Straddle type sling installation method

Abstract

The invention discloses a straddle type sling mounting method, which comprises the following steps of: dragging a zenith trolley to a preset area by utilizing a main tower top traction winch, hoisting an upper-section sling to a position above a catwalk through an adjacent tower crane, connecting a connecting plate at the lower end of the upper-section sling with a chain block on the zenith trolley, and hoisting the upper-section sling to the position above the catwalk through a main tower crane; transferring the upper-section sling from the tower crane to the chain block; driving the zenith trolley to carry the upper-section sling to move at a constant speed along the main cable to a preset mounting position; the lower end of the sling is pulled through a sliding rope, and a chain block is matched for regulation and control, so that the upper-section sling naturally droops around the notch of the sling clamp until the central point coincides with the zenith line of the sling clamp; repeating the steps to complete the installation of the full-bridge upper-section sling; after the catwalk is changed to be hung on the main cable, the lower-section sling and the upper-section sling are connected in a fastened mode; the stiffening beam is hoisted, the lower ends of the slings are anchored, and the beam falls slowly to enable the slings to be stressed step by step. Through mutual cooperation of the installation method and the fixing device, the risk that the cable clamp and the sling slip relative to each other is avoided, and the installation method is suitable for construction of suspension bridges of various straddle type slings.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology, and more specifically, relates to a method for installing straddle-type suspension cables. Background Technology

[0002] In suspension bridge construction, straddle-type suspenders are widely used due to their structural characteristics, but their installation accuracy directly affects the overall structural stability and service safety of the bridge. However, in actual construction, straddle-type suspenders commonly suffer from uneven stress on both sides, leading to cable clamp twisting, which severely restricts installation quality and poses potential risks to bridge structural safety.

[0003] Analysis revealed that the insufficient installation accuracy of straddle-type suspension cables stemmed primarily from two core issues in different scenarios: First, for parallel cable suspension bridges, when the stiffening girder is hoisted after the suspension cables are installed, there is a difference in the timing of the force applied to the cables on both sides. This difference in the timing of the force application directly causes the cable clamps to twist, compromising the alignment accuracy of the suspension cable installation. Second, for spatial cable suspension bridges, the cable clamps are usually pre-set with a certain lateral deflection angle. After the suspension cables are installed but before the stiffening girder is hoisted, the suspension cables will naturally be in a vertical state, causing the center point of the suspension cables to deviate from the zenith line of the cable clamps. During the girder hoisting process, the suspension cables are subjected to force, and the tension on both sides of the suspension cables is redistributed, which in turn induces the main cable to twist, affecting the overall structural alignment.

[0004] Existing construction techniques largely rely on the experience of construction personnel or control the torsion of cable clamps and the offset of slings by pre-reserving offset. However, the torsion angle of cable clamps is affected by multiple factors such as the beam dropping speed, the designed deflection angle of cable clamps, and the length of slings. Experience-based control and fixed offset reservation are difficult to adapt to complex construction conditions and cannot accurately offset the deviations caused by various variables. Ultimately, the problem of substandard installation accuracy still exists. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a straddle-type sling installation method. The upper sling installation uses alignment of the marked point with the zenith line of the sling clamp as a reference, supplemented by hand-operated hoists for directional fine-tuning of deviations, replacing traditional estimation methods. This effectively ensures alignment accuracy and avoids stress concentration caused by deviations. A zenith trolley is used for sliding transport, with manual traction in gentle sections to prevent the sling from rubbing against the catwalk or main cable. After installation, a dedicated fixing device limits the sling's position, preventing slippage within the sling clamp groove. The lower sling installation method is selected based on length differences, with 10m as the dividing line. Lower slings not exceeding 10m lengths utilize a double zenith trolley system. The traction and steering wheels are lowered in a directional manner, and the connection is completed after the front and rear hand-operated hoists are used for graded attitude adjustment, avoiding the problem of sagging and torsion caused by its own weight. The lower section of the sling, which is longer than 10m, is lifted vertically by a winch and the force conversion and attitude adjustment are completed by the cable clamp hand-operated hoist. The steps are simple and the equipment investment is small. The fixing device relies on the collaborative structure of "sling clamp + sling liner + anchor bolt" to achieve axial rigid limit of the upper section of the sling, resist the slippage and imbalance caused by load transfer, and the liner buffers the compressive stress and protects the sling body. It is suitable for all construction conditions and can be easily removed after the force system is converted, so as to achieve smooth and unified temporary limit and process connection.

[0006] To achieve the above objectives, a straddle-type sling installation method according to the present invention includes the following steps: S100: Using a traction winch located at the top of the main tower, the zenith trolley is pulled to a predetermined area at the top of the main tower. The upper section of the sling is lifted by a tower crane located near the main tower and positioned above the catwalk. The connecting plate connected to the lower anchor of the upper section of the sling is connected to the hand chain hoist on the zenith trolley. The tower crane is operated to slowly lower the upper section of the sling while the hand chain hoist is operated to pull the upper section of the sling upward. Once the upper section of the sling is vertical and stable, the connection between the tower crane and the upper section of the sling is released, so that the upper section of the sling is vertically suspended above the catwalk. S200: Start the traction winch at the top of the main tower. Through the winch's uniform rope release action, drive the zenith trolley to move along the main cable direction with the upper section of the sling until the upper section of the sling is transported to the pre-designed installation position. S300: The construction workers connect the guide rope to the lower end anchor head of the upper section of the sling. By manually pulling the guide rope, the lower end of the upper section of the sling is pulled around the groove of the cable clamp. At the same time, the hand-operated hoist is lowered so that the upper section of the sling hangs down naturally under its own weight. The spatial posture of the sling is adjusted until the central axis of the upper section of the sling coincides with the zenith line of the cable clamp. S400: Repeat steps S100 to S300 to complete the installation of all upper section slings of the entire bridge in sequence; S500: The catwalk is re-suspended on the main cable, and the upper end of the lower sling is fastened to the connecting plate at the bottom of the upper sling according to the preset construction sequence. S600: The stiffening beam is hoisted to a preset position higher than the design elevation. The lower end anchor of the lower section of the sling is anchored to the lifting lug on the stiffening beam. The hoisting equipment is controlled to drive the stiffening beam to slowly lower, so that the sling gradually bears the load of the stiffening beam, and the force system of the sling is transformed.

