Combined hollow floor support plate

Abstract

The utility model discloses a combined hollow floor support plate. The combined hollow floor support plate comprises a bottom plate, a box body and a connecting piece, the length of the bottom plate is the span of the floor system, and the width is multiple of a plurality of box bodies; the plurality of box bodies are longitudinally arranged and fixed at intervals on the bottom plate; the box bodies are connected through connecting pieces in the longitudinal direction. And the three components form a combined hollow floor support plate for bearing during floor system construction, and also serve as a template of post-pouring concrete and a bottom surface protection layer of the post-pouring concrete. A plurality of hollow floor bearing plates are transversely and closely spliced and fully paved on floor cover plate spans, gaps among the box bodies are paved with steel bars, concrete is poured later to form bidirectional floor cover ribbed beams, concrete is poured later on the top surfaces of the box bodies to form inter-rib panels, and the building floor cover meeting the using function bearing requirement is formed. The utility model is suitable for medium and large span floor systems, has the advantages of simple manufacture, low cost, no formwork and support, fast and convenient construction, light floor system dead weight, complete bidirectional stress, excellent mechanical property and the like, and meets the key index of'double saving 'of steel bar consumption and concrete consumption compared with the traditional cast-in-place beam slab floor system.

Description

Technical Field

[0001] The utility model relates to the technical field of assembled building structures, and more specifically to a combined hollow floor decking plate. Background Art

[0002] With the development of my country's economy and technology, as well as the rise in labor costs, the development of building industrialization and assembly is a national industrial policy. However, while prefabricated buildings generally seek to reduce on-site workload (formwork, steel bar binding, concrete pouring), they are accompanied by inconvenience in hoisting and installation, difficulty in steel bar joints and difficulty in ensuring quality, and especially increase in the amount of steel bars and concrete, which increases project costs, reducing the overall advantages of prefabricated buildings and affecting their popularization and application. Prefabricated buildings are currently driven more by industrial policies and still lack the inherent advantages of fast speed and low cost. The market is more in need of new and advantageous technologies.

[0003] Among the four types of components, namely beams, columns, walls and slabs, floor slabs (or floor slabs) are the key areas of prefabricated development because of the large workload of on-site formwork, steel bar binding and concrete pouring, and the fact that they do not directly bear the effects of earthquakes, so the requirements for end steel bar connections are relatively low.

[0004] For example, a prestressed concrete truss composite slab is disclosed in the utility model patent (authorization announcement number CN 205653944 U, authorization announcement date 2016.10.19). According to the technical parameters of the standard atlas "Prestressed Concrete Steel Tube Truss Composite Slab L22ZG401" corresponding to the patent, it can be seen that this technology has advantages for small-span slabs (such as less than 5m), but lacks advantages for medium and large-span slabs commonly seen in engineering (such as more than 8m). Specifically, it is reflected in: ① The thickness is large and the deadweight is heavy. The thickness of the 8.1m span floor slab is 0.22m, which is greater than the thickness of the cast-in-place beam-slab floor slab of about 0.2m; ② It is a one-way slab, which reduces the economy of the floor slab; ③ The steel tube truss is only used for construction purposes, which increases the cost, and the large-span slab is insufficient in rigidity and still requires construction support;

[0005] The utility model patent (authorization announcement number CN 113089920 B, authorization announcement date 2022.02.18) discloses a steel tube truss prestressed concrete composite slab. In order to reduce the self-weight, a hollow slab inner mold is placed in the post-cast surface layer. However, due to the influence of the steel truss, the hollow ratio is not high and the self-weight reduction is limited. It also belongs to a unidirectional force, which limits its economic efficiency.

[0006] A utility model patent (authorization announcement number: CN 218562705 U, authorization announcement date: March 3, 2023) discloses a precast floor slab. To reduce the self-weight of large-span slabs, a precast floor slab with reserved cavities is adopted, and plastic formwork is added in the post-cast composite layer to form a hollow slab. The length and width of the precast floor slab are generally 2m - 3m, and the floor slabs with spans above 8m are spliced longitudinally and transversely. Due to the splicing of multiple slabs, construction support is required. Since there are cast-in-place rib beams at the splicing joints, formwork support is still needed. Especially, the stress bars penetrate through the precast floor slab and need to be connected at the splicing joints. The joints all over the floor slab do not reduce the on-site workload and also reduce the reliability of the floor slab.

[0007] A utility model patent application (application publication number: CN 112144724 A, application publication date: December 29, 2020) discloses a closely-spaced hollow composite slab, which adopts longitudinally precast in one span and transversely closely-spaced precast hollow bottom slabs. Its advantage is to avoid the connection of longitudinal stress bars at the bottom of the slab, reduce the on-site workload and increase the reliability. However, the transverse bottom bars are not continuous, and it is still in a one-way slab stress state. The lightweight filler for forming cavities in the post-cast composite layer, such as lightweight plastic formwork and foam, is not environmentally friendly, and other materials will increase the self-weight. The rib beam of this structure (excluding the about 5cm thick integral cast-in-place surface layer) is precast integrally with the bottom slab to form an inverted T-shaped cross-section, and its stiffness does not meet the stress requirements during the construction stage (other types need to be reinforced with steel truss to increase the stiffness), and it still cannot achieve support-free.

