A large-span prefabricated ribbed prestressed hollow bidirectional composite slab

Abstract

The present invention proposes a large-span prefabricated ribbed prestressed hollow bidirectional composite slab, comprising a prefabricated bottom plate, longitudinal ribs and transverse ribs and a post-cast layer, wherein the longitudinal ribs and transverse ribs are staggered on the bottom plate to form a grid with a light filling block; prestressed steel strands are arranged in the longitudinal direction in the longitudinal ribs, and a steel mesh composed of longitudinal and transverse steel bars is arranged in the bottom plate and below the prestressed steel strands; a plurality of shear steel bars are embedded in the longitudinal ribs and transverse ribs and protrude from their respective upper surfaces, and in the bottom plate and protrude from the upper surface of the light filling block, and a grouting hole is preset at the position where the shear steel bars are provided in the light filling block; connecting steel bars overlapped with the transverse steel bars in the adjacent bottom plate are provided in the joint area, and longitudinal through-length structural steel bars are provided; and upper steel bars of the composite plate are provided in the post-cast layer. The present invention has light self-weight, no anti-arch, is suitable for bidirectional plates, ensures coordinated work between the post-cast layer and the prefabricated plate, does not require formwork in the joint area, and does not require post-tensioned prestressed steel bars, has reliable structural force, and has high construction efficiency.

Description

Technical Field

[0001] The invention relates to a prefabricated concrete hollow floor structure, in particular to a large-span prefabricated ribbed prestressed hollow bidirectional composite slab, and belongs to the field of general assembled building structures. Background Art

[0002] In recent years, my country has accelerated the transformation and upgrading of the construction industry. Prefabricated buildings have entered a rapid development stage due to their advantages such as high degree of industrialization, reliable construction quality, high construction efficiency, energy saving and environmental protection. The development of prefabricated buildings has become a national policy for the development and reform of my country's construction industry.

[0003] According to the Technical Code for Prefabricated Concrete Structures JGJ1-2014, ordinary truss reinforced concrete composite slabs should be used for composite floors with a span of less than 6m. However, for floors with a span greater than 6m, since the deflection of the slab or the crack width often plays a controlling role, the use of solid composite floors can only be solved by increasing the thickness of the slab, resulting in heavy self-weight of the slab, poor seismic performance, and low comprehensive economic indicators. To solve such problems of large-span floors, the commonly used technical measures are to apply prestress and set hollows. Applying prestress can significantly improve the bending stiffness of the composite slab, and setting hollows can effectively reduce the self-weight of the composite slab. The combination of the two has a better effect.

[0004] In 2008, Dou Lijun proposed the "Large-span Prestressed Hollow Composite Slab" (CN201206293Y), the main technical solution of which is to apply prestress in the precast slab to improve the overall rigidity, bury steel trusses to improve the bonding force between the precast slab and the post-cast layer, and add hollow tubes in the post-cast layer to reduce the deadweight. This solution has the following shortcomings: the precast slab is a solid slab, and when used for large-span floor slabs, it has a large deadweight and is inconvenient to transport and hoist; in addition, since the thickness of the post-cast layer concrete is generally not large (about 6cm), in order to achieve the weight reduction effect, the diameter of the hollow tube cannot be too small, and the weakening of the post-cast concrete at the position of the hollow tube is more obvious, which is easy to be damaged.

[0005] In 2014, Yang Feng proposed the "prestressed hollow slab composite floor" (CN203905239U), whose structure includes: prestressed hollow slab, prestressed precast beam and cast-in-place concrete composite layer, wherein the prestressed hollow slab is provided with a number of through holes in the longitudinal direction, prestressed steel strands are buried in the longitudinal direction at the bottom, and steel mesh and tie bars are arranged in the slab joints to improve the integrity of the slab. The shortcomings are: the connection performance between adjacent precast slabs is poor, and it is only applicable to one-way slabs; the prestressed steel strands are located at the bottom of the slab, far away from the neutral axis, and the anti-arch value of the precast slab after tensioning is large, which seriously affects the transportation and installation of the components.

