A staged variable stiffness viscous damper and its installation method and application

Abstract

The present invention belongs to the field of bridge seismic isolation and discloses a staged variable stiffness viscous damper, an installation method thereof, and an application thereof. The staged variable stiffness viscous damper includes an outer cylinder body and two inner cylinder bodies arranged inside the outer cylinder body. Pistons are respectively arranged inside the two inner cylinder bodies. The piston rods penetrate the outer cylinder body and are connected to the pistons. A structural disc is prefabricated on the piston rod. A group of force transmission rods are evenly arranged in the circumferential direction of the structural disc. Friction blocks are connected to the two ends of the force transmission rods. A pad is installed on the inner cylinder body near the end of the outer cylinder body through a bayonet. A first spring group is arranged between the friction block and the pad. A second spring group is arranged at the ends of the inner cylinder body and the outer cylinder body. A friction damping module is also arranged between the outer cylinder body and the inner cylinder body. The present invention adopts the dual synergy of friction damping and viscous damping energy dissipation mechanism to solve the problems of insufficient energy dissipation capacity and short life of traditional dampers, thereby improving the energy dissipation efficiency and durability of the damper.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridge seismic isolation, and in particular relates to a staged variable stiffness viscous damper, an installation method thereof, and an application thereof. Background Art

[0002] Bridges are crucial hubs for road traffic. During earthquakes, major incidents such as beam collapse and excessive tilt can hinder rescue efforts and threaten lives and property. Therefore, maintaining bridge load-bearing capacity has become a key research area. In recent years, researchers both domestically and internationally have proposed structural control mechanisms, utilizing vibration damping devices to mitigate bridge response to earthquakes. As critical force-transmitting components, if the stiffness of the damping device is too high, it will not dissipate sufficient energy during an earthquake, potentially damaging the piers and beams. If the stiffness is too low, it will not provide sufficient rigidity, potentially causing beam collapse. Therefore, high performance requirements are placed on the damping device. The device must be able to dissipate shock (vibration) energy during both normal operation and during earthquakes, ensuring optimal bridge operation. Passive control technologies, such as friction damping and viscous damping, are currently widely used in bridge seismic isolation and provide high reliability.

[0003] Viscous dampers, widely used, offer excellent adaptability and high energy dissipation capabilities. However, these traditional dampers suffer from drawbacks such as potential failure under strong earthquakes, damage to the cylinder seal due to excessive seismic forces, inability to adjust damping, and a single energy dissipation method, all of which can severely damage bridges. To address these issues, a viscous damper with variable stiffness in stages is urgently needed. Summary of the Invention

[0004] Purpose of the invention: The present invention aims to address the shortcomings of the above-mentioned prior art and proposes a staged variable stiffness viscous damper and its installation method and application, which can provide sufficient vertical stiffness. The two-stage variable stiffness enables the damper to cope with strong earthquakes and prevent excessive pressure in the cylinder. The first spring group and the second spring group work in stages to achieve adaptive adjustment of the overall stiffness. The energy consumption efficiency is improved by utilizing multiple energy consumption mechanisms such as friction, elastic recovery, and throttling damping, and the damper has good seismic resistance.

[0005] Technical solution: In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0006] The present invention first provides a staged variable stiffness viscous damper, which includes an outer cylinder and a first inner cylinder and a second inner cylinder arranged inside the outer cylinder. A second piston is arranged inside the first inner cylinder, and a first piston is arranged inside the second inner cylinder. A piston rod penetrates the outer cylinder and passes through the insides of the second inner cylinder and the first inner cylinder to be connected to the second piston and the first piston. A structural disk is prefabricated on the piston rod in the middle of the first inner cylinder and the second inner cylinder. A group of force transmission rods are evenly arranged in the circumferential direction of the structural disk. Friction blocks are connected to both ends of the force transmission rods. Pads are respectively installed on the first inner cylinder and the second inner cylinder near the ends of the outer cylinder through pins. A first spring group is arranged between the friction block and the pad. Second spring groups are provided at the ends of the first inner cylinder and the outer cylinder and at the ends of the second inner cylinder and the outer cylinder. A friction damping module is also provided between the outer cylinder and the first inner cylinder and the second inner cylinder.

