Hidden type support-free pin hinge structure of bridge flexible steel pier

Abstract

The invention discloses a hidden support-free pin hinge structure for a flexible steel pier of a bridge, which comprises a main lug plate, a first through hole, a second through hole, a first hinge pin, a second hinge pin, a second hinge pin and a third hinge pin, and is characterized in that the lower part of the main lug plate is arranged in the steel pier, and the upper part of the main lug plate vertically extends upwards into a main beam box chamber; the pair of secondary lug plates are arranged on the two sides of the main lug plate in parallel in the transverse direction, and the bottom of each secondary lug plate is connected with a bottom plate of a main beam; a second through hole is formed in each secondary lug plate; the pin shaft sequentially penetrates through one second through hole, the first through hole and the other second through hole in the transverse direction to connect the main lug plate with the pair of secondary lug plates; a clamping groove is formed in one end of the pin shaft; and the baffle plate is clamped in the clamping groove, and the baffle plate is connected with one secondary lug plate close to the clamping groove. The problem that the size of the flexible steel pier in the bridge direction does not meet the requirement for the space needed for installing the movable support can be well solved, meanwhile, the pin hinge structure is hidden in the main beam, and on the premise that the mechanical property of the bridge is met, the structure looks simple and attractive.

Description

Technical Field

[0001] The present invention relates to the field of bridge engineering, and more particularly to a bridge flexible steel pier hidden support-free pin hinge structure. Background Art

[0002] During the operation phase of the bridge, the longitudinal horizontal force acting on each flexible pier is relatively small, and most of the longitudinal horizontal force is borne by the abutments and rigid piers. Based on this characteristic, the cross-sectional size of the flexible pier along the bridge direction can be greatly reduced. At present, the main construction method of flexible piers is to use the movable amount of movable bearings to meet the displacement requirements of the bridge structure.

[0003] In some bridge construction projects, due to the limitations of environmental, landscape and overall structural conditions, the use of steel piers as flexible piers is an ideal choice. Steel flexible piers can not only meet the strength requirements, but also further reduce the size of the pier body along the bridge direction, making the bridge structure more simple and beautiful. However, when it comes to bridges with longer lengths such as cable-stayed bridges and arch bridges, the longitudinal displacement of the main beam will increase significantly. In this case, flexible steel piers expose a series of problems. On the one hand, the existing size of the pier body in the longitudinal direction of the bridge is often difficult to meet the space requirements for installing movable bearings; on the other hand, if an attempt is made to solve this problem by increasing the size of the pier body, it will directly lead to a significant increase in the project cost. This situation undoubtedly brings severe challenges to the application of flexible steel piers in long-bridged bridges. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these purposes and other advantages according to the present invention, a bridge flexible steel pier hidden support-free pin hinge structure is provided, which includes:

[0006] The main ear plate, the lower part of which is arranged in the steel pier, and the upper part of which is vertically extended upward to the main beam box room, is arranged in the longitudinal direction; the upper part of the main ear plate is provided with a first through hole, which is an elliptical structure, and the long axis of the first through hole extends in the longitudinal direction; the first through hole is provided with a first bushing;

[0007] A pair of secondary ear plates are arranged in parallel on both sides of the main ear plate in the transverse direction, and the bottom of each secondary ear plate is connected to the bottom plate of the main beam; each secondary ear plate is provided with a second through hole corresponding to the first through hole, and each second through hole is circular; a second bushing is provided in the second through hole;

[0008] A pin shaft, which passes through one of the second through holes, the first through hole and another second through hole in sequence in the transverse direction to connect the main ear plate with a pair of secondary ear plates; a slot is provided on one end of the pin shaft;

[0009] A baffle plate is clamped in the clamping slot, and the baffle plate is connected to a secondary ear plate adjacent to the clamping slot;

[0010] The first bushing and the second bushing are made of graphite copper alloy, and the calculation formula of the thickness t of the first bushing and the second bushing is shown in Formula 1:

[0011]

[0012] Wherein, F is the maximum load transferred from the pier to the bushing, [σ] is the allowable compressive strength of the graphite copper alloy, λ is the heat dissipation coefficient of the bushing, ΔT is the temperature difference between the inner and outer walls of the bushing, α is the correction coefficient, the correction coefficient α1 corresponding to the first bushing thickness t1 and the correction coefficient α2 corresponding to the second bushing thickness t2, and the sum of α1 and α2 is 1.

[0013] Preferably, the bridge flexible steel pier hidden support-free pin hinge structure further comprises:

[0014] A steel plate, which is arranged on the top of the pier, and the steel plate is an arc-shaped structure bent downward;

[0015] A graphite copper lining is arranged on the top of the steel plate.

[0016] Preferably, in the hidden support-free pin hinge structure of the flexible steel pier of the bridge, a plurality of adaptive adjustment blocks are provided at intervals on the inner walls of the first bushing and the second bushing, and the adaptive adjustment blocks are shape memory alloys with wedge-shaped structures.

[0017] Preferably, in the hidden support-free pin hinge structure of the flexible steel pier of the bridge, the upper part of the main ear plate is provided with a first reinforcing plate on both sides along the lateral direction, and the lower part of the main ear plate is provided with stiffening ribs on both sides along the lateral direction; each secondary ear plate is provided with a second reinforcing plate on both sides along the lateral direction.

[0018] Preferably, the bridge flexible steel pier hidden support-free pin hinge structure further comprises:

[0019] A plurality of first impact force sensors are embedded in the upper portion of the main ear plate at intervals, and the first impact force sensors are used to monitor the impact force received by the main ear plate;

[0020] A plurality of second impact force sensors are embedded in the pin shaft at intervals along the axial direction of the pin shaft, and the second impact force sensors monitor the impact force received by the pin shaft;

[0021] A plurality of temperature sensors are arranged on the pin shaft at intervals along the axial direction of the pin shaft, and the temperature sensors are used to monitor the working temperature of the pin shaft in real time;

[0022] A locking mechanism, which is disposed on the first reinforcing plate, and is used to lock the pin shaft;

[0023] A controller is connected to multiple first impact force sensors, multiple second impact force sensors, a temperature sensor, and a locking mechanism; the controller is configured to collect a first detection value of the first impact force sensor, a second detection value of the second impact force sensor, and a third detection value of the temperature sensor, the controller inputs the first detection value, the second detection value, and the third detection value into a pre-constructed connection structure risk prediction model, and outputs a risk warning level of the connection structure. When the risk warning level reaches a preset high-risk threshold, the controller sends an alarm signal and simultaneously activates the locking mechanism to lock the pin shaft.

[0024] Preferably, the risk warning level of the output connection structure of the hidden support-free pin hinge structure of the bridge flexible steel pier has been optimized and adjusted, specifically:

[0025] When the risk warning level is less than the preset high-risk warning value, and the ratio of the first detection value to the theoretical bearing impact force of the main ear plate is greater than 0.6, the controller calculates the change rate of the first detection value within a historical week. If the change rate of the first detection value exceeds 5%, the risk warning level is adjusted to the high-risk threshold.

[0026] Preferably, the optimization and adjustment of the risk warning level of the connection structure of the bridge flexible steel pier hidden type support-free pin hinge structure also includes:

[0027] When the risk warning level is less than the preset high risk warning value and the third detection value is greater than 50°C, the risk warning level is adjusted once for every 5°C increase in the third detection value relative to 50°C. The risk warning level after each adjustment is 1.1 times the value of the previous risk warning level.

[0028] Preferably, in the bridge flexible steel pier hidden support-free pin hinge structure, the controller is further configured to send a low-risk warning signal once every 1 hour if the ratio of the risk warning level after optimization adjustment to the high-risk warning threshold is greater than 0.5 and less than 0.65;

[0029] If the ratio of the risk warning level after optimization and adjustment to the high risk warning threshold is greater than or equal to 0.65 and less than 1, the controller will issue a medium risk warning signal and send it every 0.3 hours;

[0030] If the ratio of the optimized and adjusted risk warning level to the high-risk warning threshold is greater than or equal to 1, the controller sends a continuous high-risk warning signal and starts the locking mechanism to lock the pin.

[0031] Preferably, in the bridge flexible steel pier hidden type support-free pin hinge structure, a plurality of mounting slots are provided on the first reinforcing plate; a plurality of locking holes are provided on the pin shaft, which are arranged one-to-one corresponding to the plurality of mounting slots;

[0032] The locking mechanism comprises:

[0033] A plurality of drivers, one driver is arranged in each installation slot; each driver is connected to a controller;

[0034] A plurality of locking tongues are provided, and each driver has a locking tongue at its output end. Each driver drives the locking tongue to move along the radial direction of the pin shaft and can be inserted into a corresponding locking hole.

[0035] Preferably, in the concealed support-free pin hinge structure of the flexible steel pier of the bridge, both the inlet and outlet ends of the first perforation are flared, the flaring angle is 10 to 20 degrees, and the flaring length is 0.3 to 0.5 times the diameter of the pin shaft.

[0036] The present invention has at least the following beneficial effects:

[0037] The present invention proposes a pin hinge structure for solving the problem that the size of the flexible steel pier body does not meet the space required for installing the movable support, which greatly improves the utilization efficiency of the high-strength material of the steel pier, can further reduce the size of the flexible pier body, and reduces the cost. At the same time, under the premise of meeting the mechanical properties of the bridge, the overall structure appears simple and beautiful.

[0038] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is an elevation view of a bridge flexible steel pier hidden type support-free pin hinge structure described in one of the technical solutions of the present invention;

[0040] Figure 2 A side view of a hidden support-free pin hinge structure of a flexible steel pier of a bridge described in another technical solution of the present invention;

[0041] Figure 3 for Figure 1 Cross-sectional view of AA in the middle;

[0042] Figure 4 It is a structural schematic diagram of a bridge flexible steel pier hidden support-free pin hinge structure described in another technical solution of the present invention;

[0043] Figure 5 It is a structural schematic diagram of a bridge flexible steel pier hidden support-free pin hinge structure described in another technical solution of the present invention;

[0044] Figure 6 It is a schematic structural diagram of a main ear plate in another technical solution of the present invention;

[0045] Figure 7It is a schematic structural diagram of the secondary ear plate in another technical solution of the present invention.

