Method for dealing with relaxation of cable steel strands during vertical rotation of arch ribs

Abstract

The present invention belongs to the technical field of bridge rotation construction, and specifically relates to a method for dealing with the relaxation of the cable strands of the stay cables during the vertical rotation of the arch rib, including the steps of pre-positioning the arch rib, lowering the arch rib vertically in rotation, continuously lowering the arch rib vertically in rotation, lifting the arch rib vertically in rotation, tensioning the cable strands of the stay cables that are loose at the front end of the cable tower, continuing to lift the arch rib vertically in rotation, and consolidating the vertical rotation system of the arch rib, which are set in sequence. The method of the present invention avoids the high-altitude operation of engineering personnel, improves the construction safety and enhances the construction efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge swing construction, and provides a method for dealing with the relaxation of the cable steel strands during the vertical rotation of the arch rib. Background Art

[0002] In terrain-complex areas, restricted by various factors, the bridge swing construction method is widely used. Affected by the topography and geomorphology at the bridge site, the arch rib may need to be rotated horizontally and vertically in combination multiple times to reach the designated position. Usually, the arch rib is vertically rotated to a higher angle than the designed position first and then rotated horizontally. After the horizontal rotation is in place, it is vertically rotated downward for the second time to facilitate crossing obstacles during the horizontal rotation process. As the vertical rotation angle of the arch rib increases, the axial tension of the cable gradually decreases. When the arch rib is vertically rotated to the high position, the cable steel strands at the front end of the cable tower will become slack and withdraw from the working state, resulting in a large stress borne by the remaining tensioned steel strands and a reduction in the structural safety factor. In this state, re-tensioning the slack steel strands requires tensioning each steel strand one by one at the cable connection point of the arch rib, with low construction efficiency and poor tensioning effect. In addition, since the arch rib is at a high position and has a large inclination angle at this time, it is difficult for personnel and equipment to reach the cable connection point of the arch rib for operation, and the construction risk is high. Summary of the Invention

[0003] In view of this, the purpose of the invention is to provide a method for dealing with the relaxation of the cable steel strands during the vertical rotation of the arch rib, which can avoid high-altitude operation of engineering personnel, improve construction safety and construction efficiency.

[0004] To achieve the above purpose, the invention provides the following technical solutions:

[0005] The invention provides a method for dealing with the relaxation of the cable steel strands during the vertical rotation of the arch rib, which is characterized by including the following steps:

[0006] ①, Pre-positioning the arch rib

[0007] During the vertical rotation of the arch rib, multiple bundles of cable steel strands are required, and the number of steel strands in a single bundle is relatively large. When each bundle of cable steel strands passes through the groove of the single-row pulley above the saddle, they will be arranged in layers, forming upper-layer cable steel strands, middle-layer cable steel strands and lower-layer cable steel strands; at the beginning of the vertical rotation of the arch rib, the bundled cable steel strands move along the arc formed by the surface of the pulley as the pulley rotates. At this time, the tensions P1 = P2 at both ends of the bundled cable steel strands. As the vertical rotation of the arch rib progresses, due to the difference in the moving track radius of each layer of cable steel strands, while each bundle of cable steel strands rotates with the pulley, the lower-layer cable steel strands will generate relative displacement and slide along the pulley groove, and each pulley generates a sliding friction force F on the lower-layer cable steel strands i , at this time, the tensions P1 = P2 + ∑F at both ends of the lower-layer cable steel strands i ; where ∑F i is the static friction force generated by the pulley on the lower-layer cable steel strands;

[0008] ②, The arch rib is vertically rotated and lowered.

[0009] As the vertical rotation angle of the arch rib increases, the axial tension of the cable strand of the tie cable gradually decreases. When the tension is less than the static friction force ∑F i i.e., P1 < ∑F i , at this time, the lower-layer cable strands of the tie cable at the front end of the tie tower will not produce relative displacement and slide along the pulley groove, and the lower-layer cable strands of the tie cable at the front end of the tie tower will become slack;

[0010] ③, The arch rib continues to be vertically rotated and lowered.

