Anti-loosening double-comb-tooth type assembly type bridge expansion device

Abstract

An anti-loosening double-comb-tooth type assembly type bridge expansion device comprises a left pre-buried assembly (4) and a right pre-buried assembly (5) and is characterized in that a left expansion panel (7) is installed above the left pre-buried assembly (4), a right expansion panel (8) is installed above the right pre-buried assembly (5), and one or more rows of conical through holes (12) are formed in the left expansion panel (7) and the right expansion panel (8) respectively. The conical through hole (12) is internally anchored with the embedded assembly through a conical head check bolt (13), and the conical degree of the conical through hole (12) is the same as that of a conical head of the conical head check bolt (13). The bridge expansion device effectively solves the anchoring technical problem of an existing bridge expansion device, is reasonable in structure and convenient to install, can provide very strong downward anchoring pre-tightening force, and can effectively improve the anchoring efficiency of the bridge expansion device. And the anchoring strength of the telescopic device can be greatly enhanced.

Description

Technical Field

[0001] This invention relates to bridge expansion joints with anti-loosening anchoring structures, and more particularly to an anti-loosening double-comb type assembled bridge expansion joint, belonging to the field of road and bridge engineering technology. Background Technology

[0002] Bridge expansion joints are crucial connecting components installed on bridge expansion joints. Their reliability and stability directly affect the bridge's service life and the comfort and safety of traffic. The installation and fixing of bridge expansion joints require a large number of bolts as connections and fasteners. Due to the long-term stress of traffic, impacts, and various complex environmental factors, the bolts on bridge expansion joints face extremely harsh working conditions. Dynamic loads generated by vehicles, including vertical pressure, horizontal friction, and impact forces, subject traditional bolts to repeated tensile, compressive, and shear stresses. Over time, these bolts will loosen. Furthermore, thermal expansion and contraction due to temperature changes accelerate bolt loosening, while rainwater erosion can cause rust and corrosion on the bolt surface, weakening the friction between the bolt and the connecting parts, thus exacerbating bolt loosening and corrosion problems. Once the bolts loosen, the bolt heads protrude from the road surface, easily leading to accidents such as tire blowouts. Loose bolts can cause displacement, deformation, or even detachment of the comb plate or modular steel of the bridge's expansion joint. When vehicles pass over it, this can cause bumps, jumps, and other phenomena, leading to loss of vehicle control and traffic accidents.

[0003] Existing bolt and nut fastening methods suffer from high requirements for alignment accuracy between the upper and lower openings and limited installation space. For multiple mounting holes in a row on the comb plate, these holes need to be aligned with the holes on the nut sleeves of the embedded components below. Due to manufacturing precision limitations, it's difficult to guarantee precise alignment of each mounting hole, leading to problems where some bolts or nuts are difficult to screw in. Furthermore, the nut sleeves have a certain thickness; if the bolt or nut is misaligned or eccentric during installation, the nut sleeve cannot be fitted, making tightening impossible.

[0004] While existing measures address bolt loosening issues, such as using high-strength bolts and increasing bolt preload, these methods still have limitations in practical applications. Although high-strength bolts can improve fatigue resistance and load-bearing capacity to some extent, loosening is still difficult to completely avoid under long-term vehicle loads and harsh environments, and they may even fail prematurely due to excessive tensile forces during use. More importantly, the annular contact area between the bolt head and the fastener is relatively small, and even adding anti-loosening and anti-slip grooves to the annular contact surface does not fundamentally solve the problem of easy loosening. Therefore, there is an urgent need to develop a new type of anti-loosening structure for bridge expansion joint bolts to improve the reliability and stability of bridge expansion joints, ensuring safe bridge operation and the comfort and safety of traffic. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing bridge expansion joints, which are prone to loosening under long-term vehicle loads and harsh environments. Existing measures to solve the bolt loosening problem have limitations, and the problem is still difficult to completely avoid. This invention provides a double-comb type prefabricated bridge expansion joint with a reasonable structure, convenient construction and installation, which effectively solves the technical problem of easy loosening of fastening bolts in existing bridge expansion joints. It can adapt well to the dynamic load changes generated by vehicle travel and also has good fatigue resistance and tensile strength.

[0006] To achieve the above objectives, the technical solution of the present invention is: a double-comb type prefabricated bridge expansion joint with anti-loosening mechanism, comprising a left pre-embedded component and a right pre-embedded component. A left expansion panel is installed above the left pre-embedded component, and a right expansion panel is installed above the right pre-embedded component. The left and right expansion panels are respectively provided with comb teeth or wavy comb teeth on the side where they connect. The left and right expansion panels interlock with each other through the comb tooth structure, or the left and right expansion panels are connected through wavy edges. One or more rows of conical through holes are respectively opened on the left and right expansion panels. Conical anti-loosening bolts are anchored to the pre-embedded components in the conical through holes. The taper of the conical through holes is the same as the taper of the conical anti-loosening bolt.

[0007] Furthermore, the left and right telescopic panels are respectively provided with comb teeth or wavy comb teeth on the side where they are connected. The left and right telescopic panels interlock with each other through the comb tooth structure, or the left and right telescopic panels are connected through the wavy edge. The left and right telescopic panels are respectively provided with multiple telescopic panel notches or multiple large through openings on the side away from the beam end gap.

