Prestressed prefabricated superposed beam
By designing prestressed precast composite beams, and utilizing a combination of thin concrete slabs and steel trusses, the problems of heavy self-weight, frequent steel bar collisions, and poor seismic resistance of existing precast beams have been solved, achieving lightweight, standardized production and efficient installation.
Patent Information
- Application Number
- CN202422052785.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-22
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2034-08-22
AI Technical Summary
Existing prefabricated beams are heavy, have high transportation costs, are prone to steel bar collisions, have low steel bar strength utilization, and poor seismic performance. In addition, steel pipe trusses are difficult to install, have weak rigidity, and are not safe enough.
Prestressed precast composite beams are adopted, forming a composite truss through the combination of thin concrete slabs, steel web members, steel top chords, longitudinal reinforcing bars and stirrups. The steel web members and top chord channel steel are connected, reducing on-site steel reinforcement processing, increasing the stiffness and strength of the components, and using prestressed steel strands to replace ordinary steel bars.
It achieves lightweight and standardized production, reduces on-site steel reinforcement processing, improves the seismic performance and stiffness of components, simplifies the installation process, and reduces self-weight and transportation costs.
Smart Images
Figure CN223482113U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of engineering technology, specifically a prestressed precast composite beam that can be widely used in various engineering projects. Background Technology
[0002] Existing prefabricated beam technologies mostly employ ordinary concrete composite beams, with the precast concrete portion comprising the majority and the composite portion located in the compression zone, using ordinary steel reinforcement. These existing composite beams are very heavy, resulting in high transportation costs and demanding requirements for on-site hoisting equipment. Furthermore, the steel reinforcement is entirely prefabricated within the composite beam and must be anchored to columns, beams, or shear walls, leading to numerous intersections and a high risk of steel reinforcement collisions. Moreover, the use of ordinary steel reinforcement results in low strength utilization, while prestressed steel reinforcement fails to meet seismic requirements. Existing technologies also utilize prestressed composite beams with steel pipe trusses, featuring thinner base plates. However, the upper flange of the steel pipe truss is grouted before installation, limiting the size of the steel pipes; otherwise, the truss's weight would be too great, making installation within the reinforcement cage difficult. This also weakens the beam's inherent stiffness, resulting in larger support spacing. Additionally, the connection between the upper flange of the steel pipe truss and the reinforcing web members is limited to a single weld point, leading to significant loads on the beam and compromising the structural safety. Utility Model Content
[0003] Therefore, this utility model proposes a prestressed precast composite beam to solve the problems mentioned in the background art.
[0004] To achieve the above objectives, this utility model discloses a prestressed precast composite beam, comprising: a thin concrete slab, steel web members, a steel top chord, longitudinal reinforcing bars, stirrups, and longitudinal reinforcing bars in the cast-in-place layer. Multiple longitudinal reinforcing bars are provided within the thin concrete slab; the bottom of the stirrups is anchored within the thin concrete slab; the steel web members are continuously bent steel; the steel top chord is a channel steel; the steel top chord and the crests of the steel web members are fixedly connected together to form a truss component; the troughs of the steel web members in the truss component are anchored within the thin concrete slab.
[0005] In this invention, the upper chord channel steel and steel web members form a single unit. A composite truss is formed by anchoring a precast concrete slab to the steel web truss. The concrete slab serves as the lower chord, the channel steel as the upper chord, and continuously bent flat steel or channel steel as the web members. The steel web members and upper chord channel steel are pre-assembled to form a finished truss component. This finished truss component reinforces the thin concrete base slab, ensuring its strength and rigidity. During the binding of the stirrup reinforcement cage, the finished truss component is tied together with the stirrups. The stirrups, longitudinal reinforcing bars, and truss are fixed together through the concrete base slab, forming the beam's reinforcing steel skeleton. The longitudinal reinforcing bars can serve as both the reinforcing bars for the precast components and the reinforcing bars in the composite structure. The amount of on-site steel reinforcement is significantly reduced, allowing for complete workshop processing. The truss reinforcement enhances the rigidity of the concrete base slab, enabling the precast beams to have thin, lightweight concrete slabs, simple manufacturing processes, and easy standardization for industrial production.
[0006] Furthermore, as a preferred embodiment, the steel web member is a flat steel bar, and longitudinal concave and convex ribs are pressed into the web portion; the steel upper chord is a channel steel bar.
[0007] Furthermore, as a preferred embodiment, the steel web member is a channel steel, and the channel steel has flange cuts or slits at the bends of the crests and troughs; the steel top chord is a channel steel.
