Steel box core concrete combined cable tower construction method

Abstract

The application belongs to the technical field of cable tower construction, and particularly relates to a steel box core concrete combined cable tower construction method, which comprises the following steps: step one, installation of a combination section positioning support; step two, installation of combination section reinforcing steel bars; step three, hoisting of a steel tower reference section and adjustment of positioning; step four, pouring of combination section concrete; and step five, steel tower construction on the upper tower. The steel box core concrete combined cable tower construction method, through steps one to five, pre-processes the steel box in sections when constructing the steel box core concrete combined cable tower, then hoists and constructs the sections in sections, reduces the hoisting weight of the steel structure, and precisely aligns the hoisted and assembled steel tower section with the fixed steel tower section that has been installed and positioned through a positioning adjustment mechanism, thereby solving the problems of high steel structure hoisting weight and high butt joint difficulty in the existing steel box core concrete combined cable tower construction, and affecting the steel tower construction weld quality.

Description

Technical Field

[0001] This invention relates to the field of cable tower construction technology, and in particular to a construction method for a steel box core concrete composite cable tower. Background Technology

[0002] With the rapid development of my country's bridge construction in recent years, super-long-span bridges and irregularly shaped bridge towers have emerged in large numbers, with more innovative structural designs. At the same time, the scale and construction difficulty of these projects have also increased significantly. The concrete tower-steel anchor box structure is a traditional form of cable-stayed tower anchoring structure, but it suffers from large local stress differences, making it prone to concrete cracking and posing significant challenges to the safety and quality control of concrete construction. The steel box-core concrete composite cable-stayed tower can effectively improve structural stiffness and fully utilize the differences in mechanical properties between steel and concrete to achieve coordination and unity of overall and local stresses in the cable-stayed tower anchoring system.

[0003] However, in actual construction, the construction of steel box core concrete composite cable towers faces problems such as heavy steel structure lifting and high connection difficulty, which affects the quality of steel tower welds. Therefore, a construction method for steel box core concrete composite cable towers is needed. Summary of the Invention

[0004] Based on the existing technical problems in the construction of steel box core concrete composite cable towers, such as the heavy lifting capacity of the steel structure and the high difficulty of docking, which affect the quality of welds in the steel tower construction, this invention proposes a construction method for steel box core concrete composite cable towers.

[0005] The present invention proposes a construction method for a steel-box core concrete composite cable tower, comprising the following steps:

[0006] Step 1: Install the segment positioning bracket;

[0007] Step 2: Installation of reinforcing steel bars in the connecting section;

[0008] Step 3: Hoisting and positioning the steel tower reference section;

[0009] Step 4: Concrete pouring for the joint section;

[0010] Step 5: Construction of the upper steel tower.

[0011] Preferably, the construction of the upper steel tower specifically includes the following steps:

[0012] S1. The steel tower column is divided into ten segments, T1 to T10, based on its height. Considering the on-site hoisting and welding conditions, the steel tower column is divided into 33 sections for hoisting. The maximum hoisting weight is 311t. When the XGT15000-600S tower crane has a lifting width of 35m, the lifting height is 298m, and the lifting weight is 407.9t, which is greater than 311t, thus meeting the lifting weight requirements.

[0013] S2. Construction of the upper tower column T1 section: The steel tower T1 section is divided into 4 pieces for on-site hoisting. The bottom T1 section and the pressure-bearing section are combined into 1 piece as the benchmark section for steel tower construction. It is constructed simultaneously with the steel-concrete composite section 39# tower column. The remaining T1-S, T1-H, and T1-M blocks will be constructed after the composite section is completed.

[0014] S3. Installation of the upper tower column Tn+1 section steel tower, which includes the hoisting and construction of steel tower sections T2 to T10;

[0015] Specifically, the installation of each section of the steel tower from T2 to T9 is carried out in three or four pieces. First, the core block is hoisted, and then the side and middle span steel tower sections are installed. The installation cycle is as follows: steel tower section hoisting → steel tower precise positioning, high bolting, and welding → core area reinforcement and concrete pouring → cyclic construction.

[0016] The lifting equipment for the T1 to T9 standard steel tower sections is specially designed, with a maximum lifting weight of 311.11t and a rated load capacity of 320t. The lifting equipment is adjusted laterally via the hydraulic jack and longitudinally via the screw rods to adjust the lateral and longitudinal spacing of the lifting points. When lifting the steel tower sections, the structural center of gravity is accurately calculated using a model, and then the arrangement of the lifting points is adjusted to make the center of gravity coincide with the center of the hook, thus achieving stable lifting.

[0017] The construction steps for hoisting and aligning standard sections of the steel tower are as follows:

[0018] Step 1: Calculate the center of gravity of the standard section of the steel tower and draw the relative position of the lifting lugs to the center of gravity. Adjust the lifting point position of the 320t lifting tool so that the main lifting point on the lifting tool coincides with the center of gravity of the steel tower section, the lower lifting point corresponds to the lifting lugs, and the lifting point is connected.

[0019] Step 2: The XGT15000-600S tower crane is used to lift the steel tower slowly by graded loads. After the tower is 10cm away from its original support surface, a special inspection is carried out on the levelness of the steel tower and the condition of the lifting equipment. After the inspection is passed, the lifting continues.

