Opposite-pulling assembly for improving crack resistance of joint interface between UHPC (Ultra High Performance Concrete) cast-in-place slabs

Abstract

The opposite-pull assembly for improving the crack resistance of the UHPC cast-in-place slab joint interface comprises side fixing plates arranged in a UHPC prefabricated bridge deck slab along the two sides of a joint and opposite-pull screws stretching across the joint to be detachably fixed to the side fixing plates in an opposite-pull mode, and the opposite-pull screws are distributed in the longitudinal direction of the joint at equal intervals. Opposite pressure stress is generated on the side fixing plates by adjusting the axial displacement of the opposite-pull screw rods, a plurality of local pressure bearing areas continuously distributed in the longitudinal direction of the joint are formed between the side fixing plates, and the opposite-pull screw rods comprise inner screw rods arranged in the UHPC prefabricated bridge deck slab and outer screw rods arranged on the lower end face of the UHPC prefabricated bridge deck slab; a pair of opposite pressure stress is generated on the rear end area of a side fixing plate steel plate located in the UHPC cast-in-place slab through the opposite-pull screws, and a plurality of local pressure bearing areas continuously distributed in the longitudinal direction are formed in a joint area, so that the interface of the core part of the area is subjected to the action of the core pressure, and the crack resistance of the joint interface of the UHPC cast-in-place slab is improved.

Description

Technical Field

[0001] The invention relates to a joint reinforcement component, in particular to a tensioning assembly for improving the crack resistance of a joint interface between UHPC cast-in-place slabs. Background Art

[0002] With the application and promotion of ultra-high performance concrete (UHPC) in bridges, prefabricated bridge panels and cast-in-place joints of prefabricated steel-concrete composite beams are increasingly adopting the form of UHPC cast-in-place slab joints. In order to improve the overall performance of the structure, the prefabricated bridge panels are also made of ultra-high performance concrete (UHPC). Due to the high strength of UHPC, the structural performance is indeed greatly improved. However, the interface between the UHPC prefabricated panel and the UHPC cast-in-place joint has become a relatively weak part, and the interface in the tensile zone is prone to cracking under the action of negative bending moment. And because the UHPC tensile strength of the prefabricated panels and cast-in-place joints on both sides is high, the cracks at the interface develop rapidly, forming plastic hinges, so that the tensile steel bars passing through the interface yield, and the structure enters the destruction stage, affecting the overall bearing capacity of the structure.

[0003] Therefore, it is necessary to solve the crack resistance problem of the interface between UHPC cast-in-place slabs. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a tensioning assembly for improving the crack resistance of the interface between UHPC cast-in-place slabs, thereby improving the crack resistance of the interface between the UHPC prefabricated slab and the UHPC cast-in-place joint.

[0005] The tension assembly for improving the crack resistance of the interface of the UHPC cast-in-place slab joint of the present invention comprises side fixing plates arranged in the UHPC prefabricated bridge deck along both sides of the joint, and tension screws across the joint fixed to the side fixing plates in a detachable tensioning manner, wherein the tension screws are distributed at equal intervals along the longitudinal direction of the joint, and the axial displacement of the tension screws is adjusted to generate opposite compressive stresses on the side fixing plates to form a plurality of local pressure-bearing areas continuously distributed along the longitudinal direction of the joint between the side fixing plates, and the tension screws comprise an inner screw arranged in the UHPC prefabricated bridge deck and an outer screw arranged on the lower end surface of the UHPC prefabricated bridge deck;

[0006] Furthermore, it also includes a plurality of intermediate fixing plates spaced apart in the joint, and inner screws are pulled between the side fixing plates and the intermediate fixing plates to form a plurality of local pressure-bearing areas continuously distributed along the longitudinal direction of the joint between the side fixing plates and the intermediate fixing plates;

[0007] Furthermore, three inner screws are horizontally arranged between each intermediate fixing plate and the corresponding side fixing plate to form a stable balanced supporting structure, and the three tension screws are simultaneously fixed to the same intermediate fixing plate;

[0008] Furthermore, the intermediate fixing plates are arranged in a manner of equal spacing along the longitudinal direction of the seam and alternating left and right positions;

[0009] Further, the number of internal screws in the area between each side fixing plate and the middle fixing plate is equal and is evenly spaced along the longitudinal direction of the joint;

[0010] Furthermore, the side fixing plates and the middle fixing plates are both perforated steel plates, the side fixing plates are welded and fixed to the steel skeleton of the UHPC prefabricated bridge deck, the middle fixing plates are welded and fixed to the steel skeleton in the joint area, and both ends of the tension screws are fixed to the perforated steel plates by anchor bolts;

[0011] Furthermore, the lower end portion of the side fixing plate extends to the outside of the lower end surface of the HPC prefabricated bridge deck for fixing the external screw.