[0046] Explanation of the reference numerals: 1-steel pier; 11-steel plate; 12-graphite copper lining; 2-main ear plate; 21-first through hole; 22-first bushing; 23-first reinforcing plate; 231-installation groove; 24-stiffening rib; 3-secondary ear plate; 31-second through hole; 32-second reinforcing plate; 4-pin shaft; 42-locking hole; 51-driver; 52-locking tongue; 6-baffle; 7-main beam; 71-bottom plate of the main beam. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments so that those skilled in the art can implement the invention with reference to the description.

[0048] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0049] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0050] In the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. to indicate directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0051] like Figures 1 to 7 As shown, the present invention provides a bridge flexible steel pier hidden support-free pin hinge structure, which includes:

[0052] The main ear plate 2, whose lower part is arranged in the steel pier 1, and whose upper part vertically extends upward to the box room of the main beam 7, is arranged in the longitudinal direction ( Figure 2 The main ear plate 2 is provided with a first through hole 21 on the upper part, which is an elliptical structure, and the long axis of the first through hole 21 extends in the longitudinal direction; a first bushing 22 is provided in the first through hole;

[0053] A pair of secondary ear plates 3 are arranged in parallel on both sides of the main ear plate 2 in the transverse direction, and the bottom of each secondary ear plate 3 is connected to the bottom plate 71 of the main beam; each secondary ear plate 3 is provided with a second through hole 31 corresponding to the first through hole 21, and each second through hole 31 is circular; a second bushing is provided in the second through hole;

[0054] The pin 4 is arranged in the transverse direction ( Figure 2 The main ear plate 2 is connected to a pair of secondary ear plates 3 by passing through one of the second through holes 31, the first through hole 21 and another second through hole 31 in sequence; a slot is provided on one end of the pin 4;

[0055] A baffle plate 6 is clamped in the clamping slot and connected to a secondary ear plate 3 adjacent to the clamping slot;

[0056] The first bushing 22 and the second bushing are made of graphite copper alloy, and the calculation formula of the thickness t of the first bushing 22 and the second bushing is shown in Formula 1:

[0057]

[0058] Among them, F is the maximum load transferred from the pier to the bushing, [σ] is the allowable compressive strength of the graphite copper alloy, λ is the heat dissipation coefficient of the bushing, ΔT is the temperature difference between the inner wall and the outer wall of the bushing, α is the correction coefficient, the correction coefficient α1 corresponding to the thickness t1 of the first bushing 22 and the correction coefficient α2 corresponding to the thickness t2 of the second bushing, and the sum of α1 and α2 is 1.

[0059] The present invention provides an innovative hidden support-free pin hinge structure for flexible steel piers of bridges, which aims to solve many problems faced by traditional flexible steel piers of bridges during use and provides a more efficient, economical and reliable solution for the optimization of bridge structures.

[0060] The bridge flexible steel pier hidden type support-free pin hinge structure of the present invention requires the establishment of the overall bridge finite element model simulation calculation. The simulated boundary condition of the flexible pier in the model is hinged. The load or effect of the horizontal force along the bridge direction caused by temperature, braking force, wind load, etc. needs to be considered. The displacement of the flexible pier along the bridge direction is calculated as the theoretical basis for the ear plate opening size. In addition, the ear plate opening size also needs to be combined with the specifications of the pin shaft, so the opening should be elliptical, with the major axis along the bridge direction ( Figure 2 In the flexible steel pier, the pins move in the openings of the ear plates to achieve deformation, which not only meets the requirements of the longitudinal deformation of the bridge, but also solves the problem of not needing to increase the size of the pier to meet the space of the movable bearing, greatly improving the utilization efficiency of the high-strength materials of the steel pier and reducing the cost.

[0061] The bridge flexible steel pier hidden type support-free pin hinge structure of the present invention specifically comprises a main ear plate 2, a secondary ear plate 3, a pin shaft 4, and a baffle 6:

[0062] The main lug plate 2 is one of the core components of the entire pin hinge structure, and its lower part is firmly set in the steel pier 1. In the actual construction process, in order to ensure the close combination of the main lug plate 2 and the steel pier 1, it is necessary to first accurately measure and locate the installation position of the steel pier 1. According to the design requirements, a high-strength welding process is used to connect the lower part of the main lug plate 2 with the preset position of the steel pier 1. This welding process uses advanced welding technology, such as submerged arc welding, to ensure that the penetration depth and width of the welding area meet the strength requirements by accurately controlling the welding current (250A), voltage (30V) and welding speed (5mm / s). At the same time, non-destructive testing methods (such as X-ray flaw detection) are used to strictly inspect the welding quality to prevent welding defects. The steel pier 1 and the main lug plate 2 can be pre-processed in the factory. The upper part of the main lug plate 2 extends vertically upward to the box room of the main beam 7 and is strictly arranged in the longitudinal direction. The upper part of the main ear plate 2 is provided with a first perforation 21, which adopts an elliptical structure. This unique shape design takes into account the deformation requirements of the bridge under various working conditions during use. Its major axis extends in the longitudinal direction, and its size is determined through detailed structural mechanics analysis and finite element simulation. According to the expected deformation of the bridge, the major axis length of the first perforation 21 is accurately calculated to ensure that when subjected to various loads, the main ear plate 2 can have sufficient deformation capacity in the longitudinal direction, thereby adapting to the displacement of the bridge structure and ensuring the stability of the structure. When processing the first perforation 21, high-precision CNC processing equipment is used to control the dimensional accuracy of the major axis and minor axis of the ellipse within ±0.1mm, ensuring the mechanical properties of the main ear plate 2 when transferring loads and adapting to deformation.

[0063] A pair of secondary ear plates 3 plays an important auxiliary supporting and connecting role in the whole structure. A pair of secondary ear plates 3 are arranged horizontally and parallel to the two sides of the main ear plate 2, and each secondary ear plate 3 is provided with a second through hole 31 corresponding to the first through hole 21, and the second through hole 31 is circular. A certain gap is reserved between a pair of secondary ear plates 3 and the main ear plates 2 to meet the lateral deformation of the bridge caused by temperature and the like; in the actual installation process, the lower part of the main ear plate is pre-inserted into the steel pier, and the main ear plate is welded to the steel pier, and the secondary ear plate can be pre-welded to the bottom plate of the main beam 7. After the main ear plate and the steel pier are pre-processed and assembled, they are installed to the preset construction position, and then the main beam 7 welded with the secondary ear plate is hoisted above the steel pier through the hoisting process, and the position is adjusted so that a pair of secondary ear plates are symmetrically located on both sides of the main ear plate, and the main beam 7 is lowered to the bottom plate of the main beam 7 and placed on the top of the steel pier (on the first graphite steel lining). After being lowered into place, the position of the main beam 7 is adjusted so that a pair of second perforations correspond to the first perforations in the horizontal direction to ensure that the pin shaft can smoothly pass through the second perforations and the first perforations;

[0064] The pin 4 passes through the second through hole 31 of one of the secondary ear plates 3, the first through hole 21 of the main ear plate 2, and the second through hole 31 of the other secondary ear plate 3 in the transverse direction, connecting the main ear plate 2 with a pair of secondary ear plates 3. When selecting the material of the pin 4, considering the huge load and complex stress state it bears in the structure, high-strength alloy structural steel is used. Through precise material performance testing, it is ensured that its yield strength (785MPa) and tensile strength (810MPa) meet the design requirements. The processing process of the pin 4 is also very strict. During the processing, its surface is subjected to high-precision grinding and polishing to make the surface roughness reach Ra0.8μm or less, reducing friction resistance and wear during use.

[0065] A slot is provided at one end of the pin 4. The slot is designed to not only firmly hold the baffle 6, but also to ensure that it has sufficient strength and precision. The shape and size of the slot are optimized based on the shape and force analysis of the baffle 6. The optimal size and shape of the slot are determined by simulation using 3D modeling software so that it will not be deformed or damaged when subjected to forces from the baffle 6 and other external forces. The slot can be processed by milling technology to ensure the flatness and dimensional accuracy of its internal surface so that it can fit closely with the baffle 6.

[0066] The baffle 6 is clamped in the slot and connected to a secondary ear plate 3 adjacent to the slot. The main function of the baffle 6 is to protect the slot, prevent debris from entering the slot and affecting the normal operation of the pin shaft 4, and also provide additional stability for the entire pin hinge structure. During the installation of the baffle 6, the shape of the baffle 6 is first precisely processed to perfectly match the shape of the slot, and then embedded in the slot, and then connected to the adjacent secondary ear plate 3 by bolt connection, using high-strength anti-loosening bolts to prevent the baffle 6 from loosening during use.

[0067] In order to further improve the service life of the pin and the safety of the structure, a first bushing 22 and a second bushing are respectively arranged in the first perforation and the second perforation, and the pin is inserted into the bushing to avoid direct contact between the pin and the inner wall of the first perforation and the second perforation, thereby effectively improving the stress condition of the pin; the first bushing 22 and the second bushing are made of graphite copper alloy. This material has good friction reduction performance and high strength, can effectively reduce the friction between the pin and the ear plate, reduce the degree of wear, and extend the service life of the structure. According to formula (1), the thickness of the bushing is accurately calculated to ensure that the bushing can fully play its role under complex stress environment, evenly disperse the force on the pin, effectively alleviate the eccentric stress and local stress concentration problems, and ensure the long-term safe and stable operation of the bridge structure.

