Thin plate multi-rib triangular bridge cantilever steel member and manufacturing method thereof

Abstract

This invention discloses a thin-plate, densely ribbed triangular cantilever steel component for bridges and its manufacturing method. The steel component includes a maintenance walkway top plate unit, a vent bottom plate unit that intersects with and widens therewith, a partition plate welded to the inner surface of the top and bottom plate units, and a guide plate forming a flat triangular closed structure with the top and bottom plate units. Both the maintenance walkway top plate unit and the vent bottom plate unit utilize topology-optimized variable-thickness steel plates. The manufacturing method includes: CNC blanking based on BIM modeling and variable-density topology optimization; high-precision bending using an adaptive control algorithm for real-time adjustment; assembly using an anti-deformation jig and a pre-defined "inverted" assembly jig; optimization of the welding sequence using a genetic algorithm; and smooth rotation via a six-degree-of-freedom synchronous hoisting system after hoisting. This invention, through integrated structural design and systematic process control, achieves efficient integration and performance improvement of maintenance functions and wind resistance aerodynamic effects, while ensuring high-precision and high-quality manufacturing of the thin-walled, densely ribbed component.

Description

Technical Field

[0001] This invention belongs to the field of bridge manufacturing technology, and more specifically, relates to a thin-plate dense-rib triangular bridge cantilever steel component and its manufacturing method. Background Technology

[0002] In recent years, suspension bridges have become the preferred structural solution for long-span sea-crossing bridges due to their ultra-long span capacity, unique structural form, rational stress system, and aesthetically pleasing design. Simultaneously, suspension bridges, with their unique technological advantages, are helping my country's sea-crossing bridge technology reach international leading levels. As a crucial component of the steel box girder of a suspension bridge, cantilever steel members not only undertake structural connection and load transfer functions but also play a key role in the bridge's wind-resistant design. They are typically located at both ends of the steel box girder, extending outwards to form a streamlined structure, known as a "wind vane." By optimizing the aerodynamic shape, they improve the bridge's airflow characteristics, suppress wind-induced vibrations such as flutter and galloping, and ensure the bridge's aerodynamic stability and operational safety under strong winds. Therefore, the manufacturing quality of the cantilever steel members directly affects the wind resistance and structural safety of the entire suspension bridge.

[0003] Traditional suspension bridge steel box girders utilize relatively simple cantilever steel components, typically consisting of two independent parts: a vent unit block and a maintenance walkway block. These components are simple in construction, small in size, and have a large plate thickness, resulting in less welding work during manufacturing. Welding shrinkage deformation is easily controlled, and the overall components exhibit high stiffness and good stability. Furthermore, they have low tooling requirements and mature manufacturing processes with well-established technology and engineering experience. However, these traditional structures have limitations in functional integration, aerodynamic optimization, and lightweighting, making it difficult to meet the demands of modern long-span suspension bridges for high-performance, lightweight, and integrated components. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a thin-plate densely ribbed triangular cantilever steel component for bridges and its manufacturing method. By using topologically optimized inspection road top plate unit, vent bottom plate unit, and partition plate, the structural weight is reduced. Furthermore, by using stiffening ribs and guide plates to form a thin-plate densely ribbed triangular cantilever steel component, the functional integration, aerodynamic optimization effect, and lightweighting are improved. Through system process control, high-precision and high-quality manufacturing is ensured.

[0005] To achieve the above objectives, according to one aspect of the present invention, a thin-plate, densely ribbed triangular bridge cantilever steel member is provided, comprising a maintenance walkway top plate unit, a vent bottom plate unit, multiple partitions, and a guide plate. The air nozzle base plate unit is precisely bent and formed, and then joined to the maintenance walkway top plate unit to form the two main sides of the triangular bridge cantilever steel component. Multiple partitions are welded at intervals to the inner surfaces of the maintenance passage top plate unit and the air nozzle bottom plate unit to form a "groove-shaped" spatial frame structure; The guide plate is welded to the maintenance tunnel top plate unit and the air nozzle bottom plate unit to form a closed triangular structure, and the upper surface of the guide plate is welded to the corresponding partition plate. Both the maintenance access top plate unit and the air nozzle bottom plate unit are made of topology-optimized variable thickness steel plate; the partition adopts a perforated lightweight structure with a perforation layout optimized by topology.

