Bottom plate hole type combined box girder structure

Abstract

The utility model discloses a bottom plate opening type combined box girder structure which comprises a top plate and a bottom plate, a left web plate and a right web plate are connected between the top plate and the bottom plate, the extending direction of a combined box girder serves as the front-back direction, and the width direction of the combined box girder serves as the left-right direction. A plurality of open holes are formed in the middle of the bottom plate in the left-right direction, and the open holes are evenly formed at intervals in the front-back direction. And the bottom plate at the circumferential edge of each opening protrudes upwards to form an annular stiffening rib plate. The bottom plate is of a composite structure and comprises a steel plate layer located at the bottom end and a reinforced concrete layer poured on the steel plate layer, and a plurality of prestressed tendons are arranged in the reinforced concrete layer. Through the holes, all structures of the combined box girder are better matched with the stress condition, the overall stress performance of the combined box girder is not affected, materials used for the bottom plate are saved, the cost of the combined box girder is reduced, the dead weight of the combined box girder is reduced, and the stress efficiency is improved. The stiffening rib plates enable the structure of the steel plate layer to be more stable and not prone to distortion, the stiffening rib plates serve as formworks when bottom plate reinforced concrete is poured, the construction efficiency is improved, the construction cost is reduced, and traffic is not affected.

Description

Technical Field

[0001] The utility model relates to the technical field of construction, in particular to a composite box girder technology for bridges. Background Art

[0002] Composite box girders combine the advantages of concrete and steel, have high bearing capacity, good ductility and seismic resistance, and are widely used in bridge engineering, construction engineering and some industrial structures.

[0003] The composite box girder structure includes a top plate, a bottom plate and a web plate (including a left web plate and a right web plate) connected between the top plate and the bottom plate. As a common composite box girder structure, the top plate is a concrete top plate, the web is a corrugated steel web plate, and the bottom plate is a steel bottom plate or a reinforced concrete bottom plate.

[0004] The reinforced concrete bottom plate of the composite box girder has the following disadvantages:

[0005] 1. During construction, it is necessary to set up a scaffolding to support the bottom plate formwork, which makes on-site operations difficult and affects the normal traffic under the bridge. After the construction is completed, the formwork and scaffolding need to be removed, which results in high construction costs.

[0006] 2. The bottom plate and the web cannot be welded, the contact area is limited, and they are connected by bolts or holes through which steel bars are inserted. The connection strength between the bottom plate and the web is limited, and they are prone to cracking prematurely under tension, which has an adverse effect on the structural stiffness and durability.

[0007] The bottom plate of the composite box girder adopts a steel bottom plate, which has the following disadvantages:

[0008] 1. The steel plate is thin and prone to instability, so it can only be used for simply supported beams.

[0009] 2. Prestressed tendons can only be arranged outside the body (outside the concrete), and their stress-bearing performance is poor.

[0010] In addition, based on the shear lag effect and the relatively small bending stress in the middle of the bottom plate of the composite box girder, the middle opening design in the utility model can optimize the stress of the bottom plate and improve the stress efficiency.

[0011] The improvement idea of ​​the utility model is:

[0012] 1. Through structural design, the combined effect of the steel bottom plate and the reinforced concrete bottom plate is fully utilized to overcome the shortcomings of the poor stability of the steel bottom plate and the heavy weight of the reinforced concrete bottom plate.

[0013] 2. Design an opening structure in the middle of the bottom plate and set up stiffening ribs at the opening to further optimize the structural stress and reduce the deadweight while maintaining the greater performance advantages of the torsional stiffness and lateral bending stiffness of the closed box girder section while keeping the bending bearing capacity unchanged or slightly reduced. Utility Model Content

[0014] The utility model aims to provide a bottom plate hole-type composite box beam structure, through the hole in the middle of the bottom plate, so that the structure of each part of the composite box beam is more matched with the stress condition, and the bottom plate material is saved.

[0015] To achieve the above-mentioned purpose, the bottom plate opening type composite box beam structure of the utility model comprises a top plate and a bottom plate, and a left web plate and a right web plate are connected between the top plate and the bottom plate. The utility model is characterized in that: the extension direction of the composite box beam is the front-to-back direction, and the width direction of the composite box beam is the left-to-right direction; a plurality of openings are provided in the middle part of the bottom plate in the left-to-right direction, and the openings are evenly spaced along the front-to-back direction.

[0016] The bottom plate at the circumferential edge of each opening is protruded upward with an annular stiffening rib plate.

[0017] The bottom plate is a composite structure, including a steel plate layer at the bottom and a reinforced concrete layer cast on the steel plate layer. Connectors are provided between the steel plate layer and the reinforced concrete layer, and between the web plate and the reinforced concrete layer. The connectors are all bolts, perforated steel plates or perforated steel sections; the bottom end of the web plate is welded to the steel plate layer.

[0018] A plurality of prestressed tendons are arranged in the reinforced concrete layer, and each prestressed tendon extends in the front-rear direction.

