Prestressed laminated slab and manufacturing method and using method thereof

Abstract

The invention discloses a prestressed laminated slab as well as a manufacturing method and a using method thereof, and belongs to the technical field of constructional engineering. The prestressed laminated slab comprises a transverse pipeline, a prefabricated concrete bottom plate, reinforcing ribs, longitudinal prestressed tendons and transversely distributed steel bars, the transverse pipelines are arranged at intervals in the first direction, are partially embedded in the prefabricated concrete bottom plate and are parallel to the second direction; longitudinal prestressed tendons and transverse distributed steel bars are arranged in the prefabricated concrete bottom plate. The reinforcing ribs are arranged at intervals in the first direction, and the bottoms of the reinforcing ribs are fixed to the prefabricated concrete bottom plate. The first direction is the length direction of the precast concrete bottom plate, and the second direction is the width direction and is perpendicular to the precast concrete bottom plate. The reinforcing ribs can adopt various structures such as concrete ribs and steel pipe trusses, and light material blocks are arranged on the prefabricated concrete bottom plate and arranged in an area defined by the reinforcing ribs and the transverse pipelines. The manufacturing method comprises the following steps: cleaning a mold table, assembling the mold, distributing the reinforcements, tensioning, fixing the pipeline and the reinforcing ribs, pouring, maintaining and the like. During use, the two-way prestressed floor slab is formed through hoisting, pipeline connection, reinforcement, reinforcement penetrating, pouring, tensioning and grouting. The problems that an existing laminated slab is poor in stress performance, prone to cracking, insufficient in bonding strength and the like are solved, bidirectional prestress design, consistent bidirectional rigidity of a floor system and bidirectional force transmission performance are achieved, the integrality and crack resistance of a floor slab are improved, the self weight is reduced, the steel consumption is reduced, the construction process is simplified, and the laminated slab is suitable for large-span and heavy-load building scenes.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, specifically a prestressed composite slab that can be widely used in floor slabs of various buildings, especially suitable for large-span, heavy-load building scenarios, and can effectively improve the integrity and crack resistance of floor slabs. Background Technology

[0002] In the field of prefabricated buildings, prestressed composite slabs are widely used due to their high production efficiency and good crack resistance. Their main forms include concrete ribbed composite slabs and steel pipe truss prestressed composite slabs. The common feature of these technologies is that they all have reinforcing ribs on a precast concrete base slab, with gaps or holes reserved at the junction of the ribs and the base slab for inserting transverse reinforcing bars. During on-site construction, the precast components are first assembled into place, and then reinforcing bars are inserted through the reserved gaps in a direction perpendicular to the reinforcing ribs (i.e., transversely to the floor slab). Finally, the composite layer concrete is poured, thus forming a two-way stressed floor slab structure.

[0003] However, the aforementioned traditional technical solutions have gradually revealed the following technical bottlenecks and challenges in practical engineering applications:

[0004] 1. The contradiction between mechanical performance and durability of post-installed reinforcing bars is prominent: To meet the overall stiffness and transportation and hoisting requirements of composite slabs, precast concrete base slabs are usually quite thick, which leads to a significant increase in the thickness of the protective layer for post-installed transverse reinforcing bars. An excessively large protective layer reduces the effective lever arm of the reinforcing bars, weakens their contribution to bending resistance, and may exacerbate the risk of later cracking due to increased shrinkage stress on the concrete surface. In large-span, heavy-load floor slabs that require lightweight weight-reduction blocks, the base slab thickness is further increased, making this contradiction even more acute.

[0005] 2. Structural performance and economy need improvement: Current technologies generally use post-insertion of ordinary steel bars to achieve lateral stress. Ordinary steel bars cannot be prestressed, resulting in insufficient crack resistance at the joints of the components, making them prone to cracking. At the same time, to achieve the design load-bearing capacity, a large amount of steel bars is often required, resulting in high steel consumption and poor economic efficiency.

[0006] 3. Insufficient bond reliability at the composite surface and rib-base connection: For concrete rib composite slabs with weight-reducing blocks, the contact area (i.e., composite surface) between the precast base slab and the upper cast-in-place concrete is relatively reduced. Furthermore, if the concrete reinforcing ribs and base slab are formed through secondary casting, their interfacial bond strength may become a weak point. These factors collectively lead to unsatisfactory synergistic performance (integrity) between the precast and cast-in-place components. As the floor slab span and load increase, it may be difficult to meet higher structural bearing capacity and integrity requirements.

[0007] 4. High difficulty in controlling the processing accuracy and quality of precast components: When using a method of pre-drilling holes for reinforcing bars in concrete ribs, the positioning accuracy of the holes during factory prefabrication is easily affected by factors such as mold installation, concrete pouring, and vibration, which can easily lead to positional deviations or blockages. This not only increases the processing difficulty and defect rate but also makes the reinforcing bar insertion operation difficult on site, affecting construction efficiency and quality controllability.

[0008] Therefore, there is an urgent need for a new type of prestressed composite slab system, which aims to overcome the above-mentioned defects while maintaining the advantages of prefabrication and assembly, and achieve better stress performance, higher construction efficiency, better economy and more reliable quality control, so as to meet the needs of modern buildings for large-span, heavy-load and high-performance floor slab systems. Summary of the Invention

[0009] Therefore, this invention proposes a prestressed composite slab, its manufacturing method, and its usage method to solve the problems mentioned in the background art, such as poor stress performance, easy cracking of components, insufficient bonding strength, high processing difficulty, and low construction efficiency of existing prestressed composite slabs.

