Double-rib longitudinal rib and bridge deck structure

Abstract

The present application discloses a longitudinal rib and a welding structure with a top plate, which solves the problem that the longitudinal rib and the top plate through-length straight weld in the prior art are prone to fatigue cracking. The key points of the technical solution are to provide a longitudinal rib, the longitudinal rib includes at least one web, the upper edge of the web has an ear plate folded to one side, the web and the ear plate have a rotation angle β, 90°≤β<134°; the outer end of the ear plate is an outer edge, the side length of the outer edge is greater than the longitudinal length of the longitudinal rib, and at the same time, a welding structure of the longitudinal rib and the top plate is provided, which increases the virtual width of the weld, and because there are welds in the longitudinal and transverse directions in the plane, the weld's ability to withstand complex isotropic loads is improved, and the weld is located at the outer edge, away from the stress sensitive area, which greatly reduces the probability of fatigue cracking of the weld.

Description

Technical Field

[0001] The present application relates to the field of orthotropic bridge deck structures, and in particular to a novel longitudinal rib and bridge deck structure. Background Art

[0002] Orthotropic bridge deck structure is a type of plate structure that mainly connects the top plate, longitudinal ribs and transverse rib diaphragms through welding to meet different force requirements in the longitudinal and transverse directions. The longitudinal stiffness requirement is large, so the longitudinal ribs are arranged in the longitudinal direction. The transverse stiffness requirement is relatively small, and a transverse rib diaphragm is arranged at a certain distance to achieve the purpose of reducing the deadweight of the structure. Orthotropic bridge deck structure is widely used in bridge deck systems, especially long-span bridges, due to its advantages such as light deadweight and large bearing capacity.

[0003] Although orthotropic bridge deck structures have many advantages, their fatigue cracking problem has always been difficult to solve. How to improve the durability of orthotropic bridge deck structures and solve the fatigue problem has long been a technical issue and research hotspot that has received much attention, and its technical and economic rationality is even more of a difficult problem that plagues the design.

[0004] A large number of studies have shown that the structural form of the stiffener longitudinal ribs and transverse ribs and the welding structural details are the main causes of fatigue problems.

[0005] The two main forms of longitudinal ribs include open ribs and closed ribs. Closed ribs have higher anti-interference and torsional stiffness. The higher torsional stiffness enables closed ribs to better transfer concentrated lateral loads, thereby reducing the stress on the bridge deck. In addition, closed ribs also have the advantages of fewer welds, less torsion, and less steel.

[0006] Since the closed rib system forms a closed inner cavity with the top plate, partial penetration welding of the longitudinal rib and the panel is often used during welding. Usually, a 75% penetration rate is maintained. Since the thickness of the longitudinal rib itself is only about 6-8mm, it is difficult to control the accuracy during welding to ensure the 1.5-2mm un-penetrated portion. In practice, it is often easy to weld through or fail to achieve the required penetration rate. In addition, the initial un-penetrated portion is the initial crack. This welding method is prone to induce fatigue cracking. The un-penetrated portion is on the inner side of the longitudinal rib, and even if cracks occur, it is difficult to detect. Therefore, manufacturers are required to consistently maintain high quality during manufacturing.

[0007] Secondly, due to the geometry and inherent torsional strength of closed ribs, closed rib bridge decks are prone to local deformation and stress, e.g. Figure 1 The bridge deck structure shown, including the top plate 200, the longitudinal ribs 100 and the transverse diaphragms 300, is a typical deformation diagram of the traditional closed rib at the intersection of the longitudinal ribs and the transverse ribs, i.e., the fulcrum position, when subjected to wheel loads. The longitudinal ribs are constantly deformed by bulging, twisting, etc., which can easily cause fatigue cracking at the welds between the longitudinal ribs and the top plate and at the connections between the longitudinal ribs and the transverse ribs.

[0008] Secondly, in the closed rib bridge deck system, the closed ribs are usually arranged with equal horizontal spacing, so the bridge deck width is theoretically required to be an integer multiple of the effective width, but in fact it is difficult to do so.