[0007] Furthermore, in step S100, after the zenith trolley is pulled to the preset area at the top of the main tower, the zenith trolley is fixedly connected to the catwalk load-bearing beam by a limiting device. The limiting device includes a hand-operated hoist and a steel wire rope. The two ends of the hand-operated hoist are fixedly connected to the zenith trolley and the catwalk load-bearing beam by steel wire ropes, respectively, thereby limiting the risk of the zenith trolley tilting or overturning during the upper sling hoisting operation and ensuring the stability and safety of the hoisting operation.

[0008] Furthermore, in step S200, when the zenith trolley slides to a section of the main cable with a gentle slope and cannot slide autonomously due to insufficient gravity, the zenith trolley is driven to move towards the middle of the main cable span by manual traction until the upper section of the suspender is accurately delivered to the corresponding clamp installation position.

[0009] Furthermore, during the manufacturing stage, a marker point A is marked at the preset center position of the upper section sling. After the upper section sling is transported to the construction site, marker points B and C are marked on both sides of the reference marker point A, and the marker points B and C are symmetrically arranged relative to the reference marker point A.

[0010] Furthermore, step S300 specifically includes the following steps: S310: After the zenith trolley is transported to the preset installation position with the upper section of the sling, the zenith trolley is fixedly connected to the catwalk load-bearing beam by the limiting device to restrict the displacement and overturning tendency of the zenith trolley. S320: The construction workers connect the guide rope to the lower anchor head of the upper sling. By manually pulling the guide rope, the lower end of the upper sling is pulled around the groove of the cable clamp. At the same time, the hand-operated hoist is lowered so that the upper sling hangs down naturally under its own weight. After the mark point A of the upper sling is aligned with the zenith line of the cable clamp, the upper sling and the cable clamp are temporarily anchored with slings to prevent the sling from shifting. S330: Transfer the fixing device to the installation position. The fixing device includes a sling clamp, anchor bolts, and a sling liner. First, assemble the sling liner at the symmetrical marking points B and C of the upper sling. Then, clamp the sling clamp at the location of the sling liner to secure the upper sling and prevent axial slippage. Next, fasten the anchor head at one end of the upper sling to the connecting plate at the other end of the anchor head. Finally, release the temporary anchoring measures. S340: Observe the overlap between the mark point A of the upper sling and the zenith line of the cable clamp. If there is a deviation, use a hand-operated hoist to fine-tune the spatial posture of the upper sling until the mark point A and the zenith line of the cable clamp are completely overlapped. Then fix the sling clamp with anchor bolts. S350: If the mark point A of the upper sling shifts to the left, then assemble the hand chain hoist on the right side of the sling clamp and connect it to the upper sling through a soft sling. Operate the hand chain hoist to pull and adjust the sling. If the mark point A of the upper sling shifts to the right, then assemble the hand chain hoist on the left side of the sling clamp and connect it to the upper sling through a soft sling. Operate the hand chain hoist to pull and adjust the sling until the mark point A precisely coincides with the zenith line of the sling clamp.

[0011] Furthermore, in step S500, when the length of the lower sling is less than or equal to 10m, the following steps are specifically included: A tower crane is used to hoist the lower section of the sling to the working plane of the catwalk. Two zenith trolleys are installed on the gantry load-bearing cable. Two traction winches are installed at the top of the main tower. The traction winches are connected to the two zenith trolleys one by one by steel wire rope. The bottom of each zenith trolley is equipped with a hand chain hoist. The zenith trolley is pulled to the vicinity of the main tower by the traction winches. Then, the two zenith trolleys are fixedly connected to the catwalk load-bearing crossbeam by the limiting device. First, connect the hand-operated hoist on the trolley at the front end to the lower anchor head of the lower sling. Drive the lower end of the lower sling upwards through the hand-operated hoist, and simultaneously control the tower crane to lower the other end of the lower sling to the preset position. Then connect the hand-operated hoist on the trolley at the rear end to that end of the lower sling. After completing the connection, disconnect the steel wire rope of the tower crane from the lower sling. Start the two traction winches at the top of the main tower, and drive the two zenith trolleys to move the lower section of the sling along the gantry load-bearing cable at a uniform speed to deliver the lower section of the sling to the designed installation position. Set up a steering wheel on the catwalk directly below the cable clamp, adjust the hand chain hoist on the front zenith trolley, drive the lower section of the sling to descend and pass it through the steering wheel, disconnect the front hand chain hoist from the lower section of the sling, and slowly move the rear zenith trolley towards the cable clamp so that the lower section of the sling is oriented and lowered smoothly along the steering wheel; After the rear zenith trolley moves to a position directly above the cable clamp, the lower section of the sling is slowly lowered using a hand-operated hoist on the rear zenith trolley. When the upper end of the lower section of the sling is close to the catwalk surface, a hand-operated hoist is temporarily installed on the cable clamp. The hand-operated hoist is connected to the upper anchor head of the lower section of the sling via a soft sling. The connection between the lower section of the sling and the hand-operated hoist on the rear zenith trolley is then released. The hand-operated hoist on the cable clamp is then manipulated to slowly lower the lower section of the sling to the height required to align the mounting hole of the upper anchor head with the mounting hole of the bottom connecting plate of the upper section of the sling. The lower section of the sling is then securely connected to the connecting plate using a pin.

