of the -type corrugated sandwich core member is called the bridge deck, and the vertical section of the

[0008] -type corrugated sandwich core member is called the corrugated sandwich web. CFRP is laid on the lower surface of the bridge deck by a vacuum infusion process. A CFRP plate is provided on the lower flange of the "⊥"-type plate through bolts at the end of the bridge section. A plurality of stiffeners are provided transversely on the bottom plate. Sealing plates with through holes are provided at the ends where the bridge sections are connected. A top plate is provided at the upper end where the bridge sections are connected. A transition plate is also included, which is welded to the end web where the bridge sections are connected. A lifting point is provided at the upper outer corner of the transition plate. At one end of the variable cross-section box-shaped structure section of the inclined bridge section close to the springboard, an end sealing plate without a through hole and an anchor plate for bolt-connecting a CFRP plate are provided.

[0009] Furthermore, the bottom plate of the inclined bridge section is continuously and longitudinally arranged at the bottom of the springboard section and the variable cross-section box girder structure section. The "⊥"-shaped plate of the inclined bridge section is continuously and longitudinally arranged on both the left and right sides of the bottom plate. Longitudinal end vertical ribs are welded on the upper surface of the bottom plate of the springboard section, and the end vertical ribs are triangular in shape. Transverse end round tubes are provided at the ends of the end vertical ribs, and wheels are detachably connected to both ends of the end round tubes. End outer webs with multiple holes are provided on the outer sides of the "⊥"-shaped plates in the springboard section, and end bridge decks are provided on the "⊥"-shaped plates and the end vertical ribs in the springboard section. One end of the end bridge deck is welded to the corrugated sandwich component.

[0010] Furthermore, the single / double ear connection joint is used in combination with the single ear connection joint and the double ear connection joint. The structures of the single ear connection joint and the double ear connection joint are the same except for the difference between single and double ears; the single / double ear connection joint includes two horizontal plates, a vertical plate and a single / double ear. The lower flange of the "⊥"-shaped plate and the end of the CFRP plate are inserted between the two horizontal plates of the single / double ear joint and are connected by bolts. The vertical plate and the transition plate are connected by bolts. Relative rotation between the joints is achieved by connecting the single ear and the double ear with a pin shaft.

[0011] A method for erecting the above-mentioned folding bridge includes the following steps:

[0012] Step (1): After transporting the two rut structures in the folded state to the designated location, assemble the wheels on the end round tubes and fix the hooks at the four end lifting points of the flat bridge section;

[0013] Step (2): Fix two towing ropes respectively on the round holes of the outer webs on both sides of the end of the inclined bridge section. One of the placed towing ropes passes through the lifting point, and the other deployed towing rope does not pass through the lifting point;

[0014] Step (3): Lift the hook, gradually lengthen the free end of the placed towing rope, ensure that the inclined bridge section slowly descends during sequential unfolding, and finally reach the state where the flat bridge section is horizontal and the inclined bridge section hangs naturally under its own gravity;

[0015] Step (4): Tighten the four deployed towing ropes to make the inclined bridge section rotate further around the pin shaft, presenting an "eight" shape;

[0016] Step (5): Lower the height of the hook until the wheels at the end of the inclined bridge section touch the ground;

[0017] Step (6): Lower the height of the hook. While tightening the deployed towing ropes, the wheels at the end of the inclined bridge section roll, and the bridge is fully unfolded under its own weight and placed on the flat ground, realizing the unfolding operation of a single rut.

[0018] Step (7): Remove the hooks and fix them at the round holes on the outer webs at the ends of the inclined bridge section of the bridge;

[0019] Step (8): Lift the hook, and at the same time rotate the boom of the crane to the designated location and slowly place it, finally completing the erection operation.

[0020] Compared with the prior art, the remarkable advantages of the present invention are as follows:

[0021] 1. The corrugated sandwich on the bridge deck forms a truss-like structure in the cross-section, which has better transverse bending and shear resistance than the traditional solid-web sandwich panel filled with balsa wood or aluminum foam continuously. As a part of the upper flange of the box girder, the specific stiffness of the aluminum corrugated core layer that participates in the overall bending of the whole cross-section is higher than that of balsa wood. Therefore, the overall stiffness can be improved under the same weight.