[0008] Furthermore, as a preferred embodiment, the flanges or webs of the upper chord channel steel are indented or have ribs.
[0009] Furthermore, as a preferred embodiment, the upper chord of the steel channel has a small hole in the flange, through which a short steel bar or bolt passes.
[0010] Furthermore, as a preferred embodiment, the small hole is located at the crest of the steel web member.
[0011] Furthermore, as a preferred embodiment, the steel web member has a straight section at the crest, with a length of 30mm to 100mm.
[0012] Furthermore, as a preferred embodiment, the opening of the upper chord channel steel faces upward.
[0013] Furthermore, as a preferred embodiment, the width of the upper chord channel steel is smaller than that of the web channel steel.
[0014] Furthermore, as a preferred embodiment, concrete, mortar, or gypsum is poured into the upper chord channel steel.
[0015] Furthermore, as a preferred embodiment, steel bars are laid inside the upper chord of the steel.
[0016] Furthermore, as a preferred embodiment, prestressed steel bars are laid inside the upper chord of the steel.
[0017] Furthermore, preferably, the longitudinal reinforcing bars are located below the transverse short bars or bolts.
[0018] Furthermore, as a preferred embodiment, the stirrup is a welded closed stirrup.
[0019] Furthermore, as a preferred embodiment, the longitudinal reinforcing bars are prestressed steel strands or a combination of prestressed steel strands and ordinary reinforcing bars.
[0020] This utility model, employing the above-mentioned technology, offers the following advantages compared to existing technologies: The device of this utility model combines a thin concrete slab, steel web members, a steel top chord, stirrups, and longitudinal reinforcing bars to form a novel prestressed concrete precast composite beam. Its characteristics include less precast concrete, a thinner bottom slab, and the longitudinal reinforcing bars being partially precast within the precast layer. The bottom slab is reinforced using a channel steel truss, significantly reducing its thickness. This results in lighter precast components, with the reinforcing bars essentially tied within the components. With some reinforcing bars within the precast layer, the greatest common divisor of the longitudinal reinforcing bars at the bottom of the beam can be used, achieving standardization of the precast components and facilitating factory production. The remaining ordinary reinforcing bars are laid on-site, facilitating bar avoidance and promoting the formation of ductile beam-column joints, thus enhancing the structure's seismic resistance. The use of channel steel as the top chord makes component installation more convenient. Using channel steel can more effectively improve the stiffness and strength of the precast components. Concrete can also be poured onto the channel steel, cast together with the bottom slab, further increasing the component's stiffness.
[0021] Using continuously bent flat steel as web members, with longitudinal concave and convex ribs pressed into the web, increases the radius of gyration of the flat steel and reduces its slenderness ratio, thus maximizing the strength of the steel. The flat steel retains its planar appearance at the crests and troughs, making it easy to bend without damaging the steel. Flat steel is easier to machine and can be readily processed mechanically. Its wider width allows for single-row web members, forming a single-piece truss, which is more stable and saves labor and materials. Flat steel and upper chord channel steel are easier to connect and industrialize; both are wide and flat, providing a larger contact surface and more reliable connections.
[0022] Using channel steel as the web members in continuous bending results in a larger radius of gyration and greater stability for the same cross-sectional area, along with a smaller slenderness ratio, which better leverages the strength advantages of steel. Channel steel is easier to mechanically form than steel pipes, facilitating mechanized processing. The wider channel steel allows for single-row web members, forming a single-piece truss, which is more stable and saves labor and materials. The web members of the channel steel are easier to connect and industrially produce with the top chord channel steel; both are wide and flat, providing a larger contact surface and more reliable connections.
[0023] A straight section at the crest increases the connection surface between the steel top chord and the steel web members. The connection can be welded, bolted, or riveted, facilitating subsequent factory processing. The straight section is controlled to be 30-100mm, ensuring sufficient space for connection operations and guaranteeing that the extension of the web member's centroidal line intersects the bottom chord. This further facilitates the formation of an ideal truss model.
[0024] The top chord of the channel steel allows for the filling of mortar or other materials within the channel steel, into which reinforcing bars or prestressed steel bars can be placed. This helps increase the strength and stiffness of the component while reducing the amount of steel used.
[0025] Welded closed stirrups are used, which makes the components more conducive to factory processing and improves the shear resistance of the beam.
