Prestressed concrete composite floor

Abstract

This utility model discloses a prestressed concrete composite floor slab, comprising a reinforced concrete slab body cast in one piece using the pre-tensioning prestressing method. A thinned section is formed at the upper part of the slab end connecting to the composite beam, serving as an interlocking space for the subsequent filling of the composite beam's concrete. Various types of reinforcing bars extend beyond the slab edge within the reinforced concrete slab body, forming a dense reinforcing mesh in the connection area with adjacent components. The thinned section creates an "interlocking space" for the on-site casting joints, allowing the composite layer concrete of the composite beam to flow more smoothly and wrap around the slab edge reinforcing bars, resulting in a denser filling and improved joint integrity and shear resistance. Furthermore, the coordinated extension of various types of reinforcing bars to form a "reinforcing mesh" increases the contact surface and mechanical interlocking effect between the precast slab and the subsequent concrete, enhancing interfacial bond strength, shear resistance, and load transfer efficiency.

Description

Technical Field

[0001] This utility model relates to the technical field of prefabricated buildings and precast building components, and in particular to a prestressed concrete composite floor slab. Background Technology

[0002] In prefabricated concrete building structures, the connection details between precast floor slabs (including prestressed hollow slabs, double-T slabs, and other precast slab types) and precast beams (or composite beams) are a core element determining the overall performance of the building structure. Their quality directly affects several key indicators such as structural integrity, seismic performance, and construction efficiency. However, the traditional connection methods commonly used in current engineering practice present numerous technical challenges that urgently need to be addressed. 1. Weak bond performance and insufficient integrity at slab-beam joints: Current practices typically involve simply placing precast slabs on beams or beam trunnions, relying solely on the limited reinforcement extending from the slab ends (in most cases, only negative moment reinforcement) to connect with the post-cast concrete of the beam. This connection method results in a severely insufficient bond contact area, making the interface region a weak point in the structure. It not only fails to meet shear resistance requirements but also cannot effectively transfer bending moments, ultimately significantly weakening the overall stiffness of the structure.

[0003] 2. The prestressing effect is not fully utilized: In the application of precast prestressed slabs, the prestressing tendons are usually cut off at the ends of the slab or simply anchored. This construction method makes it impossible for the strength advantage of the prestressing material to be effectively extended to the joint area, resulting in a serious waste of valuable prestressing resources.

[0004] Although various improvement schemes have been proposed in the engineering field (such as setting shear keyways, adding U-shaped reinforcing bars, and adopting wet connection technology), these technical measures generally suffer from inherent defects such as high structural complexity, cumbersome construction procedures, increased economic costs, or failure to effectively utilize the advantages of prestressing. Therefore, developing a high-performance connection structure that combines structural rationality, ease of construction, and economy, while fully leveraging the performance advantages of precast components, has become a key issue that urgently needs to be addressed in the development of prefabricated building technology. Summary of the Invention

[0005] To address the aforementioned problems, this utility model aims to provide a prestressed concrete composite floor slab to solve many issues existing in precast floor slabs. The thickness reduction section creates an "interlocking space" for the on-site casting joints. This is not merely a change in size, but rather allows the composite layer concrete of the composite beam to flow more smoothly and wrap around the reinforcing bars extending from the slab edge, resulting in a denser filling and significantly improving the integrity and shear resistance of the joint. Furthermore, the coordinated extension of various types of reinforcing bars within the reinforced concrete slab forms a dense "reinforcing mesh," greatly increasing the contact surface and mechanical interlocking effect between the precast slab and the post-cast concrete (beam composite layer, post-cast strip between slabs), significantly improving the interface bond strength, shear resistance, and load transfer efficiency.

[0006] To achieve the above objectives, this utility model discloses a prestressed concrete composite floor slab, the key features of which are: a reinforced concrete floor slab body formed by prestressing and one-time casting using the pre-tensioning method; the upper part of the reinforced concrete floor slab body is empty at the slab end connecting the composite beam to form a thickness reduction section; the thickness reduction section serves as an interlocking space for the subsequent filling of the composite beam with concrete; wherein, various types of steel bars arranged in the reinforced concrete floor slab body extend outward from the slab edge, thereby forming a dense steel mesh in the connection area with adjacent components.

[0007] Furthermore, the various types of reinforcing bars include longitudinal reinforcing bars and transverse distribution bars; the longitudinal reinforcing bars extend longitudinally beyond the edge of the slab and can act on the beam composite layer; the transverse distribution bars extend transversely beyond the edge of the slab and can act on the post-cast strip between slabs or the beam composite layer.

