Thin-wall top flange truss and manufacturing method

Abstract

The invention discloses a thin-wall top flange truss and a manufacturing method. The thin-wall top flange truss comprises a top flange and a steel bar web member. The upper flange is composed of a web and legs arranged on the two sides of the web, the legs are arranged below the web, and the included angle between the legs and the web is not smaller than 90 degrees and not larger than 135 degrees. The thickness of the upper flange ranges from 0.8 mm to 3 mm. The length of the upper flange foot limb ranges from 10 mm to 20 mm. Webs and legs of the upper flange are formed by cold bending of thin steel plates; the reinforcing steel bar web members are formed by continuously bending reinforcing steel bars; the integral oblique angle of the steel bar web member is consistent with that of the upper flange foot limb, and the steel bar web member and the foot limb are integrally welded together. In the device, the thin-wall cold-bending channel steel with the bevel angle is adopted as the upper flange of the truss, effective connection of the steel bar web member and the upper flange is facilitated, the strength of the upper flange is effectively exerted, under the same steel material, the maximum inertia moment and the optimal mechanical property can be achieved, and under the same bevel angle of the steel bar web member and the vertical plane, the rigidity of the steel bar web member is improved. And the maximum width of the lower side of the truss is achieved.

Description

Technical Field

[0001] The present invention relates specifically to the technical field of construction engineering, in particular to a thin-walled upper flange truss and a manufacturing method thereof, which can be widely applied to floor slabs and beams of various buildings. Background Art

[0002] The trusses used in composite floor slabs or truss floor decks in existing technologies are mostly steel bar or steel tube trusses, which are characterized by upper flanges made of steel bars, steel tubes, channel steels, or various steel sections. Among them, steel bars and steel tubes are the most widely used upper flanges. Whether steel bars or steel tubes, they all have the following problems:

[0003] The web members are spaced relatively close together at the troughs. Conventional trusses have a spacing of approximately 80mm between web members at these troughs. While the use of steel tubes in the patent (CN 119825071 A) slightly increases the spacing between the web members, the increased steel content due to the use of steel tubes limits the increase. This is detrimental to improving the lateral bending strength of composite slabs, floor decks, and thin base beams. The steel plates between the trusses of the floor decks in the same truss combination are prone to deformation, posing a safety risk. Furthermore, the concrete base between the trusses of thin-base composite slabs in the same truss combination is susceptible to cracking.

[0004] When the upper flange is constructed of steel bars, steel pipes, or section steel, the distance between the centroid of the upper flange section and the centroid of the truss bottom chord is too small for the same cross-section steel consumption. This significantly reduces the truss's moment of inertia, resulting in lower flexural strength and stiffness. This results in shorter spans for precast slabs and floor decks in conjunction with the same truss. The upper flange is also farther away from the top surface of the concrete slab after pouring, significantly reducing the upper flange's utilization within the concrete slab and hindering the full utilization of the material's strength. This is described in patent (CN 119825071 A).

[0005] The connection strength between the web and the top flange is insufficient. Steel pipes or rebar serve as the top flange. Since both the rebar and the pipe have circular cross-sections, the web and flange intersect at a single point, resulting in a single connection. This connection strength cannot guarantee the truss's load-bearing properties. As described in the following documents: Patents (CN 214614894 U) and (CN 214614890 U) use spot welding at the connection points between the pipe and rebar. However, the weld contact points are too small to guarantee interoperability between the top chord and the web. Patent (CN119531599A) mentions resistance spot welding of the top chord and the web in a reinforced steel truss. Summary of the Invention

[0006] To this end, the present invention proposes a thin-walled upper flange truss and its manufacturing method to improve the truss' out-of-plane strength, enhance the truss's in-plane bending stiffness and strength, and provide a more reliable connection between the steel web and the upper flange, while reducing connection processing costs. This solves and optimizes the problems in the aforementioned background art.

[0007] To achieve the above-mentioned objectives, the present invention discloses a thin-walled upper flange truss and a manufacturing method, which includes: an upper flange, which is formed by bending a thin steel plate with a thickness of 0.8~3mm, and includes a web and legs arranged on both sides of the web, the legs are below the web, the angle between the legs and the web is 90°~135°, and the length of the legs is 10~20mm; a steel web, which is composed of continuously bent steel bars, and its inclination is consistent with the inclination of the legs, and each crest node of the steel web is welded to the legs.

