Simply-supported-to-continuous structure of multi-span hole small bridge cover plate

Abstract

The utility model belongs to the technical field of highway bridge and culvert engineering, and discloses a multi-span hole small bridge covering plate simply-supported-to-continuous structure which comprises a base, a side wall, a middle wall and a plurality of cover plates. According to the middle wall structure, the boss is arranged at the top end of the middle wall in the width direction of the base, the supporting stability of the middle wall to the cover plate is enhanced, the wall body thickness of the middle wall can be properly reduced so as to reduce the influence on a water cross section, the drainage capacity of a culvert is improved, the cost can be reduced, and water flow can be kept smooth. The cast-in-place connecting area is reserved between the adjacent cover plates, so that the embedded steel bar assemblies embedded in the cover plates can be welded and connected in the area, an integrated continuous structure is formed in combination with subsequent concrete cast-in-place, the problem of reflection cracks caused by deformation of a simply-supported structure at the top end of the middle wall is effectively solved, and the service life of the middle wall is prolonged. Therefore, the overall structural performance of the pavement is improved, road driving safety and comfort are guaranteed, and the service life of the pavement is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of highway bridge and culvert engineering technology, and in particular to a simple-supported variable continuous structure for a multi-span small bridge with a covered slab. Background Technology

[0002] In highway construction, culverts play a crucial role as indispensable structures. Their main function is to ensure smooth surface traffic while achieving effective underground drainage. Culverts come in various structural forms, commonly including pipe culverts, box culverts, and slab culverts. Among these, slab culverts are widely used due to their simple construction process and strong drainage capacity. In particular, the simply supported slab section can be prefabricated in a factory, greatly reducing on-site work, accelerating construction progress, and contributing to improved overall construction quality.

[0003] In multi-span culvert structures, the spans are typically separated by a central wall, which serves a supporting function. However, to more stably support the top cover plate, the central wall is often oversized, compressing the effective water passage cross-section and reducing the culvert's drainage capacity. Over time, an oversized central wall can easily lead to siltation at the bottom, further raising the upstream water level and affecting drainage. Furthermore, multi-span culverts often use simply supported cover plates, with each span bearing independent stress, lacking overall continuity. Assembly is cumbersome, and due to inconsistent thermal expansion and contraction and load deformation in each span, the joints between the cover plates (span joints) and the connection points between the plates and the central wall easily become stress concentration areas, leading to reflective cracks. As the service life increases, these cracks gradually extend to the road surface, causing surface cracking, which not only affects road driving quality but also accelerates road aging and reduces road lifespan.

[0004] Therefore, there is an urgent need for a multi-span bridge with a simply supported to continuous structure to solve the above problems. Utility Model Content

[0005] The purpose of this invention is to provide a multi-span small bridge with a cover plate that is simply supported and then continuously extended. This structure not only provides stable support for the cover plate structure but also effectively reduces the water-blocking area and improves drainage efficiency. At the same time, it enables rapid assembly of the cover plate, reduces reflective cracks between the cover plates, ensures road driving quality, and extends the service life of the road surface.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] Multi-span bridges encompass simply supported slab structures that transition to continuous structure, including:

[0008] The system comprises a base, two side walls, at least one central wall, and multiple cover plates. The two side walls are disposed on the base and are arranged opposite each other along the length of the base. Each side wall has a positioning groove at its top for supporting the cover plate. At least one central wall is disposed between the two side walls and is arranged parallel to the side walls. Each central wall has a boss at its top along the width of the base for supporting the cover plate.

[0009] Multiple cover plates are respectively installed across the positioning groove of the side wall and the protrusion of the central wall along the width direction of the base; each cover plate includes a cover plate body and a pre-embedded steel reinforcement assembly, the pre-embedded steel reinforcement assembly is disposed inside the cover plate body, and partially extends out of both sides of the cover plate body along the width direction of the base; a cast-in-place connection area is reserved between the top of the protrusion and the adjacent cover plates, the pre-embedded steel reinforcement assemblies of the adjacent cover plates are welded together in the cast-in-place connection area, and can form an integral continuous structure by pouring concrete.

[0010] Furthermore, the top of the boss is provided with multiple positioning steel bars at intervals on both sides along the length direction of the base, and the lower surface of each cover plate body is provided with multiple positioning holes, which can be inserted and engaged with multiple positioning steel bars on one side.