[0008] Furthermore, the left telescopic panel is the same as or symmetrical to the right telescopic panel, and two of the supporting holes in a row of conical through holes on the left and right telescopic panels are countersunk holes, or four supporting holes on the left and right telescopic panels are countersunk holes.

[0009] Furthermore, the conical head anti-loosening bolt includes a conical head, a conical clamping surface, an internal hexagon countersunk hole, and a screw section. One end of the screw section is integrally provided with a conical head, the outer surface of the conical head is provided with a conical clamping surface, and an internal hexagon countersunk hole is opened in the circular center of the conical head. The diameter of the end of the conical head near the screw is smaller than the diameter of the upper end of the conical head.

[0010] Furthermore, one or more rows of vertically arranged nut sleeves are fixedly installed on the left and right pre-embedded components. The positions of the nut sleeves correspond to the positions of the conical through holes and countersunk holes opened on the telescopic panel. The specifications of the nut sleeves are matched with the conical anti-loosening bolts and screws.

[0011] Furthermore, an elevation elastic adjustment structure is installed between the telescopic panel and the corresponding pre-embedded component at the bottom. A horizontally arranged metal part is welded to the original bridge abutment pre-embedded rib or pre-embedded component at the bottom or outer side of the telescopic panel. The outer side, bottom surface or inner side of the telescopic panel notch is connected and fixed to the metal part by welding connectors, or is connected and fixed to the rebar on the bridge abutment by welding.

[0012] Furthermore, horizontally arranged straight steel bars are welded to the original bridge abutment embedded bars or embedded components at the bottom or the outer side of the bottom of the telescopic panel. The outer side, bottom surface or inner side of the telescopic panel notch are welded and fixed to the straight steel bars by multiple spaced U-shaped steel bars, 7-shaped steel bars or Z-shaped steel bars.

[0013] Furthermore, the elevation elastic adjustment structure includes a high-strength screw, an adjustable thin nut, a preload spring, and a fastening nut. The bottom end of the high-strength screw is vertically installed inside the nut sleeve, the upper end of the high-strength screw passes through a countersunk hole, the lower part of the high-strength screw is equipped with an adjustable thin nut, the preload spring is placed on the adjustable thin nut, the bottom surface of the telescopic panel rests on the upper end of the preload spring, and the upper end of the high-strength screw, located inside the countersunk hole, is equipped with a fastening nut.

[0014] Furthermore, the notch or through opening of the telescopic panel can partially cover the concealed area of ​​the concrete pouring below the telescopic panel. The total area of ​​the notch or multiple through openings of the unit telescopic panel is not greater than 1 / 2 of the area of ​​the unit telescopic tooth plate excluding the comb teeth, and the total area of ​​the notch or multiple through openings of the unit telescopic panel is not less than 1 / 5 of the area of ​​the unit telescopic tooth plate excluding the comb teeth.

[0015] Furthermore, the conical surface and / or the conical pressing surface of the conical through hole are provided with anti-slip textures, anti-slip floating points, or anti-slip concave points.

[0016] Furthermore, the taper of the conical through hole and the taper of the conical pressing surface are greater than 2 / 3.

[0017] The beneficial effects of this invention are:

[0018] 1. The present invention adopts a structure in which a tapered through hole is matched with a screw with a frustum screw head. The screw is matched with a threaded sleeve or nut, which greatly increases the contact area or support area between the frustum screw and the comb plate, and significantly increases the friction torque of the contact area or support area.

[0019] 2. This invention adopts an elastic height adjustment structure and a conical head bolt anti-loosening structure, which can accurately adjust the height and level of the telescopic panel. After the conical through hole and the conical pressing surface of the conical head anti-loosening bolt are pressed together, compared with the traditional nut and screw fixing method and the ordinary bolt tightening method, the contact area is greatly increased and the static friction area is also greatly increased, which can provide a very strong downward anchoring pre-tightening force and achieve a very good anti-loosening effect.

[0020] 3. Under the action of the tapered hole with a larger upper part and a smaller lower part, the tapered bolt of the present invention provides a greater tightening force and a greater downward pressure on the telescopic panel. It can adapt well to the dynamic load changes generated during vehicle operation and will not loosen even under complex external forces such as vertical pressure, horizontal friction and impact. It also has good fatigue resistance and tensile strength.

[0021] 4. This invention adopts a dual anchoring method that combines bolt anchoring and welding anchoring. Welding anchoring can minimize the shear fatigue of bolts caused by impact loads, while the sufficient prestress of bolt anchoring can in turn alleviate the impact fatigue at the stress concentration points of welding anchoring. The two anchoring methods complement each other, cleverly solving the process defects of single anchoring and greatly enhancing the anchoring strength of the expansion joint.

[0022] 5. This invention effectively solves the anchoring technical problems existing in the current bridge expansion joints. It has a reasonable structure, is easy to install, and can provide a very strong downward anchoring pre-tightening force, which can greatly enhance the anchoring strength of the expansion joint and has broad application prospects. Attached Figure Description

[0023] Figure 1 This is an installation process diagram of the first embodiment of the present invention.