[0020] Step 3: Slowly raise the steel tower to a distance of 1m from the top surface of the previous section, rotate the tower crane boom, adjust the lifting width, and hoist the steel tower to the design position directly above it, and then align it.

[0021] Step 4: When the distance between the bottom of the steel tower to be lifted and the already installed steel tower differs by 1m in each direction, first guide the steel tower to lower in the correct direction using two guide chains for rough positioning, and then continue to lower the steel tower slowly.

[0022] Step 5: When the steel tower is about to be lowered to the design position, the positioning is adjusted by multiple positioning adjustment mechanisms. Then, the core block is positioned first by connecting the vertical matching parts, lateral limiting parts and positioning vertical ribs set on the steel tower. The positioning is carried out at night, and then the side blocks are positioned.

[0023] The T10 segment was hoisted using high-strength ring slings and lifting lugs.

[0024] S4. On-site welding of steel towers, including determining the welding work content, welding methods and selection of welding materials, bridge site welding and welding of main welds;

[0025] S5. Steel tower surface coating;

[0026] S6. Reinforcement construction in the core area;

[0027] S7. Concrete construction in the core area;

[0028] S8. Intelligent construction of steel towers.

[0029] Preferably, the welding materials used in the on-site welding of the steel tower include welding rods of type E5015-G (φ4.0), solid welding wire of type G55A4UC1ZSN2 (φ1.2), and flux-cored welding wire of type T494T1-1C1AUH5.

[0030] Preferably, the positioning adjustment mechanism includes a first fixed connecting seat and a second fixed connecting seat, the surfaces of the first fixed connecting seat and the second fixed connecting seat being fixedly connected to the surface of the fixed steel tower segment and the surface of the hoisted and assembled steel tower segment, respectively.

[0031] Preferably, the surfaces of the first fixed connecting seat and the second fixed connecting seat are both H-shaped. The inner walls of the first fixed connecting seat and the second fixed connecting seat are respectively fixedly connected to the first adapter seat and the second adapter seat by bolts. The inner walls of the first adapter seat and the second adapter seat are respectively rotatably connected to the support frame and the tensioning hydraulic cylinder by pins.

[0032] Preferably, the tensioning hydraulic cylinder includes a tensioning hydraulic rod, one end of which is rotatably connected to one end of the support frame via a pin.

[0033] Preferably, the support frame is rotatably connected to one end of the tensioning hydraulic rod, and two symmetrically distributed fixed shafts are fixedly connected to the surface of the two fixed shafts. A steering support column is slidably sleeved on the surface of the two fixed shafts. A locking groove is formed on the surface of the steering support column, and a locking tooth ring is fixedly connected to the inner wall of the locking groove.

[0034] Preferably, a stop gear is fixedly sleeved on the surface of the fixed shaft, and the surface of the stop gear meshes with the inner wall of the locking gear ring.

[0035] Preferably, one end of one of the fixed shafts is fixedly connected to a support plate, a pressure spring is sleeved on the surface of the fixed shaft, one end of each of the two pressure springs is fixedly connected to the surface of each of the two steering support columns, and the other end of each of the two pressure springs is fixedly connected to the surface of the support frame and the surface of the support plate, respectively.

[0036] Preferably, an auxiliary hydraulic cylinder is hinged to the surface of the steering support column. The auxiliary hydraulic cylinder includes an auxiliary hydraulic rod, one end of which is hinged to a tensioning auxiliary block. The surface of the tensioning auxiliary block is rotatably connected to the surfaces of the two steering support columns via a rotating shaft.

[0037] The beneficial effects of this invention are as follows:

[0038] 1. By setting steps one through five, the steel box is pre-processed into sections during the construction of the steel box core concrete composite cable tower, and then the sections are hoisted and constructed in sections. This reduces the lifting weight of the steel structure. Furthermore, the positioning and adjustment mechanism is used to accurately align the hoisted and assembled steel tower sections with the fixed steel tower sections that have already been installed and positioned. This solves the problems of heavy steel structure lifting and high docking difficulty in the existing construction of steel box core concrete composite cable towers, which affect the quality of welds in the steel tower construction.

[0039] 2. By setting up a positioning and adjustment mechanism, during the assembly and welding of steel tower segments, the positioning and adjustment mechanism pushes and tensions the hoisted and assembled steel tower segments, thereby achieving rapid horizontal adjustment and alignment between the hoisted and assembled steel tower segments and the fixed steel tower segments, thus reducing the difficulty of docking and achieving better welding results for steel tower construction. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a construction method for a steel-box core concrete composite cable tower proposed in this invention;

[0041] Figure 2 This is a plan view of the positioning support for segment T1 in a construction method for a steel-box core concrete composite cable tower proposed in this invention.

[0042] Figure 3 This invention proposes a construction method for a steel-box core concrete composite cable tower. Figure 2 Schematic diagram of direction 1-1;

[0043] Figure 4 This invention proposes a construction method for a steel-box core concrete composite cable tower. Figure 2 Schematic diagram of direction 2-2 in the middle;

[0044] Figure 5 This is a diagram showing the arrangement of vertical ribs on the side blocks of a steel-box core concrete composite cable tower construction method proposed in this invention.

