Supporting-free and mold-free prestressed dense rib hollow laminated floor system and construction method thereof

Abstract

The invention provides a support-free and mold-free prestressed dense rib hollow laminated floor system and a construction method thereof. The problems that in the prior art, mold erecting is complex, joints are single, the joint adaptability is poor, and durability is insufficient are solved. The floor system comprises a prefabricated dense rib hollow module, prestressed tendons, a cast-in-place laminated layer, double-type beam column joints and five kinds of midspan joint structures, supporting and mold-free are achieved through a reinforcing mold box and a supporting pad, and a drainage structure is arranged to optimize durability. The construction method is implemented according to the processes of prefabricating, splicing, joint / node processing, tensioning and laminated layer pouring. The scheme adapts to multiple scenes, shortens the construction period, reduces the self weight, improves the structural integrity and the industrial construction efficiency, and gives consideration to both the bearing capacity and the space utilization rate.

Description

Technical Field

[0001] This invention belongs to the field of building engineering technology, specifically relating to a prestressed dense rib hollow composite floor slab that requires no support or formwork and its construction method. Background Technology

[0002] With the rapid development of industrialized construction, precast assembled floor slabs have become an industry trend due to their advantages such as high construction efficiency and environmental friendliness. Ribbed floor slabs, prestressed floor slabs, and hollow composite floor slabs are currently the mainstream forms of large-span floor slabs, but existing technologies have many shortcomings: Traditional cast-in-place / precast ribbed floor slabs: require the erection of full-span scaffolding and a large number of wooden / steel formworks. The formwork erection and dismantling process is complicated, with a large amount of wet work, long construction period, high labor and material costs, and poor overall integrity of ribbed module splicing, with the mid-span joints prone to cracking. Prestressed ribbed floor slabs: Although they can achieve large spans of 8 to 24 meters, most require the construction of a support system, making it impossible to achieve support-free construction. The prestressed tensioning ends are prone to water accumulation and corrosion, resulting in poor durability. Furthermore, beam-column joints often adopt traditional column cap designs, which occupy the building's net height and have low space utilization. Hollow composite floor slabs: They are relatively lightweight, but the mid-span joint connection is limited to a single form, which can only be adapted to conventional construction scenarios and cannot meet the differentiated needs of precision, cost and efficiency. The beam-column joints have not formed an adaptation system of "with column cap / without column cap". Under heavy load scenarios, the column top is prone to punching shear failure, while under conventional scenarios, the column cap causes space waste. Existing technologies have not formed a systematic solution: they have not organically combined "support-free and formwork-free, prestressed close-ribbed, hollow composite, differentiated joints, adaptable beam-column joints, and durable structure", and cannot simultaneously meet the comprehensive needs of large span, industrialized construction, high load-bearing capacity, high durability, and space optimization.

[0003] Therefore, developing a prestressed ribbed hollow composite floor system that truly achieves support-free and formwork-free operation, adapts to multiple scenarios, has a large span, and is highly durable has become an urgent technical problem to be solved in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a prestressed ribbed hollow composite floor slab without support or formwork and its construction method. The aim is to achieve a completely support-free and formwork-free construction process for the floor slab, eliminating the need for full-scale scaffolding and traditional formwork, significantly improving construction efficiency and reducing costs. It offers five differentiated mid-span joint structures to adapt to different construction precision, cost, and efficiency requirements, improving the integrity and crack resistance of the joints. It designs beam-column nodes with and without column caps, balancing the load-bearing capacity of heavy-load scenarios with the space utilization of conventional scenarios. It optimizes the prestressing tensioning end structure and adds a drainage system to improve the durability of the prestressed system. Combining prestressing technology with a hollow ribbed structure, it achieves large spans of 8-24m while reducing the floor slab's self-weight and vertical structural load.

[0005] In a first aspect, this invention proposes a prestressed ribbed hollow composite floor slab that requires no support or formwork, comprising precast ribbed hollow modules, prestressing tendons, cast-in-place composite layers, beam-column joints, and mid-span joint structures. The precast ribbed hollow modules are provided with reinforcing molds, which replace traditional formwork to form the casting cavity. The bottom of the precast ribbed hollow modules is temporarily supported by supports, which replace full-span scaffolding to achieve support-free construction. The prestressing tendons pass through reserved channels in the precast ribbed hollow modules. The cast-in-place composite layer is cast above the precast ribbed hollow modules and forms an integral load-bearing structure with the modules. The beam-column joints are available in two structural forms: with and without column caps. The mid-span joint structure is used for splicing adjacent precast ribbed hollow modules.

[0006] This system achieves a fully formwork-free floor slab construction process, eliminating the need for full-span scaffolding and traditional formwork, significantly reducing labor and material costs. Dual types of beam-column joints and mid-span seams adapt to various scenarios, while prestressed and composite structures ensure load-bearing capacity for large spans, improving structural integrity and construction efficiency.

[0007] Preferably, the mid-span joint structure is any one of the following: cast-in-place micro-expansion concrete tightening joint, bolt and nut tightening joint, wedge-shaped cement block tightening joint, or welded steel plate rigid joint. These four types of mid-span joints can be adapted to different precision, cost, and load scenarios, flexibly meeting project requirements. They balance construction efficiency and structural performance, avoiding the limitations of single joints and broadening the application range of floor slab systems.

[0008] Preferably, the bolt and nut tightening joint is either a bolt unscrew tightening joint or a bolt tightening tightening joint. These two bolt tightening methods adapt to different precision requirements, require no maintenance waiting time, and shorten the construction cycle. Balancing flexibility and stability, it facilitates rapid industrial construction while ensuring reliable force transmission at the mid-span joint.

[0009] Preferably, the column-cap-less node includes a steel corbel, a precast composite beam, and a cast-in-place node area. The steel corbel is embedded in the side of the frame column, the precast composite beam is erected on the steel corbel, and the cast-in-place node area is cast at the junction of the precast composite beam and the frame column to form a rigid connection. The combination of the steel corbel support and the cast-in-place node eliminates the need for a column cap, optimizes the headroom, and forms a rigid connection to ensure load-bearing capacity. This design is suitable for scenarios such as shopping malls and office buildings where headroom is paramount, while also considering seismic performance, aligning with the logic of efficient industrialized construction.