[0008] Furthermore, as a preferred embodiment, a gap is formed at the lower edge of the upper flange leg at a position corresponding to the trough of the steel bar web, and a tooth-like stagger is formed with the position without a gap.

[0009] The tooth-like staggered shape allows adjacent steel plates to be staggered during steel cutting, concentrating more steel on the upper flange web. This results in improved mechanical properties with the same steel usage. The tooth shape satisfies the connection requirements with the steel web and meets the force transmission requirements between the steel web and the flange.

[0010] Furthermore, preferably, the steel web is located on the inner side or outer side of the upper flange foot.

[0011] Furthermore, preferably, the upper flange surface is provided with a reinforcement pattern, and the reinforcement pattern is at least one of a transverse corrugated rib, a longitudinal reinforcing rib, or an oblique indentation, and the pattern depth is 0.2 to 0.8 mm.

[0012] The upper flange is constructed from bent thin steel plate, and its local yield strength can be enhanced through indentations or longitudinal and transverse ribs. After concrete pouring, the upper flange is very close to the concrete top, which can withstand the tensile forces on the concrete surface and prevent cracking. The notches or indentations on the upper flange strengthen the bond between the upper flange and the concrete, further enhancing the mechanical properties of the thin steel in the upper flange.

[0013] Furthermore, preferably, the steel web is bent to form a horizontal platform at the crest.

[0014] Furthermore, preferably, the steel web is bent outward at the trough to form an outward-facing "X" shape.

[0015] Furthermore, preferably, a thin steel plate is welded to the web of the steel bar at the trough, and the thickness of the thin-walled steel plate is 0.5-1.5 mm.

[0016] The thin-walled upper flange trusses welded to thin steel plates form a truss floor deck, significantly improving performance and saving steel compared to existing truss floor decks. If the steel plate is thinner (less than 0.5 mm), the base plate rigidity is weak and cannot meet local load-bearing requirements. Thicker than 1.5 mm, the steel consumption is high, making it uneconomical.

[0017] Furthermore, preferably, a lower flange steel with a diameter of 6 to 12 mm is welded at the trough of the steel web, and the steel is parallel to the upper flange.

[0018] Furthermore, preferably, the lower flange steel is double-layered, the upper lower flange steel is steel bar, and the lower lower flange steel is steel bar or flat steel.

[0019] Further, as a preference, the upper lower flange steel is on the inside or outside of the steel bar web, and the lower lower flange steel is on the inside or outside of the steel bar web or below or above the trough.

[0020] The troughs of the steel webs are connected to the concrete or metal baseplate. The troughs are too close to the concrete bottom surface and do not meet the requirements for the steel cover. Welding the steel above the troughs not only increases the strength and rigidity of the truss, but also allows the steel to be used as load-bearing reinforcement for the floor slab after concrete pouring.

[0021] Furthermore, as a preference, the welding of the steel web members to the upper flange side plates, the welding of the steel web members to the bottom plate steel plate, and the welding of the lower flange steel bars to the steel web members all adopt resistance welding technology.

[0022] Compared to gas shielded welding, resistance welding (RW) minimizes consumables and costs when welding the web to the flange. The present invention's structural form makes resistance welding feasible. In contrast, existing technologies, which use steel pipes or square tubes for the upper flange, cannot use resistance welding. This is because resistance welding requires heating the weldment to a molten state and applying a certain amount of pressure. Using resistance welding on the steel pipe will inevitably cause significant deformation and fail to achieve the desired weld strength.

[0023] Furthermore, as a preferred embodiment, a concrete base plate is connected to the trough of the steel web, the concrete base plate adopts C35-C60 concrete, and orthogonally distributed transverse steel bars and longitudinal steel bars are provided in the concrete base plate.

[0024] Furthermore, as a preferred embodiment, the longitudinal reinforcement is prestressed reinforcement

[0025] The thin flange truss is combined with the concrete base plate, and prestressed steel bars are arranged longitudinally on the concrete base plate to form a prestressed concrete composite plate. This can effectively exert the performance of the truss of the present invention, improve the stiffness and strength of the composite plate, and improve the span capacity of the composite plate. At the same time, the upper flange of the truss of the present invention can also participate in the force-bearing effect of the concrete floor behind the composite plate.

[0026] Furthermore, preferably, the concrete base plate is fiber reinforced concrete with a plate thickness of 10-25 mm or concrete with a plate thickness of 10-25 mm and a welded steel mesh with a diameter of 2-5 mm.

