An externally prestressed steel-concrete composite beam using U-shaped connectors

Abstract

The present invention discloses a concrete-filled steel tube composite beam with external steel using U-shaped connectors, which includes a flange and a web. The flange is arranged horizontally and is located above the web. The web is arranged vertically, and its top end is fixedly connected to the flange to form a composite beam with a T-shaped cross-section. Among them, the web includes a U-shaped steel beam, and the top ends of the two side walls of the U-shaped steel beam are bent inward to form upper flanges. A connector is arranged above the U-shaped steel beam. The cross-section of the connector is U-shaped, and the bottom end of the connector is fixedly connected to the upper flange of the U-shaped steel beam. The top ends of the two side walls of the connector extend in a direction away from the connector to form a plurality of protrusions, and a groove is formed between two adjacent protrusions. The protrusions at the top ends of the two side walls of the connector are arranged in one-to-one correspondence. A plurality of openings are provided at the bottom of the connector. The openings penetrate the bottom of the connector and are distributed at intervals along the length direction of the connector.

Description

Technical Field

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

[0002] The concrete-filled U-shaped steel-concrete composite beam (hereinafter referred to as the concrete-filled steel box composite beam) is a T-shaped cross-section composite beam formed by combining the wing plate and the concrete-filled U-shaped steel web through different shear connectors, which gives full play to the advantages of concrete in compression and steel in tension and makes up for their respective defects. Compared with concrete beams, the concrete-filled steel box composite beam has high bearing capacity, good ductility and seismic performance, can use a smaller cross-section to bear the load, thereby reducing its own weight. At the same time, the outer steel can be used as a formwork, eliminating the need for formwork support on site and shortening the construction period. Compared with steel beams, the internal concrete provides support for the outer U-shaped steel, improves the local buckling performance of the U-shaped steel, thereby enhancing the stability and integrity of the component, reducing the steel consumption. At the same time, the internal concrete can improve the durability and fire resistance, making the comprehensive cost lower.

[0003] The prerequisite for the full play of the excellent performance of the concrete-filled steel box composite beam is that there should be sufficient shear connectors at the interface between the wing plate and the web. At present, the commonly used connectors for the interface between the wing plate and the web are channel steel, steel bar truss + hanger bars, embedded webs, etc. When using channel steel as the connector, it is easy to collide with the floor reinforcement during construction, and the position needs to be adjusted repeatedly for many times, resulting in inconvenient construction and extended construction period. When using the steel bar truss + hanger bars as the connector, the steel bar truss is welded to the upper flange of the U-shaped steel beam, and the lower end of the hanger bar has a hook, but the opening size on the U-shaped steel beam is generally small, making it extremely inconvenient to bind the hanger bars on site. When using the embedded web as the connector, the web is directly embedded in the wing plate. Since the U-shaped steel beam of this form has no upper flange, when using the steel bar truss floor slab, there is no welding position for the support vertical bars of the floor slab to be connected to the U-shaped steel beam, making it difficult to fix the floor slab, bringing inconvenience to construction. In addition, in order to ensure the stability of the U-shaped steel beam during the construction stage, additional beam bottom supports or measures to limit the lateral opening of the U-shaped steel beam need to be set, increasing the construction process. In addition, the shear and uplift resistance of this kind of connector is weak, so that the performance of the composite beam cannot be fully exerted. Summary of the Invention

[0004] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to provide a concrete-filled steel box composite beam with U-shaped connectors to solve the problems in the prior art that it is inconvenient to arrange the floor reinforcement and bind the hanger bars at the opening of the U-shaped steel beam, resulting in extended construction period, the need for additional beam bottom supports, increased construction processes, and weak shear and uplift resistance.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] An externally prestressed steel-concrete composite beam using a U-shaped connector, comprising a flange and a web. The flange is arranged horizontally and is located above the web. The web is arranged vertically, and its top end is fixedly connected to the flange to form a composite beam with a T-shaped cross-section. Among them, the web includes a U-shaped steel beam. The top ends of the two side walls of the U-shaped steel beam are bent inward to form upper flanges. A connector is arranged above the U-shaped steel beam. The cross-section of the connector is U-shaped. The length direction of the connector is the same as the length direction of the U-shaped steel beam, and the bottom end of the connector is fixedly connected to the upper flange of the U-shaped steel beam. The top ends of the two side walls of the connector extend in a direction away from the connector to form a plurality of protrusions. The protrusions are spaced apart along the length direction of the connector, and a groove is formed between two adjacent protrusions. The protrusions at the top ends of the two side walls of the connector are arranged in one-to-one correspondence. A plurality of openings are provided at the bottom of the connector. The openings penetrate the bottom of the connector and are spaced apart along the length direction of the connector.