[0010] Preferably, the column-capped node includes a column cap, a solid support plate, and multiple reinforcements. The column cap is positioned at the top of the frame column, and the solid support plate is laid around the precast ribbed hollow module area surrounding the column cap. The multiple reinforcements include column cap tie bars, horizontal circumferential bars, and slab surface reinforcements. The column cap and solid support plate enhance punching shear resistance, while the multiple reinforcements improve node stiffness, making it suitable for heavy-load scenarios. This avoids punching shear failure at the column top, achieves uniform load transfer, ensures coordinated stress distribution between the floor slab and the column, and improves structural safety.

[0011] Preferably, the reinforcing formwork is equipped with a drainage structure, which includes a drainage slope and drainage holes in the bottom plate. The drainage holes in the bottom plate penetrate the bottom plate of the precast ribbed hollow module. The addition of a drainage structure to the reinforcing formwork, penetrating the bottom plate of the module, allows for the drainage of accumulated water, preventing water accumulation in the pouring cavity from affecting the quality of concrete pouring, and also preventing corrosion of the module's bottom plate. This adapts to damp construction scenarios and further improves the durability and construction reliability of the floor system.

[0012] Preferably, the prefabricated ribbed hollow modules adopt a standardized 1290mm modular layout, with a 10mm-20mm splicing gap reserved at the edges of the modules. This modular layout and reserved gaps facilitate standardized production and on-site fine-tuning, reducing waste and improving assembly efficiency. It ensures a neat floor slab layout, meets the needs of industrialized construction, and helps achieve rapid construction and cost control.

[0013] Secondly, embodiments of the present invention provide a construction method for a prestressed ribbed hollow composite floor slab that requires no support or formwork, for fabricating the aforementioned prestressed ribbed hollow composite floor slab, comprising the following steps: S1. Factory-prefabricated dense rib hollow modules, with prestressed tendon channels and splicing structures reserved inside the modules; S2. The prefabricated ribbed hollow modules are hoisted on site, and temporary support is provided for the modules using supports. Reinforcing molds are installed on the outside of the modules to form a casting cavity. S3. The mid-span joint structure is used to complete the splicing of adjacent prefabricated ribbed hollow modules, and at the same time, the reinforcement binding and closure of the beam-column joint are completed. S4. Pour the cast-in-place concrete in the beam-column joint area and mid-span joint. After the concrete strength reaches the design requirements, tension the prestressed tendons and complete the anchorage. S5. Pour the upper cast-in-place composite layer, seal and protect the joints and seams, and complete the floor slab construction.

[0014] The streamlined process enables industrialized construction without supports or formwork, reducing wet work and the use of reusable materials. Standardized joint and node construction and prestressing tensioning sequence ensure the integrity and load-bearing performance of the floor slab, significantly shortening the construction period and reducing costs.

[0015] Preferably, in step S3, when the beam-column joint is a joint without a column cap, a steel structure corbel needs to be pre-embedded on the side of the frame column first, and then the precast composite beam is erected on the steel structure corbel and the steel reinforcement is anchored. In step S3, if the beam-column joint uses a column cap joint, the column cap should be tied with multiple reinforcements first, a solid area support plate should be laid, and then the splicing of the precast ribbed hollow modules should be completed.

[0016] The steel bracket pre-embedding and precast beam erection process is adapted to construction without column caps, simplifying the support procedures. Precise control of node positioning ensures reliable rebar anchorage, achieving a balance between optimized clearance and efficient construction. Column cap reinforcement and solid zone installation are completed first to strengthen the node's load-bearing capacity before module assembly. Adaptable to heavy-load scenarios, it ensures node stress meets standards, avoids structural hazards caused by improper construction sequence, and guarantees construction quality.

[0017] Preferably, in step S4, after the prestressing tendons are tensioned, the tensioning ends of the prestressing tendons are grouted and sealed, and drainage is completed at the tensioning ends through the drainage holes in the bottom slab. The combination of grouting and sealing at the tensioning ends and drainage treatment both fixes the prestressing tendons and prevents water accumulation and corrosion. This improves the durability of the prestressing system, ensures long-term stable operation of the tendons, and extends the service life of the floor slab.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Construction efficiency and cost optimization: Reinforced formwork is used to replace traditional formwork and supports are used to replace full-span scaffolding, achieving full-process support and formwork-free construction, reducing the amount of turnover materials, reducing labor costs, and shortening the construction period; 1290mm modular prefabricated modules can be quickly assembled on site and are suitable for industrialized construction.

[0019] (2) Comprehensive improvement of structural performance: Prestressed technology enables large spans of 8~24m, with small floor deflection and excellent crack resistance; hollow ribbed structure reduces the self-weight of the floor by 30%~40%, reducing the vertical structural load; five different joints and double-fit nodes ensure the integrity of the floor, and the punching shear resistance of column cap nodes is improved by more than 60% under heavy load scenarios.

[0020] (3) Space and durability optimization: The no-column-cap node increases the building height by 15%~20%, while the column-cap node is adapted to heavy load requirements, taking into account both space utilization and load-bearing capacity; the prestressed tension end drainage slope + bottom plate drainage hole completely solves the problem of water accumulation and corrosion, and improves structural durability.

