Suspension bridge asymmetric catwalk system and suspension bridge construction method

Abstract

This application relates to an asymmetric catwalk system for suspension bridges and a construction method for suspension bridges. The catwalk system features an asymmetric structure where the width of the space formed between the gantry and the main cable differs on both sides of the transverse bridge. Support cables are installed at the top of the gantry, and multiple load-bearing cables are installed at the bottom. These load-bearing cables are divided into two equal groups, evenly spaced at a first and a second design distance, respectively, also exhibiting an asymmetric arrangement. The longitudinal axis passes through the structural center of gravity of the catwalk surface layer. This longitudinal axis extends in the longitudinal direction of the bridge and passes through the midpoint of the line connecting the centers of all load-bearing cables. This design allows the asymmetry of the load-bearing cables and the asymmetry of the catwalk surface layer to cancel out the eccentric loads, ensuring a smooth catwalk surface and transverse bridge installation. The eccentric load generated during the main cable strand traction is balanced by the transverse bridge. After the catwalk is re-attached, the support cables act as counterweights, offsetting the deflection effect caused by the asymmetry of the catwalk structure relative to the main cable's centerline after re-attachment, thus facilitating construction.

Description

Technical Field

[0001] This application relates to the field of bridge construction technology, and in particular to an asymmetric catwalk system for suspension bridges and a construction method for suspension bridges. Background Technology

[0002] During suspension bridge construction, catwalks are required for tasks such as strand traction, strand adjustment, and cable winding during main cable erection. Conventional catwalk systems employ a symmetrical structure to reduce construction difficulty, especially after catwalk re-hanging, where the symmetrical system has minimal impact on the stress and deformation of the main cable. However, asymmetrical catwalks present certain problems for special bridge types. For example, in a four-cable suspension bridge, when the main cable clearance is small, using a conventional width catwalk can lead to conflicts between adjacent catwalks in the transverse direction. Specifically, adjacent catwalks cannot be installed laterally, or, under the influence of wind in the transverse direction, the small distance between adjacent catwalks makes them prone to collision. Similarly, in cable-stayed suspension bridges, when the distance between the main cable and the stay cables is small, a conventional width catwalk system may interfere with the stay cable installation space.

[0003] Due to the impact of the external environment and interference issues on the catwalk structure, if the conventional symmetrical catwalk design is still followed, the width between the two sides of the main cable centerline and the catwalk gantry needs to be reduced, resulting in a narrow pedestrian walkway and reduced comfort. At the same time, the construction space for the main cable (the space between the main cable centerline and one side of the catwalk gantry) is smaller than the space required for winding and tightening the cable (the space between the main cable centerline and the other side of the catwalk gantry), which does not meet the design requirements. Therefore, it is necessary to consider making an asymmetrical catwalk system. However, an asymmetrical catwalk will have an unbalanced structural stress, and its off-center loading will affect the construction safety and convenience of the catwalk. Summary of the Invention

[0004] This application provides an asymmetric catwalk system for a suspension bridge and a construction method for the suspension bridge, in order to solve the problems of unreasonable stress on the catwalk structure and excessive eccentric load in the related technologies during the catwalk erection process and the main cable traction erection process.

[0005] In a first aspect, an asymmetric catwalk system for suspension bridges is provided, comprising:

[0006] Multiple gantry frames are spaced apart along the longitudinal direction of the bridge; the top of each gantry frame is connected to multiple support cables that extend along the longitudinal direction of the bridge; the bottom of the gantry frame is provided with multiple load-bearing cables that extend along the longitudinal direction of the bridge, and a catwalk surface layer is provided on them.

[0007] The multiple load-bearing cables are divided into two groups, which are located on both sides of the transverse bridge direction, and the number of load-bearing cables in each group is the same; the multiple load-bearing cables in one group are evenly spaced at a first design distance, and the multiple load-bearing cables in the other group are evenly spaced at a second design distance; the second design distance is a design multiple of the first design distance; the longitudinal axis passes through the structural center of gravity of the catwalk surface layer; the longitudinal axis is the longitudinal bridge axis that extends in the longitudinal bridge direction and passes through the midpoint of the line connecting the centers of all load-bearing cables;

[0008] The interior of the gantry is used for the construction of the main cable. During erection, the first space between the gantry on the transverse side of the bridge and the main cable is used to arrange the traction cable strand traction system, and the second space between the gantry on the other transverse side of the bridge and the main cable is used for pedestrian passage. The width of the first space in the transverse direction is greater than the width of the second space in the transverse direction.