[0068] Since no large movable bearing is required and the pier body size is reduced, the pin hinge structure of the present invention makes more efficient use of the high-strength material of the steel pier. In traditional bridge structures, in order to meet the space and force requirements of the movable bearing, a large amount of high-strength material is used in the steel pier, and the material in some areas may not fully exert its bearing capacity. In the present invention, through the reasonable layout and precise design of the main ear plate 2, the secondary ear plate 3 and the pin shaft 4, the material can be more reasonably distributed according to its force characteristics when bearing the load. For example, in the structural mechanics analysis, the bridge structure is modeled and analyzed by finite element software, and it is found that the pin hinge structure of the present invention can make the stress distribution of the bridge structure more reasonable, fully utilize the strength of the material, and greatly improve the material waste phenomenon that may exist due to the influence of the movable bearing. In an actual bridge project, after using the pin hinge structure of the present invention, through material performance testing and stress monitoring, it is found that the material utilization rate of the steel pier is increased by about 25%. This means that under the same bridge load requirements, the amount of steel pier material required can be reduced accordingly, which not only saves resources, but also reduces the deadweight of the structure, thereby reducing the burden on the foundation.

[0069] In a specific example, a large-span cable-stayed bridge across a river is constructed, and the flexible steel pier part of the bridge adopts the bridge flexible steel pier hidden support-free pin hinge structure of the present invention.

[0070] First, according to the overall design of the bridge and the calculation of structural mechanics, the main ear plate 2 is customized. The main ear plate 2 is made of high-strength alloy steel with a yield strength of 450MPa. The installation position of its lower part in the steel pier 1 is accurately measured and marked, and it is firmly welded in the steel pier 1 using submerged arc welding technology. After welding, X-ray flaw detection is carried out to ensure that the welding quality reaches the second-level standard or above. The upper part of the main ear plate 2 extends to the inner side of the box of the main beam 7. The long axis length of the first perforation 21 is 250mm and the short axis length is 210mm. The first perforation 21 is processed using a high-precision CNC machining center to ensure the accuracy of its elliptical shape.

[0071] A pair of secondary ear plates 3 are also made of high-strength alloy structural steel, and their bottoms are welded to the bottom plate of the main beam 7 by Y-shaped welds, and the weld quality grade is Grade I. The diameter of the second through hole 31 is 180 mm, and it is processed by boring equipment to ensure its roundness and cylindricity, and its relative position with the first through hole 21 of the main ear plate 2 is accurate, ensuring that the pin 4 can pass smoothly.

[0072] The pin 4 is made of specially treated high-strength alloy structural steel with a diameter of 180 mm. The surface is ground and polished to a surface roughness of Ra0.8 μm. During installation, a dedicated lifting device is used to sequentially pass the pin 4 through the second through hole 31 of the secondary ear plate 3, the first through hole 21 of the main ear plate 2, and the second through hole 31 of another secondary ear plate 3 in the transverse direction to ensure a smooth installation process and avoid damage to the through holes and the pin 4. The slot is milled to ensure the accuracy of its internal shape and size. The baffle 6 is precisely machined and embedded in the slot, and the baffle 6 is connected to the adjacent secondary ear plate 3 by bolt connection.

[0073] After the cable-stayed bridge was built and put into use, through long-term monitoring and data analysis, it was found that:

[0074] When the bridge is subjected to vehicle loads, temperature changes and wind forces, the main beam 7 will produce a certain longitudinal displacement. However, due to the cooperation between the elliptical first perforation 21 of the main ear plate 2 and the pin 4, it can adapt well to this displacement, and there will be no structural damage or abnormal stress concentration caused by limited structural deformation.

[0075] Material stress monitoring of the steel piers shows that, compared with the pier structure dimensions of traditional bearings, the stress of the optimized steel pier dimensions is also within the specification requirements, indicating that the material utilization is more reasonable and the utilization efficiency of the high-strength materials of the steel piers has been significantly improved.

[0076] Compared with the traditional flexible pier structure with movable supports, the size of the flexible pier body of this bridge is significantly reduced, saving a large amount of steel. During the construction process, it can reduce the workload of transportation, lifting and painting, reduce the construction difficulty, and reduce the overall construction cost by about 20%.

[0077] In the subsequent operation and maintenance process, it is only necessary to regularly check the various components of the pin hinge structure, such as checking whether there are cracks in the welding parts of the main ear plate 2 and the secondary ear plate 3, the wear of the pin shaft 4, and whether the baffle 6 is loose, and perform simple lubrication and tightening operations. The annual maintenance cost can be reduced by 5,000 yuan, which is much lower than the maintenance cost of the traditional structure, reflecting the economic advantage of the present invention.

[0078] The hidden support-free pin hinge structure of the flexible steel pier of the bridge of the present invention provides an innovative solution with many advantages for the design and construction of flexible steel piers of the bridge. Through unique structural design and reasonable material utilization, it solves traditional structural problems while bringing significant economic and social benefits.

[0079] In another technical solution, the bridge flexible steel pier hidden support-free pin hinge structure further includes:

[0080] The steel plate 11 is arranged on the top of the pier. The steel plate 11 is an arc-shaped structure that bends downward. The thickness of the steel plate is preferably 100 mm.

[0081] The graphite copper lining 12 is arranged on the top of the steel plate 11, and the thickness of the graphite copper lining is preferably 6 mm.

[0082] The steel plate 11 is made of high-strength steel with excellent mechanical properties. In order to meet the force requirements and bearing capacity of the bridge structure at the pier top, its thickness is preferably 100mm. In the actual manufacturing process, the processing of the steel plate 11 needs to go through multiple processes to ensure its quality and performance. First, through a precise cutting process, a CNC flame cutting machine or a laser cutting machine is used to cut the steel plate 11 from the original steel plate material. The cutting process must ensure dimensional accuracy and the error is controlled within ±1mm to ensure its adaptability to the pier top. Subsequently, the steel plate 11 is cold-bent to form a downward curved structure. During the cold bending process, professional cold bending equipment is used, and the bending radius and bending angle are strictly controlled so that the formed arc structure meets the design requirements. The design of the arc structure is not arbitrary, but is obtained through precise structural mechanics analysis. Considering the stress conditions of the bridge under different working conditions, especially under the action of vertical loads and horizontal displacements, the arc structure can better disperse stress and avoid stress concentration.

[0083] The installation of the steel plate 11 on the pier top is very important. Before installation, the surface of the pier top needs to be processed to ensure that it is flat and clean, so as to ensure a good fit between the steel plate 11 and the pier top. The steel plate 11 can be firmly fixed on the pier top by epoxy mortar or high-strength grouting material to ensure that the steel plate 11 will not loosen or shift during long-term use. At the same time, in order to prevent corrosion of the steel plate 11, an anti-corrosion treatment can be performed on its surface, such as applying anti-corrosion paint or using hot-dip galvanizing process to improve its durability.

[0084] On this basis, a graphite copper lining 12 is provided, which is located on the top of the steel plate 11. The thickness of the graphite copper lining 12 is preferably 6 mm, and is made of high-quality graphite copper alloy material. The selection of this material is based on its good friction performance and load-bearing capacity, and it also has certain self-lubricating properties, which can effectively reduce the friction between components. When manufacturing the graphite copper lining 12, a precise casting process is used to ensure its thickness uniformity, the thickness deviation is controlled within ±0.5 mm, and the surface flatness is high, and the surface roughness reaches Ra1.6μm or less, so as to ensure good contact and sliding performance between it and the steel plate 11 and other contact parts.

[0085] During the installation of the graphite copper lining 12 and the steel plate 11, a special adhesive or mechanical fixing method is used to connect them together to ensure that the connection between the two is firm and reliable. The selection of the adhesive should take into account its bonding strength and durability, and it should be able to withstand various forces during the use of the bridge. The graphite copper lining 12 and the steel plate 11 are both reserved with through holes for the upper part of the main ear plate to pass through.

[0086] The 6mm thick open arc-shaped graphite copper lining (i.e., graphite copper lining 12) provided at the top plate position of the pier top of the present invention has many significant beneficial effects. First, the arc shape of the arc-shaped graphite copper lining is conducive to the rotation of the structure, because when the bridge structure is subjected to load and deformed, its arc-shaped structure can well adapt to the rotation requirements of the structure. Under normal use, when the bridge is subjected to vertical force, the structure can effectively transfer the vertical force from the upper structure to the lower structure, and through the synergistic effect of the steel plate 11 and the graphite copper lining 12, the vertical force is evenly dispersed to the pier top and the lower part, avoiding structural damage caused by excessive local force. At the same time, the characteristics of the steel plate 11 and the graphite copper lining 12 of the arc structure ensure the release of horizontal displacement. When the bridge produces horizontal displacement due to temperature changes, vehicle loads or other factors, the graphite copper lining 12 can provide a certain sliding interface, so that the horizontal displacement can be released smoothly without excessive constraints on the structure, thereby ensuring the stability and safety of the structure.

[0087] Especially in large displacement conditions such as earthquakes, the structure demonstrates its excellent performance. Due to its unique arc shape and material properties, it can effectively transmit horizontal forces. Under the action of an earthquake, the bridge will produce a large horizontal displacement. The graphite copper lining 12 will effectively transmit the horizontal force to the pier and foundation through the interaction with the steel plate 11 and other components, avoiding structural damage caused by the inability to effectively transmit the horizontal force. This feature greatly improves the seismic performance of the structure, ensuring that the bridge remains relatively stable in extreme catastrophic events such as earthquakes, and reducing safety hazards caused by structural damage.

