Gear pendulum damping system for preventing bridge from falling off

Abstract

The gear pendulum damping system comprises a rack and a gear pendulum assembly, and teeth of the rack are downwards fixed to the bottom of a bridge body of the bridge; the gear swing assembly comprises a gear, a swing arm fixedly connected with the gear and extending downwards, and a mass block fixed to the lower portion of the swing arm. The gear is meshed with the rack and rotationally matched and supported on the pier; a lever type simple pendulum mechanism is formed, when the beam body moves backwards, the gear is driven by the rack to rotate, so that the swing arm and the mass block are driven to swing by a certain height, by means of the amplification characteristic of the lever, several times of acting force of the mass block acts on the rack through the gear, and therefore the beam body is prevented from moving, and after displacement is generated in time, the beam body is prevented from moving. And the overall structure is simple and compact, mounting and dismounting are convenient, and the manufacturing, using and maintaining cost is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bridge safety systems, in particular to a gear pendulum damping system for preventing beam falling of a bridge. BACKGROUND

[0002] The main beam displacement and beam falling of a bridge in an earthquake are the main phenomena causing safety problems in the bridge epicenter. In view of this damage mode, various types of damping and isolation devices have appeared, hoping to prevent or slow down the displacement of the bridge and the occurrence of beam falling under the condition of earthquake and the like.

[0003] In the prior art, devices for actively preventing displacement or beam falling are usually used, such as energy dissipation devices, viscous dampers, viscoelastic dampers, electrorheological dampers, magnetorheological dampers, and metal dampers (such as soft steel dampers, lead dampers, memory alloy dampers, and restrained buckling braces, etc.). These devices prevent the displacement of the main beam and the beam falling by actively resisting, and require a large resistance, which requires a large volume of the device, and occupies a large space on the bridge. The above devices generally have high requirements for the performance of the base material and complex structure, and the components are generally non-standardized, making manufacturing, processing and assembly difficult. For example, soft steel dampers, lead rubber bearings, and oil dampers, etc. have high costs of equipment materials, manufacturing and installation. Maintenance and repair are difficult, such as soft steel dampers and lead core dampers, which often need to be installed at the support position and bear a large vertical structural gravity load during normal use. The installation position is narrow, and the maintenance and replacement require a large amount of upper structure to be jacked up, which is difficult to operate and has high cost. In addition, the performance state and aging degradation of the damping facility during the use period are difficult to detect and know. Moreover, the function is relatively single, and general damping facilities are only sensitive to a single motion variable, such as displacement, velocity or acceleration. The effectiveness of damping is limited, such as the relative motion displacement reaction is reduced, the acceleration reaction and inertial force are increased, and it is difficult to achieve a more balanced and ideal damping effect. Finally, the reset effect of the main structure is generally poor. Except for the friction pendulum bearing which has a certain reset effect on the upper structure, other damping facilities are difficult to restore the upper structure to the original design position when the upper structure has a large relative horizontal displacement relative to the lower structure after an earthquake, which leads to difficulties in restoring the use function of the main structure after the earthquake.

[0004] Meanwhile, a common method to eliminate or reduce vibration is to use tuned mass dampers. The principle of vibration reduction is that when the main structure vibrates, the tuned mass damper vibrates relative to the main structure. The inertial force generated by the relative vibration of the tuned mass damper then acts back on the structure, thereby suppressing the vibration of the main structure. However, this structure only uses inertia to prevent the main structure from swaying. It can play a corresponding role in the main structure of buildings such as buildings. However, in order to prevent the movement of beams and the falling of beams, the damping effect relies on inertia, which has the problems of delay and insufficient force, resulting in an insignificant effect.

[0005] Therefore, it is necessary to improve existing devices for preventing beam movement and beam collapse during natural disasters such as earthquakes. The improved devices should have a simple and compact structure, be suitable for bridge use without occupying a large space, effectively prevent beam movement and collapse, have good resetting characteristics, and have low manufacturing, maintenance, and usage costs. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to overcome the defects in the prior art, with a simple and compact structure, suitable for use in bridges without occupying a large space, effectively preventing beam movement and beam drop, having good reset characteristics, and low manufacturing, maintenance and use costs.

[0007] The present invention provides a gear pendulum shock absorption system for preventing bridge beams from falling off, comprising a rack and a gear pendulum assembly, wherein the teeth of the rack are fixed downward to the bottom of the bridge beam; the gear pendulum assembly comprises a gear, a pendulum arm fixedly connected to the gear and extending downward, and a mass block fixed to the lower part of the pendulum arm.