[0009] In some embodiments, the arrangement of the traction cable strand traction system includes a strand bracket and a main cable traction device;

[0010] The bottom wall of the first space is provided with a cable support; the top wall of the first space is provided with a main cable traction device.

[0011] In some embodiments, the multiple gantry frames are divided into multiple groups in the transverse direction, with each group of gantry frames corresponding to a main cable;

[0012] A transverse overpass is provided between two adjacent sets of gantry frames.

[0013] In some embodiments, the gantry includes two rectangular frames, one of which is connected to the other on one side in the transverse direction; each rectangular frame has two sets of load-bearing cables at its bottom and support cables at its top.

[0014] Among them, a set of load-bearing cables evenly spaced at a first design distance in the bottom of one rectangular frame is adjacent to a set of load-bearing cables evenly spaced at a first design distance in the bottom of another rectangular frame, and is distributed on both sides of the connecting part; the connecting part is the part where the two rectangular frames are connected.

[0015] In some embodiments, the two rectangular frames are connected by a vibration damper.

[0016] In some embodiments, the multiple support cables are divided into two groups, which are located on both sides of the transverse bridge direction, and the number of support cables in each group is the same; the multiple support cables in each group are evenly spaced at a third design distance.

[0017] In some embodiments, the gantry includes a lower crossbeam and an upper crossbeam; the lower crossbeam and the upper crossbeam are connected by a vertical beam to form a rectangular structure.

[0018] In some embodiments, the top of the upper crossbeam is detachably connected to the top of the vertical beam.

[0019] In some embodiments, the bottom of the upper crossbeam is provided with a first connecting seat, and the first connecting seat is provided with a plurality of connecting holes;

[0020] The top of the vertical beam is provided with a second connecting seat, which has a space to accommodate the first connecting seat and a connecting hole. When the first connecting seat is inserted into the second connecting seat, the fastening bolt passes through the connecting hole to connect the second connecting seat and the first connecting seat.

[0021] Secondly, a method for constructing a suspension bridge is provided, which includes the following steps:

[0022] During the catwalk construction phase, multiple asymmetric catwalk systems of the aforementioned suspension bridge are erected on the suspension bridge. In this step, the first design distance, the second design distance, and the weight of the catwalk surface layer are determined as needed. Then, the load-bearing cables are erected according to the first and second design distances. Finally, the gantry and the catwalk surface layer are erected.

[0023] During the main cable erection phase, when the self-weight of the cable strands causes the traction force of the catwalk system to cause an imbalance in the force on the gantry, the transverse overpass between the asymmetric catwalk systems of adjacent suspension bridges is used for self-balancing.

[0024] During the catwalk re-hanging phase, after the transverse overpass is removed, the connection between the support cable and the top of the gantry is first disconnected, and then connected to the inner bottom wall of the gantry after it is lowered, so as to act as a counterweight to offset the torsional load generated by the asymmetry of the catwalk system relative to the main cable after the re-hanging.

[0025] The beneficial effects of the technical solution provided in this application include:

[0026] This application provides an asymmetric catwalk system for a suspension bridge and a construction method for the suspension bridge. Because it is spaced along the longitudinal direction of the bridge, the top of the gantry is connected to multiple support cables that extend along the longitudinal direction of the bridge; the bottom of the gantry is provided with multiple load-bearing cables that extend along the longitudinal direction of the bridge; the interior of the gantry forms a working space for erecting the main cable; the multiple load-bearing cables are divided into two groups, located on opposite sides of the transverse direction of the bridge, and each group has the same number of load-bearing cables; the multiple load-bearing cables in one group are evenly spaced at a first design distance, while the multiple load-bearing cables in the other group are spaced at... The second design distance is evenly spaced; the second design distance is a design multiple of the first design distance; the longitudinal axis passes through the structural center of gravity of the catwalk surface layer; the longitudinal axis is the longitudinal bridge axis extending in the longitudinal direction and passing through the midpoint of the line connecting the centers of all load-bearing cables; the interior of the gantry is used to install the main cable; during erection, the first space between the gantry on the transverse bridge side and the main cable is used to arrange the traction cable strand traction system, and the second space between the gantry on the other transverse bridge side and the main cable is used for pedestrian passage. The width of the first space in the transverse bridge direction is greater than the width of the second space in the transverse bridge direction. Due to the distribution of the load-bearing cables, the resulting bending moment is offset by the eccentric load caused by the asymmetry of the catwalk surface layer, ensuring the flatness of the catwalk surface layer and the transverse overpass during installation. The eccentric load generated during the traction of the main cable strands is balanced by the transverse overpass. After the catwalk is re-hung, it is hung on the main cable, and the surface layer and load-bearing cables generate an eccentric load effect relative to the centerline of the main cable. At this time, the removed support cables are used as counterweights, improving the actual situation that it is not easy to set external constraints to offset the catwalk after re-hung, and making construction convenient. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 Elevation views of four-main-cable systems with different sags in related technologies;

