Device and method for reducing unbalanced horizontal force in process of tower beam lifting in multi-tower suspension bridge

Abstract

The application discloses a device and method for reducing unbalanced horizontal force in the process of hoisting girder of a multi-tower suspension bridge, and takes the middle tower as a balance boundary point, sets a traction adjusting steel strand on the other side of the hoisted first girder, and connects one end of the adjusting steel strand with the main cable on the small mileage side bearing the weight of the hoisted first girder through a temporary lock clamp, and connects the other end of the adjusting steel strand with the anchoring device on the side tower of the large mileage side, the adjusting steel strand is in the horizontal direction, and the adjusting steel strand is pulled by a tensioning device in the direction away from the small mileage side, so as to balance the horizontal force generated by the main cable on the small mileage side at the saddle when the first girder is hoisted, and indirectly suppresses the relative sliding between the cable strand and the saddle groove, the operation is convenient and rapid, the adjusting performance is strong, the device is suitable for the construction of the multi-tower suspension bridge with large girder-cable weight ratio, effectively improves the safety and structural integrity in the construction process, and greatly improves the quality and efficiency of the construction of the bridge type.

Description

Technical Field

[0001] This invention relates to the field of construction technology for multi-tower suspension bridges. More specifically, this invention relates to a device and method for reducing unbalanced horizontal forces during the lifting of beams from towers in a multi-tower suspension bridge. Background Technology

[0002] The beam-to-cable weight ratio of a suspension bridge refers to the ratio of the weight of a standard beam segment to the weight of a single-span main cable. An excessively high beam-to-cable weight ratio means that the stiffening girder has a relatively large self-weight. Therefore, during the lifting process, the increase in cable force on the main cable due to the lifting of a single stiffening girder segment will be significant. This excessive increase in cable force will lead to an excessive unbalanced horizontal force at the cable saddle. An excessively large unbalanced horizontal force will reduce the anti-slip safety factor of the main cable saddle and may even cause relative slippage between the main cable and the saddle, creating a safety hazard. This problem is most likely to occur during the lifting of the first beam segment. Previously constructed multi-tower suspension bridges have had cable weight ratios within a reasonable range, so no temporary measures were taken during construction to adjust the unbalanced horizontal force at the central tower. However, for multi-tower suspension bridges with a large beam-to-cable weight ratio, if no measures are taken during construction, the safety of the construction process cannot be guaranteed.

[0003] Current research on cable saddle anti-slip mainly focuses on increasing the nominal friction coefficient between the cable strands and the saddle groove to enhance the anti-slip force between them. Specific measures include installing friction plates within the saddle groove to increase the contact area between the cable strands and the saddle, thereby raising the limit of sliding friction. However, this measure has limited effectiveness in improving anti-slip force, and the friction plates are prone to fatigue damage. Another study proposes making the middle tower of a three-tower suspension bridge a flexible tower to reduce the unbalanced force on the main cables on both sides. However, an excessively flexible middle tower inevitably leads to an excessively large deflection-to-span ratio under live load, compromising train stability and safety.

[0004] Furthermore, existing anti-skid measures are mainly aimed at the completed bridge stage, but in fact, the anti-skid problem of cable saddles also needs to be considered during the construction process, especially during the hoisting stage of the first beam segment. At present, there is no mature and feasible solution system for the hoisting stage of the first beam segment. Summary of the Invention

[0005] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0006] Another objective of this invention is to provide a device and method for reducing unbalanced horizontal forces during the hoisting process of the middle tower of a multi-tower suspension bridge, in order to solve the technical problem of unbalanced forces on the left and right sides of the main cable connected at the middle tower when hoisting the first beam of a multi-tower suspension bridge.