[0006] In 2017, Xu Yan and others proposed "A Prestressed Hollow Composite Slab" (CN107313539A). The technical solution adopted is: the prefabricated bottom plate is long and narrow, prestressed steel wires are arranged along the longitudinal direction of the bottom plate, transverse steel bars are arranged under the prestressed steel wires, lightweight filling parts are used on the upper part of the prefabricated bottom plate, and solid concrete ribs are arranged between adjacent filling parts. The transverse steel bars between the prefabricated bottom plates overlap each other in the joint area to form a hollow bidirectional composite slab. Its main deficiencies are: 1. The post-cast concrete layer within the range of the lightweight filling parts and the prefabricated base plate are connected by grouting only through a vertical hole, and the in-plane shear resistance is seriously insufficient, and the two cannot work together; 2. The width of the post-cast strip in the joint of the prefabricated plate is only 100-200mm, which cannot meet the lap length LaE requirement of the transverse steel bars (diameter of at least 8mm), and the transverse force transmission is affected; 3. The joint position of the prefabricated plate requires formwork to cast concrete, which is inconvenient to construct and does not conform to the development direction of formwork-free prefabricated buildings; 4. Post-tensioned prestressed steel bars are set at the joints of the prefabricated plates, which increases the on-site construction process.

[0007] In 2019, Tian Jian et al. proposed "A ribbed prefabricated prestressed hollow composite floor and its construction method" (CN110029762A), the main structure of which is: prefabricated ribbed plates with prestressed steel strands embedded in the ribs, and lightweight fillers in the cavities between the ribs. The shortcomings are: no connection between adjacent prefabricated plates, only applicable to one-way plates; only longitudinal ribs are set, the overall stiffness of the prefabricated plates is small, and they are prone to cracking during hoisting.

[0008] In summary, the existing technology of large-span composite floor slabs mainly has the following defects: 1. The prefabricated panels are heavy and difficult to transport and hoist; 2. The connection performance between adjacent prefabricated panels is poor, which is not suitable for two-way panels; 3. The anti-arch of the prefabricated panels is large, which affects transportation and installation; 4. The collaborative performance between the post-casting layer and the prefabricated panels within the lightweight filling block is poor; 5. The joint area of ​​the prefabricated panels requires formwork to cast concrete or post-tensioned prestressed steel bars, which increases the difficulty of construction. Therefore, the development of a large-span composite floor slab technology that solves the above defects has become an urgent problem to be solved in the current prefabricated composite floor slabs. Summary of the invention

[0009] The purpose of the present invention is to solve the problems of heavy self-weight of precast panels, poor connection performance between adjacent precast panels and not suitable for two-way panels, large anti-arch of precast panels, poor cooperative working performance between the post-cast layer and the precast panels in the range of lightweight filling blocks, and complicated construction caused by the need to support formwork for pouring concrete or post-tensioning prestressed steel bars in the joint area of ​​the precast panels. A large-span precast ribbed prestressed hollow two-way composite panel is proposed. The present invention has the advantages of light self-weight, no anti-arch, suitable for two-way panels, guaranteed cooperative work between the post-cast layer and the precast panel, no need for formwork in the joint area and no post-tensioning prestressed steel bars.

[0010] To achieve the above object, the present invention adopts the following technical solution:

[0011] The present invention proposes a large-span prefabricated ribbed prestressed hollow bidirectional composite slab, comprising a prefabricated ribbed slab at the bottom and a post-cast layer at the top; the characteristic is that the prefabricated ribbed slab comprises a prefabricated bottom plate, longitudinal ribs and transverse ribs, the longitudinal ribs and transverse ribs are staggered on the bottom plate to form a grid, and a lightweight filling block is arranged in the grid; prestressed steel strands are arranged in the longitudinal direction in the longitudinal ribs, and a steel mesh composed of longitudinal steel bars and transverse steel bars is arranged in the bottom plate, and the steel mesh is located below the prestressed steel strands, the longitudinal steel bars extend out of the bottom plate in the horizontal direction by a length of ≧100mm, and the transverse steel bars are bent upward at the edge of the bottom plate and extend out by a length of ≧100mm; between the longitudinal ribs and A plurality of shear steel bars are uniformly embedded in the transverse ribs and protrude from their respective upper surfaces, and in the bottom plate and protrude from the upper surface of the lightweight filling block, and leakage holes for realizing integral pouring of concrete are preset at the positions where the shear steel bars are provided in the lightweight filling block; first connecting steel bars are provided on the upper surfaces of two adjacent bottom plates, which are overlapped with the transverse steel bars in the adjacent bottom plates respectively, and second connecting steel bars are provided on the upper surface of the bottom plate located at the edge of the transverse support, and the second connecting steel bars and the longitudinal steel bars extending out of the edge of the bottom plate are anchored in the corresponding supports respectively, and through-length structural steel bars are respectively provided in the longitudinal direction within the length range of the first connecting steel bar and the second connecting steel bar; the upper steel bars of the composite plate and the post-cast concrete are provided in the post-cast layer.

