Suspension bridge closure segment installation method

Abstract

This application relates to the field of suspension bridge construction technology, specifically disclosing a method for installing the closure section of a suspension bridge. The method includes first setting up beam yards on both banks of the suspension bridge and using the approach bridges as beam transport channels; erecting a support platform using a scaffolding method; placing the end section steel truss girder onto the support platform using a crane to form a lifting platform; completing the installation of the mid-span and ordinary sections using the lifting platform; and finally completing the installation of the closure section using a counter-tensioning system. The purpose of this patent is to solve the problem that, when using the approach bridges as lifting channels and a scaffolding lifting platform, there is insufficient space under the closure section, requiring pre-offsetting of the end section to complete the closure. It is mainly used for the installation of suspension bridge closure sections.

Description

Technical Field

[0001] This invention relates to the field of suspension bridge construction technology, and in particular to a method for installing the closure section of a suspension bridge. Background Technology

[0002] As a major form of long-span bridge, suspension bridges typically employ segmented hoisting construction for their stiffening girders, ultimately connecting the two girder sections into a single unit via a closure section. The installation accuracy of the closure section is crucial for controlling the bridge's alignment and structural stress state. Achieving precise interface matching under complex main cable alignment variations and temperature influences is a key technical challenge in suspension bridge construction.

[0003] Currently, the installation of suspension bridge closure sections mainly employs the scaffolding method, and the swing-shifting method is also used when site conditions are limited. Due to geographical constraints and environmental requirements, mountain suspension bridges typically use approach bridges as beam transport channels to avoid constructing separate transport routes. However, using approach bridges as beam transport channels requires building a lifting platform on the side of the approach bridge near the mid-span of the main bridge; otherwise, due to the limited travel area of ​​the cable crane, the swing-shifting method must be used to lift the steel beams. For example, the construction method for lifting stiffening girders of suspension bridges using a cross-cable crane with beams, disclosed in patent document CN105839537B, utilizes the approach bridge as a beam transport channel and constructs a lifting platform to complete the steel beam lifting work, but the lifting platform is supported by a cable-stayed structure. The cable-stayed lifting platform requires pre-embedded cable stays, which can cause some damage to the main tower structure, and its reliability needs further verification; at the same time, the cable stays may restrict the space above the lifting platform, therefore a rotating lifting device is used.

[0004] A scaffolded lifting platform remains the mainstream choice. During the closure of the closure section, due to accumulated errors and temperature variations, the closure section may not fit into the space between the lifting platform and the already lifted mid-span. In such cases, the end section above the lifting platform needs to be moved towards the approach bridge. Therefore, how to pre-offset the end section and complete the closure of the closure section is the technical problem that this solution needs to solve. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the technical problem solved by the present invention is that when the approach bridge is used as the lifting channel and a bracket-type lifting platform is adopted, there is not enough space under the closing section, and the steel truss beam at the end section needs to be pre-offset to complete the closing.

[0006] To solve the above problems, the technical solution adopted by the present invention is: a method for installing the closure section of a suspension bridge, comprising the following steps:

[0007] Step 1: Set up beam yards on both sides of the suspension bridge and use the approach bridges as beam transport channels.

[0008] Step 2: The support platform is erected using the scaffolding method. The support platform and the end section of the steel truss girder together form the lifting platform. The top of the support platform scaffolding is equipped with a lifting cylinder to adjust the height of the lifting platform. The cable hoisting system uses non-rotating lifting tools to gradually complete the hoisting and suspension of the mid-span and ordinary sections from the middle of the suspension bridge to both sides.

[0009] Step 3: Lift the closure section using a lifting platform and suspend the steel truss of the closure section on the main cable using temporary slings.

[0010] Step 4: Adjust the end section of the steel truss at the top of the lifting platform to the height corresponding to the permanent hanger anchor point using the lifting cylinder, and complete the connection between the end section of the steel truss and the permanent hanger; the end section of the steel truss is equipped with a counter-pull system near the bottom of the approach bridge, which pulls the end section of the steel truss on the approach bridge side toward the approach bridge side to increase the distance between the end section of the steel truss and the ordinary section of the steel truss.