[0007] To achieve these objectives and other advantages according to the invention, in one aspect, the invention provides a device for reducing unbalanced horizontal forces during the lifting of the middle tower of a multi-tower suspension bridge. The device includes adjusting steel strands for adjusting the horizontal tension of the main cable. The main cable is divided into a low-mileage side and a high-mileage side on both sides of the middle tower according to the distance between the middle tower and the side towers. An anchoring device is provided on the upper end of the side tower on the high-mileage side, facing the middle tower. The adjusting steel strands are arranged horizontally, with one end connected to the anchoring device via a tensioning device and the other end connected to the main cable on the low-mileage side via a temporary locking clamp. The tensioning device is used to stretch the adjusting steel strands towards the side tower.

[0008] Preferably, the anchoring device includes a limiting steel plate that is fitted to the side of the side tower column facing the central tower. The side of the limiting steel plate facing the side tower has an embedded part, and the side tower has an anchoring steel bar. The limiting steel plate is fixedly connected to the anchoring steel bar through the embedded part, and the side of the limiting steel plate facing the central tower is connected to the tensioning device.

[0009] On the other hand, the present invention also provides a method for reducing unbalanced horizontal forces during the tower crane beam process in a multi-tower suspension bridge, comprising the following construction steps: After the construction of S1, the tower, anchorage, saddle, main cable structure, and cable crane system, the small mileage side and large mileage side of the main cable relative to the middle tower are determined. The anchoring device is installed on the upper end of the side tower on the large mileage side. The temporary locking clamp is installed at the end of the main cable on the small mileage side near the middle tower. The temporary locking clamp and the anchoring device are at the same height. Then, the adjusting steel strand and the tensioning device are installed between the temporary locking clamp and the anchoring device. S2. Before lifting the beam, observe whether the main cable slips relative to the saddle groove and ensure that the main cable is installed in a balanced manner; S3. Pre-tension the adjustment steel strands to balance the unbalanced horizontal force generated by the main cable when hoisting the first beam segment; S4. Hoist the first beam segment on the low mileage side and observe in real time whether the main cable slips relative to the middle tower saddle. If misalignment occurs, stop the beam hoisting operation in time and resolve the misalignment problem. S5. When hoisting the first beam segment on the high-mileage side, observe in real time whether the main cable is sliding relative to the saddle of the middle tower. If misalignment occurs, stop the beam hoisting operation in time and resolve the misalignment problem. S6. After the first two beam segments on the low mileage side and the high mileage side are hoisted, remove the temporary locking clamp, the adjusting steel strand, the tensioning device, and the anchoring device, and then continue the hoisting work of the subsequent beam segments.

[0010] Preferably, when observing whether the main cable is sliding relative to the central tower saddle, under the balanced state of the main cable, a center displacement observation line L1 is drawn at the center position of the central tower saddle seat, and a displacement observation line L2 is drawn at the corresponding positions of the main cable on both sides of the central tower saddle seat. During the beam hoisting process, the relative horizontal displacement of L1 and L2 is observed in real time to determine whether misalignment has occurred.

[0011] Preferably, in step S3, when pre-tensioning the regulating steel strand, the pre-tensioning horizontal force F is applied based on the increase in the tension of the main cable on the low mileage side, which leads to the increase in the unbalanced horizontal force generated at the top of the middle tower. F is calculated by the following formula: In the formula, P is the weight of the hoisted beam segment, and C is the hoisting span-to-rise ratio. Let L be the magnitude of the uniformly distributed load of the main cable 1's self-weight, and L be the span of the span where the suspension beam is located. The beam-to-cable weight ratio, The pretension coefficient is taken as 0.5, and F0 is the horizontal force of the main cable in the span where the first beam segment is located under the uniformly distributed load ω of its own weight before the first beam segment is hoisted.

