Anti-shrinkage test model single and double direction displacement restriction universal type friction pendulum bearing

Abstract

The application discloses a general type friction pendulum bearing for anti-shrinkage scale test model single-direction displacement restriction, which comprises an upper bearing plate, a friction plate, a damping ball pendulum, a lower bearing plate, a limiting screw, a reserved bolt and the like. The upper bearing plate and a main beam are connected together through the upper reserved bolt, and the friction plate is embedded in the friction surface of the upper bearing plate. Then, the damping ball pendulum and the lower bearing plate with the polytetrafluoroethylene friction plate embedded are placed in the corresponding positions, and the lower bearing plate is connected with a pier column through the lower reserved bolt. The curvature radius, bearing design displacement and bearing yield displacement and other design parameters of the friction pendulum bearing are determined based on the concept of the similar period and stiffness of the shaking table experiment and the real bridge isolation structure. The longitudinal and lateral limiting of the friction pendulum bearing can be realized by changing the screwing length of the limiting screw, and the quick conversion between the two-way movable bearing, the single-way movable bearing and the fixed bearing can be realized. The limiting can be quickly realized through the limiting screw, the operation is simple, and the bearing type conversion is convenient.

Description

Technical Field

[0001] This invention relates to the field of bridge bearing technology, and in particular to a general-purpose friction pendulum bearing for single and two-way displacement constraint in a seismic scale test model. Background Technology

[0002] To improve the seismic performance of bridge structures and ensure the safety of life and property, seismic isolation technology has become an effective protective measure in high-intensity seismic areas. Friction pendulum bearings, with their large vertical bearing capacity, simple structure, good durability, and wide applicability, are widely used in bridge seismic design. To clarify the structural response of actual bridge structures under seismic loads, shaking table tests are needed to obtain experimental data and analyze the actual structural response. However, due to limitations in test sites, funding, and facilities, scaled-down models are often used for testing, meaning the test model's dimensions are strictly reduced relative to the prototype structure at a fixed ratio. To ensure that the seismic system period and stiffness of the scaled-down bridge model are equivalent to the actual structure, the actual bridge friction pendulum bearings need to be scaled down to an equivalent scale, while maintaining the same bearing type as the original bridge. However, the actual bridge friction pendulum bearings are relatively large; simply scaling them down to the superstructure ratio to obtain the test model bearings does not guarantee complete equivalence to the original structure. Furthermore, the scaled-down dimensions of the actual bridge friction pendulum bearings are small, making bearing fabrication difficult. Furthermore, it is necessary to ensure that the actual bridge bearing type is consistent with the test model bearing type, i.e., fixed bearing, unidirectional movable bearing, or bidirectional movable bearing. Actual bridge friction pendulum bearings often use pins to initially limit the bearing position, and then shear the pins after the seismic acceleration increases to ensure the friction surface effectively dissipates energy. However, using pins for friction pendulum bearings in scaled-down model tests not only makes it difficult to determine the shear load but also hinders bearing fabrication. Therefore, a simple friction pendulum bearing suitable for shaking table tests on scaled-down bridge models needs to be designed. Summary of the Invention

[0003] The purpose of this invention is to provide a universal friction pendulum support for single and two-way displacement constraints in a seismic scaled-down test model, thereby solving the problems existing in the background art.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] This invention provides a universal friction pendulum support for a seismic scale test model with single and double displacement constraints, comprising an upper support plate and a lower support plate, and a shock-absorbing ball pendulum that is limited between the upper support plate and the lower support plate.

[0006] The upper support plate has a sliding arc groove at the bottom that contacts the upper surface of the shock-absorbing ball pendulum, and the lower support plate has a sliding arc groove at the top that contacts the lower surface of the shock-absorbing ball pendulum.

[0007] An upper support plate wall is provided on the upper support plate flat plate, which surrounds the outer periphery of the shock-absorbing ball pendulum; a plurality of limiting screws extending toward the outer wall of the sliding arc groove of the lower support plate are symmetrically provided on the upper support plate wall.

[0008] Furthermore, friction plates that are in close contact with the shock-absorbing ball pendulum are respectively provided in the sliding arc groove of the upper support plate and the sliding arc groove of the lower support plate;

[0009] Or / and, the friction plate is made of polytetrafluoroethylene.

[0010] Furthermore, the upper support plate enclosure is a regular polygonal structure.

[0011] Furthermore, the upper support plate has pre-drilled holes at its corners, and pre-drilled bolts are installed in the pre-drilled holes.

