New and old bridge widening structure for large height difference

Abstract

The utility model discloses a widening structure for new and old bridges with large height difference, which relates to the field of widening transformation of old bridges and comprises a first bridge body and a second bridge body. The first bridge body embedded steel bars and the second bridge body embedded steel bars are embedded in the tops of the first bridge body and the second bridge body respectively; the first bridge floor cast-in-place layer and the second bridge floor cast-in-place layer are both poured at the top ends of the first bridge body and the second bridge body; the anchoring steel bars are embedded in the top of the second bridge body and located at the bottoms of the second bridge body embedded steel bars, the lightweight concrete precast blocks are arranged at the top end of the second bridge body, and the outer sides of the lightweight concrete precast blocks are matched with the second bridge body embedded steel bars and the anchoring steel bars correspondingly. The lightweight concrete leveling layer is reasonable and reliable in structure, the lightweight concrete precast blocks are adopted to replace a traditional concrete leveling layer, the weight is reduced by 30%-50%, the dead load of the newly-added leveling layer is controlled within 15% of the live load of an original bridge, and the influence on the original bridge structure is remarkably reduced.

Description

Technical Field

[0001] This utility model relates to the field of widening and renovating old bridges, specifically to a widening structure for old and new bridges with significant elevation differences. Background Technology

[0002] With the continuous growth of urban traffic volume, widening and upgrading existing bridges has become an important technical means to improve the traffic capacity of the road network. However, in the practice of widening old and new bridges, due to factors such as construction errors, differences in foundation settlement, or bridge structural creep, a significant height difference (usually 5-15cm) often occurs at the widening joint between the old and new bridge decks. This bridge deck misalignment not only affects the ride comfort and drainage performance of the bridge deck, but also easily leads to concentrated vehicle impact loads, accelerating the damage to the bridge deck pavement layer, and in severe cases, may even threaten the safety of the bridge structure.

[0003] Traditional solutions typically use a cast-in-place concrete leveling layer to compensate for height differences, but this method has significant technical drawbacks: 1) Conventional concrete has a high density (24kN / m³), and thickening the leveling layer will significantly increase the dead load, causing the bending moment and shear force of the original bridge structure (especially lightweight superstructures such as hollow slabs and T-beams) to exceed the limits, requiring additional reinforcement, which is not economical; 2) When the thickness of the cast-in-place layer is too large, surface cracking is prone to occur due to the shrinkage and creep effect of concrete, and thick wet joints require long-term sealed curing (7-14 days), which seriously affects traffic access; 3) The interface between the new and old concrete relies only on conventional roughening treatment, and the interface shear strength is insufficient (<2MPa), making it prone to interlayer delamination failure under repeated vehicle loads.

[0004] No effective solutions have yet been proposed to address the problems in the relevant technologies. Utility Model Content

[0005] In view of the problems in the related technologies, this utility model proposes a widening structure for new and old bridges with large elevation differences, so as to overcome the above-mentioned technical problems existing in the existing related technologies.

[0006] Therefore, the specific technical solution adopted by this utility model is as follows:

[0007] A widening structure for bridges with significant elevation differences includes a first bridge body and a second bridge body; several pre-embedded reinforcing bars in the first bridge body and several pre-embedded reinforcing bars in the second bridge body, respectively embedded in the top of the first and second bridge bodies; a first and second cast-in-place bridge deck layers, both cast at the top of the first and second bridge bodies; several anchoring reinforcing bars, pre-embedded in the top of the second bridge body and located at the bottom of the pre-embedded reinforcing bars in the second bridge body; and several lightweight precast concrete blocks, placed at the top of the second bridge body, with the outer sides of the lightweight precast concrete blocks respectively cooperating with the pre-embedded reinforcing bars and anchoring reinforcing bars in the second bridge body.