[0024] Figure 2 This is a top view of the first embodiment of the present invention.

[0025] Figure 3 yes Figure 2 A magnified view of a portion of the image.

[0026] Figure 4 This is a schematic diagram of the structure of the telescopic panel according to the first embodiment of the present invention.

[0027] Figure 5 yes Figure 1 Schematic diagram of the cross-sectional structure of AA.

[0028] Figure 6 yes Figure 2 Schematic diagram of the cross-sectional structure of BB.

[0029] Figure 7 This is a cross-sectional view of the portion of the invention in which a high-strength screw is installed, according to the first embodiment of the invention.

[0030] Figure 8 This is a top view of the second embodiment of the present invention.

[0031] Figure 9 This is a schematic diagram of the telescopic panel according to the second embodiment of the present invention.

[0032] Figure 10 This is a cross-sectional structural diagram of the second embodiment of the present invention.

[0033] Figure 11 yes Figure 6 Schematic diagram of the cross-sectional structure of BB.

[0034] Figure 12 This is a cross-sectional view of the conical through hole of the present invention.

[0035] Figure 13 This is a schematic diagram of the structure of the conical head anti-loosening bolt of the present invention.

[0036] Figure 14 This is an installation state diagram of the first embodiment of the present invention.

[0037] In the diagram: 1. Concrete beam; 2. Beam end gap; 3. Original abutment embedded reinforcement; 4. Left embedded component; 5. Right embedded component; 6. Nut sleeve; 7. Left telescopic panel; 8. Right telescopic panel; 9. Telescopic panel notch; 10. Comb teeth; 11. Wavy edge; 12. Conical through hole; 13. Conical head anti-loosening bolt; 13. Conical head; 13-1. Conical clamping surface; 13-2. Hexagonal countersunk hole; 13-3. Screw section; 13-4. Countersunk hole; 14. Screw; 15. Preload spring; 16. Fastening nut; 17. Straight reinforcing bar; 18. Welded connector; 19. Armored wear-resistant and anti-slip layer; 20. Stainless steel drainage structure; 21. High-strength concrete; 22. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] See Figures 1 to 14 The present invention discloses a double-comb type prefabricated bridge expansion joint with anti-loosening mechanism, comprising a left pre-embedded component 4 and a right pre-embedded component 5. The invention is characterized in that: a left expansion panel 7 is installed above the left pre-embedded component 4, and a right expansion panel 8 is installed above the right pre-embedded component 5. Comb teeth 10 or wavy comb teeth 11 are respectively provided on the side where the left expansion panel 7 and the right expansion panel 8 connect. The left expansion panel 7 and the right expansion panel 8 interlock through the comb teeth structure, or they are connected by wavy edges. One or more rows of conical through holes 12 are respectively opened on the left expansion panel 7 and the right expansion panel 8. Conical anti-loosening bolts 13 are anchored to the pre-embedded components within the conical through holes 12. The taper of the conical through holes 12 is the same as the taper of the conical anti-loosening bolts 13.

[0040] The left telescopic panel 7 and the right telescopic panel 8 are respectively provided with comb teeth 10 or wavy comb teeth 11 on the side where they are connected. The left telescopic panel 7 and the right telescopic panel 8 are interlocked by the comb teeth structure, or the left telescopic panel 7 and the right telescopic panel 8 are connected by the wavy edge. The left telescopic panel 7 and the right telescopic panel 8 are respectively provided with multiple telescopic panel notches 9 or multiple large through openings on the side away from the beam end gap 2.

[0041] The left telescopic panel 7 and the right telescopic panel 8 are the same or symmetrical. Two of the row of conical through holes 12 on the left telescopic panel 7 and the right telescopic panel 8 that can play a supporting role are set as countersunk holes 14, or four holes on the left telescopic panel 7 and the right telescopic panel 8 that can play a supporting role are set as countersunk holes 14.

[0042] The conical head anti-loosening bolt 13 includes a conical head 13-1, a conical clamping surface 13-2, an internal hexagon countersunk hole 13-3, and a screw section 13-4. One end of the screw section 13-4 is integrally provided with a conical head 13-1. The outer surface of the conical head 13-1 is provided with a conical clamping surface 13-2. An internal hexagon countersunk hole 13-3 is opened at the circular center of the conical head 13-1. The diameter of the end of the conical head 13-1 near the screw 7 is smaller than the diameter of the upper end of the conical head 13-1.

[0043] One or more rows of vertically arranged nut sleeves 6 are fixedly installed on the left pre-embedded component 4 and the right pre-embedded component 5. The position of the nut sleeves 6 corresponds to the position of the conical through hole 12 and the countersunk hole 14 opened on the telescopic panel. The specifications of the nut sleeves 6 are matched with the conical anti-loosening bolt 13 and the screw 15.

[0044] An elevation elastic adjustment structure is installed between the telescopic panel and the corresponding pre-embedded component at the bottom. A horizontally set metal part is welded to the original bridge abutment pre-embedded reinforcement 3 or pre-embedded component at the bottom or outside of the telescopic panel. The outer side, bottom surface or inner side of the telescopic panel notch is connected and fixed to the metal part by welding connectors, or is connected and fixed to the reinforcement on the bridge abutment by welding.