[0012] The beneficial effects of the present invention are as follows: the tensioning assembly of the present invention for improving the crack resistance of the interface between the UHPC cast-in-place slabs generates a pair of opposite compressive stresses on the rear end area of ​​the side fixing plate steel plate located in the UHPC cast-in-place slab through the tensioning screw, forming a plurality of local pressure-bearing areas distributed continuously along the longitudinal direction in the joint area, so that the interface at the core of the area is subjected to the core pressure, thereby improving the crack resistance of the interface of the UHPC cast-in-place slab joint. The use of the tensioning assembly to enhance the crack resistance of the joint has simple construction and operation, and does not cause new weak interfaces to the original UHPC prefabricated bridge deck and cast-in-place joints; by improving the crack resistance of the interface, the overall performance of the UHPC bridge deck constructed by prefabricated assembly is improved, which promotes the application and promotion of high-performance concrete in prefabricated steel-concrete composite structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0014] Figure 1 This is the elevation drawing of the joint structure between UHPC cast-in-place slabs (without intermediate fixing plates);

[0015] Figure 2 This is another elevation view of the indirect joint structure of UHPC cast-in-place slab (with an intermediate fixed plate);

[0016] Figure 3 for Figure 2 AA section view;

[0017] Figure 4 for Figure 2 BB cross-section diagram;

[0018] Figure 5 It is a schematic diagram of the construction structure of the middle fixing plate, the inner screw and the side fixing plate;

[0019] Figure 6 for Figure 2 Force diagram of ;

[0020] Figure 7 for Figure 6 AA cross-sectional diagram of ;

[0021] Figure 8 for Figure 1 Force diagram of . DETAILED DESCRIPTION

[0022] Figure 1 This is the elevation drawing of the joint structure between UHPC cast-in-place slabs (without intermediate fixing plates); Figure 2 This is another elevation view of the indirect joint structure of UHPC cast-in-place slab (with an intermediate fixed plate); Figure 3 for Figure 2 AA section view;

[0023] Figure 4 for Figure 2 BB cross-section diagram; Figure 5 It is a schematic diagram of the construction structure of the middle fixing plate, the inner screw and the side fixing plate; Figure 6 for Figure 2 Force diagram of ; Figure 7 for Figure 6 AA cross-sectional diagram of ; Figure 8 for Figure 1Schematic diagram of force. As shown in the figure, the tension assembly for improving the crack resistance of the interface of the UHPC cast-in-place slab joint in this embodiment includes side fixing plates 3 arranged in the UHPC precast bridge deck 2 along both sides of the joint 1, and tension screws across the joint 1 and fixed to the side fixing plates 3 in a detachable tension manner, the tension screws are distributed at equal intervals along the longitudinal direction of the joint 1, and the axial displacement of the tension screws is adjusted to generate opposite compressive stresses on the side fixing plates 3 to form multiple local pressure-bearing areas 10 distributed continuously along the longitudinal direction of the joint 1 between the side fixing plates 3, the tension screws include an inner screw 4 arranged in the UHPC precast bridge deck 2 and an outer screw 5 arranged on the lower end surface of the UHPC precast bridge deck 2; the side fixing plates 3 are two integral plates, located in the UHPC precast bridge deck 2 on both sides of the joint 1, and the two side fixing plates 3 are arranged parallel to the joint 1. The tensioning screws are pulled between the two side fixing plates 3 to adjust the axial displacement of the tensioning screws and generate opposite compressive stresses on the side fixing plates 3 on both sides. The tensioning screws are divided into inner screws 4 and outer screws 5. The inner screws 4 are located in the joint 1 and pass through the joint 1 to be fixed to the side fixing plates 3 located in the UHPC precast bridge deck 2. The inner screws 4 are distributed at equal intervals along the longitudinal direction of the joint 1. The outer screws 5 are located outside the lower end surface of the UHPC precast bridge deck 2 and are fixed to the side fixing plates 3 along the end surface of the joint 1. The outer screws 5 cooperate with the inner screws 4 and the side fixing plates 3 to generate a pair of opposite compressive stresses on the rear end area of ​​the steel plate of the side fixing plates 3 located in the UHPC cast-in-place slab through the tensioning screws, forming a plurality of local pressure-bearing areas 10 distributed continuously along the longitudinal direction in the joint 1 area. The plurality of local pressure-bearing areas 10 are distributed continuously along the longitudinal direction of the joint 1 area, so that the interface at the core part of the area is subjected to the core pressure, thereby improving the crack resistance of the interface of the joint 1 of the UHPC cast-in-place slab.