[0008] The inventor of the utility model proposed the "stress island" design theory for slab floors and hollow slab floors in 2005 (Xie Jingzhong, Mechanical properties and stress island design theory of hollow slab floors, "The First National Technical Exchange Conference on Cast-in-Place Concrete Hollow Floor Structures", Shanghai, 2005), as well as more in-depth theoretical research (Xie Jingzhong, Macroscopic basic constitutive relationship of cast-in-place hollow slabs, "China Civil Engineering Journal", 2006 Vol.39(7), P57-62), and international journals (Jing-Zhong Xie, Macroscopic Elastic Constitutive Relationship of Cast-in-Place Hollow-Core Slabs, Journal of Structural Engineering, ASCE, 2009 Vol.135(9), P1040–1047). The theory and method are implemented in the large-scale engineering software ("Jia Gou STRAT, engineering finite element and CAD software") founded by the inventor of the utility model, and have been widely used in floor slabs with large loads (such as garage roofs) and large spans (such as meeting rooms, canteens, and factories) for more than a decade. The inventor of the utility model once advocated the use of hollow slabs or ribbed slabs with narrow ribs in medium-span and small-load floor slabs (such as office buildings, hotels, and schools), which can achieve more savings in steel and concrete than traditional beam-slab floors. However, as a cast-in-place concrete structure, the installation, positioning, and anti-floating of the internal formwork are relatively cumbersome, which hinders its practical application.

[0009] Building assembly poses new requirements and also brings new opportunities. The present utility model provides a combined hollow floor slab, introducing the prefabricated idea into the hollow slab floor, not only successfully overcoming problems such as the installation, positioning, and anti-floating of the internal formwork during the cast-in-place concrete process, but also making the structure thinner and lighter by utilizing the advantages of prefabricated components, thereby further enhancing its economic advantages. On the other hand, introducing the idea of hollow slab floors into prefabrication overcomes the current problems of high material consumption and large self-weight of prefabricated structures, leading to a breakthrough in prefabrication. The inventor of the utility model introduced this technology at the "Fourth China Building Industrialization Integration Development Industry Summit" (September 2023, Jinan), attracting high attention from industry insiders. Summary of the Utility Model

[0010] Aiming at the deficiencies of the existing technology, the present utility model provides a combined hollow floor slab for medium and large-span floor slabs, realizing the exemption from formwork support (or less support), with a light self-weight and convenient hoisting, no steel bar joints, a simple and fast construction process, and especially meeting the key indicators of double savings (saving steel bars and concrete) compared with traditional cast-in-place beam-slab floors.

[0011] To achieve the above object, the present utility model adopts the following technical solutions:

[0012] A combined hollow floor slab, comprising:

[0013] A bottom plate;

[0014] Box bodies, the number of the box bodies being multiple, the multiple box bodies being arranged at intervals along the length direction of the bottom plate and fixed to the top surface of the bottom plate (1); the interval gaps between the box bodies are reserved spaces for the later-cast transverse rib beams of the floor slab; the width of the box bodies is smaller than the width of the bottom plate, and the interval gaps between two columns of the box bodies are reserved spaces for the later-cast longitudinal rib beams of the floor slab;

[0015] Connecting members, a plurality of the connecting members being fixed in the interval gaps between the box bodies arranged above the bottom plate to connect the box bodies; the width of the connecting members is smaller than the width of the box bodies to reserve the working surface of the later-cast transverse rib beams and to be used for arranging rib beam stirrups.

[0016] It can be seen from the above technical solutions that the bottom plate, the box bodies and the connecting members form a precast hollow floor slab, which bears the construction load of the floor slab and also serves as a formwork for the later-cast concrete. A plurality of precast hollow floor slabs are closely assembled transversely to cover a floor slab span. Reinforcing bars are laid in the longitudinal and transverse box intervals and then concrete is cast to form bidirectional rib beams, and distribution bars are arranged on the top surfaces of the box bodies and then concrete is cast to form a floor slab panel, and the two together form a building floor slab that meets the bearing and use functions.

[0017] Preferably, the bottom plate is a precast concrete plate or a steel plate. The length is the floor slab span, and the width is a multiple of the box body size of 1-2 m and meets the requirements of transportation and hoisting. When it is a concrete plate, a steel wire mesh is arranged in the plate to improve the strength and ductility; when it is a steel plate, reinforcing ribs are rolled on the plate surface to improve the stiffness of the bottom plate.

[0018] Preferably, when the bottom plate is a precast concrete plate, the thickness is 1 cm to 3 cm. The characteristic of the precast bottom plate is very thin. The thickness of the concrete plate is 1-3 cm, which is equivalent to the concrete cover thickness and also serves as the cover for the later-cast rib beams. ① The very thin precast bottom plate makes the effective stress height of the rib beam steel bars the same as that of the cast-in-place structure, and has the same bearing capacity as the cast-in-place structure. ② The very thin precast bottom plate makes the bottom steel bars of the longitudinal and transverse rib beams at the same height, so that the bearing capacities of the floor slab in the longitudinal and transverse directions are the same, and it becomes a fully bidirectional slab in the true sense. ③ Although the bottom plate is very thin, due to the box-shaped structure with extremely high stiffness formed by the bottom plate and the box bodies, and the supporting and restraining effect of the side plates of the box bodies on the bottom plate, the true overhanging length of the bottom plate does not exceed 10 cm, and it has great strength and toughness to meet the collisions and impacts that may occur in transportation, construction and other links.