[0006] Furthermore, the surface of the inspection tunnel top plate unit is pre-embedded with a fiber optic grating (FBG) strain sensor mounting groove for structural health monitoring during service life.

[0007] Furthermore, the inner side of the inspection tunnel top plate unit is welded with a continuous longitudinal rib, and the outer side of the air nozzle bottom plate unit is provided with closely spaced ribs.

[0008] Furthermore, the guide plate is streamlined and its surface is coated with a superhydrophobic nanocomposite coating.

[0009] According to another aspect of the present invention, the present invention provides a method for manufacturing a thin-plate, densely ribbed triangular bridge cantilever steel member, for manufacturing the aforementioned thin-plate, densely ribbed triangular bridge cantilever steel member, comprising the following specific steps: S100: Computer BIM 3D modeling and layout of each component of the steel structure, and topology optimization of the inspection road top plate unit, vent bottom plate unit and partition based on the variable density method (SIMP) to generate non-uniform thickness thin plates. All steel plate components are cut by CNC precision cutting or laser cutting. S200: The butt joint of the nozzle base plate and the inspection tunnel top plate is machined and welded with a bevel, and the nozzle base plate is precision bent. S300: On the anti-deformation frame platform, the nozzle bottom plate unit and closely spaced ribs, the guide plate and the horizontal and vertical stiffening ribs, as well as the maintenance lane top plate unit and the continuous longitudinal ribs are assembled respectively; after pre-assembly, the three-dimensional laser scanning is compared with the BIM model, and the out-of-tolerance parts are automatically marked for rework. S400: Design a special assembly jig for "inverted" steel components. The jig support surface matches the shape of the steel components, and the platform flatness is ≤1mm. A positioning baseline is generated. S500: The air nozzle base plate unit is hoisted onto the "inverted" special assembly jig for precise positioning and fastening as the main reference. The inspection road top plate unit and partition are then positioned and assembled in sequence to form a "trough-shaped" component. S600: Assemble transverse and longitudinal stiffening ribs on a "channel-shaped" component and perform symmetrical and uniform welding according to the welding sequence optimized by a genetic algorithm; S700: Position and assemble the guide plate on the welded "trough-shaped" component, and use process stiffening plates to assist in fixing it to ensure flatness accuracy; S800: Use hoisting equipment to lift the steel components off the jig and turn them over to the finished product state.

[0010] Furthermore, in step S100, the objective of the topology optimization is to minimize structural flexibility, with a constraint that the volume fraction does not exceed 85%. ; in, r e For the first e The relative density of each element, where K is the stiffness matrix and U is the displacement vector. V 0 represents the maximum permissible volume; After optimization, the thickness gradient area is marked by the BIM model, and the CNC cutting equipment automatically adjusts the cutting parameters according to the thickness gradient to control the geometric dimension accuracy deviation of each component to within 1mm.

[0011] Further, in step S200, before bending, the initial residual stress field of the air nozzle base plate unit is scanned by X-ray diffraction or ultrasonic method to establish an initial stress database; the adaptive control algorithm adjusts the bending process parameters in real time based on the initial stress database, and the target bending angle, bending force and feed speed are corrected in real time using a model predictive control framework. ; In the formula, i target For the target bending angle, k Index for the current time, i For the prediction step index, H p To predict the time domain, H u To control the time domain, for k Always looking towards the future k + i Predict the bending angle at all times, Δu( k + i | k ) represents the predicted control input increment. Q and R This is the weight matrix.

[0012] Further, in step S300, an industrial 3D laser scanner is used to acquire actual geometric data, which is then used for iterative nearest point (ICP) registration with the BIM model to calculate the root mean square error (RMSE) of the point cloud. ; For the first i Laser scan spatial coordinates of each measured point For the first i Design coordinates in the BIM model of each corresponding point, It is the Euclidean norm.

[0013] Furthermore, in step S400, the positioning baseline is generated by a dynamic laser projection system and thermal expansion is automatically compensated according to the ambient temperature.

[0014] Further, in step S600, the genetic algorithm optimizes the welding sequence with the objective function of minimizing the total welding deformation energy: ; Where Ω represents the entire volume domain of the welded component, in mm³; ε represents the welding residual strain tensor; and D represents the material elasticity matrix, in MPa. The unit is the elastic strain energy density per unit volume, in MPa.