[0011] Furthermore, the circumferential joint between each of the positioning holes and the positioning reinforcing bars can be sealed by grouting.

[0012] Furthermore, the pre-embedded steel reinforcement assembly includes upper main steel reinforcement, upper structural steel reinforcement, lower main steel reinforcement, and lower structural steel reinforcement. The upper main steel reinforcement and the lower main steel reinforcement are respectively positioned opposite each other on the upper and lower parts of the cover plate body and are evenly spaced along the width direction of the base. Both can extend out of the cover plate body along the width direction of the base. The upper main steel reinforcement and the lower main steel reinforcement positioned opposite each other on the cover plate on each protrusion are staggered.

[0013] The upper structural reinforcement is located between the upper main reinforcement and the upper surface of the cover plate body, and the lower structural reinforcement is located between the lower main reinforcement and the lower surface of the cover plate body, and both are arranged at intervals along the length of the base.

[0014] Furthermore, the upper main reinforcing bars arranged alternately between adjacent cover plates on each of the protrusions are welded together one by one along the width direction of the base, so that the cast-in-place connection area forms a negative bending moment zone.

[0015] Furthermore, the cover plate body is densely arranged with multiple upper structural steel bars and multiple lower structural steel bars near the positioning hole.

[0016] Furthermore, the cast-in-place connection area is provided with cast-in-place zone stirrups and cast-in-place zone structural reinforcement bars. The cast-in-place zone stirrups are arranged vertically around the upper main reinforcement bars and the lower main reinforcement bars to form a closed stirrup frame. Multiple cast-in-place zone structural reinforcement bars are arranged along the length of the base.

[0017] Furthermore, the upper surface of each of the said bosses is set as a rough surface; and / or

[0018] Both end faces of each of the cover plates are provided with the roughened surfaces.

[0019] Furthermore, a waterproof layer is placed between the cover plate and the positioning groove of the sidewall; and / or

[0020] The waterproof layer is placed between the cover plate and the protrusion of the central wall.

[0021] Furthermore, multiple cover plates can be arranged side by side along the length of the base.

[0022] The beneficial effects of this utility model are:

[0023] This invention provides a multi-span culvert bridge with a simple-supported to continuous structure, including a base, sidewalls, and multiple cover plates. By setting a protrusion at the top of the middle wall along the width of the base, the contact area between the middle wall and the cover plates is increased, thereby enhancing the support stability of the middle wall for the cover plates. While ensuring the same support effect, this middle wall structure can appropriately reduce the wall thickness, effectively reducing its water-blocking area in water, minimizing the impact on the water passage cross-section, improving the drainage capacity of the culvert, and reducing costs. Simultaneously, it helps reduce the risk of floating debris accumulation at the bottom of the middle wall, maintaining smooth water flow. By reserving a pre-cast connection area between adjacent cover plates, the pre-embedded steel reinforcement components embedded in the cover plates can be welded together in this area, and combined with subsequent concrete casting, forming an integrated continuous structure. This not only transforms the originally relatively independent simple-supported structure into a continuous structure with coordinated stress distribution, but also effectively avoids the problem of reflective cracking caused by deformation of the simply supported structure at the top of the middle wall, thereby improving the overall structural performance of the road surface, ensuring road driving safety and comfort, and extending the service life of the road surface. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the multi-span small bridge covering a simply supported to continuously connected structure in this utility model;

[0025] Figure 2 This is a front view of the connection between the middle wall and the cover plate in this utility model;

[0026] Figure 3 This is a top view of the connection between the middle wall and the cover plate in this utility model.