[0007] Preferably, there is a gap between the two upper flanges of the U-shaped steel beam. The bottom end of the connector passes through the gap and extends into the U-shaped steel beam, so that the upper flange of the U-shaped steel beam is located outside the bottom end of the connector, and the upper flange of the U-shaped steel beam is fixedly connected to the lower ends of the two outer side walls of the connector.

[0008] Preferably, a through hole is provided in the protrusion of the connector. The through hole penetrates the opposite side walls of the protrusion, and the through holes in the protrusions at the top ends of the two side walls of the connector are arranged in one-to-one correspondence.

[0009] Preferably, it further includes a plurality of tension and shear resistant bars. The length direction of the tension and shear resistant bars is perpendicular to the length direction of the connector, and both ends of the tension and shear resistant bars respectively pass through the through holes in the protrusions.

[0010] Preferably, it further includes a plurality of bottom slab steel bars. The length direction of the bottom slab steel bars is perpendicular to the length direction of the connector, and both ends of the bottom slab steel bars respectively pass through the grooves on the connecting side walls of the connector.

[0011] Preferably, a plurality of top slab negative steel bars are further laid above the connector. The top slab negative steel bars are spaced apart along the length direction of the connector, and the length direction of the top slab negative steel bars is perpendicular to the length direction of the connector.

[0012] Preferably, a plurality of top beam longitudinal steel bars are laid below the top slab negative steel bars. The top beam longitudinal steel bars are respectively located inside and outside the connector. Their length direction is perpendicular to the top slab negative steel bars and is connected to the top slab negative steel bars.

[0013] The present invention also provides a preparation process for a U-shaped connector, which is used to prepare the connector in the above-mentioned externally prestressed steel-concrete composite beam using a U-shaped connector, and includes the following steps:

[0014] Step 1: Select a suitable steel plate as raw material and cut along the wavy line on the steel plate to obtain a standard unit A. The wavy line is consistent with the length direction of the steel plate;

[0015] Step 2: Cutting along the zigzag line on the side of standard cell A facing away from the wavy line to obtain standard cells B and C; after cutting, multiple spaced protrusions are formed on the side of standard cells B and C (i.e., the side facing away from the wavy line); wherein the width of the top of each protrusion is greater than the width of the bottom, so that a groove is formed between two adjacent protrusions;

[0016] Step 3: Splice and fix the edges of the two standard units B or C on one side with the wavy line, so that the edges of the two standard units B or C on one side with the wavy line are assembled to form a hexagonal opening;

[0017] Step 4: Bend both sides of the standard unit B or standard unit C with protrusions inward to form a U-shaped connector.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention adopts a U-shaped connector with protrusions and grooves at the top to make it serrated, so as to facilitate the passage of floor slab reinforcement on site, thereby solving the problem of easy collision between the floor slab reinforcement and the connector; at the same time, the serrated shape of the U-shaped connector is larger at the top and smaller at the bottom, which can enhance the embedding effect of the U-shaped connector in the concrete wing plate, thereby limiting the mutual separation and slippage of the U-shaped steel beam and the concrete wing plate, and enhancing the coordinated deformation ability of the outer steel composite beam.

[0020] 2. The present invention also provides through holes on the U-shaped connector for passing pull-out and shear reinforcement. The pull-out and shear reinforcement can further limit the separation and slippage between the U-shaped steel beam and the concrete flange, further enhancing the interaction between the flange and web of the outer steel composite beam. Therefore, there is no need to tie hanger bars on site for pull-out and shear resistance.