[0007] Furthermore, the friction damping module includes limiting slide rails respectively arranged on the inner wall of the outer cylinder body and the outer walls of the first inner cylinder body and the second inner cylinder body, and a friction plate is installed on the limiting slide rail, and the friction plate is in contact with the friction block.

[0008] Furthermore, the outer end of the piston rod and the outer end of the outer cylinder are both provided with connecting earrings.

[0009] Furthermore, the first inner cylinder and the second inner cylinder are filled with the same viscous fluid.

[0010] Furthermore, both the first piston and the second piston are provided with viscous fluid through holes.

[0011] Furthermore, a limiting ring is provided on the outside of the piston rod.

[0012] Furthermore, sealing rings are provided on both the first inner cylinder body and the second inner cylinder body at the locations where the piston rods penetrate.

[0013] The present invention also provides a method for installing the above-mentioned staged variable stiffness viscous damper, which comprises the following steps:

[0014] S11. Production and preparation of the piston rod, outer cylinder, limit rail, first inner cylinder, second inner cylinder, force transmission rod, friction plate, first spring group, second spring group, sealing ring, connecting earrings, viscous fluid, backing plate, limit ring, bayonet, friction block, first piston, second piston, structural disc;

[0015] S12. The prefabricated piston rod and the first piston and the second piston in the first inner cylinder and the second inner cylinder are connected and installed, filled with viscous fluid, the first piston and the second piston are adjusted to the center position of the second inner cylinder and the first inner cylinder, and the sealing ring is installed;

[0016] S13. Fix the friction plate to the limit rail, which is fixed to the outer side of the first inner cylinder, the second inner cylinder, and the inner side of the outer cylinder. Then, install the friction block at the end of the force transmission rod, and then install the outer cylinder. Adjust the position of the friction plate and the limit rail, and then install the first spring assembly, the pad, and the latch. Fix the first spring assembly to the friction block and the pad, ensuring that the two sides are symmetrical and free of prestress.

[0017] S14. Fix the second spring assembly to the bottom of the first inner cylinder, the second inner cylinder, and the cover plates at both ends of the outer cylinder, and then install the cover plates.

[0018] The present invention further provides an application of the above-mentioned staged variable stiffness viscous damper, which is installed between piers and beams or at both ends of a bridge to achieve the energy dissipation and shock absorption function of the bridge. Under normal working conditions and under earthquake action, relative displacement occurs between the piers and beams, and the piston rod is subjected to a reciprocating axial force.

[0019] Under normal use and earthquake protection conditions, the piston rod acts on the first and second pistons, and the friction plate and friction block undergo relative displacement, achieving dual energy dissipation through friction damping and throttling damping. The first spring group stores and transmits seismic energy. At this time, the first spring group is subjected to force acting on the bayonet pin, which is not damaged. This stage can effectively reduce bridge displacement and dissipate seismic energy.

[0020] When a rare earthquake occurs, the damper is subjected to a large seismic force, causing the pin to fail due to the force exceeding its bearing capacity, and the first spring group cannot continue to work. In this state, the first inner cylinder and the second inner cylinder are axially displaced under the action of the piston rod, and the second spring group is deformed. The damping stroke of the friction damping module increases, meeting the energy dissipation and shock absorption requirements under strong earthquakes. Beneficial effects

[0021] The main force-transmitting component of the present invention is a full-length piston rod. During the initial energy dissipation phase, or the first stage, a built-in first spring group provides initial stiffness. Energy is dissipated collaboratively using a composite mechanism of spring elastic recovery and throttling damping. The first spring stores energy, minimizing bridge deck lift under normal operating conditions and ensuring the normal use of the bridge. During small to medium earthquakes, the friction damping generated by the relative sliding of the friction module and the throttling damping energy dissipation mechanism generated by restricting fluid flow by the first and second pistons work together to significantly improve energy dissipation efficiency. The greater stiffness provided by the first spring group effectively prevents excessive pressure in the inner cylinder. Compared to traditional viscous dampers, the present invention effectively improves the damper's energy dissipation efficiency and significantly improves durability.

