Integrated stress-free disassembly formwork steel bar truss laminated board

Abstract

The present application relates to the technical field of fabricated structure floor component, in particular to a one-piece stress-free formwork steel bar truss laminated slab, which forms a distributed concrete key by protruding in the local area of the prefabricated flat plate of the prefabricated stress bottom plate, and the distributed concrete key is arranged according to the position of the lower chord steel bar of the prefabricated stress bottom plate and the inclined web steel bar connecting node, and the lower chord steel bar of the steel bar truss and the inclined web steel bar connecting node position are reliably anchored by the distributed concrete key, so that the prefabricated flat plate and the steel bar truss form a combined section and work together in the construction stage, the bending stiffness and strength of the prefabricated flat plate are significantly improved, and the characteristics of less support or support-free within a certain span of the prefabricated flat plate in the construction process of the post-poured top laminated layer are realized; the reliable constraint of the stress node when the prefabricated flat plate and the post-poured laminated layer work together through the steel bar truss is ensured, and the local protruding distributed concrete key enhances the transverse and longitudinal shear slip resistance of the laminated interface.

Description

Technical Field

[0001] This invention relates to the field of prefabricated structural floor slab components, and in particular to an integrated load-bearing, non-removable formwork reinforced steel truss composite slab. Background Technology

[0002] Compared with traditional cast-in-place concrete structures, prefabricated concrete structures have significant advantages in terms of construction quality, speed, and cost. They are in line with my country's green, low-carbon, and sustainable development concepts and are one of the important directions for the development of building structures in my country.

[0003] Precast reinforced concrete composite slabs are one of the most widely used floor slab types for horizontal members in prefabricated concrete structures. Their method of precasting the base slab in a factory and then pouring the composite layer on-site reduces on-site wet work and improves construction efficiency. However, existing precast reinforced concrete composite slabs still exhibit certain drawbacks, mainly as follows:

[0004] The existing common reinforced concrete composite slab configuration is generally a 60mm precast base slab + 70mm post-cast layer. The large thickness of the precast base slab results in its heavy weight, which is not conducive to transportation and hoisting. On the other hand, it compresses the space of the top post-cast layer, making it more difficult to reserve and embed water and electricity pipelines in the slab. At the same time, the common reinforced concrete composite slab also exposes the problem of easy cracking at the bottom of the slab. For example, Chinese Utility Model Patent Application No. 201120451880.6 discloses a self-supporting ribbed reinforced concrete composite floor slab, which consists of a precast ribbed reinforced concrete base slab and a cast-in-place concrete composite layer. The precast ribbed reinforced concrete base slab is composed of a steel truss mesh and ribbed concrete poured on it; the steel truss mesh consists of steel trusses and additional reinforcing bars placed on the lower chord of the steel trusses and perpendicular to the steel trusses; the ribbed concrete consists of the precast concrete base slab and ribs formed at the trusses. The steel trusses are located in the middle of the longitudinal ribs, greatly increasing the flexural stiffness of the floor slab during construction, and its applicable span is larger than that of ordinary ribbed composite floor slabs. Its longitudinal ribs greatly improve the flexural stiffness of the floor slab, making it suitable for large-span unsupported systems and significantly shortening the construction process. The self-supporting ribbed reinforced concrete composite floor slab has ribbed grooves, greatly improving the overall connection performance of the floor slab. However, because its lower chord is located below the ribs of the precast concrete base slab, the base slab is relatively thick, making hoisting more difficult. In addition, because its steel truss is located in the middle of the longitudinal ribs, the cast-in-place concrete relies only on the longitudinally set web reinforcement to combine with the precast concrete base slab with the ribbed steel truss below, resulting in poor longitudinal shear resistance.