[0012] The present invention includes at least the following beneficial effects: The device and method for reducing the unbalanced horizontal force during the lifting of the first beam in a multi-tower suspension bridge uses the middle tower as the balance dividing point. On the other side of the first beam being lifted, an adjustment steel strand is traction-set. One end of the adjustment steel strand is connected to the main cable on the lower mileage side, which bears the weight of the first beam being lifted, through a temporary locking clamp, serving as the force-applying traction end. The other end of the adjustment steel strand is connected to the anchoring device on the side tower on the higher mileage side. The adjustment steel strand is in a horizontal direction. By using a tensioning device, the adjustment steel strand is pulled away from the lower mileage side to balance the horizontal force generated at the cable saddle on the main cable on the lower mileage side when lifting the first beam. This reduces the magnitude of the unbalanced horizontal force on both sides of the middle tower after the beam is lifted, indirectly suppressing the relative slippage between the cable strand and the saddle groove. The operation is convenient and quick, with strong adjustability. It is suitable for the construction of multi-tower suspension bridges with a large beam-to-cable weight ratio, effectively improving the safety and structural integrity during construction, and greatly enhancing the quality and efficiency of this type of bridge construction.

[0013] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall layout of the present invention; Figure 2 This is an enlarged structural diagram of the temporary locking clip of the present invention; Figure 3 This is an enlarged structural diagram of the anchoring device of the present invention; Figure 4 This is a structural schematic diagram of steps S1-S3 of the method for reducing unbalanced horizontal forces during the tower crane beam process in a multi-tower suspension bridge according to the present invention. Figure 5 This is a schematic diagram of step S4 of the method for reducing unbalanced horizontal forces during the tower crane beam process in a multi-tower suspension bridge according to the present invention. Figure 6 This is a structural schematic diagram of step S5 corresponding to the method for reducing unbalanced horizontal forces during the process of tower crane beams in a multi-tower suspension bridge according to the present invention. Figure 7 This is a schematic diagram of step S6 of the method for reducing unbalanced horizontal forces during the tower crane beam process in a multi-tower suspension bridge according to the present invention. Figure 8 This is a schematic diagram of the arrangement of the present invention when observing whether the main cable slides relative to the middle tower saddle; The following are the reference numerals in the instruction manual: 1—Main cable, 2—Middle tower, 3—Middle tower main cable saddle, 4—First beam segment, 5—Temporary cable clamp, 6—Adjusting steel strand, 7—Anchoring device, 8—Anchoring reinforcement, 9—Embedded part, 10—Limiting steel plate, 11—Anchor beam, 12—Adjusting tie rod, 13—Jack, 14—Saddle, 15—Cable strand, 16—Displacement observation line L1, 17—Displacement observation line L2, 18—Side tower. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0016] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0017] like Figure 1 , Figure 5-7As shown, the present invention provides a device for reducing the unbalanced horizontal force during the lifting of the middle tower of a multi-tower suspension bridge. The device includes a steel strand 6 for adjusting the horizontal tension of the main cable 1. The main cable 1 is divided into a low-mileage side and a high-mileage side on both sides of the middle tower 2 according to the distance between the middle tower 2 and the side tower 18. An anchoring device 7 is provided on the upper end of the side tower 18 on the high-mileage side facing the middle tower 2. The steel strand 6 is arranged horizontally, and one end is connected to the anchoring device 7 through a tensioning device, and the other end is connected to the main cable 1 on the low-mileage side through a temporary locking clamp 5. The tensioning device is used to stretch the steel strand 6 towards the side tower 18.

[0018] When hoisting the first girder of a multi-tower suspension bridge, the middle tower 2 is used as the balance dividing point. On the other side of the hoisted first girder, a regulating steel strand 6 is installed. One end of the regulating steel strand 6 is connected to the main cable 1 on the lower mileage side, which bears the weight of the hoisted first girder, through a temporary locking clamp 5, serving as the force-applying traction end. The other end of the regulating steel strand 6 is connected to the anchoring device 7 on the side tower 18 on the higher mileage side. A set of regulating steel strands 6 is installed on each side of the main cable 1, and the regulating steel strands 6 are in a horizontal direction. By pulling the tensioning device in a direction away from the small mileage side, the steel strand 6 is adjusted to balance the horizontal force generated at the cable saddle 3 of the main cable 1 on the small mileage side when hoisting the first beam. This reduces the magnitude of the unbalanced horizontal force on both sides of the middle tower 2 after the beam is hoisted, and indirectly suppresses the relative slippage between the cable strand 15 and the saddle groove. The operation is convenient and quick, with strong adjustability. It is suitable for the construction of multi-tower suspension bridges with a large beam-to-cable weight ratio, effectively improving the safety and structural integrity during the construction process, and greatly enhancing the quality and efficiency of this type of bridge construction.