[0019] Preferably, the box body includes a top plate, longitudinal side plates, and transverse side plates; the top plate and longitudinal side plates are steel plates or concrete plates that directly participate in the force; the transverse side plates are steel plates or concrete plates, wooden boards, or plastic plates that do not directly participate in the force and only serve as lateral strengthening and formwork for post-cast concrete; the thickness of the steel plate is 0.5 mm to 2.0 mm, and ribs are formed on the surface to enhance the out-of-plane stiffness, and the thickness of the concrete plate is 10 mm to 20 mm.

[0020] Preferably, the connecting member is a steel plate or a concrete plate; when the connecting member is a steel plate, its thickness is not less than the thickness of the steel plate of the box body, or it is a multi-layer stack or U-shaped or L-shaped bend of steel plates. Since the connecting member is only under compression and not under tension, the connection requirements between the connecting member and the box body are relatively low, and it only needs to be fixed with rivets or bolts.

[0021] Preferably, the box body is reliably connected to the bottom plate to form an integral force-bearing structure. The bottom edge of the box body is forked and bent. When the bottom plate is a concrete plate, the box body is integrally cast, riveted, or bolted to the bottom plate; when the bottom plate is a steel plate, the box body is welded, riveted, or bolted to the bottom plate.

[0022] Preferably, the combination of the bottom plate, the box body, and the connecting member forms a precast hollow component with greater stiffness, namely a composite hollow floor slab. Its strength and stiffness meet the load-bearing requirements during construction and also serve as formwork for post-cast concrete. Its characteristic is that it is used for both construction load-bearing and post-cast formwork, which is different from the general precast hollow slab where different components are used for construction load-bearing and post-cast formwork.

[0023] Preferably, for the composite hollow floor slab, its significant characteristic is that the box body participates in the force and bears the construction load, replacing the steel bar trusses, steel pipes, etc. in the general floor slab, and has greater stiffness than the latter. Since the box body also serves as the inner formwork of the hollow slab and restrains and strengthens the precast bottom plate, it has multiple functions in one and has a very high cost performance.

[0024] Preferably, the spacing distance between two adjacent box bodies is 10 cm to 20 cm, and the reserved distance between the longitudinal side plate and the side edge of the bottom plate is 1 cm to 10 cm, meeting the width requirements of the post-cast rib beam. The longitudinal and transverse gaps between the box bodies are aligned and penetrated, and the steel reinforcement cage is placed and then post-cast with concrete to form the rib beam that finally bears the load of the floor slab. Its characteristic is that it is completely equivalent to cast-in-place, without pre-buried steel bars and steel bar joints, and without the bonding surface between new and old concrete (the bottom plate is very thin and only serves as a protective layer), making the final floor slab structure safer and more reliable.

[0025] Preferably, post-cast concrete is poured on the top plate of the box body to form an intercostal panel with a thickness of 3 cm to 15 cm, which is specifically determined by the floor load and building functions. The post-cast intercostal panel serves as the flange of the rib beam and participates in the final load-bearing of the floor slab.

[0026] As can be seen from the above technical solutions, compared with the prior art, the present utility model discloses a combined hollow floor slab, which has the following beneficial effects:

[0027] (1) Achieve "double savings": Combining with the design theory and method proposed by the inventor in the early years, the present utility model uses less steel and concrete in medium and large-span floor slabs than the currently mainstream cast-in-place beam-slab floor, achieving "double savings". This is a breakthrough technical indicator, changing the current situation of more materials used in prefabrication, eliminating the huge obstacle of high prefabrication cost, enabling prefabrication to have endogenous advantages and being spontaneously applied. At the same time, due to this significant economic advantage, it can be adopted even in non-prefabricated buildings.

[0028] (2) High quality and equivalent to cast-in-place concrete: During the construction of the present utility model, the formwork support during construction is completely separated from the final load-bearing structure. The combined hollow floor slab is only used as a formwork during construction. The rib beams and the intercostal panels as the final load-bearing structures are completely cast-in-place, and the rib beam steel bars are also tied in the same way as the cast-in-place ones, without the problems of general precast and post-cast joint surfaces and embedded steel bar joints. The mechanical properties are completely equivalent to those of the cast-in-place floor slab, ensuring the reliability of the final structure.

[0029] (3) Two-way slab force: Since the bottom slab is very thin and only equivalent to the concrete cover thickness, the longitudinal and transverse bottom longitudinal bars of the rib beams can be placed on the bottom slab without restriction, and the stress heights are the same, which is a two-way slab in the complete sense. Therefore, its economy is significantly better than that of one-way stressed composite slabs, floor slabs, and steel bar truss composite slabs.

[0030] (4) Completely free of formwork support: Since the precast bottom slab is very thin, multiple precast hollow floor slabs are closely assembled horizontally without gaps, achieving completely free of formwork support and meeting the requirements of building industrialization and assembly.

[0031] (5) Free of support or less support: The combined hollow floor slab is a box-shaped load-bearing structure, and its stiffness and strength are much greater than those of steel bar trusses and steel pipe trusses. The unsupported slab span is greater than the latter. For large spans and large construction loads, the steel plate thickness can be increased to achieve no support, or a small amount of support can be set while maintaining the economic steel plate thickness (the optimal economic condition).

[0032] (6) Light self-weight: The combined hollow floor slab has a very light self-weight. For example, the weight of an 8 - 9m slab span is about 60kg / m 2 , which is much lighter than general composite slabs and floor slabs, and even lighter than some in-situ hollow slab inner molds. Its self-weight is light and it is extremely convenient for hoisting and installation.