[0005] Chinese invention patent application number 201310080402.2 discloses a ribbed steel truss concrete composite slab and its construction method. The background art references the aforementioned self-supporting ribbed steel truss concrete composite slab, arguing that since the steel truss is entirely arranged within the concrete ribs, it fails to effectively utilize the advantages of the steel truss in improving stiffness, facilitating hoisting, enhancing the composite effect, and allowing pipelines to run under the top chord reinforcement. To address this issue, a new technical solution is adopted, but the bottom transverse and longitudinal reinforcement of the composite slab are arranged in a precast base slab, which is cast using ordinary concrete. Due to limitations in material properties and the protective layer required for double-layer reinforcing steel, the thickness of the precast base slab is not significantly different from that of existing ordinary composite slab precast base slabs. On this basis, the continuous arrangement of concrete ribs along the longitudinal direction of the precast base slab further exacerbates the construction difficulty of reserving space for pipelines within the slab. On the other hand, the continuously arranged concrete rib configuration can only act as shear keys in the direction perpendicular to the ribs to improve the bonding between the precast layer and the composite layer. In the parallel direction, the bonding between the concrete ribs and the composite layer still relies solely on the adhesive friction at the composite interface, failing to fully utilize the structural function of the concrete ribs and wasting materials to some extent.

[0006] For example, Chinese utility model patents with patent application numbers 202023039240.2 and 202222710535.0 disclose composite slabs that do not require dismantling of the bottom formwork. The precast bottom formwork is set at the bottom of the truss reinforcement. Although the thickness of the precast bottom formwork can be reduced, the two are only connected by a simple tie without considering the shear slip resistance of the connection interface. Therefore, in such composite slabs, the precast bottom formwork only serves as the bottom formwork of the post-cast layer. On the one hand, it cannot independently resist bending load during the construction stage and cannot meet the requirements of less support or no support. On the other hand, it basically cannot work together with the composite layer and bear the load as a whole during the use stage, resulting in a waste of the beneficial contribution of the bottom formwork material and thickness to the moment of inertia of the section, and low economic efficiency.

[0007] Furthermore, existing methods for splicing joints in conventional reinforced truss composite slabs mainly employ two approaches. First, for precast slabs with side reinforcement, since the transverse reinforcement extending from the slab edge is on the same plane as the precast slab, it cannot extend into adjacent precast slabs; therefore, splicing can only be done using post-cast strips. Second, for precast slabs without side reinforcement, a close-fitting connection method is typically used. This involves adjacent precast slabs with their sides tightly abutting and additional transverse reinforcement above the abutment, followed by the pouring of the upper composite layer to form a unified structure. The main drawbacks are: the post-cast strip connection process is cumbersome, increasing material consumption and reducing construction efficiency; and the close-fitting connection, due to the simple physical contact between adjacent precast slabs below the post-cast layer, coupled with the significant thickness of conventional precast slabs, greatly weakens the bending resistance of the weak section formed at the splice location. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies, such as the difficulty in simultaneously satisfying the requirements of reducing the thickness of the precast base plate, ensuring the rigidity of the precast base plate during the construction stage, reducing the difficulty of pipeline pre-embedding construction, and ensuring the shear resistance of the composite slab contact surface, and to provide an integrated load-bearing, formwork-free steel truss composite slab.

[0009] This invention provides an integrated load-bearing, non-removable formwork reinforced steel truss composite slab, comprising a precast load-bearing base slab and a post-cast composite layer; the precast load-bearing base slab comprises a precast flat plate, distributed concrete keys, and at least two reinforced steel trusses; The steel truss is arranged longitudinally along the precast slab, and all the steel trusses are distributed at intervals transversely along the precast slab. The steel truss includes an upper chord steel bar, a lower chord steel bar, and diagonal web steel bars connecting the two. Both the upper chord steel bar and the lower chord steel bar are arranged longitudinally along the precast slab. The precast slab has raised sections in certain areas to form distributed concrete keys; the distributed concrete keys are spaced along the transverse direction of the precast load-bearing base slab according to the arrangement of the steel truss; the distributed concrete keys are discontinuously arranged along the longitudinal direction of the precast load-bearing base slab according to the connection nodes of the lower chord steel bars and the diagonal web steel bars, and the connection nodes are anchored within the distributed concrete keys. A fiber reinforcement layer is provided inside the prefabricated slab; The post-cast composite layer includes a top steel mesh, a bottom steel mesh, and a post-cast concrete layer; the top steel mesh and the bottom steel mesh are respectively arranged at the top and bottom of the post-cast concrete layer; the post-cast concrete layer is poured onto the upper part of the precast load-bearing base slab, and the post-cast concrete layer wraps the steel truss so that the precast load-bearing base slab and the post-cast composite layer form an integral whole.