[0027] The thin flange truss is combined with a thin concrete base plate, and a wire mesh or fiber reinforcement is set in the concrete base plate to increase the strength of the thin concrete base plate. A thin-base concrete composite plate is formed together with the truss of the present invention, which can effectively exert the performance of the truss of the present invention, improve the stiffness and strength of the composite plate, and improve the span capacity of the composite plate. At the same time, the upper flange of the truss of the present invention can also participate in the force-bearing effect of the concrete floor behind the composite plate.

[0028] Furthermore, preferably, the trough of the steel web is connected to a concrete composite beam, and longitudinal stress-bearing bars and stirrups are arranged in the concrete composite beam. The diameter of the longitudinal stress-bearing bars is 12~25mm, the stirrup spacing is 50~250mm, and the thickness of the concrete composite beam is 80mm~150mm.

[0029] The invention also discloses a production method thereof, which is characterized in that it comprises the following steps:

[0030] S1. Steel Strip Straightening: A three-roll straightening machine is used to straighten cold-rolled steel strip with a thickness of 0.8-3mm at a straightening speed of 2-5m / min. The flatness error after straightening is ≤1mm / m.

[0031] S2. Synchronous Forming: The straightened steel strip is fed into the roll forming machine, while rebar with a diameter of 6-12 mm is fed into the synchronous bending device. The speed of the roll forming rollers is synchronized with the rebar bending rhythm.

[0032] S3. Positioning and clamping: A pneumatic clamp is provided on the continuous production line to position the formed upper flange (1) and the bent steel web (2) at the node with a positioning accuracy of ±0.5mm;

[0033] S4. Automatic welding: Use a multi-electrode resistance welding machine for wave node welding, with a welding pressure of 200-400N, an electrode travel speed of 1-3m / min, and a welding temperature controlled at 70%-85% of the steel melting point.

[0034] The present invention adopts the above technology and has the following beneficial effects compared with the existing technology:

[0035] 1. The truss's in-plane and out-of-plane stiffness is significantly improved. The present invention utilizes thin-walled cold-formed steel as the upper flange. While maintaining the same steel usage, the steel can be expanded to a greater width, allowing for greater distance between the two truss legs. The upper flange is combined with the floor decking and composite decking, increasing the truss's out-of-plane stiffness and strength. The floor decking or composite decking between the trusses also increases stiffness and strength, significantly improving crack resistance. The increased steel width also enhances the lateral stability of the upper flange.

[0036] 2. With the same steel content, the truss achieves maximum in-plane bending stiffness and strength, allowing for a greater span without bracing. With the same steel content, the centroid of the thin-walled upper flange is further from the bottom chord, increasing the truss's moment of inertia. This increases the truss's bending stiffness and strength by approximately 20% compared to existing technologies, thereby increasing the span of floor decks or composite slabs.

[0037] 3. After the floor slab is cast, the upper flange steel utilization rate is increased. After the upper flange is unfolded, the distance between the upper flange centroid and the top of the cast floor slab is reduced, further enhancing the upper flange's strength. This also increases the contact surface between the upper flange and the concrete, improving the bond between the concrete and the upper flange and thus fully utilizing the upper flange's strength. This is especially true when the assembled floor slab or deck is used in a span beam, maximizing the upper flange steel utilization and reducing steel consumption.

[0038] 4. The connection of the truss is more reliable and the stress stability of the truss is better. The foot of the thin-walled upper flange is in full contact with the steel web, which can ensure the connection strength between the steel web and the truss, avoid the arc area caused by the bending of the steel web, and effectively exert the strength and rigidity of the truss.

[0039] 5. Truss production is simpler, more energy-efficient, and less expensive. The cold-bent upper flange legs are in full contact with the steel web, allowing resistance welding to connect the upper flange and the steel web, saving welding materials. This makes the welding process simpler than that of the upper flange of section steel and saves more welding materials than that of the upper flange of steel pipes using gas shielded welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the upper flange structure of a thin-walled upper flange truss;

[0041] Figure 2 Schematic diagram of the upper flange structure of a thin-walled upper flange truss;

[0042] Figure 3 Schematic diagram of the upper flange structure of a thin-walled upper flange truss;

[0043] Figure 4 This is a schematic diagram of the structure of a thin-walled upper flange truss;

[0044] Figure 5 This is a schematic diagram of the structure of a thin-walled upper flange truss;

[0045] Figure 6 This is a schematic diagram of the structure of a thin-walled upper flange truss;