[0010] To achieve the above objectives, the present invention discloses a prestressed composite slab, characterized in that it includes transverse pipes (1), a precast concrete base slab (2), reinforcing ribs (3), longitudinal prestressing tendons (4), and transverse distributed reinforcing bars (5); the transverse pipes (1) are arranged in multiple intervals along a first direction, and are partially embedded in the precast concrete base slab (2); the transverse pipes (1) are parallel to a second direction, and their length is consistent with the width of the precast concrete base slab (2); the precast concrete base slab (2) is provided with longitudinal prestressing tendons (4) and transverse distributed reinforcing bars (5); the longitudinal... The prestressing tendons (4) are arranged parallel to the first direction and spaced apart along the second direction. The transversely distributed reinforcing bars (5) are arranged parallel to the second direction and spaced apart along the first direction. Multiple reinforcing ribs (3) are arranged parallel to the first direction and spaced apart along the second direction. The bottom of the reinforcing ribs (3) is fixedly connected to the precast concrete base plate (2). The first direction is the length direction of the precast concrete base plate (2), and the second direction is the width direction of the precast concrete base plate (2). The first direction and the second direction are perpendicular to each other, and the plane formed by the two is parallel to the surface of the precast concrete base plate (2).

[0011] Furthermore, the bottom of the transverse pipe (1) is higher than the top of the longitudinal prestressing tendon (4) and lower than the upper surface of the precast concrete base slab (2), ensuring that the protective layer thickness of the post-tensioned prestressing steel meets the design requirements, while improving the stress performance of the component. The transverse pipe (1) is made of corrugated metal pipe, which is easy to obtain and has an uneven surface, which can effectively enhance the bonding force between the post-tensioned prestressing steel, grouting material and concrete, and ensure the overall working performance of the structure. The bottom surface of the transverse pipe (1) is 5mm~20mm lower than the upper surface of the precast concrete base slab (2), and part of it is embedded in the precast concrete base slab (2). This setting can control the protective layer thickness of the post-tensioned prestressing steel within 30mm, increase the lever arm of the post-tensioned prestressing steel, improve the load-bearing capacity of the component, reduce the amount of steel used, and at the same time keep consistent with the design model parameters, reducing the workload of design verification calculation.

[0012] As a preferred embodiment, the transverse pipe (1) is arranged in multiple intervals perpendicular to the longitudinal prestressing tendons (4), with a spacing of not less than 500 mm. Appropriately increasing the spacing of the transverse pipe (1) is beneficial for component processing and reduces the number of reinforcing bars inserted; at the same time, after the spacing is increased, the material properties can be fully utilized by using post-inserted prestressing reinforcing bars to compensate for the problem of increased steel bar calculation caused by the increased spacing.

[0013] Furthermore, the reinforcing rib (3) can adopt any of the following structures to flexibly adapt to different engineering scenarios:

[0014] A) Concrete ribs, which are cast together with the precast concrete base plate (2) in one piece. The cross section is rectangular or T-shaped, with good rigidity and low cost, which can effectively improve the bending strength and rigidity of the precast concrete base plate (2).

[0015] B) Steel pipe truss, wherein the steel pipe truss uses round or flat tubes as the top chord and continuous bent steel bars as the web members, eliminating the need for secondary casting, facilitating the batch production of precast base plates, and further reducing the self-weight of the components;

[0016] C) Concrete truss composite rib, wherein the concrete truss composite rib is made of concrete or reinforced concrete as the top chord rib and bent steel bars or steel pipes as the web members, taking into account both stiffness and economy.

[0017] D) Prestressed concrete truss composite rib, wherein the upper chord of the prestressed concrete truss composite rib is an outer steel sheet structure, with prestressed steel bars and poured concrete inside, and the web members are made of bent steel bars, steel pipes or bent corrugated steel plates, which have strong load-bearing capacity and are suitable for large span and heavy load scenarios.

[0018] Furthermore, when the reinforcing rib (3) is a concrete rib, it is provided with stirrups (7) or continuously bent corrugated bars (8) inside, which can effectively improve the shear resistance between the concrete rib and the precast concrete base plate (2) and enhance the overall shear bearing capacity of the composite component. This improves the shear performance between the cast-in-place concrete and the precast component, thereby enhancing the overall shear bearing capacity of the composite component.

[0019] This invention integrates a reinforced concrete slab, lightweight material blocks (weight-reducing blocks), and transverse ducts for post-tensioned prestressed steel bars onto a single component. After the floor slab is assembled, the transverse ducts between adjacent components are connected to form a complete through-tube reinforcement system. Post-tensioned prestressed steel bars are then threaded through and tensioned, ultimately forming a bidirectional prestressed composite floor slab with reduced reinforcement. This structure enables large-span, heavy-load, and bidirectional isotropic floor slab designs, resulting in better overall integrity and crack resistance, and more uniform bidirectional force transmission. Simultaneously, the bidirectional prestressed design significantly reduces the amount of reinforcement required in the floor slab, simplifies the construction process, improves construction convenience, and effectively addresses many shortcomings of existing technologies.

[0020] Furthermore, as a preferred embodiment, the lightweight material block (6) (weight reduction block) is a steel mesh box, a lightweight membrane shell, or a foam board. Replacing concrete in areas with low stress with hollow or lightweight materials can effectively save concrete usage and reduce the structural self-weight. At the same time, the lightweight material block (6) can serve as a lateral formwork for cast-in-place concrete ribs, forming a two-way concrete ribbed floor after pouring.