[0010] Preferably, the thickness of the precast slab is not less than 15mm and the thickness of the precast slab is not greater than 30mm.

[0011] Preferably, each of the steel trusses has two lower chord steel bars and one upper chord steel bar. The two lower chord steel bars are spaced apart and at the same height along the transverse direction of the precast load-bearing base plate, and the horizontal projection of the upper chord steel bar is located in the middle of the horizontal projection of the two lower chord steel bars.

[0012] Preferably, the distributed concrete key has a rectangular planar projection, the length of the distributed concrete key along the transverse direction of the precast load-bearing base plate is not less than the sum of the center-to-center distance of two adjacent lower chord reinforcement bars and three times the diameter of the lower chord reinforcement bars, and the width of the distributed concrete key along the longitudinal direction of the precast load-bearing base plate is not less than 50 mm.

[0013] Preferably, when the center distance between two adjacent lower chord reinforcing bars in the steel truss is greater than 100mm, the distributed concrete key is separated between the two adjacent lower chord reinforcing bars to form two sub-concrete components, and each lower chord reinforcing bar passes through a row of the sub-concrete components.

[0014] Preferably, the upper surface of the distributed concrete key is lower than the lower edge of the upper chord reinforcement, and the distance between the distributed concrete key and the upper edge of the lower chord reinforcement is not less than twice the diameter of the lower chord reinforcement.

[0015] Preferably, the top reinforcing mesh is composed of several top longitudinal reinforcing bars and top transverse reinforcing bars intersecting perpendicularly in pairs, and the top reinforcing mesh is connected to the top chord reinforcing bars through the top transverse reinforcing bars passing below the top chord reinforcing bars; The bottom reinforcing mesh is composed of several bottom longitudinal reinforcing bars and bottom transverse reinforcing bars intersecting perpendicularly in pairs. The bottom reinforcing mesh is connected to the bottom chord reinforcing bars through bottom transverse reinforcing bars passing above the bottom chord reinforcing bars.

[0016] Preferably, the bottom transverse reinforcing bars extend outward from the edge of the post-cast composite layer and into the post-cast composite layer of the adjacent composite slab.

[0017] Preferably, the fiber reinforcement layer is made of FRP mesh and is arranged at the bottom of the precast slab.

[0018] Preferably, the precast load-bearing base plate is integrally cast using ultra-high performance concrete, and the standard value of the compressive strength of the precast load-bearing base plate is not less than 100 MPa, the standard value of the elastic tensile strength of the precast load-bearing base plate is not less than 5 MPa, and the standard value of the flexural strength of the precast load-bearing base plate is not less than 12 MPa.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides an integrated, non-removable, precast steel truss composite slab. Distributed concrete keys are formed by protruding in localized areas of the precast slab of the precast load-bearing base slab. These keys are spaced along the transverse direction of the precast load-bearing base slab according to the arrangement of the steel truss. The distributed concrete keys are also discontinuously arranged along the longitudinal direction of the precast load-bearing base slab according to the connection points of the lower chord and diagonal web reinforcement, without affecting the arrangement of the top and bottom steel mesh and the reserved space for pipelines. Furthermore, the connection points of the lower chord and diagonal web reinforcement of the steel truss are anchored in the distributed concrete keys. This reliable anchorage of the steel truss through the distributed concrete keys allows the precast slab and steel truss to form a combined section and cooperate in load-bearing during the construction phase, significantly improving the bending stiffness and strength of the precast slab. This achieves the desired performance during the construction of the post-cast top composite layer. The characteristics of requiring minimal support or eliminating support within a certain span, along with the fiber reinforcement layer within the precast slab, allow for a reduction in the thickness of the precast slab. By arranging distributed concrete keys to embed the steel truss, without affecting the arrangement of the top and bottom steel mesh and the reserved pipelines, reliable constraints are ensured at the stress nodes when the precast slab and the post-cast composite layer work together to transfer loads through the steel truss. On the other hand, the locally protruding distributed concrete keys effectively bear the transverse and longitudinal shear resistance of the composite interface, further enhancing the transverse and longitudinal shear slip resistance of the interface. This enables the precast slab and the post-cast composite layer to work together and bear loads as a whole during the service stage of the composite slab, making full use of the beneficial contribution of the precast slab material and thickness to the section moment of inertia, saving materials while further improving the bending performance of the composite slab. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the prefabricated load-bearing base plate component of Embodiment 1 of the present invention; Figure 2 This is a front view of the integrated load-bearing, non-removable formwork steel truss composite slab of Embodiment 1 of the present invention; Figure 3 This is a side view of the integrated load-bearing, non-removable formwork steel truss composite slab of Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the splicing of adjacent composite plates in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the prefabricated load-bearing base plate component of Embodiment 2 of the present invention; Figure 6 This is a front view of the integrated load-bearing, non-removable formwork steel truss composite slab of Embodiment 2 of the present invention.