[0008] The gear meshes with the rack and rotates to support the bridge pier.

[0009] Furthermore, the rack is arranged along the longitudinal and / or transverse direction of the beam, and its position corresponds to the side of the pier; the central axis of the gear is located near the vertical centerline of the corresponding side of the pier.

[0010] Furthermore, the rack is fixed to a rack base pre-embedded in the beam body;

[0011] The gear pendulum assembly also includes a gear shaft, and the gear is rotatably engaged with the gear shaft at a predetermined position on the bridge pier.

[0012] Furthermore, the rack base is a steel plate or bracket pre-embedded in the bottom of the beam, and the rack is welded to the steel plate or bracket;

[0013] The gear shaft is fixed to the bridge pier, and the gear is rotatably engaged with the gear shaft.

[0014] Furthermore, the radius of the gear is r; r > 200mm + a, where a is the distance from the bottom surface of the beam to the top surface of the pier.

[0015] Furthermore, the distance from the rotation center of the gear to the center of mass of the mass block is more than 1 times the radius of the gear;

[0016] The ratio of the mass of the mass block to the mass of the beam is generally between 1% and 10%.

[0017] Furthermore, the beam is supported on the pier by rubber bearings.

[0018] Furthermore, there are at least two racks, respectively arranged in the longitudinal and transverse directions of the beam, and the racks are positioned such that the corresponding gear pendulum assembly is located on the side of the pier.

[0019] Furthermore, the gear shaft is pre-embedded in the bridge pier and fixed to the frame inside the bridge pier.

[0020] Furthermore, the width of the rack is greater than the width of the gear, and under normal conditions, the gear is located in the middle of the rack and meshes with it.

[0021] The beneficial effects of the present invention are as follows: The gear pendulum shock absorption system for preventing bridge beams from falling disclosed in the present invention adopts a gear and rack meshing structure combined with a pendulum arm and a mass block to form a lever-type single pendulum mechanism. When the beam moves backward, the rack drives the gear to rotate, thereby causing the pendulum arm and mass block to swing to a certain height. By utilizing the amplification characteristic of the lever, the force of the mass block is several times that of the rack through the gear, thereby preventing the beam from moving. Even if displacement occurs, it is easy to reset under the action of the lever force.

[0022] This invention features a simple and compact overall structure, convenient installation and disassembly, and is suitable for bridge use without occupying a large space. It effectively prevents beam movement and beam drop. The gear pendulum damping system can be made of standardized and inexpensive conventional steel. During use, it provides good and balanced damping. The gear pendulum is sensitive to the relative displacement and relative acceleration between the beam and the pier, and can simultaneously reduce and suppress adverse displacement and acceleration of the superstructure. While reducing the risk of beam / roof truss drop, it also reduces the adverse acceleration response and inertial force of the structure. The mechanical principle of the lever structure is simple and direct, and the force transmission is accurate and reliable. The system design parameters have a large adjustment range, making the design and implementation more flexible, and the damping effect meets the design objectives.

[0023] This invention is convenient to manufacture, use, maintain, and repair. When in use, the invention is installed outside the support gap space, and the main functional components are all exposed, which facilitates direct observation of the appearance of the components on both sides and the implementation of maintenance such as oiling and anti-corrosion. In addition, except for the pre-embedded rotating shaft, the other components can be easily replaced as needed. During use, it has an unconventional reset function. This invention has the natural advantage of a pendulum relying on the gravity of the pendulum mass to reset. At the same time, it can also use the mass block-pendulum arm-gear-rack to drive the upper structure to return from the offset position to the original design position after an earthquake. If necessary, manual external assistance can be applied to the pendulum mass block to help the pendulum mass block and the upper structure reset. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0025] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0026] like Figure 1 As shown, the gear pendulum shock absorption system for preventing bridge beams from falling off according to the present invention includes a rack 3 and a gear pendulum assembly 4. The teeth of the rack 3 are fixed downward to the bottom of the bridge beam 1. The gear pendulum assembly 4 includes a gear 401, a pendulum arm 402 fixedly connected to the gear 401 and extending downward, and a mass block 403 fixed to the lower part of the pendulum arm.

[0027] The gear 401 meshes with the rack 3 and rotates to support the pier 2. In this embodiment, a bridge and a pier are used for illustration, but the present invention can obviously be applied to a structure in which the lower structure supports the upper structure, which will not be described in detail here.