[0024] In this embodiment, it also includes a plurality of intermediate fixing plates 6 arranged at intervals in the joint 1, and the inner screw rods 4 are pulled between the side fixing plates 3 and the intermediate fixing plates 6 to form a plurality of local pressure-bearing areas 10 distributed continuously along the longitudinal direction of the joint 1 between the side fixing plates 3 and the intermediate fixing plates 6; when the spacing of the joint 1 is small, only two side fixing plates 3 and the pulling screw rods are required. At this time, the side fixing plates 3 fix both the inner screw 4 and the outer screw 5, which can ensure sufficient structural stability. At this time, the local pressure-bearing areas 10 formed are distributed in a single row along the longitudinal direction of the joint 1, such as Figure 1 , Figure 8 When the spacing of the joint 1 is large, an intermediate fixing plate 6 needs to be arranged in the joint 1 area, and the intermediate fixing plate 6, the side fixing plate 3 and the tension screws form a local pressure-bearing area 10 distributed in double rows along the longitudinal direction of the joint 1, as shown in FIG. Figure 2 , Figure 7 As shown, the performance of each local pressure-bearing area 10 is ensured to be stable. At this time, the inner screw 4 is fixed by the middle fixing plate 6 and the side fixing plate 3, and the outer screw 5 is only fixed on the side fixing plate 3.

[0025] In this embodiment, three tension screws are arranged horizontally between each intermediate fixing plate 6 and the corresponding side fixing plate 3 to form a stable balanced support structure, and the three tension screws are fixed to the same intermediate fixing plate 6 at the same time; among the three tension screws, two tension screws are arranged side by side and in parallel in the same direction, and one end of the two tension screws is respectively fixed to the two ends of the intermediate fixing plate 6, and the other ends of the two tension screws are respectively fixed to the same side fixing plate 3; one end of the other tension screw is fixed to the other side fixing plate 3, and the other end is fixed to the middle section of the intermediate fixing plate 6. The two tension screws are distributed horizontally and evenly spaced along the joint 1 in a head-to-tail mode relative to the other tension screw. In this way, not only is the structural stability high, but the compressive stresses on the intermediate fixing plate 6 and the two side fixing plates 3 are the same.

[0026] In this embodiment, the intermediate fixing plates 6 are arranged in a manner of equal spacing and alternating left and right along the longitudinal direction of the joint 1; the number of tension screws in the area between each side fixing plate 3 and the intermediate fixing plate 6 is equal and is distributed in a manner of equal spacing along the longitudinal direction of the joint 1; one intermediate fixing plate 6 connects three tension screws, each intermediate fixing plate 6 is located in the same horizontal plane, and is staggered left and right along the longitudinal direction of the joint 1 (staggered up and down in the transverse direction of the joint 1). Therefore, two rows of intermediate fixing plates 6 arranged at equal spacing are formed in the longitudinal direction of the joint 1, and the spacing is the length of one intermediate fixing plate 6. In the longitudinal direction of the joint 1, each tension screw is arranged in a manner of head-to-tail connection and equal spacing in the joint 1 area.