[0021] The markings in the diagram are as follows: 1. Precast load-bearing base slab; 11. Precast flat plate; 12. Distributed concrete key; 121. Sub-concrete component; 13. Steel truss; 131. Top chord reinforcement; 132. Bottom chord reinforcement; 133. Diagonal web reinforcement; 14. Fiber-reinforced layer; 2. Post-cast composite layer; 21. Top steel mesh; 22. Bottom steel mesh; 211. Top longitudinal reinforcement; 212. Top transverse reinforcement; 221. Bottom longitudinal reinforcement; 222. Bottom transverse reinforcement; 23. Post-cast concrete layer. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0023] Unless otherwise specified, the terms "upper," "lower," "left," "right," "center," "inner," and "outer," etc., used in the description of specific embodiments of the present invention to indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is usually placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, and for enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0024] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are arranged as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in "horizontal," "vertical," "suspended," "parallel," or "coaxial" directions, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0025] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0026] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0027] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to connection methods commonly used in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0028] Example 1 See Figures 1-4 A precast load-bearing, formwork-free reinforced truss composite slab, comprising a precast load-bearing base slab 1 and a post-cast composite layer 2; The precast load-bearing base plate 1 includes a precast flat plate 11, distributed concrete keys 12, and at least two steel trusses 13; The thickness of the precast slab 11 is smaller than that of a conventional precast base slab, less than 60mm. In this embodiment, a fiber reinforcement layer 14 is provided inside the precast slab 11. Through the reinforcement of the fiber reinforcement layer 14, the thickness of the precast slab 11 can be set to be no less than 15mm and no more than 30mm. This ensures the thickness of the reinforcing steel protective layer while avoiding excessive thickness of the precast slab 11 from affecting the reserved space for water and electricity pipelines within the composite slab. FRP (Fiber Reinforced Polymer) is a composite material formed by bonding high-performance reinforcing fibers together with a matrix material such as epoxy resin through weaving or winding. It features good durability and high strength. The fiber reinforcement layer 14 uses FRP mesh fabric, arranged at the bottom of the precast slab 11, utilizing its binding effect to improve the tensile strength and crack resistance of the precast slab 11.

[0029] The steel truss 13 is arranged longitudinally along the precast slab 11, and all the steel trusses 13 are distributed laterally at intervals along the precast slab 11. The steel truss 13 is composed of an upper chord steel bar 131, a lower chord steel bar 132, and a diagonal web steel bar 133 connecting the two. The upper chord steel bar 131 and the lower chord steel bar 132 are both arranged longitudinally along the precast slab 11. like Figures 1-3 As shown, the steel truss 13 has two lower chord steel bars 132 and one upper chord steel bar 131. The two lower chord steel bars 132 are spaced apart and at the same height along the transverse direction of the precast load-bearing base slab 1. The horizontal projection of the upper chord steel bar 131 is located in the middle of the horizontal projections of the two lower chord steel bars 132. The diagonal web steel bar 133 connects the two lower chord steel bars 132 and the upper chord steel bar 131, forming an isosceles triangle in both the longitudinal and transverse directions.

