A bent web embedded U-shaped steel-concrete composite beam

Abstract

The present invention discloses a bent web embedded U-shaped steel-concrete composite beam, which comprises a U-shaped steel and a floor slab. The floor slab is located on one side of the upper end of the U-shaped steel and is fixedly connected thereto. Among them, the upper side of the U-shaped steel is an open end, and the lower side is a closed end. The upper ends of the two side walls of the open end are respectively bent inwards and extended to form upper flanges. One end of each upper flange forms a connecting part, and there is a gap between the two connecting parts, and the connecting parts are serrated. A serrated steel bar is also arranged in the gap between the two connecting parts. The serrated steel bar has a plurality of connecting protrusions and a plurality of connecting grooves and is fixedly connected to the two connecting parts of the U-shaped steel respectively. The composite beam of the present invention adopts a non-removable bottom formwork steel bar truss floor slab, which can realize the construction of horizontal members without formwork and less supports, and is fully assembled, saving construction measures cost and reducing the cost. At the same time, the bottom surface of the floor slab is flat, and thin plastering can be realized, without ceiling, reducing the decoration cost.

Description

Technical Field

[0001] The present invention relates to the technical field of building structures, and particularly relates to a bent web embedded U-shaped steel-concrete composite beam. Background Art

[0002] Steel-concrete composite beams give full play to the advantages of concrete in compression and steel in tension, and make up for their respective defects. Compared with concrete beams, steel-concrete composite beams can improve the ductility of components, reduce self-weight, and shorten the construction period; compared with steel structures, steel-concrete composite beams can enhance the stability of components and the integrity of the structure, improve durability and fire resistance, reduce the amount of steel used, and thus reduce costs.

[0003] Commonly used steel-concrete composite beams are H-shaped steel composite beams. There are obvious cold and heat bridge effects within the height range of the H-shaped steel, and the architectural appearance is poor, requiring secondary decoration, that is, increasing the decoration construction process, greatly increasing material consumption, making the economy of this type of beam poor. Therefore, U-shaped steel-concrete composite beams (referred to as U-beams for short) have emerged. The beam ribs of this type of composite beam are rectangular cross-sections, which solve the problem of secondary decoration required for H-shaped steel composite beams. In addition, the internal concrete provides support for the externally wrapped U-shaped steel, improving the local buckling performance of the U-shaped steel. The externally wrapped U-shaped steel provides restraint for the internal concrete, maintaining the integrity of the concrete and improving the performance after concrete cracking. The two work together to enhance the flexural, shear, torsional bearing capacities, stiffness and stability of the composite beam.

[0004] There are two key weak surfaces in the existing U-beams: one is the interface between the floor slab and the beam, and the other is the interface between the externally wrapped U-shaped steel and the internal concrete. The interface between the floor slab and the beam has the greatest impact on the integrity of the U-beam. Currently, the common construction measure for this weak surface is to weld shear connectors such as channel steel, angle steel, and stud bolts on the upper flange of the U-shaped steel (including inward and outward flips) to reinforce the weak surface. However, when using channel steel and angle steel connectors, the welding amount of the connectors is large and it is easy to collide with the floor slab reinforcement, making construction very inconvenient; when using stud bolt connectors, there are certain requirements for the wall thickness of the upper flange of the U-shaped steel. The wall thickness of the U-shaped steel needs to be large enough to select stud bolt connectors, but this further increases the manufacturing cost of the U-beam, making the economy of the U-beam poor. Summary of the Invention

[0005] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to provide a bent web embedded U-shaped steel-concrete composite beam to solve the problems of large construction welding amount, inconvenient construction of the connectors at the interface between the U-beam and the floor slab in the prior art, and resulting poor economy of the U-beam.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A bent web embedded U-shaped steel-concrete composite beam, comprising a U-shaped steel and a floor slab. The floor slab is located on one side of the upper end of the U-shaped steel and is fixedly connected thereto;

[0008] Wherein, the upper side of the U-shaped steel is an open end, and the lower side is a closed end; the upper ends of the two side walls of the open end are respectively bent inward and extended to form upper flanges; wherein, one end of the upper flange is bent and extended in a direction away from the closed end to form a connecting portion; there is a gap between the two connecting portions; on the connecting portion, a plurality of protrusions and grooves are distributed at intervals along its length direction, so that the connecting portion is serrated; a serrated steel bar is further provided in the gap between the two connecting portions. After the serrated steel bar is repeatedly bent and extended, a plurality of connecting protrusions and a plurality of connecting grooves are formed. The connecting protrusions are fixedly connected to the protrusions on one of the connecting portions, and the connecting grooves are fixedly connected to the protrusions on the other connecting portion; concrete is poured in the U-shaped steel and on the floor slab to form the bent web embedded U-shaped steel-concrete composite beam.