[0021] Furthermore, as a preferred option, the lightweight material block (6) is cast as a single unit with the precast concrete base slab (2). Precasting the lightweight material block (6) and the precast concrete base slab (2) in the factory in advance can improve on-site installation efficiency, save construction time, and effectively avoid the problem of the lightweight material block (6) floating during the cast-in-place concrete pouring, as well as the problem of the concrete directly below the lightweight material block (6) not being dense.

[0022] Furthermore, as a preferred option, the lightweight material block (6) can also be placed on the precast concrete base plate (2) and fixed firmly to the precast concrete base plate (2), and the fixing method can be flexibly selected according to the construction requirements.

[0023] Furthermore, as a preferred embodiment, the lightweight material block (6) is placed within the area enclosed by the reinforcing rib (3) and the transverse pipe (1). The reinforcing rib (3) and the transverse pipe (1) form orthogonal gaps, and the lightweight material block (6) is placed within this area. After pouring concrete, it can form concrete ribs, ultimately constituting a two-way densely ribbed floor slab, thereby improving the overall stiffness and load-bearing capacity of the floor slab.

[0024] This invention also discloses a method for manufacturing the above-mentioned prestressed composite slab, characterized by comprising the following steps:

[0025] Step 1: Clean the mold platform to ensure that the surface is flat, free of debris and oil, so as to provide a good foundation for subsequent mold assembly and pouring;

[0026] Step 2: Assemble the molds according to the design drawings, strictly control the mold dimensions, and ensure that the mold accuracy meets the design specifications. After the molds are assembled, check the mold's firmness to prevent problems such as grout leakage and deformation during the pouring process.

[0027] Step 3: Apply release agent evenly to the inner wall of the mold, ensuring a consistent thickness to facilitate smooth demolding of subsequent components and avoid damaging the component surface;

[0028] Step 4: Arrange longitudinal prestressed tendons (4) and transverse distributed reinforcing bars (5) in the mold, strictly control the position, spacing and protective layer thickness of the reinforcing bars in accordance with the design requirements, and ensure that the reinforcing bars are arranged accurately;

[0029] Step 5: Tensioning operation is carried out on the longitudinal prestressing tendons (4). The tensioning control value meets the design standards and relevant specifications. After tensioning is completed, anchoring is carried out to prevent prestress loss.

[0030] Step 6: Fix the transverse distribution steel bars (5), transverse pipes (1) and reinforcing ribs (3) to ensure that each component is installed firmly and in the correct position. The transverse pipes (1) need to pass through the reinforcing ribs (3). After fixing, check the position accuracy again. Ensure the distance between the bottom surface of the transverse pipes and the bottom surface of the base plate to ensure the thickness of the protective layer of the transverse prestressing tendons.

[0031] Step 7: Pour concrete. During the pouring process, use a suitable vibration method to ensure that the concrete is dense and free from quality defects such as honeycomb and pitting. After pouring, level the slab surface to ensure that the slab surface is flat.

[0032] Step 8: Before the concrete sets, place the lightweight material block (6) and insert the stirrups (7) on the concrete rib (if the reinforcing rib is a concrete rib), ensuring that the lightweight material block (6) is in the correct position and is firmly fixed, and that the insertion depth of the stirrups (7) meets the design requirements;

[0033] Step 9: Perform curing work on the poured components. The curing conditions should meet the requirements of the concrete curing specifications. Select appropriate curing methods according to the ambient temperature and humidity to ensure normal strength growth of the concrete.

[0034] Step 10: After the concrete strength reaches the design requirements, the longitudinal prestressed tendons (4) are released slowly and evenly to avoid impact stress on the components. After the release is completed, the boards are removed and stored in categories. Protective measures are taken during storage to prevent damage to the components.

[0035] The present invention also discloses a method for using the above-mentioned prestressed composite slab, characterized by comprising the following steps:

[0036] Step 1: Transport the pre-fabricated prestressed composite slabs from the factory to the construction site. During transportation, take measures to secure and protect the components to prevent collisions and deformation. After arriving at the site, store them according to their component numbers. The storage area should be flat and firm to prevent the components from getting damp or damaged.

[0037] Step 2: According to the construction design requirements, lay temporary supports in the construction area. The bearing capacity, spacing and stability of the temporary supports meet the design requirements to ensure that they can withstand the self-weight of the precast components and subsequent construction loads.

[0038] Step 3: According to the component number, use hoisting equipment to hoist the prestressed composite slab to the preset installation position. The hoisting process is stable, slow and precise. After hoisting, adjust the position of the component to align the transverse pipes (1) of adjacent prestressed composite slabs to ensure smooth subsequent pipe connection.

[0039] Step 4: Use special connectors to connect and fix the aligned transverse pipes (1), and seal the connection tightly to ensure no grout leakage; at the same time, set several air leakage holes on the transverse pipes (1), and connect the air leakage holes through special pipes. The upper part of the special pipes is higher than the design height of the subsequent concrete pouring, so as to facilitate the discharge of air in the pipes during the pouring process and ensure that the grouting is dense.

[0040] Step 5: According to the design requirements, tie the slab surface reinforcement on the slab surface. The specifications, spacing and anchorage length of the reinforcement shall meet the design specifications. After tying, check the position and firmness of the reinforcement.

[0041] Step 6: Pass the transverse prestressing tendons through the transverse duct (1). The threading process should be smooth to avoid bending or damage to the transverse prestressing tendons. After threading, adjust the position of the transverse prestressing tendons to ensure that they are centered and installed in place.