[0015] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. This invention discloses a thin-plate, densely ribbed triangular cantilever steel component for bridges. The top plate of the maintenance walkway and the bottom plate of the ventilator are connected by a bevel, and rigidly connected by densely distributed partitions and stiffening ribs. A guide plate is then used to form a continuous triangular box that combines structural load-bearing capacity and aerodynamic shape, thus creating the thin-plate, densely ribbed triangular cantilever steel component. This invention solves the problems of poor functional integration, aerodynamic optimization, and lightweighting caused by the separate design of the ventilator unit blocks and maintenance walkway blocks in traditional cantilever steel components. The component of this invention eliminates the weak connections and aerodynamic interference between the traditional separate blocks, achieving a highly efficient integration and improved performance of maintenance functions and wind-resistant aerodynamic effects.

[0016] 2. This invention discloses a thin-plate, densely-ribbed triangular bridge cantilever steel member. The top plate unit of the maintenance walkway, the bottom plate unit of the ventilator, and the partition plate employ topology optimization design based on the variable density method (SIMP) to generate a non-uniform thickness thin plate, allowing for a rational material distribution according to the stress path. Simultaneously, densely distributed stiffening ribs are set on the inner sides of the top and bottom plates, forming a "dense-ribbed" system. This combination of topology optimization, variable thickness, and dense ribs significantly enhances the local buckling resistance of the member while reducing structural weight, optimizes structural stiffness through overall stress optimization, and maximizes material utilization.

[0017] 3. The present invention provides a method for manufacturing thin-plate densely ribbed triangular bridge cantilever steel components, which employs computer BIM three-dimensional modeling and layout, CNC or laser cutting to ensure that the geometric dimensional accuracy deviation of each plate unit of the steel component is ≤1mm, and the manufacturing accuracy of each unit is high, thus guaranteeing the manufacturing quality of the steel components.

[0018] 4. A method for manufacturing thin-plate, densely ribbed triangular bridge cantilever steel components according to the present invention employs a pre-set reverse deformation jig for welding and assembling each component, actively counteracting shrinkage and warping after welding and cooling. In the overall assembly stage, a special "inverted" assembly jig is used, with its top support surface pre-set with the steel component assembly line shape (line shape error ≤ 0.5mm, flatness ≤ 1mm), and embedding a piezoelectric ceramic fine-tuning unit and a dynamic laser projection positioning system, which can automatically compensate for thermal expansion according to ambient temperature. This inverted assembly method transforms complex three-dimensional spatial positioning into two-dimensional assembly on a precise jig, ensuring the consistency between the overall geometric shape and design line of the component from a tooling perspective, thus ensuring manufacturing accuracy and quality requirements. Attached Figure Description

[0019] Figure 1 This is a structural schematic diagram of a thin-plate, densely ribbed triangular bridge cantilever steel member according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating a method for manufacturing a thin-plate, densely ribbed triangular bridge cantilever steel component according to an embodiment of the present invention. Figure 3 This is a schematic diagram illustrating the manufacturing process of a thin-plate, densely ribbed triangular bridge cantilever steel component according to an embodiment of the present invention. Figure 4 This is a schematic diagram illustrating the welding sequence of the weld seam of a thin-plate, densely ribbed triangular bridge cantilever steel component according to an embodiment of the present invention. Figure 5 This is a three-dimensional structural diagram of a thin-plate, densely ribbed triangular bridge cantilever steel member installed on a steel box girder, according to an embodiment of the present invention. Figure 6 This is a front view of a thin-plate, densely ribbed triangular bridge cantilever steel member installed on a steel box girder, according to an embodiment of the present invention.

[0020] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1-maintenance tunnel top plate unit, 2-air nozzle bottom plate unit, 3-partition plate, 4-guide plate, 5-steel box girder. Detailed Implementation

