A construction method for installing arch ribs of a long-span upper-bearing arch bridge

Abstract

This invention discloses a method for installing the arch ribs of a long-span, upper-bearing arch bridge. It outlines a rapid construction method for the arch ribs of a prefabricated CFST arch bridge, including: establishing a finite element model on a computer according to the bridge's design dimensions; calculating the stress-free length or stress-free curvature data of each component; fabricating components based on this data; determining high-altitude positioning data; and using digital pre-assembly technology to automatically analyze the target coordinates of three-dimensional attitude fine-tuning control points and adjust the three-dimensional attitude. All components are transported to the construction site for installation and positioning, with corrections made during the positioning of the arch rib segments to be installed. Installation parameters are controlled to ensure continuous and precise installation of the arch rib segments until the arch rib is closed. This invention achieves rapid cantilever construction of the arch ribs through rational organization and key technology control, reducing the time spent in the large cantilever state and effectively mitigating the risks associated with large cantilever assembly.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology, specifically relating to a method for installing the arch ribs of a long-span, upper-bearing arch bridge. Background Technology

[0002] Currently, the types of arch bridges being constructed include stone arch bridges, steel-concrete composite arch bridges, steel arch bridges, and concrete arch bridges. Among long-span arch bridges, steel-concrete composite bridges are widely used due to their unique advantages. Steel-concrete composite (CFST) is a composite material formed by filling a steel tube with concrete. The principle of its composite design is as follows: the concrete is subjected to the constricting effect of the steel tube wall, which greatly improves its load-bearing capacity, strength, and toughness; the concrete filling the steel tube inhibits the local buckling of the steel tube, improves the stability of the structure, and reduces the amount of steel used; the overall cost-effectiveness of the composite material is significantly better than that of the materials themselves.

[0003] A deck arch bridge is a type of bridge where the bridge deck is set on the main load-bearing structure (i.e., the arch rib) of the bridge span. The arch abutment is a component that transfers the thrust of the arch rib end (also called the arch end) to the bedrock. It is located at the connection between the arch bridge and the bedrock at both ends. Both ends of the arch rib of a deck arch bridge are supported on the arch abutment. The arch abutment is an important component that supports the superstructure of the arch. Due to the large span of the arch rib and the influence of geographical location and transportation conditions, in order to ensure the construction period and economic efficiency, the prefabricated CFST arch bridge arch rib is usually manufactured in the factory and then transported to the construction site for hoisting and installation. Due to transportation limitations, the arch rib needs to be disassembled into several sections for segmental installation.

[0004] In actual construction, only necessary installation procedures are carried out on-site. While ensuring accuracy and quality, it is also necessary to improve the efficiency of on-site cantilever construction. However, the greatest safety risk in arch bridge construction occurs during the cantilever assembly stage of the arch rib. As the span increases, the safety risk tends to increase. How to achieve rapid and high-precision installation of the arch rib and reduce the risks of large cantilever assembly is an urgent problem to be solved in the installation of arch ribs for arch bridges. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned technical problems and provide a rapid construction method for the arch ribs of prefabricated CFST arch bridges. The technical solution adopted to achieve the purpose of this invention is as follows:

[0006] A method for installing the arch ribs of a long-span, upper-bearing arch bridge, comprising the following steps:

[0007] (1) Establish a finite element model on the computer according to the design dimensions of the arch bridge, and calculate the stress-free length or stress-free curvature data of each component;

[0008] (2) The factory processes the components according to the data in step (1) to obtain the actual processing model of the components. Through the actual processing model and theoretical deformation calculation, the high-altitude positioning data is determined.

[0009] (3) The component is initially positioned by hoisting and three-dimensional scanning is performed to obtain the actual three-dimensional posture. Digital pre-assembly technology is used to automatically analyze the target coordinates of the three-dimensional posture fine-tuning control points, and a fully automatic scanning robot is used to monitor and dynamically adjust the three-dimensional posture in real time.

