Wind-resistant and anti-seismic suspension bridge structure system suitable for mountainous area and construction method

Abstract

The invention relates to the field of suspension bridge structure engineering, in particular to a wind-resistant and anti-seismic suspension bridge structure system suitable for a mountainous area and a construction method. The combined design of the A-shaped bridge tower, the steel truss girder and the fish-belly-shaped space cable arrangement is adopted, and the fish-belly-shaped space cable arrangement and matched application of the A-shaped bridge tower are adopted, so that the anti-seismic performance can be effectively improved, the displacement of the tower top in the transverse bridge direction is reduced, the stability of the bridge tower is improved, and the internal force geometric nonlinear increasing effect caused by the ultrahigh bridge tower is reduced; the inherent defect that the pneumatic stability is poor due to the ultra-large span and the small width span ratio of the steel truss girder is overcome; meanwhile, the weight of the upper structure is obviously reduced through the light weight of the steel truss girder, and the seismic inertia force acting on the tower, the anchor and the foundation is reduced; in addition, the fusiform cable and the steel truss girder are obliquely connected through the slings, the cable face on the cross section is in an A-shaped change trend, the connection between the main beam and the main cable is increased, the overall transverse bearing capacity of the suspension bridge and the torsional rigidity of the structure are improved, and the wind resistance and safety of the bridge are improved.

Description

Technical Field

[0001] This invention relates to the field of suspension bridge construction technology, and in particular to a wind-resistant and earthquake-resistant suspension bridge structural system and construction method suitable for mountainous areas. Background Technology

[0002] Suspension bridges, as a typical long-span bridge structure, have been widely used in projects spanning rivers and seas. Traditional suspension bridges typically employ a parallel cable system, combined with portal frame towers and steel box girders or steel truss girders as the main beams. The design theory and construction technology for this structural form are relatively mature under normal wind conditions and seismic conditions.

[0003] However, with the rapid development of transportation infrastructure in the mountainous areas of western my country, the spans of suspension bridges are constantly increasing. Especially in mountainous bridges with spans of over 1,000 meters, the environmental conditions they face are significantly different from those in coastal or plain areas. The traditional structural forms of suspension bridges are gradually revealing the following limitations: 1. The structure has a small width-to-span ratio, resulting in insufficient aerodynamic stability. Mountain highways often employ a four-lane design, resulting in limited roadbed width. As the span increases, the width-to-span ratio of the structure decreases significantly. Due to transportation constraints and limited assembly space, the main beams are often single-layer steel truss girders, leading to a lighter overall structure. In complex wind conditions, this type of structure exhibits poor aerodynamic stability, making it prone to flutter, vortex-induced vibrations, and other wind-induced vibrations, thus affecting the bridge's safety and durability.

[0004] 2. Traditional parallel cable systems have poor adaptability to complex wind fields. The wind field in mountainous areas is influenced by topography, exhibiting strong spatial non-uniformity and temporal non-stationarity, with wind attack angle and wind deflection angle varying over a much wider range than in coastal areas. Under non-uniform wind loads, the coupled vibration effect between the cables and the main beam is more pronounced in parallel cable systems, making it difficult to meet the wind resistance requirements of the harsh wind environment in mountainous areas.

[0005] 3. The bridge tower structure is of a single type and has insufficient seismic performance. Traditional parallel cable suspension bridges, with their towers nearly vertical, offer limited options for tower design, currently limited to portal frame structures. This design also has limitations in terms of lateral and longitudinal stiffness distribution. Western mountainous regions experience frequent and intense earthquakes, often exceeding intensity VIII or IX, with a dense distribution of active faults and fracture zones. Portal frame towers are prone to column damage or joint failure under strong earthquakes, making their seismic resistance insufficient for the fortification requirements of high-intensity areas.

[0006] Mountain bridges, subjected to the combined effects of complex wind fields and high-intensity earthquakes, exhibit more complex structural dynamic responses, making it difficult for existing suspension bridge designs to ensure structural safety and reliability under extreme conditions. Therefore, it is necessary to improve the cable system, main girder structure, tower design, and overall structural performance of existing long-span suspension bridges, taking into account the complex wind fields and high-intensity earthquake environments they face. This will enhance their aerodynamic stability and seismic resistance, meeting the specific needs of transportation construction in western mountainous areas. Summary of the Invention

[0007] The purpose of this invention is to address the increasingly prominent limitations of traditional parallel cable systems and portal towers in existing long-span suspension bridges in mountainous areas facing the dual challenges of complex strong winds and high-intensity earthquakes. This invention provides a wind-resistant and earthquake-resistant suspension bridge structure system and construction method suitable for mountainous areas, which can break through the bottlenecks of existing technologies and comprehensively improve the safety, adaptability, and economy of suspension bridges in harsh environments.