[0028] In this structure, the rack 3 is usually fixed to the beam by using a pre-embedded seat, and the rack is fixed to the pre-embedded seat. This can be done by welding or detachable connection, etc. The direction of the rack is generally located in the longitudinal and transverse directions of the beam. The direction of beam movement or beam collapse during an earthquake will not be elaborated here.

[0029] Similarly, the gear can be supported on the pier 2 in various ways, but a gear shaft should be fixedly installed to support the gear, and the swing arm 402 should be fixed to the gear. The method can be welding or detachable connection. It needs to have the strength to support the mass block to form a swing, which will not be elaborated here.

[0030] The mass block 403 generally adopts a disc-shaped structure to avoid swing interference; there are various ways to fix it to the swing arm, such as welding and detachable connection, which will not be elaborated here.

[0031] In this embodiment, the rack 3 is arranged along the longitudinal and / or transverse direction of the beam 1, and its position corresponds to the side of the pier 2, as shown in the figure. The rack 3 can be arranged only in the transverse direction, only in the longitudinal direction, or both. The side of the pier refers to the longitudinal side or the transverse side, which will not be elaborated here. The central axis of the gear 401 is located near the vertical center line of the corresponding side of the pier 2. If the pier is cylindrical, the central axis of the gear 401 should be located near the vertical center line in the longitudinal and transverse directions relative to the beam to ensure sufficient meshing swing space.

[0032] In this embodiment, the rack 3 is fixed to the rack base pre-embedded in the beam body. The structure of the rack base is not limited or described here, as long as it can be used for fixed welding or detachable installation of the rack. It will not be described in detail here.

[0033] The gear pendulum assembly 4 also includes a gear shaft 404. The gear 401 is rotatably fitted to a predetermined position on the pier 2 via the gear shaft 404. The predetermined position refers to the position where it can mesh with the rack and is near the aforementioned vertical center line, which will not be elaborated here. There are various ways to set the gear shaft 404. It can be that a gear shaft seat is fixedly set on the pier 2, and the gear shaft 404 can be rotatably or fixedly set on the gear shaft seat. The gear is fixedly or rotatably set on the gear shaft, which will not be elaborated here.

[0034] In this embodiment, the rack base is a steel plate or bracket pre-embedded in the bottom of the beam, and the rack is welded to the steel plate or bracket. In this embodiment, a steel plate is used as the rack base (not marked in the figure, but the structure of the pre-embedded steel plate is a structure well known in the art). Of course, it can also be set as a bracket structure, which can also achieve the purpose of the invention.

[0035] The gear shaft 404 is fixed to the pier 2, and the gear 401 rotates with the gear shaft 404. The gear shaft can be set in various ways, such as a structure with the middle section pre-embedded in the middle section and extending out at both ends of the pier, or a gear can be rotatably set at both ends (usually through rolling bearings or sliding bearings). Of course, racks can be set on both sides, which has good connection stability and balance. The middle section of the gear shaft is welded to the frame of the pier to ensure its firmness.

[0036] In this embodiment, the radius of the gear is r; r > 200mm + a, where a is the distance from the bottom surface of the beam to the top surface of the pier; the gear of this size has sufficient load-bearing capacity and does not occupy too much bridge space.

[0037] In this embodiment, the distance from the rotation center of the gear to the center of mass of the mass block is more than 1 times the radius of the gear. In this structure, in order to achieve the best coordination between the gear radius and the length of the connecting piece, if the gear is too small, the inertial force will be insufficient; if the gear is too large, the rotation angle will be too large and too much swing arm length will be occupied, which is not conducive to the shock absorption and limiting effect of the gear swing arm. The distance from the rotation center of the gear to the center of mass of the mass block is related to the length of the swing arm. The specific ratio of this dimension to the gear radius is determined according to the bridge shock absorption design calculation. The stronger the seismic resistance, the longer the swing arm should be. This will not be elaborated here.

[0038] The ratio of the mass of the mass block to the mass of the beam is generally between 1% and 10%.

[0039] In this embodiment, the distance from the rotation center of the gear 401 to the center of mass of the mass block 403 (i.e., the connection length of the swing arm) is 1.0-1.5 times the radius of the gear 401, and in this embodiment it is 105 times.

[0040] The mass of the mass block 403 is 1-10% of the mass of the beam. In this embodiment, 5% is used. Generally, the larger the mass ratio, the more obvious the shock absorption effect, but the cost, space and bridge load are also greater. The specific appropriate value is determined according to the bridge shock absorption design calculation. Due to the leverage amplification effect of the present invention, according to the seismic design, the mass of the mass block 403 can be selected as a smaller proportion to save costs and make the overall structure lightweight.

