CN116446303B

CN116446303B - A method for simultaneous construction of single cantilever tower and beam of a steel truss cable-stayed bridge

Info

Publication number: CN116446303B
Application number: CN202310288532.9A
Authority: CN
Inventors: 王俊平; 李猛; 赵大伟; 贾晓峰; 孙燕荣; 王连同; 周立业; 亓泽霖
Original assignee: Jinan Urban Construction Group Co Ltd; Shandong Quanjian Engineering Testing Co Ltd; Jinan Municipal Engineering Construction Group Co Ltd; Shandong Huitong Construction Group Co Ltd; Shandong Huiyou Municipal Garden Group Co Ltd
Current assignee: Jinan Urban Construction Group Co Ltd; Shandong Quanjian Engineering Testing Co Ltd; Jinan Municipal Engineering Construction Group Co Ltd; Shandong Huitong Construction Group Co Ltd; Shandong Huiyou Municipal Garden Group Co Ltd
Priority date: 2023-03-23
Filing date: 2023-03-23
Publication date: 2026-02-13
Anticipated expiration: 2043-03-23
Also published as: CN116446303A

Abstract

This invention relates to the field of bridge construction technology, specifically to a method for simultaneous construction of a single cantilever tower and girder of a steel truss cable-stayed bridge. In this invention, during the upward construction of the tower column, the pier top segment is installed simultaneously, with longitudinal and transverse bridge-direction limits set. After the side span of the steel truss girder is erected, a tower crane is used to install a full-rotation crane on the side span segment, and the tower is constructed to the corresponding segment. As the tower continues to be constructed upwards, the steel truss girder is installed on the single cantilever side of the middle span, and the cable stays on the middle and side spans are symmetrically installed and tensioned until the entire bridge is closed. This invention allows for simultaneous construction of the tower and the single cantilever of the steel truss girder, solving the problems of high cost and slow progress associated with traditional construction methods.

Description

Synchronous construction method for Shan Xuanbei tower beams of steel truss girder cable-stayed bridge

Technical Field

The invention relates to the technical field of bridge construction, in particular to a synchronous construction method for a Shan Xuanbei tower beam of a steel truss girder cable-stayed bridge.

Background

The steel truss girder cable-stayed bridge is the most common bridge type of the large-span highway-railway dual-purpose cable-stayed bridge, and is favored by vast engineers due to the advantages of stable structural system, mature construction method, noninterference between highway layer and railway layer subareas and the like. In recent years, a large number of large-span highway-railway dual-purpose cable-stayed bridges such as Shangsu Tong Yangtze river highway-railway bridge, shangji Hangzhou railway turnip Yangtze river highway-railway bridge, copper tomb Yangtze river highway-railway bridge, white house temple Yangtze river bridge and the like are built successively and realize traffic, and good economic and social benefits are created. The construction method of the steel truss girder cable-stayed bridge is greatly influenced by the modeling, structural characteristics, topography, construction site conditions and the like of a cable-stayed tower, the overall construction method of the girder comprises a double-cantilever whole-section installation method, a double-cantilever loose splicing method, a pushing method, a shore side pushing mid-span cantilever loose splicing method and the like, and the construction method of the steel truss girder pier top internode comprises a whole-section hoisting method, a loose splicing sliding method and the like.

When the double-cantilever split-splicing method is adopted, two rotary cranes are required to be simultaneously put into, and the top position of the pier is required to be set with stronger temporary consolidation, so that on one hand, the temporary consolidation measure cost is increased, on the other hand, the girder construction difficulty is increased, and the favorable topography of the side span on the beach and polo area is not fully utilized.

When the traditional steel truss cable-stayed bridge tower beams are synchronously constructed, when the middle-span side steel truss girder segments are installed and the stay cables are tensioned, the main tower is closed, and the main defects are that the middle-span side steel truss girder segments can be installed after the cable tower is closed, the steel truss girder installation operation can not be simultaneously carried out when the cable tower construction is not realized, and the construction period is long.