[0012] Furthermore, after the two zenith trolleys are towed to the preset area at the top of the main tower, the two zenith trolleys are fixedly connected to the catwalk load-bearing beams by limiting devices. After the two zenith trolleys, carrying the upper section of the sling, are transported to the preset installation position, the zenith trolleys are fixedly connected to the catwalk load-bearing beam using a limiting device.

[0013] Furthermore, in step S500, when the length of the lower sling is greater than 10m, the following steps are specifically included: The lower section of the sling is transported to the location directly below the preset installation position. A steering wheel is then installed directly below the sling clamp corresponding to the installation position. The wire rope of the main tower top traction winch is wound around the steering wheel and lowered to the location of the lower section of the sling. The wire rope is connected to the end of the lower section of the sling through a soft sling. The traction winch is started and the wire rope is wound up at a uniform speed. The lower section of the sling is gradually pulled upward in the vertical direction by the traction force of the wire rope. When the upper anchor head of the lower sling is about to approach the connecting plate at the bottom of the upper sling, install a hand-operated hoist on the cable clamp, connect the hand-operated hoist to the upper anchor head of the lower sling, disconnect the lower sling from the steel wire rope of the tower top traction winch, and realize the transfer of the force system of the lower sling from the winch steel wire rope to the hand-operated hoist on the cable clamp. Adjust the spatial position and posture of the upper anchor head of the lower sling by using the hand-operated hoist on the cable clamp, so that the pin hole of the upper anchor head of the lower sling is coaxially aligned with the pin hole of the bottom connecting plate of the upper sling. Insert the pin into the aligned pin hole to complete the fastening connection between the lower and upper slings.

[0014] Furthermore, when installing the lower section of the suspenders at the cable clamps in the vicinity of the main tower, the lower section of the suspenders is placed on the top surface of the steel box girder or the top surface of the steel platform. For the lower section of the suspenders to be installed in other areas, transport vessels are used to transport them to the water position directly below the corresponding cable clamp.

[0015] Furthermore, before the installation of the lower section of the sling, according to the construction process requirements, a hoisting through hole is opened at the corresponding position of the catwalk mesh directly below the sling clamp. After the installation of the lower section of the sling is completed, the hoisting through hole is protected by a guardrail or by a safety net. The upper end of the safety net is fixedly connected to the sling clamp, and the lower end is fastened to the catwalk mesh.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The present invention provides a straddle-type sling installation method, which uses the alignment of the marked point with the zenith line of the sling clamp as a reference, and uses a hand-operated hoist to finely adjust the deviation, replacing the traditional estimation method. This effectively ensures the alignment accuracy of the upper sling and avoids stress concentration caused by deviation. A zenith trolley is used for sliding transportation, and manual traction is used in flat sections to prevent the sling from scraping against the catwalk and main cable. After installation, the sling is limited by a fixing device to prevent it from slipping in the sling clamp groove.

[0017] 2. This invention provides a straddle-type sling installation method. By selecting the installation method for the lower sling based on its length, it adapts to the construction characteristics of slings of different lengths, balancing installation accuracy and efficiency. For lower slings no longer than 10m, a double-zenith trolley is used for coordinated traction and transportation. After being lowered directionally by a steering wheel, the sling's posture is adjusted in stages using front and rear hand-operated hoists, and then the force conversion and precise docking are completed. This multi-step coordinated control effectively avoids sagging and torsion problems caused by the weight of long slings, ensuring the integrity of the sling and the stability of the installation. For lower slings shorter than 10m, a winch is used for traction and vertical lifting around the steering wheel. Then, a cable clamp hand-operated hoist completes the force conversion and anchor head posture fine-tuning, directly achieving docking with the upper sling. The steps are simple, the equipment investment is small, and multiple equipment coordination is not required, significantly improving the installation efficiency of short slings. The differentiated step design precisely matches the construction needs of lower slings of different lengths, uniformly ensuring the docking accuracy of the upper and lower slings.

[0018] 3. The present invention provides a straddle-type sling installation method, which relies on the synergistic structure of "sling clamp + sling liner + anchor bolt" through a fixing device. The clamp and anchor bolt form a rigid clamping structure, which reliably limits the axial movement of both ends of the upper sling, effectively resisting the axial slippage of the sling caused by the load transfer during the stiffening beam hoisting stage, and eliminating the problem of one end being tight and the other loose due to force imbalance. The built-in sling liner can buffer the compressive stress between the clamp and the sling body, avoiding damage to the sling body due to clamping or friction, while enhancing clamping stability and ensuring the integrity of the sling structure. The device is adaptable to all construction conditions, can stably bear load after the sling is centered and fixed, and can be easily removed after the sling force system is converted, achieving smooth and unified temporary limiting and process connection. Attached Figure Description