[0008] In a first aspect, the present invention provides a wind- and earthquake-resistant suspension bridge structural system suitable for mountainous areas, comprising bridge towers, a cable system and a main beam, wherein the main beam is a steel truss main beam; The bridge towers are vertically located at both ends of the main beam in the longitudinal direction, and the bridge towers are A-shaped cable towers; The cable system includes two sets of main cables. Each set of main cables is connected to the top of the bridge towers on both sides and extends to the anchorage on the corresponding side. The main cables are arranged in a concave shape between the bridge towers on both sides. The transverse spacing between the two sets of main cables gradually decreases from the mid-span to the bridge towers on both sides. The main cables are connected to the main beam through suspenders.

[0009] Preferably, the above-mentioned wind-resistant and earthquake-resistant suspension bridge structural system further includes several pairs of central buckles, which are located at the mid-span of the main span. The two ends of the central buckles are respectively hinged to the main cable and the main beam. The central buckles are energy-dissipating members and are made of buckling-restrained bracing material.

[0010] Preferably, the bridge tower is a steel structure, a reinforced concrete structure, or a steel-concrete composite structure.

[0011] Preferably, the ratio of the lateral spacing Dc between the two main cables at the mid-span to the lateral spacing Dt at the top of the tower satisfies: 5 ≤ Dc / Dt ≤ 9.5.

[0012] Preferably, the above-mentioned wind-resistant and earthquake-resistant suspension bridge structural system further includes a damping device, which is disposed at the connection between the bridge tower and the main beam, and / or at the anchorage between the anchor and the main cable. The damping device is a liquid viscous damper or a limiting seismic device.

[0013] Preferably, the lower deck or truss interior space of the main beam is provided with a passage for laying pipelines or for passage.

[0014] Preferably, the cross-section of the main beam is a truss with vertical web members, a truss with cross web members, or a K-shaped truss.

[0015] Preferably, the upper end of the sling is connected to the main cable using a spatial cable clamp, and the lower end of the sling is connected to the upper chord node or crossbeam of the main beam, so that the main cable, sling, and main beam form a spatial force-bearing system.

[0016] In a second aspect, the present invention provides a construction method applicable to the above-mentioned wind-resistant and earthquake-resistant suspension bridge structural system, comprising the following steps: S1: Construction of the substructure, anchorages, and bridge towers; S2: Install a traction system and cat walkway; S3: Lay the main cable and tighten it; S4: The two sets of main cables are pushed laterally using a horizontal jacking system; S5: Install cable clamps and slings; S6: Erect the main beams in order from the middle of the span towards both banks; S7: Construction of bridge deck system and ancillary structures.

[0017] In a third aspect, the present invention provides a construction method applicable to the above-mentioned wind-resistant and earthquake-resistant suspension bridge structural system, comprising the following steps: S1: Construction of the substructure, anchorages, and bridge towers; S2: Install a traction system and cat walkway; S3: Lay the main cable and tighten it; S4: Install cable clamps and slings; S5: Erecting the main beam: The steel truss main beam is erected in the order of construction from the bridge towers on both banks to the mid-span. The lateral force of the suspenders generated by the weight of the main beam segments is used to naturally spread the two sets of main cables laterally. S6: Construction of bridge deck system and ancillary structures.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a wind- and earthquake-resistant suspension bridge structure system suitable for mountainous areas. It employs a combined design of A-shaped bridge towers, steel truss main beams, and a fish-belly-shaped spatial cable arrangement. By using the fish-belly-shaped spatial cable arrangement in conjunction with the A-shaped bridge towers, compared to the traditional parallel cable H-shaped bridge towers, it effectively improves seismic performance, reduces lateral displacement at the tower top, enhances tower stability, and mitigates the geometrical nonlinear increase in internal forces caused by tower superheight. It also compensates for the inherent aerodynamic instability of steel truss beams due to their large spans and small width-to-span ratios. Furthermore, the A-shaped bridge towers, compared to the rhomboid... Towers of various shapes, such as diamond-shaped ones, offer better seismic performance, stability, and economy, which is beneficial for cost control and project progress of long-span bridges. At the same time, the lightweight steel truss main girder significantly reduces the mass of the superstructure, which helps to reduce the seismic inertial forces acting on the towers, anchors, and foundations. In addition, the shuttle-shaped cable in this design is connected to the steel truss girder by inclined suspension cables, and the cable surface in the cross section presents an A-shaped trend, which helps to increase the connection between the main girder and the main cable, improve the overall lateral bearing capacity and torsional stiffness of the suspension bridge, and thus improve the wind resistance and safety of the bridge. Attached Figure Description