[0033] (7) Inexpensive: Firstly, the precast floor decking is light in self-weight, so less materials are used naturally and the cost is low. Secondly, the precast hollow components are only used briefly as formwork during construction and have no durability requirements, so cheaper materials can be selected. More importantly, all the materials used in the present utility model have practical uses and there is no redundancy. For example, the box body is used as the internal form of the hollow slab, and the bottom plate is used as the protective layer of the rib beam and replaces the ceiling of the general beam-slab floor. There are no additional components such as steel pipes and steel bar trusses in the general floor decking that only have temporary uses and cannot be used for the final structural load-bearing.

[0034] (8) Good toughness and reliable quality: The composite hollow floor decking is a box-shaped stress-bearing structure. The wall panels support and restrain each other, reducing the stress-bearing length of the plate. For example, the overhanging length of the precast bottom plate is less than 10 cm. Although the plate is very thin, it still has great stiffness and toughness, and has much stronger anti-collision and impact resistance than the general steel truss composite slab, reducing losses and indirectly reducing costs.

[0035] (9) Simple to manufacture: The manufacture of the composite hollow floor decking only involves two processes: cutting and connecting thin iron sheets and pouring the bottom plate. The manufacturing process is very simple and can be batch-processed in factories, further reducing the project cost. By analogy, the manufacture of the prestressed steel pipe truss floor decking involves multiple processes such as steel bar bending, steel bar welding, prestress tensioning, bottom plate pouring, and steel pipe grouting.

[0036] (10) Convenient for construction: The composite hollow floor decking has no overhanging steel bars. After being installed in place, it will be a clean and tidy working interface, which is convenient for subsequent construction. Generally, the composite slab and floor decking have overhanging steel bars or inverted U-shaped reserved stirrups, which will increase the labor cost due to the difficulty of subsequent steel bar binding.

[0037] (11) Easy to ensure construction quality: In the present utility model, the box body is fixed on the bottom plate, and its position is fixed and will not shift, and the problem of anti-floating of the internal form is completely eliminated, ensuring the construction quality from the source. For the in-situ cast hollow slab internal form, on-site positioning and special tie rods for anti-floating are required. Once the measures are not in place, the internal form will shift and float during concrete vibration, resulting in serious consequences such as changes in the dimensions of the rib beam and the panel between ribs and insufficient actual bearing capacity.

[0038] (12) Technical measures to avoid adverse factors: If all the rib beam steel bars of the present utility model are bound on-site, the on-site workload will increase slightly. The steel bar cage of the rib beam in one direction can be bound well in the factory or on the ground and then hoisted into place. In this way, only the one-way rib beam steel bars need to be bound on-site, and the on-site workload is equivalent to that of the general composite slab and floor decking. Because the latter also needs to bind the longitudinal and transverse top bars and the transverse bottom bars on-site. Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0040] Figure 1 Structural schematic diagram of a single precast component of the composite hollow floor slab provided by the present invention;

[0041] Figure 2 Structural schematic diagram of a floor slab with multiple composite hollow floor slabs densely and horizontally laid to cover an entire floor;

[0042] Figure 3 Detail drawing of a single box body and corresponding connecting pieces provided by the present invention;

[0043] Figure 4 For Figure 2 Cross-sectional view of the structure after binding steel bars and pouring concrete in the middle floor slab;

[0044] Figure 5 Structural schematic diagram of the integral box body of the composite hollow floor slab provided by the present invention;

[0045] Figure 6 Structural schematic diagram of the concrete box body of the composite hollow floor slab provided by the present invention;

[0046] Figure 7 Simplified calculation model diagram of the composite hollow floor slab for Scheme 1 in Embodiment 4;

[0047] Figure 8 Simplified calculation model diagram of the cast-in-place beam-slab floor for Scheme 2 in Embodiment 4;

[0048] Figure 9 Simplified calculation model diagram of the prestressed steel pipe truss composite slab for Scheme 3 in Embodiment 4.

[0049] Wherein:

[0050] 1 - Bottom plate; 2 - Box body; 21 - Stiffening rib; 22 - Top plate; 23 - Longitudinal side plate; 24 - Transverse side plate; 3 - Connecting piece; 4 - Rib beam steel bar; 5 - Transverse rib beam; 6 - Longitudinal rib beam; 7 - Intercostal panel; 8 - Whole thin steel plate; 81 - Longitudinal side plate area; 82 - Connecting piece area; 83 - End transverse plate area; 84 - Transverse side plate connection area. Detailed implementation manners

[0051] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0052] Embodiment 1:

[0053] Referring to the attached Figures 1 to 4 drawings, the embodiments of the present utility model disclose a combined hollow floor slab, including:

[0054] Bottom plate 1;

[0055] Box body 2, the number of box bodies 2 is multiple, and the multiple box bodies 2 are arranged at intervals along the length direction of the bottom plate 1 and fixed to the bottom plate 1; the interval gap between the box bodies 2 is reserved for the post-cast transverse rib beam 5 of the floor slab; the width of the box body 2 is less than the width of the bottom plate 1, and the interval gap between two columns of box bodies 2 is reserved for the post-cast longitudinal rib beam 6 of the floor slab;

[0056] Connecting piece 3, a plurality of connecting pieces 3 are fixed in the longitudinal interval gap between the box bodies 2 and are connected and fixed to the box bodies 2 to form a force-bearing structure; the width of the connecting piece 3 is less than the width of the box body 2 to reserve a working surface for the post-cast transverse rib beam 5 and arrange rib beam stirrups.