[0045] The bottom or bottom outer side of the telescopic panel is provided with horizontally arranged straight steel bars 18 welded on the original bridge abutment embedded bars 3 or embedded components. The outer side, bottom surface or inner side of the telescopic panel notch is fixed to the straight steel bars 18 by multiple spaced U-shaped steel bars, 7-shaped steel bars or Z-shaped steel bars.

[0046] The elevation elastic adjustment structure includes a high-strength screw 15, an adjustable thin nut, a preload spring 16, and a fastening nut 17. The bottom end of the high-strength screw 17 is vertically installed inside the nut sleeve 6. The upper end of the high-strength screw 17 passes through the countersunk hole 14. The adjustable thin nut is installed on the lower part of the high-strength screw 17. The preload spring 16 is placed on the adjustable thin nut. The bottom surface of the telescopic panel rests on the upper end of the preload spring 16. The fastening nut 17 is installed on the upper end of the high-strength screw 17 and inside the countersunk hole 14.

[0047] The telescopic panel notch 9 or through opening can partially cover the concealed area of ​​the concrete pouring below the telescopic panel. The total area of ​​the unit telescopic panel notch 9 or multiple through openings is not greater than 1 / 2 of the area of ​​the unit telescopic tooth plate excluding the comb teeth, and the total area of ​​the unit telescopic panel notch 9 or multiple through openings is not less than 1 / 5 of the area of ​​the unit telescopic tooth plate excluding the comb teeth.

[0048] The conical surface of the conical through-hole 12 and / or the surface of the conical pressing surface 13-2 are provided with anti-slip textures, anti-slip floating points, or anti-slip concave points. The taper of the conical through-hole 12 and the taper of the conical pressing surface 13-2 are greater than 2 / 3.

[0049] See Figures 1 to 11 The anti-loosening fastening structure of this application adopts a structure in which a conical through hole is matched with a conical anti-loosening bolt, and the screw is matched with a threaded sleeve or nut. This anti-loosening fastening structure is suitable not only for fastening expansion joints of comb-plate bridges, but also for fastening modular bridge expansion joints, achieving excellent anti-loosening fastening results. Through extensive field investigation and research, the structure of the expansion panel has been creatively improved, and a dual anchoring method of conical anti-loosening bolt anchoring plus welded anchoring of the expansion panel has been cleverly adopted. The elevation elastic adjustment structure facilitates the construction of the post-grouting method. This application effectively solves a series of previously unresolved technical problems and achieves unique technical effects exceeding expectations. The specific structure and principle are as follows:

[0050] The site conditions before installation of this invention are the same as those before installation of existing bridge expansion joints, both involving installation at the bridge abutment expansion joint. The installation groove of bridge abutment 1 contains pre-embedded reinforcing bars 3 from the original bridge abutment. Pre-embedded reinforcing bars are not required in the steel box girder groove. The pre-embedded reinforcing bars 3 from the original bridge abutment can be welded and fixed to the pre-embedded components of the expansion joint to be installed, allowing the pre-embedded components and other expansion joint parts to be fixed to bridge abutment 1 as a single structure. A left pre-embedded component 4 is installed in the installation groove of bridge abutment 1 on one side of the beam end gap 2. The left pre-embedded component 4 is connected and fixed to the pre-embedded reinforcing bars 3 from the original bridge abutment or the top surface of the steel box girder below by welding or other methods. A right pre-embedded component 5 is installed in the installation groove of bridge abutment 1 on the other side of the beam end gap 2. The right pre-embedded component 5 is connected and fixed to the pre-embedded reinforcing bars 3 from the original bridge abutment or the top surface of the steel box girder below on the corresponding side by welding or other methods.

[0051] The left and right embedded components 4 and 5 are frame-type steel structures, serving as the installation foundation for the telescopic panel. They are pre-fabricated in the factory with high precision, ensuring high-precision assembly of the telescopic panel and enhancing the overall rigidity and load-bearing capacity of the telescopic device. One or more rows of vertically arranged nut sleeves 6 are fixedly installed on the left and right embedded components 4 and 5. Generally, two rows of equally spaced nut sleeves 6 are used. For telescopic panels with small telescopic ranges and limited installation areas, a single row of equally spaced nut sleeves 6 can also be used. The positions of the nut sleeves 6 correspond to the positions of the conical through holes 12 and countersunk holes 14 on the telescopic panel. The specifications of the nut sleeves 6 are matched with the conical anti-loosening bolts 13 and the screws 15.

[0052] A left telescopic panel 7 is installed above the left pre-embedded component 4, and a right telescopic panel 8 is installed above the right pre-embedded component 5. Unlike traditional telescopic panels, which are distributed on both sides and differ in size and orientation (one panel being larger, 60-110 cm wide, and the other smaller, 30-50 cm wide), this invention uses identical left and right telescopic panels 7 and 8, which are interchangeable or symmetrical. This eliminates the size and orientation differences, improving installation convenience and efficiency. The telescopic panel is made of high-strength steel plate with a thickness of 2.5 cm to 6 cm. The left telescopic panel 7 and the right telescopic panel 8 are respectively provided with comb teeth 10 or wavy edges 11 on the side where they are connected. The left telescopic panel 7 and the right telescopic panel 8 are interlocked by the comb teeth structure, or the left telescopic panel 7 and the right telescopic panel 8 are connected by the wavy edges. A certain telescopic gap is reserved between the left telescopic panel 7 and the right telescopic panel 8 to ensure the telescopic movement space of the telescopic panel.