[0011] Step 5: Remove the temporary slings, lower the closure section steel truss beam using cables, and temporarily hinge the closure section steel truss beam to the adjacent ordinary section steel truss beam.

[0012] Step 6: Use the anti-pull system to move the end section of the steel truss back to the closing section of the steel truss, and finally connect the end section of the steel truss with the closing section of the steel truss to complete the closing.

[0013] Compared with existing technologies, the beneficial effects of this solution are:

[0014] 1. This scheme uses non-rotating lifting equipment for lifting the steel beams. Non-rotating lifting equipment has a simple structure and high reliability. The steel truss has a large transverse span and a large mass of individual segments, making the use of non-rotating lifting equipment for construction even more reliable.

[0015] 2. Since a concrete pavement will eventually be laid on the steel truss, there will typically be a 30-50 cm height difference between the steel truss surface and the approach bridge pavement after the steel truss is connected. During the hoisting process, to eliminate the impact of this height difference on the transportation of the steel truss, the lifting platform's jacking cylinders are used to raise the end section of the steel truss to the same height as the approach bridge pavement. Therefore, when only the closure section of the steel truss remains to be installed, after transferring the end section to a permanent hanger, the lifting platform's jacking cylinders are used again to lower the height of the end section, creating a significant height difference between the end section and the approach bridge. Therefore, by installing jacking cylinders on the lifting platform, the height of the end section can be adjusted as needed, reducing the impact of the height difference between the approach bridge and the lifting platform on the hoisting process.

[0016] 3. This scheme uses non-rotating lifting equipment. The permanent lifting rod would obstruct the lifting of the closure section steel truss, rendering it unusable as a lifting platform. Therefore, this scheme pre-lifts the closure section before connecting the permanent lifting rod at the end, and uses a temporary cable suspender to auxiliaryly suspend the closure section from the main cable to ensure its safety.

[0017] 4. A support-type lifting platform is used, which is structurally stable and highly reliable. Secondly, no temporary beam storage area is provided below the closure section. Temporary beam storage areas are typically used to temporarily store closure sections, but due to insufficient space below the closure section, it is not feasible to set up such an area. Setting up a temporary beam storage area is usually used in scenarios where the approach bridge is not used as a transport channel, such as the scenario disclosed in CN113026563A, "A Suspension Bridge High-Low Displacement Beam Trestle Bridge Steel Beam Lifting Facility and Construction Method Thereof." However, this requires a relatively wide usable space in front of the bridge tower, which is limited or inconvenient to utilize in mountainous areas. Therefore, the approach bridge is chosen as the beam transport channel. Furthermore, using the approach bridge as the beam transport channel reduces the utilization value of the temporary beam storage area, leading to increased costs and construction time.

[0018] Furthermore, the assembly process of the lifting platform is as follows: the first end section of the steel truss girder is transported to the tower column via a 360-degree steerable trolley over the approach bridge. A crane on the approach bridge then hoists the first end section of the steel truss girder onto the chute of the support platform. The second end section of the steel truss girder is then transported to the first end section of the steel truss girder via the trolley over the approach bridge. A crane located on the first end section of the steel truss girder then hoists the second end section of the steel truss girder onto the chute of the support platform. The upper chord of the first and second end sections of the steel truss girder are then hinged together. This assembly of the end section of the steel truss girder and the support platform forms the lifting platform for the subsequent steel truss girder.

[0019] Furthermore, the cable hoisting system is fixed at both ends to the anchorages on both sides of the suspension bridge, the cable support point is located at the top of the tower column, and the cable is suspended above the main cable; a cable crane is installed on the cable, and the cable crane lifts and transports the steel truss girder by cable hoisting.

[0020] Furthermore, four lifting cylinders and multiple temporary supports are evenly distributed on the top of the support platform.

[0021] Furthermore, the anti-tension system controls the distance between the end section steel truss and the closing section steel truss to 30cm. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method of the present invention.

[0023] Figure 2 This is a structural design drawing of the main span of the suspension bridge according to the present invention.

[0024] Figure 3 This is a top view of the support platform of the present invention.

[0025] Figure 4 This is an elevation view of the support platform of the present invention.

[0026] Figure 5 for Figure 4 Schematic diagram of section AA.