[0027] In the picture:

[0028] 1. Base; 2. Side wall; 21. Positioning groove; 3. Middle wall; 31. Boss; 32. Positioning reinforcement; 4. Cover plate; 41. Cover plate body; 42. Embedded reinforcement assembly; 421. Upper main reinforcement; 422. Upper structural reinforcement; 423. Lower main reinforcement; 424. Lower structural reinforcement; 43. Positioning hole; 5. Cast-in-place connection area; 51. Stirrups in cast-in-place area; 52. Structural reinforcement in cast-in-place area. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0030] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0033] like Figures 1 to 3As shown, this utility model provides a multi-span small bridge with a simply supported to continuous structure, including a base 1, side walls 2, middle walls 3, and multiple cover plates 4. The side walls 2 are located on the base 1 and are arranged opposite each other along the length of the base 1. Each side wall 2 has a positioning groove 21 at its top for supporting the cover plate 4. The middle walls 3 are arranged parallel to the side walls 2 between them. Each middle wall 3 has a boss 31 at its top along the width of the base 1 for supporting the cover plate 4. The multiple cover plates 4 are arranged along the width of the base 1. The positioning groove 21 of the side wall 2 and the protrusion 31 of the middle wall 3 are respectively installed on the positioning groove 21 of the side wall 2 and the protrusion 31 of the middle wall 3; the cover plate 4 includes the cover plate body 41 and the embedded steel reinforcement assembly 42. The embedded steel reinforcement assembly 42 is located inside the cover plate body 41 and extends out of both sides of the cover plate body 41 along the width direction of the base 1; a cast-in-place connection area 5 is reserved between the top of the protrusion 31 and the adjacent cover plate 4. The embedded steel reinforcement assembly 42 of the adjacent cover plate 4 is welded and connected in the cast-in-place connection area 5, and can form an integral continuous structure by pouring concrete.

[0034] By setting a protrusion 31 at the top of the central wall 3 along the width direction of the base 1, the contact area between the central wall 3 and the cover plate 4 is increased, thereby enhancing the support stability of the central wall 3 for the cover plate 4. Under the premise of ensuring the same support effect, this structural form of the central wall 3 can appropriately reduce the wall thickness of the central wall 3, thereby effectively reducing its water-blocking area in water, reducing the impact on the water passage section, improving the drainage capacity of the culvert, and reducing costs. At the same time, it helps to reduce the risk of floating debris accumulating at the bottom of the central wall 3 and maintain smooth water flow. In addition, by reserving a cast-in-place connection area 5 between adjacent cover plates 4, the pre-embedded steel reinforcement components 42 embedded in the cover plate 4 can be welded and connected in this area, and combined with subsequent cast-in-place concrete, an integrated continuous structure is formed. This not only transforms the originally relatively independent simply supported structure into a continuous structure that shares the load, but also effectively avoids the problem of reflective cracking caused by the deformation of the simply supported structure at the top of the central wall 3, thereby improving the overall structural performance of the road surface, ensuring road driving safety and comfort, and extending the service life of the road surface.

[0035] Specifically, the upper surface of the cover plate 4 is flush with the upper surface of the concrete, so that the cover plate 4 and the surface of the cast-in-place concrete form a continuous and uniform top surface, avoiding unevenness, which is conducive to the overall stress and deformation coordination of the structure, and can also reduce the risk of vehicle impact load or local cracking of concrete caused by height difference.

[0036] Optionally, micro-expansion concrete is used. Since micro-expansion concrete contains an appropriate amount of expansion components (such as calcium oxide, expansion agent, etc.), it produces a small volume expansion in the early stage of hardening, which can effectively compensate for the volume shrinkage of ordinary concrete caused by drying shrinkage, temperature difference, etc., and help reduce cracks caused by constraint. It is suitable for cast-in-place sections, continuous structure connection areas and other places that are prone to cracking.

[0037] In some alternative embodiments, a boss along the width direction of the base 1 is also provided at the bottom of the central wall 3. The boss is connected to the base 1 and can effectively increase the supporting force of the central wall 3.

[0038] In addition, the bottom of the protrusion 31 at the top of the central wall 3 is provided with reinforcing ribs, which can further enhance the supporting capacity of the protrusion 31 and make the structure of the central wall 3 more stable.

[0039] Furthermore, the circumferential joint between each positioning hole 43 and the positioning steel bar 32 can be sealed by grouting, which enhances the synergistic effect between the positioning steel bar 32 and the cover plate 4, avoids the risk of hollowing, cracking and water seepage caused by the circumferential joint, improves the overall compactness and impermeability of the structure, and ensures the durability of the structure; optionally, mortar can be injected into the circumferential joint for sealing, which is not specifically limited here.