[0029] Figure 2 This is a schematic diagram of an asymmetric catwalk system for a suspension bridge provided in an embodiment of this application;

[0030] Figure 3 This is a structural schematic diagram of the upper crossbeam provided in an embodiment of this application;

[0031] Figure 4 This is a schematic diagram of the lower crossbeam provided in an embodiment of this application;

[0032] Figure 5 This is a schematic diagram of the remounting process provided in an embodiment of this application;

[0033] Figure 6 This is a schematic diagram showing the removal of the upper horizontal beam and vertical beam as provided in an embodiment of this application.

[0034] In the diagram: 1. Gantry; 100. Lower crossbeam; 101. Upper crossbeam; 102. Vertical beam; 103. First connecting seat; 104. Second connecting seat; 2. Support cable; 3. Load-bearing cable; 4. Main cable; 5. Catwalk handrail cable; 6. Cable strand bracket; 7. Stiffening beam; 8. Re-hanging wire rope; 9. Catwalk surface layer; 10. Main cable traction device. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] refer to Figure 1 This is a schematic diagram of the main cable 4 of a four-main-cable suspension bridge. There are two main cables 4 on each side of the stiffening girder 7. The problems mentioned above in the background art are the problems encountered in the erection of a four-main-cable suspension bridge. However, the above problems also exist in the erection process when the main cable clearance of other suspension bridges is small.

[0037] Therefore, an asymmetric catwalk system and construction method for suspension bridges are proposed to solve the problems of unreasonable stress on the catwalk structure and excessive eccentric load in related technologies when the main cable clearance is small, during the catwalk erection process and the main cable traction erection process.

[0038] See Figures 1-4 An asymmetric catwalk system for a suspension bridge includes multiple gantry frames 1, spaced apart along the longitudinal direction of the bridge. Each gantry frame 1 has multiple support cables 2 connected to its top, extending along the longitudinal direction. The bottom of each gantry frame 1 has multiple load-bearing cables 3, extending along the longitudinal direction, and a catwalk surface layer 9 is provided on top of these cables. The interior of each gantry frame 1 forms a working space for erecting the main cable 4. The load-bearing cables 3 are divided into two groups, located on opposite sides of the transverse direction of the bridge, with each group containing the same number of load-bearing cables 3. In one group, the load-bearing cables 3 are evenly spaced at a first design distance, while in the other group, they are evenly spaced at a second design distance. The second design distance is a design multiple of the first design distance, exhibiting an asymmetric configuration.

[0039] The longitudinal axis passes through the structural center of gravity of the catwalk surface layer 9; the longitudinal axis is the longitudinal bridge axis that extends in the longitudinal direction and passes through the midpoint of the line connecting the centers of all the load-bearing cables 3.

[0040] The interior of gantry 1 is used to house the main cable 4. During erection, the first space between gantry 1 and the main cable 4 on the transverse side of the bridge is used to arrange the traction cable strand traction system, and the second space between gantry 1 and the main cable 4 on the other transverse side of the bridge is used for pedestrian passage. The width of the first space in the transverse direction is greater than the width of the second space in the transverse direction, forming an asymmetrical construction space. Due to the asymmetrical structure of gantry 1, the weight of the catwalk surface layer 9 is unbalanced relative to the vertical centerline of the main cable 4. The weight on both sides of the catwalk surface layer 9 and the spacing of the load-bearing cables 3 are calculated in advance during the design phase to ensure that the center of gravity of the catwalk surface layer 9 and the support center of the load-bearing cables 3 are on the same vertical line, thus ensuring the structural balance of gantry 1.