[0019] Figure 1 This is an elevation view of the main cable configuration in Example 1; Figure 2 for Figure 1 Floor plan; Figure 3 A schematic diagram of the standard cross-sectional structure of the main beam; Figure 4 This is a structural schematic diagram of an A-shaped bridge tower; Figure 5 A structural diagram showing the connection point between the main cable and the main beam at the central buckle in the mid-span. Figure 6 This is a schematic diagram of a buckling-restrained brace (BRB). Figure 7 This is a simulated rendering of the main beam being constructed from the bridge tower towards the mid-span.

[0020] Markings in the diagram: 1-bridge tower, 2-main cable, 3-main beam, 4-suspender cable; 5-central buckle. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0022] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0023] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0024] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0025] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0026] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0027] Example 1 like Figures 1-5 , Figure 7 As shown, a wind- and earthquake-resistant suspension bridge structure system suitable for mountainous areas includes a bridge tower 1, a cable system, and a main girder 3. The main girder 3 is a steel truss main girder (referred to as a steel truss girder), the bridge tower 1 is an A-shaped cable tower, and the cable system adopts a spindle-shaped arrangement (or fish-belly shape). The suspension bridge structure system of this embodiment is mainly used in scenarios where the bridge spans long distances across mountainous canyons.

[0028] Tower types used in cable-stayed bridges, such as A-type, rhomboid, and diamond-shaped towers, can all be applied to shuttle-shaped spatial cable suspension bridges. After stress and economic analysis of various tower types, the A-type tower demonstrates significantly better seismic performance and stability than other tower types, and is also more economical. For the bridge type under high-intensity earthquake conditions in this embodiment, the A-type bridge tower option 1 is preferred.

[0029] The A-shaped bridge towers on both sides are built on either side of the canyon. For example... Figure 4 As shown, bridge tower 1 comprises two inwardly inclined columns on the transverse side of the bridge. The columns are arranged in a straight line, gradually converging above the bridge deck and merging at the top. The base or lower part of the tower gradually opens up. The two columns are connected by a crossbeam, forming a laterally stable A-shaped or triangular frame structure. Bridge tower 1 has high lateral stiffness. Its top should have sufficient spacing to anchor the cable system. The inclination angle of the columns is optimized and determined based on the span and wind / seismic conditions. The A-shaped bridge tower 1 can be a steel structure, a reinforced concrete structure, or a steel-concrete composite structure. The A-shaped bridge tower 1 itself has extremely high lateral thrust stiffness, effectively resisting seismic lateral forces.

[0030] like Figure 1 , Figure 2As shown, the cable system includes two sets of main cables 2, which are composed of high-strength steel wire bundles. Each set of main cables 2 starts from an anchorage, passes over the top of the A-shaped bridge tower 1 on one side, extends to the mid-span, and then extends to the top of the bridge tower 1 on the other side and the corresponding anchorage. Along the longitudinal direction of the bridge, the main cable 2 is arranged in a concave shape between the two bridge towers 1. The transverse spacing of the two main cables 2 gradually decreases from the mid-span to the two bridge towers 1, forming a spindle-shaped (or fish-belly-shaped) arrangement in the plane. That is, the main cables 2 gradually approach each other from the mid-span to the bridge tower 1. The transverse spacing in the mid-span area is larger (the suspension cable 4 is the shortest), close to the width of the main beam 3, and the transverse spacing gradually decreases closer to the bridge tower 1 (generally 3-5m considering the construction space and cable saddle arrangement requirements). In this embodiment, the ratio of the transverse spacing Dc of the two main cables 2 in the mid-span to the transverse spacing Dt at the top of the tower is preferably set to meet the condition: 5 ≤ Dc / Dt ≤ 9.5. The opening angle α at the top of the tower is preferably set to 8°-12°. The main cable 2 is connected to the main beam 3 by several suspension cables 4. The suspension cables 4 are spaced along the longitudinal direction of the bridge, and their length gradually increases from the mid-span to the bridge towers 1 on both sides. Furthermore, the upper end of the suspension cable 4 is connected to the main cable 2 by a spatial cable clamp, and the lower end of the suspension cable 4 is connected to the upper chord node or crossbeam of the main beam 3.

