Based on the anti-fracture bolt connection pair structure for long-span steel bridges

Abstract

This utility model discloses a fracture-resistant bolt connection pair structure for long-span steel bridges, including a bolt body, an anti-loosening nut assembly, an anti-corrosion washer assembly, a first steel bridge connection plate, and a second steel bridge connection plate. This utility model relates to the field of steel bridge connection structure technology. This fracture-resistant bolt connection pair structure for long-span steel bridges forms a dual stress dispersion structure through a tapered connector between the bolt head and the bolt segment, and four U-shaped stress relief grooves on the bolt segment. This significantly reduces the stress concentration coefficient at the bolt connection, preventing fatigue crack initiation under long-term alternating loads. Simultaneously, the main nut and auxiliary nut, in conjunction with an annular boss, compress the nitrile rubber elastic bushing, continuously compensating for preload attenuation caused by vibration, achieving a preload retention rate of over 90%. This solves the problem of uneven bolt stress caused by loosening of traditional nuts. It ensures the fracture-resistant performance of the bolt connection pair from both "fatigue resistance" and "loosening prevention" dimensions, meeting the core stress requirements of long-span steel bridges.

Description

Technical Field

[0001] This utility model relates to the field of steel bridge connection structure technology, specifically to a fracture-resistant bolt connection pair structure for long-span steel bridges. Background Technology

[0002] The reference patent title is: A High-Strength Bolt Connection Pair for Large-Diameter Steel Structures (Authorization Announcement No.: CN216666175U, Authorization Announcement Date: 2022.06.03). It includes a round head, with a smooth rod integrally connected to the bottom end of the round head. A threaded portion is integrally connected to the bottom end of the smooth rod. A limit nut is threadedly connected to the threaded portion. The limit nut has a threaded hole matching the threaded portion. A guide groove is provided at the bottom of the limit nut outside the threaded hole. A positioning block is provided at the bottom end of the threaded portion. A threaded head is provided on the positioning block. A threaded cavity matching the threaded head is provided at the bottom end of the threaded portion. Symmetrical elastic positioning structures are provided on the positioning block. The elastic positioning structure includes a connecting cylinder fixed to the positioning block. The advantages are: this device has a simple structure and is easy to use. After the bolt is fixed by the limit nut, secondary tightening ensures that the limit nut is not easily dislodged during use, increasing the strength and stability of the connection.

[0003] Based on the aforementioned documents: existing long-span steel bridges daily need to withstand complex loads such as vehicle impacts, wind vibrations, and temperature changes. The bolted connections at their joints are the core load-bearing components, and existing bolted connections have the following technical defects:

[0004] 1. The connection between the bolt head and the bolt section is often a right angle or a simple transition, resulting in significant stress concentration. Under long-term alternating loads, fatigue cracks are easily initiated, eventually leading to bolt breakage.

[0005] 2. Anti-loosening structures often use single nuts or ordinary double nuts. The preload is easily attenuated by vibration, leading to loosening of the connection and further aggravating uneven stress on the bolts.

[0006] 3. The friction between the washer and the steel bridge connecting plate is insufficient, and the anti-corrosion coating system is imperfect. It is prone to corrosion and failure in outdoor humid and salty environments, which shortens the service life of the connection pair. Therefore, this utility model provides a fracture-resistant bolt connection pair structure for long-span steel bridges. Utility Model Content

[0007] To address the shortcomings of existing technologies, this utility model provides a fracture-resistant bolt connection pair structure for long-span steel bridges, which solves the problems of stress concentration, preload attenuation, and corrosion failure in existing bolt connection pairs.

[0008] To achieve the above objectives, this utility model is implemented through the following technical solution: a fracture-resistant bolt connection pair structure for long-span steel bridges, comprising a bolt body, an anti-loosening nut assembly, an anti-corrosion washer assembly, a first steel bridge connection plate, and a second steel bridge connection plate. The bolt body includes a bolt head, a bolt section, and a threaded section. A tapered connector is integrally formed at the connection between the bolt head and the bolt section. A stress relief groove is formed on the outer surface of the bolt section. A 45° chamfer is provided at the tail end of the threaded section.

[0009] The anti-loosening nut assembly includes a main nut and a secondary nut. The bottom of the main nut has an annular groove, and the top of the secondary nut has an annular boss that matches the annular groove.

[0010] Preferably, an elastic bushing is provided between the annular groove and the annular boss, and the elastic bushing is made of nitrile rubber.

[0011] Preferably, the stress relief groove is a U-shaped groove, and four stress relief grooves are evenly arranged along the circumference of the screw section.

[0012] Preferably, the anti-corrosion washer assembly includes a first washer and a second washer. The first washer is disposed between the main nut and the first steel bridge connecting plate, and the second washer is disposed between the bolt head and the second steel bridge connecting plate. The top of the first washer and the bottom of the second washer are provided with multiple sets of anti-slip teeth.

[0013] Preferably, the top of the second washer is provided with a tapered groove, which is adapted to the tapered connector.

