Transition structure of a uHPC bridge deck slab and a steel-uHPC combined bridge deck slab

Abstract

This invention discloses a transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck, installed on a main girder. The main girder contains several spaced transverse diaphragms. The UHPC bridge deck includes a first UHPC layer, and the steel-UHPC composite bridge deck includes a steel plate and a second UHPC layer on the steel plate. The transition section includes a UHPC layer thickness gradient section for connecting the UHPC bridge deck and the steel-UHPC composite bridge deck. The UHPC layer thickness gradient section is located between two adjacent transverse diaphragms within the main girder. One end of the steel plate extends downwards from the UHPC bridge deck, forming an extension. The lower part of the steel plate is provided with longitudinal stiffening ribs and longitudinal transition stiffening ribs, which are connected in a cooperative manner. This invention can achieve a smooth transition of structural stiffness, avoid stress concentration, and improve structural performance.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, specifically to a transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck. Background Technology

[0002] Ultra-high performance concrete (UHPC) is increasingly widely used in modern bridge construction due to its superior mechanical properties and durability. In the design of UHPC composite beam bridge decks, two typical construction forms are usually adopted based on stress requirements and structural layout: one is to use UHPC bridge decks in conventional stress sections, which is simple in structure and convenient to construct; the other is to use steel-UHPC composite bridge decks in sections subjected to large negative bending moments or where self-weight reduction is required. This involves laying a UHPC layer on a steel base plate, utilizing the high tensile strength of steel to compensate for the insufficient tensile capacity of UHPC, while simultaneously reducing the self-weight of the bridge deck.

[0003] In actual bridge engineering, different sections of a bridge often require different bridge deck structures based on their stress characteristics. For example, steel-UHPC composite bridge decks are used in the negative bending moment zone at the supports of a continuous beam bridge to improve crack resistance, while UHPC bridge decks are used in the positive bending moment zone at mid-span to simplify the structure; or in long-span cable-stayed bridges, UHPC bridge decks are used in the side spans to increase counterweight, while steel-UHPC composite bridge decks are used in the mid-span to reduce self-weight.

[0004] However, UHPC bridge decks and steel-UHPC composite bridge decks differ significantly in structural design, stiffness distribution, and material composition. The former is a pure UHPC structure, while the latter is a steel-UHPC composite structure. At the connection point, problems such as abrupt stiffness changes, deformation inconsistencies, and stress concentration can easily occur. Traditional connection methods often employ simple direct butt joints, which are insufficient to meet the high strength, high durability, and fatigue resistance requirements of UHPC structures at the connection points. Therefore, there is an urgent need for a transition section structure specifically designed for UHPC bridge decks and steel-UHPC composite bridge decks to achieve a smooth transition and reliable connection between the two different structural forms of bridge decks. Summary of the Invention

[0005] This invention proposes a transition section structure between UHPC bridge deck and steel-UHPC composite bridge deck, which can overcome the problems of abrupt stiffness change and stress concentration at the connection between two different types of bridge decks in the prior art, and achieve a smooth transition of structural stiffness and effective force transfer, which has significant technical innovation.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck, disposed on a main beam, wherein the main beam contains a plurality of spaced transverse diaphragms; the UHPC bridge deck includes a first UHPC layer; the steel-UHPC composite bridge deck includes a steel plate and a second UHPC layer on the steel plate; the transition section is used to connect the first section of the UHPC bridge deck and the second section of the steel-UHPC composite bridge deck laid on the main beam, including the steel-UHPC composite bridge deck... The extension portion extends from the composite bridge deck to the bottom surface of the UHPC bridge deck, and the UHPC layer thickness gradient section connects the UHPC bridge deck and the steel-UHPC composite bridge deck. The UHPC layer thickness gradient section is located between two adjacent transverse diaphragms within the main beam. The extension portion includes an extended steel plate extending from the steel plate of the steel-UHPC composite bridge deck to the bottom surface of the UHPC bridge deck. The bottom surfaces of the steel plate and the extended steel plate are provided with longitudinal stiffening ribs and longitudinal transition stiffening ribs. The lower part of the longitudinal stiffening ribs is symmetrically welded to both sides of the longitudinal transition stiffening ribs.

[0007] The UHPC layer thickness gradient section is a UHPC layer connecting the first UHPC layer and the second UHPC layer. The UHPC layer thickness gradient section is located in the middle of the transition section, and its length is not less than 8 times the thickness difference between the first UHPC layer and the second UHPC layer at both ends.