[0008] Furthermore, in order to prevent the bridge from cracking or being damaged due to stress or uneven settlement, a bridge pre-reserved gap is provided between the first bridge body and the second bridge body; the bridge deck of the first bridge body is higher than the bridge deck of the second bridge body, and the difference in bridge deck between the first bridge body and the second bridge body is equal to the thickness of the lightweight precast concrete block.

[0009] Furthermore, in order to improve the connection reliability between the old and new structural layers and significantly enhance the structural safety, durability and driving comfort after the bridge widening and reconstruction, the bottom of the lightweight concrete precast block is provided with a groove to increase the contact area between the lightweight concrete precast block and the second bridge deck cast-in-place layer; after the lightweight concrete precast block and the groove are poured, a shear key is formed to improve the tensile strength of the interface and resist vehicle fatigue.

[0010] Furthermore, in order to improve the tensile strength of the interface, several shear keys are set with a sawtooth interface after casting.

[0011] Furthermore, in order to prevent crack development or structural separation caused by uneven stress and to significantly improve the integrity and durability of the widened structure, the embedded steel bars of the first bridge body and the embedded steel bars of the second bridge body are both set in an L-shaped or channel-shaped structure.

[0012] Furthermore, in order to form a more uniform stress transmission path and prevent cracking or peeling caused by local stress concentration, the anchoring steel bars are set in an L-shaped structure, and the ends are parallel to the pre-embedded positions of the second bridge body's pre-embedded steel bars.

[0013] Furthermore, to avoid structural cracking or slippage caused by weak connections, the pre-embedded steel bars and anchoring steel bars of the second bridge body are connected by welding.

[0014] Furthermore, in order to effectively improve the shear, tensile and fatigue resistance of the widened bridge deck and significantly enhance the safety and durability of the structure, the embedded steel bars of the first bridge body and the embedded steel bars of the second bridge body are arranged at equal intervals along the length of the lightweight precast concrete blocks.

[0015] The beneficial effects of this utility model are as follows:

[0016] 1. This utility model has a reasonable and reliable structure and is simple to operate. It uses lightweight precast concrete blocks to replace the traditional concrete leveling layer, reducing weight by 30%-50%. This allows the dead load of the newly added leveling layer to be controlled within 15% of the original bridge's live load, significantly reducing the impact on the original bridge structure and avoiding insufficient structural bearing capacity due to sudden load increases. This ensures the safety and stability of the overall bridge structure after widening and reconstruction. The lightweight precast concrete blocks, combined with the groove structure, increase the epoxy mortar bonding area by more than 40%, achieving an interface shear strength of 3.5 MPa. The key teeth on the top surface form a mechanical interlock with the second bridge deck cast-in-place layer, achieving a tensile strength of 8 MPa, significantly enhancing fatigue resistance and extending service life.

[0017] 2. This utility model uses lightweight precast concrete blocks, which are prefabricated in the factory with an accuracy of ±1mm. The blocks are then modularly hoisted and installed on site (each block weighs ≤400kg). Combined with steam curing (the blocks reach 90% of the design strength in 12 hours), the construction cycle is greatly shortened, traffic closure time is reduced, and construction efficiency and organizational flexibility are improved.

[0018] 3. By setting a second cast-in-place layer for the bridge deck, the thickness of the second cast-in-place layer can be controlled within 5cm. It has ultra-high bending toughness (≥30kJ / m²) and low shrinkage rate (≤200με), which completely avoids the cracking problem of traditional thick concrete layers and ensures that the bridge deck is flat and durable. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The following is a schematic diagram of a structure for widening old and new bridges with a large elevation difference;

[0021] Figure 2 The following is a schematic cross-sectional view of a structure used for widening old and new bridges with a large elevation difference, as described in the embodiments below.

[0022] Figure 3 The following is a schematic diagram of a structural plan of a bridge widening structure for bridges with significant elevation differences;

[0023] Figure 4 The following is a schematic diagram of the structure of the lightweight precast concrete block in the embodiments.

