Rigidity-adjustable semi-elastic beam plate connecting structure and mounting method

Abstract

The invention discloses a rigidity-adjustable semi-elastic beam-slab connecting structure and a mounting method, and aims to solve the problems that the rigidity of an existing beam-slab connecting device is not easy to adjust and the existing beam-slab connecting device is difficult to disassemble in the using process. The connecting structure comprises a base pedestal made of high-strength steel, a positioning steel sleeve, a high-heat-resistance rubber layer wrapping the connecting piece, shape memory alloy embedded in the rubber layer, a temperature control module, a magnetic force control module, a high-strength bolt and a magneto-rheological shock absorber providing accurate braking force, wherein the magneto-rheological shock absorber is arranged at the top of the trapezoidal connecting piece; and the bridge deck is in contact with the upper bridge deck. A position is reserved on the base pedestal, and all the parts are sequentially installed according to the steps. The device has the advantages of being detachable, adjustable in rigidity, excellent in damping effect, easy and convenient to install and the like, solves the problems that in the using process of an existing beam and slab connecting device, the rigidity is not easy to adjust, and the device is difficult to detach, and is suitable for engineering structures such as bridges and buildings needing to be rapidly detached and controllable in rigidity.

Description

Technical Field

[0001] The invention relates to an installation method of a semi-elastic beam-slab connection structure with adjustable stiffness, belonging to the technical field of detachable beam-slab connection devices. Background Art

[0002] At present, in modern engineering structures and architectural designs, beam-slab connection structures are key load-bearing and connection components. How to achieve detachable beam-slab connection with controllable stiffness has become a difficult problem at this stage. Nowadays, when carrying out underground work at night in transportation hubs, it is necessary to ensure the normal operation of daytime traffic. Therefore, it is urgent to propose a semi-elastic beam-slab connection structure with adjustable stiffness to minimize the impact on ground traffic during underground work in transportation hubs. However, traditional beam-slab connection methods mainly include welding, bolt connection, etc. These connection methods usually require a large number of on-site construction operations, with complex processes and are difficult to meet the requirements of convenient disassembly and controllable stiffness of the structure. Therefore, it is necessary to propose an installation method for a semi-elastic beam-slab connection structure with adjustable stiffness.

[0003] For example, Chinese patent document CN118187287A discloses an assembled beam-slab connection structure, wherein first recesses are respectively provided on two side walls of the prefabricated beam opposite to each other along a first direction, a side of the prefabricated plate close to the prefabricated beam is connected to the first recess, the prefabricated beam is provided with at least one through groove extending along the first direction, the prefabricated plate is provided with at least one second recess extending along the first direction, two second recesses opposite to each other along the first direction are connected to the through groove and form a first groove, a first bottom wall of the second recess is provided with a second groove opening toward the connecting member, the connecting member includes a first extension portion, the connecting member is accommodated in the first groove, and at least part of the first extension portion is accommodated in the second groove to connect the prefabricated beam and the two prefabricated plates. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that when carrying out underground work in transportation hub areas, traditional pavement detachable beam-slab connection methods such as welding and bolt connection require a large number of on-site construction operations, the process is complicated, and it is difficult to meet the needs of convenient disassembly of the structure and controllable stiffness.

[0005] The present invention is a semi-elastic beam-plate connection structure with adjustable stiffness, characterized in that the structure comprises a base pedestal made of high-strength steel, a high-heat-resistant rubber layer wrapped outside the base pedestal, a shape memory alloy (SMA) embedded in the rubber layer, a current control module, a high-strength bolt for fixing on the top of the base pedestal, a magnetorheological damper for providing precise braking force, a magnetic force control module, and a graphene heat sink located around the magnetorheological damper. A position is reserved on the base pedestal, and each component is installed in sequence according to the steps.

[0006] As a preferred solution of the present invention, the rubber of the rubber layer is suitable for a temperature range of -60°C to +260°C, and is commonly used in high-temperature sealing and bonding applications.

[0007] As a preferred solution of the present invention, the shape memory alloy adopts Nitinol 55 type nickel-titanium alloy, which has significant shape memory effect, excellent superelasticity and high fatigue resistance. The Nitinol 55 is resistively heated by connecting the electrodes to a power source, so that it changes between the martensite phase (low stiffness) and the austenite phase (high stiffness) to adjust the stiffness of the connection structure. The SMA temperature control module is used to ensure that the heating temperature is within the phase transition temperature range of Nitinol 55 to ensure the realization of the shape memory effect.

[0008] As a preferred solution of the present invention, the vibration sensor (ADX345) collects the vibration parameters of the bridge deck and feeds them back to the magnetic control module to calculate the required control current. The drive circuit converts the signal output by the magnetic control module into an appropriate current to drive the magnetorheological damper. The magnetorheological damper generates a control force through the electromagnetic force generated by the current, and the control force can be used to offset or reduce the vibration in the system. By adjusting the current passing through the magnetorheological damper, the magnitude and direction of the electromagnetic force can be changed, thereby adjusting the effect of vibration absorption.