[0021] (4) Green and environmentally friendly: Prefabricated components are produced in factories, reducing the amount of wet work on site, and significantly reducing construction waste, dust and noise, which is in line with green building and dual carbon goals. Attached Figure Description

[0022] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0023] Figure 1 This is a three-dimensional axonometric drawing of the entire floor slab without column caps according to an embodiment of the present invention; Figure 2 This is a 3D axonometric drawing of a floor slab module without column caps according to an embodiment of the present invention. Figure 3 This is a three-dimensional axonometric drawing of the mid-span joint structure of a floor slab without column caps, according to an embodiment of the present invention. Figure 4 This is a plan view of a prestressed ribbed hollow composite floor slab without column caps, according to an embodiment of the present invention. Figure 5 , Figure 6 and Figure 7 This is a schematic diagram of the beam-column connection node construction according to an embodiment of the present invention; Figure 8 This is a support connection diagram of the precast base plate and frame beam connection structure according to an embodiment of the present invention; Figure 9 and Figure 10 This is a schematic diagram of a cross-span joint construction method according to an embodiment of the present invention; Figure 11 , Figure 12 and Figure 13 This is a schematic diagram of a second method for a mid-span joint according to an embodiment of the present invention; Figure 14 and Figure 15 This is a schematic diagram of method three for the mid-span joint according to an embodiment of the present invention; Figure 16 , Figure 17 and Figure 18 This is a schematic diagram of the fourth method of the mid-span joint according to an embodiment of the present invention; Figure 19 , Figure 20 and Figure 21 This is a schematic diagram of the fifth method of the mid-span joint according to an embodiment of the present invention; Figure 22 , Figure 23 and Figure 24 A detailed view of the prestressed tensioning end structure according to an embodiment of the present invention; Figure 25 , Figure 26 and Figure 27This is a detailed diagram of the anchorage between the transverse secondary beam and the frame beam in an embodiment of the present invention; Figure 28 This is a three-dimensional axonometric view of the column-capped floor slab according to an embodiment of the present invention; Figure 29 This is a 3D axonometric view of the assembled column-capped floor slab module according to an embodiment of the present invention; Figure 30 This is a three-dimensional axonometric view of the mid-span joint structure of a floor slab with column caps according to an embodiment of the present invention. Figure 31 This is a plan view of a prestressed ribbed hollow composite floor slab with column caps, according to an embodiment of the present invention. Figure 32 , Figure 33 and Figure 34 Detailed diagram of the cap connection method according to an embodiment of the present invention; Figure 35 This is a reinforcement diagram of the cast-in-place column and column cap according to an embodiment of the present invention; Figure 36 This is a schematic flowchart illustrating the construction method of the prestressed ribbed hollow composite floor slab without support or formwork, according to an embodiment of the present invention.

[0024] Reference numerals: 1. Precast ribbed hollow module; 2. Prestressed tendon; 3. Cast-in-place composite layer; 4. Beam-column joint; 5. Mid-span joint construction; 6. Reinforcing formwork; 7. Support; 8. Steel structure corbel; 9. Precast composite beam; 10. Solid area support plate; 11. Column cap tie bar; 12. Horizontal circumferential reinforcement; 13. Slab surface reinforcement; 14. Drainage structure; 15. Tightening groove; 16. Cast-in-place micro-expansion concrete layer; 17. Embedded nut; 18. Fastening bolt; 19. Wedge-shaped cement block; 20. Splicing cavity; 21. Welded connecting steel plate; 22. T-shaped connector; 23. Prestressed steel strand. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] In a first aspect, embodiments of the present invention disclose a prestressed, densely ribbed, hollow composite floor slab that requires no support or formwork, such as... Figures 1-7As shown, the structure includes a precast ribbed hollow module 1, prestressed tendons 2, a cast-in-place composite layer 3, beam-column joints 4, and a mid-span joint structure 5. A reinforcing mold 6 is installed on the precast ribbed hollow module 1, which replaces traditional formwork to form the casting cavity. The bottom of the precast ribbed hollow module 1 is temporarily supported by supports 7, which replace full-span scaffolding for support-free construction. The prestressed tendons 2 pass through the reserved channels of the precast ribbed hollow module 1. The cast-in-place composite layer 3 is poured above the precast ribbed hollow module 1 and forms an integral load-bearing structure with the module. The beam-column joint 4 has two structural forms: with and without column caps. The mid-span joint structure 5 is used for splicing and connecting adjacent precast ribbed hollow modules 1.

[0028] Specifically, this embodiment is a prestressed ribbed hollow composite floor slab without column capitals, and its overall structure is as follows: Figures 1-3 3D diagram and Figure 4 The plan layout without column caps is shown below: The total dimensions of the floor slab are 23400mm×8100mm, and the column grid is arranged at 7800mm×8100mm. The frame columns are located at the four corners and the middle, forming a two-way load-bearing system.

[0029] The core components include: 1. Precast ribbed hollow modules, 6. Reinforcing molds, 7. Supports, 2. Prestressed tendons, 3. Cast-in-place composite layer, 4. Beam-column joints without column caps, and 5. Five types of mid-span joint structures.

[0030] The prefabricated ribbed hollow modules 1 are arranged in two directions according to the 1290mm standardized module to form a regular ribbed grid. A splicing gap of 10mm-20mm is reserved at the edge of the module. The frame beams (inverted T-shaped frame composite beams, combined frame composite beams, etc.) are arranged through the column grid and are seamlessly connected with the modules to jointly bear the floor load.

[0031] The module is equipped with a reinforcing mold box 6, which has a drainage structure 14. The drainage structure 14 includes a 2% drainage slope and drainage holes in the bottom plate. The drainage holes in the bottom plate penetrate the bottom plate of the precast ribbed hollow module 1. The bottom of the module is supported by a support pad 7, which completely eliminates the need for full-span scaffolding and traditional formwork, and realizes construction without support or formwork. The prestressed tendons 2 are arranged in both directions along the reserved channels (corrugated metal pipes) of the beam and the module, which can meet the needs of large spans of 8~24m.

[0032] Construction of beam-column joint without column cap: Figure 5 , Figure 6 and Figure 7 This is a schematic diagram of the beam-column connection method. In this embodiment, the node without column cap includes a steel structure corbel 8, a precast composite beam 9, and a cast-in-place node area. The steel structure corbel 8 is embedded in the side of the frame column, the precast composite beam 9 is erected on the steel structure corbel 8, and the cast-in-place node area is cast at the junction of the precast composite beam 9 and the frame column to form a rigid connection.