[0031] After the main cable 2, suspenders 4, and main girder 3 maintain a three-dimensional spatial equilibrium under their own weight, the projection of the main cable 2 on the plane presents a spindle-shaped (or fish-belly-shaped) arrangement. The upper end of the suspenders 4 is inclined towards the bridge centerline in the cross-section, and the cable surfaces of the left and right suspenders 4 exhibit an A-shaped variation trend. Due to the inclination of the suspenders 4, the connection between the cable and the girder is increased, which greatly improves the lateral bearing capacity and the torsional stiffness of the structure, thereby improving the wind resistance and safety of the bridge. The spindle-shaped main cable 2 and the steel truss main girder are connected by inclination through the suspenders 4, forming a spatial truss torsional system. When the main girder 3 is torsional, the inclination of the suspenders 4 and the spatial cable can generate a strong spatial restoring force, increasing the torsional fundamental frequency and flutter critical wind speed of the structure, effectively suppressing various wind-induced vibrations such as vortex-induced vibration and flutter, and is particularly suitable for turbulent wind fields in mountainous areas.

[0032] like Figure 3 , Figure 5 As shown, the main steel truss beam 3 is a truss structure with an upper chord, a lower chord, and web members, suspended below the cable system by suspenders 4; a Warren-type truss is preferred due to its high transparency. The lower bridge deck or the interior space of the truss of the main beam 3 contains passageways for pipeline installation or passage. The cross-section of the main beam 3 is a truss with vertical web members, a truss with cross web members, or a K-shaped truss.

[0033] In an optional embodiment, the suspension bridge structure system further includes a damping device, which is installed at the connection between the bridge tower 1 and the main beam 3, and / or at the anchorage between the anchor and the main cable 2. The damping device is a liquid viscous damper or a limiting seismic device.

[0034] Furthermore, such as Figure 5 As shown, the above-mentioned suspension bridge structure system also includes several pairs of central buckles 5. The central buckles 5 are set at the mid-span of the main span. The two ends of the central buckles 5 are connected to the main cable 2 and the main beam 3 respectively, which only have translational degrees of freedom and release rotational degrees of freedom. That is, a hinge structure is set in one direction and a joint bearing structure is set in the other direction, so that free rotation can be achieved in both directions. The material of the central buckles 5 is buckling restrained brace (BRB) material, which is semi-rigid. Under normal working conditions, it can play a role in limiting the relative displacement of the cable and beam and improving wind resistance stability. Under strong earthquake action, it can enter the yield state first to dissipate earthquake energy and protect the main cable 2 and the main beam 3 from damage.

[0035] In existing technologies, suspension bridges commonly use two types of central fasteners: rigid central fasteners and flexible central fasteners. Rigid central fasteners typically use box-shaped steel components, with the upper and lower ends fixed to the cable clamps and the main girder, respectively. Under seismic loading, the joints of rigid central fasteners experience significant secondary stresses and may yield. Flexible central fasteners generally incorporate one or more pairs of diagonal suspension cables at mid-span to increase longitudinal restraint between the cable and girder; however, these flexible suspension cables become ineffective under pressure. Neither of the traditional two types of central fasteners provides energy dissipation.