[0027] Figure 6 for Figure 4 Schematic diagram of the BB section.

[0028] Figure 7 This diagram illustrates the use of a beam transport trolley to transport and install the end section of the steel truss girder. Figure 1 .

[0029] Figure 8 This diagram illustrates the use of a beam transport trolley to transport and install the end section of the steel truss girder. Figure 2 .

[0030] Figure 9 A schematic diagram showing the lifting platform formed by the supporting platform and the steel truss section at the end.

[0031] Figure 10 A schematic diagram illustrating the use of a cable hoisting system to lift the mid-span steel truss girder.

[0032] Figure 11 This is a schematic diagram of the installation of the steel truss girder in the middle section.

[0033] Figure 12 Schematic diagram of the installation of ordinary steel truss girder Figure 1 .

[0034] Figure 13 Schematic diagram of the installation of ordinary steel truss girder Figure 2 .

[0035] Figure 14 This is a schematic diagram of the installation of the steel truss girder in the closure section.

[0036] The reference numerals in the accompanying drawings include: 1. End section steel truss girder; 2. Mid-span section steel truss girder; 3. Ordinary section steel truss girder; 4. Closing section steel truss girder; 5. Support platform; 51. Lifting cylinder; 52. Slide chute; 53. Bracket; 6. Cable hoisting system; 61. Cable crane; 62. Cable hoist; 63. Cable; 7. Main cable; 71. Permanent suspender; 8. Tower column; 9. Approach bridge. Detailed Implementation

[0037] Figure 1 This is a flowchart of the method of the present invention, which mainly includes the following steps:

[0038] Step 1: Set up beam yards on both sides of the suspension bridge and use the approach bridges as beam transport channels.

[0039] Step 2: The support platform 5 is erected using the bracket method. The support platform 5 and the end section steel truss beam 1 together form a lifting platform. The top of the support platform 5 is equipped with a lifting cylinder 51 to adjust the height of the lifting platform. The cable hoisting system 6 uses non-rotating lifting tools to gradually complete the lifting and suspension of the mid-span and ordinary sections from the middle of the suspension bridge to both sides.

[0040] Step 3: Lift the closure section steel truss girder 4 using a lifting platform, and suspend the closure section steel truss girder 4 from the main cable 7 using temporary slings.

[0041] Step 4: Adjust the end section steel truss 1 at the top of the lifting platform to the height corresponding to the anchor point of the permanent suspender 71 using the lifting cylinder 51, and complete the connection between the end section steel truss 1 and the permanent suspender 71; the end section steel truss 1 is equipped with a counter-pull system near the bottom of the approach bridge, which pulls the end section steel truss on the approach bridge side toward the approach bridge side to increase the distance between the end section steel truss and the ordinary section steel truss.

[0042] Step 5: Remove the temporary slings, lower the closure section steel truss beam 4 using cable hoist 62, and temporarily hinge the closure section steel truss beam 4 to the adjacent ordinary section steel truss beam 3;

[0043] Step 6: Use the anti-pull system to move the end section steel truss 1 back to the closing section steel truss 4, and finally connect the end section steel truss 1 and the closing section steel truss 4 to complete the closing.

[0044] Furthermore, the support platform 5 is erected using the bracket method described in step 2. Specifically, the support platform 5 is erected at the positions of the tower columns 8 on both sides of the suspension bridge. A concrete foundation is poured at the bottom of the support platform 5. The columns are fixedly connected to the concrete foundation by bolts embedded in the concrete foundation. The support platform 5 is a frame structure composed of columns, longitudinal beams, and transverse beams. Vertical scissor bracing is also provided between the columns and the longitudinal and transverse beams. Four lifting cylinders 51 and multiple temporary supports are evenly distributed on the top of the support platform 5.

[0045] Furthermore, the anti-pull system described in step 4 includes a chute 52, in which a roller capable of rotating in both directions is provided, and the roller is connected to an external electrical controller; the chute 52 has lateral limiting devices on both sides, which can limit the lateral displacement of the steel truss beam, so that the steel truss beam can only move back and forth within the chute 52; the chute 52 is set on the rigid support along the longitudinal direction of the bridge, and the rigid support is placed on the corbel 53 of the tower column 8 along the transverse direction of the bridge, and multiple temporary supports are set on the rigid support along the transverse direction of the bridge to transfer the load of the steel truss beam to the support platform 5.