[0021] 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 embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Example 1 like Figure 1As shown, this embodiment of the invention provides a thin-plate, densely ribbed triangular cantilever steel component for bridges, including a maintenance walkway top plate unit 1, a vent bottom plate unit 2, partitions 3, and a guide plate 4. The vent bottom plate unit 2 is precision bent and formed, and is joined to the maintenance walkway top plate unit 1, forming two main sides of the flat triangle of the bridge cantilever steel component. Multiple partitions 3 are spot-welded to the inner surfaces of the maintenance walkway top plate unit 1 and the vent bottom plate unit 2, forming a "groove-like" component. The guide plate 4 is welded to the maintenance walkway top plate unit 1 and the vent bottom plate unit 2 to form a closed triangle, and the upper surface of the guide plate 4 is welded to multiple corresponding partitions 3. All components together form an integral triangular structure with a sealed internal space. The maintenance access roof plate unit 1 is made of topology-optimized variable thickness steel plate, with a continuous closed longitudinal rib welded on the inner side, which has both bending and torsional resistance functions; the surface is pre-embedded with fiber grating (FBG) strain sensor mounting slots for embedding fiber grating sensor arrays for structural health monitoring during service.

[0023] The nozzle base plate unit 2 is made of topology-optimized variable thickness steel. It is formed by precision bending of high-strength weather-resistant steel with a bending angle tolerance of ≤1°. The outer side is equipped with densely arranged plate ribs. The connection between the plate ribs and the nozzle base plate unit 2 is made of full penetration fillet weld, which meets the Class I weld standard.

[0024] The partition 3 adopts a lightweight design with openings, and the hole layout is topologically optimized.

[0025] The guide plate 4 is streamlined and has horizontal and vertical stiffening ribs. The surface is coated with a superhydrophobic nanocomposite coating, which effectively suppresses rainwater adhesion and wind-induced vortex vibration.

[0026] The triangular bridge cantilever steel component has dimensions of 18m in length, 4.3m in width, and 0.9m in height. In this embodiment of the invention, the steel component is flat and long with a small steel plate thickness. Topological optimization can reduce the structural weight. In addition, the densely distributed stiffening ribs form a "dense rib" system, which ensures local stability while reducing weight.

[0027] Example 2 like Figure 2 and Figure 3 As shown in the figure, an embodiment of the present invention provides a method for manufacturing a thin-plate, densely ribbed triangular cantilever steel member for bridges, comprising the following specific steps: S100: Steel Component Cutting: Computer BIM 3D modeling and lofting are performed on each component of the thin-plate, densely ribbed triangular bridge cantilever steel structure. Based on the Variable Density Method (SIMP), topology optimization is performed on the maintenance ramp top plate unit 1, vent bottom plate unit 2, and partition plate 3, with the objective of minimizing structural compliance and constraining the volume fraction to not exceed 85%. ; in, r e For the first e The relative density of each element, where K is the stiffness matrix and U is the displacement vector. V 0 represents the maximum allowable volume.

[0028] r e An improved variable density interpolation model (SIMP) is used to penalize the elastic modulus: ; In the formula, E 0 represents the elastic modulus of the solid material. E min represents the minimum elastic modulus of the void element to avoid numerical singularities. p The penalty factor is dynamically and adaptively adjusted during the iteration process. ; in, p (k) For the first k The penalty factor for the next iteration p 0 is the initial penalty factor. l For adaptive adjustment coefficient, K max This represents the maximum number of iterations. This dynamic penalty strategy can suppress intermediate density units in the early stages of optimization and accelerate convergence to a 0 / 1 distribution in the later stages of optimization.

[0029] After optimization, a non-uniform thickness thin plate is generated, and the thickness gradient area is marked through the BIM model. All steel plate components are cut by CNC precision cutting or laser cutting. The equipment automatically adjusts the cutting parameters according to the thickness gradient to control the geometric dimension accuracy deviation of each component to be within 1mm. S200: Steel component processing: The butt joint of the nozzle base plate unit 2 and the inspection road top plate unit 1 is processed with welding bevels, and the nozzle base plate unit 2 is bent with high precision using a high-precision bending machine, with a bending angle tolerance of ≤1°. Before bending, the initial residual stress field of the bottom plate unit 2 of the air nozzle is scanned by X-ray diffraction or ultrasonic method to establish an initial stress database containing stress amplitude, direction and spatial distribution; the residual stress field adopts the following polynomial interpolation model: ; in, x The coordinates are along the length of the steel plate. y The coordinates are along the width of the steel plate. z The coordinates are along the thickness direction of the steel plate; m , n , l They are respectively x, y , z The highest order of the polynomial in the direction; i , j , k For the corresponding power index; a ijk These are the fitting coefficients. s rand The term is a random perturbation based on measured data, which follows a Gaussian distribution.