[0014] Preferably, the bolt body, main nut, and auxiliary nut are all made of high-strength alloy structural steel and coated with zinc-aluminum alloy. The first washer and the second washer are made of 304 stainless steel and coated with polytetrafluoroethylene.

[0015] Beneficial effects

[0016] This utility model provides a fracture-resistant bolt connection pair structure for long-span steel bridges. Compared with the prior art, it has the following advantages:

[0017] 1. This anti-fracture bolt connection pair structure for long-span steel bridges forms a dual stress dispersion structure through a tapered connector between the bolt head and the bolt section, and four U-shaped stress relief grooves on the bolt section. This significantly reduces the stress concentration coefficient at the bolt connection, preventing fatigue crack initiation under long-term alternating loads. At the same time, the main nut and auxiliary nut, together with the annular boss, compress the nitrile rubber elastic bushing, which can continuously compensate for the preload attenuation caused by vibration. The preload retention rate is over 90%, solving the problem of uneven bolt stress caused by loosening of traditional nuts. It ensures the anti-fracture performance of the bolt connection pair from the dual dimensions of "fatigue resistance" and "loosening prevention", meeting the core stress requirements of long-span steel bridges.

[0018] 2. This anti-fracture bolt connection pair structure for long-span steel bridges addresses the shortcomings of existing technologies, such as incomplete anti-corrosion coatings and insufficient gasket friction. The bolt body, main nut, and secondary nut are coated with zinc-aluminum alloy, while the first and second washers are made of 304 stainless steel with a polytetrafluoroethylene coating, forming a dual anti-corrosion system. It can withstand salt spray corrosion for over 1200 hours, making it suitable for the humid and salt-corrosion environment of steel bridges outdoors. Furthermore, the conical groove of the second washer contacts the conical connecting surface for force transmission, and the anti-slip serrations of the washer prevent local crushing and enhance the friction with the steel bridge connecting plate, ensuring uniform transmission of preload and further extending the overall service life of the connection pair. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the external structure assembly of this utility model;

[0020] Figure 2 This is an exploded view of the external structure of this utility model;

[0021] Figure 3 This is a three-dimensional structural diagram of the bolt body of this utility model;

[0022] Figure 4 This is an exploded structural diagram of the anti-loosening nut assembly and anti-corrosion washer assembly of this utility model.

[0023] In the diagram: 1-bolt body, 11-bolt head, 12-screw section, 13-threaded section, 14-tapered connector, 15-stress relief groove, 16-chamfer, 2-anti-loosening nut assembly, 21-main nut, 22-secondary nut, 23-annular groove, 24-annular boss, 3-anti-corrosion washer assembly, 31-first washer, 32-second washer, 33-anti-slip teeth, 4-first steel bridge connecting plate, 5-second steel bridge connecting plate, 6-elastic bushing, 7-tapered groove. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Please see Figure 1-4 This utility model provides a technical solution:

[0026] Based on the anti-fracture bolt connection pair structure for long-span steel bridges, it includes a bolt body 1, an anti-loosening nut assembly 2, an anti-corrosion washer assembly 3, a first steel bridge connecting plate 4, and a second steel bridge connecting plate 5. The bolt body 1 includes a bolt head 11, a screw section 12, and a threaded section 13. A tapered connector 14 is integrally formed at the connection between the bolt head 11 and the screw section 12. A stress relief groove 15 is opened on the outer surface of the screw section 12. A 45° chamfer 16 is provided at the tail end of the threaded section 13.

[0027] The anti-loosening nut assembly 2 includes a main nut 21 and a secondary nut 22. The bottom of the main nut 21 is provided with an annular groove 23, and the top of the secondary nut 22 is integrally formed with an annular boss 24 that matches the annular groove 23.

[0028] The tapered connector 14 between the bolt head 11 and the bolt section 12, along with the four U-shaped stress relief grooves 15 of the bolt section 12, forms a dual stress dispersion structure, significantly reducing the stress concentration coefficient at the bolt joint and preventing fatigue crack initiation under long-term alternating loads. At the same time, the main nut 21 and the auxiliary nut 22, in conjunction with the annular boss 24, compress the nitrile rubber elastic bushing 6, which can continuously compensate for the preload attenuation caused by vibration, achieving a preload retention rate of over 90%. This solves the problem of uneven bolt stress caused by loosening of traditional nuts, ensuring the anti-fracture performance of the bolt connection pair from both "fatigue resistance" and "loosening prevention" dimensions, thus meeting the core stress requirements of long-span steel bridges.

[0029] In this embodiment, an elastic bushing 6 is provided between the annular groove 23 and the annular boss 24, and the elastic bushing 6 is made of nitrile rubber.

[0030] The thickness of the elastic bushing 6 is 2-3mm;

[0031] In this embodiment, the stress relief groove 15 is a U-shaped groove, and four stress relief grooves 15 are evenly arranged along the circumference of the screw section 12.