[0019] Figure 1This is a schematic flowchart of a straddle-type sling installation method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the installation of a limiting device in a straddle-type sling installation method according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the upper section of the sling being hoisted according to an embodiment of the present invention for a straddle-type sling installation method; Figure 4 This is a schematic diagram of the auxiliary installation of the upper section of the sling rope in an embodiment of the present invention for a straddle-type sling installation method; Figure 5 This is a schematic diagram showing the completion of the upper section of the sling installation in an embodiment of the straddle-type sling installation method of the present invention; Figure 6 This is a schematic diagram of the cross-section of the lower section of the sling, which is no more than 10m long, in an embodiment of the present invention for a straddle-type sling installation method. Figure 7 This is a schematic diagram of the longitudinal section of the lower section of the sling, which is no more than 10m long, in an embodiment of the present invention for a straddle-type sling installation method. Figure 8 This is a schematic diagram of the steering wheel installation in a straddle-type sling installation method according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the lower section of the sling with a length not exceeding 10m, as described in an embodiment of the present invention for a straddle-type sling installation method. Figure 10 This is a schematic diagram of the connection between the lower and upper sections of a straddle-type sling installation method, with a length not exceeding 10m, according to an embodiment of the present invention. Figure 11 This is a schematic diagram of the lower section of the sling with a length greater than 10m, as described in an embodiment of the present invention for the installation of a straddle-type sling. Figure 12 This is a schematic diagram illustrating the conversion of the lower section of the sling, which is longer than 10m, in an embodiment of the present invention for a straddle-type sling installation method. Figure 13 This is a schematic diagram of the connection between the lower and upper sections of a straddle-type sling installation method according to an embodiment of the present invention, where the length of the lower sling is greater than 10m. Figure 14 This is a schematic diagram of the upper section of the sling marking point in a straddle-type sling installation method according to an embodiment of the present invention; Figure 15 This is a structural diagram of a fixing device for a straddle-type sling installation method according to an embodiment of the present invention; Figure 16 This is a schematic diagram of the fixing device installation of a straddle-type sling installation method according to an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0022] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] In this patent, the terms "comprising," "including," or any other variations thereof are intended to cover a 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 limitation, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0024] Example 1 like Figure 1-16 As shown, this embodiment of the invention provides a method for installing a straddle-type sling, including the following steps: S100: Using a traction winch located at the top of the main tower, the zenith trolley is pulled to a predetermined area at the top of the main tower. The upper section of the sling is lifted by a tower crane located near the main tower and positioned above the catwalk. The connecting plate connected to the lower anchor of the upper section of the sling is connected to the hand chain hoist on the zenith trolley. The tower crane is operated to slowly lower the upper section of the sling while the hand chain hoist is operated to pull the upper section of the sling upward. Once the upper section of the sling is vertical and stable, the connection between the tower crane and the upper section of the sling is released, so that the upper section of the sling is vertically suspended above the catwalk. Furthermore, in step S100, after the zenith trolley is pulled to the preset area at the top of the main tower, the zenith trolley is fixedly connected to the catwalk load-bearing beam by a limiting device. The limiting device includes a hand-operated hoist and a steel wire rope. The two ends of the hand-operated hoist are fixedly connected to the zenith trolley and the catwalk load-bearing beam by steel wire ropes, respectively, thereby limiting the risk of the zenith trolley tilting or overturning during the upper sling hoisting operation and ensuring the stability and safety of the hoisting operation.

[0025] S200: Start the traction winch at the top of the main tower. Through the winch's uniform rope release action, drive the zenith trolley to move along the main cable direction with the upper section of the sling until the upper section of the sling is transported to the pre-designed installation position. Furthermore, in step S200, when the zenith trolley slides to a section of the main cable with a gentle slope and cannot slide autonomously due to insufficient gravity, it is manually pulled to move towards the mid-span of the main cable until the upper sling is precisely delivered to the corresponding clamp installation position. By connecting one end of the rope to the zenith trolley, the zenith trolley is pulled forward manually. During manual pulling, the pulling force is kept collinear with the sliding direction of the zenith trolley, and the spatial attitude of the upper sling is observed simultaneously to avoid the sling scraping against the catwalk or the main cable, ensuring that the upper sling is always suspended above the pre-set safe area above the catwalk, thus guaranteeing the stability and safety of the transportation process.

[0026] S300: The construction workers connect the guide rope to the lower end anchor head of the upper section of the sling. By manually pulling the guide rope, the lower end of the upper section of the sling is pulled around the groove of the cable clamp. At the same time, the hand-operated hoist is lowered so that the upper section of the sling hangs down naturally under its own weight. The spatial posture of the sling is adjusted until the central axis of the upper section of the sling coincides with the zenith line of the cable clamp. Furthermore, during the manufacturing stage, a marker point A is marked at the preset center position of the upper section sling. After the upper section sling is transported to the construction site, marker points B and C are marked on both sides of the reference marker point A, and the marker points B and C are symmetrically arranged relative to the reference marker point A.