[0019] Tensioning devices are common in this technical field and are often used to connect with steel strands. By setting up a base and a reaction seat, and connecting the base and the reaction seat with a jack 13, the jack 13 is activated, the reaction seat provides the reaction force, and drives the steel strand connected to the base to be tensioned. There are many different structural forms, as long as the tensioning function is realized, it will not be described in detail here. When installing the adjustment steel strand 6, a winch is used for traction, and the installation is carried out in a manner similar to the erection of the main cable 1 strand 15.

[0020] In another technical solution, such as Figure 1 , 3As shown, the anchoring device 7 includes a limiting steel plate 10 that is fitted to the side of the side tower 18 facing the middle tower 2. The side of the limiting steel plate 10 facing the side tower 18 is provided with an embedded part 9. An anchoring steel bar 8 is provided on the side tower 18. The limiting steel plate 10 is fixedly connected to the anchoring steel bar 8 through the embedded part 9. The side of the limiting steel plate 10 facing the middle tower 2 is connected to the tensioning device. The adjusting steel strand 6 uses the side tower 18 on the side with the larger mileage (the side opposite to the first beam being hoisted) as the anchoring connection end, and the end closer to the middle tower 2 as the adjustment end, so as to keep the overall structure of the adjusting steel strand 6 under stress balance and stability during tensioning.

[0021] This embodiment also provides a structure for a tensioning device, including, for example... Figure 3 The two anchor beams 11 shown have an adjusting rod 12 at each end between them. One end of the rod is fixed to one of the anchor beams 11, and the other end is connected to a jack 13. The adjusting rod 12 is stretched by the jack 13. The adjusting steel strand 6 passes through the anchor beam 11 away from the limiting steel plate 10 and is then connected to the tensioning jack 13.

[0022] This invention also provides a method for reducing the unbalanced horizontal force on bridge towers during the girder lifting process of a multi-tower suspension bridge, combined with... Figure 4-8 As shown, the construction steps include the following: S1, such as Figure 4 As shown, after the construction of the tower, anchorage, saddle 3, main cable 1 structure, and cable crane system, the small mileage side and large mileage side of the main cable 1 relative to the middle tower 2 are determined. The anchoring device 7 is installed on the upper end of the side tower 18 on the large mileage side. The temporary locking clip 5 is installed at the end of the main cable 1 located on the small mileage side near the middle tower 2. The temporary locking clip 5 and the anchoring device 7 are located at the same height. Then, the adjusting steel strand 6 and the tensioning device are installed between the temporary locking clip 5 and the anchoring device 7.

[0023] The overall structural layout is as follows Figure 1 As shown, the smaller mileage is on the left and the larger mileage is on the right. First, the cable tower and anchorage are constructed. The main cable saddle 3 is installed to the preset position using the gantry crane on the top of the tower. Then, the catwalk is constructed. The main cable 1 is erected, tightened, and its alignment is adjusted using the catwalk. At the same time, the cable clamps and suspenders are installed. Finally, the cable crane system is installed to prepare for the hoisting of the stiffening beam. The process of erecting the steel strand 6 for adjustment is similar to that of erecting the main cable 1 strand 15. With the help of the catwalk and winch, the steel strand is installed to the designated position.

[0024] S2. Before hoisting the beam, observe whether the main cable 1 slips relative to the saddle groove and ensure that the main cable 1 is installed in a balanced manner. During the beam segment hoisting process, relative displacement between the saddle 3 and the main cable 1 is strictly prohibited.

[0025] S3. The adjusting steel strand 6 is pre-tensioned towards the right side of the high mileage using the tensioning device to pre-balance the unbalanced horizontal force generated by the main cable 1 when hoisting the first beam segment 4.