[0033] Column-cap-less joints are suitable for common scenarios with high building clearance requirements, such as shopping malls and office buildings, and are constructed as follows: Support system: Holes are pre-drilled during the construction of the frame columns, and steel structure brackets 8 are installed later as temporary supports and force transmission components for the precast composite beams 9, eliminating the need for a full-span scaffold.

[0034] Beam connection: The inverted T-shaped frame composite beam and the combined frame composite beam are precisely hoisted and erected on the steel structure bracket 8. The longitudinal reinforcement of the beam extends into the frame column and is anchored according to the design length to ensure continuous force transmission of the reinforcement. The longitudinal reinforcement of the frame column is concentrated at the corner to optimize the stress performance of the column section, while reserving space for the anchorage of the beam reinforcement.

[0035] Cast-in-place joints: The beam-column junction is sealed with a reinforcing mold 6 to form a casting cavity for the cast-in-place joint area; after the concrete is poured, the precast beam and the cast-in-place joint area form a rigid connection, ensuring the integrity and seismic performance of the structure.

[0036] Floor slab layers: total thickness 400mm, upper 100mm cast-in-place layer (with slab reinforcement), lower 300mm precast beam / slab layer, beam bottom supported by support pad 7, reinforcement formwork 6 set on the outside of the splice, forming a formwork-free casting cavity.

[0037] Support connection diagram as shown Figure 8 As shown. Connection structure between the precast base slab and the frame beam: Structural composition: The total thickness of the floor slab is 400mm, including a 100mm cast-in-place layer (with slab reinforcement), a 230mm precast layer (hollow ribbed precast base slab + precast main beam), and a 70mm base slab layer; the bottom of the precast base slab is supported on the top of the precast main beam by support pads 7, replacing full-span scaffolding; reinforcement molds 6 are set on the outside of the splice to form a closed casting cavity; prestressed steel bars, ordinary steel bars and distribution steel bars are configured in the precast base slab, and bottom steel bars (prestressed or ordinary steel bars) are configured in the precast main beam; the splice gap (20mm) is filled with grout and sealed with mortar or PE rods on the outside to ensure airtightness.

[0038] The process involves: hoisting the precast main beam to the top of the frame column; hoisting the hollow ribbed precast base slab and supporting it on top of the precast main beam using support pads 7; adjusting the splicing gap to 20mm; installing reinforcing molds 6 to seal the splice joints; injecting grout, and sealing the outside with mortar / PE rods after hardening; tying the reinforcing bars of the cast-in-place slab and pouring a 100mm thick cast-in-place layer to form an integral whole with the precast components. The combination of support pads 7 and reinforcing molds 6 eliminates the need for traditional supports and formwork, improving construction efficiency; the joint treatment of the grout and pointing ensures density and impermeability, preventing later cracking and leakage.

[0039] Methods for connecting mid-span joints, as shown in steps one through five. Figure 9-21 As shown. The five types of mid-span joint constructions are as follows: This invention provides five differentiated mid-span joint structures 5, which can be any one of the following: cast-in-place micro-expansion concrete tightening joint, bolt and nut tightening joint, wedge-shaped cement block tightening joint, and welded steel plate rigid joint. Among them, the bolt and nut tightening joint can be any one of bolt unscrew tightening joint or bolt tightening tightening joint, and can be flexibly selected according to the requirements of construction accuracy, cost, and efficiency. (1) Cast-in-place micro-expansion concrete top-tight joint ( Figure 9 , Figure 10 Method 1 for cross-section joint Structural composition: A pre-reserved tightening groove 15 (20mm wide and 100mm deep) is reserved at the splicing end of adjacent precast ribbed hollow modules 1, and a cast-in-place micro-expansion concrete layer 16 is poured in the groove; a reinforcing mold box 6 is set on the outside of the splice to form a closed cavity; prestressed tendons 2 are inserted into the metal corrugated pipe; shear keys are set at the beam end to enhance the shear resistance of the joint; the splice gap is filled with grout and sealed with mortar / PE rod on the outside.

[0040] Prefabrication in the factory involves pre-reserving a top-tightening groove 15; on-site hoisting of the module, aligning it with the top-tightening groove 15, and installing the reinforcing mold 6; pouring micro-expansion concrete, vibrating to compact it, and curing; after the concrete strength reaches 70% of the design strength, tensioning the prestressing tendons 2 and grouting to seal the corrugated pipes; binding the cast-in-place reinforcement and pouring a 100mm thick cast-in-place layer. By utilizing micro-expansion concrete to compensate for shrinkage, it ensures a tight and compact joint, exhibiting excellent crack resistance and sealing properties, making it suitable for industrial plants, underground garages, and other scenarios with extremely high requirements for joint compaction.

[0041] (2) Unscrew the bolts and tighten the joint. Figures 11-13 Method 2 for mid-span joint Structural composition: The splicing end of the prefabricated ribbed hollow module 1 is pre-embedded with a pre-embedded nut 17. After the adjacent modules are hoisted, the fastening bolts 18 cooperate with the pre-embedded nuts 17 to achieve unscrewing and tightening. A reinforcing mold box 6 is set on the outside of the splice, and the prestressed tendons 2 are inserted into the metal corrugated pipe. Shear keys are set at the beam end, the splice gap is filled with grout, and the outside is sealed with mortar / PE rod.

[0042] Construction steps: Nuts 17 are pre-embedded during factory prefabrication → Modules are hoisted on site and tightened by unscrewing bolts 18 to ensure a tight fit → Reinforcing mold 6 is installed, grout is poured and the outer side is sealed → Prestressed tendons 2 are tensioned and corrugated pipes are grouted and sealed → Cast-in-place reinforcement is tied, and a 100mm thick cast-in-place layer is poured. No need to wait for concrete curing, the construction cycle is shortened by more than 30%, suitable for commercial projects and office buildings with tight schedules, while ensuring splicing accuracy and shear resistance.