[0030] The precast slab 11 has protrusions in local areas to form distributed concrete keys 12; the distributed concrete keys 12 are spaced apart along the transverse direction of the precast load-bearing base slab 1 according to the arrangement position of the steel truss 13; the distributed concrete keys 12 are discontinuously arranged along the longitudinal direction of the precast load-bearing base slab 1 according to the connection node position of the lower chord steel bar 132 and the diagonal web steel bar 133, forming a distributed layout in the plane of the precast load-bearing base slab 1, and the connection node of the lower chord steel bar 132 and the diagonal web steel bar 133 is anchored in the distributed concrete keys 12, and the connection between the steel truss 13 and the precast load-bearing base slab 1 is realized through the distributed concrete keys 12; To improve the strength of the precast load-bearing base plate 1, reduce its thickness, and enhance its crack resistance, the precast load-bearing base plate 1 is integrally cast using ultra-high performance concrete, i.e., the distributed concrete key 12 and the precast slab 11 are integrally cast. The standard value of the compressive strength of the precast load-bearing base plate 1 is not less than 100 MPa, the standard value of the elastic tensile strength is not less than 5 MPa, and the standard value of the flexural strength is not less than 12 MPa.

[0031] To prevent anchorage failure of the lower chord reinforcement 132 and the connection node between the lower chord reinforcement 132 and the diagonal web reinforcement 133 due to insufficient concrete enclosure during the stress process, the distributed concrete key 12 has a rectangular planar projection. Its length along the transverse direction of the precast load-bearing base plate 1 is not less than the sum of the center-to-center distance of the adjacent lower chord reinforcement 132 and three times the diameter of the lower chord reinforcement 132, and its width along the longitudinal direction of the precast load-bearing base plate 1 is not less than 50mm.

[0032] To prevent the lower chord reinforcement 132 from being insufficiently confined by concrete in the height direction of the steel truss 13 and thus undergoing tensile splitting failure, and to prevent the upper surface of the distributed concrete key 12 from submerging the upper chord reinforcement 131 and affecting the composite stress performance and hoisting, the upper surface of the distributed concrete key 12 is lower than the lower edge of the upper chord reinforcement 131, and the distance between it and the upper edge of the lower chord reinforcement 132 is not less than twice the diameter of the lower chord reinforcement 132.

[0033] The post-cast composite layer 2 includes a top steel mesh 21, a bottom steel mesh 22, and a post-cast concrete layer 23; the top steel mesh 21 is arranged on top of the post-cast concrete layer 23, and the bottom steel mesh 22 is arranged at the bottom of the post-cast concrete layer 23. The top steel mesh 21 is composed of several top longitudinal reinforcing bars 211 and top transverse reinforcing bars 212 intersecting perpendicularly in pairs. In order to ensure the integrity of the steel mesh frame formed by the steel truss 13 and the top steel mesh 21, the top steel mesh 21 is connected to the steel truss 13 through the top transverse reinforcing bars 212 that pass through the bottom of the upper chord reinforcing bar 131.

[0034] The bottom steel mesh 22 is composed of several bottom longitudinal reinforcing bars 221 and bottom transverse reinforcing bars 222 intersecting perpendicularly in pairs. In order to ensure the integrity of the steel mesh frame formed by the steel truss 13 and the bottom steel mesh 22, the bottom steel mesh 22 is connected to the steel truss 13 through the bottom transverse reinforcing bars 222 that pass through the bottom chord reinforcing bars 132.

[0035] The post-cast concrete layer 23 is poured onto the upper part of the precast load-bearing base plate 1, and the post-cast concrete layer 23 wraps the steel truss 13 so that the precast load-bearing base plate 1 and the post-cast composite layer 2 form an integral whole.

[0036] See Figure 4 To ensure the splicing performance of adjacent composite slabs, the bottom transverse reinforcing steel bar 222 extends outward from the edge of the post-cast composite layer 2 and into the post-cast composite layer 2 of the adjacent composite slabs.