[0045] Figure 6 This is a diagram showing the vertical rib arrangement of the core block in a construction method for a steel-box core concrete composite cable tower proposed in this invention.

[0046] Figure 7 This is a structural diagram of the side block and core block vertical rib plate of a steel box core concrete composite cable tower construction method proposed in this invention;

[0047] Figure 8 This is a schematic diagram of the positioning and adjustment mechanism structure of a steel box core concrete composite cable tower construction method proposed in this invention;

[0048] Figure 9 This is a three-dimensional view of the positioning and adjustment mechanism structure of a steel box core concrete composite cable tower construction method proposed in this invention.

[0049] Figure 10 This is a perspective view of the first fixed connection seat structure of a construction method for a steel box core concrete composite cable tower proposed in this invention;

[0050] Figure 11 This is a side view of the first fixed connection seat structure of a construction method for a steel box core concrete composite cable tower proposed in this invention;

[0051] Figure 12 This is a three-dimensional view of the first transition seat structure of a steel box core concrete composite cable tower construction method proposed in this invention;

[0052] Figure 13 This invention proposes a construction method for a steel-box core concrete composite cable tower. Figure 12 Enlarged view of the structure at point A in the middle.

[0053] In the figure: 1. Positioning and adjusting mechanism; 101. First fixed connecting seat; 102. Second fixed connecting seat; 103. First adapter seat; 104. Second adapter seat; 105. Support frame; 106. Tensioning hydraulic cylinder; 107. Tensioning hydraulic rod; 108. Fixed shaft; 109. Steering support column; 1010. Locking groove; 1011. Locking gear ring; 1012. Stop gear; 1013. Support plate; 1014. Pressure spring; 1015. Auxiliary hydraulic cylinder; 1016. Auxiliary hydraulic rod; 1017. Tensioning auxiliary block. Detailed Implementation

[0054] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0055] Reference Figures 1-13 A construction method for a steel-box core concrete composite cable tower includes the following steps:

[0056] Step 1: Install the joint section positioning bracket.

[0057] Step 2: Install the reinforcing steel bars in the connecting section.

[0058] Step 3: Hoist the steel tower reference section and adjust its positioning.

[0059] Step 4: Concrete pouring for the joint section.

[0060] Step 5: Construction of the upper steel tower.

[0061] Furthermore, the construction of the upper steel tower specifically includes the following steps:

[0062] S1. The steel tower column is divided into sections, with the column height divided into ten sections from T1 to T10. Considering the on-site hoisting and welding conditions, the steel tower column is divided into 33 sections for hoisting. The maximum hoisting weight is 311t. When the XGT15000-600S tower crane has a lifting width of 35m, the lifting height is 298m, and the lifting weight is 407.9t, which is greater than 311t, thus meeting the lifting weight requirements.

[0063] S2. Construction of the upper tower column T1 section: The steel tower T1 section is divided into 4 pieces for on-site hoisting. The bottom T1 section and the pressure-bearing section are combined into 1 piece as the benchmark section for steel tower construction. It is constructed simultaneously with the steel-concrete composite section 39# tower column. The remaining T1-S, T1-H, and T1-M blocks will be constructed after the composite section is completed.

[0064] The construction sequence of the steel tower base section is as follows: installation of positioning brackets → hoisting of the bottom steel tower section → connection of reinforcing bars → pouring of concrete.

[0065] Furthermore, specifically, the positioning bracket installation involves using a bracket positioning method for the 3m steel shell at the bottom bearing section of the T1 segment of the upper tower column and the 3m high U-shaped groove of the bottom section. Eight brackets are arranged around the top ring plate of the joint section, and eight 75t three-way jacks are placed above the bracket beams to adjust the spatial position of the steel tower. For details on the bottom section steel tower positioning brackets, please refer to [link to details]. Figures 2-4 .

[0066] Furthermore, the hoisting of the base section steel tower specifically involves the hoisting of the T1 base section and the pressure-bearing section (reference section). After the three-way positioning device for the reference section is installed, debugged, inspected, and accepted, the reference section block is slowly lifted to the predetermined installation position. The hoisting of the T1 base section and the pressure-bearing section steel tower adopts an 8-point hoisting method to ensure balanced force on the block. Initial positioning is performed using wire ropes and guide chains, followed by precise positioning using three-way jacks.

[0067] Furthermore, the reinforcement connection and concrete pouring are as follows: the remaining standard sections of T1 section are installed. After the concrete pouring of the joint section is completed, the T1-S, T1-H, and T1-M blocks are hoisted. T1-H → T1-S / T1-M are hoisted in sequence. The sections are precisely positioned and welded, and the core reinforcement is tied. After acceptance, the core concrete is poured.

[0068] The T1 section of the steel tower is equipped with vertical alignment and matching parts. The middle block has 8 vertical matching parts and 12 lateral alignment parts, each side block has 4 vertical matching parts and 8 lateral alignment parts, and the side blocks and middle blocks inside the section have 8 longitudinal matching parts to ensure the vertical and longitudinal alignment accuracy requirements of the steel tower.