[0046] Figure 7 This is a schematic diagram of the structure of a thin-walled upper flange truss;

[0047] Figure 8This is a schematic diagram of the structure of a thin-walled upper flange truss;

[0048] Figure 9 This is a schematic diagram of the structure of a thin-walled upper flange truss;

[0049] Figure 10 This is a structural diagram of a thin-walled upper flange truss combined with a thin steel plate;

[0050] Figure 11 This is a structural diagram of a thin-walled upper flange truss combined with a concrete slab (thickness greater than 30mm);

[0051] Figure 12 This is a structural diagram of a thin-walled upper flange truss combined with a concrete slab (thickness 10~25mm);

[0052] Figure 13 This is a structural diagram of a thin-walled upper flange truss combined with a concrete composite beam;

[0053] Figure 14 This is a structural diagram of a thin-walled upper flange truss combined with a concrete composite beam.

[0054] In the figure: 1. Upper flange; 1-1. Foot; 1-2. Web; 3. Lower flange steel; 3-1. Upper lower flange steel; 3-2. Lower lower flange steel; 4. Thin steel plate; 5. Concrete base plate; 6. Transverse reinforcement; 7. Concrete composite beam; 8. Longitudinal reinforcement; 9. Stirrups; 10. Longitudinal tension reinforcement. DETAILED DESCRIPTION

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0056] Example 1: Please refer to the attached Figure 1-5 The present invention provides a technical solution: a thin-walled upper flange truss and a manufacturing method thereof, which comprises: an upper flange, which is formed by bending a thin steel plate with a thickness of 0.8 to 3 mm, and includes a web and legs arranged on both sides of the web, the legs are below the web, the angle between the legs and the web is 90° to 135°, and the length of the legs is 10 to 20 mm; a steel web, which is composed of continuously bent steel bars, and its inclination is consistent with the inclination of the legs, and each crest node of the steel web is welded to the legs.

[0057] In this embodiment, 0.8-3mm steel plates are cold-bent into upper flanges with webs and legs. The purpose is to expand the same steel material as much as possible, so that the truss obtains better mechanical properties, and at the same time meets the connection requirements of the steel web and the legs and the local stability of the upper flange steel plate. If it is less than 0.8mm, the connection between the steel web and the legs requires gas shielded welding (because resistance welding is easy to burn through), and the web width is too large, which will cause local buckling. If it is greater than 3mm, the expansion of the steel web is limited, and the performance of the present invention cannot be better achieved. The leg length is 10-20mm, so that the leg can meet the needs of connecting with the steel web and enhancing the stiffness outside the plane of the upper flange. The leg length is minimized as much as possible, the centroid of the upper flange is as close to the top as possible, the distance from the lower chord of the truss rod is increased, and the centroid of the cross section is closer to the top surface of the finished concrete. The angle between the foot and the upper flange is controlled at 90 to 135 degrees. With the expansion of the upper flange width, the distance between the lower ends of the two steel webs is increased, forming a spatial structure between the steel webs, the upper flange and the bottom plate, thereby enhancing the stiffness and strength of the bottom plate outside the truss. At the same time, the angle should not be too large, otherwise the length of the steel web will increase, the slenderness ratio will be enhanced, the internal force of the rod will increase, the shear deformation of the truss will increase, and the in-plane stiffness of the truss will decrease. The upper flange is formed by cold bending, which is simple to process, energy-saving and low-cost. The inclination angle of the foot and the web is the same as the inclination angle of the steel web and the web, so that the foot and the steel web are in full contact. The relationship between the steel web and the upper flange is a line-surface relationship, and the connection strength is more reliable and stable, which can ensure that the mechanical properties of the upper flange and the steel web are fully utilized, while also strengthening the constraint of the steel web on the upper flange.

[0058] Furthermore, the lower edge of the upper flange foot forms a gap at the position corresponding to the trough of the steel web. Figure 2 、 Figure 3 and Figure 5 As shown, the steel strips can be staggered during the forming process to reduce the amount of steel used in the legs and use more steel in the web, thereby further improving the performance of the truss.

[0059] Furthermore, the upper flange surface is provided with reinforcing patterns, which are at least one of transverse corrugated ribs, longitudinal reinforcing ribs, or diagonal indentations, with a depth of 0.2 to 0.8 mm. For thin-walled structures, the presence of concave and convex indentations or ribs can increase the out-of-plane stiffness of the plate, reduce localized instability, and thus enhance the performance of the truss. Furthermore, the indentations, concave and convex indentations, or transverse or longitudinal ribs can enhance the bond between the upper flange and the post-formed concrete, effectively utilizing the mechanical properties of the upper flange during structural use and further reducing steel consumption.