[0022] 2. In the existing bridge joint structure, diaphragms are used to improve the stability of the web in a lateral support manner, but they do not participate in the longitudinal overall bending and shear resistance of the beam body. However, the web with a corrugated sandwich on the upper part and a thin plate structure on the lower part adopted in the present invention can not only meet the stability requirements without increasing the weight compared with the original lateral support method of diaphragms, but also the aluminum corrugated sandwich in the web participates in the overall bending and shear resistance of the structure, further improving the structural stiffness and material utilization efficiency.

[0023] 3. The lower surface of the horizontal section of the corrugated sandwich in the bridge span structure is strengthened with CFRP, and the upper part of the left and right lower flanges of the box girder is strengthened with CFRP plates, giving full play to the strength of the carbon fiber material along the fiber direction. It can not only improve the bidirectional bending bearing capacity of the bridge deck under local wheel loads, but also increase the overall bearing capacity of the bridge span structure, achieving the purpose of further reducing the structural weight.

[0024] 4. In the existing emergency bridge, the composite material thin-walled U-shaped beam integrating the bridge deck, diaphragms, web and bottom plate is formed, and then the three are integrated through secondary bonding and riveting. However, in the structural form proposed by the present invention, whether it is the aluminum corrugated sandwich of the bridge deck and the web or the CFRP on the lower surface of the bridge deck, continuous arrangement is realized, without local rivet weakening, etc., effectively avoiding local crushing and delamination failure that are prone to occur in the original composite material bridge under load.

[0025] 5. Without a transverse connection system between the two wheel ruts, it still meets the stability requirements in the traffic state. The widths of the two wheel ruts can be flexibly adjusted according to the actual wheel spacing of the passing vehicles, which can meet the passage of multiple types of vehicles and has stronger applicability.

[0026] 6. Traditional folding emergency bridges need to be equipped with special erection vehicles and erection structures, with high costs. However, due to its light weight, the light folding bridge does not require special erection vehicles and erection mechanisms. Only common small cranes used in civil or military applications and manual assistance control of 8 - 10 people are needed to quickly complete the erection operation, with lower usage costs and greater application flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1Schematic diagram of the unfolded state of the folding bridge of the present invention.

[0028] Figure 2 Schematic diagram of the connection between the upper and lower flanges of the box girder bridge section.

[0029] Figure 3 For Figure 2 Enlarged schematic diagram of the connection joint part of

[0030] Figure 4 Schematic diagram of the composition of the flat bridge section.

[0031] Figure 5 Schematic diagram of the composition of the inclined bridge section.

[0032] Figure 6 Schematic diagram of the cross-section of the flat bridge section.

[0033] Figure 7 Schematic diagram of the cross-section in the middle of the inclined bridge section.

[0034] Figure 8 Schematic diagram of the folded state of the folding bridge.

[0035] Figure 9 Front view of the hoisting of the single rut in the folded state.

[0036] Figure 10 Schematic diagram of the hoisting points and wheel fixation of the single rut.

[0037] Figure 11 Front view of the sequential unfolding process of the single rut inclined bridge section.

[0038] Figure 12 Front view of the natural gravity drooping state of the single rut inclined bridge section.

[0039] Figure 13 Front view of the "eight" shaped unfolded state of the single rut inclined bridge section.

[0040] Figure 14 Front view of the fully unfolded state of the single rut.

[0041] Figure 15 Front view of the hoisting and erection of the single rut.

[0042] Explanation of reference numerals:

[0043] 1 - Flat bridge section, 2 - Inclined bridge section, 3 - Single / double ear connection joint, 4 - Top plate, 5 - Single ear, 6 - Double ear, 7 - Pin shaft, 8 - Horizontal plate, 9 - Vertical plate, 10 - Lower flange of "⊥"-shaped plate, 11 - CFRP plate, 12 - Transition plate, 13 - Corrugated sandwich member, 14 - Thin plate, 15 - Bottom plate, 16 - "⊥"-shaped plate, 17 - Bottom plate stiffener, 18 - Sealing plate, 19 - End sealing plate, 20 - Anchor plate, 21 - End vertical rib, 22 - End circular tube, 23 - End outer web, 24 - End bridge deck, 25 - CFRP layer, 26 - Lifting point, 27 - Bridge deck, 28 - Main girder web, 29 - Hook, 30 - Suspension rope, 31 - Hook, 32 - Wheel, 33 - Place traction rope, 34 - Unfold traction rope. Detailed implementation mode

[0044] The present invention will be further described in detail below with reference to the accompanying drawings.