[0069] After the temporary positioning measures for the steel tower are completed, the vertical ribs are positioned using high-strength bolts. Twelve vertical ribs are designed for the edge blocks, and fifteen are designed for the core area. Each rib is connected using four M24 high-strength bolts at the top and bottom. After construction, these ribs are removed and reused for the next section. The positioning vertical ribs are then fully welded. The vertical rib arrangement is as follows: Figures 5-7 As shown.

[0070] S3. Installation of the upper tower column Tn+1 section of steel tower.

[0071] Furthermore, the installation of the upper tower column Tn+1 steel tower includes the hoisting and installation of steel tower sections T2 to T10.

[0072] Specifically, the steel tower sections T2 to T9 are divided into 3 or 4 pieces for hoisting. First, the core block is hoisted (positioning is done at night), and then the side and middle span steel tower sections are installed. The installation cycle is as follows: steel tower section hoisting → steel tower precise positioning, high-strength bolting, welding → core area reinforcement and concrete pouring → cyclic construction.

[0073] The lifting equipment for the T1 to T9 standard steel tower sections is specially designed, with a maximum lifting capacity of 311.11t (including the carrying steel bars) and a rated load capacity of 320t. The lifting equipment uses hydraulic jacks to adjust the lateral and longitudinal spacing of the lifting points via bolts. During the segmented lifting of the steel tower, the structural center of gravity is accurately calculated using a model, and then the lifting point arrangement is adjusted to ensure that the center of gravity coincides with the center of the hook, achieving stable lifting.

[0074] The preferred construction steps for hoisting and aligning standard sections of the steel tower are as follows:

[0075] Step 1: Calculate the center of gravity of the standard section of the steel tower and draw the relative position of the lifting lugs to the center of gravity. Adjust the lifting point position of the 320t lifting tool so that the main lifting point on the lifting tool coincides with the center of gravity of the steel tower section, the lower lifting point corresponds to the lifting lugs, and the lifting point is connected.

[0076] Step 2: The XGT15000-600S tower crane is used to lift the steel tower slowly by applying force in stages. After the tower is 10cm away from its original support surface, a special inspection is carried out on the levelness of the steel tower and the condition of the lifting equipment. After the inspection is passed, the lifting continues.

[0077] Step 3: Slowly raise the steel tower to a distance of about 1m from the top surface of the previous section, rotate the tower crane boom, adjust the lifting width, and hoist the steel tower to the design position directly above it, and then align it.

[0078] Step 4: When the distance between the bottom of the steel tower to be lifted and the installed steel tower in each direction differs by 1m, first guide the steel tower in the direction of lowering through two guide chains to make a rough positioning, and continue to slowly lower the steel tower.

[0079] Step 5: When the steel tower is about to be lowered to the design position, positioning adjustment is performed using multiple positioning adjustment mechanisms 1. Then, the vertical matching parts, lateral limiting parts, and positioning ribs installed on the steel tower are connected. First, the core block is positioned, preferably at night, followed by the side block positioning.

[0080] Reference Figures 8-13 As shown, the positioning adjustment mechanism 1 includes a first fixed connecting seat 101 and a second fixed connecting seat 102. The surfaces of the first fixed connecting seat 101 and the second fixed connecting seat 102 are respectively fixedly connected to the surface of the fixed steel tower segment and the surface of the hoisted and assembled steel tower segment.

[0081] The surfaces of the first fixed connecting seat 101 and the second fixed connecting seat 102 are both H-shaped. The inner walls of the first fixed connecting seat 101 and the second fixed connecting seat 102 are respectively fixedly connected to the first adapter seat 103 and the second adapter seat 104 by bolts. The inner walls of the first adapter seat 103 and the second adapter seat 104 are respectively rotatably connected to the support frame 105 and the tensioning hydraulic cylinder 106 by pins.

[0082] The tensioning hydraulic cylinder 106 includes a tensioning hydraulic rod 107, one end of which is rotatably connected to one end of the support frame 105 via a pin.

[0083] In use, the tensioning hydraulic rod 107 extends from or retracts into the tensioning hydraulic cylinder 106, and cooperates with the support frame 105 to drive the first adapter seat 103 and the second adapter seat 104 to move, which in turn drives the first fixed connecting seat 101 and the second fixed connecting seat 102 to move, thereby driving the hoisting and assembling steel tower segments to be positioned and assembled with the fixed steel tower segments that have already been fixed and installed.

[0084] The support frame 105 is rotatably connected to the tensioning hydraulic rod 107. Two symmetrically distributed fixed shafts 108 are fixedly connected to one end surface. The surfaces of the two fixed shafts 108 are slidably fitted with steering support columns 109. The surface of the steering support column 109 is provided with a locking groove 1010. The inner wall of the locking groove 1010 is fixedly connected with a locking tooth ring 1011.

[0085] A stop gear 1012 is fixedly sleeved on the surface of the fixed shaft 108, and the surface of the stop gear 1012 meshes with the inner wall of the locking gear ring 1011.

[0086] In use, the steering support column 109 is positioned and locked by the cooperation of the locking gear ring 1011 and the stop gear 1012.