[0027] In this embodiment, the side fixing plate 3 and the middle fixing plate 6 are both perforated steel plates. The side fixing plate 3 is welded and fixed to the steel skeleton 7 of the UHPC prefabricated bridge deck 2, and the middle fixing plate 6 is welded and fixed to the steel skeleton 9 in the joint 1 area. Both ends of the tension screw rods are fixed to the perforated steel plates by anchor bolts; the tension screw rods are all steel bars. During construction, the side fixing plate 3 is welded and fixed on the steel skeleton 7 of the UHPC prefabricated bridge deck 2, the inner screw 4 is passed through the side fixing plate 3 and tightened, and the tightening force is implemented according to the design requirements, and the prefabricated UHPC bridge deck 2 is cast and installed to the top of the steel beam; then the steel skeleton 9 of the joint 1 section between the prefabricated UHPC bridge decks is tied, and at the same time, the intermediate fixing plate 6 is welded and fixed on the steel skeleton 9 of the joint 1 section, and the inner screw 4 is passed through the intermediate fixing plate 6 and tightened, and the tightening force is implemented according to the design requirements; then the UHPC of the joint 1 is cast in situ; after the strength of the UHPC of the cast-in-situ joint 1 reaches the design requirements, the outer screw 5 is passed through the free hole of the side fixing plate 3 at the lower end of the bridge deck and tightened, and the tightening force is implemented according to the design requirements; the local crack resistance function of the interface between the UHPC prefabricated bridge deck 2 and the cast-in-situ joint 1 is improved. When the intermediate fixing plate 6 is not needed, the corresponding construction steps are also omitted.

[0028] In this embodiment, the lower end of the side fixing plate 3 extends to the outside of the lower end surface of the HPC precast bridge deck to fix the external screw 5 to ensure the stability of the structure. A pair of opposite compressive stresses are generated in the rear end area of ​​the steel plate during the tightening of the anchor bolts 8 at both ends of the tension screw, so that the interface at the core of the area is subjected to this core pressure, thereby improving its crack resistance and improving the crack resistance of the interface between the UHPC precast bridge deck 2 and the UHPC cast-in-place joint 1; the construction operation is simple, and no new weak interface is created for the original UHPC precast bridge deck 2 and the cast-in-place joint 1; by improving the crack resistance of the interface, the overall performance of the UHPC bridge deck constructed by prefabricated assembly is improved, which promotes the application and promotion of high-performance concrete in prefabricated steel-concrete composite structures.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A tensioning assembly for improving the crack resistance of the interface of a UHPC cast-in-place slab joint, characterized by: It includes side fixing plates arranged in the UHPC prefabricated bridge deck along both sides of the joint, and tensioning screws spanning the joint and fixed to the side fixing plates in a detachable tensioning manner. The tensioning screws are distributed at equal intervals along the longitudinal direction of the joint. By adjusting the axial displacement of the tensioning screws, opposite compressive stresses are generated on the side fixing plates to form a plurality of local pressure-bearing areas continuously distributed along the longitudinal direction of the joint between the side fixing plates. The tensioning screws include an inner screw arranged in the UHPC prefabricated bridge deck and an outer screw arranged on the lower end surface of the UHPC prefabricated bridge deck.

2. The tension assembly for improving the crack resistance of the interface of the UHPC cast-in-place slab joint according to claim 1 is characterized in that: It also includes a plurality of intermediate fixing plates spaced apart in the joint, and inner screws are pulled between the side fixing plates and the intermediate fixing plates to form a plurality of local pressure-bearing areas continuously distributed along the longitudinal direction of the joint.

3. The tension assembly for improving the crack resistance of the interface of the UHPC cast-in-place slab joint according to claim 2 is characterized in that: Three inner screws are horizontally arranged between each middle fixing plate and the corresponding side fixing plate to form a stable balanced supporting structure, and the three inner screws are fixed to the same middle fixing plate at the same time.

4. The tension assembly for improving the crack resistance of the interface of the UHPC cast-in-place slab joint according to claim 3 is characterized in that: The middle fixing plates are arranged in a manner of equal spacing along the longitudinal direction of the seam and alternating left and right positions.

5. The tension assembly for improving the crack resistance of the interface of the UHPC cast-in-place slab joint according to claim 4 is characterized in that: The number of inner screws in the area between each side fixing plate and the middle fixing plate is equal and is distributed at equal intervals along the longitudinal direction of the seam.

6. The tension assembly for improving the crack resistance of the interface of the UHPC cast-in-place slab joint according to claim 2, characterized in that: The side fixing plates and the middle fixing plates are both perforated steel plates. The side fixing plates are welded and fixed to the steel frame of the UHPC prefabricated bridge deck, and the middle fixing plates are welded and fixed to the steel frame in the joint area. Both ends of the tension screws are fixed to the perforated steel plates by anchor bolts.

7. The tension assembly for improving the crack resistance of the interface of the UHPC cast-in-place slab joint according to claim 1 is characterized in that: The lower end portion of the side fixing plate extends to the outside of the lower end surface of the HPC prefabricated bridge deck for fixing the external screw.

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