[0022] During the second stage of strong earthquake action, the latch fails and the first spring group no longer provides vertical stiffness. The second spring group provides vertical stiffness. At this time, the second spring group is the main source of stiffness, and the stiffness is relatively reduced. The seismic force borne by the bridge deck is relatively reduced, and the displacement of the piston rod is relatively increased. At this time, the energy consumption efficiency of the friction damping module is enhanced, and it has the ability of adaptive earthquake resistance, providing better energy consumption effect under strong earthquakes; the limit slide rail can limit the displacement of the piston rod within a certain range, preventing the piston rod from displacing too much and causing excessive displacement of the bridge deck.

[0023] 3. Due to the limited range of piston movement, the viscous damping module's energy dissipation capacity is insufficient under severe earthquakes. However, under strong earthquakes, the operating states of the different spring groups change, reducing the damper's overall stiffness. The relative movement of the inner and outer cylinders increases the friction damping stroke, resulting in improved damping capacity. Therefore, the present invention synergizes these two energy dissipation mechanisms to compensate for the shortcomings of the viscous damper, providing greater energy dissipation potential under severe earthquakes. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a cross-sectional view of a staged variable stiffness viscous damper;

[0025] Figure 2 for Figure 1 Cross-sectional view of AA;

[0026] Figure 3 for Figure 1 Cross-sectional view of the middle BB;

[0027] Figure 4 The figure is a schematic diagram of the installation position of a staged variable stiffness viscous damper of the present invention.

[0028] The accompanying drawings are as follows: piston rod 1, outer cylinder body 2, limiting slide rail 3, first inner cylinder body 4, second inner cylinder body 5, force transmission rod 6, friction plate 7, first spring group 8, second spring group 9, sealing ring 10, connecting earring 11, viscous fluid 12, backing plate 13, limiting ring 14, bayonet 15, friction block 16, first piston 17, second piston 18, structural disc 19. Implementation Method

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] Reference Figure 1-Figure 2 The cross-sectional view of a staged variable stiffness viscous damper constructed by the present invention includes a full-length piston rod 1 arranged in the center of the damper, a second piston 18 and a first piston 17 are respectively arranged in the first inner cylinder body 4 and the second inner cylinder body 5 and are fixedly connected to the piston rod 1, the piston rod 1 is fixedly connected to the structural disc 19, the end of the inner cylinder body is thicker than the two sides, the first inner cylinder body 4 and the second inner cylinder body 5 have the same size and initial relative position of the internal pistons; the force transmission rod 6 is a straight rod, one end of which is fixedly connected to the structural disc 19, and the other end is embedded in the friction block 16. When the piston rod 1 is displaced, the friction block 16 and the first spring group 8 produce the same displacement and deformation; the friction plate 7 is fixed on the limiting slide rail 3, and the friction block 16 and The friction plates 7 fit together, and the two undergo relative displacement during operation; the two ends of the first spring group 8 are respectively connected to the friction block 16 and the pad 13, and the pad 13 acts on the bayonet 15. The bayonet 15 is installed on the cylinder wall and is arranged on both sides of the pad 13 to limit the movement of the inner cylinder body and control the working state of the first spring group 8; the second spring group 9 is connected to the cavity at the end of the inner cylinder body and the outer cylinder body, and has no initial stress. When the bayonet 15 fails, the second spring group 9, as the main source of vertical stiffness, deforms under the action of the seismic force, and the first inner cylinder body 4 and the second inner cylinder body 5 undergo vertical displacement. The second spring group 9 stores seismic energy. At this time, the friction damping stroke is significantly increased, thereby improving the shock absorption and energy consumption performance of the damper. A friction plate 7 is mounted on the surface of the limiting guide rail 3 and fixed to the cylinder wall, limiting the maximum displacement of the piston rod and preventing the damper from failing due to excessive internal displacement. A cavity is retained between the first and second inner cylinders 4, 5, allowing the disc 19 to undergo axial displacement within the damper, ensuring that rigid-body collisions do not occur. The connecting earring 11 is slightly larger than the limiting ring 14 and the piston rod 1. The connecting earring 11 is prefabricated integrally with the connecting member to ensure its reliability. The limiting ring 14 is welded to its lower portion. A sealing ring 10 is provided where the piston rod 1 passes through the first and second inner cylinders 4, 5 to ensure the sealing of the viscous damper.

[0031] In this embodiment, the first inner cylinder 4 and the second inner cylinder 5 have the same size and are filled with the same viscous fluid. The design of the first spring assembly and the bayonet can be adjusted according to the additional stiffness required by the bridge.