[0088] Moreover, under extreme working conditions, this structure can realize the function of tension and compression bearings. When the bridge structure is subjected to tensile or compressive loads, the combination of graphite copper lining 12 and steel plate 11 can act like a tension and compression bearing through its unique structure and interaction, bearing tensile stress and compressive stress. Under tensile conditions, the graphite copper lining 12 and the steel plate 11 can prevent excessive separation of the structure and ensure the integrity of the structure; under compressive conditions, they can evenly disperse the pressure and avoid local compressive damage. For example, when strong winds or extreme traffic loads cause tensile or compressive deformation of the bridge structure, the combined structure can effectively buffer and withstand these tensile and compressive stresses to ensure the normal use of the bridge. Through actual structural mechanics simulation and earthquake simulation analysis, it is found that after adopting this structure, the displacement response of the bridge is effectively controlled under the input of seismic waves, and the maximum deformation of the structure is reduced by about 20% compared with the traditional structure. When subjected to tensile and compressive loads, the stress peak of the structure is also reduced by about 15%, showing good structural performance and seismic resistance, providing a strong guarantee for the safe operation of the bridge under various complex working conditions.

[0089] In actual bridge construction, the application of this structure has brought significant advantages. In a construction example of a large-span bridge, after the steel plate 11 structure with graphite copper lining 12 was used on the pier top, it was found through long-term operation monitoring that the pier top structure always remained in good condition after daily use and after experiencing multiple earthquakes and extreme weather events, and there was no structural damage or failure caused by vertical force, horizontal displacement or tensile and compressive stress. This not only extended the service life of the pier top structure, but also reduced maintenance costs and potential safety risks, fully demonstrating the important value of this structure in ensuring bridge structural performance and improving safety.

[0090] In another technical solution, the bridge flexible steel pier has a hidden support-free pin hinge structure, and a plurality of adaptive adjustment blocks are arranged on the inner wall of the first bushing 22 and the second bushing at intervals, and the adaptive adjustment blocks are shape memory alloys with wedge-shaped structures. The outer surface of the first bushing 22 / the second bushing is finely processed, and the roughness reaches Ra1.0-Ra1.6μm to ensure good cooperation with the inner wall of the perforation; the inner surface is specially polished to further reduce the friction coefficient (Ra0.7-Ra1.0μm). The adaptive adjustment blocks are evenly distributed on the inner side wall of the bushing in the circumferential direction. The number of adjustment blocks is determined according to the size and use requirements of the bushing, generally 6-12. The adaptive adjustment blocks are made of nickel-titanium alloy (Ni-Ti) with shape memory properties. Nickel-titanium alloy has a unique shape memory effect and superelasticity, can remember its original shape within a certain temperature range, and can return to its original shape at a specific temperature after being deformed by external force. In addition, nickel-titanium alloy also has good corrosion resistance and biocompatibility, and can adapt to the complex environment in which the bridge is located.

[0091] The adjustment block is designed in a wedge shape, which can effectively convert the expansion and contraction of the adjustment block into changes in the inner diameter of the bushing. The wedge design allows the adjustment block to apply greater pressure to the inner diameter of the bushing when expanding, thereby reducing the inner diameter; when contracting, it can smoothly move in the opposite direction to increase the inner diameter.

[0092] Size determination: The thickness of the small end of the adjustment block is 2-3mm, the thickness of the large end is 5-8mm, and the length is generally 1 / 3-1 / 2 of the bushing length. Width: The width of the adjustment block is determined according to the spacing between adjacent adjustment blocks, ensuring that there is an appropriate gap between the adjustment blocks so that they can expand and contract freely during the adjustment process. The size of the gap is generally 1-2mm, which can not only ensure the free movement of the adjustment block, but also prevent the adjustment blocks from squeezing each other when expanding, causing damage.

[0093] Working principle: Temperature rise: When the ambient temperature rises, the nickel-titanium alloy adjustment block will expand thermally. Since the adjustment block is wedge-shaped, its expansion will reduce the inner diameter of the bushing. This ensures that the appropriate fit clearance is always maintained between the pin and the bushing to avoid increased friction and increased wear due to too small a clearance. When the ambient temperature drops, the nickel-titanium alloy adjustment block will shrink. Also due to the wedge-shaped design, the shrinkage of the adjustment block will increase the inner diameter of the bushing. This can avoid over-tight fit due to the shrinkage of the pin, prevent the pin from getting stuck in the bushing, and ensure the normal operation of the pin hinge structure.

[0094] In another technical solution, the flexible steel pier of the bridge has a hidden support-free pin hinge structure, in which the upper part of the main ear plate 2 is provided with a first reinforcing plate 23 on both sides along the lateral direction, and the lower part of the main ear plate 2 is provided with stiffening ribs 24 on both sides along the lateral direction; each secondary ear plate 3 is provided with a second reinforcing plate 32 on both sides along the lateral direction.

[0095] The first reinforcing plate 23 is located on both sides of the upper part of the main ear plate 2 in the lateral direction. It is made of high-strength steel plate, and the thickness can be determined according to the specific stress conditions. The first reinforcing plate is provided with a through hole corresponding to the first perforation to allow the pin to pass through. When installing the first reinforcing plate 23, it is necessary to first ensure its fit with the main ear plate 2. Use precise cutting and processing technology to ensure that the length of the first reinforcing plate 23 matches the lateral length of the main ear plate 2, and the error is controlled within ±2mm. The first reinforcing plate 23 is connected to the main ear plate 2 by welding. The welding quality must be strictly controlled during the welding process. Multi-layer and multi-pass welding is used to ensure the strength and quality of the weld. After welding is completed, the weld is inspected using non-destructive testing technology (such as ultrasonic testing) to ensure the integrity and reliability of the weld and avoid welding defects such as pores and cracks.

[0096] The stiffening ribs 24 are arranged on both sides of the lower part of the main ear plate 2 in the horizontal direction and are located inside the steel pier. The main function of the stiffening ribs 24 is to enhance the local stability and disperse the gravity of the lower part of the main ear plate 2 to prevent local instability and damage when bearing a large load. The stiffening ribs 24 can be in the form of plate ribs, extending to the bridge pier and welded thereto. The connection between the stiffening ribs 24 and the main ear plate 2 is also welded. In order to ensure a firm connection, the connection parts should be pretreated before welding to remove oxide scale and oil stains, and appropriate welding parameters should be used during the welding process to ensure that the stiffening ribs 24 can effectively disperse the load, prevent local instability of the main ear plate 2, and improve the stability of the main ear plate. For the reinforcement of the secondary ear plate 3, each secondary ear plate 3 is provided with a second reinforcement plate 32 on both sides in the horizontal direction. Similarly, the second reinforcement plate is also provided with a through hole for the pin shaft to pass through. The baffle is connected to one of the adjacent second reinforcement plates, and the connection method is bolt connection (bolt holes are provided on the baffle, and bolt grooves are provided on the outer side of the second reinforcement plate, and the bolts are inserted into the bolt holes and extend into the grooves).

[0097] The second reinforcing plate 32 is also made of high-strength steel plate, and its length is determined according to the size of the secondary ear plate 3, and it fits closely with the secondary ear plate 3. The connection of the second reinforcing plate 32 is also completed by welding. During welding, it is necessary to ensure that the weld is uniform to avoid local stress concentration. A combination of intermittent welding and continuous welding can be used. The length of the intermittent welding is 50 mm and the spacing is 100 mm, so as to ensure that the deformation and residual stress caused by excessive welding are avoided while meeting the strength requirements.

[0098] By setting reinforcing plates and stiffening ribs, the hidden support-free pin hinge structure of the flexible steel pier of the entire bridge is brought about a significant beneficial effect, namely, improving the strength and stability of the overall structure.

[0099] First, during the daily operation of the bridge, it will be subjected to various loads, including vehicle loads, wind loads, and internal forces caused by temperature changes. As an important load-bearing component, the main ear plate 2 is prone to stress concentration when bearing these loads, especially at the connection parts with other components and areas with greater stress. The setting of the first reinforcing plate 23 and the stiffening rib 24 effectively solves this problem. The first reinforcing plate 23 can improve the bearing capacity of the upper part of the main ear plate 2. When the main beam 7 transfers the load to the main ear plate 2, the first reinforcing plate 23 can disperse part of the stress to a larger area to prevent the main ear plate 2 from being damaged. For example, when performing finite element analysis on the bridge, by comparing the models with and without the first reinforcing plate 23, the main ear plate 2 with the first reinforcing plate 23 has a maximum stress value reduced by about 30% under the same load, which significantly improves the bearing capacity and stability of the upper part of the main ear plate 2.

[0100] The stiffening ribs 24 mainly enhance the local stability and shear resistance of the lower part of the main lug plate 2. When the pier is subjected to a large vertical load, the stiffening ribs 24 can effectively share the stress caused by the vertical load, avoiding local instability or damage of the lower part of the main lug plate 2 due to the large stress. At the same time, the stiffening ribs 24 can also share the shear stress caused by the horizontal load at the lower part of the main lug plate 2. In the actual structural test, when vertical pressure is applied to the main lug plate 2 with the stiffening ribs 24, the stiffening ribs 24 effectively transmit the pressure, making the stress distribution of the main lug plate 2 more uniform, and improving the local stability and shear safety reserve of the main lug plate 2.

[0101] For the secondary ear plate 3, the second reinforcing plate 32 is provided to enhance the local stability of the secondary ear plate 3. During the driving process of the vehicle, the secondary ear plate 3 and the bottom plate of the main beam 7 are subjected to stress at the same time, and the second reinforcing plate 32 can improve the local stability and bearing capacity of the secondary ear plate 3. By arranging the second reinforcing plates 32 on both sides of the secondary ear plate 3, stress concentration is avoided. Under the same lateral load, the maximum stress of the secondary ear plate 3 with the second reinforcing plates 32 is reduced by about 40%, ensuring the local stability and strength of the secondary ear plate 3 when subjected to stress.