[0087] One end of one of the fixed shafts 108 is fixedly connected to a support plate 1013. A pressure spring 1014 is sleeved on the surface of the fixed shaft 108. One end of each of the two pressure springs 1014 is fixedly connected to the surface of each of the two steering support columns 109. The other ends of each of the two pressure springs 1014 are fixedly connected to the surface of the support frame 105 and the surface of the support plate 1013, respectively.

[0088] In use, the pressure spring 1014 pushes and presses the rotating support column against the surface of the stop gear 1012, so that the inner wall of the locking gear ring 1011 on the rotating support column meshes with the surface of the stop gear 1012, thereby positioning and locking the rotating support column.

[0089] An auxiliary hydraulic cylinder 1015 is hinged to the surface of the steering support column 109. The auxiliary hydraulic cylinder 1015 includes an auxiliary hydraulic rod 1016. One end of the auxiliary hydraulic rod 1016 is hinged to a tensioning auxiliary block 1017. The surface of the tensioning auxiliary block 1017 is rotatably connected to the surfaces of the two steering support columns 109 through a rotating shaft.

[0090] The working principle of the positioning and adjustment mechanism 1 is as follows: when assembling and welding the steel tower segment, after hoisting the assembled steel tower segment to a certain distance above the fixed steel tower segment, the first adapter 103 and the second adapter 104 are fixedly connected to the first fixed connecting seat 101 and the second fixed connecting seat 102 respectively by bolts.

[0091] After the hoisted and assembled steel tower segment is initially positioned and made contact above the fixed steel tower segment, the hoisted and assembled steel tower segment is then pushed or tensioned based on the horizontal difference between the fixed steel tower segment and the hoisted and assembled steel tower segment.

[0092] When jacking the steel tower segment being hoisted and assembled, the steering support column 109 is moved to compress the pressure spring 1014, causing the locking gear ring 1011 on the steering support column 109 to separate from the stop gear 1012. Then, the steering support column 109 is rotated, causing the tensioning auxiliary block 1017 to approach the fixed steel tower segment. Then, the steering support column 109 is released, and under the force of the pressure spring 1014, the steering support column 109 resets, causing the locking gear ring 1011 to mesh with the stop gear 1012, thus locking the steering support column 109.

[0093] Then, by extending or retracting the auxiliary hydraulic rod 1016 inside the auxiliary hydraulic cylinder 1015, the surface of the tensioning auxiliary block 1017 is brought into contact with the surface of the fixed steel tower segment. Then, by extending the tensioning hydraulic rod 107 from the tensioning hydraulic cylinder 106, the surface of the tensioning auxiliary block 1017 is inserted and tightened with the surface of the fixed steel tower segment. Force is then applied to the hoisted and assembled steel tower segment, and the hoisted and assembled steel tower segment is pushed to adjust the weld alignment between the hoisted and assembled steel tower segment and the fixed steel tower segment.

[0094] When tensioning the steel tower segment being hoisted and assembled, the tensioning hydraulic rod 107 extends from the tensioning hydraulic cylinder 106. Then, by moving the steering support column 109, the pressure spring 1014 is compressed, causing the locking gear ring 1011 on the steering support column 109 to separate from the stop gear 1012. Then, the steering support column 109 is rotated, causing the tensioning auxiliary block 1017 to move closer to the surface of the steel tower segment being hoisted and assembled. The auxiliary hydraulic rod 1016 in the auxiliary hydraulic cylinder 1015 then extends or retracts, driving... The surface of the tensioning auxiliary block 1017 is inserted into the surface of the hoisting and assembly steel tower segment. Then, the tensioning hydraulic rod 107 is controlled to retract into the tensioning hydraulic cylinder 106. During the retraction of the tensioning hydraulic rod 107, it squeezes and pushes the tensioning auxiliary block 1017 to tighten the insertion of the hoisting and assembly steel tower segment. Then, under the force of the support frame 105, the tensioning hydraulic rod 107 retracts into the tensioning hydraulic cylinder 106 to apply force, driving the hoisting and assembly steel tower segment to be tensioned outward, and adjusting the weld seam alignment with the fixed steel tower segment.

[0095] Furthermore, during the welding alignment adjustment of the hoisted and assembled steel tower segments, the auxiliary hydraulic rod 1016 extends or retracts from the auxiliary hydraulic cylinder 1015 to ensure that the tensioning auxiliary block 1017 always maintains a horizontal fit with the surfaces of the hoisted and assembled steel tower segments and the fixed steel tower segments, thereby achieving better horizontal alignment during assembly.

[0096] By setting up the positioning and adjustment mechanism 1, during the assembly and welding of steel tower segments, the positioning and adjustment mechanism 1 pushes and tensions the hoisted and assembled steel tower segments, thereby achieving rapid horizontal adjustment and alignment of the hoisted and assembled steel tower segments and the fixed steel tower segments, thus reducing the difficulty of docking and achieving better welding results for steel tower construction.

[0097] The T10 segment weighs approximately 82.97 tons and is hoisted using high-strength ring slings and lifting lugs.

[0098] S4. On-site welding of steel towers.