[0046] Further, the specific steps for the support platform 5 and the end section steel truss 1 to jointly form a lifting platform in step 2 are as follows: the end section steel truss 1 numbered J27 is transported to the tower column 8 via a beam transport trolley that can turn 360 degrees, passing through the approach bridge 9. The end section steel truss 1 numbered J27 is then hoisted onto the slide 52 of the support platform 5 by a crane on the approach bridge 9. The end section steel truss 1 numbered J26 is transported to the J27 steel truss via a beam transport trolley, passing through the approach bridge 9. The J26 steel truss is then hoisted onto the slide 52 of the support platform 5 by a crane located on the J27 steel truss. The upper chord of the adjacent side of the J27 steel truss and the J26 steel truss are then hinged together. The end section steel truss 1 and the support platform 5 are combined to form the lifting platform for the subsequent steel truss.

[0047] Furthermore, the cable hoisting system 6 described in step 2 is fixed at both ends to the anchorages on both sides of the suspension bridge, the cable 63 support point is located at the top of the tower column 8, and the cable 63 is suspended above the main cable 7; a cable crane 61 is provided on the cable 63, and the cable crane 61 lifts and transports the steel truss beam through the cable sling 62.

[0048] Furthermore, step 2 involves the gradual lifting and suspension of the mid-span and ordinary sections of the suspension bridge from the middle to both sides, specifically including the following steps:

[0049] A. Hoisting of the mid-span steel truss girder 2: During the hoisting of the mid-span steel truss girder 2, the mid-span steel truss girder 2 is transported to the hoisting platform using a beam transport trolley and connected to the cable crane 62 of the cable crane 61. The cable crane 61 lifts and carries the mid-span steel truss girder 2 to the designed position of the mid-span steel truss girder 2. After the cable crane 61 is fixed, the hoisting system of the cable crane 61 is started to adjust the mid-span steel truss girder 2 to an appropriate height. The mid-span steel truss girder 2 is then transferred from the cable crane 62 of the cable crane 61 to the permanent suspender 71 of the main cable 7 of the suspension bridge, thus completing the hoisting of the mid-span steel truss girder 2.

[0050] B. Hoisting of ordinary steel truss girder 3: After the cable crane 61 completes the hoisting of the mid-span steel truss girder 2, it returns to the hoisting platform unloaded and proceeds to hoist the ordinary steel truss girder 3. The ordinary steel truss girder 3 is hoisted using the same method as the mid-span steel truss girder 2. All ordinary steel truss girder 3 sections from both sides of the mid-span steel truss girder 2 to the two side tower columns 8 are hoisted symmetrically in sequence. During hoisting, after each steel truss girder is connected to the permanent lifting rod 71, the upper chords of adjacent steel truss girder sections are hinged to each other, while the lower chords of the steel truss girder sections are not connected.

[0051] Furthermore, the installation steps for the closure section steel truss girder 4 are as follows:

[0052] A: The closure section steel truss 4 is lifted using a lifting platform and then temporarily suspended from the main cable 7 using slings.

[0053] B: The height of the end section steel truss beam 1 is adjusted by using the lifting cylinder 51 so that the end section steel truss beam 1 reaches the height corresponding to the anchor point of the permanent hanger 71, and the connection between the end section steel truss beam 1 and the permanent hanger 71 is completed, so that the weight of the end section steel truss beam 1 is borne by the permanent hanger 71.

[0054] C: With the help of the anti-pull system, the roller is controlled to rotate in the opposite direction, and the end section steel truss beam 1 placed on the roller of the slide 52 is moved towards the tower column 8, so that the closing distance between the end section steel truss beam 1 and the closing section steel truss beam 4 is controlled at 30cm.

[0055] D: Using the cable hoisting system 6, the closure section steel truss 4 is slowly lowered to the design elevation, and then the permanent suspender 71 on the main cable 7 is connected to the closure section steel truss 4.

[0056] E: After the closure section steel truss beam 4 is connected to the permanent hanger 71, the closure section steel truss beam 4 is hinged to the ordinary section steel truss beam 3.