[0053] More importantly, to address the issues of concrete density and ease of construction in the concealed area at the bottom of the telescopic panel, this invention provides multiple telescopic panel notches 9 or multiple through openings on the side of the telescopic panel away from the beam end gap 2. These notches 9 or through openings can be evenly or unequally spaced. The notches 9 or through openings can be squares or rectangles with rounded corners, or curved notches without sharp corners. The total area of ​​a single telescopic panel notch or through opening is no greater than half the area of ​​the single telescopic toothed plate excluding the comb teeth, and no less than one-fifth the area of ​​the single telescopic toothed plate excluding the comb teeth. The remaining concealed area is optimized and minimized to facilitate vibration of the concrete in a certain area below the telescopic panel through the notches 9 or through openings, while also allowing excess concrete to overflow from the notches 9 or through openings. During the pouring process, the visibility of the pouring area under the expansion panel is greatly expanded, which also facilitates local vibration of various parts. This ensures that the concrete can be evenly and densely distributed on the bottom of the expansion panel and all nearby areas that need to be poured. This cleverly solves the technical problem that the concrete density at the bottom of the expansion panel is poor due to its large area.

[0054] To achieve reliable anchoring of the telescopic panels, this invention employs an anchoring structure consisting of conical through holes and conical anti-loosening bolts. Specifically, one or more rows of conical through holes 12 are respectively opened on the left telescopic panel 7 and the right telescopic panel 8. The positions of the conical through holes 12 correspond one-to-one with the nut sleeves on the pre-embedded components. The inner wall of the conical through hole 12 is set as a conical surface, and the large-diameter end of the conical through hole 12 is located on the upper surface of the telescopic panel. The diameter of the bottom end of the conical through hole 12 is smaller than the diameter of the top end of the conical through hole 12. A conical anti-loosening bolt 13 is installed inside the conical through hole 12. The conical anti-loosening bolt 13 includes a conical head 13-1, a conical clamping surface 13-2, a hexagonal countersunk hole 13-3, and a screw section 13-4. One end of the screw section 13-4 is integrally provided with the conical head 13-1. The outer surface of the conical head 13-1 is provided with the conical clamping surface 13-2. The taper of the conical clamping surface 13-2 is the same as the taper of the conical through hole 12. A hexagonal countersunk hole 13-3 is opened at the circular center of the conical head 13-1. The diameter of the end of the conical head 13-1 near the screw 7 is smaller than the diameter of the upper end of the conical head 13-1. Anti-slip textures, anti-slip floating points, or anti-slip concave points can also be provided on the inner wall of the conical through hole 12 and / or the surface of the conical clamping surface 13-2 to further improve the loosening performance. Extensive experiments have shown that the anchoring structure consisting of a conical through-hole and a conical head anti-loosening bolt significantly increases the friction area and the friction torque on the supporting surface, thus ensuring sufficient preload.

[0055] Compared with the traditional fixing method of nuts and bolts and the fastening method of ordinary bolts, the area of ​​the fastening and pressing surface of the nut or ordinary bolt after the traditional fastening method is very small, and the static friction area is also very small. After long-term repeated crushing and impact by vehicles, the telescopic panel is easy to loosen or even fall off. However, after the conical through hole and the conical pressing surface of the conical head anti-loosening bolt of the present invention are pressed together, the contact area is greatly increased due to the close contact between the conical surfaces, and the static friction area is also greatly increased. Furthermore, during the fastening process by the conical head anti-loosening bolt 13, thanks to the unique structure of the conical surface, the telescopic panel will become tighter and tighter, providing a very strong downward anchoring preload. Multiple tests have shown that even if the conical head anti-loosening bolt 13 is disassembled under human intervention or becomes loose during the natural use of the telescopic device, the strong static friction between the conical pressing surface of the conical head anti-loosening bolt 13 and the inner wall of the conical through hole 12 must be overcome first. After the conical head anti-loosening bolt 13 is pre-tightened by power tools or a pneumatic wrench, it is almost impossible to disassemble it again, and it will not loosen during use.

[0056] The theoretical analysis of the anti-loosening performance of this invention is as follows:

[0057] For 8.8 grade M20 nuts that rely solely on friction for loosening prevention, their loosening prevention capability is directly related to the friction area of ​​the nut or bolt head bearing surface. The core relationship lies in the calculation of the frictional torque resisting loosening. The key formulas and logical relationships are as follows:

[0058] Core relationship: Anti-loosening friction torque vs. friction area

[0059] The nut's ability to resist loosening mainly comes from two frictional torques:

[0060] 1. The frictional torque between threaded pairs is related to the thread contact area and positively correlated with the biting distance.