[0024] In the picture:

[0025] 1. First bridge body; 2. Second bridge body; 3. First bridge deck cast-in-place layer; 4. Embedded steel bars in the first bridge body; 5. Bridge reserved gap; 6. Lightweight precast concrete block; 7. Embedded steel bars in the second bridge body; 8. Second bridge deck cast-in-place layer; 9. Anchor steel bars; 10. Shear key; 11. Groove. Detailed Implementation

[0026] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0027] According to an embodiment of the present invention, a widening structure for new and old bridges with large elevation differences is provided.

[0028] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figures 1-4 As shown, a bridge widening structure for bridges with significant elevation differences, according to an embodiment of the present invention, includes a first bridge body 1 and a second bridge body 2; a plurality of pre-embedded reinforcing bars 4 in the first bridge body and a plurality of pre-embedded reinforcing bars 7 in the second bridge body, respectively pre-embedded in the top of the first bridge body 1 and the second bridge body 2; a first cast-in-place bridge deck layer 3 and a second cast-in-place bridge deck layer 8, both cast at the top of the first bridge body 1 and the second bridge body 2; a plurality of anchoring reinforcing bars 9, pre-embedded in the top of the second bridge body 2 and located at the bottom of the pre-embedded reinforcing bars 7 in the second bridge body; and a plurality of lightweight precast concrete blocks 6, disposed at the top of the second bridge body 2, with the outer sides of the lightweight precast concrete blocks 6 respectively cooperating with the pre-embedded reinforcing bars 7 and the anchoring reinforcing bars 9 in the second bridge body.

[0029] By utilizing the aforementioned technical solution of this utility model, lightweight precast concrete blocks 6 are used to replace the traditional concrete leveling layer, reducing weight by 30%-50%. This allows the dead load of the newly added leveling layer to be controlled within 15% of the original bridge's live load, significantly reducing the impact on the original bridge structure and avoiding the problem of insufficient structural bearing capacity due to sudden load increases. This ensures the safety and stability of the overall bridge structure after the widening and reconstruction. The lightweight precast concrete blocks 6, combined with the groove structure 11, increase the epoxy mortar bonding area by more than 40%, achieving an interface shear strength of 3.5 MPa. The key teeth on the top surface form a mechanical interlock with the second bridge deck cast-in-place layer 8, achieving a tensile strength of 8 MPa, significantly enhancing fatigue resistance and extending service life.

[0030] It needs to be explained that: the first bridge body 1 is the old bridge body, the second bridge body 2 is the new bridge body, the first bridge deck cast-in-place layer 3 is the old bridge deck cast-in-place layer, the first bridge body embedded steel bar 4 is the old bridge body embedded steel bar, the bridge reserved gap 5 is the reserved gap between the old and new bridges, the second bridge body embedded steel bar 7 is the new bridge body embedded steel bar, and the second bridge deck cast-in-place layer 8 is the new bridge UHPC cast-in-place layer.

[0031] In one embodiment, a bridge pre-reserved gap 5 is provided between the first bridge body 1 and the second bridge body 2; the bridge deck of the first bridge body 1 is higher than the bridge deck of the second bridge body 2, and the difference in bridge deck between the first bridge body 1 and the second bridge body 2 is equal to the thickness of the lightweight precast concrete block 6. This prevents the bridge from cracking or being damaged due to stress or uneven settlement.

[0032] In one embodiment, for the second bridge body 2, the bottom of the lightweight precast concrete block 6 is provided with a groove 11 to increase the contact area between the lightweight precast concrete block 6 and the second bridge deck cast-in-place layer 8; after the lightweight precast concrete block 6 and the groove 11 are poured, a shear key 10 is formed to improve the tensile strength of the interface and resist vehicle fatigue. This not only effectively improves the connection reliability between the old and new structural layers, but also significantly improves the structural safety, durability, and driving comfort after the bridge widening and reconstruction.