[0036] The semi-rigid central buckle in this scheme is based on the seismic design concept of ductility. It adopts buckling-restrained braces (BRBs) with stable and full hysteretic energy dissipation performance as the main component of the central buckle. It can achieve full-section yielding under tension and compression, thus giving full play to the hysteretic energy dissipation effect of steel. Figure 6 This diagram illustrates the typical structural principle of a buckling-restrained steel brace, consisting of three parts: a core unit, a sliding mechanism unit, and a restraint unit. The core unit dissipates energy by yielding under axial tension and compression. It typically uses steel with a low yield point, allowing it to enter the plastic stage before other structural elements under strong earthquakes, absorbing seismic energy and reducing the risk of damage to the main structure. The restraint unit provides stiffness to resist lateral bending, keeping the core unit approximately under axial stress to enhance its energy dissipation capacity. In essence, "buckling resistance" prevents overall or partial buckling failure of the core brace unit, achieving multi-wave buckling energy dissipation and vibration reduction. The sliding mechanism unit provides a sliding interface and space between the core and restraint units, ensuring similar mechanical properties of the core steel under tension and compression. It also provides adequate deformation space during high-order multi-wave micro-amplitude buckling of the core steel, preventing excessive pressure caused by friction between the core unit and the restraint unit due to compressive expansion. For a semi-rigid central buckle design, please refer to the existing solutions with application numbers 201420639669.0 and 201910312043.6.

[0037] In existing technologies, spatial cable suspension bridges are generally used for short spans. Short-span suspension bridges typically do not have a central buckle; instead, longitudinal viscous dampers are usually installed between the bridge towers and the main girder to mitigate longitudinal displacement of the main girder. This proposed solution, by employing a spatial cable structure and a central buckle in a long-span suspension bridge, effectively suppresses wind-induced vibrations, thereby improving bridge safety and durability.

[0038] The beneficial effects that this plan can produce include: (1) For ultra-long span suspension bridges in mountainous areas, wind-induced vibration, especially flutter stability, is a key factor controlling the design. This scheme adopts a semi-rigid centrally fastened spatial cable steel truss suspension bridge, which improves the aerodynamic coupling effect between the main cable, suspenders and stiffening girder, greatly improves the lateral stiffness and torsional stiffness of the structure, improves the natural vibration characteristics of the structure, and thus improves the wind resistance stability of the suspension bridge. It also greatly improves the flutter problem of steel truss caused by the high turbulence of the wind field in mountainous areas.

[0039] (2) Flutter instability of suspension bridges under wind dynamics mainly manifests as torsional instability or bending-torsional coupling instability. Therefore, its flutter stability mainly depends on the first-order torsional frequency, i.e., the torsional fundamental frequency. The first-order torsional mode of traditional long-span parallel cable suspension bridges is usually symmetrical torsion. Setting a central buckle can only increase the anti-symmetric torsional frequency of the suspension bridge. Therefore, the central buckle has little practical significance in improving the wind resistance stability of parallel cable suspension bridges. However, for suspension bridges with a shuttle-shaped spatial cable system, the torsional fundamental frequency becomes anti-symmetric torsion without a central buckle. Setting a central buckle can increase the anti-symmetric torsional frequency, and the torsional fundamental frequency becomes symmetrical torsion. Therefore, the shuttle-shaped spatial cable and the central buckle have a significant synergistic effect, and their combined use can greatly improve wind resistance stability. Compared with parallel cable suspension bridges of the same structural size, the wind resistance stability can be improved by more than 10%.

[0040] (3) The suspension bridge with a shuttle-shaped spatial cable system adopts A-type bridge towers, which have better seismic performance than H-type bridge towers with parallel cables. It can effectively reduce the transverse displacement of the tower top, improve the stability of the bridge tower, reduce the geometric nonlinear increase effect of internal forces caused by the superheight of the bridge tower, and improve the seismic performance by more than 12%.

[0041] (4) While conventional central buckle installations can enhance the bridge's wind resistance and optimize the tower's seismic response, they can also exacerbate the stress burden on the main girder under seismic loads. This scheme adopts a semi-rigid central buckle structural system, which significantly reduces the secondary bending forces of the main cable and main girder by releasing rotational degrees of freedom. It can also effectively utilize the stress redundancy characteristics of the superstructure, such as the main girder, under seismic action. In the event of a rare earthquake, it can significantly improve the seismic performance of the tower and prevent the main girder from yielding due to excessive stress. By scientifically matching the relationship between the main girder and the tower in terms of seismic response and structural bearing capacity, a reasonable balance between maximizing material efficiency and engineering economy can be achieved.

[0042] (5) In the existing technology, the larger the span and the narrower the bridge width of a suspension bridge, the worse its wind resistance stability, especially its flutter stability. The current solutions usually improve wind resistance by increasing the beam height or beam width, which can easily lead to a significant increase in cost. However, this technology can solve the wind resistance problem without increasing the beam height and beam width by using a shuttle-shaped spatial cable and an A-shaped bridge tower. It breaks through the technical bottlenecks brought about by the wind resistance stability problem and the seismic resistance problem of ultra-large span suspension bridges with a small width-to-span ratio in mountainous areas, and helps the development of suspension bridges in mountainous areas towards larger spans.