[0057] F: After the closing section steel truss beam 4 and the ordinary section steel truss beam 3 are hinged, the roller is controlled to rotate in the forward direction by means of the anti-pull system. The end section steel truss beam 1 placed on the roller of the slide groove 52 moves away from the tower column 8, and the closing distance gradually decreases until the upper chord of the closing section steel truss beam 4 and the end section steel truss beam 1 can be hinged.

[0058] The method of the present invention will be further described below through a specific embodiment and in conjunction with the accompanying drawings.

[0059] like Figure 2 As shown: In this embodiment, the main span of the suspension bridge is designed with a total of 55 steel truss sections, of which J0 is the mid-span steel truss section 2, J27, J26 and J27', J26' are the end sections of the suspension bridge 1, J25 and J25' are the closure sections of the steel truss section 4, and J1 to J24 and J1' to J24' are symmetrical ordinary sections of the steel truss section 3.

[0060] The installation sequence of the steel truss is as follows: first, install the end section steel truss 1 on the support platform 5, and use the end section steel truss 1 as a lifting platform; then, lift the mid-span steel truss 2; then, symmetrically lift the ordinary steel trusses on both sides of the mid-span steel truss 2; and finally, lift the closing section steel truss 4.

[0061] Beam yards are set up on both sides of the suspension bridge, and approach bridges are used as beam transport channels.

[0062] Since the present invention adopts a symmetrical hoisting method, beam yards are set up on both sides of the suspension bridge. Therefore, in the following description of specific embodiments, only the construction content of one side of the suspension bridge will be described, and the construction content of the other side of the suspension bridge will not be repeated.

[0063] like Figures 3-6As shown: Support platforms 5 are erected at the positions of the tower columns 8 on both sides of the suspension bridge. The bottom of the support platform 5 is filled with concrete foundation. The columns are fixedly connected to the concrete foundation by bolts embedded in the concrete foundation. The support platform 5 is a frame structure composed of columns, longitudinal beams and transverse beams. Vertical scissor bracing is also provided between the columns and the longitudinal beams and transverse beams. Four lifting cylinders 51 are provided on the top of the support platform 5.

[0064] like Figure 3-6 As shown: The anti-tension system includes a chute 52, within which a roller capable of rotating in both directions is installed, and the roller is externally connected to an electrical controller. Lateral limiting devices are located on both sides of the chute 52 to restrict the lateral displacement of the steel truss, ensuring that the steel truss can only move back and forth within the chute 52. The chute 52 is positioned along the longitudinal direction of the bridge on a rigid support, which is placed along the transverse direction on the corbel 53 of the tower column 8. Multiple temporary supports are installed along the transverse direction on the rigid support to transfer the load of the steel truss to the support platform 5. When the roller in the chute 52 rotates in the reverse direction, the end section of the steel truss 1 placed on the roller in the chute 52 translates towards the tower column 8; conversely, when the roller in the chute 52 rotates in the forward direction, the end section of the steel truss 1 placed on the roller in the chute 52 translates away from the tower column 8.

[0065] like Figures 7-9 As shown: At the start of the hoisting, the end section steel truss girder 1, numbered J27, is first transported to the tower column 8 via the girder transport trolley and approach bridge 9. The J27 section steel truss girder is then hoisted onto the slide 52 of the support platform 5 by the crane on approach bridge 9. The end section steel truss girder 1, numbered J26, is then transported to the J27 steel truss girder via the girder transport trolley and approach bridge 9. The J26 section steel truss girder is then hoisted onto the slide 52 of the support platform 5 by the crane located on the J27 steel truss girder. The upper chord of the adjacent side of the J27 steel truss girder and the J26 steel truss girder are then hinged together. This allows the end section steel truss girder 1 and the support platform 5 to form the hoisting platform for the subsequent steel truss girders.

[0066] like Figure 10 As shown: the cable hoisting system 6 is fixed at both ends to the anchorages on both sides of the suspension bridge, the cable 63 is supported at the top of the tower column 8, and the cable 63 is suspended above the main cable 7; a cable crane 61 is installed on the cable 63, and the cable crane 61 lifts and transports the steel truss girder through the cable sling 62.