[0008] The transverse spacing of the UHPC bridge deck reinforcement and the transverse reinforcement of the steel-UHPC composite bridge deck is a multiple of each other.

[0009] In the UHPC layer area of ​​equal thickness between the UHPC bridge deck and the steel-UHPC composite bridge deck, uniformly distributed shear studs are used. In the UHPC layer thickness gradient area, irregularly shaped slotted PBL shear connectors are used.

[0010] The longitudinal stiffener extends from the steel-UHPC composite bridge deck to one end of the UHPC layer thickness gradient section near the UHPC bridge deck, and is broken at the diaphragm closest to the thickness gradient section before being welded to the diaphragm. The longitudinal stiffener covers the thickness gradient section along the longitudinal length of the bridge.

[0011] The longitudinal transition stiffener adopts an inverted T-shaped structure, and the overlap length between the longitudinal stiffener and the longitudinal stiffener set at the bottom of the steel-UHPC composite bridge deck is not less than the distance between two adjacent transverse diaphragms. The overlapping longitudinal stiffener and the longitudinal transition stiffener are effectively welded to form an integral whole.

[0012] The transverse spacing of the transverse reinforcement bars in the UHPC layer of the UHPC bridge deck is one or two times that of the transverse reinforcement bars in the UHPC layer of the steel-UHPC composite bridge deck.

[0013] The anchorage length of the longitudinal reinforcement bars of the UHPC bridge deck and the steel-UHPC composite bridge deck embedded in each other within the UHPC layer reaches 30 times the diameter of the reinforcement bars.

[0014] Beneficial effects: By setting up a UHPC layer thickness gradient section and longitudinal transition stiffeners with varying heights, a smooth transition of structural stiffness is achieved, effectively avoiding stress concentration. The thickness of the UHPC layer within the transition section is not increased, and no steel grating is added within the UHPC layer. Through the extension of steel plates, the combined use of various shear connectors, and the differentiated design of reinforcing bars, reliable connections between structures and effective transmission of internal forces are ensured, improving structural performance while also taking into account the convenience and economy of construction. Attached Figure Description

[0015] Figure 1 This is a longitudinal cross-sectional schematic diagram of the transition section structure provided in an embodiment of this application; Figure 2 This is a schematic cross-sectional view of the transition section structure provided in an embodiment of this application; Figure 3 This is a schematic diagram of the arrangement of shear connectors for the transition section structure provided in the embodiments of this application; Figure 4 A schematic diagram of the slotted PBL shear connector for the transition section structure provided in this application embodiment; Figure 5 A schematic diagram of a steel grating cell and UHPC bridge deck with a conventional transition structure. Detailed Implementation

[0016] In the description of the embodiments of the present invention, it should be noted that the terms "upper," "lower," "left," "right," "top," "bottom," "vertical," "horizontal," "front end," "rear end," "diaphragm," "inner," and "outer," etc., indicate the orientation or positional relationship based on the normal use state of the bridge and the spatial relationship defined by the observer along the longitudinal direction of the bridge (i.e., along the bridge span direction). In the bridge structure, "upper" and "top" generally refer to the direction towards the sky, while "lower" and "bottom" refer to the direction towards the ground or water. When describing "left" and "right," it is assumed that the observer is standing on the bridge deck, facing... In the context of bridge design mileage increases, "left" refers to the observer's left-hand side, and "right" refers to the observer's right-hand side. "Front end" and "rear end" refer to the ends of the bridge structure along the longitudinal direction of the bridge. "Vertical" means parallel to the direction of gravity, and "horizontal" means perpendicular to the vertical direction. "Web plate" is the vertical load-bearing plate connecting the top and bottom plates in the bridge beam structure. "Diaphragm" refers to a component arranged transversely along the bridge, connecting the web plates of the left and right main beams or box girders. These terms indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and are therefore understood as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the invention according to the specific circumstances.