[0030] The bending process parameters are adjusted in real time by an adaptive control algorithm that integrates theoretical springback models with experimental data feedback. ; in, i target For the target bending angle, i design To design the bending angle, Δ i springback The rebound angle is Δ. i res This is an additional springback correction term caused by the initial residual stress.

[0031] Springback angle Δ i springback The calculation is performed using an improved incremental constitutive model: ; in, k For material coefficients, s y For yield strength, E For elastic modulus, t For plate thickness, R Where is the bending radius, s u For tensile strength, or The material hardening sensitivity coefficient, f ( n ) is the Poisson ratio correction function, and its expression is: ; Correction term Δ due to residual stress i res Obtained by integrating the stress field along the plate thickness direction: ; The adaptive control algorithm is based on an initial stress database and uses a model predictive control (MPC) framework to correct the target bending angle, bending force, and feed rate in real time. ; In the formula, k Index for the current time, iFor the prediction step index, H p To predict the time domain, H u To control the time domain, for k Always looking towards the future k + i Predict the bending angle at all times, where u is the control input vector (including bending force, feed rate, etc.), Δu( k + i | k ) represents the predicted control input increment. Q and R This is the weight matrix. The algorithm dynamically adjusts the subsequent bending stroke by providing real-time feedback on the deviation between the measured bending angle and the model's predicted value, compensating for the nonlinear springback caused by the initial residual stress.

[0032] S300: Pre-assembly of components: Place the bent nozzle base plate unit 2 on the anti-deformation jig platform, assemble and weld its outer ribs, and simultaneously assemble and weld the guide plate 4 and its attached transverse and longitudinal stiffening ribs on the anti-deformation jig platform, as well as assemble and weld the inspection tunnel top plate unit 1 and its inner longitudinal ribs. The anti-deformation jig is pre-set with a reverse deformation amount based on welding simulation and process tests to actively counteract the shrinkage deformation generated after welding cooling. Before spot welding, all pre-assembled units are equipped with actual geometric data obtained using an industrial 3D laser scanner. This data is then used for iterative nearest point (ICP) registration with the BIM model, and the root mean square error (RMSE) of the point cloud is calculated. ; For the first i Laser scan spatial coordinates of each measured point For the first i Design coordinates in the BIM model of each corresponding point, It is the Euclidean norm.

[0033] The objective function for ICP registration is an improved least-squares form with a weight matrix: ; Where R is the rotation matrix, t is the translation vector, and the weights are... w i Dynamic assignment based on point-pair curvature similarity: ; and These are the curvature estimates for the scanned points and the CAD model points, respectively. This is the average curvature normalization factor. Out-of-tolerance parts are automatically marked for rework to ensure pre-assembly accuracy.

[0034] S400: Special jig preparation: Design a special jig for "inverted" steel components. The jig has a pre-set assembly line of steel components with a line error of ≤0.5mm. The top support surface of the jig matches the shape of the inspection road top plate unit 1 and the air nozzle bottom plate unit 2, and the flatness of the top surface of the jig platform is ≤1mm. The top support surface of the tire frame is embedded with a piezoelectric ceramic fine-tuning unit with a stroke of ±2mm and a resolution of 0.01mm. The positioning baseline is generated by a dynamic laser projection system and automatically compensates for thermal expansion according to the ambient temperature. ; among them,L corrected The length of the baseline after temperature correction, in mm; L 0 The design length is given at standard temperature, in mm. α The coefficient of linear expansion of steel, unit: / ° C ; β This is the nonlinear thermal expansion correction factor, in units of: / °C²; T Current ambient temperature, unit: °C C ; T 0 Standard reference temperature, unit: °C C .

[0035] The positioning baseline generation of the dynamic laser projection system adopts a real-time closed-loop control strategy: ; ; In the formula, r desired (t) is the theoretical projection position vector, r actual (t) represents the measured value of the actual projected position, K p K i K d The proportional, integral, and differential gain matrices are determined by optimization using the pole placement method, ensuring that the dynamic tracking accuracy of the projected baseline is better than 0.05mm.