[0009] As a preferred solution of the present invention, the magnetorheological damper is surrounded by a graphene heat sink, which can absorb and conduct the heat generated by the magnetorheological damper and dissipate it into the surrounding environment, thereby controlling the internal temperature of the system within a safe range to prevent overheating and ensure stable operation of the equipment.

[0010] As a preferred solution of the present invention, the connector has two force transmission modes. 1. Rigid force transmission mode in the vertical direction: In the vertical direction, the force is input from the bridge deck, passes through the magnetorheological damper and the base pedestal in sequence, and finally reaches the lower I-beam. 2. Semi-elastic vibration damping force transmission mode in the horizontal direction: The positioning steel sleeve-rubber layer-base pedestal system forms a semi-elastic connection system, which consumes part of the energy through deformation during horizontal vibration to reduce structural vibration.

[0011] As a preferred solution of the present invention, the base pedestal cast in the I-beam and the slab has anchor steel bars welded at the bottom and around it, respectively, to enhance the anchoring force between the base pedestal and the I-beam and the bridge deck, thereby ensuring that the structure is firm and reliable.

[0012] A method for installing a semi-elastic beam-slab connection structure with adjustable stiffness comprises the following steps: S1: According to the structural and dimensional requirements of the designed base pedestal, a base pedestal with a solid structure is formed by machining high-strength steel, and the base pedestal has a conical side surface. Simultaneously, a positioning steel sleeve with a hollow structure is obtained by machining, and the positioning steel sleeve has a conical hole structure, and anchor steel bars are welded on the side surface of the positioning steel sleeve; S2: Use the positioning mold to ensure the correct position and angle of the base pedestal and positioning steel sleeve on the top of the concrete I-beam and the bridge deck. Fix the connectors and positioning steel sleeves to ensure that they will not move during the pouring process. In the predetermined order, start pouring the concrete I-beam and bridge deck. When pouring, make sure that the concrete can be evenly filled into every corner to avoid voids and looseness; S3: After the concrete I-beam and bridge deck have completed shrinkage creep, prefabricate a high-temperature resistant rubber layer according to the shape of the base pedestal and cover the outside of the base pedestal. Design and prefabricate a shape memory alloy according to the shape of the rubber layer. Evenly embed the memory alloy into the rubber layer to ensure that its position is fixed. Both ends of the memory alloy expose joints on the top of the rubber layer for resistance heating. Pour the mixed thermal conductive silicone into the interior to ensure that the material can evenly fill the gaps around the shape memory alloy. After the pouring is completed, use a special tool to seal the pouring port to ensure that the pouring material does not leak out, so that the rubber layer forms an elastic transition between the base pedestal and the positioning steel sleeve; S4: Install an external power supply, a temperature acquisition sensor (RTD - PT100), a vibration sensor (ADX345) and a magnetorheological damper on the upper surface of the base pedestal, and ensure that the magnetorheological damper can contact the bridge deck above, forming a current control module and a magnetic control module respectively. The magnetic control module is responsible for receiving signals from the vibration sensor (ADX345), analyzing vibration data in real time, and adjusting the damping force of the magnetorheological damper according to the preset control algorithm to optimize the vibration control of the structure. The current control module adjusts the current by receiving the vibration parameters of the vibration sensor (ADX345) and the feedback of the temperature acquisition sensor (RTD -PT100), thereby heating the SMA to achieve the purpose of adjusting the stiffness of the system.

[0013] S5: Reserve channels for power and control cables, and connect the power and control cables of the shape memory alloy and magnetorheological damper to the external power supply. Turn on the external power supply, check its connection with the shape memory alloy and magnetorheological damper, ensure that the system can correctly identify and control each device, and perform preliminary current on-off tests to ensure that each device can operate as expected. Use the external power supply to monitor and adjust the working status of the magnetorheological damper and shape memory alloy in real time to debug the system; S6: applying electricity to heat the shape memory alloy so that it changes between the martensite phase and the austenite phase, adjusting the stiffness of the connection structure, controlling the magnetorheological damper, adjusting the braking force generated by the magnetorheological damper, and achieving the suppression of the vibration of the bridge deck; S7: After installation, use the hanging lifting mechanism to accurately connect the base pedestal, accurately insert the bolts into the reserved bolt holes, and use the electronic torque wrench to tighten the nuts and bolts.

[0014] Beneficial effects: Compared with the existing technology, the present invention has the following advantages: (1) The connection structure of the present invention adopts a modular design, and the installation and disassembly process is simple. The independent control modules of the magnetorheological damper and SMA make it possible to complete maintenance or replacement with simple operations, which greatly reduces maintenance costs and time and improves the reliability and maintainability of the system.

[0015] (2) The present invention embeds a shape memory alloy (SMA) in the rubber layer and uses electric current heating to achieve phase change of the SMA, thereby adjusting the stiffness of the connection structure. This design allows the stiffness of the beam-slab connection structure to be dynamically adjusted according to actual needs to meet the needs of different working conditions.

[0016] (3) The combination of the semi-elastic vibration-absorbing force transmission mode in the horizontal direction and the rigid force transmission mode in the vertical direction greatly improves the vibration reduction effect of the connection structure.