[0037] The integrated load-bearing, non-removable formwork reinforced truss composite slab described in this embodiment uses ultra-high performance concrete for the precast slab 11, effectively reducing the cross-sectional thickness of the precast slab 11, lightening its weight, and facilitating transportation and hoisting. Simultaneously, it significantly increases the reserved space for water and electricity pipelines in the post-cast composite layer 2, improving construction convenience. A fiber-reinforced layer 14 is provided in the precast slab 11, which, through the binding effect of the FRP mesh, improves the tensile strength and toughness of the precast slab 11, enhancing the crack resistance of the slab bottom. Considering the flexural load requirements of the precast slab 11 during the construction stage, the high strength and high toughness characteristics of ultra-high performance concrete combined with fiber-reinforced layer 14 are used to avoid the tensile failure of the bottom tension zone concrete during the flexural load of the precast slab 11 during the construction stage. The distributed concrete keys 12 reliably anchor the steel truss 13, so that the precast slab 11 and the steel truss 13 form a composite section and cooperate in bearing the load during the construction stage, which significantly improves the flexural stiffness and strength of the precast slab 11. Thus, the precast slab 11 can achieve the characteristics of low support or no support within a certain span during the construction of the post-cast top composite layer. It achieves integrated load-bearing performance of the precast slab 11. By arranging distributed concrete keys 12 to embed the steel truss 13, without affecting the bottom transverse reinforcement arrangement and pipeline reservation, it ensures reliable constraint of the load-bearing nodes when the precast slab 11 and the post-cast composite layer 2 work together to transfer loads through the steel truss 13. On the other hand, the locally protruding concrete keys effectively bear the shear resistance of the composite interface, further enhancing the interface's resistance to shear slip. Thus, it realizes the characteristics of the precast slab 11 and the post-cast composite layer 2 working together and bearing load as a whole during the service stage of the composite slab. It fully utilizes the beneficial contribution of the material and thickness of the precast slab 11 to the section moment of inertia, saving materials while further improving the bending performance of the composite slab. The bottom transverse reinforcing steel bars 222 extend outward from the edge of the post-cast composite layer 2 and into the post-cast composite layer 2 of the adjacent composite slab, thereby avoiding the construction of post-cast strips. Compared with ordinary composite slabs with close-fitting connections, the small cross-sectional thickness of the precast slab 11 greatly reduces the weakening of the component performance at the joint section. This embodiment provides a prefabricated, thin-section, crack-resistant, high-rigidity, and high-strength integrated load-bearing, non-removable formwork reinforced truss composite slab.

[0038] Example 2 See Figure 5 and Figure 6 This embodiment discloses an integrated, non-removable formwork reinforced concrete truss composite slab. The difference from Embodiment 1 is that, in this embodiment, when the center-to-center distance between adjacent lower chord reinforcement bars 132 in the reinforced concrete truss 13 is greater than 100mm, the distributed concrete key 12 is broken between the lower chord reinforcement bars 132 to form two sub-concrete components 121. Each lower chord reinforcement bar 132 passes through one row of sub-concrete components 121. This increases the contact area between the distributed concrete key 12 as a shear key at the composite interface and the post-cast composite layer 2, further improving the integrated load-bearing performance of the composite slab.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A precast load-bearing, formwork-free reinforced concrete truss composite slab, comprising a precast load-bearing base slab (1) and a post-cast composite layer (2); characterized in that, The precast load-bearing base plate (1) includes a precast flat plate (11), distributed concrete keys (12) and at least two steel trusses (13). The steel truss (13) is arranged longitudinally along the precast slab (11), and all the steel trusses (13) are distributed laterally at intervals along the precast slab (11); The steel truss (13) includes an upper chord steel bar (131), a lower chord steel bar (132), and a diagonal web steel bar (133) connecting the two. The upper chord steel bar (131) and the lower chord steel bar (132) are both arranged longitudinally along the precast slab (11). The precast slab (11) has a local area protrusion forming the distributed concrete key (12); the distributed concrete key (12) is set at intervals along the transverse direction of the precast load-bearing base plate (1) according to the arrangement position of the steel truss (13); the distributed concrete key (12) is arranged discontinuously along the longitudinal direction of the precast load-bearing base plate (1) according to the connection node position of the lower chord steel bar (132) and the diagonal web steel bar (133), and the connection node is anchored in the distributed concrete key (12); the upper surface of the distributed concrete key (12) is lower than the lower edge of the upper chord steel bar (131), and the distance between the upper edge of the distributed concrete key (12) and the lower chord steel bar (132) is not less than 2 times the diameter of the lower chord steel bar (132), so as to avoid the lower chord steel bar (132) from being insufficiently confined by concrete in the height direction of the steel truss (13) and thus undergoing tensile splitting failure, and at the same time, to avoid the upper surface of the distributed concrete key (12) from submerging the upper chord steel bar (131) and affecting the composite stress performance and hoisting; A fiber reinforcement layer (14) is provided inside the prefabricated flat plate (11). The post-cast composite layer (2) includes a top steel mesh (21), a bottom steel mesh (22), and a post-cast concrete layer (23); the top steel mesh (21) and the bottom steel mesh (22) are respectively arranged at the top and bottom of the post-cast concrete layer (23); the post-cast concrete layer (23) is cast on the upper part of the precast load-bearing base plate (1), and the post-cast concrete layer (23) wraps the steel truss (13) so that the precast load-bearing base plate (1) and the post-cast composite layer (2) form an integral whole.