[0009] Preferably, a plurality of connecting holes are provided below the bottom of the groove.

[0010] Preferably, the floor slab includes a bottom formwork and a plurality of steel bar trusses. The steel bar trusses are distributed at intervals along the length direction of the composite beam on the bottom formwork, and their lower ends are fixedly connected to the bottom formwork; one end of the steel bar truss extends out from one side edge of the bottom formwork and is fixedly connected after abutting against the connecting portion.

[0011] Preferably, a support vertical bar is further provided at one end of the steel bar truss close to the composite beam. The support vertical bar is arranged vertically, its upper end is fixedly connected to the upper end of the steel bar truss, and its lower end is fixedly connected to the upper side of the upper flange.

[0012] Preferably, a plurality of top slab negative steel bars are further provided above the connecting portion. The top slab negative steel bars are arranged perpendicular to the length direction of the composite beam; a plurality of bottom slab lapping steel bars are further provided below the connecting portion. The length direction of the bottom slab lapping steel bars is the same as the length direction of the top slab negative steel bars, and both ends of the bottom slab lapping steel bars penetrate through the connecting holes on the two connecting portions, so that both ends of the bottom slab lapping steel bars are respectively located above the bottom formwork.

[0013] Preferably, there are also a plurality of beam top longitudinal steel bars below the top slab negative steel bars. The beam top longitudinal steel bars are arranged along the length direction of the composite beam and are fixedly connected to the top slab negative steel bars.

[0014] Preferably, when the beam top longitudinal steel bars are located between the two connecting portions, the beam top longitudinal steel bars are fixedly connected to the serrated steel bar; when the beam top longitudinal steel bars are located outside the two connecting portions, the beam top longitudinal steel bars are fixedly connected to the upper ends of the steel bar trusses.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The U-shaped steel with a bent web formed by one-time cold bending is adopted in the present invention. Compared with the U-shaped steel made by welding two C-shaped steels and a thick bottom steel plate in the prior art, the U-shaped steel in the prior art has a large welding amount, large welding residual stress and deformation, many processing procedures, and low forming efficiency. While the U-shaped steel of the present invention has no welding, high standardization, is formed at one time, has high forming efficiency, can be fully automated in production, and greatly reduces the processing and manufacturing cost, making the economy of the U-beam better.

[0017] 2. The present invention is provided with a serrated connecting part on the U-shaped steel, which cooperates with the serrated steel bars therein. Compared with the commonly used channel steel and angle steel shear connectors, the serrated connecting part and the serrated steel bars play a role in restricting the relative slip between the floor slab and the beam web and the lateral opening of the U-shaped steel. Moreover, the serrated steel bars are formed at one time, have a small cross-section, and greatly reduce the welding amount with the serrated connecting part of the U-shaped steel. At the same time, the serrated connecting part, the serrated steel bars and the bottom lap bars of the slab all play a role in restricting the relative slip and separation between the floor slab and the beam web, solving the problem of mutual interference between the floor slab steel bars and the shear connection structure of channel steel and angle steel, thus making the construction convenient.

[0018] 3. The non-removable bottom formwork steel bar truss floor slab is preferably used in the composite beam of the present invention. Compared with the ordinary cast-in-place reinforced concrete floor slab, it can realize the horizontal member without formwork and less support, and the full prefabricated construction, saving the construction measure cost and reducing the cost. Compared with the metal bottom formwork steel bar truss floor slab, the bottom surface of the floor slab is flat, thin plastering can be realized, ceiling is not required, and the decoration cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of the U-shaped steel in the present invention.

[0020] Figure 2 is Figure 1 View in the direction of A-A in

[0021] Figure 3 It is a schematic diagram of the bent web embedded U-shaped steel-concrete composite beam of the present invention.

[0022] Figure 4 is Figure 3 View in the direction of B-B in

[0023] In the figure: U-shaped steel 1, upper flange 2, connecting part 3, protrusion 4, groove 5, connecting hole 6, serrated steel bar 7, connecting protrusion 8, connecting groove 9, bottom formwork 10, steel bar truss 11, support vertical bar 12, top negative bar of slab 13, bottom lap bar of slab 14, top longitudinal bar of beam 15, connecting member 16. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The present invention will be further described below in conjunction with the drawings and embodiments.