[0017] (4) Through dynamic adjustment of stiffness and efficient vibration reduction measures, the present invention effectively reduces stress concentration and vibration impact at the beam-slab connection, thereby extending the service life of the structure. The protective effect of the rubber layer reduces the erosion and damage of the connecting parts by the external environment, thereby improving the overall durability of the structure.

[0018] (5) The design of the graphene heat sink combined with the temperature control module significantly improves the temperature management capability of the system and ensures the stable operation of the magnetorheological damper and shape memory alloy (SMA). BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is an overall schematic diagram of the present invention; Figure 2 This is a structural diagram of the positioning steel sleeve of the present invention; Figure 3 It is a structural diagram of the base pedestal of the present invention; Figure 4 It is a detailed structural diagram of the base pedestal of the present invention; Figure 5 It is the injection molding process of the rubber layer; Figure 6 This is the overall structure diagram of the magnetorheological shock absorber; Figure 7This is the structural principle diagram of the magnetorheological shock absorber; Figure 8 is a schematic diagram of a current control module of the present invention; Fig. 9 It is a schematic diagram of the magnetic control module of the present invention.

[0020] In the figure: 002 UHPC I-beam, 001 bridge deck, 110 bolt holes, 120 positioning steel sleeves, 130 anchor steel bars, 210 base pedestal, 220 anchor steel bars, 230 high-strength bolts, 311 lead, 312 graphene heat sink, 321 electrode, 330 vibration sensor No. 1, 331 vibration data collector, 313 temperature acquisition sensor, 340 current control module, 350 power supply, 360 vibration sensor No. 2, 370 magnetic control module, 390 magnetorheological shock absorber, 501 coil spring, 502 piston connecting rod, 503 damping channel, 504 piston, 505 magnetorheological fluid, 506 cover plate, 420 mold, 410 shape memory alloy, DETAILED DESCRIPTION

[0021] To facilitate understanding of the structure of the present invention, the following is a description in conjunction with the accompanying drawings and embodiments. Unless otherwise specified, all technical and scientific terms used herein are as close as possible to and refer to terms commonly understood by ordinary technicians in the technical field to which this application belongs. Example

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] like Figures 1 to 9 As shown in the figure, a semi-elastic beam-slab connection structure with adjustable stiffness is achieved by fast assembly connection of bolts and nuts to realize the detachable beam-slab, which can be used cyclically after removal. In this structure, a rubber layer embedded with memory alloy (SMA) is wrapped around the base pedestal to adjust the stiffness of the connection, and a magnetorheological damper is installed on the top surface of the base pedestal to reduce vibration, so as to achieve the goal of fast installation and shock absorption and earthquake resistance.

[0024] This embodiment describes in detail a semi-elastic beam-slab connection structure with adjustable stiffness, and introduces the construction process of the structure.

[0025] The specific implementation steps are as follows: First, modularly prepare and process materials to select high-strength steel to make the base pedestal 210 and the positioning steel sleeve 120.

[0026] According to the design requirements, a CNC lathe is used to process steel into a base pedestal 210 of a required size. The base pedestal 210 is a solid steel column, which is turned into an outer contour with a truncated cone structure.

[0027] A high-strength bolt 230 is welded at the top center of the base pedestal, or a hole is drilled and threaded at the top center of the base pedestal to form a bolt hole, and a high-strength bolt 230 is fixed and installed by threading. The high-strength bolt 230 is used to cooperate with the through hole on the steel column connector positioning steel sleeve 120, and is fastened with a nut to complete a quick fastening connection. During the welding process, ensure that the weld is full and free of defects to ensure the connection strength.

[0028] Similarly, a circle of six anchoring steel bars 220 are welded at the bottom of the base pedestal 210, or threaded holes are drilled and mechanically fixed to form six anchoring steel bars 220. The function of the anchoring steel bars 220 is to enhance the anchoring force between the base pedestal 210 and the UHPC I-beam 002, and improve the overall anti-firmness performance, that is, to ensure that the base pedestal is installed securely.

[0029] The substrate pedestal 210 is a load-bearing component.

[0030] The rubber layer is formed on the conical outer surface of the base seat 210. Specifically, a cleaning agent (such as isopropyl alcohol) is used to clean the conical outer surface of the base seat 210 connector to ensure that it is free of grease, dust and impurities. The surface is roughened (such as sandblasting or chemical etching, mechanical embossing) to improve the adhesion of the rubber layer.

[0031] Apply a layer of rubber-specific adhesive to the conical outer surface of the base pedestal 210, ensuring even coverage, and allow to dry according to the adhesive instructions.