[0010] (4) Transport all components to the construction site for installation and positioning, introduce measurement robots and automated monitoring technology, observe the temperature linear change law of the installed arch rib segments, conduct big data statistical analysis, obtain the corresponding functions and related parameters, and make corrections when positioning the arch rib segments to be installed.

[0011] (5) The arch rib segment is pulled by a single cable to prevent the steel strands from getting tangled and twisted, maintain the shape of the arch rib segment, control the unbalanced force of the cable and the deflection of the cable tower, and ensure the safety of the structure.

[0012] (6) Control the uniformity of the back cable force, control the balanced tension, control the tower deviation, control the arch rib alignment, and install the wind bracing synchronously. Control the continuous and precise installation of the arch rib segments until the arch rib is closed.

[0013] Preferably, in step (1), based on the theory of the stress-free state method, under the determined load and boundary conditions, the stress-free length of the component is consistent with that of its stress-free state, and the completed bridge state is consistent with the target state. According to the construction steps of the bridge, a finite element model is established to calculate the stress-free length or stress-free curvature of the component.

[0014] Preferably, in step (2), the factory processes the components according to the data. After the components are processed, the actual processing model of the components is obtained. The high-altitude positioning data is determined by the actual processing model and theoretical deformation calculation. When positioning the components on site, the manufacturing and processing state is restored, thereby achieving precise high-altitude docking of the arch ribs.

[0015] Preferably, a mathematical connection equation is established between the cable force before the steel pipe arch bridge is closed and the arch rib shape and stress after the cable is removed and the bridge is formed. An optimal mathematical model for the entire process with coupled multi-boundary constraints is established. A program for calculating the optimal single tension cable force for the entire process is developed.

[0016] Preferably, in step (3), the three-dimensional scanning model of the prototype reset control theory is used as the target to perform a three-dimensional scan of the initial positioning posture of the hoisting to obtain the actual three-dimensional posture. The target coordinates of the three-dimensional posture fine-tuning control point are automatically analyzed by digital pre-assembly technology, and the three-dimensional posture is dynamically adjusted in real time by a fully automatic scanning robot, thereby improving the three-dimensional accuracy of the arch rib installation.

[0017] Preferably, in step (4), the factors affecting the installation and positioning of the arch rib include temperature and wind speed, which are coupled together, and are also influenced by the interrelationship of the back rib, the offset of the gantry, and the deformation of the arch rib.

[0018] The installation and positioning of the arch rib are affected by a combination of factors, including temperature and wind speed, and are also influenced by the interrelationship between the backstay cable, the offset of the anchor tower, and the deformation of the arch rib. The influence becomes more pronounced with increasing cantilever length. To overcome these adverse effects, a measurement robot and automated monitoring technology are introduced. By observing the linear temperature changes of the installed segments and performing big data statistical analysis, corresponding functions and related parameters are obtained. These parameters are then corrected during the positioning of the segments to be installed, achieving accurate positioning in complex environments.

[0019] Preferably, in step (5), the back strap is pulled by a single strand to prevent the steel strands from getting tangled and twisted; the automatic continuous pretensioning device is used to ensure that the pretension force of a single cylinder is equal by using the principle that the internal pressure of the communicating vessel is the same.

[0020] Preferably, in step (6), the balancing tension is carried out according to the program by integrating and controlling multiple jacks.

[0021] Preferably, it includes at least four jacks.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) This invention focuses on taking measures in terms of steel structure processing, cable hoisting system, inclined cable fastening system, and unfavorable construction environment. Through reasonable organization and key technology control, it aims to achieve rapid construction of arch rib cantilever and reduce the time of large cantilever state, so as to effectively reduce the risk of large cantilever assembly.