[0041] The above structure results in an asymmetrical usable space for the gantry 1 and an asymmetrical distribution of stress points on the catwalk surface layer 9. The distribution of the load-bearing cables 3 ensures that the resulting bending moment cancels out the eccentric load caused by the asymmetry of the catwalk surface layer 9, guaranteeing the flatness of the catwalk during installation of the catwalk surface layer and the transverse overpass. The eccentric load generated during the traction of the main cable 4 strands is balanced by the transverse overpass. After the catwalk is re-hung, it is suspended from the main cable 4. The catwalk surface layer 9 and the load-bearing cables 3 experience an eccentric load effect relative to the vertical centerline of the main cable 4. At this time, the removed gantry 1 support cable 2 is used as a counterweight, improving the situation where it is difficult to set external constraints to offset the load after the catwalk is re-hung, and making construction more convenient.

[0042] This solves the problem of unreasonable stress on the catwalk structure and excessive eccentric load in related technologies when the main cable clearance is small, during the catwalk erection process and the main cable traction erection process.

[0043] In some preferred embodiments, the traction cable strand traction system includes a strand bracket 6 and a main cable traction device 10; the strand bracket 6 is provided on the inner bottom wall of the first space; the main cable traction device 10 is provided on the inner top wall of the first space; during erection, one gantry 1 corresponds to one main cable 4, the first space, i.e., the narrow side of the catwalk, is used for main cable erection and wire winding and tightening construction, and the second space, i.e., the wide side of the catwalk, serves as a construction passage for operators, thereby ensuring that the main cable installation space meets the requirements and improving operational comfort. To improve personnel safety, the gantry 1 is equipped with catwalk handrail cables 5.

[0044] In some preferred embodiments, for the construction of conventional main cable erection, multiple gantry frames 1 are divided into multiple groups in the transverse direction, with each group of gantry frames 1 corresponding to a main cable 4; a transverse overpass is provided between two adjacent groups of gantry frames 1.

[0045] For a four-main-cable suspension bridge, refer to Figure 1 Two main cables 4 are installed on each side of the stiffening beam 7 in the transverse direction; during erection, one main cable 4 corresponds to one gantry 1. To avoid transverse conflicts, the following configuration is adopted:

[0046] refer to Figure 2As shown, the gantry 1 includes two rectangular frames, one of which is connected to the other on one side of the transverse bridge direction; each rectangular frame has two sets of load-bearing cables 3 at its bottom, and their distribution, distance, and position are as described above. Support cables 2 are provided at the top;

[0047] Among them, a set of load-bearing cables 3 evenly spaced at a first design distance in the bottom of one rectangular frame is adjacent to a set of load-bearing cables 3 evenly spaced at a first design distance in the bottom of another rectangular frame, and is distributed on both sides of the connecting part; the connecting part is the part where the two rectangular frames are connected.

[0048] Furthermore, the two rectangular frames are connected by a vibration damper, which further reduces the impact of lateral wind.

[0049] In some preferred embodiments, for suspension bridges with a large sag-to-span ratio, the multiple support cables 2 are divided into two groups, which are located on both sides of the transverse direction of the bridge, and the number of support cables 2 in each group is the same; the multiple support cables 2 in each group are evenly distributed at a third design distance.

[0050] The above-mentioned gantry 1 includes a lower crossbeam 100 and an upper crossbeam 101; the lower crossbeam 100 and the upper crossbeam 101 are connected by a vertical beam 102 to form a rectangular structure; the top of the upper crossbeam 101 is detachably connected to the top of the vertical beam 102; the bottom of the upper crossbeam 101 is provided with a first connecting seat 103, and the first connecting seat 103 is provided with multiple connecting holes; the top of the vertical beam 102 is provided with a second connecting seat 104, the second connecting seat 104 is provided with a space to accommodate the first connecting seat 103, and is also provided with connecting holes; when the first connecting seat 103 extends into the second connecting seat 104, the fastening bolt passes through the connecting holes to connect the second connecting seat 104 and the first connecting seat 103.