[0045] As Figures 1-15 shown, the lightweight folding bridge proposed by the present invention, which combines carbon fiber and aluminum alloy corrugated sandwich, is a rut-type single-span structure and includes two rut structures. Each rut structure is longitudinally connected and assembled by three box-type bridge sections, namely one flat bridge section 1 and two inclined bridge sections 2. Between the box-type bridge sections, they are hinged in the form of a pin at the lower end of the bridge section through a single / double ear connection joint 3, and the single / double ear connection joint 3 is connected to the box-type beam bridge section through a bolt group, which is convenient for the folding and retraction of the bridge span;

[0046] The unfolding of the rut structure is realized by the relative rotation of the single / double ear connection joint 3 at the lower end of the box-type bridge section. An aluminum alloy top plate 4 is welded on the aluminum alloy corrugated sandwich member at the upper end of the box-type bridge section. When the top plates are tightly abutted against each other, seamlessly fitted and in frictional contact, and at this time the fitting surface of the top plates coincides with the vertical plane where the axis of the pin shaft 7 is located, the complete unfolding of a single rut is realized. Between the two rut structures of the folding bridge, no transverse connection system is provided. When the folding bridge is in the load-carrying state, the width distance between the two ruts can be adjusted according to the model of the actual load-carrying vehicle, so that there is a certain margin for lateral movement between the left and right bridge sections, improving the actual applicability of the bridge.

[0047] The hinge at the lower part of box - type bridge section 1 or 2 is realized by the pin 7 between the joints. The single - ear and double - ear connection joints include a single - ear 5 or double - ear 6 for hinging, a horizontal plate 8 and a vertical plate 9. The middle of the horizontal plate 8 of the single - ear and double - ear connection joint wraps the lower flange 10 of the "⊥" - shaped plate of the bridge section and the CFRP plate 11, and the three are connected by a group of bolts to achieve their mutual connection. The vertical plate 9 is connected to the transition plate 12 welded on the end web of the bridge section to realize the connection between the single - ear and double - ear connection joint and the web of the bridge section. By setting the vertical plate connected to the transition plate, the single - ear and double - ear connection joint of the present invention enables the force on the single - ear and double - ear to be directly transmitted to the web through the vertical plate on the basis of being transmitted to the aluminum alloy lower flange, avoiding stress concentration at the connection.

[0048] The light - type folding bridge is assembled by six box - type bridge sections. Each box - type bridge section is mainly formed into a box - type cross - section by an integrally - formed aluminum alloy corrugated sandwich member 13 at the upper part, a thin plate 14, a "⊥" - shaped plate 16 and a bottom plate 15. In addition, it includes CFRP 25 on the lower surface of the horizontal section of the aluminum alloy corrugated sandwich member, CFRP plate 11 on the upper part of the lower flange, bottom - plate stiffeners 17, sealing plates 18, top plates 4, transition plates 12, end sealing plates 19, end CFRP reinforcement plates 20, end vertical ribs 21, end round tubes 22, end outer webs 23 and end bridge decks 24. Among them, The corrugated aluminum alloy sandwich member is integrally formed by extrusion and welding processes, and the CFRP is laid on the lower surface of the horizontal section of the corrugated aluminum alloy sandwich member through a vacuum infusion process. The CFRP plates are connected to the lower flange and connection joints by bolts at both ends of the bridge section. The remaining aluminum alloy parts are all connected to each other by welding. According to the structural stress characteristics, the upper horizontal section of the corrugated sandwich member is the bridge deck 27, the lower vertical section of the corrugated aluminum alloy sandwich member is called the corrugated sandwich web, and forms the main - beam web 28 with the vertical plates of the thin plate and the "⊥" - shaped plate.

[0049] Due to the high level of lightweight of the bridge, the bridge has strong applicability in actual erection applications. Compared with using a dedicated bridge - erecting vehicle and erection mechanism, only a small crane and manual assistance are required to complete the erection.