[0043] (3) Tighten bolts to secure the joint ( Figure 14 , Figure 15 Method 3 for cross-section joint Structural composition: Precast ribbed hollow modules 1 have pre-embedded nuts 17 at the splicing ends. After adjacent modules are hoisted, they are tightened by fastening bolts 18 in conjunction with the pre-embedded nuts 17. A reinforcing mold box 6 is set on the outside of the splice, and the prestressed tendons 2 are inserted into the metal corrugated pipe. Shear keys are set at the beam ends, and the splice gaps are filled with grout and sealed with mortar / PE rods on the outside.

[0044] Construction steps: Nuts 17 are pre-embedded during factory prefabrication → Modules are hoisted on site and tightened using bolts 18 to ensure splicing accuracy → Reinforcing mold 6 is installed, grout is poured and the outer side is sealed → Prestressed tendons 2 are tensioned and corrugated pipes are grouted and sealed → Cast-in-place reinforcement is tied, and a 100mm thick cast-in-place layer is poured. This design offers higher splicing stability and is suitable for large-span floor slabs with strict precision requirements; the post-tightening design facilitates on-site fine-tuning, improves construction tolerance, and ensures joint integrity and crack resistance.

[0045] (4) The wedge-shaped cement block is tightly pressed against the joint. Figures 16-18 Method 4 for cross-section joint Structural composition: The splicing ends of adjacent precast ribbed hollow modules 1 are reserved with a top-tightening groove 15 (20mm wide and 100mm deep). A wedge-shaped cement block 19 is placed in the top-tightening groove 15 to achieve top-tight splicing by utilizing its self-locking property. The splicing cavity 20 is sealed by cast-in-place concrete. A reinforcing mold box 6 is set on the outside of the splicing point to form a closed casting cavity. The cast-in-place composite layer 3 concrete is poured inside. The splicing gap (10mm) is filled with grout to make it dense, and the outside is sealed with mortar. The total thickness of the floor slab is 400mm, with a 100mm cast-in-place layer at the top (with slab reinforcement), a 230mm precast / cast-in-place bonding layer in the middle, and a 70mm hollow ribbed precast bottom slab at the bottom (with ordinary / prestressed steel bars and distribution bars). Prestressed steel strands 23 are arranged at the bottom of the beam.

[0046] Construction steps: Pre-determine placement positions for wedge-shaped cement blocks 19 during factory prefabrication → Hoist the modules on site, placing the wedge-shaped cement blocks 19 between the splicing ends to achieve tight clamping → Install reinforcing mold boxes 6 to seal the splicing joints, forming the casting cavity → Inject grout, and after hardening, seal the outer side with mortar grouting → Tie the reinforcing bars of the cast-in-place slab, and pour a 100mm thick cast-in-place layer to form an integral whole with the prefabricated components. Wedge-shaped cement blocks 19 are low-cost, easy to install, require no concrete curing, significantly reduce on-site wet work, lower construction costs, and are suitable for projects with conventional precision requirements.

[0047] (5) Rigid joints of welded steel plates Figures 19-21 Method 5 for cross-section joint Structural composition: The bottom steel bars of the beams at the ends of the precast ribbed hollow module 1 are welded to the welded connecting steel plates 21 on both sides to form a rigid connection; T-shaped butt welded T-shaped overjoints 22 are set at the splice to further enhance the force transmission performance of the joint; the splice gap (20mm) is filled with grout and sealed with mortar on the outside; the total thickness of the floor slab is 400mm, with a 100mm cast-in-place layer at the top (with slab reinforcement), a 230mm precast / cast-in-place bonding layer in the middle, and a 70mm hollow ribbed precast bottom slab at the bottom (with ordinary / prestressed steel bars and distribution bars), and prestressed steel strands 23 are arranged at the bottom of the beams.

[0048] Construction steps: During factory prefabrication, bottom reinforcing bars are pre-reserved at the ends of the modules for welding to the welded connection steel plate 21. The modules are then hoisted on-site, and the bottom reinforcing bars are welded to the welded connection steel plate 21 on both sides. T-shaped connectors 22 are installed. Reinforcing mold boxes 6 are installed to seal the joints, forming a casting cavity. Grouting material is poured, and after hardening, the outer side is sealed with mortar. The surface reinforcing bars of the cast-in-place slab are tied, and a 100mm thick cast-in-place layer is poured, forming an integral whole with the prefabricated components. The double-sided welding of the welded steel plate and reinforcing bars forms a rigid connection. The T-shaped connectors 22 enhance force transmission, significantly improving the tensile and torsional resistance of the joints and completely solving the problem of dispersion in prefabricated joints. This method is suitable for heavy-load, large-span critical parts.

[0049] Detailed diagram of tensioning end as follows Figures 22-24 As shown. Prestressed tensioning end structure: Structural Composition: A 2% drainage slope is provided at the tensioning end, and drainage holes are configured in the bottom plate, which work in conjunction with the drainage structure 14 of the reinforcing formwork 6 to form an all-round drainage system; the prestressing tendons 2 are inserted into the metal corrugated pipes, and are grouted and sealed after tensioning to form a prestressed system; the total thickness of the floor slab is 400mm, with a 100mm cast-in-place layer at the top (with slab reinforcement), a 230mm precast / cast-in-place bonding layer in the middle, and a 70mm hollow ribbed precast bottom slab at the bottom (with ordinary / prestressed reinforcement and distribution reinforcement), and prestressed steel strands 23 are configured at the bottom of the beams; the reinforcing formwork 6 is set at the tensioning end to form a closed casting cavity, with the cast-in-place part inside and the precast part below.

[0050] During factory prefabrication, a corrugated metal pipe channel and a drainage hole in the bottom slab are reserved at the tensioning end. → Reinforcing mold 6 is installed on site to form a casting cavity with a 2% drainage slope. → Prestressed steel strands 23 are threaded through the concrete. After the strength of the cast-in-place concrete reaches the standard, prestressing is performed. → After tensioning, the corrugated metal pipe is grouted and sealed, and the accumulated water is drained through the drainage hole in the bottom slab. → The reinforcing steel bars of the cast-in-place slab are tied, and a 100mm thick cast-in-place layer is poured to complete the construction of the tensioning end.