[0024] (2) This invention solves the problem of high-precision control of large-scale prefabricated bolted bridges through a prototype reset installation control method; proposes a stress-free arch formation calculation method for large-span arch bridges based on precise control of core stress-free parameters; and establishes a full-process optimal mathematical model that can couple constraints throughout the entire construction process. This enables precise high-altitude alignment of the arch ribs, synchronous installation of wind braces, and reduces the risk of large cantilevered single-limb arch ribs.

[0025] (3) This invention improves the processing accuracy of steel structures through three-dimensional laser scanning digital pre-assembly technology, simulates the feasibility of the structure to be installed in advance, and uses three-dimensional posture fine-tuning technology for the installation of large segments of bolted arch bridges to comprehensively improve installation accuracy. It also studies multi-factor coupled environments and arch rib rapid and accurate positioning technology. By introducing measurement robots and automated monitoring technology, it grasps the law of arch rib linear change and achieves rapid positioning of the arch ribs.

[0026] (4) Through the automatic continuous pre-tensioning intelligent tensioning equipment, the automatic continuous pre-tensioning and overall tensioning of multiple strands can be realized simultaneously by a control center, which greatly improves the pre-tensioning efficiency, the cable force accuracy and synchronization control are high, the maximum tension error is controlled within 2%, ensuring that each steel strand is subjected to uniform force, reducing structural safety risks and shortening the construction period. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the back cable installation of the present invention. Figure 1 .

[0028] Figure 2 This is a schematic diagram of the back cable installation of the present invention. Figure 2 .

[0029] Figure 3 This is a schematic diagram of the traction system of the present invention. Figure 1 .

[0030] Figure 4 This is a schematic diagram of the traction system of the present invention. Figure 2 .

[0031] Figure 5 This invention relates to a layout diagram for installing a pull hoist with a wind brace. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the invention, and these aspects of the invention can be implemented even without these specific details.

[0033] A method for installing the arch ribs of a long-span, upper-bearing arch bridge, comprising the following steps:

[0034] (1) Establish a finite element model on the computer according to the design dimensions of the arch bridge, and calculate the stress-free length or stress-free curvature data of each component;

[0035] (2) The factory processes the components according to the data in step (1) to obtain the actual processing model of the components. Through the actual processing model and theoretical deformation calculation, the high-altitude positioning data is determined.

[0036] (3) The component is initially positioned by hoisting and three-dimensional scanning is performed to obtain the actual three-dimensional posture. Digital pre-assembly technology is used to automatically analyze the target coordinates of the three-dimensional posture fine-tuning control points, and a fully automatic scanning robot is used to monitor and dynamically adjust the three-dimensional posture in real time.

[0037] (4) Transport all components to the construction site for installation and positioning, introduce measurement robots and automated monitoring technology, observe the temperature linear change law of the installed arch rib segments, conduct big data statistical analysis, obtain the corresponding functions and related parameters, and make corrections when positioning the arch rib segments to be installed.

[0038] (5) The arch rib segment is pulled by a single cable to prevent the steel strands from getting tangled and twisted, maintain the shape of the arch rib segment, control the unbalanced force of the cable and the deflection of the cable tower, and ensure the safety of the structure.

[0039] (6) Control the uniformity of the back cable force, control the balanced tension, control the tower deviation, control the arch rib alignment, and install the wind bracing synchronously. Control the continuous and precise installation of the arch rib segments until the arch rib is closed.

[0040] Preferably, in step (1), based on the theory of the stress-free state method, under the determined load and boundary conditions, the stress-free length of the component is consistent with that of its stress-free state, and the completed bridge state is consistent with the target state. According to the construction steps of the bridge, a finite element model is established to calculate the stress-free length or stress-free curvature of the component.

[0041] Preferably, in step (2), the factory processes the components according to the data. After the components are processed, the actual processing model of the components is obtained. The high-altitude positioning data is determined by the actual processing model and theoretical deformation calculation. When positioning the components on site, the manufacturing and processing state is restored, thereby achieving precise high-altitude docking of the arch ribs.

