A prefabricated connection structure for widening bridge decks without disrupting traffic and its design method

Abstract

This invention discloses a prefabricated connection structure and design method for widening bridge decks without disrupting traffic, belonging to the field of road and bridge engineering technology. Addressing the problems of significant interference from vehicle-bridge vibrations at wet joints between new and old bridges, long concrete curing cycles at connection points, susceptibility to cracking due to vibration, settlement, and other factors, and unstable construction quality, this invention proposes the use of prefabricated reinforced concrete connection plates. The connection between the new and old bridge decks is achieved through welding of connectors. Furthermore, the prefabricated plates can be prefabricated in a prefabrication yard, saving time and improving quality. The welding of connectors allows for fast on-site operations with minimal traffic disruption.

Description

Technical Field

[0001] This invention belongs to the field of road and bridge engineering technology, specifically relating to a prefabricated connection structure for widening bridge decks without interrupting traffic and its design method. Background Technology

[0002] With economic development and increased transportation volume, the number of lanes on highways in many places has become insufficient. To alleviate traffic pressure and improve bridge capacity, bridge widening has become an effective solution. However, widening existing bridges to connect old and new ones often involves closing the old bridge to traffic, causing significant disruption to normal traffic flow. There is an urgent need to develop innovative connection solutions to effectively address traffic disruptions, ensure construction safety, and minimize the impact on existing traffic order.

[0003] Currently, common bridge widening connections use wet joints. During construction, the coupled vibration of the vehicle-bridge system while maintaining uninterrupted traffic can affect the construction quality of the wet joint concrete. Furthermore, uneven settlement between the old and new bridges later on can lead to deformation or cracking at the connection point. A significant challenge in implementing uninterrupted traffic connection during bridge widening is ensuring the coordinated operation and deformation of the old and new bridge decks through appropriate connection and auxiliary support technologies, while minimizing interference from vehicle-bridge coupled vibrations and guaranteeing the construction quality of the connection. Existing research on uninterrupted traffic widening bridges exists, such as patent CN107100092A, which proposes a rapid bridge widening structure and installation method that allows for uninterrupted traffic. This method uses brackets to support the outer main beam, extending the flange plates to widen the bridge deck. It also proposes auxiliary structures such as diagonal braces and crossbeams, but only mentions the installation of longitudinal beams and bridge decks, without detailing the bridge deck construction. Its core purpose is to reduce the substructure of the new bridge for widening narrower bridge decks. Patent CN109371830A proposes a vibration damping device for bridge widening construction. This device uses a structural assembly to compress the new and old bridges, allowing them to share the load and reducing the deflection difference between them. Its core function is to minimize this difference. Patent CN223317102U proposes a corrugated plate splicing structure for bridge widening. This structure uses corrugated plates to connect the new and old bridges. The corrugated plates are located between the old bridge and the new steel-concrete composite beam bridge, and asphalt concrete is filled on top of the corrugated plates. The asphalt concrete and the corrugated plates jointly bear the settlement difference and additional internal forces between the new and old bridges. This patented connection structure has good deformation adaptability. However, the patent does not specify whether the corrugated steel plate, as the bottom formwork, forms a unified structure with the asphalt concrete—whether it is an integral part of the bridge deck and pavement or a separate pavement—and its thickness is unclear. Furthermore, its bending performance needs further improvement. Current research on widening bridges without disrupting traffic addresses issues such as the significant interference from vehicle-bridge vibrations at wet joints between new and old bridges, the long curing period for concrete at joints, and the susceptibility to cracking due to vibrations, settlement, and other factors, as well as unstable construction quality. Summary of the Invention

[0004] This invention provides a prefabricated connection structure and design method for widening bridge decks without interrupting traffic. It adopts prefabricated reinforced concrete connection plates and achieves the connection between the old and new bridge decks through welding of connectors.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A bridge deck widening prefabricated connection structure that does not interrupt traffic includes multiple prefabricated slabs arranged longitudinally and connected; the two transverse sides of the prefabricated slabs are respectively connected to the new and old bridge decks.

[0007] The planar dimensions of the precast slab can be 2m to 5m in length and 0.2m to 1m in width.