[0042] Step 7: Pour the concrete for the slab surface. During the pouring process, distribute the concrete evenly and use a suitable vibration method to compact it, ensuring that the concrete is tightly bonded to the precast components and free from quality defects such as honeycomb and pitting.

[0043] Step 8: After the concrete strength of the slab reaches the design requirements, tension the transverse prestressing tendons from Step 6. The tension control values ​​shall meet the design standards and relevant specifications. After tensioning, anchor the tendons.

[0044] Step 9: According to the design requirements, grouting is carried out in the horizontal pipe (1). The grouting material meets the design requirements. The grouting process is continuous and uniform to ensure that the grouting in the pipe is dense and without gaps. After the grouting is completed, excess grouting material is cleaned up in time to ensure that the surface of the component is clean.

[0045] The order of steps 6 and 7 can be interchanged and adjusted flexibly according to on-site construction conditions and schedule requirements.

[0046] The present invention adopts the above technical solution and has the following beneficial effects compared with the prior art:

[0047] 1. This invention combines a ribbed concrete base slab, lightweight material blocks (weight-reducing blocks), and transverse pipes to form a novel composite slab, achieving a bidirectional prestressed design for the composite slab. The thickness of the concrete cover for the reinforcement in both directions is controlled within 30mm. The concrete cover for the longitudinal prestressing tendons is ensured by the prefabrication process, while the concrete cover for the transverse (post-tensioned) prestressing tendons is controlled by the position of the pre-embedded transverse pipes. Consistent with design values, this results in reduced steel reinforcement usage and a more rational component design. Simultaneously, the component processing flow is simplified, quality is easier to control, and the problems of misaligned holes and high processing difficulty in existing technologies are solved.

[0048] 2. The transverse pipe has multiple functions. It can form a complete through pipe after the concrete base slab is assembled, which is used to install post-tensioned prestressed steel bars. It can also be used as a positioning guide for reinforcing ribs and lightweight material blocks to ensure the accurate position of each component during the component processing and improve the processing quality.

[0049] 3. There is no need to separately lay and fix the lightweight material blocks and lay horizontal pipes on the installation site. When pouring concrete on site, the problems of buoyancy of the lightweight material blocks and the problem of insufficient compaction of the concrete under the lightweight material blocks can be solved simultaneously, which greatly reduces the construction process, improves construction efficiency and shortens the construction period.

[0050] 4. After the ribbed concrete base slab is assembled on site, the structure can be supported with little or no support during the assembly of precast components and the subsequent concrete pouring. Compared with the existing cast-in-place concrete floor slab with post-tensioned prestressed structure, there is no need to wait for the post-tensioned prestressing construction to be completed and the grouting to reach the strength before removing the support frame and formwork, which reduces the turnover time of the support frame and formwork, further shortens the construction period, and reduces construction costs.

[0051] 5. The use of lightweight material blocks can effectively reduce the structural self-weight, especially suitable for large-span, heavy-load floor slabs. The lightweight material blocks are arranged in a regular horizontal and vertical pattern, with transverse pipes placed between the lightweight material blocks perpendicular to the reinforcing ribs. The transverse spacing is controlled within the range of 500~1000mm, which makes the reinforcement arrangement more concentrated. Combined with the use of post-tensioned prestressed steel bars, the performance of steel materials can be fully utilized, the number of steel bars can be reduced, the amount of steel used can be greatly saved, and the difficulty of on-site reinforcement threading can be reduced.

[0052] 6. The floor slab is assembled from precast base plates and then concrete is poured to form a whole. The prestressing construction through post-tensioning generates pre-compression stress between the precast components, which effectively improves the integrity and crack resistance of the floor slab. The bidirectional prestressing design makes the structural stiffness of the floor slab more consistent in both directions, and the bidirectional structural performance is similar, which can more effectively form a bidirectional force transmission floor slab, improving the overall load-bearing capacity and service performance of the floor slab.

[0053] 7. The use of prestressing in both directions significantly reduces the amount of steel reinforcement required for the floor slab. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of a prestressed composite slab structure (steel-concrete composite truss rib).

[0055] Figure 2 This is a schematic diagram of a prestressed composite slab structure (steel-concrete composite truss rib).

[0056] Figure 3 This is a schematic diagram of a prestressed composite slab structure (concrete ribs + stirrups).

[0057] Figure 4 This is a schematic diagram of a prestressed composite slab structure (concrete ribs + bent bars).

[0058] Figure 5 This is a schematic diagram of a prestressed composite slab structure (concrete ribs + composite truss ribs + lightweight blocks).

[0059] Figure 6 This is a schematic diagram of a prestressed composite slab assembly structure;

[0060] In the diagram: 1. Horizontal pipe; 2. Precast concrete base slab; 3. Reinforcing rib; 4. Longitudinal prestressed tendon; 5. Horizontal distributed reinforcement; 6. Lightweight material block; 7. Stirrup; 8. Continuous bent corrugated reinforcement. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] Example: Please refer to the appendix. Figure 1-6 The present invention provides a technical solution: a prestressed composite slab and its manufacturing and usage methods, as detailed below:

[0063] This embodiment discloses a two-way prestressed weight-reducing prefabricated composite floor slab system, the core component of which is a prestressed composite slab. The prestressed composite slab includes a transverse pipe (1), a precast concrete base slab (2), reinforcing ribs (3), longitudinal prestressing tendons (4), transverse distribution reinforcing bars (5), and lightweight material blocks (6). The precast concrete base slab (2) is provided with pre-tensioned longitudinal prestressing tendons (4) and transverse distribution reinforcing bars (5). The precast concrete base slab (2) is provided with reinforcing ribs (3) and transverse pipes (1). The transverse pipes (1) pass through the reinforcing ribs (3) and are used to pass through the post-tensioned prestressing reinforcing bars.