Aiming at a steel truss girder cable-stayed bridge crossing a non-navigable river and having a main pier positioned in a beach polder area, a new construction method is required to be found to reduce the construction cost and accelerate the construction progress.

Disclosure of Invention

The invention provides a synchronous construction method for a Shan Xuanbei tower beam of a steel truss girder cable-stayed bridge, which aims to solve the defects in the prior art.

The invention is realized by the following technical scheme:

A synchronous construction method for a Shan Xuanbei tower beam of a steel truss girder cable-stayed bridge comprises the following steps:

The method comprises the steps of constructing a lower tower column, concrete brackets, a lower beam, auxiliary piers and side piers of a main pier cable tower, installing a pier-side bracket embedded part on the concrete surface in advance during construction of a main pier bearing platform and a tower seat, synchronously constructing a main pier cable tower section and the pier-side bracket, installing a temporary buttress at a side span part, and installing a side span side gantry crane.

And secondly, constructing a tower column in the main pier by adopting a hydraulic climbing die, installing a lower chord member between pier tops by adopting a crawler crane, arranging a sliding rail in the bridge direction, a vertical adjusting jack and a temporary cushion block, installing the lower chord member and a lower bridge deck system on the temporary pier tops on the side of the side span along the bridge direction, connecting the lower chord member and the lower bridge deck system into a whole by adopting high-strength bolts, lifting the lower chord member and removing the sliding rail in the bridge direction after the horizontal dragging jack and the finish rolling screw steel are dragged to a designated position, dropping the lower chord member onto a permanent support, and bolting and fixing the lower chord member and an upper steel plate of the permanent support.

And step three, sequentially installing a pier top internode straight web member, an inclined web member, an upper chord member, an upper middle bridge surface system and an inclined strut, installing a transverse bridge direction sliding rail on a lower cross beam of a cable tower, sliding the auxiliary truss rod to a designated position along the transverse bridge direction by adopting a horizontal dragging jack and finish rolling screw steel, adjusting the position of the auxiliary truss rod by adopting a vertical adjusting jack, connecting with the inclined strut, and installing an upper bridge surface system to complete the installation of the whole pier top internode steel member.

And fourthly, sequentially installing the rest steel truss members at the middle span and the side span of the pier top internode by adopting a crawler crane, and installing forward limit and transverse limit on the forward and transverse sides of the pier top permanent support at the bottom surface of the lower chord of the steel truss.

And fifthly, constructing a tower column on the cable tower, installing a first-section steel anchor beam and a cable guide pipe, and adopting a gantry crane to install the steel truss beam from the middle span to the side span until the main bridge side span steel truss beam is completely installed.

And step six, continuing to construct the cable tower upwards, adopting a tower crane to install a rotary crane at the side span position, and installing a girder loading trolley on the upper bridge deck.

And when the hydraulic climbing formwork climbs and the outlet end of the cable duct is exposed and has the installation condition of the stay cable, the first section steel truss girder at the midspan side is installed by adopting a rotary crane, the first section stay cable at the midspan side and the first section stay cable at the side are symmetrically installed, and the pier bracket is tensioned and removed.

And eighth, along with the upward construction of the cable tower, continuously installing the steel truss girder on the mid-span side in a single cantilever method, symmetrically tensioning corresponding stay cables on the mid-span side and the side span side, removing the temporary buttress under the steel truss girder in advance before tensioning the side span side stay cables, and removing the hydraulic climbing formwork after the cable tower is capped.

And step nine, the main bridge continues cantilever construction until closure, the forward limit and the transverse limit of the main pier are released, the angle, the elevation and the plane deviation of the steel trusses at the two ends of the closure opening are adjusted by adjusting the cable force of the stay cable, and the closure section steel trusses are installed by using a bridge deck crane.