[0011] As the vertical rotation angle of the arch rib continues to increase, the slack of the lower-layer cable strands of the tie cable at the front end of the tie tower will gradually accumulate. At this time, the lowering of the arch rib is controlled by the vertical rotation jack, and the lowering distance of the cable strands of the bundled cable is generally 1 - 2 jack strokes; at this time, the cable strands of the tie cable at the saddle move along the arc formed by the pulley surface as the pulley rotates, the friction force is in the reverse direction and P2 < ∑F i , the lower-layer cable strands of the tie cable at the rear end of the tie tower will not produce relative displacement and slide along the pulley groove. Since the moving distance of the lower-layer cable strands of the tie cable is less than that of the upper-layer cable strands of the tie cable, the slack lower-layer cable strands of the bundled cable at the front end of the tie tower will be gradually tightened;

[0012] ④, The arch rib is vertically rotated and lifted to tighten the slack tie cable strands at the front end of the tie tower.

[0013] If the slack tie cable strands at the front end of the tie tower are not completely tightened after lowering 1 - 2 jack strokes, continue to vertically rotate and lift 1 - 2 jack strokes and then lower several times, and the slack tie cable strands at the front end of the tie tower can be tightened;

[0014] ⑤, The arch rib continues to be vertically rotated and lifted.

[0015] When the slack of the lower-layer cable strands of the tie cable at the front end of the tie tower gradually accumulates to a certain extent, perform the above steps ③ - ④ in sequence for the vertical rotation construction of the arch rib until the design position;

[0016] ⑥, Carry out the consolidation of the vertical rotation system of the arch rib.

[0017] Furthermore, in the above solution: Before the pre-positioning of the arch rib, the tie tower is fixed on the base of the vertical rotation device in advance, the saddle is fixed at the top of the tie tower, multiple pulleys are arranged on the saddle, the vertical rotation hinge is arranged on the base of the vertical rotation device, the arch rib with the bottom installed on the vertical rotation hinge, the top of the arch rib is connected to one end of the tie cable strand, and the other end of the tie cable strand passes through the pulley and is connected to the jack located on the base of the vertical rotation device.

[0018] The beneficial effects of the present invention are:

[0019] In the present invention, during the vertical rotation process of the arch rib, the slack cable strands of the fastening cables are lowered, lifted, and re-tensioned, avoiding high-altitude operations for engineering personnel, improving the construction efficiency, and enhancing the construction safety.

[0020] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. Brief Description of the Drawings

[0021] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0022] Figure 1 is a schematic structural diagram of the present invention;

[0023] Figure 2 is a distribution diagram of the fastening cable strands at the saddle;

[0024] Figure 3 is a schematic structural diagram of the distribution of the fastening cable strands inside the single-row pulley;

[0025] Figure 4 is a schematic structural diagram of the force on the lower-layer cable strands of the fastening cable;

[0026] Reference numerals: 1, arch rib; 2, pulley; 3, fastening cable strand; 4, fastening tower; 5, vertical rotation hinge; 6, saddle; 7, jack; 8, base of the vertical rotation device; 301, lower-layer cable strands of the fastening cable; 302, middle-layer cable strands of the fastening cable; 303, upper-layer cable strands of the fastening cable. Detailed Description of the Embodiments

[0027] The following illustrates the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention schematically. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0028] Among them, the attached drawings are only for illustrative purposes, showing only schematic diagrams rather than actual physical diagrams, and should not be construed as a limitation on this patent; in order to better illustrate the embodiments of the present invention, some components in the attached drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the attached drawings may be omitted. In addition, the present invention may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0029] As Figures 1-4 shown, a method for dealing with the relaxation of the cable - strand of the buckling cable during the vertical rotation of the arch rib of the present invention is characterized in that it includes the following steps.

[0030] ①, Pre - position the arch rib 1.

[0031] During the vertical rotation of the arch rib 1, multiple bundles of cable - strands of the buckling cable are required, and the number of cable - strands in a single bundle is relatively large. When each bundle of cable - strands 3 passes through the groove of the single - row pulley 2 above the cable saddle 6, they will be arranged in layers, forming the upper - layer cable - strands 303, the middle - layer cable - strands 302, and the lower - layer cable - strands 301; when the vertical rotation of the arch rib 1 starts, the bundled cable - strands 3 move along the arc formed by the surface of the pulley as the pulley rotates. At this time, the tensile forces P1 = P2 at both ends of the bundled cable - strands 3. As the vertical rotation of the arch rib 1 proceeds, due to the differences in the moving - track radii of each layer of cable - strands, while each bundle of cable - strands rotates with the pulley, the lower - layer cable - strands 301 will generate relative displacement and slide along the pulley groove, and each pulley generates a sliding friction force F i on the lower - layer cable - strands 301. At this time, the tensile forces at both ends of the lower - layer cable - strands 301 are P1 = P2+∑F i ; where ∑F i is the static friction force generated by the pulley on the lower - layer cable - strands 301.