[0040] In some embodiments, the top of the boss 31 is provided with a plurality of positioning steel bars 32 at intervals on both sides along the length direction of the base 1, and the lower surface of each cover plate body 41 is provided with a plurality of positioning holes 43, which can be inserted and cooperate with the plurality of positioning steel bars 32 on one side; wherein, by the cooperation between the positioning steel bars 32 provided on the boss 31 and the positioning holes 43 provided on the lower surface of the cover plate 4, the cover plate 4 can be temporarily positioned and initially fixed during the installation stage, providing a safe and convenient working basis for subsequent welding and concrete pouring processes.

[0041] Combination Figure 2 and Figure 3As shown, in order to increase the overall rigidity of the cover plate 4, the pre-embedded steel reinforcement assembly 42 includes an upper main steel reinforcement 421, an upper structural steel reinforcement 422, a lower main steel reinforcement 423, and a lower structural steel reinforcement 424. The upper main steel reinforcement 421 and the lower main steel reinforcement 423 are respectively positioned opposite each other on the upper and lower parts of the cover plate body 41 and are evenly spaced along the width direction of the base 1. Both can extend out of the cover plate body 41 along the width direction of the base 1. The upper main steel reinforcement 421 and the lower main steel reinforcement 423 positioned opposite each other on the adjacent cover plates 4 on each boss 31 are staggered. The upper structural steel reinforcement 422 is located between the upper main steel reinforcement 421 and the upper surface of the cover plate body 41, and the lower structural steel reinforcement 424 is located between the lower main steel reinforcement 423 and the lower surface of the cover plate body 41. Both are spaced apart along the length direction of the base 1. The upper main reinforcing bars 421 and the lower main reinforcing bars 423 are respectively arranged at the upper and lower edges of the cover plate body 41, forming an effective load-bearing lever arm, which can fully exert the bending resistance. The upper main reinforcing bars 421 and the lower main reinforcing bars 423 extend outward and can penetrate into the connection area of ​​adjacent cover plates 4, so that the original simply supported members can form a continuous beam structure after casting, improving the overall structure. In addition, the upper main reinforcing bars 421 and the lower main reinforcing bars 423 on each protrusion 31 are staggered in the cast-in-place connection area 5, which makes it easier to weld the joints and facilitates the formation of structural continuity by welding the reinforcing bars, thereby improving the connection strength. The upper structural reinforcing bars 422 and the lower structural reinforcing bars 424 are close to the surface of the cover plate body 41, which can control surface cracks caused by temperature difference, drying shrinkage, etc., and play a role in crack distribution control.

[0042] Furthermore, the upper main reinforcing bars 421, which are staggered between adjacent cover plates 4 on each boss 31, are welded together one by one along the width direction of the base 1, so that the cast-in-place connection area 5 forms a negative bending moment zone. Specifically, by welding the upper main reinforcing bars 421 together as a whole within the cast-in-place connection area 5 of the cover plates 4, the adjacent cover plates 4, which are originally simply supported, form a continuous beam in terms of structural behavior. The continuous connection of the upper main reinforcing bars 421 within the cast-in-place connection area 5 can form an effective negative bending moment zone under mid-span load, improving the bending stiffness and overall bearing capacity of the structure. At this time, the lower main reinforcing bars 423 can be welded in an intermittent, skip-welding manner, for example, connecting every other one. The specific number of intervals is not specifically limited here, thereby reducing construction difficulty, facilitating construction, and accelerating the construction progress.

[0043] Because the positioning hole 43 is opened on the lower surface of the cover plate 4, the surrounding area is weak, which will cause stress concentration. Especially under the stress of vehicle load, temperature difference or shrinkage, microcracks are more likely to form. Therefore, in order to solve the above problems, multiple upper structural steel bars 422 and multiple lower structural steel bars 424 are densely arranged near the positioning hole 43 on the cover plate body 41 to reinforce the opening position of the cover plate 4 and enhance the crack resistance of the opening part of the cover plate 4.