[0009] There are two main disadvantages to the open rib system. First, its torsional stiffness is poorer than that of the closed rib, which means that it is not very efficient in transferring transverse loads such as wheel loads between ribs. This will result in more longitudinal ribs being required and less transverse rib spacing, thus requiring more steel per square foot than the closed rib. Second, the total amount of welding required for the open rib system is also about twice that of the closed rib, that is, a pair of vertical open ribs and panels requires four welds, while the corresponding closed rib only requires two welds.

[0010] How to construct high-performance ribs and improve the welding structure between longitudinal ribs and top plates is one of the key directions in studying the fatigue problem of steel bridge decks. Summary of the invention

[0011] In order to address the defects of existing longitudinal ribs and steel bridge decks with poor fatigue resistance, the present application provides a new type of double-rib longitudinal rib and a bridge deck structure using the longitudinal rib. By adopting ear plate connection, the strain on one side is released and the fatigue resistance is improved. At the same time, the other side of the ear plate utilizes the connection of adjacent closed ribs, that is, open ribs are added as secondary ribs without increasing the number of connections, thereby further strengthening the structure.

[0012] In order to achieve the above objectives, this application adopts the following technical solutions:

[0013] On the one hand, the present application provides a double-rib longitudinal rib, including a closed rib, an open rib and an ear plate, wherein the closed rib and the open rib are connected by the ear plate, and the closed rib, the open rib and the ear plate are made of a single material; the closed rib has a side web, one end of the ear plate is connected to the upper end of the side web, and the ear plate and the side web have a first angle α; the outer contour radius of the first angle α is R1, the inner contour radius is R2, the thickness of the ear plate is t, R1-R2<t; the open rib is connected to the other end of the ear plate, and the open rib and the ear plate have a second angle θ; the ear plate has a plurality of connecting holes. By reducing the gap between the outer corner radius and the inner corner radius of the first corner (normally 1 times the plate thickness), the gap is continuously reduced, which is beneficial to the corner bearing force performance, and even adopting a reverse design in which the outer contour radius is equal to or less than the inner contour radius, the generation of additional bending moment of the longitudinal rib side web is effectively avoided, so that the longitudinal rib can use the corner to bear the strain during loading without generating out-of-plane deformation.

[0014] Preferably, ear plates and open ribs are provided on both sides of the closed rib. This structure is more symmetrical, which is equivalent to adding two open ribs on both sides of the closed longitudinal rib, significantly improving its longitudinal bending and torsional stiffness, extending the longitudinal bridge stress influence line, and making the longitudinal force transmission performance of the longitudinal rib better. At the same time, the addition of secondary ribs here and the connection of adjacent closed ribs, that is, without increasing the number of connections, further strengthens the structure. Thirdly, by extending the ear plates outward, the connection point between the longitudinal rib and the top plate is moved outward, and the actual span of the top plate is reduced. Therefore, the use of a thin top plate can also achieve a large longitudinal rib orthotropic bridge deck structure, and the overall steel consumption is reduced.

[0015] Preferably, the ratio of the height of the side web to the plate thickness is greater than 40. Through the local reinforcement of the longitudinal rib structure and the characteristic that the forming angle of the parent material is insensitive to the rotation of the longitudinal rib, the ratio of the height of the longitudinal rib side web to the plate thickness can break through the limitation of the traditional height-to-thickness ratio of 40, improve the cross-sectional inertia moment of the longitudinal rib, reduce the number of longitudinal ribs, and thus reduce the number of welds.

[0016] Preferably, the width of the ear plate is L, 30mm≤L≤100mm. The above ear plate width can not only ensure sufficient connection strength between the longitudinal rib and the top plate, but also achieve a better cost-effectiveness in terms of steel consumption and longitudinal rib stiffness performance in combination with the actual orthotropic steel bridge deck.

[0017] Preferably, the opening rib height h is ≥ 10 mm.

[0018] Preferably, the opening rib has a lower flange, which is formed by folding the lower end of the opening rib. By folding the lower flange, the manufacturing is simple and the section moment of inertia of the opening rib is further improved, thereby increasing the bending and torsion resistance of the entire longitudinal rib.

[0019] On the other hand, the present application provides a bridge deck structure, including a top plate and the above-mentioned longitudinal ribs, wherein the ear plate is attached to and fixedly connected to the bottom surface of the top plate.