[0008] Furthermore, the longitudinal reinforcing bars consist of top longitudinal bars and bottom longitudinal bars, with upper and lower transverse distribution bars arranged between them.

[0009] Furthermore, the top longitudinal reinforcement of the slab is made of negative moment reinforcement, and the bottom longitudinal reinforcement is made of prestressed reinforcement.

[0010] Furthermore, the thickness of the reinforced concrete floor slab in the non-thickness reduction section is twice the thickness of the thickness reduction section.

[0011] Furthermore, the length of the thickness reduction section is 200mm-300mm.

[0012] Furthermore, the interface between the thinned section and the post-cast concrete of the composite beam is set as a rough surface.

[0013] Furthermore, a keyway is provided at the end of the reinforced concrete floor slab where adjacent components are connected.

[0014] Compared with the prior art, the significant advantages of this utility model are: (1) Optimized design of thickness reduction section: Through the thickness reduction section at the end of the slab, a depth-optimized "interlocking space" is created at the junction of the precast slab and the beam composite layer. This special structure allows the concrete of the beam composite layer to more completely and tightly wrap the steel bars protruding from the end of the slab, especially the wrapping effect on the longitudinal steel bars at the top of the slab. This design not only significantly increases the effective anchorage length of the steel bars, but also significantly expands the bond contact area between the steel bars and the concrete, thereby achieving a comprehensive improvement in the joint shear bearing capacity, bending stiffness and negative bending moment transfer capacity in terms of mechanical properties, making the structural connection more reliable and stable; (2) Coordinated extension of multiple types of reinforcing bars: The innovative design scheme adopts a method in which all key reinforcing bars (including transverse distribution bars, top longitudinal bars and bottom longitudinal bars) extend simultaneously and participate in anchorage. Compared with the traditional approach of only extending the main load-bearing bars, this multi-bar coordinated working mechanism has achieved performance breakthroughs in multiple dimensions: significantly enhanced bond strength between precast slab and post-cast concrete (including joint areas and post-cast strips), greatly improved interface shear resistance, optimized load transfer path and efficiency, and made the overall structural performance far exceed conventional design standards; (3) Application of prestressed tendons: The core innovation of this technology is to extend and anchor prestressed tendons as the bottom longitudinal reinforcement of the slab in the beam joint area. The prestressing effect not only acts on the slab itself, but its residual stress also plays multiple important roles in the joint area: effectively restraining concrete deformation, significantly inhibiting crack propagation, and improving the overall stiffness and crack resistance of the joint area. This design fully explores and utilizes the full life cycle value of prestressed steel bars, and maximizes the utilization of material properties; (4) Rigid / Semi-rigid Connection: By fully anchoring the key steel bars at the end of the slab into the composite layer of the beam, a high-performance connection with near-rigid or semi-rigidity is formed between the precast slab and the beam. This connection method brings a qualitative leap in structural performance: it greatly improves the integrity and continuity of the floor slab, significantly enhances the seismic performance of the structure, effectively improves the dynamic response characteristics of the structure, and provides a higher level of protection for the safety of the building structure; (5) Adopting a fully prefabricated structure: The composite floor slab is made of fully prefabricated prestressed concrete slabs without overlapping layers. This prefabrication method realizes a high degree of factory production, which not only ensures stable and reliable component quality, but also greatly improves production efficiency and can significantly shorten the construction cycle. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the external structure of the reinforced concrete floor slab in Example 1 (I); Figure 2 This is a schematic diagram of the external structure of the reinforced concrete floor slab in Example 1 (II); Figure 3 This is a schematic diagram of the internal structure of the reinforced concrete floor slab in Example 1 (I); Figure 4 This is a schematic diagram (II) of the internal structure of the reinforced concrete floor slab in Example 1. Figure 5 This is a construction state diagram of the reinforced concrete floor slab in Example 1; The labels in the drawing are: 1-reinforced concrete slab body, 2-thickness reduction section, 3-top longitudinal reinforcement, 4-bottom longitudinal reinforcement, 5-upper layer transverse distribution reinforcement, 6-lower layer transverse distribution reinforcement, 7-keyway. Detailed Implementation

[0017] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0018] In the description of this utility model, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, in the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0019] Figures 1 to 5 The first embodiment of this utility model is disclosed: a prestressed concrete composite floor slab, including a reinforced concrete floor slab body 1 formed by prestressing in one-time casting using the pre-tensioning method; the upper part of the reinforced concrete floor slab body 1 is empty at the slab end connecting the composite beam to form a thickness reduction section 2; the thickness reduction section 2 serves as an interlocking space for the subsequent pouring of concrete for the composite beam; wherein, various types of steel bars arranged in the reinforced concrete floor slab body 1 extend outward from the edge of the slab, thereby forming a dense steel mesh in the connection area with adjacent components.