[0099] Furthermore, on-site welding of the steel tower includes determining the welding work content, welding methods and selection of welding materials, bridge site welding and welding of the main welds.

[0100] Specifically, the welding work includes welding the fillet welds between the side block partition plates and the anchor web plates; welding the horizontal butt welds between the upper and lower tower section wall plates; welding the vertical butt welds between the side block and the core concrete block side wall plates; and welding the positioning vertical ribs and the patching sections.

[0101] Specifically, in the selection of welding methods and welding materials, the welding materials include welding rods of type E5015-G (φ4.0), solid welding wire of type G55A4UC1ZSN2 (φ1.2), and flux-cored welding wire of type T494T1-1C1AUH5.

[0102] Among them, welding rods are used for tack welding and repair, solid welding wires are used for transverse butt welds (root pass welding) of wall panels and anchor webs, flux-cored welding is used for transverse butt welds (filling and cover welding) of wall panels and anchor webs; and vertical butt welds between side wall panels.

[0103] Specifically, the bridge site welding follows the following sequence: fillet weld between the side blocks, core concrete blocks, and pressure-bearing slabs of the T1 tower section: fillet weld between the steel tower partition and the anchor web plate → horizontal butt weld between the upper and lower block walls and the anchor web plate → vertical butt weld between the side blocks and the core concrete block side walls → butt weld of the positioning vertical ribs and the patch section.

[0104] The standard tower section bridge site welding sequence is as follows: welding the horizontal butt weld between the upper and lower tower section wall panels → welding the vertical butt weld between the side block and the core concrete block side wall panels → welding the horizontal butt weld between the upper and lower tower section wall panels and anchor webs → welding the positioning vertical ribs and the patching section, etc.

[0105] Specifically, the main welds include transverse butt welds between steel tower segments, longitudinal butt welds between side blocks and core concrete block panels, and patch welds.

[0106] The transverse butt welds between steel tower segments, with reinforcing bars inside the core concrete blocks, create a complex structure lacking sufficient space for welding. The butt welds of the wall panels employ a single-sided welding with double-sided forming process, using constraint fixtures to control welding deformation at the circumferential joints. The butt welds of the side block wall panels utilize an asymmetrical K-groove. To control welding deformation, half of the outer weld is first filled, then the root is cleaned and the inner weld is filled, followed by welding the outer weld. Welding is then performed alternately on both sides. Welding deformation is monitored throughout the welding process, and the welding sequence is adjusted promptly to control the verticality of the tower columns.

[0107] The longitudinal butt welds between the side panels and the core concrete block wall panels are constructed by dividing each steel tower segment longitudinally into three blocks, which are then transported to the bridge site and welded together to form a complete segment. The longitudinal butt welds of the wall panels employ a single-sided welding with double-sided forming process. For wall panels thicker than 40mm, the bevel is designed as an "X" shape, with symmetrical welding on both sides to reduce post-weld deformation. For wall panels thinner than 40mm, the bevel is designed as a "V" shape. A guide plate is used to control localized welding deformation, avoiding welding in the confined space inside the tower, ensuring welding quality, and improving bridge site work efficiency. The guide plate is removed after the root pass weld is completed. The appearance of the welds on the outer side of the steel tower directly affects its aesthetic effect. The butt welds of the wall panels are performed using a trackless crawling welding robot, significantly improving the weld appearance.

[0108] For the patch section weld, during assembly, the excess height of the butt weld should be ground flat to ensure assembly accuracy. Flame cutting or grinding to create weld clearance holes in the patch section is strictly prohibited. The patch section is welded using CO2 gas shielded welding. The fillet welds of the patch section are welded first, followed by the butt welds.

[0109] S5. Steel tower surface coating.

[0110] The coating of the outer surface of the steel tower structure shall be carried out in accordance with the 7th system of the "Technical Conditions for the Supply of Protective Coatings and Paints for Railway Steel Bridges" (Q / CR 730-2019); the coating of the core concrete interior shall be carried out in accordance with the 4th system of the Ministry of Railways standard "Technical Conditions for the Supply of Protective Coatings and Paints for Railway Steel Bridges" (Q / CR 730-2019).

[0111] S6. Reinforcement construction in the core area.

[0112] To reduce on-site installation work, the steel reinforcement inside the steel tower is installed at the Baoqiao Steel Tower Manufacturing Plant as much as possible. When installing the reinforcement, factors such as the welding space for the steel tower sections, the compression space for the vertical main reinforcement, and the concrete pouring boundary lines are comprehensively considered. BIM simulation is used to model the construction sequence of the reinforcement, core steel structure, shear studs, and cable guides, optimizing the reinforcement installation sequence, allowing for early modification of conflicting reinforcement, and reducing rework.

[0113] Vertical main reinforcement bars of φ25mm and φ32mm are connected by tapered sleeve joints; horizontal main reinforcement bars of φ36mm are connected by straight threaded sleeves; horizontal stirrups with a diameter of 20mm are connected by single-sided welding with a welding length ≥10d. The quality requirements for reinforcement connection and binding construction meet the "Standard for Acceptance of Construction Quality of High-Speed ​​Railway Bridge and Culvert Engineering" (TB10752-2018).