[0012] The characteristics and beneficial effects of the present invention are:

[0013] The present invention embeds shear steel bars on the upper surface of the longitudinal ribs and transverse ribs and in the bottom plate within the range of the lightweight filling blocks to ensure the coordinated work between the post-cast concrete layer and the prefabricated ribbed plate. The shear steel bars within the range of the lightweight filling blocks are positioned to achieve the overall pouring of concrete by presetting the leakage holes in the lightweight filling blocks to ensure that the shear steel bars play a role. In order to improve the shear resistance, the shear steel bars in the lightweight filling blocks are arranged in different directions, and a rough surface is arranged on the upper surface of the bottom plate outside the range of the longitudinal ribs;

[0014] In the present invention, the prefabricated ribbed plate adopts the method of setting connecting steel bars in the joint area, and the connecting steel bars and the corresponding bottom plate transverse steel bars are overlapped with the same diameter and equal spacing, and the overlap length meets the requirements of the specification for the overlap length LaE, which can ensure the transverse force transmission and is suitable for two-way plates;

[0015] In the present invention, the prefabricated ribbed plate is seamlessly spliced ​​in the joint area, and the bottom plate is also used as a template for pouring concrete in the joint area, so that the template can be free of support;

[0016] The present invention only arranges the prestressed steel strands within the longitudinal ribs of the prefabricated ribbed plate, and the prestressed steel strands are tensioned in the factory by the pre-tensioning method, thus avoiding the tensioning process on the construction site;

[0017] The present invention arranges the prestressed steel strands within the range of the longitudinal ribs and at the centroid of the prefabricated ribbed slab, so that the prefabricated ribbed slab is always in an axially compressed state before the concrete is poured, thereby preventing the prefabricated ribbed slab from arching.

[0018] In order to improve the rigidity of the prefabricated ribbed plate, the present invention sets longitudinal ribs and transverse ribs in two directions, so that it has good transportation and hoisting performance. At the same time, in order to reduce the weight of the prefabricated ribbed plate, the transverse ribs outside the range of the longitudinal ribs are made into variable heights.

[0019] The prefabricated ribbed plate of the present invention can preset pipeline holes on the sides of the longitudinal ribs and the transverse ribs, which is convenient for laying pipelines;

[0020] The width of the prefabricated ribbed slab of the present invention is in the range of 1500-3000 mm. Generally, only 3 to 4 ribbed slabs are needed to assemble a large-span composite floor, and the construction efficiency is high.

[0021] The bottom plate concrete thickness of the prefabricated ribbed plate in the present invention is only 50-60mm, and the height of the longitudinal ribs and transverse ribs is 70-90mm, which greatly reduces the self-weight of the prefabricated ribbed plate. Taking a span of 9m, a bottom plate thickness of 60mm, and a rib height of 90mm as an example, the prefabricated ribbed plate weighs only 4 tons, which is convenient for transportation and hoisting.

[0022] In summary, the present invention proposes a large-span prefabricated ribbed prestressed hollow two-way composite slab, which has light weight, no anti-arch, is suitable for two-way slabs, ensures coordinated work between the post-cast layer and the prefabricated slab, does not require formwork in the joint area, and does not require post-tensioned prestressed steel bars. The structure is reliable and has high construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is an overall plan view of a composite plate according to an embodiment of the present invention;

[0024] Figure 2 yes Figure 1 AA section diagram of the middle laminated plate;

[0025] Figure 3 is a plan view of a single prefabricated ribbed plate in the composite plate of the present invention;

[0026] Figure 4 yes Figure 3 BB section of the precast ribbed slab;

[0027] Figure 5 It is a detailed partial cross-sectional view of the composite board of the present invention, and the structure not shown on the right side of the figure is shown on the left side of the figure;

[0028] Figure 6 yes Figure 5 A partial large-scale drawing of the middle joint area;

[0029] Figure 7 yes Figure 5A partial large-scale drawing of medium-lightweight infill blocks;

[0030] Figure 8 yes Figure 5 Partial detail drawing of the middle transverse support;

[0031] Fig. 9 yes Figure 3 CC section of the precast ribbed slab.