[0026] Prestressed steel strands are used for the longitudinal reinforcing bars in the precast section, and pre-tensioned prestressing is used instead of ordinary steel bars, which greatly saves steel consumption. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the structure of a prestressed precast composite beam;
[0028] Figure 2 This is a schematic diagram of the structural elevation of a prestressed precast composite beam;
[0029] Figure 3 This is a perspective view of the structural steel frame of a prestressed precast composite beam.
[0030] Figure 4 This is a schematic cross-sectional view of a prestressed precast composite beam.
[0031] Figure 5 This is a schematic cross-sectional view of a prestressed precast composite beam.
[0032] Figure 6 This is a schematic diagram of the cross-section of a prestressed precast composite beam in the form of a flat steel truss structure.
[0033] Figure 7 This is a schematic diagram of a flat steel pressing structure for a prestressed precast composite beam;
[0034] Figure 8 This is a schematic diagram of the cross-section of a prestressed precast composite beam in the form of a channel steel truss structure.
[0035] In the diagram: 1. Concrete slab; 2. Steel web members; 3. Steel top chord; 4. Longitudinal reinforcing bars; 5. Stirrups; 6. Longitudinal reinforcing bars of cast-in-place layer; 8. Small holes; 9. Transverse short reinforcing bars or bolts; 10. Longitudinal reinforcing bars. Detailed Implementation
[0036] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0037] Example: Please refer to the appendix Figure 1-8 This utility model provides a technical solution: a thin concrete slab, steel web members, a steel top chord, longitudinal reinforcing bars, stirrups, and longitudinal reinforcing bars in the cast-in-place layer. Multiple longitudinal reinforcing bars are provided within the thin concrete slab; the bottom of the stirrups is anchored within the thin concrete slab; the steel web members are continuously bent from steel bars, steel pipes, channel steel, or flat steel; the steel top chord is a channel steel or steel bar; the steel top chord is reliably connected to the crests of the steel web members to form a truss component; the troughs of the steel web members in the truss component are anchored within the thin concrete slab.
[0038] In this embodiment, the web members are made of flat steel, and the top chord is made of channel steel. These two are combined, and longitudinal concave and convex ribs are pressed into the web portion. This increases the radius of gyration of the flat steel and reduces its slenderness ratio, thus maximizing the strength of the steel. The flat steel maintains its planar shape at the crests and troughs, making it easy to bend without damaging the steel. Flat steel is easier to mechanically form and more readily achievable through mechanized processing. The larger width of the flat steel allows for a single row of web members, forming a single-piece truss. This results in a more stable truss, saving labor and materials. The flat steel and the top chord channel steel are easier to connect and industrialize; both are wide and flat, providing a larger contact surface and a more reliable connection.
[0039] In this embodiment, channel steel is used as the web members and the top chord. The combination of the two, with continuous bending of the web members, results in a larger and more stable radius of gyration and a smaller slenderness ratio for the same cross-sectional area, thus better leveraging the strength advantages of steel. Channel steel is easier to mechanically form than steel pipe, making it easier to achieve mechanized processing. The wider channel steel allows for a single row of web members, forming a single-piece truss, which is more stable and saves labor and materials. The web members and the top chord of the channel steel are easier to connect and industrially produce; both are wide and flat, resulting in a larger contact surface and a more reliable connection.
[0040] In this embodiment, the upper chord of the channel steel faces upwards, which is beneficial for fabrication. With the channel steel opening facing upwards, the web members and upper chord can be prefabricated in the factory to form a precast steel truss. It is then installed onto the concrete base slab, allowing the concrete inside the channel steel and the base slab concrete to be poured simultaneously. The precast steel truss is lighter, making installation and positioning easier for workers.
[0041] In this embodiment, the cold-pressed indentations and patterns on the web plate or flange of the channel steel web member or the upper chord of the channel steel are beneficial to enhancing the stiffness and strength of the flange, and also to enhancing the bond strength between the channel steel and the concrete.
[0042] In this embodiment, small holes are provided on the flange of the upper chord channel steel, and short reinforcing bars or bolts are passed through the holes. Since the connection between the upper chord of the channel steel and the concrete within the channel steel is relatively weak, transverse reinforcing bars or bolts are used for fixation. These transverse reinforcing bars and bolts effectively increase the shear strength of the channel steel and the concrete. Simultaneously, the transverse bolts can prevent the channel steel from deforming outwards, further ensuring the bond between the channel steel and the concrete, and guaranteeing that the upper chord channel steel and the concrete within the channel steel work together. The longitudinal reinforcing bars within the channel steel are located below the transverse short reinforcing bars or bolts, which enhances the bond strength between the longitudinal reinforcing bars and the surrounding concrete.