[0051] Anchorage details of the transverse secondary beam and frame beam are as follows: Figures 25-27 As shown. Anchorage structure between the transverse secondary beam and the frame beam: Structural composition: The reinforcing bars of the transverse secondary beams extend into the frame beams and are anchored according to the design length to form a reliable force transmission node; a reinforcing formwork 6 is set in the anchorage area to form a closed casting cavity, with the inside being the cast-in-place part and the bottom being the precast part; the total thickness of the floor slab is 400mm, with a 100mm cast-in-place layer at the top (with slab reinforcement), a 230mm precast / cast-in-place bonding layer in the middle, and a 70mm hollow ribbed precast bottom slab at the bottom (with ordinary / prestressed steel bars and distribution bars), and prestressed steel strands 23 are set at the bottom of the beams; a 2% drainage slope and drainage holes are set in the anchorage area, which work in conjunction with the drainage structure 14 at the tensioning end to avoid water accumulation and corrosion.

[0052] During factory prefabrication, anchoring steel bars are reserved at the ends of the transverse secondary beams. → The transverse secondary beams are hoisted on site, and the anchoring steel bars are extended into the frame beams to complete the anchoring according to the design length. → The reinforcement mold box 6 is installed to close the anchoring area and form the casting cavity. → The cast-in-place slab surface steel bars are tied, and a 100mm thick cast-in-place layer is poured to form an integral whole with the prefabricated components. → The accumulated water is drained through the drainage holes of the bottom slab to complete the anchoring construction.

[0053] The complete construction process for this implementation is as follows: Factory prefabrication: Hollow modules, main beams, and transverse secondary beams are prefabricated according to the 1290mm module, with reserved top tightening grooves 15, pre-embedded nuts 17, welded steel plates, corrugated pipe channels, drainage holes, etc.

[0054] On-site hoisting and support without support: Hoist the modules according to the plan layout, provide temporary support through the support pads 7, and install the reinforcing mold box 6 to form the casting cavity.

[0055] Construction of nodes and joints: Complete the reinforcement anchoring and cast-in-place construction of beam-column node 4 without column cap; select one of the five mid-span joints according to the requirements and complete the module splicing.

[0056] Prestressing tensioning: After the strength of the cast-in-place concrete reaches the standard, the prestressing tendons are tensioned and anchored at the tensioning end, and the tensioning end is grouted and sealed and drained.

[0057] Composite layer pouring and completion: Tie the reinforcing steel bars of the cast-in-place slab, pour a 100mm thick cast-in-place layer, seal and protect all nodes and joints, and finally form a complete, integrally stressed floor structure.

[0058] This embodiment is applicable to conventional large-span public buildings with high requirements for building height, such as shopping malls, office buildings, and libraries. By eliminating column caps, the building height is increased by 15% to 20%; the entire process is support-free and formwork-free, improving construction efficiency by 50% and reducing labor and material costs by 30%; the floor slab self-weight is reduced by 30% to 40%, reducing vertical structural loads; prestressed technology enables large spans of 8 to 24 meters, with low floor slab deflection and excellent crack resistance.

[0059] In another embodiment, the specific implementation of the column-capped floor slab is as follows: Figures 28-35 As shown: Overall Structure and Floor Plan: This embodiment is a heavy-duty prestressed ribbed hollow composite floor slab with column capitals. The overall structure is as follows: Figures 28-30 as well as Figure 31 The plan layout with column caps is shown below: The total dimensions of the floor slab are 23400mm×7800mm, and the column grid is arranged in a 7800mm×8000mm pattern. The frame columns are located at the four corners and the middle, and column caps are installed on the top of each column to form a heavy-duty core area.

[0060] The core components include: precast ribbed hollow modules 1, solid area support plates 10, column caps, reinforcing molds 6, supports 7, prestressed tendons 2, cast-in-place composite layers 3, and five types of mid-span joint structures 5.

[0061] Solid support plates 10 are laid around the column cap to replace the hollow ribbed modules and form a local reinforcement zone; hollow ribbed modules are arranged in the remaining area according to the 1290mm standardized module to form a floor layout of "local reinforcement + overall lightweight"; the frame beams (inverted T-shaped, combined frame composite beams, etc.) are arranged along the column grid and are seamlessly connected with the column caps and solid support plates 10 to jointly bear the heavy load of the floor, which is suitable for underground garages, industrial plants and other scenarios.

[0062] The column cap connection method is as follows Figures 32-34 As shown. The specific construction of the column cap connection is as follows: In this embodiment, the column cap node includes a column cap, a solid area support plate 10, and multiple reinforcements. The column cap is set on the top of the frame column, the solid area support plate 10 is laid in the area of ​​the prefabricated dense rib hollow module 1 around the column cap, and the multiple reinforcements include column cap tie bars 11, horizontal circumferential bars 12, and slab surface reinforcing bars 13.

[0063] Column-capped joints are suitable for heavy-load, large-span applications such as underground parking garages and industrial plants to enhance the punching shear resistance of the column tops. The construction is as follows: Column cap and solid area: A column cap is set at the top of the frame column, and a solid area support plate 10 is laid around the column cap to replace the hollow module, effectively dispersing the concentrated stress at the top of the column and improving the punching shear resistance.

[0064] Multiple reinforcements: The column cap is equipped with column cap tie bars 11 (which connect the beam and column cap in two directions to realize the horizontal force transfer between the beam, cap and column), bottom reinforcement of the column cap plate (resisting the negative bending moment at the top of the column), reinforced steel bars on the surface of the column cap plate (enhancing the bending and crack resistance of the column cap surface layer), and horizontal ring steel bars (restraining the lateral deformation of the column cap concrete), forming a multiple stress skeleton.

[0065] Beam support: The inverted T-shaped frame composite beam and the combined frame composite beam are erected on the column cap and solid area support plate 10. The bottom of the beam is supported by the support pad 7. The outer side of the splice is set with a reinforcing mold box 6 to form a moldless casting cavity.

[0066] Floor slab layers: total thickness 400mm, upper 100mm cast-in-place layer (with one-time cast-in-place column cap slab reinforcement), lower 300mm precast beam / slab layer (including precast column cap section and solid area support plate 10), the cast-in-place column cap and precast components form an integral whole.