[0057] In some other specific embodiments, the bottom plate 1 is a precast concrete plate or a steel plate. When the bottom plate adopts a precast concrete plate, a steel wire mesh is arranged in the plate to enhance the strength and toughness of the bottom plate; when the bottom plate adopts a steel plate, reinforcing ribs are rolled on the steel plate surface to improve the bearing capacity of the steel bottom plate.

[0058] In some other specific embodiments, when the bottom plate 1 is a precast concrete plate, its thickness is 1 cm to 3 cm. Since the bottom plate, the box body and the connecting piece form a box-shaped force-bearing structure, and the side plate of the box body has a supporting and restraining effect on the bottom plate, the actual overhanging length of the bottom plate is very small, and it has extremely high strength and toughness. Therefore, the bottom plate can be very thin. The thickness of the thin plate is equivalent to the thickness of the concrete protective layer, so that the bottom bars of the post-cast transverse and longitudinal rib beams can be directly placed on the bottom plate, and the stress heights of the longitudinal and transverse steel bars are the same, becoming a fully two-way stress plate in the true sense, overcoming the adverse factors of the one-way stress of general precast composite slabs and further improving the economic advantages of the present utility model.

[0059] Advantageously, the top plate 22 and the longitudinal side plates 23 of the box body 2 are made of steel plates with a thickness of 0.5 mm to 2.0 mm, and are involved in the load-bearing during construction. Since the transverse side plates 23 of the box body 2 are not involved in the load-bearing during construction, they can be thinner steel plates, or concrete plates, wooden boards, or plastic plates to further reduce the construction cost. The box body 2 also serves as a template for post-cast concrete, and is multi-purpose. Since the box body 2 only plays a role during construction and has no durability requirements, a lower-priced black iron sheet can be selected.

[0060] In order to further optimize the above technical solution, the top plates and side plates of the multiple box bodies 2 are provided with stiffening ribs 21 to enhance rigidity; the length direction of the stiffening ribs 21 is parallel to the length direction of the bottom plate 1 .

[0061] In order to further optimize the above technical solution, the connector 3 is a steel plate or a concrete plate; when the connector 3 is a steel plate, its thickness is not less than the thickness of the steel plate of the box body 2, or it is a multi-layer stack of steel plates or a U-shaped bend or an L-shaped bend. Since the connector is only subjected to pressure but not tension during construction, the connection requirements with the box body are very low, and only spot welding or bolting or riveting to fix the position is required, which will simplify the production of prefabricated parts and reduce costs.

[0062] In order to further optimize the above technical solution, the box body 2 is consolidated with the bottom plate 1 to form a structure that can bear loads during construction. When the bottom plate is a concrete plate, the bottom edge of the box body 2 is staggered, bifurcated, bent, and integrally cast or riveted or bolted with the bottom plate 1; when the bottom plate is a steel plate, the bottom edge of the box body 2 is welded, riveted, or bolted with the bottom plate 1. At the same time, the consolidated box body 2 serves as a formwork for post-cast concrete, fundamentally eliminating the problem of displacement and floating of the inner formwork concrete of the general hollow slab floor during vibration, and ensuring the construction quality from the source.

[0063] In order to further optimize the above technical solution, the longitudinal and transverse spacing between two adjacent boxes 2 is 10cm to 20cm, which is a reserved space for the post-cast rib beams. The steel bars are tied in the spacing space and concrete is poured to form rib beams, which are combined with the post-cast inter-rib panels on the surface of the box to form the final floor bearing structure. Since there are no reserved steel bars, steel bar joints and post-cast concrete joint surfaces in general prefabricated floors, the structure is safe and reliable.

[0064] In some other specific embodiments, the concrete thickness of the top plate 7 is 3 cm to 15 cm.

[0065] Embodiment 2:

[0066] See attached Figure 5 The utility model embodiment discloses an integral box body of a combined hollow floor deck.

[0067] The implementation scheme of the integral box body of the utility model relates to the manufacturing methods of the box body and the connecting piece. A whole thin steel plate 8 with a length equal to the floor slab span and a width equal to the sum of the box body width and twice the box body height is cut according to the length and width of the box body, the box body interval gap and the plane width of the connecting piece, and then bent at a right angle of 90 degrees. The longitudinal side plate area 81 is bent into the longitudinal side plate of the box body, and the two connecting piece areas 82 are bent towards each other into the connecting pieces in multiple layers and stacked. The end transverse plate area 83 is bent to enhance the transverse stiffness at the end, and the transverse side plate connection area 84 is bent for the enhancement of the transverse side plate of the box body and the connection point. Since the transverse side plate of the box body does not participate in the force, a single steel plate or a concrete plate, a wooden plate, a plastic plate is adopted and welded, bolted or riveted to the box body top plate and the longitudinal side plate.

[0068] The implementation scheme of the integral box body of the utility model has all the mechanical characteristics and functional characteristics of the implementation scheme in which the box body and the connecting piece are manufactured separately in Embodiment 1. Its advantages are that the connection between the box body and the connecting piece is reduced, the processing is simpler, and it is more convenient for automatic manufacturing; its disadvantage is the lack of flexibility, and it is suitable for regular rectangular floor slabs with the same box body size and arrangement. The two complement each other to meet the requirements of different-shaped floor slabs.

[0069] Embodiment 3:

[0070] See the appendix Figure 6 , and the embodiment of the utility model discloses a concrete box body scheme for a composite hollow floor slab.