[0043] In this embodiment, a straight section at the crest increases the connection surface between the steel upper chord and the steel web members. The connection can be welded, bolted, or riveted, facilitating subsequent factory processing. The straight section is controlled to be 30-100mm, ensuring sufficient space for connection operations and guaranteeing that the extension of the web member's centroidal line intersects the lower chord. This is more conducive to forming an ideal truss model.
[0044] In this embodiment, the width of the upper chord of the channel steel is smaller than the width of the web member of the channel steel, which facilitates the direct welding of the flange of the web member of the channel steel to the flange of the upper chord of the channel steel, resulting in greater connection strength, simpler stress distribution, and easier manufacturing.
[0045] In this embodiment, the use of a channel steel top chord facilitates the filling of the channel steel with mortar or other fillers, and reinforcing bars or prestressed reinforcing bars can be placed inside the filler. This helps increase the strength and stiffness of the component while reducing the amount of steel used.
[0046] In this embodiment, welded closed stirrups are selected, which makes the component more conducive to factory processing and improves the shear resistance of the beam. After the stirrups are welded closed, their shape is more stable, forming a closed frame. Compared with ordinary stirrups, welded closed stirrups are easier to fix with limiting clips, eliminating the need for wire binding, and saving materials and labor in component processing. Welded closed stirrups have better mechanical properties than open stirrups and reduce mutual anchoring hooks, saving the amount of steel reinforcement used.
[0047] The welded closed hoops and precast longitudinal reinforcing bars are made of prestressed steel strands, using pre-tensioned prestressing instead of ordinary steel bars, which greatly saves steel consumption. Prestressed steel strands are also more flexible, making it easier to avoid interference with other reinforcing bars during installation.
[0048] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A prestressed precast composite beam, characterized in that, It includes: a thin concrete slab (1), steel web members (2), steel top chord (3), and stirrups (5). The thin concrete slab (1) is provided with multiple longitudinal reinforcing bars (4); the bottom of the stirrups (5) is anchored in the thin concrete slab (1); the steel web members (2) are formed by continuous bending of steel; the steel top chord (3) is a channel steel; the steel top chord (3) and the steel web members (2) are fixedly connected together to form a truss component (7); the trough of the steel web members (2) of the truss component (7) is anchored in the thin concrete slab (1).
2. The prestressed precast composite beam according to claim 1, characterized in that: The steel web member (2) is a flat steel with longitudinal concave and convex ribs pressed on the web.
3. A prestressed precast composite beam according to claim 1, characterized in that: The steel web member (2) is a channel steel, and the flange of the channel steel is cut or slit at the bends of the crests and troughs.
4. A prestressed precast composite beam according to claim 1, characterized in that: The upper chord (3) of the steel channel has engravings or ribs on its flanges or webs.
5. A prestressed precast composite beam according to claim 1, characterized in that: The upper chord (3) of the steel has a small hole (8) on its channel steel flange, through which a short steel bar or bolt (9) passes.
6. A prestressed precast composite beam according to claim 5, characterized in that: The small hole (8) is located at the crest of the steel web member (2).
7. A prestressed precast composite beam according to claim 1, characterized in that: The steel web member (2) has a straight section at the crest, with a length of 30mm to 100mm.
8. A prestressed precast composite beam according to claim 1, characterized in that: The opening of the upper chord (3) of the steel channel is facing upward.
9. A prestressed precast composite beam according to claim 3 or 8, characterized in that, The width of the channel steel of the upper steel chord (3) is smaller than the width of the channel steel of the web member (2).
10. A prestressed precast composite beam according to claim 1, characterized in that: Concrete, mortar, or gypsum is poured into the channel steel of the upper steel chord (3).
11. A prestressed precast composite beam according to claim 5, characterized in that: The upper steel chord (3) is filled with longitudinal steel bars (10).
12. A prestressed precast composite beam according to claim 11, characterized in that: The longitudinal steel bar (10) is a prestressed steel bar.
13. The prestressed precast composite beam according to claim 11, characterized in that, The longitudinal steel bars (10) laid in the upper steel chord (3) are located below the short steel bars or bolts (9) that pass through the small hole (8), and the small hole (8) is on the channel steel flange of the upper steel chord (3).
14. A prestressed precast composite beam according to claim 1, characterized in that: The stirrup (5) is a welded closed stirrup.
15. A prestressed precast composite beam according to claim 1, characterized in that: The longitudinal reinforcing bars (4) are prestressed steel strands or a combination of prestressed steel strands and ordinary reinforcing bars.