[0032] In the figure: 1. Prefabricated ribbed slab; 2. Post-cast layer; 3. Bottom plate; 4. Longitudinal ribs; 5. Transverse ribs; 6. Prestressed steel strands; 7. Longitudinal reinforcement; 8. Transverse reinforcement; 9. Lightweight filling block; 10. Shear reinforcement; 11. Leakage hole; 12. Joint area; 13a. First connecting reinforcement; 13b. Second connecting reinforcement; 14. Full-length structural reinforcement; 15. Support; 16. Upper reinforcement; 17. Pipeline hole. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0034] In order to better understand the present invention, an application example of a large-span prefabricated ribbed prestressed hollow bidirectional composite slab proposed by the present invention is described in detail below.

[0035] exist Figure 1-Figure 8In the embodiment shown, the composite slab is composed of a prefabricated ribbed slab 1 at the bottom and a post-cast layer 2 at the top. The prefabricated ribbed slab 1 includes a prefabricated bottom slab 3, longitudinal ribs 4 and transverse ribs 5. The longitudinal ribs 4 and transverse ribs 5 are staggered on the bottom slab 3 to form a grid, and a lightweight filling block 9 is arranged in the grid; there is a joint area 12 between two adjacent bottom slabs 3. Prestressed steel strands 6 are arranged longitudinally within the range of the longitudinal ribs 4. The prestressed steel strands 6 use low-relaxation steel strands (satisfying the requirement that the stress relaxation rate is not greater than 2.5% after 1000 hours). A steel mesh composed of longitudinal steel bars 7 and transverse steel bars 8 is arranged within the range of the bottom slab 3, and the steel mesh is located below the prestressed steel strands 6. The longitudinal steel bars 7 extend horizontally from the bottom slab 3 by a length of ≧100 mm, and the transverse steel bars 8 are bent upward at the edge of the bottom slab 3 to extend by a length of ≧100 mm. A plurality of shear steel bars 10 are uniformly embedded in the longitudinal ribs 4 and transverse ribs 5 and protrude from their respective upper surfaces, and in the bottom plate 3 and protrude from the upper surface of the lightweight filling block 9, and a grouting hole 11 is preset at the position where the shear steel bars 10 are provided in the lightweight filling block 9 to realize the integral pouring of concrete. A first connecting steel bar 13a is arranged on the upper surface of two adjacent bottom plates 3 in the joint area 12, and is overlapped with the transverse steel bars 8 in the adjacent bottom plates respectively to realize the transverse force transmission; a second connecting steel bar 13b is arranged on the upper surface of the bottom plate 3 located at the edge of the transverse support, and the second connecting steel bar 13b and the longitudinal steel bar 7 extending from the edge of the bottom plate 3 are anchored in the corresponding support respectively; and a through-length structural steel bar 14 is respectively arranged in the longitudinal direction within the length range of the first connecting steel bar 13a and the second connecting steel bar 13b. The upper steel bars 16 of the composite plate are tied, and the concrete of the post-casting layer 2 is poured to form the composite plate.

[0036] exist Figure 3 , Figure 4 , Figure 5 , Figure 7 In the embodiment shown, multiple shear steel bars 10 are uniformly embedded in the longitudinal ribs 4 and transverse ribs 5 and protrude from their respective upper surfaces, and in the bottom plate 3 and protrude from the upper surface of the lightweight filling block 9, so as to ensure the coordinated work between the concrete of the post-cast layer 2 and the prefabricated ribbed plate 1. The shear steel bars 10 within the lightweight filling block 9 are positioned to realize the integral pouring of concrete by presetting the leakage holes 11 in the lightweight filling block 9, so as to ensure that the shear steel bars 10 play a role. In order to improve the shear resistance, the shear steel bars 10 in the lightweight filling block 9 are arranged along different directions, such as Figure 3 In the prefabricated ribbed plate 1 in the range shown, the shear reinforcement 10 arranged in the lightweight filling block 9 has a transverse direction and a longitudinal direction. A rough surface is arranged on the upper surface of the bottom plate 3 outside the range of the longitudinal rib 4. The spacing of the longitudinal ribs 4 in the prefabricated ribbed plate 1 is 500-700mm, the spacing of the transverse ribs 5 is 1000-1500mm, and the diameter and spacing of the shear reinforcement 10 are determined according to the design.