And step ten, adjusting the cable force of the stay cable, installing a steel truss girder damper, and applying the damper to a bridge deck system and an accessory structure.

As a preferable scheme:

In the second step, the forward-bridge-direction sliding track is made of profile steel, the forward-bridge-direction sliding track is arranged along the center of the lower chord member, the elevation of the top of the forward-bridge-direction sliding track is 5-10cm higher than that of the permanent support, the bottom of the forward-bridge-direction sliding track is supported on the top surface of a concrete bracket or a pier side support distribution beam by adopting a steel plate, both ends of the permanent support are provided with temporary cushion blocks and vertical adjusting jacks, a tensioning counterforce seat is arranged on the top of the middle-span side forward-bridge-direction sliding track, a fixed end of finish-rolling deformed steel bar is anchored on a customizing tool at the end part of the lower chord member, and the horizontal dragging jacks are used for tensioning the finish-rolling deformed steel bar to realize forward-bridge-direction sliding of the lower chord member and a lower bridge panel.

In the third step, the pier top central internode straight web member, the upper chord member, the upper bridge deck system and the diagonal brace are all hoisted in place through the crawler crane, and the auxiliary truss rod is in place through a transverse sliding and dragging method.

In the third step, transverse bridge direction sliding rails are respectively arranged on the top surface of the lower cross beam of the cable tower, after the cable tower slides to a designated position, the vertical adjusting jack is adopted to jack up the auxiliary truss rod, then the transverse bridge direction sliding rails are removed, and the cable tower falls down to be connected with the inclined stay bars.

In the fifth step, before the steel truss reaches the next temporary buttress, the steel truss needs to be lifted by using the vertical adjusting jacks on the previous temporary buttress, and the lifting height is consistent with the downwarping height of the steel truss between the two temporary buttresses, so that the steel truss can be smoothly penetrated.

In the seventh step, the installation condition of the stay cable is that the tower column section where the first section of the stay cable steel anchor beam on the side of the middle span and the side span is located has completed annular prestress construction, the concrete age of the tower column section meets the 28-day requirement, 2-3 tower column sections are constructed above the tower column section, and after the hydraulic climbing formwork is climbed, the cable guide pipe is exposed out of the outer surface of the tower column.

In the step nine, when the cable tower is capped, the cable is required to complete 1/3-1/2 of the total number of installation tensioning operations.

The cable tower and the steel truss single-side cantilever construction are simultaneously carried out, so that the problems of high construction cost and slow progress of the traditional construction scheme are solved, new designs are carried out at each construction stage, the construction cost can be obviously reduced, the construction progress is quickened, and the total construction cost of the engineering is saved.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a longitudinal section layout view of a cable-stayed bridge with steel trusses according to the embodiment;

FIG. 2 is a schematic diagram of a cross-sectional structure of a cable tower of the cable-stayed bridge of the steel truss girder of the embodiment;

FIG. 3 is a schematic diagram of a longitudinal section structure of a cable tower of the cable-stayed bridge with steel truss girder according to the embodiment;

FIG. 4 is a schematic view of the structure of the steel truss girder according to the present embodiment;

FIG. 5 is a schematic diagram showing a construction step of the present embodiment;

FIG. 6 is a schematic view of a cross section of a bottom chord member and a bottom deck assembly of a center section of a second pier top in this embodiment;

FIG. 7 is a schematic view of a bottom chord and deck assembly of a second pier top center section in accordance with the present embodiment;

FIG. 8 is a schematic diagram of the step two pier top center internode lower chord and lower deck system slippage in this embodiment;

FIG. 9 is a schematic view of the adjustment of the lower chords and the lower deck system drop beams of the center section of the second pier top in this embodiment;

FIG. 10 is a schematic view of the mounting cross section of the center internode straight web member, upper chord, etc. of the three pier top in this embodiment;

FIG. 11 is a schematic view of a vertical section of a three pier top center section straight web member, an upper chord member, etc. in this embodiment;