[0032] U-shaped stress relief groove 15, groove depth 1-1.5mm, groove width 2-2.5mm;

[0033] In this embodiment, the anti-corrosion washer assembly 3 includes a first washer 31 and a second washer 32. The first washer 31 is disposed between the main nut 21 and the first steel bridge connecting plate 4, and the second washer 32 is disposed between the bolt head 11 and the second steel bridge connecting plate 5. The top of the first washer 31 and the bottom of the second washer 32 are provided with multiple sets of anti-slip teeth 33.

[0034] In this embodiment, a tapered groove 7 is provided on the top of the second washer 32, and the tapered groove 7 is adapted to the tapered connector 14.

[0035] In this embodiment, the bolt body 1, the main nut 21 and the secondary nut 22 are all made of high-strength alloy structural steel and are coated with zinc-aluminum alloy. The first washer 31 and the second washer 32 are made of 304 stainless steel and are coated with polytetrafluoroethylene.

[0036] The bolt body 1, the main nut 21 and the auxiliary nut 22 are all made of 42CrMo high-strength alloy structural steel;

[0037] Zinc-aluminum alloy coating thickness 50-80μm; polytetrafluoroethylene coating thickness 20-30μm;

[0038] To address the shortcomings of existing technologies, such as imperfect anti-corrosion coatings and insufficient gasket friction, the bolt body 1, main nut 21, and auxiliary nut 22 are coated with zinc-aluminum alloy, while the first washer 31 and second washer 32 are coated with 304 stainless steel and polytetrafluoroethylene, forming a dual anti-corrosion system. This system provides over 1200 hours of salt spray corrosion resistance, making it suitable for the humid and salt-corrosion environment of steel bridges outdoors. Furthermore, the conical groove 7 of the second washer 32 contacts the conical connector 14 to transmit force, and the anti-slip teeth 33 of the washer not only prevent local crushing but also enhance the friction with the steel bridge connecting plate, ensuring uniform transmission of preload and further extending the overall service life of the connection pair.

[0039] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0040] The specific assembly steps are as follows:

[0041] S1. Stack the second steel bridge connecting plate 5 and the first steel bridge connecting plate 4 together, and align the bolt holes;

[0042] S2. Insert the second washer 32 into the bolt body 1 so that the tapered groove 7 fits with the tapered connector 14. Then, insert the bolt section 12 of the bolt body 1 through the bolt hole opened on the surface of the two plates so that the bottom of the second washer 32 contacts the second steel bridge connecting plate 5.

[0043] S3. Insert the first washer 31 so that its top contacts the first steel bridge connecting plate 4;

[0044] S4. First, screw in the main nut 21 to the preset torque (400 N·m), then screw in the auxiliary nut 22 until the annular boss 24 completely compresses the elastic bushing 6 to complete the assembly.

[0045] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0046] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fracture-proof bolt connection pair structure based on a large-span steel bridge, comprising a bolt body (1), a lock nut assembly (2), a corrosion-resistant washer assembly (3), a first steel bridge connecting plate (4) and a second steel bridge connecting plate (5), characterized in that: The bolt body (1) includes a bolt head (11), a screw rod segment (12) and a threaded segment (13), a tapered connector (14) is integrally formed at the joint of the bolt head (11) and the screw rod segment (12), a stress relief groove (15) is formed on the outer surface of the screw rod segment (12), and a 45° chamfer (16) is arranged at the tail end of the threaded segment (13); The anti-loose nut assembly (2) includes a main nut (21) and a secondary nut (22), an annular groove (23) is formed at the bottom of the main nut (21), and an annular boss (24) is integrally formed at the top of the secondary nut (22) and matched with the annular groove (23).

2. The break-resistant bolted connection pair structure for a long-span steel bridge according to claim 1, characterized by: An elastic bushing (6) is arranged between the annular groove (23) and the annular boss (24), and the elastic bushing (6) is made of nitrile rubber.

3. The break-resistant bolted connection pair structure for a long-span steel bridge according to claim 1, characterized by: The stress relief groove (15) is a U-shaped groove, and four stress relief grooves (15) are evenly arranged along the circumference of the screw rod segment (12).

4. The break-resistant bolted connection pair structure for a long-span steel bridge according to claim 1, characterized by: The corrosion-resistant washer assembly (3) includes a first washer (31) and a second washer (32), the first washer (31) is arranged between the main nut (21) and the first steel bridge connecting plate (4), the second washer (32) is arranged between the bolt head (11) and the second steel bridge connecting plate (5), and a plurality of anti-slip tooth patterns (33) are arranged on the top of the first washer (31) and the bottom of the second washer (32).

5. The break-resistant bolted connection pair structure for a long-span steel bridge according to claim 4, characterized by: A tapered groove (7) is formed at the top of the second washer (32), and the tapered groove (7) is matched with the tapered connector (14).

6. The break-resistant bolted connection pair structure for a long-span steel bridge according to claim 4, characterized by: The bolt body (1), the main nut (21) and the secondary nut (22) are made of high-strength alloy structural steel, and the surface is sprayed with a zinc-aluminum alloy coating, the first washer (31) and the second washer (32) are made of 304 stainless steel, and the surface is sprayed with a polytetrafluoroethylene coating.

Images