[0032] Reference Figure 3 As a preferred embodiment, six springs are provided on one side of the first spring assembly 8, while the other side is symmetrically spaced perpendicular to the axis. A spacing is maintained between the first spring assembly 8 and the friction plate 7 to prevent collision during operation and maintain friction plate performance. The first and second inner cylinders 4 and 5 are fixedly connected to the limiting rails 3, with displacement limited by the limiting rails 3 and the limiting ring 14. Displacement is limited only in the axial direction, with no horizontal deviation perpendicular to the axis. The structural disk 19 is initially located in the center of the damper, and the force transmission rods 6 installed on both sides are of the same length and installed in the same position.

[0033] Reference Figure 4 After determining the dimensions based on actual project requirements, the damper is prefabricated in the factory. Once prefabricated, the damper is installed on-site. The installation method is as follows: bolts are used to secure the connecting earrings 11 on both sides of the pier. These are then hinged to the connecting earrings 11 at the bottom of the outer cylinder via rivets, completing the connection between the pier and the damper. After adjusting the piston rod to its initial preset position, the connecting earrings 11 at the bottom of the beam are positioned, installed, and riveted together to complete the connection between the beam and the damper. Under earthquake action, the beam and pier undergo relative displacement, achieving the purpose of energy dissipation and shock absorption through the damper.

[0034] It should be noted that when the elastic restoring force exerted by the first spring group 8 reaches a certain limit, the pin 15 on the same direction side will fail and the second spring group 9 will start to work. This state is the main change in the transition from the first stage to the second stage. In order to control the working performance of the damper, the stiffness of the first spring group 8, the second spring group 9 and the critical failure force of the pin can be selected according to actual engineering practice.

[0035] When the damper is in normal operation, the first spring group 8 primarily provides vertical stiffness, bearing the weight of the upper bridge and balancing uneven uplift of the bridge deck caused by traffic and construction. When the damper is subjected to small to moderate earthquakes, the piston rod 1 drives the force transmission rod 6, causing the friction module to generate frictional damping. This energy is stored through the first spring groups 8 on both sides, and the viscous damping module generates throttling damping, achieving dual-gain dissipation of seismic energy.

[0036] When the damper is subjected to a strong earthquake exceeding the designed earthquake, the latch 15 and the first spring group 8 fail due to the huge seismic force, and the first inner cylinder 4 and the second inner cylinder 5 are displaced. Due to the characteristic that the greater the throttling damping speed, the greater the damping force, the displacement of the inner cylinder can effectively reduce the internal pressure, maintain its working performance, and extend its working life; since the speed of the piston rod 1 is relatively high under strong earthquakes, the damping force of the viscous fluid becomes larger, and the vertical stiffness is mainly provided by the second spring group 9, the stiffness is relatively reduced, and the friction damping stroke is relatively increased, so the friction module can achieve a more efficient energy consumption effect.

[0037] It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention. Components not specified in this embodiment can be implemented using existing technologies.

Claims

1. A staged variable stiffness viscous damper, characterized by: The staged variable stiffness viscous damper comprises an outer cylinder (2) and a first inner cylinder (4) and a second inner cylinder (5) arranged inside the outer cylinder, a second piston (18) being arranged inside the first inner cylinder (4), a first piston (17) being arranged inside the second inner cylinder (5), a piston rod (1) penetrating the outer cylinder (2) and passing through the second inner cylinder (5) and the first inner cylinder (4) to be connected with the second piston (18) and the first piston (17), a structural disc (19) being prefabricated on the piston rod (1) between the first inner cylinder (4) and the second inner cylinder (5), the circumferential direction of the structural disc (19) being A group of force transmission rods (6) are evenly arranged, and friction blocks (16) are connected to both ends of the force transmission rods (6). Pads (13) are installed on the first inner cylinder (4) and the second inner cylinder (5) at positions close to the ends of the outer cylinder (2) through bayonets (15). A first spring group (8) is arranged between the friction blocks (16) and the pads (13). A second spring group (9) is arranged between the ends of the first inner cylinder (4) and the outer cylinder (2) and between the ends of the second inner cylinder (5) and the outer cylinder (2). A friction damping module is also arranged between the outer cylinder (2) and the first inner cylinder (4) and the second inner cylinder (5).