[0020] Preferably, a connecting piece is further included, wherein the connecting piece matches the connecting hole, and the ear plate is fixedly connected to the top plate via the connecting piece.

[0021] Preferably, the connecting member is a bolt. Bolt connection has a high degree of industrialization and assembly, and is particularly suitable for steel-concrete composite bridge deck structures. Concrete is poured on the upper part of the top plate and the bolts are fixed at the same time, which not only prevents the bolts from loosening, but also improves the bonding degree between the concrete and the top plate.

[0022] Preferably, the connecting piece is a friction welding nail. Non-welding methods such as bolt connection require holes in the top plate. Since the top plate is a component that directly bears the load, the holes will greatly weaken its rigidity. Rotating friction welding nails are used in the connection holes to connect the longitudinal ribs to the top plate, without the need to open holes in the top plate, which is particularly suitable for steel bridge deck structures. At the same time, friction welding has a higher degree of industrialization and assembly, and the welding quality does not depend on uncontrollable factors such as the level of workers. The welding quality is more stable, and the strength of friction welding is high, which is particularly suitable for harsh stress environments.

[0023] Preferably, the ear plate is fixedly connected to the top plate by fusion welding in the connection hole. Although the strength of traditional plug welding or fusion welding is not as good as friction welding, friction welding usually requires special equipment and is suitable for welding in a workshop. Traditional fusion welding and other equipment are simple and suitable for on-site operations, and are therefore suitable for application scenarios such as the later maintenance of the longitudinal rib.

[0024] Compared with the prior art, the longitudinal ribs and the welding structure with the top plate using the above technical solution have the following beneficial effects:

[0025] 1. The present application forms a semi-constrained structure on one side of the overall closed rib through connection on the ear plate, and uses the non-welded parent material forming corner to bear the rotational stress, so that the strain on this side is released on the one hand. Since the closed rib is an integral section connected on both sides, the strain on the other side of the closed rib is further partially released, thereby balancing and partially offsetting the stress and strain on the inside and outside of the rib wall of the closed rib. Since the two rib walls of the closed rib are interconnected through the bottom, the stress and fatigue of the rib wall on the other side are objectively reduced.

[0026] 2. By adding open ribs as secondary ribs, the longitudinal stiffness is significantly improved, the longitudinal bridge stress influence line is extended, the longitudinal force transmission performance of the longitudinal rib is better, and the optimal range of material usage and molding workload is taken into account. The connection of adjacent closed ribs is used to strengthen the structure without increasing the number of connections, thereby achieving high performance at a lower cost.

[0027] 3. In addition, while the bridge deck width is theoretically required to be an integer multiple of the effective width of the longitudinal rib, it is actually difficult to achieve this. When an integer number of closed ribs cannot be accommodated, the innovative double-rib longitudinal rib structure of the present application can effectively solve this problem.

[0028] 4. The ear plate connection not only diversifies the connection methods, but also can be connected by welding or bolts. At the same time, a connection hole is opened in the middle of the ear plate to connect with the top plate, and the connection position of the traditional longitudinal rib and the top plate is transferred outward from the corner between the longitudinal rib side web and the top plate. The weld at the corner position is replaced by a formed corner formed by bending the parent material, and the deformation of the parent material replaces the force of the fillet weld, which has stronger fatigue resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the deformation diagram of the longitudinal rib in the traditional structure under repeated wheel loads;

[0030] Figure 2 This is a schematic structural diagram of the double-rib longitudinal ribs of Example 1 of the present application;

[0031] Figure 3 It is a schematic plan view of the transverse bridge direction of the double-rib type longitudinal rib of Example 1 of the present application;

[0032] Figure 4 for Figure 3 A partial enlarged view of

[0033] Figure 5 It is a schematic diagram of a bridge deck structure including double-rib longitudinal ribs in Example 1 of the present application;

[0034] Figure 6 for Figure 5 A schematic plan view of the bridge deck structure in the transverse direction of the bridge;

[0035] Figure 7 This is a schematic diagram of the three-dimensional structure of the double-rib type longitudinal ribs in Example 2 of the present application;

[0036] Figure 8 It is a schematic plan view of the transverse bridge direction of the double-rib type longitudinal rib of Example 3 of the present application;

[0037] Fig. 9 for Figure 8 A partial enlarged view of

[0038] Fig.10 This is a schematic diagram of the combined bridge deck structure in Example 3 of the present application.