[0042] Preferably, a mathematical connection equation is established between the cable force before the steel pipe arch bridge is closed and the arch rib shape and stress after the cable is removed and the bridge is formed. An optimal mathematical model for the entire process with coupled multi-boundary constraints is established. A program for calculating the optimal single tension cable force for the entire process is developed.

[0043] Preferably, in step (3), the three-dimensional scanning model of the prototype reset control theory is used as the target to perform a three-dimensional scan of the initial positioning posture of the hoisting to obtain the actual three-dimensional posture. The target coordinates of the three-dimensional posture fine-tuning control point are automatically analyzed by digital pre-assembly technology, and the three-dimensional posture is dynamically adjusted in real time by a fully automatic scanning robot, thereby improving the three-dimensional accuracy of the arch rib installation.

[0044] Preferably, in step (4), the factors affecting the installation and positioning of the arch rib include temperature and wind speed, which are coupled together, and are also influenced by the interrelationship of the back rib, the offset of the gantry, and the deformation of the arch rib.

[0045] The installation and positioning of the arch rib are affected by a combination of factors, including temperature and wind speed, and are also influenced by the interrelationship between the backstay cable, the offset of the anchor tower, and the deformation of the arch rib. The influence becomes more pronounced with increasing cantilever length. To overcome these adverse effects, a measurement robot and automated monitoring technology are introduced. By observing the linear temperature changes of the installed segments and performing big data statistical analysis, corresponding functions and related parameters are obtained. These parameters are then corrected during the positioning of the segments to be installed, achieving accurate positioning in complex environments.

[0046] Preferably, in step (5), the back strap is pulled by a single strand to prevent the steel strands from getting tangled and twisted; the automatic continuous pretensioning device is used to ensure that the pretension force of a single cylinder is equal by using the principle that the internal pressure of the communicating vessel is the same.

[0047] Preferably, in step (6), the balancing tension is carried out according to the program by integrating and controlling multiple jacks.

[0048] Preferably, it includes at least four jacks.

[0049] Example 1

[0050] Taking the arch rib installation construction method of the Wujiang Grand Arch Bridge as an example:

[0051] (1) Establish a finite element model on the computer according to the design dimensions of the arch bridge, and calculate the stress-free length or stress-free curvature data of each component;

[0052] (2) The factory processes the components according to the data in step (1) to obtain the actual processing model of the components. Through the actual processing model and theoretical deformation calculation, the high-altitude positioning data is determined.

[0053] (3) The component is initially positioned by hoisting and three-dimensional scanning is performed to obtain the actual three-dimensional posture. Digital pre-assembly technology is used to automatically analyze the target coordinates of the three-dimensional posture fine-tuning control points, and a fully automatic scanning robot is used to monitor and dynamically adjust the three-dimensional posture in real time.

[0054] (4) Arch rib hoisting

[0055] After the arch rib is transported to the bridge site area, it is adjusted to the position of the main crane projection axis to facilitate the lifting of the arch rib and prevent the component from rotating significantly during lifting.

[0056] When the segments are hoisted into the air, the hoisting points on the arch foot side are adjusted to be at the lower end and the hoisting points on the arch top side are at the higher end, so that the inclination angle of the arch ribs roughly conforms to the posture of the completed bridge.

[0057] After the arch rib is adjusted to the correct position, it is slowly moved closer to the flange interface. The worker uses a hand-operated hoist to pull the arch rib closer to the interface. The flange position is then finely adjusted using tools such as cable cranes and hand-operated hoists. When aligning the flange, it is essential to ensure that the high bolts and punch pins can pass freely and that the flange is tightly fitted on one side.

[0058] After adjustment, drive punch pins and temporary connecting bolts into the segment connection flange for centering and positioning adjustment;

[0059] After aligning the bolt holes, quickly install the flange bolts and tighten them symmetrically.