[0032] Forming process of rubber layer: According to the outer contour size and shape of the base pedestal 210, a rubber infusion mold is designed, that is, a mold 420 is set on the periphery of the base pedestal to form an annular rubber infusion mold cavity. According to the size design of the rubber infusion mold cavity, a shape memory alloy 410 of appropriate length is selected, and the shape memory alloy 410 has a spiral spring shape. The shape memory alloy 410 has a unique shape memory effect and elastic controllable characteristics. The shape memory alloy 410 is fixed in the rubber infusion mold cavity to ensure its accurate position. Among them, the electrodes 321 and the wires at both ends of the shape memory alloy 410 are exposed outside the rubber layer, that is, the electrodes are led out so as to connect to an external power supply and can be electrically heated (after being electrically heated, its stiffness can be changed). Pour the fluid rubber into a stirrer, add a catalyst in proportion, and stir evenly. Inject the mixed fluid rubber into the rubber infusion mold cavity to ensure that the rubber evenly covers the base pedestal 210 and the shape memory alloy 410. After this process, a rubber layer of equal thickness with shape memory alloy wrapped inside is formed around the base pedestal. After the mold is removed, conductive glue or welding is used to ensure that the electrode 321 is firmly connected to the shape memory alloy 410. The electrode 321 controls the stiffness of the shape memory alloy through electric current.

[0033] The so-called shape memory alloy has the following characteristics: when heated, it undergoes a phase change from the martensite phase to the austenite phase, which significantly increases its stiffness. Therefore, after the shape memory alloy 410 is embedded in the rubber layer, the vertical and circumferential stiffness of the rubber layer can be adjusted in real time by heating, providing active vibration control under different working conditions.

[0034] The rubber layer is in direct contact with the conical inner wall of the inner wall of the positioning steel sleeve 120 above, forming a semi-rigid elastic connection. The high elasticity and flexibility of the rubber layer enable it to buffer and absorb the vibration of the bridge deck 001, playing the role of vibration isolation, buffering and energy absorption. This helps to reduce the impact of vibration on the structure, especially under low-frequency vibration conditions, the presence of the rubber layer can effectively reduce vibration transmission. The combination of the rubber layer and the shape memory alloy 410 inside it enables the system to automatically adjust the stiffness of the structure under different working conditions. When the external vibration is small, the shape memory alloy 410 remains in a low stiffness state, and the rubber layer provides the main vibration isolation function; when the vibration is large, the shape memory alloy 410 is heated to increase the overall stiffness of the system and suppress vibration.

[0035] Since a high-strength bolt is arranged at the center of the upper surface of the base pedestal, the high-strength bolt is arranged vertically, and a magnetorheological damper 390 is fixedly installed on the top of the base pedestal where the high-strength bolt 230 is located, and the magnetorheological damper 390 is arranged in parallel with the high-strength bolt 230 at the same center. According to the design drawings, the position of the magnetorheological damper 390 on the base pedestal 210 is determined and installed to ensure that the position is flat for subsequent operations.

[0036] The main components of the disc-shaped magnetorheological damper 390 are: four coil springs 501, which are used to provide basic elastic restoring force, ensure the basic mechanical stability of the system when the piston 504 moves, and provide elastic support. The coil spring 501 can absorb some low-frequency vibrations and provide basic shock absorption and basic reset capabilities when there is no current. Four piston connecting rods 502 correspond to the four coil springs 501 one by one. The top of the piston connecting rod 502 is fixedly connected to the cover plate 506, and the bottom is connected to the piston 504.

[0037] After installation, the cover plate 506 contacts and cooperates with the top of the positioning steel sleeve 120 to complete the vertical force support. When the bridge deck 001 is stressed and transmits vibration downward, the vibration of the cover plate 506 drives the vertical movement of the piston connecting rod 502 and the piston 504, thereby realizing vertical shock absorption. The piston 504 and the controllable damping channel 503 located on the piston 504, the piston 504 divides the piston cavity into two, the upper and lower sub-cavities. Through the controllable damping channel 503, the magnetorheological fluid 505 can flow from one side of the piston 504 to the other side. The piston 504 performs a linear piston motion in the cavity, so that the magnetorheological fluid moves in the piston cavity, generates a damping force, and realizes the shock absorption function by controlling the speed and amount of liquid flow. The magnetorheological fluid 505 is filled in the internal cavity of the shock absorber. When a magnetic field is applied, the magnetic particles in the liquid are arranged in a chain structure, thereby increasing the viscosity of the liquid and generating a damping effect. The piston connecting rod 502 has an electromagnetic coil inside, and the electromagnetic coil generates a magnetic field when it is energized. The magnetic field is concentrated around the magnetorheological fluid 505 through a magnetic conductive material (such as an iron core). As the current changes, the magnetic field strength will also change accordingly, thereby adjusting the viscosity of the magnetorheological fluid.

[0038] That is to say, the magnetorheological shock absorber 390 includes a shock absorber housing, a coil spring, a piston, a piston connecting rod, a cover plate and a magnetorheological fluid (a liquid medium), wherein the piston is installed in the piston cavity of the shock absorber housing, four piston connecting rods are connected to the piston and extend to the outside of the shock absorber housing and are directly fixedly connected to the cover plate, the coil spring is arranged between the shock absorber housing and the cover plate, the piston has a damping channel for allowing magnetorheological medium to pass through, and the piston cavity is filled with magnetorheological fluid; the piston connecting rod has an electromagnetic coil inside, and the electromagnetic coil generates a magnetic field when energized, and the magnetic field adjusts the viscosity of the magnetorheological fluid.