[0021] 3. The bottom of the U-shaped connector in the present invention is used to connect the upper flanges of the U-shaped steel girders into a whole, making the open U-shaped steel girders equivalent to a rectangular cross-section, enhancing the stable bearing capacity of the U-shaped steel girders. No additional beam bottom support is required during the construction stage, thus solving the problem that additional support needs to be set for the embedded web during the construction stage and improving the construction efficiency. Honeycomb-shaped holes are provided at the bottom of the U-shaped connector, which can facilitate the pouring of concrete inside the U-shaped steel girders, enabling the concrete inside the U-shaped steel girders, U-shaped connectors and wing plates to form a whole. At the same time, the honeycomb holes and the concrete form combined bolts, enhancing the shear resistance at the interface between the wing plate and the web of the concrete-filled steel composite beam. By using U-shaped steel girders with inturned upper flanges and U-shaped connectors with honeycomb holes, the U-shaped steel girders can be cold-formed at one time and produced fully automatically, greatly improving the production efficiency. The bottom of the U-shaped connector is provided with honeycomb-shaped holes, and the two side walls of the U-shaped connector are serrated, avoiding waste of steel cutting, and greatly reducing the processing and manufacturing costs of both. Brief Description of the Drawings

[0022] Figure 1 FIG. is a schematic structural view of a concrete-filled steel composite beam with a U-shaped connector according to the present invention.

[0023] Figure 2 is Figure 1 View A-A in

[0024] Figure 3 is a schematic structural view of the connector.

[0025] Figure 4 is a schematic view of the processing steps of the connector.

[0026] In the figure: U-shaped steel girder 1, upper flange 2, connector 3, protrusion 4, groove 5, opening 6, through hole 7, uplift and shear resistance reinforcement 8, bottom slab steel bar 9, wavy line 10, top slab negative reinforcement 11, beam top longitudinal reinforcement 12, standard unit A 13, serrated line 14, standard unit B 15, standard unit C 16. Detailed Description of the Invention

[0027] The present invention will be further described below in conjunction with the drawings and embodiments.

[0028] The present invention provides a concrete-filled steel composite beam with U-shaped connectors. The composite beam includes a flange and a web. The flange is arranged horizontally and is located above the web. The web is arranged vertically, and its top end is fixedly connected to the flange to form a composite beam with a T-shaped cross-section. Among them, the web includes a U-shaped steel beam. The top ends of the two side walls of the U-shaped steel beam are bent inward to form upper flanges. The upper flanges can provide positions for welding and fixing the support vertical bars of the steel truss floor formwork, so as to facilitate the fixation of the floor formwork on the U-shaped steel beam. A connector is arranged above the U-shaped steel beam. The cross-section of the connector is U-shaped. The length direction of the connector is the same as that of the U-shaped steel beam, and the bottom end of the connector is fixedly connected to the upper flange of the U-shaped steel beam. The top ends of the two side walls of the connector extend in a direction away from the connector to form a plurality of protrusions. The protrusions are spaced apart along the length direction of the connector, and a groove is formed between two adjacent protrusions. During actual construction, the width of the top end of the protrusion is greater than the width of the bottom end of the protrusion, forming a sawtooth-shaped connecting part that is wider at the top and narrower at the bottom. This design can enhance the anchoring effect of the U-shaped connector in the concrete flange, thereby restricting the mutual separation and slip between the U-shaped steel beam and the concrete flange and enhancing the co-deformation ability of the concrete-filled steel composite beam. The protrusions and grooves at the top ends of the two side walls of the connector are arranged in one-to-one correspondence to facilitate the passage of the floor slab steel bars on site, and solve the problem that the floor slab steel bars arranged in the concrete flange are prone to collision with the connector. A plurality of openings are provided at the bottom of the connector. The openings penetrate the bottom of the connector and are spaced apart along the length direction of the connector. Among them, the openings are regular hexagons, and this shape is similar to a honeycomb, which can form composite dowels with the concrete, enhancing the shear resistance at the interface between the flange and the web of the concrete-filled steel composite beam. At the same time, this kind of honeycomb hole can be formed by folding line cutting and staggered welding, avoiding material waste during processing. Concrete is poured into the floor slab and the U-shaped steel beam. The concrete flows into the U-shaped steel beam through the honeycomb holes at the bottom of the connector, so that the concrete inside the floor slab and the U-shaped steel beam are integrated to form a composite beam. The present invention uses the bottom of the U-shaped connector to connect the upper flanges of the U-shaped steel beam into a whole, making the open U-shaped steel beam equivalent to a rectangular cross-section, enhancing the stable bearing capacity of the U-shaped steel beam. Therefore, it is unnecessary to additionally set beam bottom supports during the construction stage or take measures to ensure the stability of the upper flange of the U-shaped steel beam, thereby reducing the construction process and improving the construction efficiency.