[0064] In this embodiment, a reinforced concrete base slab, a lightweight material block (weight-reducing block), and a transverse pipe are integrated into a single component to form a prefabricated component for a bidirectional prestressed weight-reducing prefabricated composite slab. Its core advantage lies in overcoming many shortcomings of existing technologies, and the specific effects are as follows:

[0065] The installation site does not require separate paving and fixing of lightweight material blocks or the arrangement of horizontal pipes. During on-site concrete pouring, the issues of buoyancy of the lightweight material blocks and insufficient compaction of the concrete beneath them can be solved simultaneously, significantly reducing construction steps, improving construction efficiency, and shortening the construction period. After the ribbed concrete base slab is assembled on-site, the structure can be supported with little or no support during the assembly of precast components and subsequent concrete pouring. Compared with existing cast-in-place concrete floor slabs with post-tensioned prestressed structures, there is no need to wait for the post-tensioned prestressing construction to be completed and the grouting to reach strength before removing the support frame and formwork, reducing the turnover time of the support frame and formwork, further shortening the construction period and reducing construction costs.

[0066] Using lightweight material blocks can effectively reduce the structural self-weight, especially suitable for large-span, heavy-load floor slab scenarios. The lightweight material blocks are arranged in a regular horizontal and vertical pattern, with horizontal pipes placed between the lightweight material blocks perpendicular to the reinforcing ribs. The horizontal spacing is controlled within the range of 500~1000mm, which makes the reinforcement arrangement more concentrated. Combined with the use of post-tensioned prestressed steel bars, the performance of steel materials can be fully utilized, the number of steel bars can be reduced, the amount of steel used can be greatly saved, and the difficulty of on-site reinforcement threading can be reduced.

[0067] The floor slab is assembled from precast base plates and then poured with concrete to form a whole. The prestressing process after post-tensioning creates prestress between the precast components, which effectively improves the integrity and crack resistance of the floor slab. The bidirectional prestressing design makes the structural stiffness of the floor slab more consistent in both directions, and the bidirectional structural performance is similar. This can more effectively form a bidirectional force transmission floor slab, improving the overall load-bearing capacity and performance of the floor slab.

[0068] In this embodiment, the reinforcing rib (3) adopts two preferred structures, which are suitable for different engineering scenarios:

[0069] The first type of reinforcing rib (3) is a concrete rib. The concrete rib and the precast concrete base plate (2) are cast together in one piece. The cross section of the concrete rib is rectangular (or T-shaped according to design requirements). Stirrups (7) are arranged inside the concrete rib. The specifications of the stirrups (7) are Φ8@200, which can effectively increase the shear resistance between the concrete rib and the precast concrete base plate (2), improve the shear resistance between the cast-in-place concrete and the precast components, and thus enhance the overall shear bearing capacity of the composite components. This type of structure has good stiffness and low cost, and is suitable for engineering scenarios with strict cost control and moderate load.

[0070] The second type of reinforcing rib (3) is a steel pipe truss. The steel pipe truss uses a Φ89×3.5 round pipe as the upper chord and a continuously bent Φ12 steel bar as the web members. The web members are spaced 300mm apart. This structure can further improve the stiffness and bending strength of the precast concrete base plate (2). The finished steel rib does not need to be poured twice, which is conducive to the batch production of the precast base plate. At the same time, it can make the precast base plate thinner and reduce its self-weight, which is convenient for transportation and hoisting. It is suitable for engineering scenarios with large spans and heavy loads.

[0071] In addition, the reinforcing rib (3) can also be made of steel truss, steel pipe web truss, concrete truss rib, or corrugated steel plate and concrete composite rib (corrugated steel plate as web and concrete as upper flange) according to the engineering requirements. All of these can achieve the purpose of improving the stiffness and bending strength of the bottom plate and meet the stress requirements of each part of the component.

[0072] In this embodiment, the longitudinal prestressing tendon (4) is made of high-strength indented steel wire and is a pre-tensioned prestressed steel bar. By applying prestress through pre-tensioning, the crack resistance and bearing capacity of the precast concrete base plate (2) can be improved in advance, and the deformation of the component in the later stage can be reduced. The transverse distribution steel bar (5) is Φ6@200 and is arranged in the precast concrete base plate (2) and is arranged perpendicularly to the longitudinal prestressing tendon (4) to bear the transverse load and prevent the base plate from cracking.

[0073] In this embodiment, the transverse pipe (1) is a metal corrugated pipe with an inner diameter of 50mm. The metal corrugated pipe is easy to obtain and has an uneven surface, which can effectively increase the bonding force between the post-tensioned prestressed steel bars, the later grouting material and the concrete, and improve the overall working performance of the structure. The bottom surface of the transverse pipe (1) is lower than the upper surface of the precast concrete base plate (2) and is partially embedded in the precast concrete base plate (2). This setting can control the protective layer thickness of the post-tensioned prestressed steel bars to 25mm (less than 30mm), increase the lever arm of the post-tensioned prestressed steel bars, improve the load-bearing capacity of the component, reduce the amount of steel bars used, and at the same time keep consistent with the design model parameters, reducing the workload of design verification calculation.