[0102] In an actual large-span bridge project, this pin-hinge structure with reinforcement plates and stiffening ribs was used. After long-term use and multiple tests of extreme loads (such as strong winds and the passage of overweight vehicles), through stress and deformation monitoring of the structure, it was found that the structural integrity of the entire pin-hinge structure was well maintained, the connections between the components were firm, and there was no structural damage or excessive deformation due to insufficient local strength. It demonstrated excellent strength and stability, thereby ensuring the safe operation of the bridge and reducing the maintenance and reinforcement costs caused by structural damage.

[0103] In another technical solution, the bridge flexible steel pier hidden support-free pin hinge structure further includes:

[0104] A plurality of first impact force sensors are embedded in the upper portion of the main ear plate 2 at intervals, and the first impact force sensors are used to monitor the impact force received by the main ear plate 2;

[0105] A plurality of second impact force sensors are embedded in the pin shaft 4 at intervals along the axial direction of the pin shaft 4, and the second impact force sensors monitor the impact force received by the pin shaft 4;

[0106] A plurality of temperature sensors are arranged on the pin shaft 4 at intervals along the axial direction of the pin shaft 4, and the temperature sensors are used to monitor the working temperature of the pin shaft 4 in real time;

[0107] A locking mechanism, which is provided on the first reinforcing plate 23 and is used to lock the pin 4;

[0108] A controller is connected to multiple first impact force sensors, multiple second impact force sensors, a temperature sensor, and a locking mechanism; the controller is configured to collect a first detection value of the first impact force sensor, a second detection value of the second impact force sensor, and a third detection value of the temperature sensor, the controller inputs the first detection value, the second detection value, and the third detection value into a pre-constructed connection structure risk prediction model, and outputs a risk warning level of the connection structure. When the risk warning level reaches a preset high-risk threshold, the controller sends an alarm signal and simultaneously starts the locking mechanism to lock the pin shaft 4.

[0109] A plurality of first impact force sensors are embedded in the upper part of the main ear plate 2 at intervals. When installing the first impact force sensor, firstly, it is necessary to reserve corresponding mounting holes in the upper part of the main ear plate 2. The positions and sizes of these mounting holes are precisely processed according to the external dimensions and installation requirements of the first impact force sensor, ensuring that the diameter of the mounting hole is 1-2 mm larger than the outer diameter of the sensor to facilitate the embedded installation of the sensor, and at the same time ensuring that the depth of the mounting hole meets the embedded depth requirement of the sensor. The sensor can be embedded by epoxy resin bonding or mechanical fixing to ensure that the sensor is firmly fixed in the main ear plate 2 and ensure good force transmission performance between the sensor and the main ear plate 2. Each first impact force sensor has high sensitivity and accuracy. These sensors can sense the impact force of the main ear plate 2 in real time under different working conditions, such as vehicle collision, foreign object impact or other unexpected impact, and provide key data for subsequent structural health assessment.

[0110] A plurality of second impact force sensors are embedded in the pin 4 at intervals along the axial direction of the pin 4. When manufacturing the pin 4, it is necessary to reserve installation space for the second impact force sensor. The dimensional accuracy of these spaces is required to be high, and the dimensional tolerance of the installation space is guaranteed to be within ±0.1mm through precision machining. The second impact force sensor adopts a special micro sensor that can withstand a large impact force without affecting the strength and performance of the pin 4. Its installation process involves complex processes, such as first installing the sensor into a pre-processed installation groove, and then fixing it with special sealants or filling materials to ensure its sealing and stability, and prevent the performance of the sensor from being affected by the entry of liquids or debris during use. These sensors can accurately measure the impact force along the axial direction of the pin 4. By being arranged at different axial positions of the pin 4, they can fully monitor the impact force received by the pin 4 during the use of the bridge, and provide detailed data for evaluating the stress state of the pin 4.

[0111] The first impact force sensor and the second impact force sensor are preferably piezoelectric impact force sensors with a range of 0-1000 kN and an accuracy of ±1% FS. The sensor outputs the measured data in the form of an analog signal, which is converted into a digital signal by an analog-to-digital converter (ADC) for analysis by the microprocessor.

[0112] A plurality of temperature sensors are arranged on the pin 4 at intervals along the axial direction of the pin 4 to monitor the working temperature of the pin 4 in real time. The temperature sensor adopts a high-precision thermocouple or thermistor sensor with an accuracy of up to ±0.5°C. During installation, the temperature sensor is firmly fixed to the surface of the pin 4 by a special mounting fixture to ensure good thermal conductivity with the pin 4. At the same time, in order to avoid interference with the temperature measurement by the external environment, the sensor is protected, such as wrapping it with a heat-insulating and protective sleeve so that it can accurately reflect the actual working temperature of the pin 4. Temperature monitoring is crucial for evaluating the working state of the pin 4, because temperature changes may affect the mechanical properties of the pin 4 and its surrounding components. Real-time monitoring of temperature can provide important environmental parameters for the safety assessment of the structure.

[0113] The locking mechanism is arranged on the first reinforcing plate 23, and its design and installation shall satisfy the function of reliably locking the pin 4 when necessary. The locking mechanism may be driven by hydraulic or electric means. For example, when a hydraulic locking mechanism is used, it includes a hydraulic cylinder, an oil circuit system and a locking component. The cylinder body of the hydraulic cylinder is firmly mounted on the first reinforcing plate 23, and its position is ensured to be accurate through precise positioning and bolt connection. The oil circuit system includes an oil pump, an oil pipe and a control valve, which can provide the required hydraulic power for the hydraulic cylinder to ensure the reliability of its action. The locking component is in direct contact with the pin 4, and its shape and size are customized according to the shape of the pin 4, for example, it can be an embracing lock buckle or a latch-type structure. In the locked state, the locking component can firmly hold or insert the pin 4 to prevent it from moving in the corresponding direction. At the same time, in order to ensure the reliability and durability of the locking mechanism, its key components are made of high-strength alloy steel and undergo special surface treatment, such as nitriding, to improve its wear resistance and corrosion resistance.

[0114] The controller is connected to multiple first impact force sensors, multiple second impact force sensors, temperature sensors, and locking mechanisms. The controller is a highly integrated intelligent control unit with powerful data acquisition, processing and analysis capabilities. It uses advanced microprocessor chips, such as ARM architecture processors, with high computing speed and low power consumption. The controller communicates with each sensor through a dedicated cable. The cable uses a shielded cable to reduce the impact of electromagnetic interference on signal transmission. Multiple data acquisition channels are set in the controller, corresponding to different sensors, to ensure that the first detection value of the first impact force sensor, the second detection value of the second impact force sensor, and the third detection value of the temperature sensor can be collected simultaneously.

[0115] The controller includes:

[0116] Microprocessor: ARM Cortex-M4 microprocessor is preferred, which has powerful data processing capabilities and low power consumption. The microprocessor is responsible for receiving and monitoring data, and judging whether the locking operation needs to be triggered according to the preset program logic.

[0117] Communication module: It uses a 4G wireless communication module, which can communicate remotely with the server of the bridge management center. When a lock or unlock instruction is received, or when the device status information needs to be sent to the management center, data is transmitted through the 4G network.

[0118] Power module: Powered by a lithium battery pack with a battery capacity of 5000mAh, it is also equipped with a power management chip to manage the battery charging and discharging process to ensure stable power supply under different working conditions. When the battery power is less than 20%, the microprocessor will send a low power alarm message to the bridge management center.

[0119] The controller inputs the collected data into a pre-built risk prediction model for the connection structure, which is developed based on a large amount of experimental data and actual bridge operation data, using big data analysis and artificial intelligence algorithms. When building the model, sensor data from many bridges under different working conditions (including normal operation, different degrees of vehicle loads, various meteorological conditions, and extreme conditions such as earthquakes) were collected as sample sets, and the sample sets were trained using a deep learning algorithm. The input of the model includes multi-dimensional information such as impact force data and temperature data, and the output is the risk warning level of the connection structure. During operation, the controller continuously analyzes and processes the data, and accurately determines the health status of the connection structure based on the preset algorithm and model parameters.

[0120] The present invention has significant beneficial effects. Based on big data analysis and artificial intelligence algorithms, the collected data is processed and analyzed to achieve intelligent evaluation of the health status of the connection structure. In the daily operation and maintenance of the bridge, various sensors continuously collect data, and these data are gathered together through the controller to form a rich data set. Using big data analysis technology, the system can conduct a comprehensive analysis of historical data and real-time data, explore the potential laws in the data, and find out the trends of structural stress, deformation and temperature changes under different working conditions. At the same time, the artificial intelligence algorithm can perform in-depth mining and learning based on these data, and continuously optimize the connection structure risk prediction model, so that the model can more accurately assess the risk status of the structure.

[0121] When the impact force between the pin and the main lug plate is too large under abnormal conditions such as earthquakes, the system automatically triggers the early warning mechanism and starts the adaptive pin locking device according to the preset control strategy. The device can be set at the main lug reinforcement plate or the main lug opening position. Its main function is to lock and fix the pin when the impact force of the earthquake condition exceeds the early warning value, so that it no longer moves and forms a whole with the main lug plate, thereby transforming the flexible pier into a rigid pier, which is beneficial to the overall seismic performance of the bridge. When an earthquake occurs, the bridge structure will be subjected to a huge impact force, which may cause an abnormally large impact force between the main lug plate 2 and the pin 4. At this time, the first impact force sensor and the second impact force sensor can quickly detect the change of the impact force and transmit the data to the controller. Once the controller determines that the impact force exceeds the preset high-risk threshold according to the risk prediction model, it will immediately send an alarm signal and start the locking mechanism at the same time. The locking mechanism will act quickly, for example, the hydraulic cylinder in the hydraulic locking mechanism will push the locking component to firmly lock the pin 4, so that it will instantly change from a flexible connection state to a rigid connection state.

