Prefabricated floor slab and construction method thereof

Abstract

The application discloses a prefabricated floor slab and a construction method thereof, and relates to the technical field of fabricated building, which comprises a prefabricated slab and a steel bar truss arranged at the end of the prefabricated slab, the steel bar truss is arranged on the prefabricated slab at intervals, the steel bar truss comprises upper chord steel bars, lower chord steel bars and web bars arranged between the upper chord steel bars and the lower chord steel bars, the upper chord steel bars and the lower chord steel bars extend towards the middle area of the prefabricated slab and serve as longitudinal stress steel bars of the prefabricated slab, the end of the prefabricated slab is provided with a thinning area, so that part of the upper chord steel bars and part of the web bars are exposed from the prefabricated slab, and the thinning area forms a post-cast strip, which effectively overcomes the industry pain points of traditional prefabricated slab, such as complicated reinforcement, low binding efficiency and high labor cost, while having the advantages of convenient construction, effectively solves the problems of the traditional steel bar truss composite slab, such as difficult pipeline passing in the middle and poor rigidity in the construction stage.

Description

Technical Field

[0001] This invention relates to the field of prefabricated building technology, specifically to a prefabricated floor slab and its construction method. Background Technology

[0002] Existing prefabricated buildings primarily use two types of floor slabs: precast slabs and composite slabs. Precast slabs are manufactured in a factory and directly installed on site. They mainly include prestressed hollow core slabs (SP slabs), prestressed double-T slabs, and solid flat slabs. Their advantages include fast construction speed and reduced formwork, but their overall integrity is inferior to cast-in-place slabs. Composite slabs consist of a precast base slab and a post-cast concrete composite layer. Currently, the composite slab types used in my country are mainly precast composite slabs with steel trusses and prestressed composite slabs (prestressed concrete flat composite slabs, prestressed ribbed concrete composite slabs, prestressed concrete steel pipe truss composite slabs, prestressed hollow core composite slabs, etc.). Among these, the production process of prestressed composite slabs is relatively complex, requiring high standards for tensioning equipment and concrete strength control. Furthermore, reliable anchorage structures are needed at the ends of the slab, making joint treatment difficult. In addition, prestressing tendons are usually arranged along the length of the slab, which can cause them to cross and conflict with mechanical and electrical pipelines in the middle area of ​​the floor slab. Reserved holes or slots can weaken the effective prestress and affect the structural stress performance.

[0003] Reinforced truss composite slabs are the most widely used type of prefabricated building due to their mature production process and high degree of standardization. In these slabs, the steel trusses are permanently embedded in the concrete after the composite slab is formed. However, during the floor slab's service life, the steel trusses contribute very little to the structural load-bearing capacity. Their main function is to enhance the bending resistance of the precast base slab during construction, facilitate hoisting, and strengthen the interlocking between the precast and cast-in-place layers. The continuous steel truss installation along the entire length of the floor slab results in a large amount of steel consumption. The densely packed truss web members in the mid-span area pose a significant challenge. When pipelines and other pre-installed sleeves need to be laid in the middle of the floor slab, interference and collision with the steel trusses are highly likely, restricting pipeline placement. To avoid pipelines or to create openings, construction sites often need to cut or sever truss web members and even chord members. This arbitrary construction operation not only damages the overall load-bearing performance of the steel truss but may also weaken the load-bearing capacity of the precast base slab during construction, creating safety hazards. Meanwhile, the precast base plate of the steel truss precast composite slab has limited rigidity and bearing capacity during the construction stage. When the slab span is large, a large number of temporary supports need to be added, which increases the cost of construction measures and the construction period.

[0004] Therefore, in order to overcome the shortcomings of the existing technology, it is urgent to develop a precast floor slab and its construction method, which can effectively solve the problems of difficult pipeline passage in the middle and poor stiffness during the construction stage of traditional steel truss composite slabs while having the advantages of convenient construction. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a precast floor slab and its construction method, which, while offering the advantage of convenient construction, effectively solves the problems of difficulty in pipeline passage in the middle and poor stiffness during the construction stage in traditional steel truss composite slabs.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A precast floor slab includes a precast slab and steel trusses disposed at the ends of the precast slab. The steel trusses are spaced apart on the precast slab. Each steel truss includes top chord reinforcement, bottom chord reinforcement, and web members disposed between the top chord reinforcement and the bottom chord reinforcement. The top chord reinforcement and the bottom chord reinforcement extend toward the central region of the precast slab and serve as longitudinal reinforcing bars of the precast slab. A thinning zone is provided at the ends of the precast slab to expose part of the top chord reinforcement and part of the web members. The thinning zone forms a post-cast strip.

[0008] Preferably, the precast slab is provided with transverse reinforcing bars, which are arranged at intervals along both the thickness and length directions of the precast slab, and are perpendicular to the longitudinal reinforcing bars.

[0009] Preferably, a wiring hole is provided in the middle region of the precast slab, and the wiring hole extends toward the length or width direction of the precast slab.