[0017] A transition section structure for a UHPC bridge deck and a steel-UHPC composite bridge deck is provided on a main girder 1 to connect a first section of UHPC bridge deck 2 and a second section of steel-UHPC composite bridge deck 3 laid on the main girder 1. The structure includes: an extension extending from the steel-UHPC composite bridge deck 3 to the bottom surface of the UHPC bridge deck 2; and a UHPC layer thickness gradient section 7 connecting the UHPC bridge deck 2 and the steel-UHPC composite bridge deck 3. The main girder 1 is a channel-shaped steel box girder, and several spaced transverse diaphragms 11 are provided within the main girder 1 along the longitudinal direction of the bridge. The UHPC bridge deck 2 includes a first UHPC layer 21, and the steel-UHPC composite bridge deck 3 includes a steel plate 31 and a second UHPC layer 32 laid on the steel plate 31. The extension includes an extension steel plate 35 extending from the steel plate 31 of the steel-UHPC composite bridge deck 3 to the bottom surface of the UHPC bridge deck 2. The bottom surfaces of the steel plate 31 and the extension steel plate 35 are provided with longitudinal stiffening ribs 33 and longitudinal transition stiffening ribs 4. The lower part of the longitudinal stiffening ribs 33 is symmetrically welded to both sides of the longitudinal transition stiffening ribs 4, and the upper part of the longitudinal stiffening ribs 33 is welded to the bottom surfaces of the steel plate 31 and the extension steel plate 35. The UHPC layer thickness gradient section 7 is a UHPC layer connecting the first UHPC layer 21 and the second UHPC layer 32. It is located in the middle of the transition section and between adjacent transverse diaphragms 11 inside the main beam.

[0018] Furthermore, the length of the UHPC layer thickness gradient section 7 is not less than 8 times the thickness difference between the first UHPC layer 21 and the second UHPC layer 32 at both ends. The thickness of the UHPC layer thickness gradient section 7 changes linearly, so as to achieve a smooth transition in stiffness between the UHPC layers of the UHPC bridge deck 2 and the steel-UHPC composite bridge deck 3. The UHPC layers of the UHPC bridge deck 2, the steel-UHPC composite bridge deck 3 and the UHPC layer thickness gradient section 7 between them are all cast in place in the factory.

[0019] Furthermore, the transverse reinforcement bars of UHPC bridge deck 2 and steel-UHPC composite bridge deck 3 in the UHPC layer adopt different specifications and transverse spacing according to the stress. The transverse spacing of the transverse reinforcement bars of UHPC bridge deck 2 in the UHPC layer is 1 or 2 times that of the transverse reinforcement bars of steel-UHPC composite bridge deck 3 in the UHPC layer, which can ensure that the reinforcement bars are arranged correspondingly or centrally interspersed.

[0020] The anchorage length of the longitudinal reinforcement 14 of the UHPC bridge deck 2 and the steel-UHPC composite bridge deck 3 embedded in each other within the UHPC layer reaches 30 times the diameter of the reinforcement. When the UHPC bridge deck 2 uses a single layer of longitudinal reinforcement within the UHPC layer, and the steel-UHPC composite bridge deck 3 uses a double layer of longitudinal reinforcement within the UHPC layer, the bottom reinforcement of the double layer of longitudinal reinforcement is cut off at the middle position of the variable thickness section.

[0021] Furthermore, shear connectors are installed on the contact surfaces of the steel plate 35 with the UHPC layer of the UHPC bridge deck 2 and the contact surfaces of the steel plate 35 with the UHPC layer of the steel-UHPC composite bridge deck 3. In the uniform thickness area of ​​the UHPC layer, the shear connectors use evenly distributed shear studs 5. The shear studs 5 can be selected according to different specifications based on the thickness of the UHPC layer and the stress. In the thickness transition section 7 of the UHPC layer, due to the dense reinforcement and large thickness variation, the shear connectors use irregularly shaped slotted PBL shear connectors 6, which are perforated steel plate shear connectors with irregularly shaped slots. They are installed between the steel plate and the UHPC concrete to transfer shear force, enhance interlocking, and ensure the coordinated work of the composite structure, so as to ensure the effective combination of the UHPC layer and the steel structure.

[0022] Furthermore, the longitudinal stiffening rib 33 extends from the steel-UHPC composite bridge deck 3 to one end of the UHPC layer thickness gradient section 7 near the UHPC bridge deck 2, and is broken at the diaphragm 11 closest to the thickness gradient section 7 before being welded to the diaphragm 11. The longitudinal stiffening rib 33 covers the UHPC layer thickness gradient section 7 along the longitudinal length of the bridge. The longitudinal transition stiffening rib 4 adopts an inverted T-shaped structure, and the overlap length with the longitudinal stiffening rib 33 set at the lower part of the steel-UHPC composite bridge deck 3 is not less than the distance between two adjacent diaphragms 11. The overlapping longitudinal stiffening rib 33 and the longitudinal transition stiffening rib 4 are effectively welded to form an integral whole.