[0067] Column capital reinforcement details as follows Figure 35 As shown. The core reinforcement configuration for the cast-in-place column and column capital reinforcement structure is as follows: Column cap tie bar 11: Arranged in both directions, it runs through the column cap and the surrounding frame beams to realize the horizontal force transfer between the beam, cap and column, ensuring the continuity of force.

[0068] Bottom reinforcement of column capital plate: placed at the bottom of the column capital to resist the negative bending moment at the top of the column and improve bending performance.

[0069] One-time casting of column cap slab reinforcement: placed on the top cast-in-place layer of the column cap to enhance the bending and crack resistance of the column cap surface layer, and adapt to the dual effects of prestressing tension and floor load.

[0070] Longitudinal frame beam reinforcement: Concentrated reinforcement at column corners optimizes the stress on the column section and provides reliable support for beam reinforcement anchorage.

[0071] The reinforcement dimensions and spacing shall be in accordance with the design specifications (e.g., 840mm, 420mm, 300mm, etc.) to ensure that the column capital is subjected to uniform stress and that its punching shear and bending shear performance meet the requirements of heavy loads.

[0072] The connection structure between the precast base slab and the frame beam is the same as that without column capitals, but with compatible column capitals. The connection structure between the precast base slab and the frame beam around the column capital is the same as that without column capitals. The key difference is that the solid support plate 10 around the column capital replaces the hollow module, which is seamlessly connected to the column capital. The remaining modules are still supported by the pad 7 and the reinforcing formwork 6 is formwork-free. The gaps between the splices are filled with grout and sealed with mortar / PE rods to ensure the integrity of the floor slab.

[0073] Five types of mid-span joint construction 5 (same as without column capital, suitable for the solid area around the column capital). The core difference between the mid-span joint construction 5 around the column capital and the five types of joints in the floor slab without column capital is that: the module around the column capital is connected to the solid area support plate 10, and the steel bars at the joint are anchored to the reinforcement of the solid area support plate 10, ensuring that the joint, column capital, and solid area support plate 10 form an integral whole, suitable for heavy load requirements.

[0074] Anchorage structure of prestressed tensioning end and transverse secondary beam (same as without column cap): The anchorage structure of prestressed tensioning end with column cap and the anchorage structure of transverse secondary beam and frame beam are the same as those without column cap. Drainage structure 14 (2% drainage slope + drainage hole in bottom slab) works in conjunction with tensioning end and anchorage area to avoid water accumulation and corrosion, and improve the durability of prestressed system and anchorage structure.

[0075] The complete construction process of this embodiment is as follows: Factory prefabrication: Hollow modules, solid area support plates 10, inverted T-shaped / combined frame composite beams are prefabricated according to the 1290mm module, and beam reinforcement, corrugated pipe channels, drainage holes, etc. are reserved.

[0076] On-site support system: The top of the frame column is tied with multiple reinforcements (tie bars, bottom reinforcement, top reinforcement 13, and horizontal ring reinforcement) → Solid area support plate 10 is laid and seamlessly connected with the column cap → Inverted T-shaped frame composite beam and combined frame composite beam are hoisted and erected on the column cap and solid area support plate 10. The bottom of the beam is supported by the support 7 → Reinforcing mold box 6 is installed to close the splice between the column cap and the beam to form the casting cavity.

[0077] Joint and node construction: Select one of the five mid-span joint types to complete the module splicing, and complete the reinforcement anchoring and cast-in-place construction of the column cap and beam.

[0078] Prestressing tensioning: After the concrete strength of the column cap and joint reaches the standard, tension the prestressing tendon 2, grout and seal the corrugated pipe, and drain the accumulated water through the drainage hole.

[0079] Cast-in-place layer pouring and completion: Tie the reinforcing bars of the cast-in-place layer / column cap slab, pour a 100mm thick cast-in-place layer to form an integral load-bearing structure and complete the floor slab construction.

[0080] This embodiment is applicable to heavy-duty scenarios with high requirements for floor load-bearing capacity, such as underground parking garages, industrial plants, and warehousing and logistics centers. By combining column capitals with solid support plates (10 units), the punching shear resistance of the column top is increased by more than 60%, meeting heavy-duty requirements; multiple reinforcements enhance the stiffness and integrity of the column capitals, preventing punching shear damage; the entire process requires no supports or formwork, increasing construction efficiency by 50% and reducing the floor slab's self-weight by 30%~40%, simultaneously meeting the dual requirements of heavy load-bearing capacity and lightweight construction.

[0081] Those skilled in the art can flexibly choose between floor slab systems with or without column capitals, based on project requirements, and select from the five types of mid-span joint constructions as needed: For projects with high clearance requirements and conventional loads: prioritize floor slabs without column caps + bolted joints / wedge-shaped cement blocks 19 joints, balancing clearance and construction efficiency.

[0082] For projects with high load-bearing capacity and heavy loads: prioritize the use of floor slabs with column caps + welded steel plate rigid joints / cast-in-place micro-expansion concrete with tight joints to ensure structural safety and durability.

[0083] For projects with extremely high requirements for joint tightness: prioritize cast-in-place micro-expansion concrete to tighten the joints, ensuring a tight and compact joint with excellent crack resistance and sealing.

[0084] Secondly, embodiments of the present invention also disclose a construction method for a prestressed ribbed hollow composite floor slab that requires no support or formwork, used to fabricate the aforementioned prestressed ribbed hollow composite floor slab, such as... Figure 36 As shown, it includes the following steps: S1. Factory-prefabricated dense rib hollow module 1, with prestressed tendon 2 channels and splicing structure reserved inside the module; S2. The precast ribbed hollow module 1 is hoisted on site, and the module is temporarily supported by the support 7. The reinforcing mold box 6 is installed on the outside of the module to form the casting cavity. S3. The mid-span joint structure 5 is used to complete the splicing of adjacent precast ribbed hollow modules 1, and at the same time, the reinforcement binding and closure of beam-column node 4 are completed. S4. Pour the cast-in-place concrete for beam-column joint 4 and mid-span joint. After the concrete strength reaches the design requirements, tension the prestressing tendon 2 and complete the anchorage. S5. Pour the upper cast-in-place composite layer 3, seal and protect the nodes and joints, and complete the floor slab construction.