[0019] The utility model has the following advantages:

[0020] The utility model arranges a plurality of openings on the bottom plate of the composite box girder at even intervals in the front-to-rear direction, thereby reducing the influence of the openings on the bearing capacity and stiffness of the steel girder; by arranging the openings at the locations where the structure is subjected to less stress, the structures at various locations of the composite box girder are more closely matched with the stress conditions, which neither affects the overall stress performance of the composite box girder nor saves materials for the bottom plate, thereby reducing the cost of the composite box girder, reducing the deadweight of the composite box girder, and improving the stress efficiency.

[0021] The stiffening ribs have dual technical functions. One is that they strengthen the structural strength of the bottom plate at the opening, making the steel plate structure more stable and less prone to deformation. It not only compensates for the negative impact of the opening on the structural strength to a certain extent, but also is more stable than the flat steel plate structure and is less prone to deformation due to the bridge deck load. The other technical function is that it can be used as a template for pouring the bottom plate reinforced concrete. There is no need to set up scaffolding before construction, which will not affect the normal traffic under the bridge. There is no trouble of dismantling the scaffolding after construction, which not only improves construction efficiency and reduces construction costs, but also does not affect traffic.

[0022] In the utility model, the bottom plate adopts a composite structure of a steel plate layer and a reinforced concrete layer, with the steel plate layer as the main load-bearing structure. The reinforced concrete layer has a large rigidity, which restrains the buckling and distortion of the bottom plate steel plate, making the overall compression stability of the combined bottom plate better, so that the combined box beam of this overall structure can be used not only for simply supported beams, but also for continuous beam design. The connector ensures the common load-bearing performance of the steel plate layer and the reinforced concrete layer.

[0023] The bottom end of the web is welded to the steel plate layer, and the bottom of the web is connected to the reinforced concrete layer through a connector, so that the connection rigidity between the corrugated steel web and the composite bottom plate (the composite structure of the bottom plate) is large, avoiding local cracking problems caused by too small a connection surface.

[0024] The overall structure of the utility model has the anti-torsion and transverse bending performance of a nearly closed cross section, and has large torsional rigidity and transverse bending rigidity.

[0025] A number of prestressed tendons can be arranged in the reinforced concrete layer of the base plate to reduce the number of external prestressed tendons and improve the reliability of the structural force performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a composite box girder structure with bottom plate openings.

[0027] Figure 2 yes Figure 1 AA section view.

[0028] Figure 3 It is a three-dimensional structural schematic diagram of the bottom plate opening type composite box girder structure.

[0029] Figure 4 It is a three-dimensional structural schematic diagram of the bottom plate open-hole composite box girder structure after removing the top plate.

[0030] The composite box girder is in detail shape in the front and rear directions. For the convenience of clear expression, Figures 1 to 4 Only one section of the composite box girder is shown, that is, a section of the composite box girder structure is cut from the overall length direction of the bottom plate open hole composite box girder structure.

[0031] Figure 5 yes Figure 2 Enlarged view of point A in the middle. DETAILED DESCRIPTION

[0032] like Figures 1 to 5 As shown, the bottom plate opening type composite box girder structure of the utility model comprises a top plate 1 and a bottom plate, a left web plate 3 and a right web plate 4 are connected between the top plate 1 and the bottom plate, the extension direction of the composite box girder (bridge) is the front-to-back direction, and the width direction of the composite box girder is the left-to-right direction; wherein, the top plate 1 is a reinforced concrete top plate 1, and the left web plate 3 and the right web plate 4 are both made of corrugated steel.

[0033] The bottom plate is provided with a plurality of vertically transparent openings 5 ​​in the middle of the left-right direction, and the openings 5 ​​are evenly spaced in the front-to-back direction. Since the figure only shows a section of the combined box girder, there is a semicircular opening 5 on each side of the front and back of the overall circular opening 5 in the middle (this is because half of the opening 5 is cut off).

[0034] The utility model arranges a plurality of openings 5 ​​on the bottom plate of the combined box girder at even intervals in the front-to-rear direction, thereby reducing the influence of the openings on the bearing capacity and stiffness of the steel girder; by arranging the openings 5 ​​at the locations where the structure is subjected to less stress, the structures at various locations of the combined box girder are more closely matched with the stress conditions, which neither affects the overall stress performance of the combined box girder, nor reduces the materials used for the bottom plate, thereby reducing the cost of the combined box girder, reducing the deadweight of the combined box girder, and improving the stress efficiency.

[0035] The bottom plate at the circumferential edge of each opening 5 protrudes upward with an annular stiffening rib 6. The stiffening rib 6 has a dual technical role. One is to strengthen the structural strength of the bottom plate at the opening 5, making the steel plate layer structure more stable and less prone to distortion. It not only compensates for the negative impact of the opening 5 on the structural strength to a certain extent, but also is more stable than the flat steel plate structure and less prone to distortion due to the bridge deck load. Another technical role is that it can be used as a template for pouring reinforced concrete on the bottom plate. There is no need to set up a scaffolding before construction, which will not affect the normal traffic under the bridge. There is no need to dismantle the scaffolding after construction, which not only improves construction efficiency and reduces construction costs, but also does not affect traffic.