[0025] The present invention discloses a U-shaped steel-concrete composite beam with an embedded bent web, the composite beam comprising a U-shaped steel 1 and a floor slab, the floor slab being located on one side of the upper end of the U-shaped steel and being fixedly connected thereto. Figure 1 and Figure 2 As shown. The present invention shows that floor slabs are respectively arranged on two sides of the upper end of the U-shaped steel, which are away from each other, so that the cross-section of the entire composite beam can be T-shaped. The upper side of the U-shaped steel is an open end, and the lower side is a closed end; the upper ends of the two side walls of the open end are bent inward and extended to form an upper flange 2. In the present invention, the upper flange of the U-shaped steel is flat, providing a sufficiently wide and flat installation surface for the floor slab without dismantling the bottom steel bar truss floor slab, solving the problem of narrow and uneven installation surface of the upper flange of the U-shaped steel using channel steel and angle steel connectors, and difficulty in installing the floor slab. The support vertical reinforcement 12 is connected and fixed to the upper flange 2 on site by spot welding, which can not only keep the connection surface between the floor slab and the U-shaped steel flat, but also avoid the problem of the floor slab easily falling during the pouring of concrete without setting up additional floor slab support, thereby ensuring the stability and safety of the floor slab and the U-shaped steel during the construction phase. One end of the upper flange is bent and extended in the direction away from the closed end to form a connecting portion 3. There is a gap between the two connecting portions for placing steel bars. The connection is provided with multiple protrusions 4 and grooves 5 spaced along its length, giving the connection a serrated shape. This serrated shape is larger at the top and smaller at the bottom, i.e., the width of the upper end of the protrusion 4 is greater than the width of the lower end of the protrusion 4, and the width of the groove 5 is smaller than the width of the bottom of the groove. This structure enhances the embedding of the connection within the concrete slab, thereby limiting the lateral expansion and damage of the U-shaped steel, and the relative slippage and separation between the floor slab and the beam web. At the same time, Figures 2 to 4 As shown, a serrated steel bar 7 is also provided in the gap between the two connecting parts. After repeated bending and extension, the serrated steel bar forms multiple connecting protrusions 8 and multiple connecting grooves 9. The connecting protrusions are fixedly connected to the protrusions on one of the connecting parts, and the connecting grooves are fixedly connected to the protrusions on the other connecting part. The connecting protrusions and connecting grooves on the serrated steel bar correspond one-to-one with the protrusions on the two connecting parts of the U-shaped steel. The serrated steel bar inside the U-shaped steel can, on the one hand, enhance the stability of the U-shaped steel during construction, thereby eliminating the need for supports at the bottom of the beam and reducing on-site construction procedures and construction measures costs. On the other hand, during the normal use of the composite beam, the serrated steel bar also serves to limit the lateral expansion and damage of the U-shaped steel, and the separation and slippage between the floor slab and the beam. Concrete is poured into the U-shaped steel to form the web of the U-shaped steel-concrete composite beam with an embedded bent web. At the same time, the concrete in the U-shaped steel beam flows out and is poured onto the floor slab, giving the entire composite beam a T-shaped cross-section.

[0026] In one embodiment, Figure 2As shown in the figure, a plurality of connecting holes 6 are provided below the bottom of the groove for the lapping steel bars to pass through. The bottom lapping bars of the slab pass through the connecting holes of the U-shaped steel and are embedded in the concrete. On the one hand, when there is a tendency of relative slip and separation between the floor slab and the beam, the bottom lapping bars of the slab play a dowel role, thus restricting the relative slip and separation between the floor slab and the beam. On the other hand, the bottom lapping bars of the slab transfer the internal force of the longitudinal bars at the bottom of the floor slab to the beam, thus realizing the connection between the floor slab and the composite beam.