[0074] In this embodiment, the transverse pipes (1) are arranged perpendicular to the longitudinal prestressed tendons (4) at intervals of 600mm (preferred value not less than 500mm). Appropriately increasing the spacing of the transverse pipes (1) is beneficial to component processing and reduces the number of reinforcing bars inserted. At the same time, after the spacing is increased, the material properties can be fully utilized by using post-inserted prestressed reinforcing bars to make up for the problem of increased steel bar calculation caused by the increased spacing. If the floor slab span is large, the spacing of the transverse pipes (1) can be adjusted to 500mm to further improve the floor slab bearing capacity.

[0075] In this embodiment, the lightweight material block (6) (weight reduction block) is a steel mesh box with dimensions of 600×600×120mm. The use of hollow material to replace concrete in areas with lower stress can effectively save concrete usage and reduce the self-weight of the structure. At the same time, the steel mesh box can be used as a lateral formwork for cast-in-place concrete ribs, forming a two-way concrete ribbed floor after pouring. If the project has high requirements for self-weight control, foam board can be used as the lightweight material block (6). The density of foam board is 12kg / m³, and the weight reduction effect is more significant. If the lightweight material block (6) is required to have a certain load-bearing capacity, a lightweight membrane shell can be used.

[0076] In this embodiment, the lightweight material block (6) and the precast concrete base plate (2) are cast together as one piece. The lightweight material block (6) and the precast concrete base plate (2) are precast in the factory, which can improve the efficiency of on-site installation and save the construction period. At the same time, it can effectively avoid the problem of the lightweight material block (6) floating when the cast-in-place concrete is poured, as well as the problem of the concrete directly below the lightweight material block (6) not being dense. If the on-site construction requires it, the lightweight material block (6) can also be placed on the precast concrete base plate (2) and fixed firmly to the precast concrete base plate (2) with expansion bolts, which can flexibly adapt to different construction scenarios.

[0077] In this embodiment, the lightweight material block (6) is set in the area enclosed by the reinforcing rib (3) and the transverse pipe (1). The reinforcing rib (3) and the transverse pipe (1) form a longitudinal and transverse orthogonal gap. The lightweight material block (6) is placed in this area. After pouring concrete, it can form concrete ribs and finally form a two-way dense rib floor slab, which improves the overall rigidity and load-bearing capacity of the floor slab.

[0078] In this embodiment, the method for manufacturing the prestressed composite slab includes the following steps:

[0079] Step 1: Clean the mold platform. Use a high-pressure water gun to wash the surface of the mold platform to remove surface debris and oil stains. After drying, use sandpaper to sand it flat to ensure that the flatness error of the mold platform surface does not exceed 2mm / m, so as to provide a good foundation for subsequent mold assembly and pouring.

[0080] Step 2: Assemble the mold according to the design drawings. Use steel formwork for mold assembly. Strictly control the mold size. The mold length error should not exceed 3mm and the width error should not exceed 2mm. After the mold is assembled, fix the mold with bolts and check the mold's firmness to prevent problems such as grout leakage and deformation during the pouring process.

[0081] Step 3: Apply release agent evenly to the inner wall of the mold using a brush. Use a water-based release agent and control the coating thickness to 0.1~0.2mm to ensure smooth demolding of subsequent components and avoid damaging the surface of the components.

[0082] Step 4: Arrange longitudinal prestressing tendons (4) and transverse distribution reinforcement (5) in the mold. Strictly control the position, spacing and protective layer thickness of the reinforcement according to the design requirements. The spacing of longitudinal prestressing tendons (4) is 200mm, the spacing of transverse distribution reinforcement (5) is 200mm, and the protective layer thickness is 15mm. Use spacers to fix the reinforcement to ensure that the reinforcement is arranged accurately.

[0083] Step 5: Tensioning operation is carried out on the longitudinal prestressed tendons (4) using a through-hole jack. The tensioning control value is 1395MPa. The tensioning sequence is from the middle to the sides, and the tensioning is done in stages. The tensioning value of each stage is 20% of the control value. After each stage of tensioning is completed, the load is held for 5 minutes to ensure that the prestress is applied evenly. After tensioning is completed, the anchor is used to anchor the tendons to prevent prestress loss.

[0084] Step 6: Fix the transverse distribution reinforcement (5), transverse pipe (1) and reinforcing rib (3). The transverse distribution reinforcement (5) and the longitudinal prestressing tendon (4) are connected by binding, with a binding point spacing of 300mm. The transverse pipe (1) is fixed to the transverse distribution reinforcement (5) by binding wire to ensure that the transverse pipe (1) is horizontal and accurately positioned, and crosses the reinforcing rib (3). The reinforcing rib (3) (concrete rib) is fixed by template. The template is firmly connected to the precast concrete base plate (2) mold to ensure that the reinforcing rib (3) is accurately positioned.

[0085] Step 7: Pour concrete. The concrete strength grade is C30. During the pouring process, use an immersion vibrator to vibrate the concrete at a frequency of 200Hz for 20-30 seconds per point to ensure that the concrete is dense and free from defects such as honeycomb or pitting. After pouring, use a screed to level the surface to ensure that the surface is flat and the flatness error does not exceed 3mm / m.

[0086] Step 8: Before the initial setting of the concrete (3-4 hours after pouring), place the lightweight material block (6) and insert the stirrups (7) on the concrete ribs to ensure that the lightweight material block (6) is accurately positioned and firmly fixed, and is tied to the transversely distributed steel bars (5).