2. The integrated load-bearing, non-removable formwork reinforced truss composite slab according to claim 1, characterized in that, The thickness of the precast plate (11) is not less than 15mm and the thickness of the precast plate (11) is not greater than 30mm.

3. The integrated load-bearing, non-removable formwork reinforced truss composite slab according to claim 1, characterized in that, Each of the steel trusses (13) has two lower chord steel bars (132) and one upper chord steel bar (131). The two lower chord steel bars (132) are spaced apart and at the same height along the transverse direction of the precast load-bearing base plate (1). The horizontal projection of the upper chord steel bar (131) is located in the middle of the horizontal projection of the two lower chord steel bars (132).

4. The integrated load-bearing, non-removable formwork reinforced truss composite slab according to claim 3, characterized in that, The distributed concrete key (12) has a rectangular planar projection. The length of the distributed concrete key (12) along the transverse direction of the precast load-bearing base plate (1) is not less than the sum of the center distance between two adjacent lower chord reinforcement bars (132) and three times the diameter of the lower chord reinforcement bars (132). The width of the distributed concrete key (12) along the longitudinal direction of the precast load-bearing base plate (1) is not less than 50 mm.

5. The integrated load-bearing, non-removable formwork reinforced truss composite slab according to claim 3, characterized in that, When the center distance between two adjacent lower chord steel bars (132) in the steel truss (13) is greater than 100mm, the distributed concrete key (12) separates between the two adjacent lower chord steel bars (132) to form two sub-concrete components (121), and each lower chord steel bar (132) passes through a row of the sub-concrete components (121).

6. The integrated load-bearing, non-removable formwork reinforced truss composite slab according to claim 1, characterized in that, The top steel mesh (21) is composed of several top longitudinal reinforcing bars (211) and top transverse reinforcing bars (212) intersecting each other perpendicularly. The top steel mesh (21) is connected to the top chord reinforcing bars (131) through the top transverse reinforcing bars (212) passing below the top chord reinforcing bars (131). The bottom reinforcing mesh (22) is composed of several bottom longitudinal reinforcing bars (221) and bottom transverse reinforcing bars (222) intersecting each other perpendicularly. The bottom reinforcing mesh (22) is connected to the bottom chord reinforcing bars (132) through the bottom transverse reinforcing bars (222) above the bottom chord reinforcing bars (132).

7. The integrated load-bearing, non-removable formwork reinforced truss composite slab according to claim 6, characterized in that, The bottom transverse reinforcing steel bar (222) extends outward from the edge of the post-cast composite layer (2) and extends into the post-cast composite layer (2) of the adjacent composite slab.

8. A composite slab with an integral load-bearing, non-removable formwork and reinforced concrete truss as described in any one of claims 1-7, characterized in that, The fiber reinforcement layer (14) is made of FRP mesh fabric and is arranged at the bottom of the precast slab (11).

9. A composite reinforced concrete truss slab with integrated load-bearing, non-removable formwork according to any one of claims 1-7, characterized in that, The precast load-bearing base plate (1) is integrally cast using ultra-high performance concrete. The standard value of the compressive strength of the precast load-bearing base plate (1) is not less than 100 MPa, the standard value of the elastic tensile strength of the precast load-bearing base plate (1) is not less than 5 MPa, and the standard value of the flexural strength of the precast load-bearing base plate (1) is not less than 12 MPa.

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