[0122] This adaptive locking mechanism provides an important safety guarantee for the bridge under earthquake conditions. When the pin 4 is locked, the flexible pier is transformed into a rigid pier, providing a temporary rigid connection, so that all bridge piers share the sudden external excitation loads such as earthquakes, enhance the overall stiffness of the bridge, so that it can withstand greater earthquake forces and avoid structural damage caused by excessive deformation. In actual earthquake simulation tests and actual earthquake monitoring, when the system starts the locking function, the stability and safety of the bridge in earthquakes are greatly improved. At the same time, through this intelligent monitoring and early warning mechanism, it can not only play a role in earthquakes, but also timely discover potential risks of the structure in daily operations, such as structural abnormalities caused by long-term use or local damage, provide a scientific basis for the daily maintenance and repair of the bridge, extend the service life of the bridge, and reduce maintenance costs. For example, through long-term monitoring and analysis of sensor data, fatigue damage or other hidden dangers that may occur in the main ear plate 2 or the pin 4 can be discovered in advance, and preventive maintenance measures can be taken before the failure occurs, avoiding major accidents and high maintenance costs caused by structural damage.

[0123] The construction method of the connection structure risk prediction model is as follows:

[0124] Collect the first detection value, second detection value, third detection value and corresponding known risk warning level of the hidden support-free pin hinge structure of the flexible steel pier of the bridge in the actual operation in history, and form a historical data sample;

[0125] The historical data samples are divided into a training set and a validation set in a ratio of 7:3. The first detection value, the second detection value, and the third detection value in the training set are used as input values, and the risk warning level is used as the output value to train the random forest model. The random forest model is trained by continuously adjusting the parameters of the model (such as the number of trees, the maximum depth, etc.);

[0126] The trained and optimized model is verified using the validation set data, and the optimized random forest model obtained is the connection structure risk prediction model (the generalization ability and prediction accuracy of the model are judged by calculating the accuracy, recall rate, F1 value and other evaluation indicators of the model on the validation set. If the performance of the model on the validation set does not meet expectations, the model parameters are readjusted and trained until the model performance meets the requirements).

[0127] 1. Data collection stage:

[0128] First, a large amount of data collection work is required to collect the first, second, and third test values ​​of the bridge flexible steel pier hidden support-free pin hinge structure in actual historical operation, as well as the corresponding known risk warning levels, to form a historical data sample. The source of these data can be multiple bridge projects that have been built and put into use, covering different geographical environments, traffic flows, service life and climatic conditions, etc., to ensure the diversity and representativeness of the samples. Or it can be data obtained from laboratory simulation experiments.

[0129] Collection of the first detection value: The first detection value mainly comes from a plurality of first impact force sensors, which are distributed in the upper part of the main ear plate 2 and can monitor the impact force received by the main ear plate 2. In different bridge operation scenarios, the sensors are used to collect the impact force data received by the main ear plate 2 in real time under vehicle driving, wind load impact, earthquake and other working conditions. The measurement range can range from the micro-impact force generated by very small daily traffic to the larger impact force in extreme cases, such as from 0kN to 500kN. The data are collected at a high frequency, for example, once every 0.1 seconds, to ensure that the instantaneous impact force peak can be captured, providing sufficient data density for subsequent analysis.

[0130] Collection of the second detection value: The second detection value is obtained by a plurality of second impact force sensors embedded in the pin 4 at intervals along the axial direction of the pin 4, reflecting the impact force on the pin 4. Since the pin 4 is subjected to impacts from different directions and with different intensities in the bridge structure, its data collection range may be different from the first detection value, for example, from 0kN to 300kN, and the collection frequency is also maintained at a high level to accurately record the stress state of the pin 4 under various working conditions.

[0131] Collection of the third detection value: The third detection value is provided by a plurality of temperature sensors arranged on the pin 4 at intervals along the axial direction of the pin 4, and is used to monitor the working temperature of the pin 4 in real time. The temperature data may range from the lowest ambient temperature (e.g. -30°C) to the highest ambient temperature (e.g. 50°C) in the area where the bridge is located. At the same time, considering the temperature rise caused by friction, internal structural stress and other factors, data of local temperatures as high as 100°C or above may be recorded. The frequency of temperature data collection can be adjusted according to the rate of temperature change, generally once every 1 minute, but when the temperature changes rapidly, the collection frequency can be increased to once every 10 seconds.

[0132] Determination of known risk warning levels: The known risk warning levels are based on the actual operating conditions of historical bridge structures and are divided into different levels according to the degree of damage, maintenance records and safety conditions of the structure, such as low risk, medium risk and high risk levels. A low risk level may mean that the structure is basically normal and only requires routine inspection and maintenance; a medium risk level may mean that the structure has some minor damage or performance degradation, but it does not affect normal use; a high risk level means that the structure is already in a more dangerous state and immediate repair or reinforcement measures are required. These risk warning levels are obtained through comprehensive judgments such as regular inspections of bridge structures, non-destructive testing (such as ultrasonic testing, magnetic particle testing), structural deformation measurements, and historical maintenance records.

[0133] 2. Data division stage:

[0134] The collected historical data samples are divided into a training set and a validation set in a ratio of 7:3. This division is to ensure the scientificity and effectiveness of model training and validation and avoid overfitting. In the division process, random sampling is used to ensure that the data distribution in the training set and validation set is representative and does not cause data deviation due to human factors.

[0135] Formation of training set: About 70% of the data are selected as the training set. These data will serve as the basis for model learning. They contain rich structural stress and temperature information as well as corresponding risk warning levels, and are the core data source for training the random forest model.

[0136] Formation of the validation set: The remaining 30% of the data is used as a validation set, which is mainly used to evaluate the trained model and verify its performance on data that has not participated in the training, so as to judge the generalization ability and prediction accuracy of the model.

[0137] 3. Model training stage:

[0138] The first, second and third detection values ​​in the training set are used as input values, and the risk warning level is used as the output value to train the random forest model. Random forest is a machine learning algorithm based on decision tree ensemble. It constructs multiple decision trees and lets them perform classification or regression prediction on the data, and finally integrates the results of multiple decision trees to obtain the final prediction result.

[0139] Parameter adjustment: During the training process, the model parameters (such as the number of trees, maximum depth, etc.) are continuously adjusted to optimize the model's performance. The number of trees will affect the complexity and predictive power of the model. It can be initially set to 100 trees and then adjusted based on the training effect; the maximum depth determines the depth of the decision tree, which can range from 5 to 20. Too deep a tree may lead to overfitting, while too shallow a tree may cause insufficient model performance. When adjusting parameters, use grid search, random search, or experience-based adjustment methods to determine the best parameter combination based on the model's performance indicators on the training set (such as mean square error, accuracy, etc.). For example, first perform a grid search between 50 and 200 trees, adjust the maximum depth between 3 and 25, and observe the performance of the model under different parameter combinations.

[0140] Training process: After each parameter adjustment, the random forest model is trained using the data from the training set. For each decision tree, a portion of samples (usually two-thirds of the total samples) are randomly selected from the training set for training, while allowing each decision tree to have a certain degree of randomness so that they can learn different characteristics of the data and enhance the robustness of the model. During the training process, based on the input first detection value, second detection value, and third detection value, the model will learn how to map these inputs to the corresponding risk warning level, and improve the model's classification or regression capabilities for different input combinations by continuously iterating and optimizing decision rules.

[0141] 4. Model verification and optimization stage:

[0142] The trained and optimized model is verified using the validation set data, and the optimized random forest model obtained is the connection structure risk prediction model.

[0143] Performance evaluation: By calculating the accuracy, recall, F1 value and other evaluation indicators of the model on the validation set, the generalization ability and prediction accuracy of the model can be judged. The accuracy rate indicates the proportion of samples correctly predicted by the model to the total number of samples, reflecting the overall accuracy of the model's prediction; the recall rate indicates the proportion of samples correctly predicted as positive by the model among all samples that are actually positive, reflecting the model's ability to identify positive samples; the F1 value is the harmonic mean of the accuracy and recall rate, which comprehensively reflects the performance of the model. For example, if a model has an accuracy of 85% and a recall of 80% on the validation set, the F1 value is 82.35%. These indicators can help us fully understand the performance of the model.

[0144] Model optimization: If the model's performance on the validation set does not meet expectations, readjust the model parameters and perform training until the model performance meets the requirements. During the optimization process, you may need to adjust parameters multiple times, retrain and verify, and iterate continuously. For example, if you find that the recall rate of the model is low, you may need to increase the number of trees or adjust the splitting strategy of the decision tree to better capture the characteristics of the positive samples; if the accuracy rate is low, you may need to further preprocess the data or adjust the depth of the tree to prevent overfitting. At the same time, the performance evaluation of the model is not limited to the above indicators. You can also consider using indicators such as mean square error and mean absolute error for comprehensive evaluation to ensure that the model can perform well in various situations.

[0145] In actual bridge operation and maintenance, the connection structure risk prediction model constructed in this way can continuously predict the newly collected first test value, second test value and third test value, and evaluate the risk warning level of the current bridge structure. Once the risk level is predicted to reach a high risk, corresponding maintenance and reinforcement measures can be taken in time to ensure the safety of the bridge structure.

[0146] In another technical solution, the risk warning level of the output connection structure of the hidden support-free pin hinge structure of the bridge flexible steel pier has been optimized and adjusted, specifically:

[0147] When the risk warning level is less than the preset high-risk warning value, and the ratio of the first detection value to the theoretical bearing impact force of the main ear plate is greater than 0.6, the controller calculates the change rate of the first detection value within a historical week. If the change rate of the first detection value exceeds 5%, the risk warning level is adjusted to the high-risk threshold.