[0051] Because the top of the upper crossbeam 101 and the vertical beam 102 are detachably connected, dismantling is convenient during the later modification and installation of the catwalk. The support cable 2 can be connected to the lower crossbeam 100. The support cable 2 and the bottom of the upper crossbeam 101 are snapped together, and the load-bearing cable 3 and the lower crossbeam 100 are connected by a U-shaped connector. The lower crossbeam 100 is equipped with a catwalk surface layer. The load-bearing cable 3 is made of high-strength steel wire rope of the same material and with the same cross-section.

[0052] This application also proposes a method for constructing a suspension bridge, which includes the following steps:

[0053] During the catwalk erection phase, multiple asymmetrical catwalk systems are constructed on the suspension bridge. In this step, the first and second design distances, as well as the weight of the catwalk surface layer 9, are determined as needed. Then, the load-bearing cables 3 are erected based on the first and second design distances. Next, the gantry 1 and the catwalk surface layer 9 are erected. The catwalk surface layer 9 slides into place on the load-bearing cables 3 along with the lower crossbeam 100 of the gantry 1. The reason for these steps is that, due to the asymmetrical structure of the gantry, the weight of the catwalk surface layer 9 is unbalanced relative to the centerline of the main cable. Therefore, the weight on both sides of the catwalk surface layer 9 and the spacing of the load-bearing cables 3 are calculated in advance during the design phase to ensure that the center of gravity of the catwalk surface layer 9 and the center of the load-bearing cables 3 are on the same vertical line, thus ensuring the force balance of the gantry structure.

[0054] During the main cable 4 erection stage, when the traction force causes the gantry 1 to be unbalanced, the transverse overpass between the asymmetric catwalk systems of adjacent suspension bridges is used for self-balancing. The main cable strands are arranged on one side, and the traction force will affect the unbalanced force on both sides of the gantry structure. At this time, the self-balancing of the gantry structure is adjusted by the transverse overpass of the catwalk that has been installed.

[0055] During the catwalk re-hanging phase, after the transverse overpass is removed, the connection between the support cable 2 and the top of the gantry 1 is first disconnected, and then, after being lowered, it is connected to the inner bottom wall of the gantry 1. This serves as a counterweight to counteract the torsional load generated by the asymmetry of the catwalk system relative to the main cable 4 after the re-hanging. The reason for this step is that during the catwalk re-hanging phase, the transverse overpass and gantry 1 are removed, leaving only the lower crossbeam 100 of the gantry 1. At this time, by pulling the support cable 2 down to the weaker side as a counterweight, the torsional load generated by the main cable 4 during the re-hanging process can be counteracted. (See reference...) Figure 5 and Figure 6 During the re-hanging process, the outer upper crossbeam 101 is removed, and the support cable 2 is moved to the vicinity of the lower crossbeam 100 and the catwalk handrail cable 5. It is then fixed with a steel structure (i.e., the re-hanging steel wire rope 8) to eliminate the unbalanced moment generated in the catwalk system and reduce the tendency for the catwalk to rotate. The load-bearing cable 3 and the support cable 2 are used as counterweights during the catwalk re-hanging process, which can effectively solve the unbalanced load caused by the asymmetry of the catwalk cross section. At the same time, it improves the actual situation that it is not easy to set external constraints to offset the catwalk after the re-hanging, and realizes quick and convenient construction.

[0056] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0057] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0058] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An asymmetric catwalk system for a suspension bridge, characterized in that, It includes: Multiple gantry frames (1) are spaced apart along the longitudinal direction of the bridge; the top of each gantry frame (1) is connected to multiple support cables (2) which extend along the longitudinal direction of the bridge; the bottom of the gantry frame (1) is provided with multiple load-bearing cables (3) which extend along the longitudinal direction of the bridge and are provided with a catwalk surface layer (9). The multiple load-bearing cables (3) are divided into two groups, which are located on both sides of the transverse bridge direction, and the number of load-bearing cables (3) in each group is the same; the multiple load-bearing cables (3) in one group are evenly spaced at a first design distance, and the multiple load-bearing cables (3) in the other group are evenly spaced at a second design distance; the second design distance is a design multiple of the first design distance; the longitudinal axis passes through the structural centroid of the catwalk surface layer (9); the longitudinal axis is the longitudinal bridge axis that extends in the longitudinal bridge direction and passes through the midpoint of the line connecting the centers of all the load-bearing cables (3); The interior of the gantry (1) is used for the construction of the main cable (4); during erection, the first space between the gantry (1) and the main cable (4) on the side of the gantry (1) in the transverse direction is used to arrange the traction cable strand traction system, and the second space between the gantry (1) and the main cable (4) on the other side of the gantry (1) in the transverse direction is used for pedestrian passage. The width of the first space in the transverse direction is greater than the width of the second space in the transverse direction.