[0023] Furthermore, the longitudinal transition stiffener 4, with its inverted T-shaped structure at the bottom of the UHPC bridge deck 2, overlaps with the longitudinal stiffener 33 set at the bottom of the steel-UHPC composite bridge deck 3 along the longitudinal direction of the bridge for a length not less than the distance between two adjacent transverse diaphragms. The longitudinal transition stiffener 4 then becomes an I-shaped structure and gradually decreases in height, and is cut off at an appropriate position to achieve a smooth transition in stiffness.

[0024] Furthermore, the transition section structure eliminates the need for, Figure 5 The structure features a conventional transition structure with steel grating 12 and locally thickened UHPC bridge deck sections 13. The bridge deck transition is completed between only one adjacent diaphragm 11, reducing the amount of UHPC by 55% and the structural weight by nearly 30%, ensuring that the weight of the beam segment including this transition section does not exceed that of the adjacent ordinary beam segment. In terms of stress, the elastic bending stiffness of this structure is uniformly distributed along the bridge length, and its cross-sectional elastic bending stiffness is only 1.06 times that of the UHPC bridge deck and 1.27 times that of the UHPC bridge deck.

[0025] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck, disposed on a main beam (1), wherein the main beam (1) contains a plurality of spaced transverse diaphragms (11), the UHPC bridge deck (2) includes a first UHPC layer (21), and the steel-UHPC composite bridge deck (3) includes a steel plate (31) and a second UHPC layer (32) on the steel plate (31), characterized in that, The transition section is used to connect the first section of the UHPC bridge deck (2) and the second section of the steel-UHPC composite bridge deck (3) laid on the main beam (1). It includes an extension extending from the steel-UHPC composite bridge deck (3) to the bottom surface of the UHPC bridge deck (2) and a UHPC layer thickness gradient section (7) connecting the UHPC bridge deck (2) and the steel-UHPC composite bridge deck (3). The UHPC layer thickness gradient section (7) is located between two adjacent transverse diaphragms (11) in the main beam (1). The extension includes an extension steel plate (35) extending from the steel plate (31) of the steel-UHPC composite bridge deck (3) to the bottom surface of the UHPC bridge deck (2). The bottom surfaces of the steel plate (31) and the extension steel plate (35) are provided with longitudinal stiffening ribs (33) and longitudinal transition stiffening ribs (4). The lower part of the longitudinal stiffening ribs (33) is symmetrically welded to both sides of the longitudinal transition stiffening ribs (4).

2. The transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck according to claim 1, characterized in that, The UHPC layer thickness gradient section (7) is a UHPC layer connecting the first UHPC layer (21) and the second UHPC layer (32). The UHPC layer thickness gradient section (7) is located in the middle of the transition section, and its length is not less than 8 times the thickness difference between the first UHPC layer (21) and the second UHPC layer (32) at the front and rear ends.

3. The transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck according to claim 1, characterized in that, The transverse spacing of the UHPC bridge deck (2) and the transverse spacing of the steel-UHPC composite bridge deck (3) are multiples of each other.

4. The transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck according to claim 1, characterized in that, In the UHPC layer area of ​​equal thickness between the UHPC bridge deck (2) and the steel-UHPC composite bridge deck (3), uniformly distributed shear studs (5) are used, and in the UHPC layer thickness gradient section (7) area, irregular groove type PBL shear connectors (6) are used.

5. The transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck according to claim 1, characterized in that, The longitudinal stiffener (33) extends from the steel-UHPC composite bridge deck (3) to one end of the UHPC layer thickness gradient section (7) near the UHPC bridge deck (2), and is welded to the diaphragm (11) at the point closest to the thickness gradient section (7). The longitudinal stiffener (33) covers the thickness gradient section (7) along the longitudinal length of the bridge.

6. The transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck according to claim 1, characterized in that, The longitudinal transition stiffener (4) adopts an inverted T-shaped structure, and the overlap length with the longitudinal stiffener (33) set at the bottom of the steel-UHPC composite bridge deck (3) is not less than the distance between two adjacent transverse diaphragms (11).

7. The transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck according to claim 1, characterized in that, The transverse spacing of the transverse reinforcement in the UHPC bridge deck (2) within the UHPC layer is 1 or 2 times that of the transverse reinforcement in the steel-UHPC composite bridge deck (3) within the UHPC layer.

8. The transition section structure between a UHPC bridge deck and a steel-UHPC composite bridge deck according to claim 1, characterized in that, The anchorage length of the longitudinal reinforcing bars (14) of the UHPC bridge deck (2) and the steel-UHPC composite bridge deck (3) embedded in each other within the UHPC layer reaches 30 times the diameter of the reinforcing bars.

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