[0026] S4, such as Figure 5 As shown, the first beam segment 4 is hoisted on the lower mileage side. Real-time monitoring is conducted to check whether the main cable 1 slips relative to the saddle 3 of the central tower 2. If misalignment occurs, the hoisting operation is stopped immediately and the misalignment is resolved. Monitoring can be performed using sensors or displacement monitoring lines.

[0027] S5, such as Figure 6 As shown, when hoisting the first beam segment 4 on the high-mileage side, it is necessary to monitor in real time whether the main cable 1 is sliding relative to the saddle 3 of the middle tower 2. If misalignment occurs, the beam hoisting operation should be stopped immediately and the misalignment problem should be resolved.

[0028] S6, such as Figure 7 As shown, after the first two beam segments 4 on the low mileage side and the high mileage side are hoisted, the temporary locking clamp 5, the adjusting steel strand 6, the tensioning device, and the anchoring device 7 are removed, and then the hoisting work of the subsequent beam segments continues.

[0029] The method of reducing the unbalanced horizontal force of the bridge towers during the girder lifting process of a multi-tower suspension bridge can effectively solve the problem of slippage between the cable strand 15 and the saddle groove caused by the excessive unbalanced force on both sides of the middle tower 2 in the early stage of the girder lifting process of a multi-tower suspension bridge, greatly improving the construction efficiency and ensuring the safety of the construction process.

[0030] In another technical solution, such as Figure 8 As shown, when observing whether the main cable 1 slips relative to the saddle 3 of the middle tower 2, under the balanced state of the main cable 1, draw the center displacement observation line L1 16 at the center position of the saddle seat 14 of the middle tower saddle 3, and draw the displacement observation line L2 17 at the corresponding positions of the main cable 1 on both sides of the saddle seat 14 of the middle tower 2 saddle 3. During the beam hoisting process, observe the relative horizontal displacement of L1 16 and L2 17 in real time to determine whether misalignment has occurred.

[0031] After tensioning 6 steel strands for horizontal adjustment, the first beam on the lower mileage side is hoisted. Figure 5 As shown, the relative horizontal displacement changes of the displacement observation lines L1 16 and L2 17 at the saddle 3 of the middle tower should be observed in real time. If the two are misaligned, the beam lifting operation should be stopped in time and the cause of the displacement should be found.

[0032] After the first beam on the lower mileage side is hoisted, the first beam on the higher mileage side is then hoisted. Figure 6As shown, the relative horizontal displacement changes of the displacement observation lines L1 16 and L2 17 at the saddle 3 of the middle tower should be observed in real time. If the two are misaligned, the beam lifting operation should be stopped in time and the cause of the displacement should be found.

[0033] In another technical solution, such as Figure 4 As shown, in step S3, when pre-tensioning the regulating steel strand 6, the tension of the main cable 1 on the low mileage side increases, resulting in an increase in the unbalanced horizontal force at the top of the middle tower 2, which is applied accordingly. The horizontal force F for pretensioning is calculated using the following formula: In the formula, P is the weight of the hoisted beam segment, and C is the hoisting span-to-rise ratio. Let L be the magnitude of the uniformly distributed load of the main cable 1's self-weight, and L be the span of the span where the suspension beam is located. The beam-to-cable weight ratio, The pretension coefficient is taken as 0.5, and F0 is the horizontal force of the main cable in the span where the first beam segment is located under the uniformly distributed load ω of its own weight before the first beam segment is hoisted.

[0034] The above formula can be used to calculate the magnitude of the increase in horizontal force across the hoisting span after the first beam segment 4 is hoisted. The difference in horizontal force at the top of the middle tower 2 before the beam is hoisted is almost zero. Therefore, the increase in horizontal force across the hoisting span is the value of the unbalanced horizontal force at the top of the middle tower 2 after hoisting. The generation of unbalanced horizontal force reduces the anti-slip safety factor K. By pre-tensioning the horizontal steel strands before hoisting the first beam segment, the unbalanced horizontal force that occurs in real time during the beam hoisting process can be effectively balanced.