[0033] In one embodiment, for the shear keys 10, the plurality of shear keys 10 are arranged in a sawtooth-shaped interface after casting. This improves the tensile strength of the interface.

[0034] In one embodiment, both the first bridge body embedded steel bar 4 and the second bridge body embedded steel bar 7 are arranged in an L-shaped or channel-shaped structure. This prevents crack development or structural separation caused by uneven stress, significantly improving the integrity and durability of the widened structure.

[0035] In one embodiment, the anchoring steel bar 9 is arranged in an L-shape, with its ends parallel to the pre-embedded positions of the second bridge body's pre-embedded steel bar 7. This creates a more uniform stress transmission path, preventing cracking or peeling caused by localized stress concentration.

[0036] In one embodiment, the second bridge body embedded steel bar 7 is connected to the anchoring steel bar 9 by welding. This avoids structural cracking or slippage caused by weak connections.

[0037] In one embodiment, both the first bridge body embedded steel bar 4 and the second bridge body embedded steel bar 7 are arranged at equal intervals along the length of the lightweight precast concrete block 6. This effectively improves the shear, tensile, and fatigue resistance of the widened bridge deck, significantly enhancing the safety and durability of the structure.

[0038] It needs to be explained that the lightweight precast concrete block 6 is made of lightweight aggregate concrete (density ≤16kN / m³); the second bridge deck cast-in-place layer 8 is made of ultra-high performance concrete (UHPC) and continuously cast to cover the top surface of the precast blocks and the old and new bridge decks, with anti-crack steel wire mesh inside; the interface connection system includes the bottom surface of the lightweight precast concrete block 6 being bonded to the new bridge body with epoxy mortar, and the top surface and the surrounding area being integrated with the bridge beam through the UHPC cast-in-place layer.

[0039] To facilitate understanding of the above-mentioned technical solutions of this utility model, the working principle or operation method of this utility model in actual process will be described in detail below.

[0040] like Figures 1-4 As shown, in practical application, firstly, the workers mill the first bridge body 1 (i.e., the old bridge deck), removing the original pavement layer down to the structural layer and restoring the structural reference surface; then, precise measurement and layout are carried out to determine the installation elevation of the lightweight precast concrete blocks 6. Epoxy mortar is evenly applied to the old bridge deck at the predetermined installation location, and the lightweight precast concrete blocks 6 are precisely installed in place according to the design requirements. The groove 11 is used to ensure that the mortar is fully filled, improving the bonding performance and interface connection strength. After the precast blocks are installed, lateral anchoring steel bars 9 are inserted and the ultra-high performance concrete (UHPC) layer wire mesh is tied to enhance the overall structural integrity and lateral stability.

[0041] Finally, the second bridge deck cast-in-place layer 8 (UHPC) was constructed using a layered casting process. Because the top surface of the lightweight precast concrete block 6 has an array of rectangular grooves 11, these grooves are filled and hardened after the second bridge deck cast-in-place layer 8 (UHPC) is poured, forming a serrated mechanical interlocking interface that constitutes a shear bond. This significantly improves the shear strength and contact area between the second bridge deck cast-in-place layer 8 (UHPC) and the lightweight precast concrete block 6, achieving a reliable connection between the old and new structures.

[0042] This utility model is particularly applicable to the widening and reconstruction projects of light bridges such as prefabricated beam bridges and hollow slab bridges with a width-to-height difference of 5-15cm. It has significant technical and economic advantages and broad prospects for promotion and application.