FIG. 12 is a schematic cross-sectional view of a sliding installation of a center section of a side truss rod at a top of a three pier in the present embodiment;

FIG. 13 is a schematic view of a sliding installation longitudinal section of a center section auxiliary truss rod of a three pier top in the embodiment;

FIG. 14 is a step four schematic diagram of the present embodiment;

FIG. 15 is a schematic view of the mounting cross section of the remaining steel truss members between four pier top joints in the step of this embodiment;

FIG. 16 is a fifth step diagram of the present embodiment;

FIG. 17 is a diagram illustrating a sixth step of the present embodiment;

FIG. 18 is a seventh schematic diagram of the step of the present embodiment;

FIG. 19 is a schematic diagram of a step eight of the present embodiment;

FIG. 20 is a schematic view of a maximum cantilever state of a nine-steel truss girder according to the step of the present embodiment;

fig. 21 is a schematic construction diagram of a closure section of a nine-steel truss girder in the step of this embodiment.

In the figure, 1, a cable tower, 2, a lower tower column, 3, a concrete bracket, 4, a lower cross beam, 5, a middle tower column, 6, an upper tower column, 7, a permanent support, 8, a steel truss girder, 9, a cable guide, 10, a steel anchor beam, 11, a lower chord, 12, an upper chord, 13, a lower bridge deck system, 14, an upper middle bridge deck system, 15, a secondary truss rod, 16, an upper bridge deck system, 17, a straight web member, 18, a diagonal web member, 19, a diagonal brace, 20, an auxiliary pier, 21, a side pier, 22, a hydraulic climbing die, 23, a tower crane, 24, a pier side bracket, 25, a temporary pier, 26, a gantry crane, 27, a forward bridge sliding track, 28, a vertical adjusting jack, 29, a temporary cushion block, 30, a crawler crane, 31, a counter-force seat, 32, a horizontal drag jack, a finish rolling screw, 34, a transverse bridge sliding track, 35, a gyrator, 36, a girder trolley, 37, a diagonal bridge, 38, a forward bridge, 39, a transverse bridge girder, and a limit girder.

Detailed Description

The present invention is described in further detail below with reference to the drawings to enable those skilled in the art to practice the invention by referring to the description.

It should be noted that, in the following embodiments, unless otherwise specified, the experimental methods are conventional methods, and the reagents and materials are commercially available, unless otherwise specified, and in the description of the present invention, the terms "horizontal", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements to be referred to must have specific orientations, be configured and operated in specific orientations, and therefore are not to be construed as limiting the present invention.

As shown in fig. 1, the main bridge of the steel truss cable-stayed bridge of the embodiment is a double-tower five-span steel truss cable-stayed bridge, the main bridge is not navigable across a water area, and the main pier, the auxiliary pier 20 and the side pier 21 are all positioned in a shore side beach polepiece area and are not interfered by flood.

As shown in fig. 2-4, the cable-stayed bridge tower 1 of the steel truss girder 8 is in a bottle shape as a whole, and the cable tower 1 comprises a lower tower column 2, a concrete bracket 3, a lower cross beam 4, a middle tower column 5 and an upper tower column 6. The steel truss girder 8 is in an inverted trapezoid shape, and the steel truss girder 8 comprises a lower chord member 11, an upper chord member 12, a lower bridge deck system 13, an upper middle bridge deck system 14, an auxiliary truss rod 15, an upper bridge deck system 16, a straight web member 17, an inclined web member 18 and an inclined strut member 19. The lower tower column 2 of the cable tower 1 inclines outwards, the middle tower column 5 inclines inwards, the upper tower column 6 is vertically upwards after closure, and gradually upwards reaches the tower crown along the cross section. The inner side wall of the lower tower column 2 is provided with a concrete bracket 3, a permanent support 7 is arranged on the concrete bracket 3, and the concrete bracket 3 is a vertical main stress member of the steel truss girder 8. The number of the lower cross beams 4 of the cable towers 1 is 2, a certain interval exists between the cross beams, the steel truss beam 8 pier top section straight web members 17 penetrate through the lower cross beams 4 of the two cable towers 1, the upper chord member 12, the auxiliary truss rod 15, the upper middle bridge surface system 14 and the upper bridge surface system 16 are all positioned above the lower cross beams 4 of the cable towers 1, and the steel anchor beam 10 and the cable guide pipe 9 are arranged at the upper tower column 6 section of the cable tower 1.