[0050] Specifically, the transport vehicle transports the folded - state bridge to the designated location, and fixes the hook 31 on the lifting rope 30 at the four - end lifting points 26 of the flat bridge section;

[0051] Since the bridge is always in the air during the erection process, the components required for the erection need to be assembled on the bridge in advance. The wheels 32 are fixed to the end circular tubes 22 of the inclined bridge sections of the bridge span structure in advance, and two traction ropes are fixed respectively at the round holes on the outer webs 23 at the left and right ends of the single-wheel rut inclined bridge section. One end of one "placement traction rope" 33 is fixed, passes through the suspension point, and the other end is free. The other "deployment traction rope" 34 does not pass through the suspension point. Manually extend the free end of the "placement traction rope" so that the inclined bridge section slowly descends when it is deployed in sequence, and there will be no phenomenon of rapid descent of the bridge section. Finally, the flat bridge section is horizontal and the inclined bridge section is in a natural hanging state under the condition of gravity. When the inclined bridge section of the bridge is in the natural deployment state, without external force, the two inclined bridge sections of the bridge cannot continue to rotate around the pin shaft on the single and double ear connectors between the bridge sections, and the bridge cannot be fully deployed. Therefore, manually tighten the "deployment traction rope" 34 at both ends of the bridge section until the left and right inclined bridge sections present an "eight" shape, so that the bridge can be smoothly deployed when the subsequent lifting hook descends; slowly lower the height of the lifting hook 29 until the wheels 32 at the end of the inclined bridge section contact the ground;

[0052] Lower the height of the lifting hook. While manually gradually tightening the "deployment traction rope", the wheels 32 at the end of the inclined bridge section roll, and the bridge is gradually deployed and placed on the flat ground, and finally the bridge section deployment operation is completed; Remove the 4 hooks 31 and fix them at the round holes on the outer web 23 at the end of the inclined bridge section of the bridge; Slowly raise the lifting hook 29, and at the same time rotate the boom of the crane to the designated location and slowly place it, and finally complete the single-wheel rut erection operation.

[0053] In summary, the present invention proposes a new box girder structure combining composite materials and aluminum alloy corrugated sandwich cores that realizes continuous laying of composite materials, connection without rivets, no transverse diaphragms, stronger integrity, and higher lightweight level. It provides a feasible solution for the problems of steel bridges, such as large self-weight, poor mobility, and difficulty in meeting the increasingly demanding requirements of mobile support tasks at the present stage.

Claims

1. A folding bridge based on the combination of carbon fiber composite material and aluminum alloy corrugated sandwich core, characterized in that, It includes two non-connected rut mechanisms. Each rut mechanism includes a flat bridge section (1) and two inclined bridge sections (2). The flat bridge section (1) and the inclined bridge section (2) are both integral box structures. The upper surfaces of adjacent flat bridge sections (1) and inclined bridge sections (2) are in surface contact, and the lower parts are hinged through single / double-ear connection joints (3). When the upper surfaces of the bridge sections are in seamless surface contact, the contact surface coincides with the vertical plane where the axis of the pin shaft (7) of the single / double-ear connection joint (3) is located, so that the folding bridge has two states: folding and unfolding.

2. The folding bridge according to claim 1, wherein The flat bridge section (1) is a box structure with an equal cross-section. The inclined bridge section (2) includes an end support springboard and a variable cross-section box structure section. The bridge deck inclination angle of the variable cross-section box structure section is 4.3 ± 0.1°, and the bridge deck inclination angle of the end support springboard is 11 ± 0.1°, so as to realize the transition of the vehicle from the ground to the middle of the bridge.