2. The staged variable stiffness viscous damper according to claim 1, characterized in that: The friction damping module comprises limiting slide rails (3) respectively arranged on the inner wall of the outer cylinder (2) and the outer walls of the first inner cylinder (4) and the second inner cylinder (5); a friction plate (7) is mounted on the limiting slide rail (3); and the friction plate (7) is in contact with the friction block (16).

3. The staged variable stiffness viscous damper according to claim 1, characterized in that: The outer end of the piston rod (1) and the outer end of the outer cylinder (2) are both provided with connecting earrings (11).

4. The staged variable stiffness viscous damper according to claim 1, characterized in that: The first inner cylinder (4) and the second inner cylinder (5) are filled with the same viscous fluid (12).

5. The staged variable stiffness viscous damper according to claim 1, characterized in that: The first piston (17) and the second piston (18) are both provided with viscous fluid through holes.

6. The staged variable stiffness viscous damper according to claim 1, characterized in that: A limiting ring (14) is provided on the outside of the piston rod (1).

7. The staged variable stiffness viscous damper according to claim 1, characterized in that: The first inner cylinder body (4) and the second inner cylinder body (5) are both provided with sealing rings (10) at the locations where the piston rod (1) passes through.

8. A method for installing the staged variable stiffness viscous damper according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S11. Fabricate and prepare the piston rod (1), the outer cylinder (2), the limiting slide rail (3), the first inner cylinder (4), the second inner cylinder (5), the force transmission rod (6), the friction plate (7), the first spring group (8), the second spring group (9), the sealing ring (10), the connecting earring (11), the viscous fluid (12), the backing plate (13), the limiting ring (14), the bayonet (15), the friction block (16), the first piston (17), the second piston (18), and the construction disc (19); S12. The piston rod (1) prefabricated integrally with the structural disc (19) is connected and installed with the first piston (17) and the second piston (18) in the first inner cylinder (4) and the second inner cylinder (5), filled with viscous fluid, and the first piston (17) and the second piston (18) are adjusted to the center position of the second inner cylinder (5) and the first inner cylinder (4), respectively, and the sealing ring (10) is installed; S13. Fix the friction plate (7) on the limiting slide rail (3), and the limiting slide rail (3) is fixed to the outer side surfaces of the first inner cylinder (4), the second inner cylinder (5) and the inner side surface of the outer cylinder (2), then install the friction block (16) at the end of the force transmission rod (6), and then install the outer cylinder (2). After adjusting the position of the friction plate (7) and the limiting slide rail (3), install the first spring group (8), the pad (13) and the bayonet (15), and fix the first spring group (8) on the friction block (16) and the pad (13) to ensure that the structures on both sides are symmetrical and there is no prestress; S14. Fix the second spring assembly (9) to the bottom of the first inner cylinder (4), the second inner cylinder (5) and the cover plates at both ends of the outer cylinder (2), and then install the cover plates.

9. An application of the staged variable stiffness viscous damper according to any one of claims 1 to 7, characterized in that: The staged variable stiffness viscous damper is installed between the piers and beams or at both ends of the bridge to realize the energy dissipation and shock absorption function of the bridge. Under normal working conditions and earthquake action, relative displacement occurs between the piers and beams, and the piston rod (1) is subjected to a reciprocating axial force. Under normal use and earthquake protection conditions, the piston rod (1) acts on the first piston (17) and the second piston (18), and the friction plate (7) and the friction block (16) are relatively displaced, thereby realizing the dual efficiency-enhancing energy consumption of friction damping and throttling damping. The first spring group (8) stores and transmits earthquake energy. At this time, the first spring group is subjected to force acting on the latch (15), and the latch (15) is not damaged. At this stage, the bridge displacement can be effectively reduced and the earthquake energy can be dissipated. When a rare earthquake occurs, the damper is subjected to a large earthquake force, causing the pin (15) to be subjected to a force exceeding its bearing capacity and fail, and the first spring group cannot continue to work. In this state, the first inner cylinder (4) and the second inner cylinder (5) are displaced axially under the action of the piston rod (1), and the second spring group (9) is deformed, and the damping stroke of the friction damping module is increased, thereby meeting the energy dissipation and shock absorption requirements under strong earthquakes.

Images