[0029] In specific implementation, there is a gap between the two upper flanges of the U-shaped steel girder. The bottom end of the connecting piece passes through this gap and extends into the U-shaped steel girder, such that the upper flange of the U-shaped steel girder is located outside the bottom end of the connecting piece, and the upper flange of the U-shaped steel girder is fixedly connected to the lower ends of the two outer sidewalls of the connecting piece. A through hole is provided in the protrusion of the connecting piece, which penetrates the opposite sidewalls of the protrusion, and the through holes in the protrusions at the top ends of the two sidewalls of the connecting piece correspond to each other one by one. There are also multiple tension and shear resistance bars. The length direction of the tension and shear resistance bars is perpendicular to the length direction of the connecting piece, and both ends of the tension and shear resistance bars respectively pass through the through holes in the protrusion. The tension and shear resistance bars can further limit the mutual separation and slip between the web and the flange of the encased steel composite beam, further enhancing the co-deformation ability of the encased steel composite beam. Therefore, there is no need to tie suspension bars for anti-pulling and anti-shearing on-site. The combination of the U-shaped connecting piece and the tension and shear resistance bars enhances the anti-pulling and anti-shearing ability at the interface between the flange and the web of the encased steel composite beam, solving the problem of relatively weak composite action of the embedded web composite beam. There are also multiple bottom slab steel bars. The length direction of the bottom slab steel bars is perpendicular to the length direction of the connecting piece, and both ends of the bottom slab steel bars respectively pass through the grooves on the connecting sidewalls. Multiple top slab negative steel bars are also laid above the connecting piece. The top slab negative steel bars are spaced along the length direction of the connecting piece, and the length direction of the top slab negative steel bars is perpendicular to the length direction of the connecting piece. Multiple top beam longitudinal steel bars are laid below the top slab negative steel bars. The top beam longitudinal steel bars are respectively located inside and outside the connecting piece, and their length direction is perpendicular to the top slab negative steel bars and connected to the top slab negative steel bars.

[0030] During actual construction, the U-shaped steel girder with the inwardly turned upper flange and the U-shaped connecting piece are fabricated in the factory, welded into a whole, and then transported to the site for installation. After the beam and column are connected and fixed, the steel bar truss floor formwork is arranged. The support vertical bars of the floor formwork are welded and fixed to the upper flange of the U-shaped steel girder. After the floor slab is fixed, the bottom slab steel bars of the floor slab are arranged, and then the tension and shear resistance bars, the top beam longitudinal steel bars and the top slab steel bars are arranged. Finally, concrete is poured inside the floor slab and the U-shaped steel to form a composite beam.

[0031] The present invention also provides a preparation process for the U-shaped connecting piece, as Figure 4 shown, which specifically includes the following steps:

[0032] Step 1: Select a suitable steel plate as the raw material, cut along the wavy line 10 on the steel plate to obtain the standard unit A13, and the wavy line 10 is consistent with the length direction of the steel plate;

[0033] Step 2: On the side of the standard unit A 13 away from the wavy line, cut along the serrated line 14 to obtain the standard unit B 15 and the standard unit C 16; after cutting, make the side edges (i.e., the side edges away from the wavy line) of the standard unit B 15 and the standard unit C 16 form a plurality of protrusions distributed at intervals; wherein, the width of the top of the protrusion is greater than the width of the bottom, so that a groove is formed between two adjacent protrusions, and finally the cut side edge becomes serrated, as Figure 3 shown;

[0034] Step 3: Splice and fix the edges with wavy lines of two standard units B or standard units C, so that the edges with wavy lines of the two standard units B or standard units C are assembled to form a hexagonal opening. This can maximize the avoidance of material cutting waste caused by opening circular holes. At the same time, compared with circular holes, the combined bolt action of the hexagonal holes formed by welding and the concrete poured in the U-shaped steel beam is stronger, enhancing the combined action of the flange and web of the composite steel beam with external steel.

[0035] Step 4: Bend the two side edges with protrusions of the standard unit B or the standard unit C inward to form a U-shaped connector; and, process through holes on each protrusion, and the through holes on the protrusions on both sides of the connector correspond one by one.

[0036] The processing steps of the U-shaped connector are as Figure 4 shown: Cut the steel plate along the wavy line to form the standard unit A with wavy lines on both sides, then cut the standard unit A along the serrated line and open holes on the serrations to form the standard units B and C with both wavy lines and serrated edges, then weld the two standard units B or the two standard units C along the wavy edges to form the unit D, and finally bend the unit D inward along the bending line (dotted line) to form a U-shaped connector.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and do not limit the technical solutions. 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 purpose and scope of the present technical solutions shall be covered within the scope of the claims of the present invention.