[0039] Initial state (no current): When the system is not powered, the magnetic particles of the magnetorheological fluid 505 are randomly distributed and the viscosity of the fluid is low. At this time, the piston can move relatively freely in the fluid and the damping force generated is small. The shock absorber mainly relies on the coil spring to provide the basic mechanical shock absorption effect.

[0040] After power is applied (magnetic field is generated): 1. The electromagnetic coil generates a magnetic field: When powered, the electromagnetic coil generates a magnetic field, and the magnetic lines of force pass through the region of the magnetorheological fluid 505. As the current increases, the magnetic field strength increases.

[0041] 2. Changes in magnetorheological fluid 505: The magnetic field acts on the magnetic particles in the magnetorheological fluid 505. The particles are quickly arranged into a chain structure under the action of the magnetic field, and the viscosity of the liquid increases. The increase in viscosity directly increases the flow resistance of the liquid, thereby increasing the damping force of the shock absorber.

[0042] 3. Damping force control: By adjusting the current, the electromagnetic coil controls the strength of the magnetic field. In a weak magnetic field, the particles are arranged loosely, the liquid viscosity is low, and the damping force is small; in a strong magnetic field, the particles are arranged more closely, the liquid viscosity is high, and the damping force increases accordingly.

[0043] Use adhesive to install the vibration sensor No. 1 (ADX345) 330 on the top of the base pedestal 210, and paste the temperature acquisition sensor (RTD-PT100) 313 at the shape memory alloy 410 so that it is fixed at the predetermined position of the mold. Connect the output signal lines of the vibration sensor No. 1 (ADX345) 330 and the temperature acquisition sensor (RTD - PT100) 313 to the current control module 340, refer to Figure 4 and Figure 8 The current control module 340 monitors the temperature change of the shape memory alloy 410 and the vibration state of the structure in real time by processing the monitoring results of the first vibration sensor (ADX345) 330 and the temperature acquisition sensor (RTD-PT100) 313. Two power supply 350 access electrodes are set outside the connector or at a suitable position. These electrodes can be made of materials with good conductivity (such as copper or nickel) to ensure that they can withstand large currents and have good conductivity. Connect the electrode 321 of the shape memory alloy 410 to the power supply to ensure good conductivity. Use insulating tape to wrap the wiring to ensure that there is no exposed wire to prevent short circuits and leakage.

[0044] According to the setting of the current control module 340, the shape memory alloy 410 is heated. The current is gradually increased, the initial current is set to 5A, and the power is turned on for 3 minutes. The temperature of the shape memory alloy 410 is monitored using the temperature acquisition sensor (RTD-PT100) 313 to ensure uniform heating and controllable temperature. When the temperature is stable at 100°C, infrared thermal imaging technology is used to observe the thermal effect of the shape memory alloy 410, and then the state and phase change of the shape memory alloy 410 are determined to verify the heating effect.

[0045] The first vibration sensor (ADX345) 330 is started to collect vibration parameters when the vehicle passes through the bridge deck. The first vibration sensor (ADX345) 330 feeds data back to the current control module 340, and the current control module 340 analyzes the vibration parameters and calculates the required adjustment current according to the preset vibration control strategy. If the vibration data collector 331 determines that the vibration amplitude exceeds the limit, the current control module 340 will excite the current to heat the shape memory alloy 410. According to the vibration parameters, the current regulation mode is set: if the vibration data collector 331 determines that the vibration amplitude is less than 1.0mm, the system cuts off the power supply, so that the shape memory alloy 410 is in the low-temperature martensite phase, maintaining relative flexibility to adapt to the conditions of slight vibration; if the vibration data collector 331 determines that the vibration amplitude is 1-2mm, the current control module 340 sets the current to 7A, powers on for 2 minutes, and heats the shape memory alloy 410 to about 120°C. At this time, the stiffness of the shape memory alloy 410 is relatively low, and the system stiffness is moderate, which helps to absorb a certain amount of vibration energy; if the vibration data collector 331 determines that the vibration amplitude is greater than 2mm, the current control module 340 sets the current to 10A, powers on for 1 minute, and heats the shape memory alloy 410 to about 150°C, so that it enters the austenite phase. In this state, the shape memory alloy 410 has a higher stiffness, which can enhance the overall stiffness of the structure and reduce vibration. In this system, heating the shape memory alloy 410 to different temperatures can control its phase change process, thereby controlling the stiffness of the shape memory alloy 410. Active vibration control can be achieved in bridge structures by adjusting the stiffness of shape memory alloy 410. This control not only improves the stability of the structure, but also enhances its adaptability to different dynamic loads (such as when vehicles pass by).