[0012] Or / and, the reserved hole in the upper support is a vertically arranged threaded hole.

[0013] Furthermore, lower support reserved holes are respectively opened at the corners of the lower support plate, and lower support plate reserved bolts are installed in the lower support reserved holes; in use, the lower end of the upper support plate reserved bolt is fixedly connected to the upper end of the lower support plate reserved bolt.

[0014] Or / and, the reserved hole of the lower support is a vertically arranged threaded hole.

[0015] Furthermore, the upper support plate sliding arc groove and the lower support plate sliding arc groove have the same radius of curvature.

[0016] Furthermore, the design method for friction pendulum supports:

[0017] Based on the concept of similarity in period and stiffness between shaking table experiments and actual bridge seismic isolation structures, the design parameters of the friction pendulum support curvature radius, support design displacement, and support yield displacement are determined:

[0018] Step 1: Determine three controllable similarity constants based on the structural test site and shaking table performance parameters, namely the length similarity constant S. l Stress similarity constant S σ acceleration similarity constant S a .

[0019] Step 2: Referencing the arrangement of seismic isolation bearings in the prototype structure, determine the equivalent number and location of seismic isolation bearings for the experimental structure.

[0020] Step 3: Based on the equation analysis method and the dimensional analysis method, the similarity equation (1) that the physical quantity similarity constants of the structural shaking table test dynamics problem must satisfy is derived:

[0021]

[0022] In equation (1), S E S represents the similarity coefficient of elastic modulus; m S represents the quality similarity coefficient; a S represents the acceleration similarity coefficient; l Let represent the length similarity coefficient. Equation (1) is further derived into Equation (2), that is...

[0023]

[0024] In equation (2), S K Indicates the stiffness similarity coefficient;

[0025] Step 4: Determine the initial stiffness of the experimental scaled support parameters according to the principle of stiffness similarity:

[0026]

[0027] Stiffness after yielding:

[0028] Equivalent stiffness:

[0029] For the supports of the model structure, their stiffness satisfies the similarity relation:

[0030] K m =S K ·K p Equation (6)

[0031] In the formula: K1 represents the initial stiffness; μ represents the support friction coefficient; W represents the vertical load; D y K represents the yield displacement; K2 represents the post-yield stiffness; R represents the support curvature radius; K eff Indicates equivalent stiffness; D d Indicates the design displacement of the support; K m and K p These represent the support stiffness of the scaled-down model and the original model, respectively. Where: the superscript m (model) represents the parameters of the scaled-down model, and p (prototype) represents the parameters of the original model.

[0032] From equations (3) and (6), we get:

[0033] From equations (4) and (6), we get:

[0034] From equations (5) and (6), we get:

[0035] Step 5: Design and manufacture the scaled-down friction pendulum support based on the above calculation parameters.

[0036] Compared with existing scaled-down model friction pendulum supports for seismic testing, this invention has the following characteristics:

[0037] 1) Simple construction. The friction pendulum support proposed in this invention consists only of upper and lower support plates, a shock-absorbing ball pendulum, and other structures, achieving basic functions through a simple structure; it is easy to install, and the diameter of the pre-drilled bolt holes is larger than that of the pre-embedded bolts, allowing for a certain degree of installation tolerance. Based on this, this invention can be mass-produced for use in seismic tests of scaled-down models.

[0038] 2) Quick and easy positioning. Traditional friction pendulum supports achieve positioning by using pins; however, the shear load of these pins is difficult to determine in seismic tests. This invention achieves positioning in different directions by using positioning screws: the positioning screw is screwed onto the screw hole in the direction where positioning is needed, and the allowable displacement of the support can be set by controlling the screw's screw insertion length; the screw is removed when positioning is not needed. Operation is quick and convenient, especially suitable for seismic tests of scaled-down models. Attached Figure Description

[0039] The present invention will be further described below with reference to the accompanying drawings.

[0040] Figure 1 This is a three-dimensional overall structural diagram of the present invention;

[0041] Figure 2 This is a three-dimensional structural diagram of the upper support plate of the present invention;

[0042] Figure 3 This is a three-dimensional structural diagram of the lower support plate of the present invention;

[0043] Figure 4 This is a front sectional view of the present invention;

[0044] Figure 5 This is a top view of the upper support plate;

[0045] Figure 6 This is a top view of the lower support plate.