Claims

1. An externally-bonded steel-concrete composite beam using a U-shaped connector, comprising a flange and a web. The flange is arranged horizontally and is located above the web. The web is arranged vertically, and its top end is fixedly connected to the flange to form a composite beam with a T-shaped cross-section. Among them, The web comprises a U-shaped steel beam (1), the top ends of the two side walls of the U-shaped steel beam being bent inward to form an upper flange (2); the feature being that a connecting member (3) is provided above the U-shaped steel beam, the cross section of the connecting member being U-shaped, the length direction of the connecting member being consistent with the length direction of the U-shaped steel beam, and the bottom end of the connecting member being fixedly connected to the upper flange of the U-shaped steel beam; the top ends of the two side walls of the connecting member extending in a vertical direction away from the U-shaped steel beam to form a plurality of protrusions (4), the protrusions being spaced apart along the length direction of the connecting member, and a groove (5) being formed between two adjacent protrusions; the protrusions at the top ends of the two side walls of the connecting member being arranged in a one-to-one correspondence; the bottom of the connecting member being provided with a plurality of openings (6), the openings penetrating the bottom of the connecting member and being spaced apart along the length direction of the connecting member.

2. The externally prestressed steel-concrete composite beam with U-shaped connectors according to claim 1, characterized in that, There is a gap between the two upper flanges of the U-shaped steel beam, and the bottom end of the connecting piece passes through the gap and extends into the U-shaped steel beam, so that the upper flange of the U-shaped steel beam is located on the outside of the bottom end of the connecting piece, and the upper flange of the U-shaped steel beam is fixedly connected to the lower ends of the two outer side walls of the connecting piece.

3. The externally prestressed concrete composite beam with U-shaped connectors according to claim 2, wherein A through hole (7) is provided on the protrusion of the connecting piece, the through hole passing through two opposite side walls of the protrusion, and the through holes on the protrusions at the top ends of the two side walls of the connecting piece correspond to each other.

4. The externally prestressed steel-concrete composite beam with a U-shaped connecting member according to claim 2, wherein, It also includes a plurality of pull-out and shear-resistant reinforcements (8), wherein the length direction of the pull-out and shear-resistant reinforcements is perpendicular to the length direction of the connecting piece, and both ends of the pull-out and shear-resistant reinforcements respectively pass through the through holes on the protrusion.

5. The externally prestressed steel-concrete composite beam with U-shaped connectors according to claim 2, characterized in that, It also includes a plurality of bottom plate steel bars (9), the length direction of the bottom plate steel bars is perpendicular to the length direction of the connecting piece, and both ends of the bottom plate steel bars respectively pass through the grooves on the side walls of the connecting piece.

6. The externally prestressed concrete composite beam with U-shaped connectors according to claim 1, characterized in that, A plurality of plate top negative reinforcements (11) are also laid above the connecting piece. The plate top negative reinforcements are distributed at intervals along the length direction of the connecting piece, and the length direction of the plate top negative reinforcements is perpendicular to the length direction of the connecting piece.

7. The externally prestressed concrete composite beam with U-shaped connectors according to claim 6, wherein A plurality of beam top longitudinal bars (12) are laid below the slab top negative bars. The beam top longitudinal bars are respectively located on the inner and outer sides of the connectors, and their length directions are perpendicular to the slab top negative bars and connected to the slab top negative bars.

8. A preparation process of a U-shaped connecting piece, characterized in that, Preparation of a connector for a steel-clad concrete composite beam using a U-shaped connector as claimed in any one of claims 1 to 7 comprises the following steps: Step 1: Select a suitable steel plate as raw material, cut the steel plate along the wavy line (10) to obtain a standard unit A (13), where the wavy line is consistent with the length direction of the steel plate; Step 2: Cutting along the sawtooth line (14) on the side of the standard unit A away from the wavy line to obtain standard units B (15) and standard units C (16); after cutting, multiple spaced protrusions are formed on the side of the standard units B and C; wherein the width of the top of the protrusion is greater than the width of the bottom, so that a groove is formed between two adjacent protrusions; Step 3: Splice and fix the edges of the two standard units B or C on one side with the wavy line, so that the edges of the two standard units B or C on one side with the wavy line are assembled to form a hexagonal opening; Step 4: Bend both sides of the standard unit B or standard unit C with protrusions inward to form a U-shaped connector.

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