[0071] In the implementation scheme of the concrete box body of the utility model, the top plate 22, the longitudinal side plate 23, and the transverse side plate 24 of the box body 2 are all concrete thin plates. The plate thickness is 10 mm to 20 mm, and a steel wire mesh is embedded to improve the strength and crack resistance. The longitudinal side plate 23 and the transverse side plate 24 of the box body are integrally cast with the concrete bottom plate 1, and then riveted or bolted to the precast box body top plate 22; it is also possible to integrally cast or precast each part of the box body 2 separately and then connect them, and then rivet or bolt them to the bottom plate 1.

[0072] In the implementation scheme of the concrete box body of the utility model, the connection 3 is also a concrete plate, and a steel mesh is embedded to enhance the toughness. Its thickness is not less than the thickness of the box body top plate, and its width is less than half of the box body width to reserve the working space for the transverse rib beam between the two connecting bodies and for passing the stirrups of the rib beam. The concrete connecting body is generally precast separately and riveted or bolted to the concrete box body.

[0073] In this scheme, the tensile stress of the concrete bottom plate is generally still less than or close to the tensile strength of the concrete, and only a steel wire mesh needs to be configured to enhance the toughness and crack resistance. The top plate and the connecting body of the concrete box body are both in compression, and the compressive stress is far less than the compressive strength of the concrete.

[0074] The advantages of the concrete box body are obvious: ① Low cost, about 1 / 3 of that of the steel box body; ② High stiffness, about 2.5 times that of the steel box body, and a larger unsupported length can be achieved. The disadvantages of the concrete box body are also prominent: ① Heavy self-weight; ② Difficult to manufacture precast components and easy to be damaged.

[0075] The concrete box body can be a beneficial supplement to the steel plate box body solution.

[0076] Example 4:

[0077] The economic and technical advantages of the present utility model are reflected through engineering applications. Take a common frame structure in the project, with a column span of 9m in both longitudinal and transverse directions, a designed dead load of 1.0 kN / m 2 , and a live load of 5.0 kN / m 2 . The cross-section of the main beam (frame beam) between columns is 0.3m x 0.9m. For the floor slab with a length and width of 9m between the main beams, three solutions of the combined hollow floor formwork of the present utility model, the traditional cast-in-place beam-slab floor, and the prestressed concrete truss composite slab are respectively adopted, and the steel bar and concrete consumption are counted and the cost is estimated.

[0078] Solution 1:

[0079] See the appendix Figure 7 , adopt the combined hollow floor formwork of the present utility model, the total thickness of the floor slab is 0.4m, and no secondary beam is set. The length and width of the box body are about 1.0m (the actual spacing is slightly adjusted), the height is 0.33m, and the interval gap of the box body is 0.13m. The corresponding cross-section of the post-cast rib beam is 0.13m x 0.4m, the rib beam spacing is 1.13m, and the thickness of the panel between the post-cast ribs is 0.05m. According to the construction load, the thickness of the iron sheet on the top plate of the box body is 0.7mm, the thickness of the longitudinal side plate of the box body is 0.5mm, the transverse side plate of the box body is a 10mm thick wooden board, the width of the connecting piece steel plate is 300mm and the thickness is 2.0mm, and the bottom plate is a 20mm thick precast concrete plate. After checking, under the condition of the concrete pouring weight and the superimposed construction live load of 70 kg / m 2 , the precast components meet the bearing requirements of transportation, installation and post-cast concrete, etc. Among them, the tensile stress of the bottom plate is less than the tensile strength of the concrete, and only wire mesh needs to be configured to enhance the toughness and crack resistance; except for local stress concentration, the upper box body and the connecting piece are all less than the steel strength. And the deflection during construction is less than 1 / 310, and full support is completely avoided.

[0080] Solution 2:

[0081] See the appendix Figure 8 , adopt the traditional cast-in-place beam-slab floor. Two secondary beams with a cross-section of 0.25m x 0.65m are arranged longitudinally and transversely within one column span, and the thickness of the cast-in-place floor slab is 0.12m.

[0082] Solution 3:

[0083] See the appendix Figure 9, the prestressed steel pipe truss composite slab (refer to the utility model patent CN 205653944 U) is adopted. According to the slab span and design load, type GDB9010-9 in the corresponding standard atlas "Prestressed Concrete Steel Pipe Truss Composite Slab L22ZG401" of this patented technology is selected. Among them, the thickness of the precast bottom slab is 40mm, the thickness of the post-cast surface layer is 210mm, and the total thickness of the floor slab is 250mm. Designed as a one-way slab, unidirectional support negative reinforcement parallel to the bottom prestress is arranged on the top surface of the post-cast surface layer, and the specific value is determined by calculation. In the calculation model, the large slab is provided with longitudinal joints at the side beams and the middle part to correctly reflect the stress characteristics of the one-way slab.

[0084] The JG-STRAT software is used for calculation, design and drawing of construction drawings.

[0085] Three schemes are calculated as follows:

[0086] 1) Comparison of steel and concrete quantities

[0087] The actual concrete consumption (equivalent thickness) of each floor slab is counted, and the actual steel consumption of the construction drawings of slabs, beams and columns is counted (the steel quantity of columns and main beams needs to be included because it will have a significant impact on different floor slabs and is a factor that must be considered), and listed in Table 1.