[0020] In this embodiment, the prestressed concrete slab body 1 is formed by pre-tensioning and one-time casting, which ensures the overall strength and stability of the slab. The resulting thinning section 2 is the ingenious part of the entire structure. When the post-cast concrete of the composite beam fills into this interlocking space, it tightly combines with the various types of reinforcing bars extending outward from the edge of the slab, forming a strong anchoring force.

[0021] Please see Figure 3 and Figure 4 In specific implementation, the various types of reinforcing bars include longitudinal reinforcing bars and transverse distribution bars. The longitudinal reinforcing bars extend longitudinally beyond the slab edge and can act on the beam composite layer; the transverse distribution bars extend transversely beyond the slab edge and can act on the post-cast strip between slabs or the beam composite layer. This design allows the beam composite layer and the post-cast strip between slabs to form a cohesive whole with the reinforced concrete floor slab body 1 after construction, greatly enhancing the overall structural integrity. The longitudinal reinforcing bars acting on the beam composite layer can effectively transfer the load borne by the floor slab to the beam, ensuring the mechanical performance of the structure. The transverse distribution bars acting on the post-cast strip between slabs or the beam composite layer not only strengthen the connection between floor slabs and between the floor slab and the beam, but also better resist transverse forces, improving the stability of the structure.

[0022] like Figure 3 and Figure 4 As shown, the longitudinal reinforcement consists of top longitudinal bars 3 and bottom longitudinal bars 4, with upper transverse distribution bars 5 and lower transverse distribution bars 6 arranged between them. The top longitudinal bars 3 are negative moment bars, which play a key role in the connection with the beam overlay. During actual stress, the negative moment bars can effectively resist the negative bending moment generated at the beam end, rationally transferring the force to the entire structure and enhancing the bending resistance of the structure. The bottom longitudinal bars 4 are prestressed bars and extend and anchored in the beam joint area. The presence of the prestressed bars gives the floor slab a certain prestress before bearing the load. When the floor slab bears external loads, the prestress can offset part of the tensile stress, thereby delaying the generation and development of cracks and improving the crack resistance and durability of the floor slab. The upper transverse distribution bars 5 and lower transverse distribution bars 6 extend transversely beyond the edge of the slab. They intertwine with the longitudinal reinforcement to form a strong steel reinforcement skeleton, enhancing the overall stiffness of the reinforced concrete floor slab body 1. The extended sections of these distributed reinforcement bars further increase the bond between the reinforcement and the concrete when they are combined with the post-cast concrete, enabling the post-cast concrete to work better with the composite floor slab.

[0023] During construction, the thickness of the reinforced concrete slab body 1 in the non-thickness-reduced section 2 is twice that of the thickness-reduced section 2. This reasonable thickness design ensures the load-bearing capacity of the slab in the main structure area and facilitates the filling of post-cast concrete and the anchoring of reinforcing bars in the thickness-reduced section 2. The length of the thickness-reduced section 2 is 200mm-300mm. This size range has been verified in construction to meet the requirements of the composite beam's composite layer concrete flowing in and wrapping the extended reinforcing bars at the edge of the slab, without affecting the overall structural performance of the slab due to excessive length.

[0024] The interface between the thinned section 2 and the post-cast concrete of the composite beam is roughened. This roughened surface design significantly increases the friction and adhesion of the interface, allowing the post-cast concrete and the precast floor slab to bond better together, thus improving the integrity and shear resistance of the joint. Simultaneously, a keyway 7 (see reference) is provided at the end of the reinforced concrete floor slab 1 where it connects to adjacent components. Figure 1 The presence of keyway 7 further enhances the connection strength and integrity between the precast slab and adjacent components, making the entire building structure more stable and reliable.