The synchronous construction method of the Shan Xuanbei tower beams of the steel truss girder cable-stayed bridge comprises the following steps:

Step one, as shown in fig. 5, constructing a lower tower column 2, a concrete bracket 3, a lower cross beam 4, an auxiliary pier 20 and an edge pier 21 of a main pier cable tower 1, and installing a pier side bracket 24 embedded part on the concrete surface in advance during construction of a main pier bearing platform and a tower seat, synchronously constructing a main pier cable tower 1 section and the pier side bracket 24, installing an edge-span part temporary supporting pier 25 and installing an edge-span side gantry crane 26.

6-9, Constructing a tower column 5 in the main pier by adopting a hydraulic climbing die 22, adopting a crawler crane 30 to install a pier top internode lower chord 11 along a bridge-direction sliding rail 27, adopting a vertical adjusting jack 28 and adopting a temporary cushion block 29, installing the lower chord 11 and a lower bridge deck system 13 on the side span side temporary buttress 25 along the bridge-direction sliding rail 27, adopting high-strength bolts to connect the lower chord 11 and the lower bridge deck system into a whole, adopting a horizontal dragging jack 32 and finish rolling screw steel 33 to drag to a designated position, lifting the lower chord 11, removing the along bridge-direction sliding rail 27, dropping the lower chord 11 onto a permanent support 7, and bolting and fixing the lower chord 11 with an upper steel plate of the permanent support 7.

In the second step, the forward-bridge sliding rail 27 is made of profile steel, the forward-bridge sliding rail 27 is arranged along the center of the lower chord 11, the top elevation of the forward-bridge sliding rail 27 is 5-10cm higher than that of the permanent support 7, steel plates are adopted to support the bottom of the rail to be on the top surface of the concrete bracket 3 or a pier side support distribution beam, temporary cushion blocks 29 and vertical adjusting jacks 28 are arranged at two ends of the permanent support 7, a tensioning counterforce seat 31 is arranged at the top of the midspan side forward-bridge sliding rail 27, the fixed end of a finish-rolling deformed steel 33 is anchored on a custom-made tool at the end part of the lower chord 11, and the horizontal traction jack 32 is adopted to finish-roll deformed steel 33, so that the forward-bridge sliding of the lower chord 11 and a lower bridge panel is realized.

10-13, Sequentially installing a pier top internode straight web member 17, an inclined web member 18, an upper chord member 12, an upper middle bridge surface system 14 and an inclined strut 19, installing a transverse bridge direction sliding rail 34 on the lower beam 4 of the cable tower 1, sliding the auxiliary truss rod 15 to a designated position along the transverse bridge direction by adopting a horizontal dragging jack 32 and a finish rolling screw steel 33, adjusting the position of the auxiliary truss rod 15 by adopting a vertical adjusting jack 28, connecting with the inclined strut 19, installing an upper bridge surface system 16, and completing the installation of the whole pier top internode steel member.

In the third step, the pier top central internode straight web member 17, the inclined web member 18, the upper chord member 12, the upper bridge deck system, the inclined strut 19 and other components can be lifted and positioned through the crawler 30, the auxiliary truss rod 15 is affected by the inward inclination of the middle tower column 5, the lifting and the positioning cannot be realized, and the transverse sliding and dragging method is adopted for positioning.