[0043] This solution, through the combined application of shuttle-shaped space cables, semi-rigid central buckles, and A-shaped bridge towers, can overcome the technical bottlenecks brought about by the wind stability problem and the seismic resistance problem of suspension bridges with ultra-large spans and small width-to-span ratios in mountainous areas. It can adapt to working conditions with main spans of more than 1,500 meters and width-to-span ratios of 1 / 60 or less, and help the development of suspension bridges in mountainous areas towards larger spans.

[0044] Example 2 Based on Example 1, this example provides a construction method applicable to the above-mentioned wind-resistant and earthquake-resistant suspension bridge structural system, including the following steps: S1: Construction of the substructure, anchorages and bridge towers: Construction of the foundation, piers and anchorage structures is carried out on both banks of the bridge. At the same time, the segmental casting or assembly of the A-shaped bridge towers is carried out simultaneously at the bridge sites on both banks until the top of the tower is reached.

[0045] S2: Erecting the traction system and catwalk: Erecting the traction system includes erecting the pilot cable and the formal traction system. First, a reciprocating pilot cable is erected to form a primary traction system that runs through the entire bridge. The formal traction system (such as main and auxiliary traction winches and circulating steel wire ropes) is then erected using the primary traction system. Subsequently, the formal traction system is used to symmetrically pull and splice the catwalk load-bearing ropes and surface layer from the bridge towers on both banks to the mid-span, completing the catwalk erection and setting up the wind-resistant system.

[0046] S3: Main cable erection and tightening: On the catwalk, the prefabricated parallel wire strands (PPWS) are pulled, erected, adjusted and anchored from one anchorage to the other using the traction system to form the empty cable shape of the main cable; after all strands are erected, the main cable is tightened to achieve the designed shape and density.

[0047] S4: Main Cable Lateral Pushing: A lateral pushing system is used to laterally push two sets of main cables. The lateral pushing system includes a support beam, pushing devices, hydraulic jacks, pushing clamps, ladders, and railings. The hydraulic jacks push the front and rear pushing devices, and the clamps then move the main cables to the outer sides to their spatial alignment. Main cable lateral pushing is existing technology; please refer to patent application number CN201710504417.5 for details, which will not be elaborated here.

[0048] S5: Install cable clamps and slings: Based on the main cable alignment after jacking, measure and lay out to determine the installation position of the cable clamps; install the cable clamps and initially tighten the bolts, while connecting the upper end of the slings to the cable clamps.

[0049] S6: Erecting the main beam segments: The steel truss main beams are erected in a symmetrical and synchronous sequence from the mid-span to both banks.

[0050] S7: Bridge deck construction and final adjustment: Lay bridge deck panels, pour bridge deck paving, and install ancillary facilities; finally tighten the cable clamp bolts and make final adjustments to the cable tension to bring the entire bridge to the designed state.

[0051] S8: Catwalk Demolition and Opening to Traffic: The catwalk will be demolished, a bridge load test will be conducted, and the bridge will be opened to traffic after passing the acceptance test.

[0052] Example 3 Based on Example 1, this example also provides a construction method applicable to the above-mentioned wind-resistant and earthquake-resistant suspension bridge structural system, including the following steps: S1: Construction of the substructure, anchorages and bridge towers: Construction of the foundation, piers and anchorage structures is carried out on both banks of the bridge. At the same time, the segmental casting or assembly of the A-shaped bridge towers is carried out simultaneously at the bridge sites on both banks until the top of the tower is reached.

[0053] S2: Erecting the traction system and catwalk: First, erect the reciprocating pilot cable to form a primary traction system that runs through the entire bridge; then, use the primary traction system to erect the formal traction system (such as main and auxiliary traction winches and circulating wire ropes); subsequently, use the formal traction system to symmetrically pull and splice the catwalk load-bearing ropes and surface layer from the bridge towers on both banks to the mid-span, complete the catwalk erection and set up the wind-resistant system.