[0046] Use conductive glue or welding tools to connect the lead wire 311 of the electromagnetic coil in the piston connecting rod to the power line, ensuring that the connection is firm and the wire is not loose. Use insulating tape to wrap the connection to ensure that there is no exposed wire to prevent short circuit and leakage. Connect the power line and control cable to the magnetic control module 370. The magnetic control module 370 controls the current generated by the magnetorheological damper 390 by receiving the vibration parameters collected by the second vibration sensor (ADX345) 360, thereby controlling the magnetic force. Ensure that the connection is correct and use a multimeter to measure the resistance of the electromagnetic coil 507 to ensure that it is within the specified range. Use an insulation resistance tester to check the insulation of the wire to ensure that there is no leakage. Gradually power on and test the working state of the magnetorheological damper 390. First, set the magnetic control module 370 to the lowest current state (for example, 0A), gradually increase to 50A, observe the initial response of the damper, and ensure that it can work properly. Start from 50A and increase by 10A or 20A each time to gradually adjust the current to the expected maximum value of 350A. After each adjustment, observe the working status of the damper. During the test, the damping force generated by the damper under different currents should be observed and recorded, and the performance of the damper should be analyzed as the current changes to ensure the control effect of the system vibration. Start the magnetorheological damper 390, gradually increase the current, and observe the changes in the vibration parameters fed back by the second vibration sensor (ADX345) 360. According to the vibration parameters, set the current adjustment mode: if the vibration amplitude is less than 1.0mm, the magnetic control module 370 sets the current to 80A, and the magnetic force generated is about 2000N; if the vibration amplitude is 1.0mm to 2.0mm, the magnetic control module 370 sets the current to 200A, and the magnetic force generated is about 5000N; if the vibration amplitude is greater than 2.0mm, the magnetic control module 370 sets the current to 350A, and the magnetic force generated is about 10000N; if the vibration amplitude is less than 0.1mm, cut off the power supply.

[0047] A graphene heat sink 312 is installed on the top of the base pedestal around the magnetorheological damper 390. The graphene heat sink 312 is made of a film or sheet made of graphene, a high thermal conductivity material. The heat generated by the magnetorheological damper 390 is absorbed and conducted, and dissipated into the surrounding environment to prevent overheating. By increasing the heat dissipation surface area and optimizing the shape design of the heat sink, the heat sink achieves efficient heat conduction and dissipation, ensuring that the internal temperature of the system remains within a safe range. After the above steps are completed, the beam-plate connector is installed through a hanging hoisting mechanism. First, the UHPC I-beam 002 with the base pedestal 210 embedded is placed in a predetermined position, and the plate 001 with the positioning steel sleeve 120 prefabricated and fixed inside is hoisted in a predetermined position, so that the high-strength bolts 230 welded on the base pedestal 210 are aligned with the bolt holes 110 reserved for the positioning steel sleeve 120. Finally, an electronic torque wrench is used to tighten the nuts and high-strength bolts 230 to ensure the stability and detachability of the connection.

[0048] The entire construction process must be carried out in strict accordance with the design and construction specifications to ensure the accuracy and quality of each link. Through the semi-elastic beam-slab connection structure and installation process with adjustable stiffness, the impact on ground traffic when building subways in transportation hubs can be effectively reduced, and construction efficiency and safety can be improved.

[0049] In this example, a semi-elastic beam-plate connection structure with adjustable stiffness includes a base pedestal made of high-strength steel, a high-heat-resistant rubber layer wrapped around the outside of the connection, a shape memory alloy (SMA) embedded in the rubber layer, an SMA temperature control module, a high-strength bolt located on the top of the base pedestal, a magnetorheological damper providing braking force, an electromagnetic control module of the magnetorheological damper, and a graphene heat sink located around the magnetorheological damper. A good position is reserved on the base pedestal, and each component is installed in sequence according to the steps.

[0050] In this example, the rubber of the rubber layer is suitable for a temperature range of -60°C to +260°C and is commonly used in high-temperature sealing and bonding applications.

[0051] In this example, the shape memory alloy is a nickel-titanium alloy of the Nitinol 55 type, which has a significant shape memory effect, excellent superelasticity, and high fatigue resistance. The Nitinol 55 is resistively heated by connecting the electrodes to a power source, so that it changes between the martensite phase (low stiffness) and the austenite phase (high stiffness) to adjust the stiffness of the connection structure. The SMA temperature control module is used to ensure that the heating temperature is within the phase transition temperature range of Nitinol 55 to ensure the realization of the shape memory effect.

[0052] In this example, the second vibration sensor (ADX345) collects the vibration parameters of the bridge deck and feeds them back to the magnetic control system to calculate the required control current. The drive circuit converts the signal output by the magnetic control system into an appropriate current to drive the magnetorheological damper. The magnetorheological damper generates a control force through the electromagnetic force generated by the current, which can be used to offset or reduce the vibration in the system. By adjusting the current passing through the magnetorheological damper, the magnitude and direction of the electromagnetic force can be changed, thereby adjusting the effect of vibration absorption.

[0053] In this example, the magnetorheological damper is surrounded by a graphene heat sink, which can absorb and conduct the heat generated by the magnetorheological damper and dissipate it into the surrounding environment, thereby controlling the internal temperature of the system within a safe range to prevent overheating and ensure stable operation of the equipment.