In the third step, a transverse bridge direction sliding rail 34 is respectively arranged along the top surface of the lower cross beam 4 of the cable tower 1, after the cable tower is slid to a designated position, the vertical adjusting jack 28 is adopted to jack up the auxiliary truss rod 15, then the transverse bridge direction sliding rail 34 is removed, and the cable tower falls down to be connected with the diagonal brace 19.

And fourthly, as shown in figures 14-15, sequentially installing the rest steel truss beam 8 components on the middle span and the side span of the pier top by adopting a crawler crane 30. And the pier top permanent support 7 is arranged on the bottom surface of the lower chord 11 of the steel truss girder 8 along the bridge direction and at the two sides along the transverse bridge direction, and a forward bridge direction limit 38 and a transverse bridge direction limit 39 are arranged.

And fifthly, as shown in figure 16, constructing a tower column 6 on the cable tower 1, installing a first-section steel anchor beam 10 and a cable guide pipe 9, and installing the steel truss beam 8 from the middle span to the side span by adopting a gantry crane 26 until the main bridge side span steel truss beam 8 is completely installed.

In the fifth step, before the steel truss girder 8 reaches the next temporary buttress 25, the steel truss girder 8 needs to be lifted by using the vertical adjusting jacks 28 on the previous temporary buttress 25, and the lifting height is consistent with the downwarping height of the steel truss girder 8 between the two temporary buttresses 25, so that the steel truss girder 8 can be smoothly passed through holes.

Step six, as shown in fig. 17, the cable tower 1 continues to be constructed upwards, a rotary crane 35 is installed at the side span position by adopting a tower crane 23, and a girder loading trolley 36 is installed on the upper bridge deck.

And step seven, as shown in figure 18, the cable tower 1 continues to be constructed upwards by adopting the hydraulic climbing mould 22, and after entering an anchor cable area, the steel anchor beam 10 and the cable guide pipe 9 are sequentially installed from bottom to top, when the hydraulic climbing mould 22 climbs, the outlet end of the cable guide pipe 9 is exposed and has the installation condition of the stay cable 37, the first section steel truss beam 8 of the first section on the midspan side is installed by adopting the rotary crane 35, the first section stay cable 37 on the midspan side and the first section stay cable 37 on the side are symmetrically installed, and the pier-side bracket 24 is tensioned and removed.

In the seventh step, the first section stay cable 37 on the middle span side and the side span side is installed under the condition that the section of the tower column where the steel anchor beam 10 of the first section stay cable 37 on the middle span side and the side span side is located has completed the circumferential prestress construction, the concrete age of the section of the tower column meets the requirement of 28 days, 2-3 sections of the tower column have been constructed above the section of the tower column, and after the hydraulic climbing mould 22 climbs, the cable guide pipe 9 is exposed on the outer surface of the tower column. The first section of the stay cable 37 on the midspan and side of the side span is synchronously threaded and tensioned at 4 points on the upstream side and the downstream side.

And step eight, as shown in figure 19, along with the upward construction of the cable tower 1, continuously installing the steel truss girder 8 on the mid-span side in a single cantilever method, symmetrically tensioning corresponding stay cables 37 on the mid-span side and the side-span side, and removing the temporary buttress 25 under the steel truss girder 8 in advance before tensioning the side-span side stay cables 37, and removing the hydraulic climbing formwork 22 after capping the cable tower 1.

Step nine, as shown in figures 20-21, the cantilever construction of the main bridge is continued until closure, the forward limit 38 and the transverse limit 39 of the main pier are released, the angle, the elevation and the plane deviation of the steel trusses 8 at the two ends of the closure opening are adjusted by adjusting the cable force of the stay cable 37, and the bridge deck crane is used for installing the closure section steel trusses 40.

When the cable tower 1 is capped, the stay cables 37 are required to complete 1/3-1/2 of the total number of installation tensioning operations, and the installation of the rest stay cables 37 and the steel truss girder 8 is not affected by the construction of the cable tower 1.