[0027] In specific implementation, the floor slab includes a bottom formwork 10 and a plurality of steel bar trusses 11. The steel bar trusses are distributed on the bottom formwork at intervals along the length direction of the composite beam, and their lower ends are fixedly connected to the bottom formwork through connecting members 16. One side edge of the bottom formwork is flush with the outer side of the upper flange of the composite beam. When there are gaps at the construction site, in order to prevent leakage of concrete during pouring, flexible materials can be used for plugging at the site. One end of the steel bar truss extends out from one side edge of the bottom formwork. A support vertical bar 12 is also provided at one end of the steel bar truss close to the composite beam. The support vertical bar is arranged in the vertical direction, its upper end is fixedly connected to the upper chord steel bar of the steel bar truss, and its lower end is fixedly connected to the upper side of the upper flange. A plurality of top negative bars 13 of the slab are also provided above the connecting part. The top negative bars of the slab are arranged perpendicular to the length direction of the composite beam, and both ends of the top negative bars of the slab are respectively located at the upper ends of the steel bar trusses on both sides of the floor slab of the composite beam, that is: at the position of the upper chord steel bar in the steel bar truss, and can transfer force by lapping, so as to ensure the force requirements of the floor slab under the action of the negative bending moment at the support. A plurality of bottom lapping bars 14 of the slab are also provided below the connecting part. The length direction of the bottom lapping bars of the slab is the same as the length direction of the top negative bars of the slab, and both ends of the bottom lapping bars of the slab penetrate through the connecting holes on the two connecting parts, so that both ends of the bottom lapping bars of the slab are respectively located above the bottom formwork. There are also a plurality of top longitudinal bars 15 of the beam below the top negative bars of the slab. The top longitudinal bars of the beam are arranged along the length direction of the composite beam and are fixedly connected to the top negative bars of the slab. When the top longitudinal bars of the beam are located between the two connecting parts, the top longitudinal bars of the beam are fixedly connected to the serrated steel bars; when the top longitudinal bars of the beam are located outside the two connecting parts, the top longitudinal bars of the beam are fixedly connected to the upper end of the steel bar truss, that is, the upper chord steel bar.

[0028] In a construction method, the U-shaped steel and the serrated steel bars are fabricated in the factory, and then the serrated steel bars are welded to the serrated connecting part of the U-shaped steel. After the U-shaped steel is installed, the bottom lapping bars of the slab are arranged, and then the floor slab steel bars are arranged on the bottom formwork, and finally the concrete inside the U-shaped steel and the floor slab is poured. The connecting part of the U-shaped steel is serrated, larger at the top and smaller at the bottom, which enhances the biting effect between the U-shaped steel and the concrete. The serrated steel bars and the bottom lapping bars of the slab are fixed on the U-shaped steel and are also wrapped by the concrete, so that the interaction between the U-shaped steel and the concrete is very strong. Therefore, the serrated connecting part, the serrated steel bars, and the bottom lapping bars of the slab all play a role in restricting the relative slip and mutual separation between the floor slab and the beam, and the serrated connecting part and the serrated steel bars also play a role in restricting the lateral opening failure of the U-shaped steel.

[0029] After in-depth research, the present inventors found that if the top of the U-shaped steel web is not bent and the top is directly embedded in the concrete floor slab, there will be obvious defects in the actual construction process. This top structure of the U-shaped steel does not provide an installation surface for connection to the steel truss floor slab, and additional support needs to be set at the bottom of the floor slab near the U-shaped steel. At the same time, the open U-shaped steel is prone to lateral expansion without additional reinforcement measures, and the overall stability is poor. In order to ensure construction safety, additional supports need to be added at the bottom of the beam and the opening of the U-shaped steel on site, which not only increases the on-site construction operation process, resulting in an extension of the construction period, but also increases the construction cost. Moreover, since the web is not bent and directly embedded in the floor slab, the out-of-plane stiffness of the U-shaped steel is poor at the interface between the floor slab and the beam web, and it is easy to expand laterally and be damaged. Therefore, the present invention considers bending the top end of the U-shaped steel web inward to form an upper flange, which not only provides an installation and fixing plane for the steel truss floor deck, without the need for additional bottom plate support, making construction simple and cost-reduced, but also increases the out-of-plane stiffness of the U-shape, and to a certain extent limits the lateral expansion and damage of the U-shaped steel. At the same time, the connection part of the U-shaped steel is provided with serrated steel bars, which can not only increase the stability of the U-beam during the construction stage, but also further limit the lateral expansion and damage of the U-shaped steel, thereby enhancing the restraining effect of the U-shaped steel on the concrete.

[0030] Furthermore, since the web of the aforementioned U-shaped steel is unbent and has the same width from top to bottom, longitudinal reinforcement at the bottom and top of the beam, as well as stirrups, are required within the U-shaped steel. These reinforcements are difficult to tie and cumbersome to construct. Without these reinforcements, the combined effect of the floor slab and beam is significantly compromised, thus deteriorating overall performance. Therefore, the U-shaped steel web of the present invention is bent inward at its upper end, making it smaller at the top and larger at the bottom. This eliminates the need for longitudinal reinforcement at the top of the beam, along with lap reinforcement and serrated reinforcement at the bottom. These reinforcements effectively limit relative slippage and separation between the floor slab and beam, enhancing the combined effect.