[0036] S500: Inverted Assembly Welding of Main Structure: The bottom plate unit 2 of the air nozzle is hoisted onto the "inverted" special assembly jig, and the pre-set positioning baseline on the jig is used for precise positioning and fastening, making it the main reference for the assembly of the entire steel component. The inspection road top plate unit 1 and the positioning assembly partition 3 are then positioned and assembled to form a "trough-shaped" component; specifically, it includes: S501: The completed rib welded nozzle base plate unit 2 is smoothly hoisted onto the "inverted" assembly jig using lifting equipment. During the process, the nozzle base plate unit 2 is guided so that its outer contour is gradually aligned with the three-dimensional spatial positioning baseline on the jig support surface. This baseline system is constructed using high-precision laser projection to define the theoretical position of the component in the X (length), Y (width), and Z (height and line shape) directions. After the nozzle base plate unit 2 is initially positioned, it is fine-tuned and finally tightened using the modular adjustable clamps provided on the jig.

[0037] S502: Lift the maintenance passage top plate unit 1 with the spot-welded continuous longitudinal ribs and slowly lower it. At the same time, using the air nozzle bottom plate unit 2 as a reference, observe its relative position with the air nozzle bottom plate unit 2, control and adjust the design port distance and parallelism between the two, and accurately position the maintenance passage top plate unit 1. After positioning, use intermittent spot welding (weld length about 30-50mm) at both ends and key points in the middle to temporarily fix the maintenance passage top plate unit 1 and the air nozzle bottom plate unit 2 to form an open structure.

[0038] S503: Each prefabricated partition 3 is sequentially hoisted and vertically inserted into the opening structure formed by the maintenance walkway top plate unit 1 and the air nozzle bottom plate unit 2. A multi-view vision measurement system is used to monitor the partition's posture in real time. Combined with tools such as a right-angle ruler, laser line projector, or level, the verticality of the partition 3 is strictly controlled to ensure that its verticality deviation from the reference air nozzle bottom plate unit 2 is ≤1mm. After each partition 3 is accurately positioned, it is immediately fixed by symmetrical spot welding at its contact edges with the air nozzle bottom plate unit 2 and the maintenance walkway top plate unit 1 to ensure its stable position. The air nozzle bottom plate unit 2, the maintenance walkway top plate unit 1, and the partition 3 together constitute a stable, upward-facing, "groove-shaped" spatial frame structure.

[0039] S600: Stiffening and Welding: Horizontal and longitudinal stiffening ribs are assembled on the "channel-shaped" component, and all welds are integrally welded. The welding sequence of all welds is optimized using a genetic algorithm, with the goal of minimizing the overall welding deformation energy. ; Where Ω represents the entire volume of the welded component, in mm³; e Where D is the welding residual strain tensor, and D is the material elasticity matrix, in MPa; The unit is the elastic strain energy density per unit volume, in MPa.

[0040] Welding residual strain tensor e It consists of three parts: thermal strain, phase transformation strain, and plastic strain. ; Among them, thermal strain e thermal =αT ( T - T 0)I, α T is the coefficient of thermal expansion, and I is the unit tensor.

[0041] The fitness function optimized by the genetic algorithm incorporates multidimensional evaluation metrics: ; In the formula, s is the welding sequence encoding sequence. E def (s) represents the predicted welding deformation energy, Δ max (s) represents the maximum deformation. L total (s) represents the total length of the welding path. E max , , For the corresponding normalization factor, w 1. w 2. w 3 is the weighting coefficient that satisfies w 1+ w 2+ w 3=1. The welding sequence coding adopts an ordinal coding strategy based on topological sorting to ensure the pre-constraint relationship between welds.

[0042] The specific welding sequence is as follows: Figure 4 As shown, the steps are as follows: Step ①: Simultaneously weld the butt joint of the inspection tunnel top plate unit and the vent bottom plate unit from the middle of the component towards both ends; Step ②: Simultaneously weld the central partition plate from the middle to both sides; Step ③: Sequentially weld the transverse ribs at both ends of the central partition plate from the middle to the sides; Step ④: Sequentially weld adjacent partition plates from the middle to both sides; Step ⑤: Repeat Step ③, sequentially welding adjacent transverse ribs from the middle to the sides; Step ⑥: Repeat Step ④, sequentially welding adjacent partition plates from the middle to both sides; Step ⑦: Sequentially weld the inner longitudinal ribs from the middle to both ends; Step ⑧: Sequentially weld the outer longitudinal ribs from the middle to both ends. All welds are completed symmetrically and evenly from the inside out, with the back welds welded in the same direction as the front welds.