[0032] ②, Lower the arch rib 1 during vertical rotation.

[0033] As the vertical - rotation angle of the arch rib 1 increases, the axial tensile force of the cable - strands 3 of the buckling cable gradually decreases. When the tensile force is less than the static friction force ∑F i , that is, P1<∑F i , at this time, the lower - layer cable - strands 301 of the buckling cable at the front end of the buckling tower 4 will not generate relative displacement and slide along the pulley groove, and the lower - layer cable - strands 301 of the buckling cable at the front end of the buckling tower 4 will show relaxation.

[0034] ③, Continuously lower the arch rib 1 during vertical rotation.

[0035] As the vertical rotation angle of the arch rib 1 continues to increase, the slack of the lower - layer steel strands 301 of the cable on the front end of the cable - tower 4 will gradually accumulate. At this time, the arch rib 1 is lowered by controlling the vertical - rotation jack 7. The lowering distance of the bundled - cable steel strand 3 is generally 1 - 2 strokes of the jack 7. At this time, the cable - strand of the cable on the saddle 6 moves reversely along the arc formed by the surface of the pulley as the pulley rotates, the frictional force is in the reverse direction and P2 < ∑F i , the lower - layer steel strands of the cable on the rear end of the cable - tower 4 will not produce relative displacement and slide along the pulley groove. Since the moving distance of the lower - layer steel strands of the cable is less than that of the upper - layer steel strands of the cable, the slack lower - layer steel strands of the bundled - cable 3 at the front end of the cable - tower 4 will be gradually tensioned;

[0036] ④, The arch rib is vertically rotated and lifted to tension the slack cable - strands of the cable on the front end of the cable - tower 4.

[0037] If the slack cable - strands of the cable on the front end of the cable - tower 4 are not completely tensioned after lowering 1 - 2 strokes of the jack 7, then continue to vertically rotate and lift 1 - 2 strokes of the jack 7 and lower several times again, then the slack cable - strands of the cable on the front end of the cable - tower 4 can be tensioned;

[0038] ⑤, The arch rib continues to be vertically rotated and lifted.

[0039] When the slack of the lower - layer steel strands 301 of the cable on the front end of the cable - tower 4 gradually accumulates to a certain extent, the above steps ③ - ④ are carried out in sequence for the vertical rotation construction of the arch rib until the design position;

[0040] ⑥, Carry out the consolidation of the vertical - rotation system of the arch rib. In this embodiment, during the entire process of the vertical rotation and lowering of the arch rib 1, the lower - layer steel strands 301 among the upper - layer cable - strands 303, middle - layer cable - strands 302, and lower - layer cable - strands 301 will become slack as the arch rib 1 is vertically rotated and lowered. The subsequent process of vertically rotating and lifting the arch rib is to tension the slack lower - layer steel strands 301. By lowering, lifting, and re - tensioning the slack lower - layer steel strands 301 during the vertical rotation process of the arch rib 1, it avoids high - altitude operations for engineering personnel, improves the construction efficiency, and enhances the construction safety.