[0060] Example 2: The same as Example 1, except that a lower flange steel bar with a diameter of 6 to 12 mm is welded at the trough of the steel web, and the steel bar is parallel to the upper flange. Figure 6

[0061] In this example, when rebar is welded to the troughs of the web members, a complete truss is formed. This can be used for composite floors with weak base plates, such as thin, unreinforced concrete base plates. It can also be used to strengthen weak base plates, such as when a trussed steel deck requires a large span and the strength and stiffness provided by the base plate alone are insufficient. Reinforcement in the lower flange can be added to increase the strength and stiffness of the component. Furthermore, the lower flange reinforcement can serve as the concrete's load-bearing base reinforcement, eliminating material waste.

[0062] Example 3: It is basically the same as Example 1, except that the trough of the steel web is connected with the thin steel plate, such as Figure 7 As shown, a truss floor deck is formed, which gives full play to the in-plane stiffness and out-of-plane stiffness of the thin-flange truss. Compared with the traditional steel truss floor deck, on a floor deck of the same width, the number of thin-flange trusses is less than that of steel trusses, and the mechanical properties are better.

[0063] Example 4: basically the same as Example 1, except that the trough of the steel web is connected to the concrete base plate to form a concrete composite slab.

[0064] Furthermore, the longitudinal reinforcement of the concrete composite slab is prestressed, e.g. Figure 8 As shown in the figure, the thickness of the bottom plate is 30~50mm, and the stiffness of the bottom plate outside the truss is relatively weak. The use of thin flange trusses can effectively enhance the strength of the concrete bottom plate outside the truss and reduce the cracking of the bottom plate.

[0065] Furthermore, the concrete base plate adopts a 10~25mm thick fiber-reinforced base plate or a wire mesh base plate, such as Figure 9 As shown in the figure, the strength and stiffness of the bottom plate in the vertical direction of the truss are weaker. The use of thin flange trusses can effectively enhance the strength of the concrete bottom plate outside the truss and reduce the cracking of the bottom plate.

[0066] Example 5: It is basically the same as Example 1, except that the concrete composite beam is connected to the trough of the steel web. The longitudinal force reinforcement and stirrups are arranged in the concrete composite beam. The diameter of the longitudinal reinforcement is 12-25mm, the stirrup spacing is 50-250mm, and the thickness of the concrete composite beam is 80mm-150mm. Figure 10 、 Figure 11 .

[0067] In this example, the truss of the present invention is combined with a concrete base plate and stirrups to form a thin-base concrete composite beam, and the truss is used to reinforce the strength and rigidity of the thin-base concrete plate. Because concrete composite beams are generally long and subject to greater stress, when the truss is placed, the stirrups need to be tied first and then the truss needs to be inserted. In addition, the truss needs to meet a certain rigidity, and the truss of this invention meets the above conditions. Compared with traditional trusses, the truss of the present invention has the characteristics of light weight per unit length and high strength, making the truss placement simpler and more convenient.

[0068] A method for manufacturing a thin-walled upper flange truss, characterized in that it comprises the following steps:

[0069] S1. Steel Strip Straightening: A three-roll straightening machine is used to straighten cold-rolled steel strip with a thickness of 0.8-3mm at a straightening speed of 2-5m / min. The flatness error after straightening is ≤1mm / m.

[0070] S2. Synchronous Forming: The straightened steel strip is fed into the roll forming machine, while rebar with a diameter of 6-12 mm is fed into the synchronous bending device. The speed of the roll forming rollers is synchronized with the rebar bending rhythm.

[0071] S3. Positioning and clamping: A pneumatic clamp is provided on the continuous production line to position the formed upper flange (1) and the bent steel web (2) at the node with a positioning accuracy of ±0.5mm;

[0072] S4. Automatic welding: Use a multi-electrode resistance welding machine for wave node welding, with a welding pressure of 200-400N, an electrode travel speed of 1-3m / min, and a welding temperature controlled at 70%-85% of the steel melting point.