[0008] The precast slabs in the transverse direction need to ensure effective connection for transmitting vertical loads. Therefore, multiple sets of transverse connectors are evenly arranged along the longitudinal direction, using straight U-shaped steel bars, which can also serve as lifting points. It is preferable to set one set every 50cm. In the longitudinal direction, it is mainly necessary to consider the need to adapt to deformation. Therefore, the connectors need to have a certain elastic deformation capacity. By connecting with bent U-shaped steel bars, only 2 sets of connections can be set in the transverse direction, and the width of the perimeter joint can be reserved by 1cm.

[0009] The precast slab conforms to the stress characteristics of a one-way slab and adopts the double-layer reinforcement of a general bridge deck; the thickness and reinforcement of the precast slab can be consistent with the thickness and reinforcement of the new bridge deck.

[0010] Expansion bolts are driven into the old bridge deck where connections are needed, and steel plates are anchored therefor to connect with the transverse connectors on one side of the precast slab. Steel plates are pre-embedded in the new bridge deck and welded to the reinforcing bars within the slab, for connection with the transverse connectors on the other side of the precast slab. Finally, the transverse bridge deck structure is effectively connected by welding the transverse connectors on the precast slabs to the connecting steel plates of the new and old bridge decks. The longitudinal connectors of each precast slab segment are then welded to achieve effective longitudinal connection of the bridge. Finally, the joints are sealed, and the bridge deck pavement is poured uniformly.

[0011] The above-mentioned design method for prefabricated connection structures of bridge deck widening without disrupting traffic includes the following steps:

[0012] The precast slabs are designed taking into account the stress requirements of both the construction and use stages;

[0013] Design the connectors and ensure the diameter of the connecting steel bars meets the requirements: In the formula, d is the diameter of the connecting steel bar. Q0 represents the design value of the shear strength of the connecting reinforcement, and Q0 represents the shear force of a single connector.

[0014] The designed precast slabs and connectors are used to connect the new and old bridge decks. The transverse bridge deck structure is effectively connected by welding the transverse connectors on the precast slabs to the connecting steel plates of the new and old bridge decks. The longitudinal connectors of each segment of the precast slabs are welded to achieve the effective connection of the longitudinal bridge.

[0015] Beneficial Effects: This invention provides a prefabricated connection structure and design method for bridge widening without disrupting traffic. It considers the stress requirements of both construction and use stages when designing precast slabs and connectors. The lateral sides of the precast slabs are connected to the new and old bridge decks respectively, transforming the connection between the new and old bridge decks in bridge widening from a wet joint connection to a precast slab plus steel welded connection. Standardized construction of precast slabs improves the quality of concrete slab construction, reduces on-site curing time, is environmentally friendly, and is unaffected by weather factors. On-site connection construction only includes inserting steel plates and welding connections. Since the insertion and welding are not affected by traffic, there is no need to close the old bridge during operation, and the connection operation time is short, enabling rapid connection in bridge widening. This invention solves the problems of existing technologies, such as the large interference from vehicle and bridge vibrations in wet joint connections between new and old bridges, long concrete curing periods at the connection points, susceptibility to cracking due to vibration, settlement, and other factors, and unstable construction quality. Moreover, precast slabs can be prefabricated in a prefabrication yard, saving time and improving quality. Welding of connectors allows for fast on-site operation with minimal traffic interference. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall plan view of the bridge widening precast slab connection structure in an embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram showing the location of the precast slab lifting points in an embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of the connector and connecting steel plate in an embodiment of the present invention;

[0019] Figure 4 This is a structural diagram of the precast slab in an embodiment of the present invention;

[0020] Figure 5 This is a partial schematic diagram of the old bridge deck in an embodiment of the present invention;

[0021] In the diagram, 1-precast slab, 2-bent U-shaped steel bar, 3-straight U-shaped steel bar, 4-reinforcing bar (expansion bolt), 5-connecting steel plate. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments:

[0023] like Figure 1As shown, a prefabricated connection structure for widening bridge decks without interrupting traffic is presented, which can be used for "construction while traffic is open." It employs segmented prefabricated slabs longitudinally, with connectors around the perimeter of each slab. The design of the prefabricated slabs considers the stress requirements of both construction and use phases. During the construction phase, the first step is the selection of lifting point locations, such as... Figure 2 As shown, let the plate length be L and the distance from the lifting point to the end be x. When the positive and negative bending moments are balanced, the distance from the lifting point to the end is... .