[0027] Furthermore, step S300 specifically includes the following steps: S310: After the zenith trolley is transported to the preset installation position with the upper section of the sling, the zenith trolley is fixedly connected to the catwalk load-bearing beam by the limiting device to restrict the displacement and overturning tendency of the zenith trolley. S320: The construction workers connect the guide rope to the lower anchor head of the upper sling. By manually pulling the guide rope, the lower end of the upper sling is pulled around the groove of the cable clamp. At the same time, the hand-operated hoist is lowered so that the upper sling hangs down naturally under its own weight. After the mark point A of the upper sling is aligned with the zenith line of the cable clamp, the upper sling and the cable clamp are temporarily anchored with slings to prevent the sling from shifting. S330: Transfer the fixing device to the installation position. The fixing device includes a sling clamp, anchor bolts, and a sling liner. First, assemble the sling liner at the symmetrical marking points B and C of the upper sling. Then, clamp the sling clamp at the location of the sling liner to secure the upper sling and prevent axial slippage. Next, fasten the anchor head at one end of the upper sling to the connecting plate at the other end of the anchor head. Finally, release the temporary anchoring measures. S340: Observe the overlap between the mark point A of the upper sling and the zenith line of the cable clamp. If there is a deviation, use a hand-operated hoist to fine-tune the spatial posture of the upper sling until the mark point A and the zenith line of the cable clamp are completely overlapped. Then fix the sling clamp with anchor bolts. S350: If the mark point A of the upper sling shifts to the left, then assemble the hand chain hoist on the right side of the sling clamp and connect it to the upper sling through a soft sling. Operate the hand chain hoist to pull and adjust the sling. If the mark point A of the upper sling shifts to the right, then assemble the hand chain hoist on the left side of the sling clamp and connect it to the upper sling through a soft sling. Operate the hand chain hoist to pull and adjust the sling until the mark point A precisely coincides with the zenith line of the sling clamp.

[0028] Furthermore, the inner lining of the sling is made of rubber, and its shape is adapted to the outer wall of the sling, so as to achieve a tight fit with the sling body.

[0029] Specifically, by using marker point A as the positioning reference instead of the traditional estimation method, the alignment accuracy of the slings and clamps is significantly improved. This lays a solid foundation for precise docking of the upper and lower slings and uniform overall stress distribution. For left and right misalignment, a directional adjustment scheme using hand-operated hoists on opposite sides of the clamps is adopted to precisely balance the misalignment force, reduce the number of trials and errors, shorten the high-altitude operation time, and reduce safety risks. At the same time, after precise alignment, the clamps are tightened to fix the slings, which can avoid uneven contact stress caused by sling misalignment. This prevents the slings from slipping in the clamp grooves and becoming tight at one end and loose at the other during the subsequent stiffening beam hoisting load transfer, and prevents local stress concentration and friction damage to the slings.

[0030] By fixing both ends of the upper sling with a fixing device, an axial limiting constraint is formed on the upper sling. During the stiffening beam hoisting and lowering stress construction stage, the self-weight load of the stiffening beam is transferred to the upper sling through the lower sling. This effectively prevents the upper sling from axially slipping in the cable clamp groove due to the imbalance of forces at both ends. It also eliminates the uneven force phenomenon of one end being taut and the other end being slack in the upper sling, ensuring that the stress state and spatial posture of the upper sling always meet the design requirements. At the same time, it avoids friction damage caused by slippage between the cable clamp groove and the sling, improving the structural stability and service safety of the sling installation.

[0031] S400: Repeat steps S100 to S300 to complete the installation of all upper section suspenders for the entire bridge in sequence. During the installation of each upper section suspender, the principle of symmetrical construction from the main tower to the mid-span is followed. The alignment accuracy and fixing quality of each upper section suspender are controlled simultaneously. After the installation of a single upper section suspender is completed, the coincidence of the mark point A with the zenith line of the cable clamp and the anchoring torque of the suspender clamp are checked immediately to ensure that the installation accuracy and stress state of the upper section suspenders of the entire bridge meet the unified design standards. This lays the foundation for the accurate connection of the subsequent lower section suspenders and the overall stress stability of the entire bridge suspender system.

[0032] S500: The catwalk is re-suspended on the main cable, and the upper end of the lower sling is fastened to the connecting plate at the bottom of the upper sling according to the preset construction sequence. By relocating the catwalk to the main cable, the catwalk's load-bearing system is transformed from an anchorage system to the main cable, allowing the catwalk's alignment to adapt synchronously with subsequent deformations of the main cable.

[0033] Furthermore, in step S500, when the length of the lower sling is less than or equal to 10m, the following steps are specifically included: A tower crane is used to hoist the lower section of the sling to the working plane of the catwalk. Two zenith trolleys are installed on the gantry load-bearing cable. Two traction winches are installed at the top of the main tower. The traction winches are connected to the two zenith trolleys one by one by steel wire rope. The bottom of each zenith trolley is equipped with a hand chain hoist. The zenith trolley is pulled to the vicinity of the main tower by the traction winches. Then, the two zenith trolleys are fixedly connected to the catwalk load-bearing crossbeam by the limiting device. First, connect the hand-operated hoist on the trolley at the front end to the lower anchor head of the lower sling. Drive the lower end of the lower sling upwards through the hand-operated hoist, and simultaneously control the tower crane to lower the other end of the lower sling to the preset position. Then connect the hand-operated hoist on the trolley at the rear end to that end of the lower sling. After completing the connection, disconnect the steel wire rope of the tower crane from the lower sling. Start the two traction winches at the top of the main tower, and drive the two zenith trolleys to move the lower section of the sling along the gantry load-bearing cable at a uniform speed to deliver the lower section of the sling to the designed installation position. Set up a steering wheel on the catwalk directly below the cable clamp, adjust the hand chain hoist on the front zenith trolley, drive the lower section of the sling to descend and pass it through the steering wheel, disconnect the front hand chain hoist from the lower section of the sling, and slowly move the rear zenith trolley towards the cable clamp so that the lower section of the sling is oriented and lowered smoothly along the steering wheel; After the rear zenith trolley moves to a position directly above the cable clamp, the lower section of the sling is slowly lowered using a hand-operated hoist on the rear zenith trolley. When the upper end of the lower section of the sling is close to the catwalk surface, a hand-operated hoist is temporarily installed on the cable clamp. The hand-operated hoist is connected to the upper anchor head of the lower section of the sling via a soft sling. The connection between the lower section of the sling and the hand-operated hoist on the rear zenith trolley is then released. The hand-operated hoist on the cable clamp is then manipulated to slowly lower the lower section of the sling to the height required to align the mounting hole of the upper anchor head with the mounting hole of the bottom connecting plate of the upper section of the sling. The lower section of the sling is then securely connected to the connecting plate using a pin.