[0037] exist Figure 5 , Figure 6 , Figure 8 In the illustrated embodiment, a first connecting steel bar 13a is provided on the upper surfaces of two adjacent bottom plates 3 in the joint area 12, and a second connecting steel bar 13b is provided on the upper surface of the bottom plate 3 located at the edge of the transverse support. The connecting steel bars 13a and 13b are overlapped with the corresponding bottom plate transverse steel bars 8 with the same diameter and equal spacing, and the overlap length meets the requirements of the specification for the overlap length LaE, which can ensure transverse force transmission and is suitable for two-way plates.

[0038] exist Figure 2 , Figure 5 , Figure 6 In the illustrated embodiment, the bottom plates 3 of two adjacent prefabricated ribbed plates 1 are seamlessly spliced ​​in the joint area 12, and the bottom plate 3 also serves as a template for pouring concrete in the joint area 12, thereby achieving the goal of eliminating the need for supporting templates.

[0039] exist Figure 4 , Figure 5 , Figure 6 In the illustrated embodiment, the prestressed steel strands 6 are arranged only within the longitudinal ribs 4 of the prefabricated ribbed slab 1, and the pre-tensioning method is adopted for factory tensioning, thereby avoiding the tensioning process at the construction site. Preferably, the prestressed steel strands 6 are arranged within the longitudinal ribs 4 and at the centroid of the prefabricated ribbed slab 1, so that the prefabricated ribbed slab 1 is always in an axially compressed state before the concrete is poured, thereby preventing the prefabricated ribbed slab 1 from arching back.

[0040] exist Figure 3 , Fig. 9 In the illustrated embodiment, in order to improve the rigidity of the prefabricated ribbed plate 1, longitudinal ribs 4 and transverse ribs 5 are arranged in two directions, so that the prefabricated ribbed plate 1 has good transportation and lifting performance. At the same time, in order to reduce the weight of the prefabricated ribbed plate 1, the transverse ribs 5 outside the range of the longitudinal ribs 4 are made into variable heights.

[0041] exist Fig. 9 In the illustrated embodiment, the prefabricated ribbed plate 1 may have pipeline holes 17 preset on the sides of the longitudinal ribs 4 and the transverse ribs 5 to facilitate the laying of pipelines.

[0042] exist Figure 1 , Figure 2 In the illustrated embodiment, the width of the prefabricated ribbed slab 1 is in the range of 1500-3000 mm, and generally only 3 to 4 ribbed slabs are needed to assemble a large-span composite floor, thus achieving high construction efficiency.

[0043] exist Figure 3 , Figure 4 In the illustrated embodiment, the concrete thickness of the bottom plate 3 of the prefabricated ribbed slab 1 is only 50-60 mm, and the heights of the longitudinal ribs 4 and transverse ribs 5 are 70-90 mm, which greatly reduces the deadweight of the prefabricated ribbed slab 1. Taking a span of 9 m, a bottom plate 3 with a thickness of 60 mm, and a height of 90 mm of the longitudinal ribs 4 and transverse ribs 5, for example, the deadweight of the prefabricated ribbed slab 1 is only 4 tons, which is convenient for transportation and hoisting.