[0114] S7. Core Area Concrete Construction

[0115] This project utilizes C60 high-strength, non-shrink concrete. By selecting superior concrete raw materials and optimizing the concrete mix proportions, a high-strength concrete mix design method based on organic-inorganic composite viscosity-reducing technology was developed. This method effectively reduces the amount of cementitious materials used in the concrete, increases the thickness of the water film layer, achieves viscosity reduction and enhancement, and establishes key technologies for improving the pumpability of high-strength concrete. Simultaneously, full-scale and scaled-down model tests were conducted to determine the concrete performance indicators.

[0116] The concrete for the upper tower column is produced and supplied by a concrete mixing plant. Two pump pipes are installed, and the concrete is pumped to the upper tower column by an HBT9050CH-5S high-pressure ground pump. The concrete pouring is carried out using a 13m fixed full-rotation placing boom, with the placing boom and its support fixed to the top of the steel tower segment.

[0117] The temporary support frame (105) is a steel bracket, which is bolted to the steel tower. The temporary support frame is equipped with a vertical connection system. The temporary support frame is processed in the steel structure workshop of the project department. After processing, it is transported to the steel tower workshop for installation, and is transported and hoisted together with the steel tower sections.

[0118] After the steel tower welding and rebar tying are completed, the core concrete is poured. The concrete is laid out in layers from the center outwards. A B50 vibratory pump is used for compaction. Vibration personnel work on scaffolding platforms erected above the reinforcing bars, penetrating deep into the concrete surface to ensure quality compaction. Personnel must go down into the area below the inner partition to perform vibration.

[0119] S8. Intelligent Construction of Steel Towers

[0120] Tower crane structural health monitoring system. Vibration, stress, and tilt sensors are installed on the tower crane's body, attachments, jib, counterweight jib, slewing tower, and hook to monitor the stress and deformation of key structures in real time. Using BIM-FEM technology, combined with external load data under different working conditions, finite element mechanical simulation calculations are performed to assess the tower crane's structural health status in real time and issue early warnings. The system also links with the tower crane control system and operator to predict risks and promptly activate emergency plans.

[0121] Auxiliary hoisting system. A high-performance controller is installed inside the large tower crane to monitor key operating parameters such as hook position and lifting weight in real time. This data is then fitted to target position data and calculated in 3D and 2D simulation pages. A self-developed intelligent control algorithm is built-in to automatically generate the optimal hoisting path and operating instructions, providing multi-dimensional and high-precision guidance for the tower crane operator to ensure accurate construction of heavy lifting loads.

[0122] Tower crane digital twin system. This system establishes a BIM model of the tower crane and 3D models of various operating scenarios, integrating relevant data from the tower crane monitoring system, intelligent hoisting auxiliary control system, and structural health monitoring system for dynamic visualization. This provides an integrated management and control digital twin platform for the operation and maintenance supervision of large tower cranes. Simultaneously, the accumulated operational and safety monitoring data provide data support for research and optimization upgrades of ultra-large tower cranes.

[0123] By setting steps one through five, the steel box is pre-processed into sections during the construction of the steel box core concrete composite cable tower, and then the sections are hoisted and installed in stages. This reduces the lifting weight of the steel structure. Furthermore, the positioning and adjustment mechanism 1 precisely aligns the hoisted and assembled steel tower sections with the fixed steel tower sections that have already been installed and positioned. This solves the problems of heavy steel structure lifting and high docking difficulty in the existing construction of steel box core concrete composite cable towers, which affect the quality of welds in the steel tower construction.