[0073] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A thin-walled upper flange truss, characterized in that: include: The upper flange (1) is formed by bending a thin steel plate with a thickness of 0.8 to 3 mm, and comprises a web (1-2) and foot limbs (1-1) arranged on both sides of the web (1-2), wherein the foot limbs (1-1) are below the web (1-2), the angle between the foot limbs (1-1) and the web (1-2) is 90° to 135°, and the length of the foot limbs (1-1) is 10 to 20 mm; The steel web (2) is composed of continuously bent steel bars, and its inclination is consistent with the inclination of the foot (1-1). Each wave crest of the steel web (2) is welded to the foot (1-1).

2. The thin-walled upper flange truss according to claim 1, characterized in that: The lower edge of the foot (1-1) forms a gap at a position corresponding to the trough of the steel bar web.

3. The thin-walled upper flange truss according to claim 1, characterized in that: The steel web (2) is located on the inner side or outer side of the upper flange foot (1-1).

4. The thin-walled upper flange truss according to claim 1, characterized in that: The upper flange (1) is provided with a reinforcement pattern on its surface, wherein the reinforcement pattern is at least one of a transverse corrugated rib, a longitudinal reinforcement rib, or an oblique indentation.

5. The thin-walled upper flange truss according to claim 1, characterized in that: The steel bar web (2) is bent at the wave crest to form a horizontal platform.

6. The thin-walled upper flange truss according to claim 1, characterized in that: The steel web (2) is bent outwards at the wave trough to form an outward-facing "X" shape.

7. The thin-walled upper flange truss according to claim 1, characterized in that: A thin steel plate (4) is welded at the trough node of the steel web (2), and the thickness of the steel plate is 0.5-1.5 mm.

8. The thin-walled upper flange truss according to claim 1, characterized in that: A lower flange steel (3) with a diameter of 6 to 12 mm is welded to the trough of the steel web (2), and the lower flange steel (3) is parallel to the upper flange (1).

9. The thin-walled upper flange truss according to claim 8, characterized in that: The lower flange steel (3) is double-layered, the upper lower flange steel (3-1) is steel bars, and the lower lower flange steel (3-2) is steel bars or flat steel.

10. The thin-walled upper flange truss according to claim 9, characterized in that: The upper lower flange steel (3-1) is located inside or outside the steel web (2), and the lower lower flange steel (3-2) is located inside or outside the steel web (2) or below or above the trough.

11. A thin-walled upper flange truss according to claim 1, 7 or 8, characterized in that: The welding adopts the resistance welding process.

12. The thin-walled upper flange truss according to claim 1, characterized in that: The trough of the steel web (2) is connected to a concrete bottom plate (5).

13. The thin-walled upper flange truss according to claim 12, characterized in that: The concrete base plate (5) is made of C35-C60 concrete, and orthogonally distributed transverse steel bars (6) and longitudinal steel bars (8) are provided in the concrete base plate (5).

14. The thin-walled upper flange truss according to claim 13, characterized in that: The longitudinal steel bars (8) are prestressed steel bars.

15. The thin-walled upper flange truss according to claim 12, characterized in that: The concrete base plate (5) is fiber reinforced concrete with a plate thickness of 10-25 mm or concrete with a plate thickness of 10-25 mm and a welded steel mesh with a diameter of 2-5 mm.

16. The thin-walled upper flange truss according to claim 1, characterized in that: The trough of the steel web (2) is connected to a concrete composite beam (7), and longitudinal stress reinforcement (10) and stirrups (9) are arranged in the concrete composite beam (7). The diameter of the longitudinal stress reinforcement (10) is 12-25 mm, the spacing of the stirrups (9) is 50-250 mm, and the thickness of the concrete composite beam (7) is 80 mm-150 mm.

17. A method for manufacturing a thin-walled upper flange truss, characterized in that The following steps are involved: S1. Steel Strip Straightening: A three-roll straightening machine is used to straighten cold-rolled steel strip with a thickness of 0.8-3mm at a straightening speed of 2-5m / min. The flatness error after straightening is ≤1mm / m. S2. Synchronous Forming: The straightened steel strip is fed into the roll forming machine, while rebar with a diameter of 6-12 mm is fed into the synchronous bending device. The speed of the roll forming rollers is synchronized with the rebar bending rhythm. S3. Positioning and clamping: A pneumatic clamp is provided on the continuous production line to position the formed upper flange (1) and the bent steel web (2) at the node with a positioning accuracy of ±0.5mm; S4. Automatic welding: Use a multi-electrode resistance welding machine for wave node welding, with a welding pressure of 200-400N, an electrode travel speed of 1-3m / min, and a welding temperature controlled at 70%-85% of the steel melting point.

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