[0044] To enhance the connection strength of the cast-in-place connection area 5, in some embodiments, cast-in-place stirrups 51 and cast-in-place structural reinforcement 52 are provided within the cast-in-place connection area 5. The cast-in-place stirrups 51 are arranged vertically around the upper main reinforcement 421 and the lower main reinforcement 423 to form a closed stirrup frame. Multiple cast-in-place structural reinforcement 52 are arranged along the length of the base 1. The arrangement of the cast-in-place stirrups 51 around the upper main reinforcement 421 and the lower reinforcement helps to laterally restrain the concrete and prevent shear failure or diagonal cracks caused by shear force, negative bending moment or load concentration. Furthermore, the cast-in-place connection area 5 is a negative bending moment concentration area of ​​the bridge deck (such as the pier top), where the upper main reinforcement 421 bears tensile force and the structure is prone to cracking. The closed stirrups can limit the lateral displacement of the upper main reinforcement 421, prevent its buckling, improve the stiffness and ductility of the negative bending moment area, and delay failure. The arrangement of the cast-in-place structural reinforcement 52 along the length of the base 1 helps to share the secondary stresses such as early temperature shrinkage and drying shrinkage.

[0045] In some embodiments, the upper surface of each boss 31 is provided as a rough surface; and / or both end faces of each cover plate body 41 are provided as rough surfaces, so that the concrete is more tightly connected to the boss 31 and / or the cover plate body 41.

[0046] The culvert structure is exposed to water flow for a long time. Water can seep in through the gaps between the cover plate 4 and the side wall 2 and the middle wall 3, which may corrode the internal concrete or steel bars and induce problems such as corrosion, carbonization, and freeze-thaw damage. To solve the above problems, a waterproof layer is placed between the positioning groove 21 of the cover plate 4 and the side wall 2; and / or a waterproof layer is placed between the cover plate 4 and the protrusion 31 of the middle wall 3. The waterproof layer can effectively block the seepage path, reduce the risk of moisture inside the structure, and improve the overall service life.

[0047] Optionally, the waterproof layer may be, but is not limited to, asphalt felt, and the amount of asphalt felt can be laid according to the actual situation, without specific limitations.

[0048] In some embodiments, multiple cover plates 4 can be arranged side by side along the length of the base 1. Construction personnel can flexibly increase or decrease the number of cover plates 4 according to different bridge and culvert lengths or terrain conditions to adapt to various spans and traffic needs, thereby enhancing the versatility and adaptability of the structure.

[0049] The specific construction methods for multi-span bridges, including simply supported slab-continuous structures, are as follows:

[0050] S1: Prefabricate the base 1, side wall 2, middle wall 3 and cover plate 4 in advance, and transport all components to the construction site;

[0051] S2: Lay the base 1 on the foundation layer, and erect the two side walls 2 on both sides of the base 1 along the width direction of the base 1; at the same time, install the middle wall 3 between the two side walls 2 at a set interval, and arrange the middle wall 3 parallel to the side walls 2.

[0052] S3: Lay a waterproof layer in the positioning groove 21 at the top of the side wall 2 and on the top surface of the protrusion 31 of the middle wall 3;

[0053] S4: Align the positioning holes 43 on the lower surface of the cover plate 4 with the corresponding positioning steel bars 32 on the protrusion 31 of the middle wall 3 and insert them one by one. Place the cover plate 4 temporarily on the protrusion 31 of the middle wall 3 and the positioning groove 21 of the side wall 2 to complete the positioning.

[0054] S5: After all the cover plates 4 are in place, the upper main steel bars 421 arranged opposite to each other in each cast-in-place connection zone are welded together to form a negative bending moment zone.

[0055] S6: Within the cast-in-place connection area 5, lay and tie the cast-in-place structural steel bars 52 and the cast-in-place stirrups 51 to construct a closed load-bearing steel frame.

[0056] S7: Clean the top surface of the protrusion 31 of the central wall 3 and the impurities on both sides of the cover plate 4 in the cast-in-place connection area;

[0057] S8: Pour concrete in the cast-in-place connection area 5 and make its upper surface flush with the upper surface of the cover plate 4; after the pouring is completed, vibrate and compact the cast-in-place concrete and perform post-curing.

[0058] S9: Grouting is performed in the circumferential joint between the positioning hole 43 of the cover plate 4 and the positioning steel bar 32 to seal the joint.