[0088] For Scheme 3, the steel consumption adopts the prestressed steel wire, transverse distribution steel bars, steel pipes (2 pieces per 1m width) of type GDB9010-9 in the standard atlas "Prestressed Concrete Steel Pipe Truss Composite Slab L22ZG401", and the truss steel bars supporting the steel pipes are ignored. It includes the unidirectional support negative reinforcement in the post-cast surface layer, while the transverse distribution steel bars and other structural steel bars are ignored. For details, see Note [2] in Table 1.

[0089] It can be seen from the table that the technology of the present utility model has achieved double savings in the use of steel and concrete. (If the steel quantity includes the box body steel plate, savings can still be achieved).

[0090] 2) Cost comparison

[0091] According to the current general market price, that is, steel is 4000 yuan / ton and concrete is 500 yuan / m 3 , the direct cost of the consumption of these two main materials is estimated and listed in Table 1.

[0092] In addition to the two main materials of steel and concrete, other main factors affecting the cost need to be included.

[0093] The combined hollow floor formwork adopted in Scheme 1 has a box body and connecting piece steel plate of 7.2911 kg / m 2 , and the bottom slab concrete is 0.02 m 3 / m 2 , and the material cost is 39.1647 yuan / m 2 . The production cost is calculated at 50% and is 19.5824 yuan / m2 Then the price of the prefabricated component is 58.7471 yuan / m 2 .

[0094] For Plan 2, on-site support formwork is required, and the price is taken as 65 yuan / m according to the current market average price 2 . Here, the indirect costs caused by more in-situ labor and longer construction period are ignored

[0095] For Plan 3, the price is objectively estimated according to the consumption of basic materials such as steel bars and concrete, rather than adopting the market price of the composite slab. The prefabricated component manufacturing cost is underestimated by 30 yuan / m 2 , and the steel bar truss and non-load-bearing distribution steel bars are ignored

[0096] Considering the above main factors affecting the cost, it can be seen that the composite hollow slab floor slab of the present utility model saves 83.82 yuan / m respectively compared with the cast-in-place primary and secondary beam floor slab and the prestressed truss composite slab 2 , and saves 86.61 yuan / m compared with the prestressed truss composite slab 2 , and the saving rate reaches 30%, historically achieving cost savings for prefabricated assembled floor slabs

[0097] 3) Analysis

[0098] ① If the steel plate of the composite hollow floor slab is included in the steel bars, that is, 19.327 + 7.291 = 26.618 kg / m 2 , it is still lower than the steel bar quantity of Plan 2, which is 28.995 kg / m 2 . At the same time, the concrete quantity of 0.1305 + 0.020 = 0.1505 is also less than 0.2083 of Plan 2. The "double savings" of materials used in the present utility model is comprehensive

[0099] ② The above cost comparison for the composite hollow floor slab is a very conservative statistic. As mentioned above, the labor cost and construction period extension of Plan 1 and the construction details of the prefabricated components of Plan 2 are ignored. Also, a more important factor is not included, that is, the increase in the self-weight of the floor slabs of Plan 2 and 3, which leads to an increase in the cross-sectional area of the vertical load-bearing members of columns and walls and the foundation, as well as an increase in the cross-sectional area and steel content of the lateral force-resistant members of the seismic structure (the seismic force is approximately proportional to the self-weight)

[0100] ③ For larger spans or larger loads, the advantages of the composite hollow floor slab of the present utility model will be greater. Because when increasing the floor slab thickness for larger spans and larger loads, only the height of the rib beams increases, and the width of the rib beams and the thickness of the panel do not need to increase or only increase slightly, so there will be a higher hollowness ratio and the economic efficiency will be further improved

[0101] Table 1. Quantities and costs of each floor slab plan

[0102]

[0103] [Note 1] For Plan 1, if the steel quantity includes the box body steel plate, its value is 19.327 + 7.291 = 26.618 kg / m 2 .

[0104] [Note 2] Quantity statistics of the prestressed truss composite slab for Plan 3. According to the standard atlas "Prestressed Concrete Steel Pipe Truss Composite Slab

[0105] L22ZG401", type GDB9010-9, statistics are made based on a 1m-wide slab.

[0106] 1) 22 precast steel wires, φ H 7.0, Ap = 38.48451 * 22 = 846.65922 mm 2 , totaling 6.64627 kg / m 2 .

[0107] 2) 27 precast steel bars, φ5.0, As = 19.63495 * 27 / 9 = 58.90485 mm 2 , totaling 0.4624 kg / m 2 .

[0108] 3) 2 precast steel pipes, φ28, Ae = 87.96459 * 2 = 175.92919 mm 2 , totaling 1.38104 kg / m 2 .

[0109] 4) The top reinforcement of the post-cast support, φ16@100, length 4.7m, As = 201.0619 * 10 = 2010.619 mm 2 , totaling 8.24234 kg / m 2 .

[0110] 5) Reinforcement for the cast-in-place column and main beam, totaling 14.83539 kg / m 2 .

[0111] Total consumption of steel wires / steel bars / steel pipes: 31.56744 kg / m 2 .

[0112] Total price of steel wires / steel bars / steel pipes: 132.9160 yuan / m 2 . (Steel bars / steel pipes are 4000 yuan / ton, prestressed steel wires are 5000 yuan / ton).