[0034] Furthermore, after the two zenith trolleys are towed to the preset area at the top of the main tower, the two zenith trolleys are fixedly connected to the catwalk load-bearing beams by limiting devices. After the two zenith trolleys, carrying the upper section of the sling, are transported to the preset installation position, the zenith trolleys are fixedly connected to the catwalk load-bearing beam using a limiting device.

[0035] By employing a one-to-one configuration of dual zenith trolleys and dual traction winches, coupled with fixed limiting devices, synchronous and stable movement of the slings is ensured during transportation, preventing sling deviation and twisting, thus adapting to the high-altitude catwalk operation environment. The placement of the steering wheels enables precise control of the sling lowering direction, and combined with the tiered operation of the front and rear hand-operated hoists, it replaces the traditional single-lifting mode, significantly improving the stability of sling lowering and preventing damage from slings to the catwalk or sling clamps. The hand-operated hoists for the sling clamps complete the force transfer and height fine-tuning, achieving precise alignment between the sling anchor head and the connecting plate mounting holes, ensuring the coaxiality and tightness of the connection nodes. The entire process is completed using conventional tools, with standardized and controllable operation procedures, requiring no complex equipment, balancing construction efficiency and safety, effectively shortening high-altitude operation time, and providing a guarantee for reliable connection of upper and lower sling sections and subsequent stiffening beam lifting and load transfer.

[0036] Furthermore, in step S500, when the length of the lower sling is greater than 10m, the following steps are specifically included: The lower section of the sling is transported to the location directly below the preset installation position. A steering wheel is then installed directly below the sling clamp corresponding to the installation position. The wire rope of the main tower top traction winch is wound around the steering wheel and lowered to the location of the lower section of the sling. The wire rope is connected to the end of the lower section of the sling through a soft sling. The traction winch is started and the wire rope is wound up at a uniform speed. The lower section of the sling is gradually pulled upward in the vertical direction by the traction force of the wire rope. When the upper anchor head of the lower sling is about to approach the connecting plate at the bottom of the upper sling, install a hand-operated hoist on the cable clamp, connect the hand-operated hoist to the upper anchor head of the lower sling, disconnect the lower sling from the steel wire rope of the tower top traction winch, and realize the transfer of the force system of the lower sling from the winch steel wire rope to the hand-operated hoist on the cable clamp. Adjust the spatial position and posture of the upper anchor head of the lower sling by using the hand-operated hoist on the cable clamp, so that the pin hole of the upper anchor head of the lower sling is coaxially aligned with the pin hole of the bottom connecting plate of the upper sling. Insert the pin into the aligned pin hole to complete the fastening connection between the lower and upper slings.

[0037] The directional placement of the steering wheels constrains the traction direction of the wire rope, ensuring a smooth, vertical lift of the sling. This prevents damage from friction between the sling and the catwalk or cable clamps, preserving the sling's integrity. A winch retracts the sling at a uniform speed, achieving steady lifting and replacing manual handling. This significantly reduces the intensity and safety risks of high-altitude work, improves lifting efficiency, and precisely transitions the force system. The sling smoothly transitions from winch traction to cable clamp control via a hand-operated hoist, facilitating subsequent fine-tuning and solving the problem of difficult sling alignment at heights. The hand-operated hoist allows for precise adjustment of the sling's spatial posture, ensuring coaxial alignment between the anchor pin hole and the connecting plate pin hole, guaranteeing the structural strength and coaxiality of the connection node and ensuring uniform force distribution across the upper and lower sling sections. The entire process is standardized, easy to operate, requires no complex equipment, and balances construction safety and reliability.

[0038] Furthermore, when installing the lower section of the suspenders at the cable clamps in the vicinity of the main tower, the lower section of the suspenders is placed on the top surface of the steel box girder or the top surface of the steel platform. For the lower section of the suspenders to be installed in other areas, transport vessels are used to transport them to the water position directly below the corresponding cable clamp.

[0039] Furthermore, before the installation of the lower section of the sling, according to the construction process requirements, a hoisting through hole is opened at the corresponding position of the catwalk mesh directly below the sling clamp. After the installation of the lower section of the sling is completed, the hoisting through hole is protected by a guardrail or by a safety net. The upper end of the safety net is fixedly connected to the sling clamp, and the lower end is securely connected to the catwalk mesh. Specifically, at the sling clamp corresponding to a regular sling, the opening size of the hoisting through hole is 1.10m in the longitudinal direction of the bridge and 0.40m in the transverse direction of the bridge; at the sling clamp corresponding to a reinforced sling, the opening size of the hoisting through hole is 1.80m in the longitudinal direction of the bridge and 0.4m in the transverse direction of the bridge.

[0040] After the main cable alignment adjustment is completed (i.e., after the main cable bracing operation is completed), the construction personnel use special pliers to cut the fine and coarse mesh of the catwalk according to the preset opening size. After cutting, the hoisting through holes are temporarily covered and protected with wire mesh or safety net to prevent the risk of falling objects and personnel from height.