[0054] S3: Main cable erection and tightening: Install a cable ring traction system on the catwalk; using the ring traction system, start from the cable laying area behind the anchorages on both banks and pull the prefabricated parallel wire strands (PPWS) to the anchorage on the opposite bank to complete the erection, lateral movement, saddle insertion, anchoring and alignment adjustment of individual strands; erect all strands one by one in the design sequence to form the empty cable alignment of the main cable; after all strands are erected, use a cable tightening machine to tighten the circular cross-section main cable to the design diameter and bundle it.

[0055] S4: Install cable clamps and slings: Based on the measurement and layout of the empty cable alignment, determine the theoretical center position of each cable clamp; transport the cable clamps to the corresponding positions on the catwalk, install them in place using the lifting device, and initially tighten the high-strength bolts; after the main beam is erected to a certain stage, tighten the cable clamp bolts in stages to achieve the design preload; simultaneously connect the upper end of the finished slings to the cable clamps.

[0056] S5: Erection of Main Girder Segments: The steel truss main girder is erected symmetrically and synchronously from the bridge towers on both banks towards the mid-span. The weight of the main girder segments generates a lateral force on the suspenders, which propels the two sets of main cables outward laterally. See also... Figure 7 The main beam construction model shown.

[0057] S6: Construction of bridge deck system and ancillary structures.

[0058] S7: Catwalk Removal and Bridge Commissioning: The catwalks are symmetrically removed from the mid-span to both banks; static and dynamic load tests are conducted on the entire bridge, and the cable force and alignment of the completed bridge are adjusted to the final design state to enable traffic.

[0059] Throughout the construction process, sensors were deployed at key locations (bridge towers, anchorages, main cables, and main beams) to establish a construction monitoring information system. This enabled visualized, information-based, and intelligent monitoring of the entire construction process, ensuring structural safety and precise alignment.

[0060] In step S2 above, when the catwalk is erected, it is preferable to set its alignment lower than that of the main cable. After the catwalk is erected, it is adjusted by a pressing device to make it compatible with the alignment of the main cable erection, so as to facilitate the operation of workers.

[0061] In step S3 above, the strand traction adopts a "double-line reciprocating" traction system, and an anti-torsion device is set during the traction process to ensure that the PPWS strand does not twist or scatter during the traction process.

[0062] Step S5 above specifically includes the following construction steps: S51: Beam segment transportation and lifting: Set up a main beam assembly yard near the bridge towers on both banks to transport the prefabricated steel truss beam segments to the area below the bridge towers; S52: Installation and temporary connection of the first beam segment: Use a bridge deck crane to lift the first main beam segment to the design elevation, and temporarily fix it to the bridge tower crossbeam or embedded parts through temporary connectors; S53: Symmetrical cantilever assembly: Install a bridge deck crane at the front end of the installed main beam segment; transport subsequent beam segments from the erected beam segments to the beam segments to be installed via approach bridges or approach roads on both banks, and match, temporarily connect and finally tighten (or weld) high-strength bolts with the previous segments; at the same time, anchor the lower end of the sling corresponding to this beam segment to the main beam. S54: Cyclic Progression and Alignment Control: Repeat step S53, with the construction teams on both banks symmetrically assembling the main beam segment by segment towards the mid-span; throughout the process, the alignment of the main beam, cable force, and tower deflection are monitored by measurement, and the length of the suspenders or the position of the cable clamps are finely adjusted as needed to ensure that the alignment meets the design requirements; S55: Closure Section Construction: When the cantilever arms on both banks are assembled to the closure point in the middle of the span, the dimensions of the closure point are accurately measured. During the nighttime period when the temperature is stable, the closure section adjustment device is installed to complete the final closure connection.

[0063] After the main beam is closed, the cable tension is adjusted and the temporary tower-beam fixing device is removed to complete the structural system conversion, so that the bridge deck can be laid and the bridge deck pavement, crash barriers, drainage system, lighting and ancillary facilities can be installed.

[0064] During steps S4 and S5, the cable clamp bolts are tightened in three stages: the first stage is when the main beam is erected to about 1 / 4 of its span; the second stage is after the main beam is closed; and the third stage is after the bridge deck is paved to eliminate the influence of structural deformation on the bolt preload.

[0065] In step S53, the bridge deck crane adopts a self-anchored type, and its traveling track is directly laid on the top surface of the upper chord of the installed main beam, using the main beam's own structure as the load-bearing and traveling foundation.