[0060] (5) Back-cable traction construction

[0061] Considering the large workload of the back-cable cable due to its spatial nature, pre-threading is generally adopted to improve the efficiency of arch rib installation. Back-cable traction typically proceeds from low to high. First, the steel strands are temporarily connected to the traction device, then secured to the traction wire rope using rope clamps, with appropriate counterweights (usually 100-200 kg) added below to facilitate personnel access to the steel strands for threading into the anchorages. Finally, the winch is slowly started for traction. During traction, proper spatial arrangement of the steel strands is maintained to prevent tangling. After back-cable traction is completed, a P-anchor is promptly installed at the rear anchor end, and the tensioning end is secured with anchorages. Tightening is strictly prohibited to prevent excessive displacement of the anchor tower. When traction is performed on the perforated pier, the pre-embedded hole locations are ground beforehand to prevent scratching the steel strands (see...). Figure 1-2 ).

[0062] (6) Cable Traction Construction

[0063] Similar to the backstay traction system, the steering wheel of the cable traction system gradually moves forward as the arch rib segments are assembled. During cable traction, the steel strands are temporarily fixed using the same method as the backstay traction system. A winch pulls the steel strands to the segment to be installed and uses temporary anchors to fix them to the arch rib. A 15-20m extension is left at the front end of the temporary anchor (the exact length depends on the anchor point location of the segment), and the cable is temporarily fixed to the previous segment. After the arch rib segment is in place, the steel strands are manually threaded into the anchor box and fixed with P-anchors. A cable tension sensor is installed in front of the P-anchor for monitoring the steel strand tension (see...). Figure 3-4 ).

[0064] (7) Tighten the back straps evenly.

[0065] After the high bolts of the arch rib chord flange are tightened, the pre-tightening of the back tension cable begins. First, install the jack fixing bracket on the junction pier. Use a tower crane or winch in conjunction with manual pulling to install the jack to the tensioning end of the back tension cable. After installation, ensure that the extension and retraction direction of the hydraulic cylinder is consistent with the tensioning direction. Then connect the hydraulic pipe, start the pre-tightening jack, input the jack calibration parameters into the back-end system, and check whether the tensioning hydraulic pump and the jack are compatible.

[0066] First, the steel strands of the cable backing cable are tightened. After the sag is reduced, pre-stressing is applied. Due to the significant sag of the cable backing cable, an overall tensioning jack can be used for overall tightening while the pre-tightening jack is in place to improve efficiency. Once the sag of the cable backing cable is reduced, pre-tightening is performed using a pre-tightening jack, with a single pre-tightening force set at 20kN. After pre-tightening, the data from the cable force sensor and jacks are checked. The pre-tightening of the cable backing cable is considered complete when the cable force reaches 20kN and the difference in tension between each steel strand is less than 2%. During the pre-tightening process, it is necessary to monitor the displacement of the cable tower, the alignment of the main arch rib, and the lifting cable force of the cable hoisting system, and determine whether the data changes meet the requirements.

[0067] (8) Balanced tensioning of back cable

[0068] The back-cable tensioning process consists of three steps: first, the back-cable system is converted to a cable-stayed system; then, the back-cable tensioning is performed; and finally, the arch rib is finely adjusted.

[0069] Step 1: After pre-tensioning, the weight of the arch rib segment is still mainly borne by the cable, requiring a switch to the cable-stayed system. The force conversion is generally performed in three stages. After pre-tensioning, the axial deviation and elevation of the arch rib nodes are re-measured. Once the data meets the requirements, the tension is set to 50% of the monitoring cable force for synchronous tensioning. The four jacks of the back-stayed cable are simultaneously activated, automatically extending the cylinders and retracting the oil. After reaching the tension, pressure is maintained. Considering the longer back-stayed cable, the pressure maintenance time is generally set to 180-300 seconds. The longer the back-stayed cable, the longer the pressure maintenance time can be appropriately increased. After pressure maintenance, the cable crane is operated to appropriately reduce the lifting cable force proportionally. Then, the data on the arch rib, tower deflection, and cable force are re-measured. After confirming the data is correct, 70% and 80% cable tensioning is performed according to the above steps. After tensioning to 80%, the cable crane is withdrawn from operation. During the staged tensioning system conversion process, the arch rib elevation and tower deflection need to be dynamically measured.