[0039] Reference numerals:

[0040] 1. Double-rib type longitudinal rib; 11. Closed rib; 111. Side web; 112. Bottom edge; 12. Open rib; 121. Lower flange; 13. Ear plate; 131. Connecting hole; 2. Top plate; 100. Prior art longitudinal rib; 200. Prior art top plate; 300. Prior art transverse rib. DETAILED DESCRIPTION

[0041] The present application is further described below in conjunction with the accompanying drawings. It should be noted that in the description of the present application, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present application.

[0042] Embodiment 1:

[0043] like Figure 2 , 3 As shown, embodiment 1 of the present application is a double-rib type longitudinal rib 1, comprising a closed rib 11, an open rib 12 and an ear plate 13, wherein the closed rib 11 and the open rib 12 are connected by the ear plate 13. The closed rib 11 comprises a pair of symmetrical side webs 111 and a bottom edge 112 connecting the lower ends of the pair of side webs 111. The upper end of the side web 111 on one side of the closed rib 11 has an outwardly folded ear plate 13, one end of the ear plate 13 is connected to the upper end of the side web 111, and the other end is connected to the upper end of the open rib 12, and the ear plate 13 has a plurality of connection holes 131 along the length direction of the longitudinal rib 1. Figure 4 As shown, the ear plate 13 and the side web plate 111 have a first rotation angle α, and 90°≤α≤135°, the opening rib 12 is formed by folding the outer end of the ear plate 13, and the opening rib 12 and the ear plate 13 have a second rotation angle θ, and 80°<θ<120°.

[0044] like Figure 2 , 3 As shown, the longitudinal rib 1 is formed by bending or rolling a steel plate, and the closed rib 11, the open rib 12 and the ear plate 13 are made of an integral material. As is known to all, steel sections and the like are hot rolled, and steel structures of various cross sections can be rolled from steel billets. However, the longitudinal ribs used in bridges are usually customized products, unlike the standardized products such as steel sections, which are in large quantities. It is not feasible to invest a lot of equipment costs in the actual production and operation of the longitudinal ribs. Therefore, bending or rolling steel plates is more suitable for realizing continuous production of longitudinal ribs with a large longitudinal length on the production line, which is low cost and high efficiency.

[0045] Figure 5 , 6 As shown, a bridge deck structure using double-rib longitudinal ribs 1 includes a top plate 2 and double-rib longitudinal ribs 1, and the double-rib longitudinal ribs 1 are fixedly connected to the top plate 2 by welding. The side web 111 on one side of the closed rib 11 is welded to the top plate 2 by conventional single-sided welding or double-sided welding; on the other side of the closed rib 11, the upper surface of the ear plate 13 is fitted with the lower surface of the top plate 2, and the other side of the longitudinal rib 1 is connected to the top plate 2 by arranging a connector 3 in the connection hole 131 of the ear plate 13.

[0046] like Figure 5 , 6As shown, the connector 3 is a friction welding pin, which is driven to rotate at high speed to melt the metal in the contact area, solidify after cooling, and form a friction welding connection between the longitudinal rib 1 and the top plate 2. At the same time, friction welding has a higher degree of industrialization and assembly, and the welding quality does not depend on uncontrollable factors such as the level of workers. The welding quality is more stable, and the strength of friction welding is high, which is especially suitable for harsh stress environments. Especially in orthogonal anisotropic steel bridge deck structures, since the top plate 2 is a component that directly bears the load, the opening of the top plate 2 will greatly weaken its stiffness. The use of friction welding can achieve the connection strength without opening holes in the top plate 2, thereby ensuring the integrity and stiffness of the top plate 2.

[0047] Of course, traditional fusion welding plug welding can also be performed in the connecting hole 131 to fix the longitudinal rib to the lower surface of the top plate 2, without opening a hole in the top plate 2 or adding a connecting piece 3. Although traditional plug welding or fusion welding is not as strong as friction welding, friction welding usually requires special equipment and is suitable for welding in a workshop. Traditional fusion welding and other equipment are simple and suitable for on-site operations, and are therefore suitable for application scenarios such as later maintenance of the longitudinal rib.