[0061] 2. The frictional torque between the nut support surface and the connecting parts is directly related to the frictional area.

[0062] The total anti-loosening friction torque consists of these two parts:

[0063] Among them, the friction torque of the supporting surface is the key point, and its relationship with the friction area is the most direct.

[0064] The frictional torque of a threaded pair is mainly related to the thread size, the coefficient of friction, and the preload. Increasing the friction area requires increasing the equivalent friction diameter, which linearly increases the frictional torque and improves the anti-loosening capability.

[0065] Specific parameters and calculations for grade 8.8 M20 nuts:

[0066] 1. Bolt parameters (M20, grade 8.8):

[0067] Nominal diameter d = 20 mm = 0.02 m

[0068] Pitch P ≈ 2.5 mm (standard coarse thread)

[0069] The thread pitch diameter d2 ≈ 18.376 mm

[0070] The stress cross-sectional area A_s ≈ 245 mm²

[0071] Yield strength: Grade 8.8 → Tensile strength 800 MPa, yield strength 640 MPa.

[0072] Recommended preload Fp: typically 70% - 90% of yield strength. A conservative design would be 70%.

[0073] Fp = 0.7 × 640 × 10 6 ×245×10- 6 =0.7×640×245=107520 N

[0074] In this case, the multiplication of 10 to the power of 6 and 10 to the power of -6 cancels out, so in the end only the product of the coefficient and the value needs to be calculated.

[0075] 2. Friction coefficient μb:

[0076] Typical ranges: Steel to steel (dry) 0.10 - 0.18; Steel to steel (oiled) 0.08 - 0.12; Steel to cast iron 0.12 - 0.15. Calculation example uses μb = 0.14 (medium-clean steel surface).

[0077] 3. Friction area and equivalent diameter dw:

[0078] Standard nut (M20): Width across flats S = 30 mm, outer diameter of bearing surface Do ≈ 34.6 mm, inner diameter Di = 22 mm (through hole diameter). Friction area ≈ 538 mm². Using a flange nut, for example, with an outer diameter Do = 40 mm: friction area ≈ 847 mm². Using a tapered screw with an outer diameter of bearing surface Do ≈ 56 mm: friction area ≈ 2082 mm².

[0079] 4. Calculate the frictional torque of the supporting surface.

[0080] Standard nut: ≈213.2 N·m

[0081] Flange nut: ≈233.6 N·m

[0082] Tapered screw: ≈587.1 N·m

[0083] Results comparison: Friction area increased (538 mm² → 847 mm² → 2082 mm²).

[0084] The equivalent friction diameter increases (28.3 mm → 31.0 mm → 56.0 mm).

[0085] The frictional torque on the supporting surface increases (213.2 N·m → 233.6 N·m → 587.1 N·m).

[0086] in conclusion:

[0087] 1. Clarify the relationship: The friction area of ​​the nut support surface increases linearly through the equivalent friction diameter to increase the anti-loosening friction torque.

[0088] 2. Effect: Increasing the friction area (e.g., using flange nuts) has a limited contribution to improving the anti-loosening ability (approximately 9% in this example).

[0089] The conical head anti-loosening bolt of the present invention makes a significant contribution to improving the anti-loosening capability, approximately 175% in this example.

[0090] 3. A more effective method:

[0091] Ensure sufficient preload: This is fundamental to preventing loosening. Control the coefficient of friction: Choose stable and appropriate surface treatment / lubrication. Increase the equivalent friction diameter: Using the tapered screw release mechanism of this invention can significantly increase the frictional torque on the support surface, with a significantly better effect than traditional fasteners such as flange nuts.

[0092] Key points of M20 level 4.8.8:

[0093] It can achieve high preload (approximately 107 kN).

[0094] In situations like those described in this invention, which involve repeated crushing impacts and high vibrations, the relaxation and destructive structure of this invention is essential.

[0095] Multiple fatigue tests have shown that the anti-loosening capability is directly related to the friction area of ​​the nut or bolt head's supporting surface. Firstly, the nut or bolt head's resistance to loosening primarily comes from two frictional torques: the frictional torque between the threaded pairs, which is related to the thread contact area and positively correlated with the undercut distance; and secondly, the frictional torque between the nut or bolt head's supporting surface and the connecting part, which is directly related to the frictional area. The total anti-loosening frictional torque consists of these two parts, with the supporting surface frictional torque being the key, as its relationship with the frictional area is the most direct. The threaded pair frictional torque is mainly related to the thread size, friction coefficient, and preload. Increasing the frictional area requires increasing the equivalent friction diameter, thus linearly increasing the frictional torque and greatly improving the anti-loosening capability. The anti-loosening and pull-out resistance of the conical head bolt anti-loosening structure used in this invention is more than 5 times higher than that of traditional bolts or nuts.