[0054] In this example, the base pedestal cast in the I-beam and the plate is respectively welded with anchor steel bars at the bottom and around the pedestal to enhance the anchoring force between the base pedestal and the I-beam and the plate, thereby ensuring that the structure is firm and reliable.

[0055] In this example, the connector has two force transmission modes, namely, 1. Rigid force transmission mode in the vertical direction: in the vertical direction, the force is input from the bridge deck, passes through the magnetorheological damper and the base pedestal in sequence, and finally reaches the lower I-beam. 2. Semi-elastic vibration damping force transmission mode in the horizontal direction: the positioning steel sleeve 120, the rubber layer 420, and the base pedestal 210 system form a semi-elastic connection system, which consumes part of the energy through deformation when vibrating in the horizontal direction, thereby reducing structural vibration.

[0056] It should be noted that a semi-elastic beam-slab connection structure with adjustable stiffness includes the following steps: according to the structural and dimensional requirements of the designed base pedestal 210, the base pedestal 210 and the positioning steel sleeve 120 of the base pedestal are prefabricated with high-strength steel. The prefabricated base pedestal 210 and the positioning steel sleeve 120 are cast into the I-beam 002 and the bridge deck 001 respectively, and the outer surface of the positioning steel sleeve 120 is provided with 130 anchor steel bars. After the I-beam 002 completes shrinkage creep, a high-temperature resistant rubber layer 420 is prefabricated according to the shape of the base pedestal 210 and coated on the outside of the base pedestal. A shape memory alloy (SMA) is designed and prefabricated according to the shape of the rubber layer, and the shape memory alloy uses a nickel-titanium alloy (NiTi SMA). The NiTi SMA is uniformly embedded in the rubber layer to ensure that its position is fixed. The two ends of the nickel-titanium alloy expose joints at the top of the rubber layer for connecting to an external power supply. The current control module, magnetorheological damper, vibration sensor (ADX345) and magnetic control module of shape memory alloy are installed on the upper surface of the base pedestal, and the magnetorheological damper is ensured to be in contact with the bridge deck above. A channel for the control cable is reserved, and the power supply and control cables of the SMA and the magnetorheological damper are connected to the battery pack, and the system is debugged. The working status of the SMA and the magnetorheological damper is observed by infrared thermal imaging technology. The shape memory alloy is heated by resistance to make it transform between the martensite phase and the austenite phase, and the stiffness of the connection structure is adjusted. The power on and off of the magnetorheological damper is controlled to adjust the braking force it generates, so as to control the vibration of the bridge deck. A small graphene heat sink is installed around the magnetorheological damper to ensure effective heat dissipation in a limited space, so that the magnetorheological damper and SMA are stable and reliable during efficient operation. After the installation is completed, the base pedestal is accurately connected using a hanging hoisting mechanism, the bolts are accurately inserted into the reserved bolt holes, and the nuts and bolts are tightened using an electronic torque wrench.

Claims

1. A semi-elastic beam-slab connection structure with adjustable stiffness, characterized in that: It includes an I-beam, a bridge deck, a base pedestal installed between the two, and a positioning steel sleeve, among which: The base pedestal is a conical pedestal of solid structure, the outer side of the base pedestal has a circumferentially coated rubber layer and the rubber layer is embedded with a shape memory alloy, the shape memory alloy is in the shape of a spiral spring, and a vertically arranged high-strength bolt is provided at the top center position of the base pedestal, the high-strength bolt passes through the positioning steel sleeve and is fixed with a fastening nut, and a magnetorheological damper, a magnetic control module, a No. 1 vibration sensor, a temperature acquisition sensor, and a current control module are provided on the top surface of the base pedestal, wherein the current control module monitors the temperature change of the shape memory alloy and the vibration state of the structure in real time by processing the monitoring results of the No. 1 vibration sensor and the temperature acquisition sensor; the control current required for calculating the control current is fed back to the magnetic control module, the drive circuit converts the signal output by the magnetic control module into an appropriate current, drives the magnetorheological damper, and the magnetorheological damper generates a control force through the electromagnetic force generated by the current, and the control force can be used to offset or reduce the vibration in the system, adjust the current passing through the magnetorheological damper, and change the magnitude and direction of the electromagnetic force; The positioning steel sleeve is a hollow structure with a conical cavity that matches the shape of the base pedestal, and the two are sleeved between the I-beam and the bridge deck, wherein the rubber layer is located at the annular conical joint surface between the positioning steel sleeve and the base pedestal, and the magnetorheological damper is located at the horizontal joint surface between the positioning steel sleeve and the base pedestal, forming a semi-elastic connection with adjustable stiffness. The semi-elastic connection enables: in the vertical direction, the force is input from the bridge deck, passes through the positioning steel sleeve, the magnetorheological damper, and the base pedestal in sequence, and finally reaches the lower I-beam; in the horizontal direction, it passes through the positioning steel sleeve, the rubber layer, and the base pedestal, and finally reaches the base pedestal, consuming the vibration energy in the horizontal direction.

2. The semi-elastic beam-slab connection structure with adjustable stiffness according to claim 1, characterized in that: The rubber layer is rubber.