[0041] After the installation of the lower section of slings is completed, permanent protective measures shall be taken for the hoisting through hole: guardrails may be used for enclosure and protection, or safety nets may be used for full enclosure. The upper end of the safety net shall be securely connected to the sling clamps, and the lower end shall be rigidly fixed to the catwalk surface net to ensure the stability and sealing of the protective structure and meet the safety protection standards for high-altitude operations.

[0042] S600: The stiffening girder is hoisted to a preset position higher than the design elevation. The lower end anchor of the lower section of the suspender cable is anchored to the lifting lug on the stiffening girder. The hoisting equipment is operated to drive the stiffening girder to slowly lower it, so that the suspender cable gradually bears the load of the stiffening girder, completing the force system conversion of the suspender cable. The fixing device used to fix the upper section of the suspender cable is removed. During the removal process, care is taken to avoid scratching or damaging the upper section of the suspender cable and cable clamps, ensuring that the entire bridge suspender cable system can be stably used under the preset working conditions, laying the foundation for the subsequent bridge deck construction.

[0043] Those skilled in the art will readily understand that the above description is merely 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 scope of protection of the present invention.

Claims

1. A method for installing a straddle-type sling, characterized in that, Includes the following steps: S100: Using a traction winch located at the top of the main tower, the zenith trolley is pulled to a predetermined area at the top of the main tower. The upper section of the sling is lifted by a tower crane located near the main tower and positioned above the catwalk. The connecting plate connected to the lower anchor of the upper section of the sling is connected to the hand chain hoist on the zenith trolley. The tower crane is operated to slowly lower the upper section of the sling while the hand chain hoist is operated to pull the upper section of the sling upward. Once the upper section of the sling is vertical and stable, the connection between the tower crane and the upper section of the sling is released, so that the upper section of the sling is vertically suspended above the catwalk. S200: Start the traction winch at the top of the main tower. Through the winch's uniform rope release action, drive the zenith trolley to move along the main cable direction with the upper section of the sling until the upper section of the sling is transported to the pre-designed installation position. S300: The construction workers connect the guide rope to the lower end anchor head of the upper section of the sling. By manually pulling the guide rope, the lower end of the upper section of the sling is pulled around the groove of the cable clamp. At the same time, the hand-operated hoist is lowered so that the upper section of the sling hangs down naturally under its own weight. The spatial posture of the sling is adjusted until the central axis of the upper section of the sling coincides with the zenith line of the cable clamp. S400: Repeat steps S100 to S300 to complete the installation of all upper section slings of the entire bridge in sequence; S500: The catwalk is re-suspended on the main cable, and the upper end of the lower sling is fastened to the connecting plate at the bottom of the upper sling according to the preset construction sequence. S600: The stiffening beam is hoisted to a preset position higher than the design elevation. The lower end anchor of the lower sling is anchored to the lifting lug on the stiffening beam. The hoisting equipment is controlled to drive the stiffening beam to slowly lower, so that the sling gradually bears the load of the stiffening beam, and the force system of the sling is transformed.

2. The straddle-type sling installation method according to claim 1, characterized in that, In step S100, after the zenith trolley is pulled to the preset area at the top of the main tower, the zenith trolley is fixedly connected to the catwalk load-bearing beam by a limiting device. The limiting device includes a hand-operated hoist and a wire rope. The two ends of the hand-operated hoist are fixedly connected to the zenith trolley and the catwalk load-bearing beam by wire ropes, respectively, thereby limiting the risk of the zenith trolley tilting or overturning during the upper sling hoisting operation and ensuring the stability and safety of the hoisting operation.

3. The straddle-type sling installation method according to claim 1, characterized in that, In step S200, when the zenith trolley slides to a section of the main cable with a gentle slope and cannot slide autonomously due to insufficient gravity, the zenith trolley is driven to move towards the middle of the main cable span by manual traction until the upper section of the suspender is accurately delivered to the corresponding cable clamp installation position.

4. The method for installing a straddle-type sling according to claim 1, characterized in that, During the manufacturing stage, a marker point A is marked at the preset center position of the upper section of the sling. After the upper section of the sling is transported to the construction site, marker points B and C are marked on both sides of the reference marker point A, and the marker points B and C are symmetrically arranged with respect to the reference marker point A.

5. The method for installing a straddle-type sling according to claim 1, characterized in that, Step S300 specifically includes the following steps: S310: After the zenith trolley is transported to the preset installation position with the upper section of the sling, the zenith trolley is fixedly connected to the catwalk load-bearing beam by the limiting device to restrict the displacement and overturning tendency of the zenith trolley. S320: The construction workers connect the guide rope to the lower anchor head of the upper sling. By manually pulling the guide rope, the lower end of the upper sling is pulled around the groove of the cable clamp. At the same time, the hand-operated hoist is lowered so that the upper sling hangs down naturally under its own weight. After the mark point A of the upper sling is aligned with the zenith line of the cable clamp, the upper sling and the cable clamp are temporarily anchored with slings to prevent the sling from shifting. S330: Transfer the fixing device to the installation position. The fixing device includes a sling clamp, anchor bolts, and a sling liner. First, assemble the sling liner at the symmetrical marking points B and C of the upper sling. Then, clamp the sling clamp at the location of the sling liner to secure the upper sling and prevent axial slippage. Next, fasten the anchor head at one end of the upper sling to the connecting plate at the other end of the anchor head. Finally, release the temporary anchoring measures. S340: Observe the overlap between the mark point A of the upper sling and the zenith line of the cable clamp. If there is a deviation, use a hand-operated hoist to fine-tune the spatial posture of the upper sling until the mark point A and the zenith line of the cable clamp are completely overlapped. Then fix the sling clamp with anchor bolts. S350: If the mark point A of the upper sling shifts to the left, then assemble the hand chain hoist on the right side of the sling clamp and connect it to the upper sling through a soft sling. Operate the hand chain hoist to pull and adjust the sling. If the mark point A of the upper sling shifts to the right, then assemble the hand chain hoist on the left side of the sling clamp and connect it to the upper sling through a soft sling. Operate the hand chain hoist to pull and adjust the sling until the mark point A precisely coincides with the zenith line of the sling clamp.