[0070] Step Two: After the system conversion is completed, the adjustment of the arch rib elevation and alignment is entirely handled by the fastening system. Based on the actual site temperature and the alignment variation pattern, subsequent tensioning and positioning are carried out. During tensioning, the focus is on controlling the arch rib elevation and the offset of the fastening tower. Subsequent tensioning is performed synchronously at 85%, 90%, and 95% levels, stopping once the initial positioning elevation is reached. The arch rib elevation tensioning follows the principle of "better lower than higher," and can be 0.5–1 cm lower than the monitoring elevation. The back-cable fasteners adhere to the principle of "better to pull than to release," as releasing the cables in a cantilevered state carries significant risk.

[0071] Step 3: After initial positioning, monitor the arch rib alignment and buckle misalignment. After the nighttime temperature drops to the standard temperature or stabilizes, observe whether the arch rib alignment meets the requirements. If the elevation is too low, fine-tune the arch rib positioning between 5-7 AM. Throughout the entire back-cable tensioning process, assign a dedicated person to inspect the tensioned steel strands, focusing on the opening and closing of the clamps, checking for slippage or breakage, and ensuring consistent elongation of each strand. After fine-tuning, remove the tensioning equipment and tighten the anti-loosening anchor plate, ensuring the bolts are firmly against the steel strand clamps to prevent them from loosening. To further ensure back-cable safety, install a bracket and limiting plate at the tensioning head position and apply P-anchors to prevent steel strand slippage.

[0072] The arch ribs, backstays, and towers are significantly affected by the overall temperature difference and temperature gradient. While the overall temperature difference can be corrected through theoretical calculations, the influence of the temperature gradient is difficult to simulate. Therefore, it is necessary to observe the arch rib alignment and temperature in advance to understand their changing patterns. As the temperature decreases, the arch rib elevation will rise, while the backstay steel strands will cause the arch rib elevation to decrease due to the relaxation effect. Therefore, alignment observations must be conducted at night to determine the data for fine-tuning, and fine-tuning should be carried out in the early morning.

[0073] (9) Wind brace installation

[0074] Before installing the wind bracing, remeasure the absolute position and relative deviation of the left and right sides, and strictly control the height difference between the left and right sides.

[0075] After the left and right arch ribs are installed, the wind braces are hoisted. The inclination angle of the wind braces is adjusted on the site in advance to be basically consistent with the installation inclination angle. The wind braces are hoisted to the front end of the installation position and pulled by hand chain hoists so that their ends are embedded into the node plates. The tension and slack of each hand chain hoist are adjusted according to the mutual misalignment. Since the problem of mutual matching of the wind braces in the stress-free state has been solved in the vertical assembly stage, only a small flexibility deformation is required to gradually align the node plates and connecting plates. Then, the drift pins are driven in and the temporary bolts are tightened to achieve precise alignment of the wind braces.

[0076] Tighten the high-strength bolts on the wind brace node plate according to the high-strength bolt technical specifications to complete the installation of the wind brace. (See...) Figure 5 )

[0077] (10) Butt sleeve welding

[0078] After the wind bracing is installed, the connecting sleeves between the arch rib segments are installed. To facilitate the installation, the sleeves can be divided into 2 to 3 equal parts, with bevels on all sides.

[0079] The actual distance between the arch rib segments was measured, and the materials were cut and prepared according to the measured data. After the materials were cut, they were lifted to the installation position using cable hoists and the positioning was assisted.