[0036] The bottom plate is a composite structure, including a steel plate layer 7 at the bottom and a reinforced concrete layer 8 cast on the steel plate layer 7 and located between the left web 3 and the right web 4. Connectors are provided between the steel plate layer 7 and the reinforced concrete layer 8, and between the web and the reinforced concrete layer 8. The connectors are all bolts, perforated steel plates or perforated steel sections; one end of the connector is connected to the steel plate layer 7 and the other end extends into the reinforced concrete layer 8. The bottom end of the web is welded to the steel plate layer 7. The connectors are conventional technology and are not shown in the figure.

[0037] In the present invention, the bottom plate adopts a composite structure of a steel plate layer 7 and a reinforced concrete layer 8, with the steel plate layer 7 as the main force-bearing structure, and the reinforced concrete layer 8 has a large rigidity, which plays a role in restraining the buckling and distortion of the bottom plate steel plate, so that the overall compression stability of the combined bottom plate is better, so that the combined box beam of this overall structure can be used not only for simply supported beams, but also for continuous beam design. The connector ensures the common force-bearing performance of the steel plate layer 7 and the reinforced concrete layer 8.

[0038] The bottom end of the web is welded to the steel plate layer 7, and the bottom of the web is connected to the reinforced concrete layer 8 through a connector, so that the connection rigidity between the corrugated steel web and the composite bottom plate (the composite structure of the bottom plate) is large, avoiding local cracking problems caused by too small a connection surface.

[0039] The overall structure of the utility model has the anti-torsion and transverse bending performance of a nearly closed cross section, and has large torsional rigidity and transverse bending rigidity.

[0040] The reinforced concrete layer 8 is provided with a plurality of prestressed tendons 9 (of course, the prestressed tendons 9 may not be provided provided that the mechanical properties required by the bridge design objectives can be met), and each prestressed tendon 9 extends in the front-to-back direction. Of course, in addition to providing the prestressed tendons 9 inside the body, the prestressed tendons 9 may also be provided outside the body. A plurality of prestressed tendons 9 may be provided in the reinforced concrete layer 8 of the bottom plate, so as to reduce the number of prestressed tendons 9 outside the body and improve the reliability of the structural force performance.

[0041] The improvement points of the utility model are concentrated on the bottom plate, and the top plate 1 and the web plate of the composite box beam are the original structure. The thickness of the steel plate layer 7 in the utility model is less than the thickness of the bottom plate of the previous steel plate layer 7 (without the concrete layer). Before pouring the reinforced concrete layer 8, the bottom end of the corrugated steel web is welded to the steel plate layer 7 in advance; the composite box beam is relatively long in the front and rear directions, and only a section of the composite box beam structure is shown in the attached figure; the front and rear formworks are used at the front and rear ends of the composite box beam to connect with the steel plate layer 7 and the corrugated steel web, and the corrugated steel web, the front and rear formworks and the annular stiffening ribs 6 together constitute the formwork structure for pouring concrete. Since this formwork structure only needs to support the formwork at the front and rear ends of the composite box beam, there is no need to set up a full-house scaffolding. Connectors are respectively arranged on the corrugated steel web and the steel plate layer 7 in the direction of the reinforced concrete layer 8 to be poured, and then reinforced concrete is poured on the steel plate layer 7 in the formwork structure, and the connectors are poured inside. After solidification and curing, the reinforced concrete layer 8 is formed, forming the bottom plate opening 5-type composite box girder structure of the present invention.

[0042] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A bottom plate opening type composite box beam structure, comprising a top plate and a bottom plate, wherein a left web plate and a right web plate are connected between the top plate and the bottom plate, and characterized in that: The extension direction of the combined box beam is the front-to-back direction, and the width direction of the combined box beam is the left-to-right direction; a plurality of openings are arranged in the middle of the bottom plate in the left-to-right direction, and the openings are evenly spaced along the front-to-back direction.

2. The bottom plate opening type composite box beam structure according to claim 1 is characterized in that: The bottom plate at the circumferential edge of each opening is protruded upward with an annular stiffening rib plate.

3. The bottom plate hole-type composite box beam structure according to claim 1 or 2, characterized in that: The bottom plate is a composite structure, including a steel plate layer at the bottom and a reinforced concrete layer cast on the steel plate layer. Connectors are provided between the steel plate layer and the reinforced concrete layer, and between the web plate and the reinforced concrete layer. The connectors are all bolts, perforated steel plates or perforated steel sections; the bottom end of the web plate is welded to the steel plate layer.

4. The bottom plate opening type composite box beam structure according to claim 3 is characterized in that: A plurality of prestressed tendons are arranged in the reinforced concrete layer, and each prestressed tendon extends in the front-rear direction.

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