[0085] The streamlined process enables industrialized construction without supports or formwork, reducing wet work and the use of reusable materials. Standardized joint and node construction and prestressing tensioning sequence ensure the integrity and load-bearing performance of the floor slab, significantly shortening the construction period and reducing costs.

[0086] Preferably, in step S3, when the beam-column node 4 adopts a node without column cap, it is necessary to first embed a steel structure bracket 8 on the side of the frame column, and then erect the precast composite beam 9 on the steel structure bracket 8 and complete the reinforcement anchoring. In step S3, when the beam-column node 4 adopts a node with a column cap, the column cap should be tied with multiple reinforcements first, the solid area support plate 10 should be laid, and then the splicing of the precast ribbed hollow module 1 should be completed.

[0087] Preferably, in step S4, after the prestressing tendon 2 is tensioned, the tensioning end of the prestressing tendon 2 is grouted and sealed, and drainage is completed at the tensioning end through the drainage holes in the bottom slab. The combination of grouting and sealing at the tensioning end and drainage treatment both fixes the prestressing tendon 2 and prevents water accumulation and corrosion. This improves the durability of the prestressing system, ensures long-term stable operation of the tendons, and extends the service life of the floor slab.

[0088] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention is not limited to the specific combination of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. A prestressed, densely ribbed, hollow composite floor slab that requires no support or formwork, characterized in that... The system includes precast ribbed hollow modules, prestressed tendons, cast-in-place composite layers, beam-column joints, and mid-span joint structures. Each precast ribbed hollow module has a reinforcing mold, which replaces traditional formwork to form the casting cavity. The bottom of each precast ribbed hollow module is temporarily supported by supports, which replace full-span scaffolding for support-free construction. The prestressed tendons pass through reserved channels within the precast ribbed hollow modules. The cast-in-place composite layer is cast above the precast ribbed hollow modules and forms an integral load-bearing structure with them. The beam-column joints are available in two structural forms: with and without column caps. The mid-span joint structure is used for splicing adjacent precast ribbed hollow modules.

2. The prestressed ribbed hollow composite floor slab without support or formwork as described in claim 1, characterized in that, The mid-span joint structure can be any one of the following: cast-in-place micro-expansion concrete tightening joint, bolt and nut tightening joint, wedge-shaped cement block tightening joint, or welded steel plate rigid joint.

3. The prestressed dense-ribbed hollow composite floor slab without support or formwork as described in claim 2, characterized in that, The bolt and nut tightening joint can be either a bolt unscrew tightening joint or a bolt tightening tightening joint.

4. The prestressed dense-ribbed hollow composite floor slab without support or formwork as described in claim 1, characterized in that, The column-cap-less node includes a steel corbel, a precast composite beam, and a cast-in-place node area. The steel corbel is embedded in the side of the frame column, the precast composite beam is erected on the steel corbel, and the cast-in-place node area is cast at the junction of the precast composite beam and the frame column to form a rigid connection.

5. The prestressed ribbed hollow composite floor slab without support or formwork as described in claim 1, characterized in that, The column-capped node includes a column cap, a solid area support plate, and multiple reinforcements. The column cap is set on the top of the frame column, the solid area support plate is laid in the prefabricated ribbed hollow module area around the column cap, and the multiple reinforcements include column cap tie bars, horizontal circumferential bars, and slab surface reinforcement bars.

6. The prestressed ribbed hollow composite floor slab without support or formwork as described in claim 1, characterized in that, The reinforcing mold box is provided with a drainage structure, which includes a drainage slope and drainage holes in the bottom plate. The drainage holes in the bottom plate penetrate the bottom plate of the prefabricated ribbed hollow module.

7. The prestressed ribbed hollow composite floor slab without support or formwork as described in claim 1, characterized in that, The prefabricated ribbed hollow modules are laid out using a standardized 1290mm module, with a 10mm-20mm splicing gap reserved at the edges of the modules.

8. A construction method for a prestressed, densely ribbed, hollow composite floor slab that requires no support or formwork, characterized in that... The method for manufacturing a prestressed, ribbed, hollow composite floor slab without support or formwork as described in any one of claims 1-7 includes the following steps: S1. Factory-prefabricated dense rib hollow modules, with prestressed tendon channels and splicing structures reserved inside the modules; S2. The prefabricated ribbed hollow modules are hoisted on site, and temporary support is provided for the modules using supports. Reinforcing molds are installed on the outside of the modules to form a casting cavity. S3. The mid-span joint structure is used to complete the splicing of adjacent prefabricated ribbed hollow modules, and at the same time, the reinforcement binding and closure of the beam-column joint are completed. S4. Pour the cast-in-place concrete in the beam-column joint area and mid-span joint. After the concrete strength reaches the design requirements, tension the prestressed tendons and complete the anchorage. S5. Pour the upper cast-in-place composite layer, seal and protect the joints and seams, and complete the floor slab construction.

9. The construction method of the prestressed dense-ribbed hollow composite floor slab without support or formwork as described in claim 8, characterized in that, In step S3, when the beam-column joint adopts a joint without column cap, it is necessary to first embed a steel structure corbel on the side of the frame column, and then erect the precast composite beam on the steel structure corbel and complete the reinforcement anchoring. In step S3, if the beam-column joint uses a column cap joint, the column cap should be tied with multiple reinforcements first, a solid area support plate should be laid, and then the splicing of the precast ribbed hollow modules should be completed.

10. The construction method of the prestressed dense-ribbed hollow composite floor slab without support or formwork as described in claim 8, characterized in that, In step S4, after the prestressing tendon is tensioned, the tensioning end of the prestressing tendon is grouted and sealed, and the drainage of the tensioning end is completed through the drainage hole of the bottom plate.

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