[0046] The reference numerals in the diagram are as follows: 1-Pre-reserved bolts for the upper support plate; 11-Pre-reserved holes for the upper support; 2-Flat plate for the upper support plate; 3-Wall plate for the upper support plate; 4-Limit screw; 5-Pre-reserved bolts for the lower support plate; 51-Pre-reserved holes for the lower support; 6-Flat plate for the lower support plate; 7-Sliding arc groove for the upper support plate; 8-Sliding arc groove for the lower support plate; 9-PTFE friction plate; 10-Shock-absorbing ball pendulum. Detailed Implementation

[0047] This embodiment discloses a design method for a general-purpose friction pendulum support with unidirectional and bidirectional displacement constraints, which mainly involves the design parameters and design details of the friction pendulum support.

[0048] This invention determines design parameters such as the radius of curvature, design displacement, and yield displacement of the friction pendulum support based on the concept of similarity between the period and stiffness of shaking table experiments and actual bridge seismic isolation structures.

[0049] Step 1: Determine three controllable similarity constants based on the structural test site and shaking table performance parameters, namely the length similarity constant S. l Stress similarity constant S σ acceleration similarity constant S a .

[0050] Step 2: Referencing the arrangement of seismic isolation bearings in the prototype structure, determine the equivalent number and location of seismic isolation bearings for the experimental structure.

[0051] Step 3: Based on the equation analysis method and the dimensional analysis method, the similarity equation (1) that the physical quantity similarity constants of the structural shaking table test dynamics problem must satisfy is derived:

[0052]

[0053] In equation (1), S E S represents the similarity coefficient of elastic modulus; m S represents the quality similarity coefficient; a S represents the acceleration similarity coefficient; l Let represent the length similarity coefficient. Equation (1) is further derived into Equation (2), that is...

[0054]

[0055] In equation (2), S K Indicates the stiffness similarity coefficient;

[0056] Step 4: Determine the initial stiffness of the experimental scaled support parameters according to the principle of stiffness similarity:

[0057]

[0058] Stiffness after yielding:

[0059] Equivalent stiffness:

[0060] For the supports of the model structure, their stiffness satisfies the similarity relation:

[0061] K m =S K ·K p Equation (6)

[0062] In the formula: K1 represents the initial stiffness; μ represents the support friction coefficient; W represents the vertical load; D y K represents the yield displacement; K2 represents the post-yield stiffness; R represents the support curvature radius; K eff Indicates equivalent stiffness; D d Indicates the design displacement of the support; K m and K p These represent the support stiffness of the scaled-down model and the original model, respectively. Where: the superscript m (model) represents the parameters of the scaled-down model, and p (prototype) represents the parameters of the original model.

[0063] From equations (3) and (6), we get:

[0064] From equations (4) and (6), we get:

[0065] From equations (5) and (6), we get:

[0066] Step 5: Design and manufacture the scaled-down friction pendulum support based on the above calculation parameters.

[0067] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments:

[0068] This embodiment provides a universal friction pendulum support for a seismic scale-down test model with single and double displacement constraints, including an upper support plate 2 and a lower support plate 6, and a shock-absorbing ball pendulum 10 that is limited and installed between the upper support plate 2 and the lower support plate 6; wherein an upper support plate sliding arc surface groove 7 is formed at the bottom of the upper support plate 2, which contacts the upper surface of the shock-absorbing ball pendulum 10, and a lower support plate sliding arc surface groove 8 is formed at the top of the lower support plate 6, which contacts the lower surface of the shock-absorbing ball pendulum 10; an upper support plate surrounding wall plate 3 is provided on the upper support plate 2, surrounding the outer periphery of the shock-absorbing ball pendulum 10; and a plurality of limiting screws 4 extending to the outer wall of the lower support plate sliding arc surface groove 8 are symmetrically installed on the upper support plate surrounding wall plate 3.

[0069] In specific implementation, it includes: a sliding cavity is formed between the upper support plate 2 and the lower support plate 6, and the sliding arc surface groove 7 of the upper support plate and the sliding arc surface groove 8 of the lower support plate cooperate to form a sliding cavity for limiting the installation of the shock-absorbing ball pendulum;

[0070] Specifically, the outer steel enclosure 3 on the upper support plate 2 serves as a sealing component to reduce the contamination and damage of the sliding cavity by the external environment; the sealing component is the outer steel enclosure 3 of the upper support plate 2, which plays a sealing role to reduce the contamination and damage of the sliding cavity by the external environment.