[0067] like Figure 10-11As shown: During the hoisting of the mid-span steel truss girder 2, the mid-span steel truss girder 2 is transported to the hoisting platform by a beam transport trolley and connected to the cable crane 62 of the cable crane 61. The cable crane 61 lifts and carries the mid-span steel truss girder 2 to the designed position of the mid-span steel truss girder 2. After the cable crane 61 is fixed, the hoisting system of the cable crane 61 is started to adjust the mid-span steel truss girder 2 to an appropriate height. The mid-span steel truss girder 2 is then transferred from the cable crane 62 of the cable crane 61 to the permanent suspender 71 of the main cable 7 of the suspension bridge, thus completing the hoisting of the mid-span steel truss girder 2.

[0068] like Figure 12-13 As shown: After the cable crane 61 completes the hoisting of the mid-span steel truss 2, it returns to the hoisting platform unloaded and proceeds to hoist the ordinary steel truss 3. The ordinary steel truss 3 is hoisted using the same method as the mid-span steel truss 2, and all ordinary steel truss 3 sections from both sides of the mid-span steel truss 2 to the two side tower columns 8 are hoisted symmetrically in sequence. During hoisting, after each steel truss is connected to the permanent suspender 71, the upper chords of adjacent steel truss sections are hinged to each other, while the lower chords of the steel truss sections are not connected.

[0069] like Figure 14 As shown: The installation steps for the closure section steel truss girder 4 are as follows:

[0070] A lifts the closure section steel truss 4 using a lifting platform and suspends it on the main cable 7 using temporary slings.

[0071] B uses a lifting cylinder 51 to adjust the height of the end section steel truss beam 1 so that the end section steel truss beam 1 reaches the height corresponding to the anchor point of the permanent hanger 71, and completes the connection between the end section steel truss beam 1 and the permanent hanger 71. Then, the lifting cylinder 51 is used to complete the beam lowering step, so that the weight of the end section steel truss beam 1 is borne by the permanent hanger 71.

[0072] C uses a reverse-pull system to control the roller to rotate in the opposite direction. The end section steel truss beam 1, placed on the roller in the slide groove 52, is moved towards the tower column 8, so that the closing distance between the end section steel truss beam 1 and the closing section steel truss beam 4 is controlled at 30cm.

[0073] D. Using the cable hoisting system 6, the closure section steel truss 4 is slowly lowered to the design elevation, and then the permanent suspender 71 on the main cable 7 is connected to the closure section steel truss 4.

[0074] After the E-closing section steel truss beam 4 is connected to the permanent hanger 71, the closing section steel truss beam 4 is hinged to the ordinary section steel truss beam 3.

[0075] After the closure section steel truss beam 4 and the ordinary section steel truss beam 3 are hinged together, the roller is controlled to rotate in the forward direction by means of the anti-pull system. The end section steel truss beam 1 placed on the roller of the slide groove 52 moves away from the tower column 8, and the closure distance gradually decreases until the upper chord of the closure section steel truss beam 4 and the end section steel truss beam 1 can be hinged together.

[0076] In step B of the installation of the closure section steel truss girder 4, after the installation of the slings for end sections J26 and J27 of the steel truss girder 1, the end sections J26 and J27 of the steel truss girder 1 are lowered. Based on the model and stroke of the lifting cylinder 51, the end section steel truss girder 1 of this suspension bridge requires two rotations to be lowered into place. The stroke of the lifting cylinder 51 is 200mm, while the end section steel truss girder of this suspension bridge is 300mm higher than the design elevation; therefore, two rotations are required for correct positioning.

[0077] The specific steps for lowering the beam are as follows:

[0078] Step 1 for lowering the beam: Remove the original first upper pad of the jacking unit;

[0079] Step 2 of lowering the beam: Replace the second upper pad with a plate that is shorter than the first upper pad.

[0080] Step 3 of lowering the beam: Lifting cylinder 51 lifts the beam upwards for pre-tightening;

[0081] Step 4 of lowering the beam: The lifting cylinder 51 lifts the end section of the steel truss beam 1 in sync, and the bottom of the steel truss beam is separated from the temporary support by 10mm. The lifting stops, the lifting cylinder 51 is locked and pressure is maintained, and the lifting force and the displacement of the steel truss beam are monitored in real time during the lifting process.