6. The method for installing a straddle-type sling according to claim 1, characterized in that, In step S500, when the length of the lower sling is less than or equal to 10m, the specific steps include: A tower crane is used to hoist the lower section of the sling to the working plane of the catwalk. Two zenith trolleys are installed on the gantry load-bearing cable. Two traction winches are installed at the top of the main tower. The traction winches are connected to the two zenith trolleys one by one by steel wire rope. The bottom of each zenith trolley is equipped with a hand chain hoist. The zenith trolley is pulled to the vicinity of the main tower by the traction winches. Then, the two zenith trolleys are fixedly connected to the catwalk load-bearing crossbeam by the limiting device. First, connect the hand-operated hoist on the trolley at the front end to the lower anchor head of the lower sling. Drive the lower end of the lower sling upwards through the hand-operated hoist, and simultaneously control the tower crane to lower the other end of the lower sling to the preset position. Then connect the hand-operated hoist on the trolley at the rear end to that end of the lower sling. After completing the connection, disconnect the steel wire rope of the tower crane from the lower sling. Start the two traction winches at the top of the main tower, and drive the two zenith trolleys to move the lower section of the sling along the gantry load-bearing cable at a uniform speed to deliver the lower section of the sling to the designed installation position. Set up a steering wheel on the catwalk directly below the cable clamp, adjust the hand chain hoist on the front zenith trolley, drive the lower section of the sling to descend and pass it through the steering wheel, disconnect the front hand chain hoist from the lower section of the sling, and slowly move the rear zenith trolley towards the cable clamp so that the lower section of the sling is oriented and lowered smoothly along the steering wheel; After the rear zenith trolley moves to a position directly above the cable clamp, the lower section of the sling is slowly lowered using a hand-operated hoist on the rear zenith trolley. When the upper end of the lower section of the sling is close to the catwalk surface, a hand-operated hoist is temporarily installed on the cable clamp. The hand-operated hoist is connected to the upper anchor head of the lower section of the sling via a soft sling. The connection between the lower section of the sling and the hand-operated hoist on the rear zenith trolley is then released. The hand-operated hoist on the cable clamp is then manipulated to slowly lower the lower section of the sling to the height required to align the mounting hole of the upper anchor head with the mounting hole of the bottom connecting plate of the upper section of the sling. The lower section of the sling is then securely connected to the connecting plate using a pin.

7. The straddle-type sling installation method according to claim 6, characterized in that, After the two zenith trolleys are towed to the preset area at the top of the main tower, the two zenith trolleys are fixedly connected to the catwalk load-bearing beams by the limiting device. After the two zenith trolleys, carrying the upper section of the sling, are transported to the preset installation position, the zenith trolleys are fixedly connected to the catwalk load-bearing beam using a limiting device.

8. The method for installing a straddle-type sling according to claim 1, characterized in that, In step S500, when the length of the lower sling is greater than 10m, the specific steps include: The lower section of the sling is transported to the location directly below the preset installation position. A steering wheel is then installed directly below the sling clamp corresponding to the installation position. The wire rope of the main tower top traction winch is wound around the steering wheel and lowered to the location of the lower section of the sling. The wire rope is connected to the end of the lower section of the sling through a soft sling. The traction winch is started and the wire rope is wound up at a uniform speed. The lower section of the sling is gradually pulled upward in the vertical direction by the traction force of the wire rope. When the upper anchor head of the lower sling is about to approach the connecting plate at the bottom of the upper sling, install a hand-operated hoist on the cable clamp, connect the hand-operated hoist to the upper anchor head of the lower sling, disconnect the lower sling from the steel wire rope of the tower top traction winch, and realize the transfer of the force system of the lower sling from the winch steel wire rope to the hand-operated hoist on the cable clamp. Adjust the spatial position and posture of the upper anchor head of the lower sling by using the hand-operated hoist on the cable clamp, so that the pin hole of the upper anchor head of the lower sling is coaxially aligned with the pin hole of the bottom connecting plate of the upper sling. Insert the pin into the aligned pin hole to complete the fastening connection between the lower and upper slings.

9. A method for installing a straddle-type sling according to claim 8, characterized in that, When installing the lower section of the suspender at the cable clamp in the vicinity of the main tower, the lower section of the suspender is placed on the top surface of the steel box girder or the top surface of the steel platform. For the lower section of the suspender to be installed in other areas, it is transported by transport vessel to the water position directly below the corresponding cable clamp.

10. The method for installing a straddle-type sling according to claim 1, characterized in that, Before the installation of the lower section of the sling, according to the construction process requirements, a hoisting through hole is opened at the corresponding position of the catwalk mesh directly below the sling clamp. After the installation of the lower section of the sling is completed, the hoisting through hole is protected by a guardrail or by a safety net. The upper end of the safety net is fixedly connected to the sling clamp, and the lower end is fastened to the catwalk mesh.

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