[0024] During the construction phase, the precast slab bears its own weight. Considering the dynamic load effect during hoisting, and taking a dynamic coefficient of 1.5 as the most unfavorable effect, when the slab width is b and the slab thickness is h, the most unfavorable positive and negative bending moments are M0 = 0.9bhL. 2 The reinforcement in the slab can be calculated using formulas (1) and (2):

[0025] (1),

[0026] (2),

[0027] In the formula For safety, a factor of 1.0 to 1.1 is used; This is the design value for the axial compressive strength of the precast concrete slab; , These are the design values ​​for the tensile strength and compressive strength of the longitudinal reinforcing bars, respectively. , The cross-sectional area of ​​the longitudinal ordinary reinforcement in the tension and compression zones of the slab; h0 is the effective height of the section, h0 = h - a, where h is the total height of the section; a, It is the distance from the resultant point of the reinforcing bars in the tension zone and compression zone to the edge of the tension zone and compression zone, respectively.

[0028] During the service phase, the precast slabs primarily transmit forces in the transverse direction of the bridge. The ratio of the longitudinal to transverse side length of the precast slab is generally greater than 2, conforming to the stress characteristics of a one-way slab. Therefore, reinforcement is calculated based on transverse stress. The precast slabs are connected to the new and old bridge decks via welded steel bars. The connection strength is weaker than that of wet joints; therefore, the internal force calculation of the precast slabs uses a simply supported slab model, without the reduction for continuous one-way slabs. Clearly, the transverse span of the precast slabs is smaller than the spans of both the new and old bridge decks. Therefore, the thickness and reinforcement of the precast slabs can be conservatively taken to be consistent with the thickness and reinforcement of the new bridge deck.

[0029] Expansion bolts are driven into the old bridge deck where connections are needed and steel plates are anchored for connection with the transverse connectors on one side of the precast slab; steel plates are pre-embedded in the new bridge deck and welded to the steel bars inside the slab for connection with the transverse connectors on the other side of the precast slab; finally, the transverse bridge deck structure is effectively connected by welding the transverse connectors on the precast slab to the connecting steel plates of the new and old bridge decks; the longitudinal connectors of each segment of the precast slab are welded to achieve the effective connection of the longitudinal bridge. The connectors need to be verified. The main verification process is as follows: the shear force on the edge of the slab is calculated by the stress analysis of the bridge deck, which is the total shear force on the connector. Divide it by the number of connectors on one side to obtain the shear force Q0 of a single connector. Then calculate whether the diameter of the connecting steel bars meets the requirements according to formula (3):

[0030] ,

[0031] In the formula, d is the diameter of the connecting steel bar. This is the design value for the shear strength of the connecting reinforcement.

[0032] Finally, the joints were sealed, and the bridge deck paving was poured uniformly.

[0033] Example 1

[0034] like Figure 4 As shown, the precast slabs participate in the load-bearing as part of the bridge deck. They are longitudinally divided into multiple rectangular precast slabs 1. The planar dimensions of the precast slabs 1 can be 2m~5m in longitudinal length and 0.2m~1m in transverse width. The precast slabs 1 meet the load-bearing characteristics of one-way slabs. According to calculations, when using double-layer reinforcement of general bridge decks, it can meet the requirements for hoisting and operation. Therefore, the thickness and reinforcement of the precast slabs can be consistent with the thickness and reinforcement of the new bridge deck. Specifically, it can be designed and calculated according to the "Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts".

[0035] like Figure 3 As shown, the transverse direction of the precast slab 1 needs to ensure effective connection to transfer vertical loads. Therefore, a set of transverse connectors is set every 50cm along the longitudinal direction. The transverse connectors are straight U-shaped steel bars 3. The longitudinal direction of the bridge mainly needs to consider the need to adapt to deformation. Therefore, the connectors need to have a certain elastic deformation capacity. They are connected by bending U-shaped steel bars 2, and only two sets of connections are required. The width of the perimeter joint can be reserved by 1cm.

[0036] like Figure 5As shown, expansion bolts 4 are driven into the old bridge deck where connections are needed, and steel plates 5 are anchored for connection with the straight U-shaped steel bars 3 of the precast slab 1. Steel plates are pre-embedded in the new bridge deck and welded to the steel bars inside the slab for connection with the straight U-shaped steel bars 3 of the precast slab 1. The transverse bridge deck structure is effectively connected by welding the connectors on the precast slab 1 to the connecting steel plates of the new and old bridge decks. The bent U-shaped steel bars 2 of each segment of the precast slab 1 are welded to achieve the longitudinal bridge connection. After the precast slab 1 is hoisted into place, it is leveled, paying attention to alignment with the connecting steel plates 5. The setting of the connecting steel plates on the sides of the new and old bridge decks provides a large adjustable tolerance for alignment. After leveling, the position of the connecting plates is fixed by the under-bridge supports or the lifting rings on the bridge, and then the welding connection is quickly performed. Finally, the joints are sealed, and the bridge deck pavement is poured uniformly.