[0041] In this embodiment, the beam is supported on the pier 2 by rubber bearings 5. The rubber bearings 5 ​​are the most commonly used type of seismic isolation bearings. They can ensure vertical stiffness and bearing capacity, and can also significantly reduce horizontal stiffness, so as to ensure that the present invention can effectively prevent movement and beam drop, and facilitate repositioning. This embodiment uses a laminated rubber bearing.

[0042] In this embodiment, there are at least two racks, which are respectively arranged in the longitudinal and transverse directions of the beam. The racks are arranged such that the corresponding gear pendulum assembly is located on the side of the pier, which can prevent the beam 1 from slipping or falling off in both the transverse and longitudinal directions.

[0043] In this embodiment, the gear shaft 404 is pre-embedded in the pier 2 and fixed to the frame inside the pier 2, generally by welding, forming an integral whole with the pier, which helps to ensure that the invention forms a stable swing and reset.

[0044] In this embodiment, the width of the rack 3 is greater than the width of the gear 401. Under normal conditions, the gear 401 is located in the middle of the rack 3 and meshes with it. Generally, this means that it is located near the midpoint of the longitudinal and transverse directions, which can be understood as near the geometric center. This allows the gear to maintain meshing even when the rack undergoes a large displacement under the drive of the beam, and prevents displacement and beam drop from occurring.

[0045] This invention was verified through 25 experiments. Field measurements simulating earthquakes with different acceleration inputs showed that this invention effectively reduces the acceleration and displacement of the bridge beam model, thus achieving the purpose of vibration reduction and limiting. Analysis of the maximum acceleration and displacement revealed the following effects: Acceleration suppression effect at the beam end: After installing the system of this invention, the maximum acceleration response at the beam end was reduced by 25.6% compared to before installation; Relative displacement suppression effect between the beam end and the pier top: After installing the system of this invention, the maximum relative displacement response at the beam end was reduced by 30% compared to before installation.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A gear pendulum damping system for preventing the falling of a bridge beam, characterized by: The rack is fixed to the bottom of the beam body of the bridge, and the gear swing assembly comprises a gear, a swing arm fixedly connected with the gear and extending downward, and a mass fixed to the lower part of the swing arm. The gear is engaged with the rack and supported on the pier in a rotating manner.

2. The gear pendulum damping system for preventing the falling of the bridge beam according to claim 1, characterized in that: The rack is arranged along the longitudinal direction and / or the transverse direction of the beam body and positioned corresponding to the side of the pier.

3. The gear pendulum damping system for preventing the falling of the bridge beam according to claim 1, characterized in that: The rack is fixed to the rack base pre-embedded in the beam body. The gear swing assembly further comprises a gear shaft, and the gear is arranged at a specified position of the pier in a rotating manner through the gear shaft.

4. The gear pendulum damping system for preventing the falling of the bridge beam according to claim 3, characterized in that: The rack base is a steel plate or bracket pre-embedded in the bottom of the beam body, and the rack is welded to the steel plate or bracket. The gear shaft is fixed to the pier, and the gear is in rotating fit with the gear shaft.

5. The gear pendulum damping system for preventing the falling of the bridge beam according to claim 1, characterized in that: The radius of the gear is r, and r>200mm+a, wherein a is the distance from the bottom surface of the beam body to the top surface of the pier.

6. The gear pendulum damping system for preventing the falling of the bridge beam according to claim 2, characterized in that: The distance from the rotation center of the gear to the center of mass of the mass is more than 1 times the radius of the gear. The mass ratio of the mass of the mass to the mass of the beam body is generally 1-10%.

7. The gear pendulum damping system for preventing the falling of the bridge beam according to claim 2, characterized in that: The beam body is supported on the pier through a rubber support.

8. The gear pendulum damping system for preventing the falling of the bridge beam according to claim 7, characterized in that: The rack is at least two, corresponding to the longitudinal and transverse directions of the beam body, and arranged at positions such that the corresponding gear swing assemblies are located on the corresponding sides of the pier.

9. The gear pendulum damping system for preventing the falling of the bridge beam according to claim 8, characterized in that: The gear shaft is pre-embedded in the pier and fixed with the framework in the pier.

10. The gear pendulum damping system for preventing the falling of the bridge beam according to claim 9, characterized in that: The width of the rack is greater than the width of the gear, and the gear is normally located in the middle of the rack and engaged with the rack.

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