[0071] In this embodiment, friction plates 9 that are in close contact with the shock-absorbing ball pendulum 10 are respectively installed in the sliding arc groove 7 of the upper support plate and the sliding arc groove 8 of the lower support plate; wherein the friction plates 9 can be made of polytetrafluoroethylene material.

[0072] In this embodiment, the upper support plate enclosure 3 is a regular polygonal structure, and the upper support plate enclosure 3 is an octagonal fence structure, such as... Figure 1 As shown, a screw hole is made on each of the short side wall plates at the corresponding positions of the four sides of the upper support plate 2 for installing limit screws. When it is necessary to limit the displacement in a certain direction, the limit screw is screwed into the two screw holes opposite to that direction. The calculated allowable displacement of the support can be achieved by controlling the screw screw insertion length. When the limit is not needed, the limit screw can be removed. In this way, the single and double bidirectional limit of the support can be achieved.

[0073] In this embodiment, the upper support plate 2 has upper support reserved holes 11 at its corners, and upper support plate reserved bolts 1 are installed in the upper support reserved holes 11; in specific implementation, the upper support reserved holes 11 are vertically threaded holes; the upper end of the upper support plate reserved bolts 1 is fixedly connected to the bottom of the bridge beam through anchor sleeve assembly and limit bolt assembly.

[0074] Lower support reserved holes 51 are respectively opened at the corners of the lower support plate 6, and lower support plate reserved bolts 5 are installed in the lower support reserved holes 51. In use, the lower end of the upper support plate reserved bolt 1 is fixedly connected to the upper end of the lower support plate reserved bolt 5. In specific implementation, the lower support reserved hole 51 can be a vertically opened threaded hole. The lower end of the lower support reserved hole 51 is connected to the top of the pier using an anchor sleeve assembly and a limit bolt assembly.

[0075] During transportation, in order to prevent the upper and lower plates of the support from colliding and sliding, a long screw is needed to directly connect the bolt holes of the upper and lower plates for fixation.

[0076] Specifically, the upper support plate sliding arc groove 7 and the lower support plate sliding arc groove 8 have the same radius of curvature.

[0077] The upper support plate sealing assembly is provided with a set of threaded holes along the X and Y axes respectively. The limiting bolt assembly contacts the lower support plate through the threaded holes to achieve unidirectional displacement constraint or bidirectional displacement constraint, so as to simulate a unidirectional movable support and a fixed support respectively.

[0078] In specific implementation, the upper support plate 2, the lower support plate 6, and the ball core of the shock-absorbing ball pendulum 10 are made of Q345 hot-rolled steel; the friction plate 9 can be made of polytetrafluoroethylene; and the anchor sleeve assembly and the limiting bolt assembly are made of M10 high-strength bolts.

[0079] Both the upper support plate sliding arc groove 7 and the lower support plate sliding arc groove 8 are concave spherical surfaces, and their radii of curvature are calculated and determined according to the principle that the natural vibration period and stiffness of the scaled model structure are equivalent to those of the original structure.

[0080] The lower support plate consists of a lower flat plate and a sliding spherical surface. The lower flat plate has the same structural form as the upper flat plate, with bolt holes at the four corners. The lower support plate is connected to the pier column via bolts pre-embedded in the lower pier column. The sliding spherical surface is a concave spherical surface with the same radius of curvature as the upper support plate.

[0081] The upper and lower surfaces of the shock-absorbing spherical pendulum are convex spherical surfaces, which fit into the sliding arc grooves of the upper and lower support plates. A polytetrafluoroethylene (PTFE) friction plate is placed between the sliding spherical surface and the shock-absorbing spherical pendulum to improve the friction energy dissipation capacity of the friction pendulum support during vibration. The friction coefficient of the support friction surface is consistent with that of the prototype bridge friction pendulum support.

[0082] During installation, the upper support plate is first connected to the main beam using pre-embedded bolts on the upper main beam, with the PTFE friction plate embedded in the friction surface of the upper support plate. Then, the shock-absorbing ball pendulum and the lower support plate with the embedded PTFE friction plate are placed in corresponding positions and connected to the upper support plate by spot welding with short steel bars to form a support assembly. Next, the main beam is hoisted to the pier position, the position of the lower support plate is finely adjusted so that it passes through the pre-embedded bolts on the pier, and the nuts are tightened to complete the installation of the lower support plate. Finally, the spot-welded short steel bars are removed to complete the support installation.