[0080] The welding of the butt sleeve ring weld is carried out symmetrically, and the weld gap is controlled by a positioning plate before welding.

[0081] After the weld has cooled slightly, knock off the slag and remove any spatter.

[0082] Welding of the cladding plates should be organized according to the assembly line operation, and the number of delays should be controlled within 2 sections.

[0083] (11) Arch foot fixation (sealed hinge)

[0084] Before sealing the hinge, remove temporary adjustment measures such as transverse wind cables and remove additional loads on the arch ribs that are inconsistent with the construction plan to ensure that the actual stress state at the arch foot of the current segment is consistent with the theoretical state.

[0085] Before sealing the hinge, the installed segments are re-measured, and the alignment is fine-tuned based on the re-measurement results. The alignment fine-tuning is carried out on cloudy days or at night, and the timing of the fine-tuning is when the temperature of the steel pipe and steel strand reaches the design temperature range (20±2℃) at the same time.

[0086] Linear fine-tuning targets: The deviation between the measured cable force and the cable force of the sealing hinge target under monitoring instructions is no greater than 5%; the deviation between the measured coordinates of the arch rib control points and the coordinates of the sealing hinge control points under monitoring instructions is less than 5mm; the relative height difference between the coordinates of the upstream and downstream arch rib control points is less than 5mm.

[0087] After fine-tuning is completed and before formal hinge sealing, the actual temperature of the steel pipe segment and steel strand and the arch foot shape must be continuously observed. The hinge sealing time should be selected on cloudy days or at night, and the cantilever segment measuring point elevation reaching the monitoring command elevation is used as the judgment condition for formal hinge sealing.

[0088] When the hinge is officially closed, the hinge weld should be carried out simultaneously on all 8 chords. The welding of each steel pipe should follow the principle of circumferential multi-point symmetrical welding to avoid additional deformation of the arch rib due to welding shrinkage.

[0089] The hinge locking is completed once the base welding of the interlocking section of the 8 main chords is finished.

[0090] After the root pass welding is completed, the subsequent filler weld is carried out under stable environmental conditions such as cloudy days or nighttime, while maintaining symmetrical welding of upstream and downstream.

[0091] (12) Arch closure

[0092] Timing of closure: Continuous observation of temperature and linear changes in the early stage of closure, and selection of the period with the lowest and relatively stable temperature within a day for the main arch closure construction;

[0093] Fine-tuning of alignment: In order to improve the alignment accuracy of the closure and minimize the relative alignment deviation of corresponding segments on both banks, fine-tuning of alignment is carried out on the last two segments installed. This is done on cloudy days or at night. The relative deviation of the penultimate segment is controlled within 5mm, and the relative deviation of the last segment is controlled within 2mm.

[0094] After the final section of the wind brace is installed, only the punch nails and ordinary bolts are used for temporary fixation. The high-strength bolts will be installed after the closure. Considering that the adjustment at the closure end may be difficult, the wind brace can be removed before adjustment, thus reserving adjustment means for any adverse situations that may occur later.

[0095] Closure construction: On the night of the closure, the temperature and alignment change patterns are continuously observed. When the closure temperature is reached and the alignment is close to the theoretical alignment, the hand-operated hoist is gradually tightened to temporarily lock the arch rib. The high bolts are quickly tightened. Under constant temperature, all high bolts are tightened to complete the closure and locking of the arch rib.

[0096] Measure the actual dimensions of the closure joint at the closure temperature, cut the material according to the measured dimensions, and complete the welding of the arch rib cladding plate.