And step ten, adjusting the cable force of the stay cable 37, installing a damper of the steel truss girder 8, and applying the damper to a bridge deck system and an accessory structure.

Although embodiments of the present invention have been disclosed above, it is not limited to the details and embodiments shown and described, it is well suited to various fields of use for which the invention would be readily apparent to those skilled in the art, and accordingly, the invention is not limited to the specific details and illustrations shown and described herein, without departing from the general concepts defined in the claims and their equivalents.

Claims

1. A method for simultaneous construction of a single cantilever tower and beam of a steel truss cable-stayed bridge, comprising the following steps:

Step 1: Construct the main pier tower (1), lower tower column (2), concrete corbel (3), lower crossbeam (4), auxiliary pier (20), and side pier (21); When constructing the main pier foundation and tower base, install the pre-embedded parts of the pier side bracket (24) on the concrete surface in advance. The main pier tower (1) segment and the pier side bracket (24) are constructed simultaneously. Install the temporary support pier (25) at the side span and install the side span gantry crane (26).

Step 2: The main pier tower column (5) is constructed using hydraulic climbing formwork (22). The lower chord (11) of the pier top section is installed using crawler crane (30) along the bridge direction sliding track (27), vertical adjusting jacks (28), and temporary pads (29). The lower chord (11) and the lower bridge deck system (13) are installed on the bridge direction sliding track (27) on the top of the temporary support pier (25) on the side span. They are connected into a whole using high-strength bolts. After being dragged to the designated position using horizontal dragging jacks (32) and precision rolled threaded steel (33), the lower chord (11) is lifted and the bridge direction sliding track (27) is removed. The lower chord (11) is lowered to the permanent support (7) and the lower chord (11) is bolted to the steel plate on the permanent support (7).

Step 3: Install the straight web members (17), diagonal web members (18), upper chord members (12), upper and middle bridge deck system (14), and diagonal bracing members (19) in sequence at the top of the pier. Install the transverse sliding track (34) on the lower crossbeam (4) of the tower (1). Use horizontal drag jacks (32) and precision rolled threaded steel bars (33) to slide the secondary truss (15) to the designated position along the transverse direction. Use vertical adjustment jacks (28) to adjust the position of the secondary truss (15) and connect it with the diagonal bracing members (19). Install the upper bridge deck system (16) to complete the installation of the entire steel components at the top of the pier.

Step 4: Use a crawler crane (30) to install the remaining steel truss beams (8) on the middle and side spans of the pier top section in sequence; install the longitudinal limiters (38) and transverse limiters (39) on both sides of the permanent support (7) at the bottom of the lower chord (11) of the steel truss beam (8) in the longitudinal and transverse directions.

Step 5: Construct the upper tower column (6) of the cable tower (1), install the first section of steel anchor beam (10) and cable guide (9); use a gantry crane (26) to install the steel truss beam (8) from the middle span to the side span until all the steel truss beams (8) of the main bridge side span are installed;

Step 6: The tower (1) continues to be constructed upwards. A slewing crane (35) is installed at the side span position using a tower crane (23), and a beam transport trolley (36) is installed on the upper bridge deck.

Step 7: The cable tower (1) continues to be constructed upward using hydraulic climbing formwork (22). After entering the anchor cable area, steel anchor beams (10) and cable guide pipes (9) are installed sequentially from bottom to top. When the hydraulic climbing formwork (22) is ascending, the outlet end of the cable guide pipe (9) is exposed and the conditions for installing the stay cables (37) are met, the first segment of the steel truss beam (8) on the middle span side is installed using a rotary crane (35), and the first segment of the stay cables (37) on the middle span side and the first segment of the stay cables (37) on the side span side are symmetrically installed and tensioned. The brackets (24) beside the pier are then removed.