[0082] Step 5 of lowering the beam: Remove the existing temporary supports;

[0083] Step 6 of lowering the beam: Replace the original temporary supports with support cylinders that are shorter than the temporary supports, and keep them stable;

[0084] Step 7 of lowering the beam: The lifting cylinder 51 returns synchronously, and the load of the steel truss beam is transferred to the support cylinder;

[0085] Step 8 of lowering the beam: Remove the second upper pad on the lifting cylinder 51.

[0086] Step 9 of lowering the beam: Use the lifting cylinder 51 to lift the steel truss beam again. Stop lifting when the bottom of the steel truss beam is 10mm away from all the support cylinders, and lock the lifting cylinder 51 to maintain pressure.

[0087] Step 10 of lowering the beam: Remove the support tube

[0088] Step 11 of lowering the beam: The lifting cylinder 51 synchronously returns oil until all the force on the end section of the steel truss beam 1 is transferred to the permanent hanger.

[0089] At this point, all the upper chords of the steel trusses are hinged to each other, providing temporary lateral connections and maintaining the relative stability of the steel trusses; the lower chords are not connected, preserving the longitudinal degree of freedom of expansion and contraction, and avoiding stress generated inside the structure due to temperature changes or the accumulation of construction errors.

[0090] After the alignment of the main cable 7 is adjusted, the rigid connection of the entire bridge steel truss girder will be carried out.

[0091] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for installing the closure section of a suspension bridge, characterized in that: Includes the following steps: Step 1: Set up beam yards on both sides of the suspension bridge and use the approach bridges as beam transport channels; Step 2: The support platform is erected using the scaffolding method. The support platform and the end section of the steel truss girder together form the lifting platform. The top of the support platform scaffolding is equipped with a lifting cylinder to adjust the height of the lifting platform. The cable hoisting system uses non-rotating lifting tools to gradually complete the lifting and suspension of the mid-span and ordinary sections from the middle of the suspension bridge to both sides. Step 3: Lift the closure section using a lifting platform and suspend the steel truss of the closure section from the main cable using temporary slings; Step 4: Adjust the end section of the steel truss at the top of the lifting platform to the height corresponding to the permanent hanger anchor point using the lifting cylinder, and complete the connection between the end section of the steel truss and the permanent hanger; the end section of the steel truss is equipped with a counter-pull system near the bottom of the approach bridge to pull the end section of the steel truss on the approach bridge side toward the approach bridge side, so as to increase the distance between the end section of the steel truss and the ordinary section of the steel truss. Step 5: Remove the temporary slings, lower the closure section steel truss beam using cables, and temporarily hinge the closure section steel truss beam to the adjacent ordinary section steel truss beam; Step 6: Use the anti-pull system to move the end section of the steel truss back to the closing section of the steel truss, and finally connect the end section of the steel truss with the closing section of the steel truss to complete the closing.

2. The method for installing the closure section of a suspension bridge according to claim 1, characterized in that: The lifting platform is assembled as follows: the first end section of the steel truss is transported to the tower column via a beam transport trolley over the approach bridge; a crane on the approach bridge then lifts the first end section of the steel truss onto the slide of the support platform. The second end section of the steel truss is transported to the first end section of the steel truss via a beam transport trolley over the approach bridge; a crane located on the first end section of the steel truss then lifts the second end section of the steel truss onto the slide of the support platform. The upper chord of the first and second end sections of the steel truss are then hinged together. The end sections of the steel truss and the support platform are combined to form the lifting platform for the subsequent steel trusses.

3. The method for installing the closure section of a suspension bridge according to claim 1, characterized in that: The cable hoisting system is fixed at both ends to the anchorages on both sides of the suspension bridge, with the cable support point located at the top of the tower column and the cable suspended above the main cable; a cable crane is installed on the cable, which lifts and transports the steel truss girder by cable hoisting.

4. The method for installing the closure section of a suspension bridge according to claim 2, characterized in that: The beam transport trolley can turn 360 degrees.

5. The method for installing the closure section of a suspension bridge according to claim 1, characterized in that: The top of the support platform has four lifting cylinders and multiple temporary supports evenly distributed.

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