3. The semi-elastic beam-slab connection structure with adjustable stiffness according to claim 1, characterized in that: The shape memory alloy is Nitinol 55 nickel-titanium alloy.

4. The semi-elastic beam-slab connection structure with adjustable stiffness according to claim 1, characterized in that: Graphene heat sinks are attached around the magnetorheological damper.

5. The semi-elastic beam-slab connection structure with adjustable stiffness according to claim 1, characterized in that: The base pedestal cast in the I-beam and the slab is respectively welded with anchor steel bars at the bottom and around, so as to enhance the anchoring force between the base pedestal and the I-beam and the bridge deck.

6. The semi-elastic beam-slab connection structure with adjustable stiffness according to claim 1, characterized in that: The magnetorheological shock absorber comprises a shock absorber housing, a coil spring, a piston, a piston connecting rod, a cover plate and a magnetorheological medium, wherein the piston is installed in a piston cavity of the shock absorber housing, four piston connecting rods are connected to the piston and extend to the outside of the shock absorber housing and are directly fixedly connected to the cover plate, the coil spring is arranged between the shock absorber housing and the cover plate, the piston has a damping channel for allowing the magnetorheological medium to pass through, and the piston cavity is filled with the magnetorheological medium; the piston connecting rod has an electromagnetic coil inside, the electromagnetic coil is energized to generate a magnetic field, and the magnetic field adjusts the viscosity of the magnetorheological medium.

7. A method for forming a semi-elastic beam-slab connection structure with adjustable stiffness, characterized in that: Follow these steps in order S1: According to the structural and dimensional requirements of the designed base pedestal, a base pedestal with a solid structure is formed by machining high-strength steel, and the base pedestal has a conical side surface. Simultaneously, a positioning steel sleeve with a hollow structure is obtained by machining, and the positioning steel sleeve has a conical hole structure, and anchor steel bars are welded on the side surface of the positioning steel sleeve; S2: Use the positioning mold to ensure that the base pedestal and the positioning steel sleeve are in the correct position and angle on the top of the concrete I-beam and the bridge deck. Fix the base pedestal and the positioning steel sleeve to ensure that they will not move during the concrete pouring process. Start pouring the concrete I-beam and bridge deck in the predetermined order. When pouring, ensure that the concrete can be evenly filled into every corner to avoid voids and looseness; S3: After the concrete I-beam and the bridge deck have completed shrinkage creep, a shape memory alloy is designed and prefabricated according to the shape of the rubber layer, the shape memory alloy is placed in a mold cavity and its position is fixed, and fluid rubber is poured into the mold cavity, and a special tool is used to seal the pouring port to form a rubber layer, and electrodes are exposed at both ends of the shape memory alloy on the top of the rubber layer and are electrically connected to an external power supply; S4: A magnetorheological damper, a vibration sensor and a vibration controller are installed on the upper surface of the base pedestal, and the magnetorheological damper is ensured to be in contact with the upper bridge deck. The magnetorheological damper adjusts the magnitude of the damping force by adjusting the magnetic field strength, thereby achieving real-time control of the vibration. The vibration sensor monitors the vibration condition of the bridge deck in real time and provides accurate vibration data, which are used to analyze the health status of the structure and adjust the working status of the magnetorheological damper through the control system. The vibration controller is responsible for receiving signals from the vibration sensor, analyzing the vibration data in real time, and adjusting the damping force of the magnetorheological damper according to a preset control algorithm to optimize the vibration control of the structure. S5: Reserve channels for power and control cables, and connect the electrical connections of the shape memory alloy and magnetorheological damper to the external power supply. Check the connection between the external power supply and the shape memory alloy and magnetorheological damper to ensure that the system can correctly identify and control each device. Perform a preliminary current on-off test to ensure that each device can operate as expected. Use the external power supply to monitor and adjust the working status of the magnetorheological damper and shape memory alloy in real time to debug the system. S6: applying electricity to heat the shape memory alloy so that the shape memory alloy changes between the martensite phase and the austenite phase, adjusting the stiffness of the connection structure, controlling the magnetorheological damper, adjusting the braking force generated by the magnetorheological damper, and achieving the suppression of the vibration of the bridge deck; S7: After installation, use the hanging lifting mechanism to accurately connect the base pedestal, accurately insert the bolts into the reserved bolt holes, and use the electronic torque wrench to tighten the nuts and bolts.

8. The method for installing a semi-elastic beam-slab connection structure with adjustable stiffness according to claim 7, characterized in that: The rubber layer is formed by rubber injection molding.

9. The method for installing a semi-elastic beam-slab connection structure with adjustable stiffness according to claim 7, characterized in that: The shape memory alloy is Nitinol 55 nickel-titanium alloy.

10. The method for installing a semi-elastic beam-slab connection structure with adjustable stiffness according to claim 7, characterized in that: The vibration sensor collects the vibration parameters of the bridge deck and feeds them back to the controller to calculate the required control current. The drive circuit converts the signal output by the controller into an appropriate current to drive the magnetorheological damper. The magnetorheological damper generates a control force through the electromagnetic force generated by the current, which offsets or reduces the vibration in the system.

Images