Step 8: As the tower (1) is constructed upward, continue to install the steel truss beam (8) towards the mid-span side using the single cantilever method, and symmetrically tension the corresponding stay cables (37) on the mid-span side and the side span side. Before tensioning the stay cables (37) on the side span side, remove the temporary support pier (25) under the steel truss beam (8) in advance. After the tower (1) is capped, remove the hydraulic climbing formwork (22).

Step 9: Before the main bridge is closed, the longitudinal (38) and transverse (39) limit of the main pier is released. The angle, elevation and plane deviation of the steel truss beams (8) at both ends of the closure section are adjusted by adjusting the cable force of the stay cable (37). The steel truss beams (40) of the closure section are installed using the bridge deck crane.

Step 10: Adjust the cable tension of the stay cables (37), install the damper of the steel truss (8), and construct the bridge deck system and ancillary structures.

2. The method for synchronous construction of single cantilever tower beam of steel truss cable-stayed bridge according to claim 1, characterized in that: in step two, the sliding track (27) along the bridge direction is made of steel and is arranged along the center of the lower chord (11) along the bridge direction. The top elevation of the sliding track (27) along the bridge direction is 5-10cm higher than the permanent support (7). The bottom of the sliding track (27) along the bridge direction is supported by steel plates on the top surface of the concrete corbel (3) or the distribution beam of the support next to the pier. Temporary pads (29) and vertical adjustment jacks (28) are set at both ends of the permanent support (7). The tensioning reaction seat (31) is set on the top of the sliding track (27) along the bridge direction on the middle span side. The fixed end of the fine rolled threaded steel (33) is anchored to the customized tooling at the end of the lower chord (11). The fine rolled threaded steel (33) is tensioned by the horizontal drag jack (32) to realize the sliding of the lower chord (11) and the lower bridge deck along the bridge direction.

3. The method for synchronous construction of single cantilever tower beam of steel truss cable-stayed bridge according to claim 1, characterized in that: in step three, the straight web member (17), upper chord member (12), upper bridge deck system and diagonal brace (19) of the central section of the pier top are all hoisted into place by crawler crane (30), and the secondary truss member (15) is placed in place by lateral sliding and dragging method.

4. The method for synchronous construction of single cantilever tower beam of steel truss cable-stayed bridge according to claim 1, characterized in that: in step three, a transverse bridge sliding track (34) is set on the top surface of the lower crossbeam (4) of the tower (1). After sliding to the designated position, the secondary truss (15) is lifted by a vertical adjusting jack (28) and then the transverse bridge sliding track (34) is removed, and the beam is lowered and connected with the diagonal brace (19).

5. The method for synchronous construction of single cantilever tower beam of steel truss cable-stayed bridge according to claim 1, characterized in that: in step five, before the steel truss beam (8) reaches the next set of temporary supports (25), the vertical adjustment jacks (28) on the previous set of temporary supports (25) are used to lift the steel truss beam (8), and the lifting height is consistent with the downward deflection height of the steel truss beam (8) between the two temporary supports (25), so as to ensure that the steel truss beam (8) can pass through the hole smoothly.

6. The method for synchronous construction of single cantilever tower beam of steel truss cable-stayed bridge according to claim 1, characterized in that: in step seven, the installation conditions of the cable stay (37) are that the circumferential prestressing construction of the tower column segment where the first segment of cable stay (37) steel anchor beam (10) is located on the middle span and side span has been completed, the concrete age of the tower column segment meets the requirement of 28 days, and 2-3 tower column segments above the tower column segment have been constructed. After the hydraulic climbing formwork (22) is raised, the cable guide (9) is exposed on the outer surface of the tower column.

7. The method for synchronous construction of single cantilever tower beam of steel truss cable-stayed bridge according to claim 1, characterized in that: in step nine, when the tower (1) is capped, the cable stays (37) need to complete 1/3 to 1/2 of the total number of installation and tensioning operations.