[0096] Traditional bridge expansion joints' expansion panels are subjected to significant horizontal shear forces during use due to repeated impacts from vehicles. Traditional vertically installed bolts are prone to bending or even breakage under these shear forces. To address the issue of weak shear resistance in expansion panels, this invention incorporates horizontally welded metal components to the original bridge abutment embedded reinforcement 3 or other pre-embedded components at the bottom or outer bottom of the expansion panel. One end of a welded connector 19 is welded to the outer side, bottom surface, or notch 9 or multiple through-opening sides of the expansion panel. The other end of the welded connector 19 is also welded to the original bridge abutment embedded reinforcement 3 or the horizontally welded metal component. If the original bridge abutment embedded reinforcement 3 or the horizontally welded metal component is missing, the other end of the welded connector 19 can be anchored to the bridge abutment using epoxy resin anchoring. The welded connector 19 consists of multiple spaced U-shaped, L-shaped, or Z-shaped steel bars. After welding and fixing, the connection strength of the telescopic panel in the horizontal direction can be significantly improved. The long strip metal parts and welded connectors 19 can form an integral structure with the pre-embedded components after the concrete is poured, and the telescopic panel has better resistance to shear force and impact.

[0097] This invention employs a dual anchoring method combining bolt anchoring and welded anchoring. Welded anchoring can minimize the shear fatigue of bolts caused by impact loads, while the sufficient prestress of bolt anchoring can, in turn, effectively alleviate the impact fatigue at stress concentration points of welded anchoring. The two anchoring methods complement each other, cleverly solving the technological defects of single anchoring and greatly enhancing the anchoring strength of the expansion joint.

[0098] In order to accurately adjust the height and level of the telescopic panel during installation, the present invention adopts an elastic height adjustment structure for temporary support and fixation before the telescopic panel is finally fixed by the conical anti-loosening bolts 13. Two of the conical through holes 12 on the left telescopic panel 7 and the right telescopic panel 8 that can play a supporting role are set as countersunk holes 14 or stepped holes, or four holes on the left telescopic panel 7 and the right telescopic panel 8 that can play a supporting role are set as countersunk holes 14 or stepped holes. The elevation elastic adjustment structure includes a screw 15, an adjustable preload spring 16, and a fastening nut 17. The bottom end of the screw 15 is vertically installed inside the nut sleeve 6, and the upper end of the screw 15 passes through the countersunk hole 14. The adjustable preload spring 16 is fitted on the screw 15, and the bottom surface of the telescopic panel rests on the upper end of the adjustable preload spring 16. The adjustable preload spring 16 can support the telescopic panel and provide the vertical adjustment space required for precise adjustment. The fastening nut 17 is installed at the upper end of the screw 15 and inside the countersunk hole 14. By rotating each fastening nut 17 up and down, the telescopic panel can be precisely adjusted, ensuring the flatness of the connection between the telescopic panel and the bridge road surface and improving driving comfort.

[0099] High-strength concrete 22 is poured between the bottom surface of the telescopic panel and the abutment 1. High-strength concrete 22 is also poured at the telescopic panel notch 9 or multiple through-holes and transition zones. The upper surface of the high-strength concrete 22 poured at the telescopic panel notch 9 or multiple through-holes and transition zones is 5 mm-10 mm lower than the upper surface of the telescopic panel, forming a wear-resistant and anti-slip reinforcement area. After the concrete has solidified and cured, an interface agent is applied to the surface of the wear-resistant and anti-slip reinforcement area to repair the physical shrinkage cracks that naturally occur after the concrete solidifies. Then, an armored wear-resistant and anti-slip layer 20 is filled into the wear-resistant and anti-slip reinforcement area. The upper surface of the armored wear-resistant and anti-slip layer 20 is flush with the upper surface of the telescopic panel. The armored wear-resistant and anti-slip layer 20 uses a wear-resistant and anti-slip material that can solidify or harden, such as a mixture of epoxy resin and wear-resistant particles. The armor wear-resistant and anti-slip layer 20 has good adhesion and wear-resistant anti-slip properties, which can improve the grip of vehicle tires when passing over the telescopic panel, prevent the vehicle from slipping, and at the same time solve the problem of fatigue damage of traditional transition zone concrete.

[0100] In addition, a stainless steel drainage structure 21 is installed between the bottom of the telescopic panel and the pre-embedded components. Located directly below the comb teeth 10 or the wavy edge 11, the stainless steel drainage structure 21 collects and catches rainwater, discharging it downwards through a drainage funnel. The drainage channel of the stainless steel drainage structure 21 has a V-shaped or U-shaped cross-section. Both the water trough portion and the joint section of the drainage section of the stainless steel drainage structure 21 are made of stainless steel, making them rust-proof and corrosion-resistant, and resulting in a longer service life compared to traditional rubber drainage channel structures.

[0101] The above description is a further detailed explanation of the present invention in conjunction with specific embodiments. It should not be considered that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, any simple modifications and substitutions made without departing from the concept of the present invention should be considered to fall within the protection scope of the present invention.

Claims

1. A double-comb type prefabricated bridge expansion joint with anti-loosening mechanism, comprising a left pre-embedded component (4) and a right pre-embedded component (5), characterized in that: A left telescopic panel (7) is installed above the left pre-embedded component (4), and a right telescopic panel (8) is installed above the right pre-embedded component (5). The left telescopic panel (7) and the right telescopic panel (8) are respectively provided with comb teeth (10) or wavy comb teeth (11) on the side where they are connected. The left telescopic panel (7) and the right telescopic panel (8) are interlocked by the comb teeth structure, or the left telescopic panel (7) and the right telescopic panel (8) are connected by wavy edges. One or more rows of conical through holes (12) are opened on the left telescopic panel (7) and the right telescopic panel (8). The conical through holes (12) are anchored to the pre-embedded component by conical head anti-loosening bolts (13). The taper of the conical through holes (12) is the same as the taper of the conical head anti-loosening bolts (13).