[0037] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A prefabricated connection structure for widening bridge decks without disrupting traffic, characterized in that, It includes multiple precast slabs arranged longitudinally and connected; the transverse sides of the precast slabs are respectively connected to the new and old bridge decks; the transverse bridge deck structure is connected by welding the transverse connectors on the precast slabs to the connecting steel plates of the new and old bridge decks; the longitudinal connectors of each segment of the precast slabs are welded to achieve effective connection of the longitudinal bridge.

2. The bridge deck widening prefabricated connection structure for uninterrupted traffic as described in claim 1, characterized in that, The precast slab has the following dimensions: longitudinal length 2m~5m, and transverse width 0.2m~1m.

3. The bridge deck widening prefabricated connection structure for uninterrupted traffic as described in claim 1, characterized in that, The transverse connectors are evenly arranged in multiple sets along the longitudinal direction, and the longitudinal connectors are evenly arranged along the transverse direction.

4. The bridge deck widening prefabricated connection structure for non-disruptive traffic widening according to claim 1 or 3, characterized in that, The transverse connector uses straight U-shaped steel bars; the longitudinal connector uses bent U-shaped steel bars.

5. The bridge deck widening prefabricated connection structure for uninterrupted traffic as described in claim 4, characterized in that, A 1cm margin can be reserved for the width of the surrounding seams.

6. The bridge deck widening prefabricated connection structure for non-disruptive traffic widening according to claim 1 or 2, characterized in that, The thickness and reinforcement of the precast slab are the same as those of the new bridge deck.

7. The bridge deck widening prefabricated connection structure for uninterrupted traffic as described in claim 1, characterized in that, Expansion bolts are driven into the bridge deck of the old bridge to anchor steel plates at the connection points, which are used to connect with the transverse connectors on one side of the precast slab; steel plates are pre-embedded in the bridge deck of the new bridge and welded to the steel bars inside the slab, which are used to connect with the transverse connectors on the other side of the precast slab.

8. The bridge deck widening prefabricated connection structure for uninterrupted traffic as described in claim 1, characterized in that, The longitudinal connectors of each precast slab are welded together to achieve the connection of the longitudinal bridge.

9. The design method for the prefabricated connection structure of a bridge widening deck that does not interrupt traffic, as described in any one of claims 1-8, is characterized in that... Includes the following steps: The precast slabs are designed taking into account the stress requirements of both the construction and use stages; Design the connectors and ensure the diameter of the connecting steel bars meets the requirements: In the formula, d is the diameter of the connecting steel bar. Q0 represents the design value of the shear strength of the connecting reinforcement, and Q0 represents the shear force of a single connector. The designed precast slabs and connectors are used to connect the new and old bridge decks. The transverse bridge deck structure is effectively connected by welding the transverse connectors on the precast slabs to the connecting steel plates of the new and old bridge decks. The longitudinal connectors of each segment of the precast slabs are welded to achieve the effective connection of the longitudinal bridge.

10. The design method for a prefabricated connection structure of a bridge deck widening that does not interrupt traffic, as described in claim 9, is characterized in that... During the construction phase, the precast slab bears its own weight. Considering the dynamic load effect during hoisting, and taking a dynamic coefficient of 1.5 as the most unfavorable effect, when the slab width is b and the slab thickness is h, the most unfavorable positive and negative bending moments are M0 = 0.9bhL. 2 Calculate the reinforcement in the slab using the following formula: ， ， In the formula For safety factor, take 1.0~1.1; x is the distance from the lifting point to the end when positive and negative bending moments are balanced; This is the design value for the axial compressive strength of the precast concrete slab; , These are the design values ​​for the tensile strength and compressive strength of the longitudinal reinforcing bars, respectively. , The cross-sectional area of ​​the longitudinal ordinary reinforcement in the tension and compression zones of the slab; h0 is the effective height of the section, h0 = h - a, where h is the total height of the section; a, It is the distance from the resultant point of the reinforcing bars in the tension zone and compression zone to the edge of the tension zone and compression zone, respectively.

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