2. The asymmetric catwalk system for suspension bridges as described in claim 1, characterized in that: The arrangement of the traction cable strand traction system includes a cable strand bracket (6) and a main cable traction device (10). The inner bottom wall of the first space is provided with a cable support bracket (6); the inner top wall of the first space is provided with a main cable traction device (10).

3. The asymmetric catwalk system for suspension bridges as described in claim 1, characterized in that: The multiple gantry frames (1) are divided into multiple groups in the transverse direction of the bridge, and each group of gantry frames (1) corresponds to a main cable (4). A transverse overpass is provided between two adjacent sets of gantry frames (1).

4. The asymmetric catwalk system for suspension bridges as described in claim 1, characterized in that: The gantry (1) includes two rectangular frames, one of which is connected to the other on one side in the transverse direction; each rectangular frame has two sets of load-bearing cables (3) at the bottom and support cables (2) at the top. Among them, a set of load-bearing cables (3) evenly spaced at the bottom of one rectangular frame with a first design distance is adjacent to a set of load-bearing cables (3) evenly spaced at the bottom of another rectangular frame with a first design distance, and is distributed on both sides of the connecting part; the connecting part is the part where the two rectangular frames are connected.

5. The asymmetric catwalk system for suspension bridges as described in claim 4, characterized in that: The two rectangular frames are connected by a vibration damper.

6. The asymmetric catwalk system for suspension bridges as described in claim 1, characterized in that: The multiple support cables (2) are divided into two groups, which are located on both sides of the transverse bridge direction, and the number of support cables (2) in each group is the same; the multiple support cables (2) in each group are evenly distributed at the third design distance.

7. The asymmetric catwalk system for suspension bridges as described in claim 1, characterized in that: The gantry (1) includes a lower crossbeam (100) and an upper crossbeam (101); the lower crossbeam (100) and the upper crossbeam (101) are connected by a vertical beam (102) to form a rectangular structure.

8. The asymmetric catwalk system for suspension bridges as described in claim 7, characterized in that: The top of the upper crossbeam (101) is detachably connected to the top of the vertical beam (102).

9. The asymmetric catwalk system for suspension bridges as described in claim 8, characterized in that: The bottom of the upper crossbeam (101) is provided with a first connecting seat (103), and the first connecting seat (103) is provided with multiple connecting holes; The top of the vertical beam (102) is provided with a second connecting seat (104), which has a space to accommodate the first connecting seat (103) and a connecting hole. When the first connecting seat (103) is inserted into the second connecting seat (104), the fastening bolt passes through the connecting hole to connect the second connecting seat (104) and the first connecting seat (103).

10. A method for constructing a suspension bridge, characterized in that, It includes the following steps: During the catwalk erection phase, multiple asymmetric catwalk systems as described in any one of claims 1-9 are erected on the suspension bridge; wherein, in this step, the first design distance, the second design distance and the weight of the catwalk surface layer (9) are first determined as needed, and then the load-bearing cable (3) is erected according to the first design distance and the second design distance; then the gantry (1) and the catwalk surface layer (9) are erected. During the main cable (4) erection stage, when the cable strands’ self-weight causes the catwalk system’s traction force to cause the gantry (1) to be unbalanced, the transverse overpass between the asymmetrical catwalk systems of adjacent suspension bridges is used for self-balancing. During the catwalk re-hanging stage, after the transverse overpass is removed, the connection between the support cable (2) and the top of the gantry (1) is first disconnected, and after it is moved down, it is connected to the inner bottom wall of the gantry (1) as a counterweight to offset the torsional load generated by the catwalk system relative to the main cable (4) after the re-hanging.

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