[0031] At the same time, the present invention also studies the position of the bottom lap reinforcement. If it passes through the groove position in the serrated connection part of the U-shaped steel, such a design will make the bottom longitudinal reinforcement of the plate and the U-shaped steel easy to slide and separate, and cannot play the role of limiting the relative sliding and separation of the beam and the floor slab; if the bottom longitudinal reinforcement of the plate and the serrated structure of the U-shaped steel are welded on-site, on the one hand, it will increase the workload of on-site welding and reduce construction efficiency, and on the other hand, it will cause the problem of large residual stress and deformation of the serrated structure welding, which will affect the combination effect. Therefore, the bottom lap reinforcement of the plate described in the present invention does not pass directly through the serrated opening position of the U-shaped steel, but uses the bottom lap reinforcement to pass through the connection hole under the connection part to overlap the bottom longitudinal reinforcement of the plate. The connection hole can effectively limit the bottom lap reinforcement of the plate, so that the bottom lap reinforcement of the plate plays the role of limiting the relative sliding and separation of the floor slab and the beam, and at the same time does not require on-site welding, which is convenient for construction.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions shall be covered by the scope of the claims of the present invention.

Claims

1. A bent web embedded U-shaped steel-concrete composite beam, characterized in that It includes U-shaped steel (1) and a floor slab, and the floor slab is located on one side of the upper end of the U-shaped steel and is fixedly connected thereto; Among them, the upper side of the U-shaped steel is an open end, and the lower side is a closed end; the upper ends of the two side walls of the open end are respectively bent inward and extended to form upper flanges (2); among them, one end of the upper flange is bent and extended in the direction away from the closed end to form a connecting portion (3); there is a gap between the two connecting portions; on the connecting portion, a plurality of protrusions (4) and grooves (5) are distributed at intervals along its length direction, making the connecting portion serrated; a serrated steel bar (7) is also provided in the gap between the two connecting portions (3). After the serrated steel bar is repeatedly bent and extended, a plurality of connecting protrusions (8) and a plurality of connecting grooves (9) are formed. The connecting protrusions are fixedly connected to the protrusions on one connecting portion, and the connecting grooves are fixedly connected to the protrusions on the other connecting portion; the serrated steel bar is formed by repeatedly bending a steel bar into a serrated shape.

2. The bent web embedded U-shaped steel-concrete composite beam according to claim 1, characterized in that, A plurality of connecting holes (6) are provided below the bottom of the groove.

3. The bent web embedded U-shaped steel-concrete composite beam according to claim 2, wherein, The floor slab includes a bottom formwork (10) and a plurality of steel bar trusses (11). The steel bar trusses are distributed at intervals along the length direction of the composite beam on the bottom formwork, and their lower ends are fixedly connected to the bottom formwork; one end of the steel bar truss extends out from one side edge of the bottom formwork and is fixedly connected after abutting against the connecting portion.

4. The bent web embedded U-shaped steel-concrete composite beam according to claim 3, wherein, A support vertical steel bar (12) is also provided at one end of the steel bar truss close to the composite beam. The support vertical steel bar is arranged vertically, its upper end is fixedly connected to the upper end of the steel bar truss (11), and its lower end is fixedly connected to the upper side of the upper flange (2).

5. The bent web embedded U-shaped steel-concrete composite beam according to claim 4, wherein, A plurality of top negative steel bars (13) are also provided above the connecting portion. The top negative steel bars are arranged perpendicular to the length direction of the composite beam; a plurality of bottom lapping steel bars (14) are also provided below the connecting portion. The length direction of the bottom lapping steel bars is the same as that of the top negative steel bars, and both ends of the bottom lapping steel bars penetrate the connecting holes (6) on the two connecting portions, so that both ends of the bottom lapping steel bars are respectively located above the bottom formwork.

6. The bent web embedded U-shaped steel-concrete composite beam according to claim 5, characterized in that There are also a plurality of top longitudinal steel bars (15) below the top negative steel bars. The top longitudinal steel bars are arranged along the length direction of the composite beam and are fixedly connected to the top negative steel bars.

7. The bent web embedded U-shaped steel-concrete composite beam according to claim 6, wherein When the top longitudinal steel bars are located between the two connecting portions, the top longitudinal steel bars are fixedly connected to the serrated steel bar; when the top longitudinal steel bars are located outside the two connecting portions, the top longitudinal steel bars are fixedly connected to the upper ends of the steel bar trusses (11).

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