[0041] To facilitate the rapid tensioning of the lower - layer steel strands 301 of the cable and improve the necessity of the preliminary preparation work, in the above - mentioned embodiment, preferably: before the pre - positioning of the arch rib 1, the cable - tower 4 is fixed on the vertical - rotation device base 8 in advance, the saddle 6 is fixed on the top of the cable - tower 4, there are multiple pulleys 2 arranged on the saddle 6, the vertical - rotation hinge 5 arranged on the vertical - rotation device base 8, the arch rib 1 with the bottom installed on the vertical - rotation hinge 5, the top of the arch rib 1 is connected to one end of the cable - strand 3 of the cable, and the other end of the cable - strand 3 passes through the pulley 2 and is connected to the jack 7 located on the vertical - rotation device base 8.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for dealing with the relaxation of the cable - stay steel strands during the vertical rotation of the arch rib, characterized in that: It includes the following steps: ①, Pre-position the arch rib (1). During the vertical rotation of the arch rib (1), multiple strands of cable-stayed steel strands are required, and the number of steel strands in a single cable-stayed strand is large. When each cable-stayed steel strand (3) passes through the groove of the single-row pulley (2) above the cable saddle (6), it will be arranged in layers, forming the upper cable-stayed steel strand (303), the middle cable-stayed steel strand (302), and the lower cable-stayed steel strand (301); at the beginning of the vertical rotation of the arch rib (1), the cable-stayed steel strand (3) moves along the arc formed by the surface of the pulley as the pulley rotates. At this time, the tensile forces P1 = P2 at both ends of the cable-stayed steel strand (3). As the vertical rotation of the arch rib (1) progresses, due to the differences in the moving track radii of the cable-stayed steel strands in each layer, while the cable-stayed steel strand rotates with the pulley, the lower cable-stayed steel strand (301) will generate relative displacement and slide along the pulley groove, and each pulley generates a sliding friction force F on the lower cable-stayed steel strand (301). i At this time, the tensile forces P1 = P2 + ∑F at both ends of the lower cable-stayed steel strand (301). i ; where ∑F i is the static friction force generated by the pulley on the lower cable-stayed steel strand (301). ②, Vertically rotate and lower the arch rib (1). As the vertical rotation angle of the arch rib (1) increases, the axial tension of the cable strand (3) gradually decreases. When the tension is less than the static friction force ∑F i i.e., P1 < ∑F i , at this time, the lower cable strands (301) at the front end of the cable tower (4) will not produce relative displacement and sliding along the pulley groove, and the lower cable strands (301) at the front end of the cable tower (4) will become slack; ③, Continuously vertically rotate and lower the arch rib (1). As the vertical rotation angle of the arch rib (1) continues to increase, the slack of the lower layer of the cable strands (301) at the front end of the cable tower (4) will gradually accumulate. At this time, the lowering of the arch rib (1) is controlled by the vertical rotation jack (7), and the lowering distance of the bundled cable strands (3) is generally 1 to 2 jack (7) strokes. At this time, the cable strands of the cable at the saddle (6) move in the reverse direction along the arc formed by the surface of the pulley as the pulley rotates, the friction force is in the reverse direction and P2 < ∑F i , the lower layer of the cable strands at the rear end of the cable tower (4) will not generate relative displacement and slide along the pulley groove. Since the moving distance of the lower layer of the cable strands is less than that of the upper layer of the cable strands, the slack lower layer of the cable strands of the bundled cable strands (3) at the front end of the cable tower (4) will be gradually tightened; ④, Vertically rotate and lift the arch rib, and tension the slack cable steel strands at the front end of the buckling tower (4). If the slack cable steel strands at the front end of the buckling tower (4) are not completely tensioned after lowering 1 - 2 strokes of the jacks (7), continue to vertically rotate and lift 1 - 2 strokes of the jacks (7) and then lower several times, and the slack cable steel strands at the front end of the buckling tower (4) can be tensioned. ⑤, Continuously vertically rotate and lift the arch rib. When the slack of the lower layer steel strands (301) of the cable at the front end of the buckling tower (4) gradually accumulates to a certain extent, perform the above steps ③ - ④ for the vertical rotation construction of the arch rib until the design position. ⑥, Consolidate the vertical rotation system of the arch rib.

2. The method for dealing with the relaxation of the cable steel strands during the vertical rotation of the arch rib according to claim 1, wherein: Before pre-positioning the arch rib (1), fix the buckling tower (4) on the base (8) of the vertical rotation device in advance, fix the saddle (6) at the top of the buckling tower (4), install multiple pulleys (2) on the saddle (6), install the vertical rotation hinge (5) on the base (8) of the vertical rotation device, install the arch rib (1) at the bottom on the vertical rotation hinge (5), connect one end of the cable steel strand (3) to the top of the arch rib (1), and connect the other end of the cable steel strand (3) to the jack (7) located on the base (8) of the vertical rotation device after passing through the pulley (2).

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