[0087] Step 9: Curing of the poured components is carried out by covering them with geotextile and sprinkling water. The curing temperature is controlled at 20±5℃, the relative humidity is not less than 90%, and the curing time is 14 days. Water is sprinkled 3 to 4 times a day to ensure normal strength growth of the concrete.

[0088] Step 10: After the concrete strength reaches 75% of the design strength (C30 concrete strength reaches 22.5MPa), the longitudinal prestressed tendons (4) are released. The tendons are released slowly using jacks at a speed of 0.5MPa / min. The release process is uniform and slow to avoid impact stress on the components. After the release is completed, the tendons are removed from the plate and stored in categories. The storage site is flat and firm. The stacking height of the components does not exceed 3 layers. Each layer is separated by wooden blocks with a spacing of 1.5m. Protective measures are taken to prevent damage to the components.

[0089] In this embodiment, the method of using the prestressed composite slab includes the following steps:

[0090] Step 1: Transport the pre-fabricated prestressed composite slabs from the factory to the construction site using flatbed trailers. The components are separated by wooden blocks with a spacing of 1.5m. During transportation, take measures to secure and protect the components to prevent collisions and deformation. After arriving at the site, store the components according to their numbers. The storage area should be flat and firm to prevent the components from getting damp or damaged. The storage time should not exceed 3 months.

[0091] Step 2: According to the construction design requirements, temporary supports are laid in the construction area. The temporary supports adopt cup-lock scaffolding. The spacing between scaffolding uprights is 1.2m, the step distance of horizontal bars is 1.5m, and an adjustable top support is set on the top of the scaffolding. Timber is laid on the top support with a spacing of 300mm. The load-bearing capacity, spacing and stability of the temporary supports meet the design requirements to ensure that they can withstand the self-weight of the precast components and subsequent construction loads.

[0092] Step 3: According to the component number, use a tower crane to hoist the prestressed composite slab to the preset installation position. The hoisting adopts the four-point hoisting method. Soft protection is used between the hoisting wire rope and the component. The hoisting process is stable, slow and precise positioning. After the hoisting is completed, adjust the position of the component so that the horizontal pipes (1) of the adjacent prestressed composite slabs are aligned. The alignment error does not exceed 2mm to ensure smooth subsequent pipe connection.

[0093] Step 4: Use special plastic connectors to connect and fix the aligned horizontal pipes (1). Seal the connection with sealant to ensure no grout leakage. At the same time, set an air vent every 2m on the horizontal pipes (1). The air vents are made of Φ16 steel pipes and connected through special pipes. The upper part of the special pipes is 50mm higher than the design height of the subsequent concrete pouring to facilitate the discharge of air from the pipes during the pouring process and ensure that the grouting is dense.

[0094] Step 5: According to the design requirements, tie the slab surface reinforcement on the slab surface. The slab surface reinforcement uses Φ10@150. The specifications, spacing and anchorage length of the reinforcement meet the design specifications. After tying, use spacers to fix the reinforcement. The protective layer thickness is 20mm. Check the position and firmness of the reinforcement.

[0095] Step 6: Pass the transverse prestressing tendons through the transverse duct (1). The transverse prestressing tendons are made of Φs15.2 steel strands. The threading process is smooth to avoid bending or damage to the transverse prestressing tendons. After threading, adjust the position of the transverse prestressing tendons to ensure that they are centered and installed in place.

[0096] Step 7: Pour the concrete for the slab surface. During the pouring process, distribute the material evenly and use an immersion vibrator to compact it. Avoid touching the transverse pipe (1) and reinforcing bars during the vibration process to ensure that the concrete is tightly bonded to the precast components and free from quality defects such as honeycomb and pitting. After the pouring is completed, use a screed to level the surface and roughen it to facilitate subsequent surface construction.

[0097] Step 8: After the concrete strength of the slab reaches 75% of the design strength, tension the transverse prestressing tendons in Step 6. Use a through-hole jack for tensioning. The tensioning sequence is from the middle to the sides, and tensioning is done in stages. Each stage of tensioning is 20% of the control value. Hold the load for 5 minutes after each stage of tensioning. After tensioning, anchor the tendons with anchorages.

[0098] Step 9: According to the design requirements, grouting is carried out in the horizontal pipe (1). The grouting material is cement grout with a strength grade of M30. The grouting pressure is controlled at 0.5~0.8MPa. The grouting process is continuous and uniform to ensure that the grouting in the pipe is dense and without gaps. After the grouting is completed, the excess grouting material is cleaned up in time to ensure that the surface of the component is clean.

[0099] The order of steps 6 and 7 can be interchanged. If the on-site construction period is tight, the concrete slab can be poured first, and the transverse prestressing tendons can be installed after the concrete reaches a certain strength. The construction sequence can be flexibly adjusted to meet the construction period requirements.

[0100] Although embodiments of the 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 invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A prestressed composite slab, characterized by, The application relates to a prefabricated concrete bottom plate, which comprises transverse pipes (1), a prefabricated concrete bottom plate (2), reinforcing ribs (3), longitudinal prestressed tendons (4) and transverse distribution steel bars (5), wherein the transverse pipes (1) are arranged in a first direction and are partially embedded in the prefabricated concrete bottom plate (2), the transverse pipes (1) are parallel to a second direction, the length of the transverse pipes (1) is consistent with the width of the prefabricated concrete bottom plate (2), the longitudinal prestressed tendons (4) are arranged in the prefabricated concrete bottom plate (2) and are parallel to the first direction, the transverse distribution steel bars (5) are arranged in the prefabricated concrete bottom plate (2) and are parallel to the second direction, the reinforcing ribs (3) are arranged in the prefabricated concrete bottom plate (2) and are parallel to the first direction, the bottom of the reinforcing ribs (3) is fixedly connected with the prefabricated concrete bottom plate (2), the first direction is the length direction of the prefabricated concrete bottom plate (2), the second direction is the width direction of the prefabricated concrete bottom plate (2), the first direction and the second direction are perpendicular to each other, and the plane formed by the first direction and the second direction is parallel to the surface of the prefabricated concrete bottom plate (2).