[0048] like Figure 4 ,0The width L of the ear plate 13 is preferably 30mm-100mm. If the ear plate 13 is less than 30mm, the corresponding connecting hole 131 is too small and the welding area is too small, resulting in insufficient connection strength between the longitudinal rib 1 and the top plate 2. Combined with the actual orthotropic steel bridge deck, the spacing between adjacent longitudinal ribs and adjacent webs is usually about 300mm. The width of the ear plate 13 determines the spacing of the open ribs 12 and is also related to the spacing of the open ribs 12. If the width of the ear plate 13 is too large, it cannot achieve a good cost-effectiveness in terms of steel consumption and longitudinal rib stiffness performance.

[0049] like Figure 1 From the deformation diagram of the traditional longitudinal rib 100 under repeated wheel loads, it can be seen that the intersection of the side web of the traditional longitudinal rib 100 and the top plate 200 is a stress-sensitive area, which is mainly subjected to the local bending and pulling compound action caused by the wheel load perpendicular to the top plate. The opening and closing angle φ between the side web of the longitudinal rib and the top plate is constantly changing under the action of the wheel load. The weld between the traditional longitudinal rib 100 and the top plate 200 is located there. The large out-of-plane deformation between the longitudinal rib and the panel under the action of the local wheel load causes a higher local bending stress in the weld there. The initial welding defect further amplifies the stress concentration effect and eventually causes fatigue cracking in this structural detail. In the embodiment of the present application, an ear plate 13 is set on one side, and a connecting hole is opened in the middle of the ear plate 13 to connect with the top plate 2, so that the connection position of the traditional longitudinal rib and the top plate is transferred outward from the corner between the side web of the longitudinal rib and the top plate. The weld at the corner position is replaced by a formed corner formed by bending the parent material, and the deformation of the parent material is replaced. Figure 1 The stress of the middle fillet weld is as follows: Figure 6As shown by the dotted line, the deformation of the base material at the forming corner releases the stress on one side, thereby reducing the stress and stress amplitude of the weld and improving the fatigue resistance of the connection between the longitudinal rib and the top plate.

[0050] Embodiment 2:

[0051] like Figure 7 , 8 As shown, Example 2 of the present application provides another double-rib longitudinal rib 1 of a bridge deck structure, which is different from Example 1 in that ear plates 13 and open ribs 12 are provided on both sides of the closed rib 11 of the longitudinal rib 1.

[0052] In Example 2 of the present application, without increasing the amount of welding, the two side webs 111 of the closed rib 11 are bent twice in succession to form ear plates 13 and open ribs 12, which is equivalent to adding two open ribs on both sides of the closed longitudinal rib 1, significantly improving its longitudinal bending and torsional stiffness, extending the longitudinal bridge stress influence line, and making the longitudinal force transmission performance of the longitudinal rib 1 better.

[0053] In the bridge deck structure using the longitudinal rib 1, since the side webs 111 on the adjacent sides of two adjacent longitudinal ribs 1 extend outwardly with ear plates 13, the actual span of the top plate 2 between the two adjacent longitudinal ribs 1 is: the web spacing on both sides of the adjacent longitudinal ribs - 2 times the width of the ear plates. The wider the ear plates 13, the smaller the span of the top plate 2, which improves the stiffness in the transverse direction of the bridge. Especially for large-sized longitudinal ribs, as the size of the longitudinal ribs increases, the center spacing of adjacent longitudinal ribs increases, resulting in the top plate to meet the span-thickness ratio requirements, and the top plate needs to be thickened accordingly. With the longitudinal ribs with wide ear plates, the top plate does not need to be thickened or only needs to be thickened a little. The thin top plate can also achieve a large longitudinal rib orthotropic bridge deck structure, and the overall steel consumption is reduced.