[0148] In the above technical solution, if the currently acquired risk warning level value is less than the pre-set high-risk warning value, it is also necessary to examine the relationship between the first detection value (the impact force actually borne by the main ear plate) and the theoretical bearing impact force of the main ear plate. When the ratio of the first detection value to the theoretical bearing impact force of the main ear plate is greater than 0.6, the rate of change of the impact force of the main ear plate is detected. The controller not only collects the current sensor detection value, but also records the change trend of each sensor data over a period of time. For example, for the first impact force sensor and the second impact force sensor, the growth rate of the impact force over time is analyzed. When the historical change rate of the first detection value within one week is calculated, if the change rate exceeds 5%, the system will automatically adjust the current risk warning level to the high-risk threshold. Through such a series of interlocking judgments and operations, it is ensured that the system can respond appropriately to potential risks in a timely and accurate manner to ensure the stable operation and safety of the entire system.

[0149] In another technical solution, the optimization and adjustment of the risk warning level of the connection structure of the bridge flexible steel pier hidden type support-free pin hinge structure also includes:

[0150] When the risk warning level is less than the preset high risk warning value and the third detection value is greater than 50°C, the risk warning level is adjusted once for every 5°C increase in the third detection value relative to 50°C. The risk warning level after each adjustment is 1.1 times the value of the previous risk warning level.

[0151] In another risk warning level optimization scheme for the hidden support-free pin hinge structure connection structure of the bridge flexible steel pier, this application makes a more detailed setting of the risk warning level adjustment rules, aiming to more accurately reflect the potential risks of the connection structure under different working conditions. The specific contents are as follows:

[0152] When the risk warning level is less than the preset high risk warning value (assuming that the high risk threshold is 80 points, the full score is 100 points), and the third detection value of the temperature sensor is greater than 50°C, the system will dynamically adjust the risk warning level based on the temperature change. The specific adjustment method is: the risk warning level will be adjusted once for every 5°C increase in the third detection value relative to 50°C. The risk warning level after each adjustment is 1.1 times the value of the previous risk warning level.

[0153] For example, if the current risk warning level is 60 points and the third detection value is 55°C, then the risk warning level will be adjusted to 60×1.1=66 points. If the temperature further rises to 60°C, the risk warning level will be adjusted again to 66×1.1=72.6 points. In this way, the risk changes that may be brought to the connection structure due to the increase in temperature can be more keenly captured, making the risk warning mechanism more sensitive and accurate. This dynamic adjustment mechanism based on temperature changes fully considers the impact of high temperature environment on the bridge connection structure, which helps to take corresponding maintenance measures in advance to ensure the safe and stable operation of the bridge.

[0154] In another technical solution, the controller of the bridge flexible steel pier hidden support-free pin hinge structure is further configured to send a low-risk warning signal every 1 hour if the ratio of the risk warning level after optimization adjustment to the high-risk warning threshold is greater than 0.5 and less than 0.65;

[0155] If the ratio of the risk warning level after optimization and adjustment to the high risk warning threshold is greater than or equal to 0.65 and less than 1, the controller will issue a medium risk warning signal and send it every 0.3 hours;

[0156] If the ratio of the optimized and adjusted risk warning level to the high-risk warning threshold is greater than or equal to 1, the controller sends a continuous high-risk warning signal and activates the locking mechanism to lock the pin.

[0157] In another technical solution for the hidden support-free pin-hinge structure of flexible steel piers of bridges, this application makes more detailed and comprehensive optimization settings for the risk warning logic of the controller, aiming to further improve the accuracy and effectiveness of the risk warning mechanism, and ensure that the bridge connection structure can be monitored and handled in a timely and appropriate manner under various complex working conditions.

[0158] Specifically, after a series of risk warning level optimization adjustments, the controller will perform different levels of warning operations based on the ratio of the optimized risk warning level to the preset high risk warning threshold. Assuming that the preset high risk warning threshold is 80 points (out of 100 points), the following is the detailed warning logic:

[0159] Low-risk warning: If the ratio of the risk warning level after optimization and adjustment to the high-risk warning threshold is greater than 0.5 and less than 0.65, it means that although there is a certain risk in the current bridge connection structure, the overall situation is still in a relatively controllable range. At this time, the controller will issue a low-risk warning signal. In order to allow relevant maintenance personnel to continue to pay attention to this state, the controller will send this low-risk warning signal every hour. For example, if the risk warning level after optimization and adjustment is 45 points, its ratio to the high-risk warning threshold of 80 points is 45÷80=0.5625, which meets the low-risk warning conditions. At this time, the controller sends a low-risk warning message to the bridge maintenance personnel through SMS, APP push, etc., informing them that the bridge connection structure is currently in a low-risk state, but they need to keep paying attention and pay attention to the status of the main ear plate and the pin shaft in subsequent inspections.

[0160] Medium risk warning: When the ratio of the risk warning level after optimization and adjustment to the high risk warning threshold is greater than or equal to 0.65 and less than 1, it indicates that the risk level of the bridge connection structure has increased and needs to be paid more attention. In this case, the controller will issue a medium risk warning signal, and in order to timely feedback the risk dynamics, the warning signal will be sent every 0.3 hours. For example, if the risk warning level after optimization and adjustment is 68 points, its ratio to the high risk warning threshold of 80 points is 68÷80=0.85, which meets the medium risk warning conditions. At this time, in addition to sending warning information to maintenance personnel, the controller will automatically increase the monitoring frequency of each sensor from once an hour to once every 30 minutes in order to obtain more real-time and accurate data. At the same time, professional inspection personnel are arranged to conduct local non-destructive testing of the connection structure, such as using ultrasonic flaw detection, magnetic particle flaw detection and other technologies to carefully check whether there are minor damages and discover potential hidden dangers in advance.

[0161] High-risk warning: If the ratio of the risk warning level after optimization and adjustment to the high-risk warning threshold is greater than or equal to 1, it means that the bridge connection structure is facing extremely high risks, and serious accidents such as connection failure may occur at any time. At this time, the controller will issue a continuous high-risk warning signal to ensure that relevant personnel can detect the danger at the first time. At the same time, in order to prevent accidents, the controller immediately activates the locking mechanism to lock the pin to limit the structural displacement or damage that may be caused by connection failure. For example, if the risk warning level after optimization and adjustment is 85 points, its ratio to the high-risk warning threshold of 80 points is 85÷80=1.0625, which meets the high-risk warning conditions. At this time, the on-site alarm will continue to sound, reminding surrounding personnel to pay attention to safety, and the locking mechanism will act quickly to ensure the temporary stability of the bridge connection structure, waiting for further processing by professionals.

[0162] Through such detailed and accurate risk warning classification and operation settings, this technical solution can more comprehensively and flexibly respond to various risk conditions that may arise in the actual operation of the hidden support-free pin-hinge structure of the flexible steel pier of the bridge, providing a more reliable guarantee for the safe and stable operation of the bridge.

[0163] In another technical solution, the bridge flexible steel pier hidden type support-free pin hinge structure, the first reinforcing plate 23 is provided with a plurality of mounting grooves 231; the pin shaft 4 is provided with a plurality of locking holes 42, which are arranged one by one corresponding to the plurality of mounting grooves 231;

[0164] The locking mechanism includes:

[0165] A plurality of drivers 51, one driver 51 is disposed in each mounting slot 231; each driver 51 is connected to a controller;

[0166] A plurality of locking tongues 52 are provided at the output end of each driver 51 . Each driver 51 drives the locking tongue 52 to move along the radial direction of the pin shaft 4 and to be inserted into the corresponding locking hole 42 .

[0167] In the above technical solution, the position layout of the installation groove 231 needs to consider the mechanical effect of locking and the force distribution, and its distribution should be uniform and reasonable to ensure that when locking the pin shaft 4, a balanced locking force can be provided to prevent local stress concentration. For the surface treatment of the installation groove 231, in order to ensure good contact and force transmission between the driver 51 and the first reinforcing plate 23, the inner wall of the installation groove 231 needs to be polished to a surface roughness of Ra1.6μm or less, to ensure that the driver 51 will not generate additional friction or stress concentration due to surface unevenness after installation.

[0168] Processing and design of locking hole 42:

[0169] A plurality of locking holes 42 are processed on the pin shaft 4. The position and size of the locking holes 42 need to correspond to the mounting groove 231 one by one to ensure that the locking tongue 52 can be accurately inserted into the locking hole 42 to achieve the locking function. The diameter of the locking hole 42 is designed according to the outer diameter of the locking tongue 52. Generally, the diameter of the locking hole 42 is 0.5-1mm larger than the outer diameter of the locking tongue 52, so that the locking tongue 52 can be smoothly inserted and pulled out, while ensuring the reliability of the locking. The machining accuracy of the locking hole 42 is relatively high. Drilling or boring and other machining processes are used to ensure that its position accuracy is within ±0.2mm to ensure its accurate correspondence with the mounting groove 231. After the machining is completed, the interior of the locking hole 42 is cleaned and inspected to prevent iron filings or impurities generated during the machining process from remaining therein and affecting the normal insertion of the locking tongue 52.

[0170] A driver 51 is arranged in each mounting groove 231, and the driver 51 is the power source for realizing the movement of the lock tongue 52. The driver 51 can be in the form of an electric push rod, a hydraulic push rod or a pneumatic push rod, etc., and the electric push rod is used as an example for explanation here. The selection of the driver 51 needs to consider the driving force required for locking. According to the design calculation of the structure, the rated thrust of the driver 51 needs to meet the force required when the lock tongue 52 is inserted into the locking hole 42, and at the same time consider a certain safety factor, such as 1.5 times the locking force. When installing the driver 51, carefully place it in the mounting groove 231 and use bolts or other mechanical connection methods to firmly fix it in the mounting groove 231. The installation position of the driver 51 must ensure that its axial direction is consistent with the movement direction of the lock tongue 52, and its positioning accuracy is required to be within ±1mm. In order to ensure the reliability of the driver 51, its internal motor (for the electric push rod) adopts a high-efficiency, low-noise, high-torque servo motor, and its shell is made of high-strength aluminum alloy or steel material to withstand various loads and environmental factors during the working process. The driver 51 is connected to the controller via a cable. The cable routing should be planned reasonably to avoid interference with other components. Shielded cables should be used to reduce the impact of electromagnetic interference on signal transmission.