2. The prestressed composite slab according to claim 1, characterized in that, The bottom of the transverse pipe (1) is higher than the top of the longitudinal prestressed tendon (4) and is lower than the upper surface of the prefabricated concrete bottom plate (2).

3. The prestressed composite slab as claimed in claim 1, wherein, The transverse pipe (1) is a metal bellows.

4. The prestressed composite slab as claimed in claim 1, wherein, The upper surface of the prefabricated concrete bottom plate (2) is fixedly provided with light material blocks (6).

5. The prestressed composite slab as claimed in claim 1, wherein, The reinforcing rib (3) is any one of the following structures: a concrete rib, which is integrally formed with the prefabricated concrete bottom plate (2), and the cross section of the concrete rib is rectangular or T-shaped; a steel pipe truss, which is formed by a round pipe or a flat pipe as a top chord and continuous bent steel bars as web members; a concrete truss combined rib, which is formed by concrete or reinforced concrete as a top chord and bent steel bars or steel pipes as web members; a prestressed concrete truss combined rib, which is formed by an outer steel skin structure as a top chord, prestressed steel bars arranged in the inner part and concrete poured, and bent steel bars, steel pipes or bent corrugated steel plates as web members.

6. A prestressed composite slab as claimed in claim 5, wherein, When the reinforcing rib (3) is a concrete rib, the concrete rib is arranged with stirrups (7) or continuous bent wave bars (8).

7. The prestressed composite slab as claimed in claim 4, wherein, The light material block (6) is a steel mesh box, a light membrane shell or a foam plate.

8. The prestressed composite slab as claimed in claim 4, wherein, The light material block (6) is integrally poured with the prefabricated concrete bottom plate (2).

9. The prestressed composite slab as claimed in claim 4, wherein, The light material block (6) is placed on the prefabricated concrete bottom plate (2) and is fixedly connected with the prefabricated concrete bottom plate (2).

10. The prestressed composite slab as claimed in claim 4, wherein, The light material block (6) is arranged in the area surrounded by the reinforcing rib (3) and the transverse pipe (1).

11. A method of manufacturing the prestressed composite slab according to any one of claims 1 to 10, characterized by, The application further relates to a prefabricated concrete bottom plate manufacturing method, which comprises the following steps: Step 1: cleaning a mold table to ensure that the surface of the mold table is flat and free of sundries; Step 2: assembling a mold according to design drawings to ensure that the size of the mold meets the design specification; Step 3: uniformly brushing a release agent on the inner wall of the mold; Step 4: arranging longitudinal prestressed tendons (4) and transverse distribution steel bars (5) in the mold to ensure that the positions and intervals of the steel bars meet the design requirements; Step 5: performing tensioning operation on the longitudinal prestressed tendons (4) to ensure that the tensioning control value meets the design standard. Step 6: Fix the transverse pipe (1) and the reinforcing rib (3) in the preset position to ensure firm installation and accurate position; Step 7: Pour the concrete and perform the vibrating operation during the pouring process to ensure the compactness of the concrete, and perform the leveling treatment on the slab surface after the pouring is completed; Step 8: Place the lightweight material block (6) before the initial setting of the concrete, and insert the stirrup (7) on the concrete rib when the reinforcing rib (3) is the concrete rib; Step 9: Perform the curing operation on the poured component, and the curing condition meets the concrete curing specification; Step 10: After the strength of the concrete reaches the design requirement, perform the tensioning treatment on the longitudinal prestressed tendon (4), and then lift the slab for storage.

12. A method of using the prestressed composite slab as claimed in any one of claims 1-10, characterized in that, The method comprises the following steps: Step 1: Transport the factory-prepared prestressed composite slab bottom plate to the construction site and store it in a classified manner; Step 2: According to the construction design requirement, lay the temporary support in the construction area to ensure that the bearing capacity of the temporary support meets the requirement; Step 3: According to the component number, hoist the prestressed composite slab to the preset installation position, and align the transverse pipe (1) of the adjacent prestressed composite slab; Step 4: Connect and fix the aligned transverse pipe (1) by using the connecting piece to ensure that the connecting part is not leaked; meanwhile, a plurality of air leakage holes are arranged on the transverse pipe (1), the air leakage holes are connected through a special pipe, and the upper part of the special pipe is higher than the design height of the subsequent poured concrete; Step 5: According to the design requirement, bind the slab steel bars on the slab surface of the prestressed composite slab; Step 6: Pass the transverse prestressed tendon (9) through the transverse pipe (1), and ensure that the transverse prestressed tendon (9) is installed in place; Step 7: Pour the slab surface concrete to ensure the compactness of the concrete pouring; Step 8: After the strength of the slab surface concrete reaches the design requirement, perform the tensioning operation on the transverse prestressed tendon in step 6; Step 9: According to the design requirement, perform the grouting operation in the transverse pipe (1), and the grouting quality meets the relevant specification; The operation sequence of step 6 and step 7 can be exchanged.

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