[0010] Preferably, the spacing between adjacent wiring holes is 200 mm to 300 mm.

[0011] Preferably, the wiring holes are disposed between adjacent transverse reinforcing bars along the thickness direction of the precast slab.

[0012] Preferably, a reserved pipe is provided above or below the wiring hole.

[0013] Preferably, the thickness of the thinning zone is 30 mm to 60 mm.

[0014] Preferably, the precast slab is a rectangular structure, and the steel truss is provided on all four sides of the rectangular structure.

[0015] Preferably, the steel truss is evenly distributed on the precast slab.

[0016] This invention also discloses a construction method for precast floor slabs, comprising the following steps:

[0017] Precast floor slabs are manufactured in the factory;

[0018] The precast floor slabs are hoisted and installed.

[0019] Pipelines are run through precast floor slabs;

[0020] Concrete is poured into the post-cast strip.

[0021] The present invention achieves the following technical effects compared to the prior art:

[0022] By setting steel trusses at the ends of precast slabs, the traditional practice of full-length trusses is abandoned. A differentiated zoning reinforcement scheme with trusses at the ends and no trusses in the middle of the span is pioneered. It strictly follows the stress characteristics of the floor slab, and concentrates the reinforcement of the upper and lower chords in the critical stress area at the ends. This not only ensures the bending and shear resistance safety during construction and in use, but also simplifies the structure in the non-critical area in the middle of the span to achieve material optimization. At the same time, the upper and lower chords are used as the longitudinal reinforcement of the precast slab, which completely eliminates the process of separately configuring the longitudinal reinforcement of the slab. This significantly reduces the types and total amount of steel bars used, and simplifies the reinforcement structure and factory binding process from the source. It effectively overcomes the industry pain points of traditional precast slab reinforcement, such as complicated reinforcement, low binding efficiency and high labor costs. While having the advantage of convenient construction, it also effectively solves the problems of difficult pipeline passage in the middle and poor stiffness during construction of traditional steel truss composite slabs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Appendix Figure 1 This is a schematic diagram of the overall structure of the precast floor slab disclosed in this invention when no pre-reserved pipes are installed;

[0025] Appendix Figure 2 This is a schematic diagram of the overall structure when pre-reserved pipes are installed in the precast floor slab disclosed in this invention;

[0026] Appendix Figure 3 For the appendix Figure 1 A schematic diagram of the cross-sectional structure of aa;

[0027] Appendix Figure 4 For the appendix Figure 1 A schematic diagram of the cross-sectional structure of bb;

[0028] Appendix Figure 5 For the appendix Figure 2 a ， -a ， A sectional view of the structure;

[0029] Appendix Figure 6 For the appendix Figure 2 b ， -b， A sectional view of the structure;

[0030] Appendix Figure 7 This is a schematic diagram of the top view structure of the precast floor slab disclosed in this invention;

[0031] Appendix Figure 8 This is a three-dimensional structural schematic diagram of the precast floor slab disclosed in this invention;

[0032] Among them, 1. top chord reinforcement; 2. transverse reinforcing bars; 3. bottom chord reinforcement; 4. web members; 5. wiring holes; 6. precast slab; 7. post-cast strip; 8. thinning zone; 9. reserved pipes; 10. steel truss. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The purpose of this invention is to provide a precast floor slab and its construction method, which can significantly reduce the difficulty of on-site installation and connection, improve the connection fault tolerance rate, and achieve inspectable and controllable connection quality while ensuring structural safety and seismic performance, thereby effectively overcoming the defects of the prior art.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] refer to Figures 1-8The precast floor slab disclosed in this embodiment of the invention includes at least a precast slab 6 and a steel truss 10 disposed at the end of the precast slab 6. The precast slab 6 is a concrete slab. The steel truss 10 is disposed at intervals along the length and width of the precast slab 6. The steel truss 10 includes an upper chord steel bar 1, a lower chord steel bar 3, and a web member 4 disposed between the upper chord steel bar 1 and the lower chord steel bar 3. The steel truss 10 is formed by welding or binding the upper chord steel bar 1, the lower chord steel bar 3, and the diagonal web member 4. The upper chord steel bar 1 and the lower chord steel bar 3 extend toward the middle region of the precast slab 6 so that the upper chord steel bar 1 and the lower chord steel bar 3 penetrate the entire precast slab 6 and also serve as the longitudinal reinforcing bars of the precast slab 6. A thinning zone 8 is provided at the end of the precast slab 6 so that part of the upper chord steel bar 1 and part of the web member 4 are exposed in the precast slab 6. The thinning zone 8 forms a post-cast strip 7. By providing a steel truss 1 at the end of the precast slab 6, The design abandons the traditional practice of using full-length trusses and pioneers a differentiated zoning reinforcement scheme with trusses at the ends and no trusses in the middle of the span. It strictly follows the stress characteristics of the floor slab and concentrates the reinforcement of the upper and lower chords 3 in the critical stress area at the ends. This not only ensures the bending and shear resistance safety during construction and use, but also simplifies the structure in the non-critical area in the middle of the span to achieve material optimization. At the same time, the upper chord 1 and lower chord 3 are used as the longitudinal reinforcement of the precast slab 6, completely eliminating the process of separately configuring the longitudinal reinforcement of the slab. This significantly reduces the types and total amount of reinforcement, simplifies the reinforcement structure and factory binding process from the source, and effectively overcomes the industry pain points of traditional precast slab reinforcement, such as complicated reinforcement, low binding efficiency, and high labor costs. While having the advantage of convenient construction, it effectively solves the problems of difficult pipeline passage in the middle of the traditional steel truss composite slab and poor stiffness during the construction stage.