[0054] like Fig. 9 As shown, by local upsetting and other methods, the difference between the outer contour radius R1 and the inner contour radius R2 of the first corner is made less than one times the plate thickness t of the ear plate 13. Under normal circumstances, the difference between the inner and outer radii of the bent steel plate corner is 1 times the plate thickness t. Since a large angle will cause additional bending moment of the longitudinal rib side web 112, when the longitudinal rib is compressed, it will cause the side web to buckle or become unstable. This application effectively avoids the generation of additional bending moment of the rib by reducing the difference between the outer contour radius R1 and the inner contour radius R2 of the first corner, so that the longitudinal rib can use the corner to bear the strain during loading without generating out-of-plane deformation. Through local reinforcement, it further plays the role of a thinner rib supporting a higher stiffening rib. The ratio of the height of the longitudinal rib side web to the plate thickness is greater than the standard limit of 40, reaching more than 45.

[0055] Embodiment 3:

[0056] like Fig.10As shown, Example 3 of the present application provides a case where a double-rib longitudinal rib 1 is used for a composite structural bridge deck. The closed rib 11 is a trapezoidal cross-section, and the open rib 12 has a lower flange 121, which is formed by folding the lower end of the open rib 12. The setting of the lower flange 121 further increases the section inertia moment of the open rib 12, thereby improving the bending and torsion resistance of the open rib 12. A reinforced concrete layer is laid on the upper surface of the top plate 2, and a connector 3 is arranged in the connection hole 131 of the ear plate 13. The connector 3 is a high-strength bolt, which is connected to the top plate 2 by bolt connection. It not only has a high degree of industrialization and assembly, but also the upper part of the bolt is anchored to the concrete, which is particularly suitable for steel-concrete composite bridge deck structures.

[0057] The above is a preferred implementation of the present application. A person skilled in the art may make several modifications and improvements without departing from the principle of the present application, and these modifications and improvements shall also be deemed as within the protection scope of the present application.

Claims

1. A double-rib longitudinal rib (1), characterized in that: It comprises a closed rib (11), an open rib (12) and an ear plate (13), wherein the closed rib (11) and the open rib (12) are connected via the ear plate (13), and the closed rib (11), the open rib (12) and the ear plate (13) are made of a single piece of material; The closed rib (11) has a side web (111), one end of the ear plate (13) is connected to the upper end of the side web (111), and the ear plate (13) and the side web (111) have a first rotation angle α; the outer contour radius of the first rotation angle α is R1, the inner contour radius is R2, the plate thickness of the ear plate (13) is t, and R1-R2<t; The opening rib (12) is connected to the other end of the ear plate (13), and the opening rib (12) and the ear plate (13) have a second rotation angle θ; The ear plate (13) is provided with a plurality of connection holes (131).

2. The double-rib longitudinal rib (1) according to claim 1, characterized in that: Ear plates (13) and open ribs (12) are arranged on both sides of the closed rib (11).

3. The double-rib longitudinal rib (1) according to claim 1, characterized in that: The ratio of the height to the plate thickness of the side web (111) is greater than 40.

4. The double-rib longitudinal rib (1) according to claim 1, characterized in that: The width of the ear plate (13) is L, 30mm≤L≤100mm.

5. The double-rib longitudinal rib (1) according to claim 1, characterized in that: The opening rib (12) has a height h, where h≥10 mm.

6. The double-rib longitudinal rib (1) according to claim 1, characterized in that: The opening rib (12) has a lower flange (121), and the lower flange (121) is formed by folding the lower end of the opening rib (12).

7. A bridge deck structure, comprising a top plate (2) and a double-rib longitudinal rib (1) according to any one of claims 1 to 6, characterized in that: The ear plate (13) is attached to and fixedly connected to the bottom surface of the top plate (2).

8. The bridge deck structure according to claim 7, characterized in that: It also comprises a connecting piece (3), wherein the connecting piece (3) matches the connecting hole (131), and the ear plate (13) is fixedly connected to the top plate (2) via the connecting piece (3).

9. The bridge deck structure according to claim 8, characterized in that: The connecting piece (3) is a bolt.

10. The bridge deck structure according to claim 8, characterized in that: The connecting piece (3) is a friction welding nail.

11. The bridge deck structure according to claim 7, characterized in that: The ear plate (13) is fixedly connected to the top plate (2) by welding in the connection hole (131).

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