[0083] The above description of the disclosed embodiments is merely intended to assist those skilled in the art in implementing or using the methods and ideas of the invention. Furthermore, modifications to these embodiments will be readily achievable by those skilled in the art. The general principles defined herein can be applied to the design of scaled friction pendulum supports for shaking table experiments in various engineering projects without departing from the spirit or scope of the invention. Therefore, this specification should not be construed as limiting the invention.

Claims

1. A universal friction pendulum support for single and double displacement constraints in a seismic scaled-down test model, characterized in that: It includes an upper support plate (2) and a lower support plate (6), and a shock-absorbing ball pendulum (10) that is limited between the upper support plate (2) and the lower support plate (6). The upper support plate (2) has a sliding arc groove (7) at the bottom that contacts the upper surface of the shock-absorbing ball pendulum (10), and the lower support plate (6) has a sliding arc groove (8) at the top that contacts the lower surface of the shock-absorbing ball pendulum (10). Friction plates (9) that are in close contact with the shock-absorbing ball pendulum (10) are respectively provided in the sliding arc groove (7) of the upper support plate and the sliding arc groove (8) of the lower support plate; the upper support plate sliding arc groove (7) and the lower support plate sliding arc groove (8) have the same radius of curvature. An upper support plate wall panel (3) is provided on the upper support plate flat plate (2) to surround the outer periphery of the shock-absorbing ball pendulum (10); a plurality of limiting screws (4) extending to the outer wall of the sliding arc groove (8) of the lower support plate are symmetrically provided on the upper support plate wall panel (3). Friction pendulum support design method: Based on the concept of similarity in period and stiffness between shaking table experiments and actual bridge seismic isolation structures, the design parameters of the friction pendulum support curvature radius, support design displacement, and support yield displacement are determined: Step 1: Determine three controllable similarity constants based on the structural test site and shaking table performance parameters, namely the length similarity constant. Stress similarity constant acceleration similarity constant ; Step 2: Referencing the arrangement of seismic isolation bearings in the prototype structure, determine the equivalent number and location of seismic isolation bearings in the experimental structure. Step 3: Based on the equation analysis method and the dimensional analysis method, the similarity equation (1) that the physical quantity similarity constants of the structural shaking table test dynamics problem must satisfy is obtained: Equation (1) In equation (1), Represents the similarity coefficient of elastic modulus; Indicates the quality similarity coefficient; Indicates the acceleration similarity coefficient; The length similarity coefficient is represented by equation (1); equation (1) is further derived into equation (2), i.e. Equation (2) In equation (2), Indicates the stiffness similarity coefficient; Step 4: Determine the initial stiffness of the experimental scaled support parameters according to the principle of stiffness similarity: Equation (3) Stiffness after yielding: Equation (4) Equivalent stiffness: Equation (5) For the supports of the model structure, their stiffness satisfies the similarity relation: Equation (6) In the formula: Indicates the initial stiffness; Indicates the coefficient of friction of the support; W represents the vertical load. Indicates the yield displacement; R represents the stiffness after yielding; R represents the support curvature radius. Indicates equivalent stiffness; Indicates the design displacement of the support; and These represent the support stiffness of the scaled-down model and the original model, respectively; where the superscript m indicates the relevant parameters of the scaled-down model and p indicates the relevant parameters of the original model. From equations (3) and (6), we get: From equations (4) and (6), we get: From equations (5) and (6), we get: Step 5: Design and manufacture the scaled-down friction pendulum support based on the above calculation parameters.

2. The universal friction pendulum support for single and double displacement constraints in the seismic scaling test model according to claim 1, characterized in that: The friction plate (9) is made of polytetrafluoroethylene.

3. The universal friction pendulum support for single and double displacement constraints in the seismic scaling test model according to claim 1, characterized in that: The upper support plate enclosure (3) has a regular polygonal structure.

4. The universal friction pendulum support for single and double displacement constraints in the seismic scaling test model according to claim 1, characterized in that: The upper support plate (2) has upper support reserved holes (11) at its corners, and upper support plate reserved bolts (1) are installed in the upper support reserved holes (11). Or / and, the upper support reserved hole (11) is a vertically set threaded hole.

5. The universal friction pendulum support for single and double displacement constraints in the seismic scaling test model according to claim 4, characterized in that: Lower support reserved holes (51) are respectively opened at the corners of the lower support plate (6), and lower support plate reserved bolts (5) are installed in the lower support reserved holes (51). Or / and, the lower support reserved hole (51) is a vertically arranged threaded hole.

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