[0066] In this design, the main girder segments are erected from the bridge towers on both banks towards the mid-span. Since the lateral distance between the upper end of the suspenders (main cable location) and the lower end (main girder suspension point) is consistently less than the lateral distance, the lateral force generated by the weight of the main girder segments can be used to naturally propel the upstream and downstream main cables outwards laterally, achieving an effect similar to jacking. This eliminates the need for the lateral jacking step of the main cables, saving on temporary jacking costs. During construction, this method utilizes the existing structure to bear the construction load, eliminating the need for additional large supports, making it highly suitable for canyon terrain.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wind-resistant and earthquake-resistant suspension bridge structure system suitable for mountainous areas, comprising a tower (1), a cable system and a main girder (3), characterized in that, the main girder (3) is a steel truss girder; the tower (1) is vertically arranged at the longitudinal ends of the main girder (3), and the tower (1) is an A-shaped tower; the cable system comprises two groups of main cables (2), each group of main cables (2) is connected with the top of the tower (1) on both sides and extends to the anchorage on the corresponding side, the main cables (2) are arranged in a concave shape between the towers (1) on both sides, the transverse spacing of the two groups of main cables (2) gradually decreases from the midspan to the towers (1) on both sides, the transverse spacing of the two groups of main cables (2) at the midspan is less than or equal to the width of the main girder (3), and the main cables (2) are connected with the main girder (3) by a plurality of hangers (4).

2. The wind and earthquake resistant suspension bridge structural system according to claim 1, wherein, a plurality of pairs of central buckles (5) are further included, the central buckles (5) are arranged at the midspan of the main span, the two ends of the central buckles (5) are respectively hinged with the main cables (2) and the main girder (3), and the central buckles (5) are made of buckling restrained brace material.

3. The wind and earthquake resistant suspension bridge structural system as claimed in claim 1, wherein, The tower (1) is a steel structure, a reinforced concrete structure or a steel-concrete composite structure.

4. The wind and earthquake resistant suspension bridge structural system according to claim 1, wherein, The ratio of the transverse spacing Dc of the two main cables (2) at the midspan to the transverse spacing Dt at the top of the tower satisfies: 5 ≤ Dc / Dt ≤ 9.

5.

5. The wind and earthquake resistant suspension bridge structural system as claimed in claim 1, wherein, A damping device is further included, which is arranged at the connection between the tower (1) and the main girder (3), and / or at the anchoring position of the main cable (2) and the anchorage, and the damping device is a liquid viscous damper or a limited anti-seismic device.

6. The wind and earthquake resistant suspension bridge structural system as claimed in claim 1, wherein, The lower deck or the truss internal space of the main girder (3) is provided with a passage for laying pipelines or passing through.

7. The wind and earthquake resistant suspension bridge structural system according to any one of claims 1-6, wherein, The cross section of the main girder (3) is a truss with vertical web members, a truss with cross web members or a K-shaped truss.

8. The wind and earthquake resistant suspension bridge structural system according to any one of claims 1-6, wherein, The upper end of the hanger (4) is connected with the main cable (2) by a space cable clamp, and the lower end of the hanger (4) is connected with the upper chord node or the cross beam of the main girder (3).

9. A construction method suitable for the wind-resistant and earthquake-resistant suspension bridge structure system according to any one of claims 1 to 8, characterized in that, The steps include: S1: constructing the bridge substructure, anchorage and tower (1); S2: erecting the traction system and catwalk; S3: erecting the main cable (2) and tightening the cable; S4: transversely pushing the two groups of main cables (2) by using a transverse pushing system; S5: installing the cable clamp and hanger (4); S6: erecting the main girder (3) in the order from the midspan to the two banks; S7: constructing the deck system and auxiliary structures.

10. A construction method suitable for the wind-resistant and earthquake-resistant suspension bridge structure system according to any one of claims 1 to 8, characterized in that, The steps include: S1: constructing the bridge substructure, anchorage and tower (1); S2: erecting the traction system and catwalk; S3: erecting the main cable (2) and tightening the cable; S4: installing the cable clamp and hanger (4); S5: erecting the main girder (3): a steel truss girder is erected in the order from the towers (1) on both banks to the midspan, and the two groups of main cables (2) are transversely spread by using the transverse component force of the hanger (4) generated by the weight of the girder segment; S6: constructing the deck system and auxiliary structures.

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