[0043] S700: Deflector Assembly: Deflector 4 is positioned and assembled on the welded "trough-shaped" component. During assembly, process stiffening plates are used to assist in fixing and ensure flatness accuracy. Subsequently, the deflector component is fixedly connected to the "trough-shaped" component. The process stiffening plates prevent warping and deformation of deflector 4 during assembly, ensuring the flatness accuracy of the deflector and ensuring its normal functioning in wind resistance and deflection. S800: Finished Product Forming: Using specialized hoisting equipment, the steel component is lifted from the jig and unloaded. Then, using specialized turning lugs, the steel component is safely and smoothly turned to its finished product state, minimizing potential deformation during hoisting. At this point, the manufacturing of the thin-plate, densely ribbed triangular bridge cantilever steel component is complete. Finally, the steel component is installed on both sides of the steel box girder 5 (e.g., ...). Figure 5 and Figure 6 (As shown).

[0044] The turning process employs a six-degree-of-freedom synchronous hoisting system, using gyroscopes to monitor attitude in real time and control angular acceleration to ≤0.5 rad / s², minimizing hoisting deformation. The optimal trajectory planning during hoisting is based on a time-energy dual-objective optimization model. ; ; Where q(t) is a six-degree-of-freedom generalized coordinate vector. and They are velocity and acceleration, respectively. r As the energy penalty weight, this optimization can obtain a smooth motion trajectory that minimizes hoisting deformation.

[0045] This invention integrates the traditionally separate air nozzle unit blocks with the maintenance walkway block into a flat, triangular, sealed structure. This structure, comprised of a maintenance walkway top plate unit, a bent air nozzle bottom plate unit, internal partitions, and guide plates, achieves structural and functional integration. Rigidly connected by densely packed partitions and stiffening ribs, it forms a continuous triangular box that combines structural load-bearing capacity with aerodynamic shape. The streamlined air nozzle bottom plate and guide plates together form a continuous, smooth, streamlined aerodynamic shell, serving as an aerodynamic guide surface. This effectively guides and optimizes the wind field distribution near the bridge deck, significantly suppressing wind-induced vibrations such as flutter. Simultaneously, the flat maintenance walkway top plate and stable internal space provide a safe passage for routine bridge inspection and maintenance. This integrated design not only eliminates the weaknesses and aerodynamic interference between traditional separate blocks but also optimizes structural stiffness through overall stress distribution, achieving a highly efficient integration and performance enhancement of maintenance functions and wind-resistant aerodynamic effects.

[0046] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thin-plate, densely ribbed triangular cantilever steel member for bridges, characterized in that, It includes a maintenance access top plate unit (1), a nozzle bottom plate unit (2), multiple baffles (3) and a guide plate (4). The bottom plate unit (2) of the air nozzle is precisely bent and formed to connect with the top plate unit (1) of the maintenance road, forming the two main sides of the triangular bridge cantilever steel component. Multiple partitions (3) are welded at intervals to the inner surfaces of the maintenance passage top plate unit (1) and the air nozzle bottom plate unit (2) to form a "groove-shaped" spatial frame structure; The guide plate (4) is welded to the maintenance deck top plate unit (1) and the nozzle bottom plate unit (2) to form a closed triangular structure, and the upper surface of the guide plate (4) is welded to the corresponding partition plate (3). The inspection tunnel top plate unit (1) and the air nozzle bottom plate unit (2) are both made of topology-optimized variable thickness steel plates; the partition plate (3) adopts an open lightweight structure with topology-optimized hole layout.

2. The thin-plate, densely ribbed triangular bridge cantilever steel member according to claim 1, characterized in that, The surface of the inspection tunnel top plate unit (1) is pre-embedded with fiber optic grating (FBG) strain sensor mounting slots for structural health monitoring during service life.

3. A thin-plate, densely ribbed triangular bridge cantilever steel member according to claim 1, characterized in that, The maintenance tunnel top plate unit (1) has a continuous longitudinal rib welded on the inner side, and the air nozzle bottom plate unit (2) has a densely arranged plate rib on the outer side.

4. A thin-plate, densely ribbed triangular bridge cantilever steel member according to claim 1, characterized in that, The guide plate (4) is streamlined and its surface is coated with a superhydrophobic nanocomposite coating.