[0059] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A multi-span bridge encompassing a slab-supported, variable-continuity structure, characterized in that: include: The base (1), two side walls (2), at least one middle wall (3), and multiple cover plates (4) are provided. The two side walls (2) are provided on the base (1) and are arranged opposite to each other along the length of the base (1). Each side wall (2) has a positioning groove (21) at its top for supporting the cover plate (4). The middle wall (3) is arranged between the side walls (2) and parallel to the side walls (2). Each middle wall (3) has a boss (31) at its top along the width of the base (1) for supporting the cover plate (4). Multiple cover plates (4) are respectively mounted across the positioning groove (21) of the side wall (2) and the boss (31) of the middle wall (3) along the width direction of the base (1); each cover plate (4) includes a cover plate body (41) and a pre-embedded steel reinforcement assembly (42), the pre-embedded steel reinforcement assembly (42) is located inside the cover plate body (41), and partially extends out of both sides of the cover plate body (41) along the width direction of the base (1); a cast-in-place connection area (5) is reserved between the top of the boss (31) and the cover plate (4), the pre-embedded steel reinforcement assemblies (42) of the adjacent cover plates (4) are welded together in the cast-in-place connection area (5), and can form an integral continuous structure by pouring concrete.

2. The multi-span bridge covering a simply supported to continuously spanned structure according to claim 1, characterized in that, The top of the boss (31) is provided with multiple positioning steel bars (32) spaced apart on both sides along the length direction of the base (1). Each cover plate body (41) has multiple positioning holes (43) on its lower surface, which can be inserted and engaged with multiple positioning steel bars (32) on one side.

3. The multi-span bridge covering a simply supported, variable-continuity structure according to claim 2, characterized in that, The circumferential joint between each of the positioning holes (43) and the positioning reinforcing bars (32) can be sealed by grouting.

4. The multi-span bridge covering a simply supported, variable-continuity structure according to claim 2, characterized in that, The pre-embedded steel reinforcement assembly (42) includes an upper main steel reinforcement (421), an upper structural steel reinforcement (422), a lower main steel reinforcement (423), and a lower structural steel reinforcement (424). The upper main steel reinforcement (421) and the lower main steel reinforcement (423) are respectively positioned opposite each other on the upper and lower parts of the cover plate body (41) and are evenly spaced along the width direction of the base (1). They can all extend out of the cover plate body (41) along the width direction of the base (1). The upper main steel reinforcement (421) and the lower main steel reinforcement (423) positioned opposite each other on the adjacent cover plates (4) on each boss (31) are staggered. The upper structural steel bar (422) is located between the upper main steel bar (421) and the upper surface of the cover plate body (41), and the lower structural steel bar (424) is located between the lower main steel bar (423) and the lower surface of the cover plate body (41), and both are arranged at intervals along the length direction of the base (1).

5. The multi-span bridge covering a simply supported, variable-continuity structure according to claim 4, characterized in that, The upper main steel bars (421) arranged alternately between adjacent cover plates (4) on each of the bosses (31) are welded together one by one along the width direction of the base (1) so that the cast-in-place connection area (5) forms a negative bending moment zone.

6. The multi-span bridge covering a simply supported, variable-continuity structure according to claim 5, characterized in that, The cover plate body (41) is densely arranged with multiple upper structural steel bars (422) and multiple lower structural steel bars (424) near the positioning hole (43).

7. The multi-span bridge covering a simply supported, variable-continuity structure according to claim 6, characterized in that, The cast-in-place connection area (5) is provided with cast-in-place stirrups (51) and cast-in-place structural steel bars (52). The cast-in-place stirrups (51) are arranged vertically around the upper main steel bar (421) and the lower main steel bar (423) to form a closed stirrup frame. Multiple cast-in-place structural steel bars (52) are arranged along the length of the base (1).

8. The multi-span bridge covering a simply supported variable continuous structure according to any one of claims 1-7, characterized in that, The upper surface of each of the bosses (31) is set as a rough surface; and / or Both ends of each of the cover plate bodies (41) are provided with the rough surface.

9. The multi-span bridge covering a simply supported variable continuous structure according to any one of claims 1-7, characterized in that, A waterproof layer is placed between the cover plate (4) and the positioning groove (21) of the side wall (2); and / or The waterproof layer is placed between the cover plate (4) and the boss (31) of the middle wall (3).

10. The multi-span bridge covering a simply supported variable continuous structure according to any one of claims 1-7, characterized in that, Multiple cover plates (4) can be arranged side by side along the length of the base (1).

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