[0124] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A construction method for a steel-box core concrete composite cable tower, characterized in that, Includes the following steps: Step 1: Install the segment positioning bracket; Step 2: Installation of reinforcing steel bars in the connecting section; Step 3: Hoisting and positioning the steel tower reference section; Step 4: Concrete pouring for the joint section; Step 5: Construction of the upper steel tower; The construction of the upper steel tower specifically includes the following steps: S1. The steel tower column is divided into ten segments, T1 to T10, based on its height. Considering the on-site hoisting and welding conditions, the steel tower column is divided into 33 sections for hoisting. The maximum hoisting weight is 311t. When the XGT15000-600S tower crane has a lifting width of 35m, the lifting height is 298m, and the lifting weight is 407.9t, which is greater than 311t, thus meeting the lifting weight requirements. S2. Construction of the upper tower column T1 section: The steel tower T1 section is divided into 4 pieces for on-site hoisting. The bottom T1 section and the pressure-bearing section are combined into 1 piece as the benchmark section for steel tower construction. It is constructed simultaneously with the steel-concrete composite section 39# tower column. The remaining T1-S, T1-H, and T1-M blocks will be constructed after the composite section is completed. S3. Installation of the upper tower column Tn+1 section steel tower, which includes the hoisting and construction of steel tower sections T2 to T10; Specifically, the installation of each section of the steel tower from T2 to T9 is carried out in three or four pieces. First, the core block is hoisted, and then the side and middle span steel tower sections are installed. The installation cycle is as follows: steel tower section hoisting → steel tower precise positioning, high bolting, and welding → core area reinforcement and concrete pouring → cyclic construction. The lifting equipment for the T1 to T9 standard steel tower sections is specially designed, with a maximum lifting weight of 311.11t and a rated load capacity of 320t. The lifting equipment is adjusted laterally via the hydraulic jack and longitudinally via the screw rods to adjust the lateral and longitudinal spacing of the lifting points. When lifting the steel tower sections, the structural center of gravity is accurately calculated using a model, and then the arrangement of the lifting points is adjusted to make the center of gravity coincide with the center of the hook, thus achieving stable lifting. The construction steps for hoisting and aligning standard sections of the steel tower are as follows: Step 1: Calculate the center of gravity of the standard section of the steel tower and draw the relative position of the lifting lugs to the center of gravity. Adjust the lifting point position of the 320t lifting tool so that the main lifting point on the lifting tool coincides with the center of gravity of the steel tower section, the lower lifting point corresponds to the lifting lugs, and the lifting point is connected. Step 2: The XGT15000-600S tower crane is used to lift the steel tower slowly by graded loads. After the tower is 10cm away from its original support surface, a special inspection is carried out on the levelness of the steel tower and the condition of the lifting equipment. After the inspection is passed, the lifting continues. Step 3: Slowly raise the steel tower to a distance of 1m from the top surface of the previous section, rotate the tower crane boom, adjust the lifting width, and hoist the steel tower to the design position directly above it, and then align it. Step 4: When the distance between the bottom of the steel tower to be lifted and the already installed steel tower differs by 1m in each direction, first guide the steel tower to lower in the correct direction using two guide chains for rough positioning, and then continue to lower the steel tower slowly. Step 5: When the steel tower is about to be lowered to the design position, the positioning is adjusted by multiple positioning adjustment mechanisms (1), and then the core block is positioned by connecting the vertical matching parts, lateral limiting parts and positioning vertical ribs set on the steel tower. The positioning is carried out at night, and then the side blocks are positioned. The T10 segment was hoisted using high-strength ring slings and lifting lugs. S4. On-site welding of steel towers, including determining the welding work content, welding methods and selection of welding materials, bridge site welding and welding of main welds; S5. Steel tower surface coating; S6. Reinforcement construction in the core area; S7. Concrete construction in the core area; S8. Intelligent Construction of Steel Towers; The positioning adjustment mechanism (1) includes a first fixed connecting seat (101) and a second fixed connecting seat (102). The surfaces of the first fixed connecting seat (101) and the second fixed connecting seat (102) are fixedly connected to the surfaces of the fixed steel tower segment and the hoisting and assembling steel tower segment, respectively. The surfaces of the first fixed connecting seat (101) and the second fixed connecting seat (102) are both H-shaped. The inner walls of the first fixed connecting seat (101) and the second fixed connecting seat (102) are fixedly connected to the first adapter seat (103) and the second adapter seat (104) by bolts, respectively. The inner walls of the first adapter seat (103) and the second adapter seat (104) are rotatably connected to the support frame (105) and the tensioning hydraulic cylinder (106) by pins, respectively. The tensioning hydraulic cylinder (106) includes a tensioning hydraulic rod (107). One end of the tensioning hydraulic rod (107) is rotatably connected to one end of the support frame (105) by pins.

2. The construction method for a steel-box core concrete composite cable tower according to claim 1, characterized in that: The welding materials used in the on-site welding of the steel tower include welding rods of type E5015-G (φ4.0), solid welding wire of type G55A4UC1ZSN2 (φ1.2), and flux-cored welding wire of type T494T1-1C1AUH5.

3. The construction method for a steel-box core concrete composite cable tower according to claim 1, characterized in that: Two symmetrically distributed fixed shafts (108) are fixedly connected to one end of the support frame (105) and the tensioning hydraulic rod (107). A steering support column (109) is slidably sleeved on the surface of the two fixed shafts (108). A locking groove (1010) is opened on the surface of the steering support column (109). A locking tooth ring (1011) is fixedly connected to the inner wall of the locking groove (1010).

4. The construction method for a steel-box core concrete composite cable tower according to claim 3, characterized in that: A stop gear (1012) is fixedly sleeved on the surface of the fixed shaft (108), and the surface of the stop gear (1012) meshes with the inner wall of the locking gear ring (1011).

5. The construction method for a steel-box core concrete composite cable tower according to claim 4, characterized in that: One end of one of the fixed shafts (108) is fixedly connected to a support plate (1013), and a pressure spring (1014) is sleeved on the surface of the fixed shaft (108). One end of each of the two pressure springs (1014) is fixedly connected to the surface of the two steering support columns (109), and the other end of each of the two pressure springs (1014) is fixedly connected to the surface of the support frame (105) and the surface of the support plate (1013), respectively.

6. The construction method for a steel-box core concrete composite cable tower according to claim 5, characterized in that: An auxiliary hydraulic cylinder (1015) is hinged to the surface of the steering support column (109). The auxiliary hydraulic cylinder (1015) includes an auxiliary hydraulic rod (1016). One end of the auxiliary hydraulic rod (1016) is hinged to a tensioning auxiliary block (1017). The surface of the tensioning auxiliary block (1017) is rotatably connected to the surfaces of the two steering support columns (109) through a rotating shaft.

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