[0043] In summary, by employing the above-mentioned technical solution of this utility model, and replacing the traditional concrete leveling layer with lightweight precast concrete blocks 6, the weight is reduced by 30%-50%, ensuring that the dead load of the newly added leveling layer is controlled within 15% of the original bridge's live load. This significantly reduces the impact on the original bridge structure, avoids the problem of insufficient structural bearing capacity due to sudden load increases, and ensures the safety and stability of the overall bridge structure after widening and reconstruction. The lightweight precast concrete blocks 6, combined with the groove structure 11, increase the epoxy mortar bonding area by more than 40%, achieving an interface shear strength of 3.5 MPa. The key teeth on the top surface form a mechanical interlock with the second bridge deck cast-in-place layer 8, achieving a tensile strength of 8 MPa, significantly enhancing fatigue resistance and extending service life. This invention utilizes lightweight precast concrete blocks 6, which are prefabricated in a factory with a precision of ±1mm. These blocks are then modularly hoisted and installed on-site (each block weighing ≤400kg), and combined with steam curing (achieving 90% of the design strength in 12 hours). This significantly shortens the construction cycle, reduces traffic closure time, and improves construction efficiency and organizational flexibility. Furthermore, this invention incorporates a second cast-in-place bridge deck layer 8, whose thickness can be controlled to within 5cm. This second layer possesses ultra-high flexural toughness (≥30kJ / m²) and low shrinkage (≤200με), completely avoiding the cracking problems of traditional thick concrete layers and ensuring a smooth and durable bridge deck.

[0044] In this utility model, unless otherwise explicitly specified and limited, the terms "installation", "setting", "connection", "fixing", "screw connection", etc., 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 connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0045] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A new and old bridge widening structure for large height difference, characterized in that, include: First bridge body (1) and second bridge body (2); Several first bridge body pre-embedded steel bars (4) and several second bridge body pre-embedded steel bars (7) are respectively pre-embedded in the top of the first bridge body (1) and the second bridge body (2); The first bridge deck cast-in-place layer (3) and the second bridge deck cast-in-place layer (8) are both cast on the top of the first bridge body (1) and the second bridge body (2); Several anchoring steel bars (9) are pre-embedded at the top of the second bridge body (2) and at the bottom of the pre-embedded steel bars (7) of the second bridge body; Several lightweight precast concrete blocks (6) are placed at the top of the second bridge body (2), and the outer side of the lightweight precast concrete blocks (6) is respectively matched with the embedded steel bars (7) of the second bridge body and the anchoring steel bars (9).

2. The new and old bridge widening structure for large height difference according to claim 1, characterized in that, A bridge reserved gap (5) is provided between the first bridge body (1) and the second bridge body (2); The bridge deck of the first bridge body (1) is higher than the bridge deck of the second bridge body (2), and the difference in bridge deck between the first bridge body (1) and the second bridge body (2) is equal to the thickness of the lightweight precast concrete block (6).

3. The new and old bridge widening structure for large height difference according to claim 1, characterized in that, The bottom of the lightweight precast concrete block (6) is provided with a groove (11) to increase the contact area between the lightweight precast concrete block (6) and the second bridge deck cast-in-place layer (8). After the lightweight precast concrete block (6) and the groove (11) are poured, a shear key (10) is formed to improve the tensile strength of the interface and resist vehicle fatigue.

4. The new and old bridge widening structure for large height difference according to claim 3, characterized in that, After the shear keys (10) are cast, they are set with a sawtooth-shaped interface.

5. The new and old bridge widening structure for large height difference according to claim 1, characterized in that, The first bridge body embedded steel bar (4) and the second bridge body embedded steel bar (7) are both set in an L-shaped or channel-shaped structure.

6. A bridge widening structure for bridges with significant elevation differences according to claim 1, characterized in that, The anchoring steel bar (9) is set in an L-shaped structure, and its end is parallel to the pre-embedded position of the second bridge body pre-embedded steel bar (7).

7. The new and old bridge widening structure for large height difference according to claim 1, characterized in that, The second bridge body pre-embedded steel bar (7) and the anchoring steel bar (9) are connected by welding.

8. The new and old bridge widening structure for large height difference according to claim 1, characterized in that, The first bridge body embedded steel bar (4) and the second bridge body embedded steel bar (7) are both arranged at equal intervals along the length direction of the lightweight concrete precast block (6).

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