[0097] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for installing arch ribs of a long-span, upper-bearing arch bridge, characterized in that, The following steps are adopted: (1) Establish a finite element model on the computer according to the design dimensions of the arch bridge, and calculate the stress-free length or stress-free curvature data of each component; (2) The factory processes the components according to the data in step (1) to obtain the actual processing model of the components. Through the actual processing model and theoretical deformation calculation, the high-altitude positioning data is determined. (3) The actual three-dimensional posture is obtained by three-dimensional scanning of the initial positioning posture of the component hoisting. The target coordinates of the three-dimensional posture fine adjustment control point are automatically analyzed by digital pre-assembly technology, and the three-dimensional posture is dynamically adjusted in real time by a fully automatic scanning robot. (4) Transport all components to the construction site for installation and positioning, introduce measurement robots and automated monitoring technology, observe the temperature linear change law of the installed arch rib segments, conduct big data statistical analysis, obtain the corresponding functions and related parameters, and make corrections when positioning the arch rib segments to be installed; (5) The arch rib segment is pulled by a single strand of the back-cling cable to prevent the steel strands from getting tangled and twisted, maintain the alignment of the arch rib segment, control the unbalanced force of the back-cling cable and the deflection of the back-cling tower, and ensure the safety of the structure. (6) Control the uniformity of the back cable force, control the balanced tension, control the deviation of the buckle tower, control the arch rib line, and install the wind brace synchronously. Control the continuous and precise installation of the arch rib segments until the arch rib is closed.

2. The method for installing arch ribs of a long-span, upper-bearing arch bridge according to claim 1, characterized in that, In step (1), based on the theory of the stress-free state method, under the determined load and boundary conditions, the stress-free length of the component is consistent with that of its stress-free state, and the completed bridge state is consistent with the target state. According to the construction steps of the bridge, a finite element model is established to calculate the stress-free length or stress-free curvature of the component.

3. The method for installing arch ribs of a long-span, upper-bearing arch bridge according to claim 1, characterized in that, In step (2), the factory processes the data. After the component is processed, the actual processing model of the component is obtained. The high-altitude positioning data is determined by the actual processing model and theoretical deformation calculation. When positioning the component at high altitude on site, the manufacturing processing state is restored to achieve high-altitude precise docking of the arch rib.

4. The method for installing arch ribs of a long-span, upper-bearing arch bridge according to claim 3, characterized in that, Mathematically, a connection equation is established between the cable force before the sealing hinge and closure of the steel pipe arch bridge and the arch rib shape and stress after the cable is removed and the arch is formed. A full-process optimal mathematical model with coupled multi-boundary constraints is established. Develop a program to calculate the optimal single-pass tensioning force throughout the entire process.

5. The method for installing arch ribs of a long-span, upper-bearing arch bridge according to claim 1, characterized in that, In step (3), the three-dimensional scanning model of the prototype reset control theory is used as the target to perform a three-dimensional scan of the initial positioning posture of the hoisting to obtain the actual three-dimensional posture. The target coordinates of the three-dimensional posture fine adjustment control point are automatically analyzed by digital pre-assembly technology, and the three-dimensional posture is dynamically adjusted in real time by a fully automatic scanning robot, thereby improving the three-dimensional accuracy of the arch rib installation.

6. The method for installing arch ribs of a long-span, upper-bearing arch bridge according to claim 1, characterized in that, In step (4), the factors affecting the installation and positioning of the arch rib include temperature and wind speed, which are coupled together, and are also related to the back ties, tower offset, and arch rib deformation.

7. The method for installing arch ribs of a long-span, upper-bearing arch bridge according to claim 1, characterized in that, In step (5), the back strap adopts a single-strand traction method to prevent the steel strands from getting tangled and twisted; the automatic continuous pretensioning equipment is used to ensure that the pretension force of a single cylinder is equal by using the principle that the internal pressure of the communicating vessel is the same.

8. The method for installing arch ribs of a long-span, upper-bearing arch bridge according to claim 1, characterized in that, In step (6), the balancing tension is carried out according to the program by integrating multiple jacks for control.

9. The method for installing arch ribs of a long-span, upper-bearing arch bridge according to claim 8, characterized in that, It includes at least four jacks.

Images