[0025] In summary, this technology has significant innovative and practical value in the field of prefabricated buildings. It addresses numerous problems existing in the construction of connection nodes for prefabricated floor slabs, proposing a systematic and efficient solution that optimizes and innovates traditional technologies in multiple aspects. Optimized design of thickness reduction section 2: Through thickness reduction section 2 at the end of the slab, a depth-optimized "interlocking space" is created at the junction of the precast slab and the beam composite layer. This special structure allows the concrete of the beam composite layer to more completely and tightly wrap the steel bars extending from the slab end, especially the longitudinal steel bars at the top of the slab. This design not only significantly increases the effective anchorage length of the steel bars, but also significantly expands the bond contact area between the steel bars and the concrete, thereby achieving a comprehensive improvement in the joint shear capacity, flexural stiffness, and negative bending moment transfer capacity in terms of mechanical properties, making the structural connection more reliable and stable. Multiple types of reinforcing bars extend in tandem: An innovative design scheme is adopted in which all key reinforcing bars (including transverse distribution bars, top longitudinal bars 3 and bottom longitudinal bars 4) extend simultaneously and participate in anchorage in a coordinated manner. Compared with the traditional approach of only extending the main load-bearing bars, this multi-reinforcement collaborative working mechanism achieves performance breakthroughs in multiple dimensions: significantly enhances the bond strength between the precast slab and the post-cast concrete (including joint areas and post-cast strips), greatly improves the interface shear resistance, optimizes the load transfer path and efficiency, and makes the overall structural performance far exceed conventional design standards; Prestressed tendon application technology: The core innovation of this technology lies in extending and anchoring prestressed tendons as bottom longitudinal reinforcement in the beam joint area. The prestressing effect not only acts on the slab itself, but its residual stress also plays multiple important roles in the joint area: effectively restraining concrete deformation, significantly inhibiting crack propagation, and improving the overall stiffness and crack resistance of the joint area. This design fully explores and utilizes the full life-cycle value of prestressed steel bars, maximizing the utilization of material properties. Rigid / Semi-rigid Connection: By fully anchoring the key reinforcing bars at the slab ends deep into the beam composite layer, a near-rigid or semi-rigid high-performance connection is formed between the precast slab and the beam. This connection method brings a qualitative leap in structural performance: significantly improving the integrity and continuity of the floor slab, significantly enhancing the seismic performance of the structure, effectively improving the dynamic response characteristics of the structure, and providing a higher level of protection for the safety of building structures; The composite floor slab adopts a fully prefabricated structure: the entire composite floor slab is made of fully prefabricated prestressed concrete slabs without overlapping layers. This prefabrication method realizes a high degree of factory production, which not only ensures stable and reliable component quality, but also greatly improves production efficiency and can significantly shorten the construction cycle.

[0026] The above-disclosed embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of the present utility model. Those skilled in the art can understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present utility model are still within the scope of the utility model.

Claims

1. A prestressed concrete composite floor slab, characterized in that: The system includes a reinforced concrete floor slab body formed by prestressing and one-time casting using the pre-tensioning method; the upper part of the reinforced concrete floor slab body is empty at the slab end connecting the composite beam to form a thickness reduction section; the thickness reduction section serves as an interlocking space for the subsequent pouring of concrete for the composite beam; wherein, various types of steel bars arranged in the reinforced concrete floor slab body extend outward from the slab edge, thereby forming a dense steel mesh in the connection area with adjacent components.

2. The prestressed concrete composite floor slab according to claim 1, characterized in that: The various types of reinforcing bars include longitudinal reinforcing bars and transverse distribution bars; the longitudinal reinforcing bars extend longitudinally beyond the edge of the slab and can act on the beam composite layer; the transverse distribution bars extend transversely beyond the edge of the slab and can act on the post-cast strip between slabs or the beam composite layer.

3. The prestressed concrete composite floor slab according to claim 2, characterized in that: The longitudinal reinforcing bars consist of top longitudinal bars and bottom longitudinal bars, with upper and lower transverse distribution bars arranged between them.

4. The prestressed concrete composite floor slab according to claim 3, characterized in that: The top longitudinal reinforcement of the slab is a negative moment reinforcement, and the bottom longitudinal reinforcement is a prestressed reinforcement.

5. The prestressed concrete composite floor slab according to any one of claims 1-4, characterized in that: The thickness of the reinforced concrete floor slab in the non-thickness reduction section is twice the thickness of the thickness reduction section.

6. The prestressed concrete composite floor slab according to claim 5, characterized in that: The length of the thickness reduction section is 200mm-300mm.

7. The prestressed concrete composite floor slab according to claim 1 or 6, characterized in that: The interface between the thinned section and the post-cast concrete of the composite beam is set as a rough surface.

8. The prestressed concrete composite floor slab according to claim 1, characterized in that: A keyway is provided at the end of the reinforced concrete floor slab connecting adjacent components.

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