[0044] Furthermore, a method for manufacturing a large-span prefabricated ribbed prestressed hollow bidirectional composite slab according to an embodiment of the present invention is as follows: (1) a prefabricated ribbed slab 1 is manufactured in a factory according to a processing drawing, including a prefabricated bottom plate 3, longitudinal ribs 4 and transverse ribs 5. First, the prestressed steel strands 6 and the steel mesh composed of longitudinal steel bars 7 and transverse steel bars 8 are arranged on a mold platform. Then, the prestressed steel strands 6 are tensioned to control the tension stress. After that, the concrete of the prefabricated bottom plate 3, longitudinal ribs 4 and transverse ribs 5 is integrally poured. When the compressive strength of the concrete cube reaches more than 75% of the strength design value, the prestressed steel strands 6 are released; (2) the prefabricated ribbed slab 1 is transported to The prefabricated ribbed slab is hoisted to the designated location at the construction site, a first connecting steel bar 13a is set in the joint area 12, and a second connecting steel bar 13b is set at the edge of the transverse support of the composite slab. The first connecting steel bar 13a and the second connecting steel bar 13b are overlapped with the corresponding transverse steel bars 8 of the bottom plate at the same diameter and spacing, and full-length structural steel bars 14 are respectively set in the longitudinal direction within the length range of the first connecting steel bar 13a and the second connecting steel bar 13b; (3) The longitudinal steel bars 7 of the prefabricated ribbed slab 1 and the connecting steel bars 13b at the edge of the composite slab are respectively anchored into the corresponding supports 15 of the circumference, the upper steel bars 16 of the composite slab are tied, and the concrete of the post-casting layer 2 is poured to form the composite slab. Since the prefabricated ribbed slab 1 adopts seamless splicing in the joint area 12, the bottom plate 3 can also be used as a template to achieve the support-free template.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A large-span prefabricated ribbed prestressed hollow bidirectional composite slab, comprising a prefabricated ribbed slab at the bottom and a post-cast layer at the top; characterized in that: The prefabricated ribbed plate comprises a prefabricated bottom plate, longitudinal ribs and transverse ribs, wherein the longitudinal ribs and transverse ribs are staggered on the bottom plate to form a grid, and a lightweight filling block is arranged in the grid; a prestressed steel strand is arranged in the longitudinal direction in the longitudinal rib, and a steel mesh composed of longitudinal steel bars and transverse steel bars is arranged in the bottom plate, and the steel mesh is located below the prestressed steel strand, the longitudinal steel bars extend out of the bottom plate in the horizontal direction by a length of ≧100mm, and the transverse steel bars are bent upward at the edge of the bottom plate and extend out by a length of ≧100mm; A plurality of shear steel bars are uniformly embedded in the longitudinal ribs and transverse ribs and protrude from their respective upper surfaces, and in the bottom plate and protrude from the upper surface of the lightweight filling block, and a grouting hole for realizing integral concrete pouring is preset at the position where the shear steel bars are provided in the lightweight filling block; a first connecting steel bar is provided on the upper surface of two adjacent bottom plates, which is overlapped with the transverse steel bars in the adjacent bottom plates respectively, a second connecting steel bar is provided on the upper surface of the bottom plate located at the edge of the transverse support, the second connecting steel bar and the longitudinal steel bar extending out of the edge of the bottom plate are anchored in the corresponding support respectively, and full-length structural steel bars are respectively provided in the longitudinal direction within the length range of the first connecting steel bar and the second connecting steel bar; the upper steel bars of the composite plate and the post-cast concrete are provided in the post-cast layer; Each connecting steel bar is overlapped with the corresponding bottom plate transverse steel bar with the same diameter and equal spacing, and the overlap length meets the requirements of the specification for the overlap length LaE; Adjacent prefabricated base plates are joined seamlessly.

2. The large-span prefabricated ribbed prestressed hollow bidirectional composite slab according to claim 1 is characterized in that: The shear-resistant steel bars in the bottom plate and protruding from the upper surface of the lightweight filling block are arranged in different directions, and a rough surface is arranged on the upper surface of the bottom plate outside the range of the longitudinal ribs.

3. The large-span prefabricated ribbed prestressed hollow bidirectional composite slab according to claim 1 is characterized in that: The prestressed steel strands are arranged only within the range of the longitudinal ribs, and the prestressed steel strands are tensioned in a factory by using a pre-tensioning method.

4. The large-span prefabricated ribbed prestressed hollow bidirectional composite slab according to claim 1 is characterized in that: The prestressed steel strands are arranged at the centroid position of the prefabricated ribbed plate.

5. The large-span prefabricated ribbed prestressed hollow bidirectional composite slab according to claim 1 is characterized in that: The longitudinal ribs and transverse ribs are arranged in two directions, and the transverse ribs located outside the range of the longitudinal ribs are transverse ribs with variable height.

6. The large-span prefabricated ribbed prestressed hollow bidirectional composite slab according to claim 1 is characterized in that: The prefabricated ribbed plate has preset pipeline holes on the sides of the longitudinal ribs and the transverse ribs.

7. The large-span prefabricated ribbed prestressed hollow bidirectional composite slab according to any one of claims 1 to 6, characterized in that: The width of the prefabricated ribbed plate is 1500-3000 mm, the thickness of the bottom plate is 50-60 mm, and the heights of the longitudinal ribs and transverse ribs are 70-90 mm respectively.

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