5. A method for manufacturing a thin-plate, densely ribbed triangular bridge cantilever steel member, used to manufacture a thin-plate, densely ribbed triangular bridge cantilever steel member as described in any one of claims 1-4, characterized in that, The specific steps include the following: S100: Computer BIM three-dimensional modeling and layout of each component of the steel structure, and topology optimization of the inspection road top plate unit (1), the vent bottom plate unit (2) and the partition (3) based on the variable density method to generate non-uniform thickness thin plate, and CNC precision cutting or laser cutting for all steel plate components. S200: The butt joint of the nozzle base plate (1) and the inspection road top plate (2) is machined and welded, and the nozzle base plate (1) is precisely bent; S300: On the anti-deformation frame platform, assemble the nozzle bottom plate unit (2) and densely packed plate ribs, guide plate (4) and transverse and longitudinal stiffening ribs, as well as the maintenance road top plate unit (1) and continuous longitudinal ribs; after pre-assembly, compare with the BIM model through three-dimensional laser scanning, and automatically mark the out-of-tolerance parts for rework; S400: Design a special assembly jig for "inverted" steel components. The jig support surface matches the shape of the steel components, and the platform flatness is ≤1mm. A positioning baseline is generated. S500: The nozzle base plate unit (2) is hoisted onto the "inverted" special assembly jig for precise positioning and fastening as the main reference. The inspection road top plate unit (1) and partition (3) are then positioned and assembled in sequence to form a "trough-shaped" component. S600: Assemble transverse and longitudinal stiffening ribs on a "channel-shaped" component and perform symmetrical and uniform welding according to the welding sequence optimized by a genetic algorithm; S700: Position and assemble the guide plate (4) on the welded "trough-shaped" component, and use process stiffening plates to assist in fixing to ensure flatness accuracy; S800: Use hoisting equipment to lift the steel components off the jig and turn them over to the finished product state.

6. A method for manufacturing a thin-plate, densely ribbed triangular bridge cantilever steel member according to claim 5, characterized in that, In step S100, the objective of the topology optimization is to minimize structural flexibility, with a constraint that the volume fraction does not exceed 85%. ； in, ρ e For the first e The relative density of each element, where K is the stiffness matrix and U is the displacement vector. V 0 represents the maximum permissible volume; After optimization, the thickness gradient area is marked by the BIM model, and the CNC cutting equipment automatically adjusts the cutting parameters according to the thickness gradient to control the geometric dimension accuracy deviation of each component to within 1mm.

7. A method for manufacturing a thin-plate, densely ribbed triangular bridge cantilever steel member according to claim 5, characterized in that, In step S200, before bending, the initial residual stress field of the air nozzle base plate unit (2) is scanned by X-ray diffraction or ultrasonic method to establish an initial stress database. The adaptive control algorithm adjusts the bending process parameters in real time based on the initial stress database, and the model predictive control framework corrects the target bending angle, bending force, and feed rate in real time. ； In the formula, θ target For the target bending angle, k Index for the current time, i For the prediction step index, H p To predict the time domain, H u To control the time domain, for k Always looking towards the future k + i Predict the bending angle at all times, Δu( k + i | k ) represents the predicted control input increment. Q and R This is the weight matrix.

8. A method for manufacturing a thin-plate, densely ribbed triangular bridge cantilever steel member according to claim 5, characterized in that, In step S300, an industrial 3D laser scanner is used to acquire actual geometric data, which is then iteratively registered with the BIM model to determine the nearest point and the root mean square error (RMSE) of the point cloud is calculated. ； For the first i Laser scan spatial coordinates of each measured point For the first i Design coordinates in the BIM model of each corresponding point, It is the Euclidean norm.

9. A method for manufacturing a thin-plate, densely ribbed triangular bridge cantilever steel member according to claim 5, characterized in that, In step S400, the positioning baseline is generated by a dynamic laser projection system and thermal expansion is automatically compensated according to the ambient temperature.

10. A method for manufacturing a thin-plate, densely ribbed triangular bridge cantilever steel member according to claim 5, characterized in that, In step S600, the genetic algorithm optimizes the welding sequence with the objective function of minimizing the total welding deformation energy: ； Where Ω represents the entire volume domain of the welded component, in mm³; ε represents the welding residual strain tensor; and D represents the material elasticity matrix, in MPa. The unit is the elastic strain energy density per unit volume, in MPa.

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