[0035] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A device for reducing unbalanced horizontal forces during the lifting of beams from towers in a multi-tower suspension bridge, characterized in that, It includes adjusting steel strands for adjusting the horizontal tension of the main cable. The main cable is divided into a small mileage side and a large mileage side on both sides of the middle tower according to the distance between the middle tower and the side tower. An anchoring device is installed on the upper end of the side tower on the large mileage side, facing the middle tower. The adjusting steel strands are set in the horizontal direction, and one end is connected to the anchoring device through a tensioning device, and the other end is connected to the main cable on the small mileage side through a temporary locking clamp. The tensioning device is used to stretch the adjusting steel strands toward the side tower.

2. The device for reducing unbalanced horizontal forces during the tower crane beam process in a multi-tower suspension bridge as described in claim 1, characterized in that, The anchoring device includes a limiting steel plate that is fitted to the side of the side tower column facing the middle tower. The side of the limiting steel plate facing the side tower has an embedded part, and the side tower has an anchoring steel bar. The limiting steel plate is fixedly connected to the anchoring steel bar through the embedded part, and the side of the limiting steel plate facing the middle tower is connected to the tensioning device.

3. The construction method of the device for reducing unbalanced horizontal forces during the tower crane beam process in a multi-tower suspension bridge as described in claim 1, characterized in that, The construction steps include the following: After the construction of S1, the tower, anchorage, saddle, main cable structure, and cable crane system, the small mileage side and large mileage side of the main cable relative to the middle tower are determined. The anchoring device is installed on the upper end of the side tower on the large mileage side. The temporary locking clamp is installed at the end of the main cable on the small mileage side near the middle tower. The temporary locking clamp and the anchoring device are at the same height. Then, the adjusting steel strand and the tensioning device are installed between the temporary locking clamp and the anchoring device. S2. Before lifting the beam, observe whether the main cable slips relative to the saddle groove and ensure that the main cable is installed in a balanced manner; S3. Pre-tension the adjustment steel strands to balance the unbalanced horizontal force generated by the main cable when hoisting the first beam segment; S4. Hoist the first beam segment on the low mileage side and observe in real time whether the main cable slips relative to the middle tower saddle. If misalignment occurs, stop the beam hoisting operation in time and resolve the misalignment problem. S5. When hoisting the first beam segment on the high-mileage side, observe in real time whether the main cable is sliding relative to the saddle of the middle tower. If misalignment occurs, stop the beam hoisting operation in time and resolve the misalignment problem. S6. After the first two beam segments on the low mileage side and the high mileage side are hoisted, remove the temporary locking clamp, the adjusting steel strand, the tensioning device, and the anchoring device, and then continue the hoisting work of the subsequent beam segments.

4. The construction method of the device for reducing unbalanced horizontal forces during the tower crane beam process in a multi-tower suspension bridge as described in claim 3, characterized in that, When observing whether the main cable is sliding relative to the central tower saddle, under the balanced state of the main cable, draw the center displacement observation line L1 at the center of the central tower saddle seat, and draw the displacement observation line L2 at the corresponding positions of the main cable on both sides of the central tower saddle seat. During the lifting process, observe the relative horizontal displacement of L1 and L2 in real time to determine whether misalignment has occurred.

5. The construction method of the device for reducing unbalanced horizontal forces during the tower crane beam process in a multi-tower suspension bridge as described in claim 3, characterized in that, In step S3, when pre-tensioning the regulating steel strand, a pre-tensioning horizontal force F is applied based on the increase in tension of the main cable on the low mileage side, which leads to the increase in the unbalanced horizontal force generated at the top of the middle tower. F is calculated by the following formula: In the formula, P is the weight of the hoisted beam segment, and C is the hoisting span-to-rise ratio. The magnitude of the uniformly distributed self-weight load of the main cable (1), where L is the span of the span where the suspension beam is located. The beam-to-cable weight ratio, The pretension coefficient is taken as 0.5, and F0 is the horizontal force of the main cable in the span where the first beam segment is located under the uniformly distributed load ω of its own weight before the first beam segment is hoisted.

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