[0171] The driver 51 is also equipped with a corresponding position sensor for accurately feeding back the position information of the lock tongue 52 to ensure that the movement state of the lock tongue 52 can be accurately monitored. The position sensor can be a linear displacement sensor with a measurement accuracy of up to ±0.1 mm. By real-time monitoring of the position of the lock tongue 52, the controller can accurately determine whether the lock tongue 52 has been fully inserted into or pulled out of the locking hole 42 to prevent the lock from being in place or misoperation.

[0172] A locking tongue 52 is provided at the output end of each driver 51, and the design of the locking tongue 52 needs to meet the matching requirements and locking strength requirements of the locking hole 42. The locking tongue 52 is made of high-strength alloy steel, and its length and diameter are determined according to the depth and diameter of the locking hole 42 to ensure that the locking tongue 52 can provide sufficient shear and tensile resistance after being inserted into the locking hole 42. The front end of the locking tongue 52 adopts a conical or hemispherical guide design to facilitate better alignment when inserted into the locking hole 42, reducing resistance and wear during the insertion process. The surface of the locking tongue 52 is quenched to improve its hardness and wear resistance, and the surface hardness can reach HRC40-50.

[0173] Each driver 51 drives the locking tongue 52 to move radially along the pin shaft 4. After receiving the control signal from the controller, the driver 51 converts the rotational motion of the motor into the linear motion of the locking tongue 52 through the internal transmission mechanism (such as a screw-nut pair or a gear rack mechanism), or the driver of the hydraulic telescopic cylinder drives the locking tongue to move linearly. In the process of the driver 51 driving the locking tongue 52 to move, its speed and stroke can be adjusted according to actual needs. The controller sets the parameters of the driver 51 to control the moving speed of the locking tongue 52 within a suitable range, for example, a moving speed of 5-10 mm per second, so as to ensure that the locking tongue 52 can be smoothly and quickly inserted into or pulled out of the locking hole 42, and avoid damage to the structure caused by the impact and vibration caused by the excessive speed.

[0174] In actual operation, when the pin 4 needs to be locked, the controller sends a locking signal to the driver 51 based on the data collected by the sensor and the evaluation results of the risk prediction model of the connection structure. After receiving the signal, the driver 51 drives the lock tongue 52 to move toward the locking hole 42 along the radial direction of the pin 4, and inserts the lock tongue 52 into the corresponding locking hole 42. In this process, the position sensor feeds back the position information of the lock tongue 52 in real time to ensure that the lock tongue 52 is accurately inserted into the locking hole 42, thereby achieving reliable locking of the pin 4. Conversely, when unlocking is required (the risk warning level is reduced), the controller sends an unlocking signal, and the driver 51 drives the lock tongue 52 to retract, so that the lock tongue 52 is pulled out of the locking hole 42, and the free activity state of the pin 4 is restored, ensuring the flexibility and deformation adaptability of the bridge structure under normal working conditions.

[0175] Preferably, in the bridge flexible steel pier hidden support-free pin hinge structure, the inlet and outlet ends of the first perforation are both flared, the flaring angle is 10-20°, and the flaring length is 0.3-0.5 times the diameter of the pin. After the flaring, the pin can be inserted into the first perforation 21 more smoothly, effectively avoiding the pin from easily generating severe friction with the edge of the perforation during insertion, resulting in scratches, wear and other damages on the surface of the pin, affecting its service life and mechanical properties. At the same time, when the pin needs to be disassembled for maintenance or replacement at a later stage, the flared part can also provide a better operating space for the disassembly tool, reducing the difficulty of disassembly, improving work efficiency, and facilitating the installation and disassembly of the pin.

[0176] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0177] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. The bridge flexible steel pier has a hidden support-free pin hinge structure, which is characterized by: include: The main ear plate, the lower part of which is arranged in the steel pier, and the upper part of which is vertically extended upward to the main beam box room, is arranged in the longitudinal direction; the upper part of the main ear plate is provided with a first through hole, which is an elliptical structure, and the long axis of the first through hole extends in the longitudinal direction; the first through hole is provided with a first bushing; A pair of secondary ear plates are arranged in parallel on both sides of the main ear plate in the transverse direction, and the bottom of each secondary ear plate is connected to the bottom plate of the main beam; each secondary ear plate is provided with a second through hole corresponding to the first through hole, and each second through hole is circular; a second bushing is provided in the second through hole; A pin shaft, which passes through one of the second through holes, the first through hole and another second through hole in sequence in the transverse direction to connect the main ear plate with a pair of secondary ear plates; a slot is provided on one end of the pin shaft; A baffle plate is clamped in the clamping slot, and the baffle plate is connected to a secondary ear plate adjacent to the clamping slot; The first bushing and the second bushing are made of graphite copper alloy, and the calculation formula of the thickness t of the first bushing and the second bushing is shown in Formula 1: Wherein, F is the maximum load transferred from the pier to the bushing, [σ] is the allowable compressive strength of the graphite copper alloy, λ is the heat dissipation coefficient of the bushing, ΔT is the temperature difference between the inner and outer walls of the bushing, α is the correction coefficient, the correction coefficient α1 corresponding to the first bushing thickness t1 and the correction coefficient α2 corresponding to the second bushing thickness t2, and the sum of α1 and α2 is 1.

2. The bridge flexible steel pier hidden support-free pin hinge structure as claimed in claim 1, characterized in that: Also includes: A steel plate, which is arranged on the top of the pier, and the steel plate is an arc-shaped structure bent downward; A graphite copper lining is arranged on the top of the steel plate.

3. The bridge flexible steel pier hidden support-free pin hinge structure as claimed in claim 2, characterized in that: A plurality of adaptive adjustment blocks are arranged at intervals on the inner walls of the first bushing and the second bushing, and the adaptive adjustment blocks are shape memory alloys with wedge-shaped structures.

4. The bridge flexible steel pier hidden support-free pin hinge structure as claimed in claim 3, characterized in that: The upper part of the main ear plate is provided with first reinforcing plates on both sides in the transverse direction, and the lower part of the main ear plate is provided with stiffening ribs on both sides in the transverse direction; each secondary ear plate is provided with second reinforcing plates on both sides in the transverse direction.

5. The bridge flexible steel pier hidden support-free pin hinge structure as claimed in claim 4, characterized in that: Also includes: A plurality of first impact force sensors are embedded in the upper portion of the main ear plate at intervals, and the first impact force sensors are used to monitor the impact force received by the main ear plate; A plurality of second impact force sensors are embedded in the pin shaft at intervals along the axial direction of the pin shaft, and the second impact force sensors monitor the impact force received by the pin shaft; A plurality of temperature sensors are arranged on the pin shaft at intervals along the axial direction of the pin shaft, and the temperature sensors are used to monitor the working temperature of the pin shaft in real time; A locking mechanism, which is disposed on the first reinforcing plate, and is used to lock the pin shaft; A controller is connected to multiple first impact force sensors, multiple second impact force sensors, a temperature sensor, and a locking mechanism; the controller is configured to collect a first detection value of the first impact force sensor, a second detection value of the second impact force sensor, and a third detection value of the temperature sensor, the controller inputs the first detection value, the second detection value, and the third detection value into a pre-constructed connection structure risk prediction model, and outputs a risk warning level of the connection structure. When the risk warning level is not less than a preset high risk threshold, the controller sends an alarm signal and simultaneously starts the locking mechanism to lock the pin shaft.

6. The bridge flexible steel pier hidden support-free pin hinge structure as claimed in claim 5, characterized in that: The risk warning level of the output connection structure has been optimized and adjusted, specifically: When the risk warning level is less than the preset high-risk warning value, and the ratio of the first detection value to the theoretical bearing impact force of the main ear plate is greater than 0.6, the controller calculates the change rate of the first detection value within a historical week. If the change rate of the first detection value exceeds 5%, the risk warning level is adjusted to the high-risk threshold.

7. The bridge flexible steel pier hidden support-free pin hinge structure as claimed in claim 6, characterized in that: The optimization and adjustment of the risk warning level of the connection structure also includes: When the risk warning level is less than the preset high risk warning value and the third detection value is greater than 50°C, the risk warning level is adjusted once for every 5°C increase in the third detection value relative to 50°C. The risk warning level after each adjustment is 1.1 times the value of the previous risk warning level.

8. The bridge flexible steel pier hidden support-free pin hinge structure as claimed in claim 7, characterized in that: The controller is also set to send a low-risk warning signal once every hour if the ratio of the risk warning level after optimization and adjustment to the high-risk warning threshold is greater than 0.5 and less than 0.65; If the ratio of the risk warning level after optimization and adjustment to the high risk warning threshold is greater than or equal to 0.65 and less than 1, the controller will issue a medium risk warning signal and send it every 0.3 hours; If the ratio of the optimized and adjusted risk warning level to the high-risk warning threshold is greater than or equal to 1, the controller sends a continuous high-risk warning signal and starts the locking mechanism to lock the pin.

9. The bridge flexible steel pier hidden support-free pin hinge structure as claimed in claim 5, characterized in that: The first reinforcing plate is provided with a plurality of mounting grooves; the pin shaft is provided with a plurality of locking holes, which are arranged one by one corresponding to the plurality of mounting grooves; The locking mechanism comprises: A plurality of drivers, one driver is arranged in each installation slot; each driver is connected to a controller; A plurality of locking tongues are provided, and each driver has a locking tongue at its output end. Each driver drives the locking tongue to move along the radial direction of the pin shaft and can be inserted into a corresponding locking hole.

10. The bridge flexible steel pier hidden support-free pin hinge structure as claimed in claim 5, characterized in that: The inlet end and the outlet end of the first perforation are both expanded, the expansion angle is 10-20 degrees, and the expansion length is 0.3-0.5 times the diameter of the pin shaft.

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