3. The folding bridge according to claim 2, characterized in that, Both the flat bridge section (1) and the inclined bridge section (2) include a box-shaped structural main frame composed of a -type corrugated sandwich member (13) integrally formed at the upper part, a thin plate (14), a "⊥"-type plate, and a bottom plate (16) welded together. The corrugated sandwich member (13) is integrally formed by extrusion welding. A CFRP layer (25) is laid on the lower surface of the horizontal section of the -type corrugated sandwich member (13) through a vacuum infusion process. A CFRP plate (11) is provided on the lower flange (10) of the "⊥"-type plate through bolts at the end of the bridge section. A plurality of stiffeners (17) are provided transversely on the bottom plate (15). A sealing plate (18) with through holes is provided at the connected end of the bridge sections. A top plate (4) is provided at the upper connected end of the bridge sections. A transition plate (12) is also welded to the web at the connected end of the bridge sections. A lifting point (26) is provided at the upper outer corner of the transition plate (12). At one end of the variable cross-section box-shaped structure section of the inclined bridge section close to the gangplank, an end sealing plate (19) without through holes and an anchoring plate (20) for bolt-connecting the CFRP plate (11) are provided. The corrugated sandwich member (13) is integrally formed by extrusion welding. A CFRP layer (25) is laid on the lower surface of the horizontal section of the -type corrugated sandwich member (13) through a vacuum infusion process. A CFRP plate (11) is provided on the lower flange (10) of the "⊥"-type plate through bolts at the end of the bridge section. A plurality of stiffeners (17) are provided transversely on the bottom plate (15). A sealing plate (18) with through holes is provided at the connected end of the bridge sections. A top plate (4) is provided at the upper connected end of the bridge sections. A transition plate (12) is also welded to the web at the connected end of the bridge sections. A lifting point (26) is provided at the upper outer corner of the transition plate (12). At one end of the variable cross-section box-shaped structure section of the inclined bridge section close to the gangplank, an end sealing plate (19) without through holes and an anchoring plate (20) for bolt-connecting the CFRP plate (11) are provided.

4. The folding bridge according to claim 3, characterized in that, Except for the single- and double-ear connection joints (3), CFRP plates (11), and the materials of other components are all aluminum alloy except for the CFRP layer (25) on the lower surface of the horizontal section of the corrugated sandwich member (13).

5. The folding bridge according to claim 3, characterized in that, The bottom plate (15) of the inclined bridge section is continuously arranged along the entire length at the bottom of the springboard and the variable cross-section box structure section. The "⊥”-shaped plate (16) of the inclined bridge section is continuously arranged along the entire length on the left and right sides of the bottom plate (15). A longitudinal end vertical rib (21) is welded on the upper surface of the bottom plate (15) of the end support springboard. The end vertical rib is triangular in shape. A transverse end round tube (22) is provided at the end of the end vertical rib. The two ends of the end round tube are detachably connected to the wheels (32). An end outer web (23) with a plurality of holes is provided on the outer side of the "⊥”-shaped plate of the springboard. An end bridge deck (24) is provided on the "⊥”-shaped plate (16) of the springboard and the end vertical rib (21). One end of the end bridge deck (24) is welded to the corrugated sandwich member (13).

6. The folding bridge according to claim 5, characterized in that, The single / double-ear connection joint (3) is used in combination with a single-ear connection joint and a double-ear connection joint. The structures of the single-ear connection joint and the double-ear connection joint are the same except for the difference between single and double ears. The single / double-ear connection joint includes two horizontal plates (8), a vertical plate (9) and a single / double ear. The lower flange (10) of the "⊥”-shaped plate and the end of the CFRP plate (11) are inserted between the two horizontal plates (8) and are connected by bolts. The vertical plate (9) and the transition plate (12) are connected by bolts. The relative rotation between the joints is realized by connecting the single ear and the double ear through the pin shaft (7).

7. A method for erecting a folding bridge according to any one of claims 1-6, characterized in that, It includes the following steps: Step (1): After transporting the two rut mechanisms in the folded state to the designated location, assemble the wheels (32) on the end round tubes (22), and fix the hooks at the four-end lifting points (26) of the flat bridge section. Step (2): Fix two traction ropes on the round holes of the outer webs (23) on both sides of the end of the inclined bridge section (1) respectively. One of them, the placed traction rope (33), passes through the lifting point, and the other, the unfolded traction rope (34), does not pass through the lifting point. Step (3): Gradually lengthen the free end of the placed traction rope to ensure that the inclined bridge section slowly descends during successive unfolding, and finally reaches the state where the flat bridge section is horizontal and the inclined bridge section hangs naturally under gravity. Step (4): Tighten the four unfolded traction ropes to make the inclined bridge section further rotate to present an "eight” shape. Step (5): Lower the height of the lifting hook until the wheels (32) at the end of the inclined bridge section contact the ground. Step (6): Lower the hook height. While tightening the deployed towing rope, the wheels at the end of the inclined bridge section roll. The bridge is fully deployed under its own weight and placed on a flat ground to complete the deployment operation of the single rut. Step (7): Remove the hook (31) and fix it at the round hole on the outer web (22) at the end of the inclined bridge section. Step (8): Raise the hook. At the same time, rotate the crane boom to the designated location and slowly place it to finally complete the erection operation.

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