[0113] Example 5:

[0114] On the basis of Embodiment 4 of the present utility model, Scheme 3 is changed from a solid composite slab to a precast hollow composite slab, that is, the mode of a closely assembled hollow composite slab (Publication No. CN 112144724 A of the utility model patent application) and a steel pipe truss prestressed concrete composite slab (Authorized Publication No. CN113089920B) is used as Scheme 4:

[0115] The total thickness of the floor slab in Scheme 4 is 0.4 m, and cavities formed by internal molds with a length and width of 1 m each are provided. The width of the rib beam is 0.2 m and the spacing is 1.2 m. The post-cast surface layer forms an upper panel with a thickness of 0.05 m between the ribs, and the precast bottom slab forms a lower panel with a thickness of 0.05 m between the ribs. The rib beam and the panel form an I-shaped stress-bearing section. Since it is a long precast bottom slab and the prestressing tendons are arranged unidirectionally, the large slab in this scheme is unidirectionally stressed. In the calculation model, longitudinal joints are provided at the side beams and the middle part of the large slab to disconnect (the calculation sketch is the same as that of Scheme 3, see Appendix Figure 9 ).

[0116] Table 2. Comparison of precast hollow floor slab schemes

[0117]

[0118] Results:

[0119] The equivalent slab thickness and the calculated reinforcement values are listed in Table 2. It can be seen that the equivalent thickness of the floor slab in Scheme 4 is nearly 50% larger, that is, the concrete consumption is 1.5 times that of Scheme 1 of the present utility model. At the same time, due to unidirectional stress, the reinforcement values at each part are significantly increased, which is 1.6 - 2.7 times that of Scheme 1 of the present utility model. It can be seen that Scheme 1 has significant economic advantages.

[0120] Analysis:

[0121] Although this embodiment is a theoretical analysis, it provides a side example to reflect the key points of the technology of the present utility model:

[0122] ① In Scheme 4, since the precast bottom slab is equipped with reinforcement and participates in the final stress, it cannot be too thin, thus forming the lower panel between the ribs of the final floor slab, that is, there are both upper panels and lower panels between the ribs. The extra lower panel between the ribs reduces the hollowness ratio, increases the concrete consumption, increases the structural self-weight, and reduces the economy.

[0123] ② In Scheme 4, the stress bottom reinforcement is in the precast slab, and it can only be unidirectionally stressed, which greatly reduces the economy of the floor slab. Although theoretically transverse reinforcement can be arranged on the top surface of the precast slab, it is still unidirectionally stressed. In Scheme 1, the bottom slab is very thin, and the bidirectional stress bars are both above the precast bottom slab and have the same stress height, which is a complete bidirectional stress in the true sense.

[0124] ③In Solution 4, the post-cast rib beam needs to accommodate the steel bar truss and cannot be too narrow. When using the precast part of the rib beam (excluding the post-cast surface layer) to replace the steel bar truss, due to construction load-bearing or internal formwork layout requirements, the rib beam also cannot be too narrow. A wider rib beam results in a low hollowness ratio and an increase in concrete consumption. In contrast, Solution 1 has no such limitations and can determine the optimal rib beam width only according to the force requirements, improving the hollowness ratio, reducing the concrete consumption, and making the structure more efficient.

[0125] In this specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For related parts, reference can be made to the description in the method section.

[0126] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composite hollow floor slab, characterized in that, Comprising: Bottom plate (1); Box bodies (2), the number of the box bodies (2) being multiple, the multiple box bodies (2) being arranged at intervals along the length direction of the bottom plate (1) and fixed to the top surface of the bottom plate (1); the interval gap between the box bodies (2) is a reserved space for the post-cast transverse rib beam (5) of the floor slab; the width of the box body (2) is less than the width of the bottom plate (1), and the interval gap between two columns of the box bodies (2) is a reserved space for the post-cast longitudinal rib beam (6) of the floor slab; Connectors (3), multiple connectors (3) being fixed in the interval gap between the box bodies (2) arranged above the bottom plate (1) to connect the box bodies (2); the width of the connector (3) is less than the width of the box body (2) to reserve a working surface for the post-cast transverse rib beam (5).

2. The composite hollow floor slab according to claim 1, wherein The bottom plate (1) is a precast concrete plate or a steel plate.

3. The composite hollow floor slab according to claim 2, wherein When the bottom plate (1) is a precast concrete plate, its thickness is 1 cm to 3 cm.

4. A composite hollow floor slab according to claim 1, characterized in that, The box body (2) includes a top plate (22), longitudinal side plates (23) and transverse side plates (24); the top plate (22) and the longitudinal side plates (23) are steel plates or concrete plates; the transverse side plates (24) are steel plates or concrete plates, wooden plates, plastic plates; the thickness of the steel plate is 0.5 mm to 2.0 mm, and the thickness of the concrete plate is 10 mm to 20 mm.

5. A composite hollow floor slab according to claim 1, wherein, The connector (3) is a steel plate or a concrete plate; when the connector (3) is a steel plate, its thickness is not less than the thickness of the steel plate of the box body (2), or it is multiple layers of steel plates stacked or U-shaped bent, L-shaped bent.

6. The composite hollow floor slab according to claim 4, wherein, The interval distance between two adjacent box bodies (2) is 10 cm to 20 cm; the reserved distance between the longitudinal side plate (23) and the side edge of the bottom plate (1) is 1 cm to 10 cm.

7. A composite hollow floor slab according to claim 2, characterized in that, The bottom edge of the box body (2) is bifurcated and bent, and is integrally cast or welded, riveted, bolted with the bottom plate (1) made of concrete, or welded, riveted or bolted with the bottom plate (1) made of steel plate.

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