2. The anti-loosening double-comb type assembled bridge expansion joint according to claim 1, characterized in that: The left telescopic panel (7) and the right telescopic panel (8) are respectively provided with comb teeth (10) or wavy comb teeth (11) on the side where they are connected. The left telescopic panel (7) and the right telescopic panel (8) are interlocked by the comb teeth structure, or the left telescopic panel (7) and the right telescopic panel (8) are connected by wavy edges. The left telescopic panel (7) and the right telescopic panel (8) are respectively provided with multiple telescopic panel notches (9) or multiple large through openings on the side away from the beam end gap (2).

3. The anti-loosening double-comb type assembled bridge expansion joint according to claim 1, characterized in that: The left telescopic panel (7) is the same as or symmetrical to the right telescopic panel (8). Two of the conical through holes (12) on the left telescopic panel (7) and the right telescopic panel (8) that can play a supporting role are set as countersunk holes (14), or four holes on the left telescopic panel (7) and the right telescopic panel (8) that can play a supporting role are set as countersunk holes (14).

4. The anti-loosening double-comb type assembled bridge expansion joint according to claim 1, characterized in that: The conical head anti-loosening bolt (13) includes a conical head (13-1), a conical clamping surface (13-2), an internal hexagon countersunk hole (13-3), and a screw section (13-4). One end of the screw section (13-4) is integrally provided with a conical head (13-1). The outer surface of the conical head (13-1) is provided with a conical clamping surface (13-2). An internal hexagon countersunk hole (13-3) is opened in the circular center of the conical head (13-1). The diameter of the end of the conical head (13-1) near the screw (7) is smaller than the diameter of the upper end of the conical head (13-1).

5. The anti-loosening double-comb type assembled bridge expansion joint according to claim 1, characterized in that: The left pre-embedded component (4) and the right pre-embedded component (5) are fixedly provided with one or more rows of vertically arranged nut sleeves (6). The position of the nut sleeves (6) corresponds to the position of the conical through hole (12) and countersunk hole (14) opened on the telescopic panel. The specifications of the nut sleeves (6) are matched with the conical anti-loosening bolt (13) and the screw (15).

6. The anti-loosening double-comb type assembled bridge expansion joint according to claim 1, characterized in that: An elevation elastic adjustment structure is installed between the telescopic panel and the corresponding pre-embedded component at the bottom. A horizontally arranged metal part is welded on the original bridge abutment pre-embedded bar (3) or pre-embedded component at the bottom or outside of the telescopic panel. The outer side, bottom surface or inner side of the telescopic panel notch is connected and fixed to the metal part by welding connectors, or is connected and fixed to the rebar on the bridge abutment by welding.

7. The anti-loosening double-comb type assembled bridge expansion joint according to claim 1, characterized in that: The bottom or bottom outer side of the telescopic panel is provided with horizontally arranged straight steel bars (18) welded on the original bridge abutment embedded bars (3) or embedded components. The outer side, bottom surface or inner side of the telescopic panel notch is fixed to the straight steel bars (18) by multiple spaced U-shaped steel bars, 7-shaped steel bars or Z-shaped steel bars.

8. The anti-loosening double-comb type assembled bridge expansion joint according to claim 6, characterized in that: The elevation elastic adjustment structure includes a high-strength screw (15), an adjustable thin nut, a preload spring (16), and a fastening nut (17). The bottom end of the high-strength screw (17) is vertically installed inside the nut sleeve (6). The upper end of the high-strength screw (17) passes through the countersunk hole (14). An adjustable thin nut is installed on the lower part of the high-strength screw (17). The preload spring (16) is placed on the adjustable thin nut. The bottom surface of the telescopic panel rests on the upper end of the preload spring (16). The fastening nut (17) is installed on the upper end of the high-strength screw (17) and located inside the countersunk hole (14).

9. The anti-loosening double-comb type assembled bridge expansion joint according to claim 2, characterized in that: The telescopic panel notch (9) or through opening can partially cover the concealed area of ​​the concrete pouring below the telescopic panel. The total area of ​​the unit telescopic panel notch (9) or multiple through openings is not greater than 1 / 2 of the area of ​​the unit telescopic tooth plate excluding the comb teeth, and the total area of ​​the unit telescopic panel notch (9) or multiple through openings is not less than 1 / 5 of the area of ​​the unit telescopic tooth plate excluding the comb teeth.

10. The anti-loosening double-comb type assembled bridge expansion joint according to claim 1, characterized in that: The conical surface of the conical through hole (12) and / or the conical pressing surface (13-2) are provided with anti-slip textures, anti-slip floating points or anti-slip concave points, and the taper of the conical through hole (12) and the taper of the conical pressing surface (13-2) are greater than 2 / 3.

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