[0037] It should be noted that the diameter of the upper chord steel bar 1 and the lower chord steel bar 3 is not less than 8 mm, the diameter of the web member 4 is not less than 4.5 mm, one end of the steel truss 10 is embedded in the precast slab 6, and the upper chord steel bar 1 and the web member 4 at the other end are exposed above the end precast slab 6. The length of the steel truss 10 embedded in the end of the precast slab 6 should not be less than 100 mm.

[0038] As one implementation method, transverse reinforcing bars 2 are provided inside the precast slab 6. The transverse reinforcing bars 2 are arranged at intervals along both the thickness and length directions of the precast slab 6, that is, transverse reinforcing bars 2 are provided at both the top and bottom of the precast slab 6, forming a double-layer reinforcement. They are arranged at intervals along the length direction. The transverse reinforcing bars 2 are set perpendicular to the longitudinal reinforcing bars. By arranging the transverse reinforcing bars 2 at intervals along the thickness and length directions of the slab and perpendicular to the upper chord reinforcing bars 1 and the lower chord reinforcing bars 3, which also serve as longitudinal reinforcing bars, a two-way reinforcing bar mesh is formed, which significantly improves the overall stiffness and crack resistance of the precast slab 6 both inside and outside the plane.

[0039] As one implementation method, wiring holes 5 are provided in the middle area of ​​the precast slab 6. The wiring holes 5 extend in the length or width direction of the precast slab 6. Wiring holes 5 are provided in the non-critical stress areas of the precast slab 6, which are connected in the length or width direction. This allows the channels for power and low voltage pipelines, water pipes and other equipment to be centrally and horizontally installed inside the precast slab 6. The multi-hole layout can flexibly distinguish different pipeline functional zones and avoid pipeline interference. This design makes full use of the space conditions in the middle area where there are no truss obstructions. The pipelines run straight along the holes and completely avoid the stressed steel bars. This completely eliminates the risk of damage to the steel bars caused by on-site impact drilling. In addition, multiple pre-embedded holes can be formed in the factory mold at one time without the need for secondary processing on site.

[0040] It should be noted that prefabricated pipes can also be installed in wiring holes 5. Prefabricated pipes (such as PVC, metal or composite material pipes) are pre-embedded in wiring holes 5. The prefabricated pipes are positioned and fixed before the concrete is poured in the factory, and are formed with the slab in one piece. The pipes are seamlessly wrapped with the concrete, avoiding the impact damage to the hole wall when the pipes are installed on site and the potential leakage in later use. The inner wall of the prefabricated pipes is smooth, which greatly reduces the frictional resistance of the wires, making it convenient for the pipelines to pass through and for future replacement and upgrades.

[0041] As one implementation method, the spacing between adjacent wiring holes 5 is 200 mm to 300 mm, which not only meets the standard spacing requirements of professional pipeline joints such as building electrical and water supply and drainage, but also provides ample operating space for construction personnel, facilitating wire pulling, joint binding and subsequent inspection and maintenance.

[0042] As a preferred approach, a reserved pipe 9 is provided above or below the wiring hole 5. Another reserved pipe 9 is provided above or below the wiring hole 5 to form a layered or segmented pipeline channel system of the main wiring hole 5 and the auxiliary reserved pipe 9. The wiring hole 5 can be used for horizontal passage of high-voltage cables or main water supply pipes, while the reserved pipe 9 can provide independent channels for low-voltage cables, fire sprinkler branch pipes or gas pipelines, etc., to achieve separation of high and low voltage, and separation of water and electricity, effectively avoiding signal interference and safety hazards. At the same time, the multi-channel layout of staggered vertical or parallel horizontal arrangement allows multiple system pipelines to be installed in parallel within the same precast slab 6 without crossing or interfering, greatly improving space utilization and pipeline organization flexibility.

[0043] In one implementation, the thickness of the thinning zone 8 is 30 mm to 60 mm. The end thinning zone 8 ensures the effective connection between the steel truss 10 and the post-cast strip 7 through precise thickness control, providing a solid nodal force transmission foundation for the overall structure.

[0044] As one implementation method, the precast slab 6 is a rectangular structure with steel trusses 10 on all four sides, making the precast slab 6 a true four-sided load-bearing member. Regardless of whether the load is transmitted along the length or width, it can obtain uniform and reliable shear and bending reinforcement at the slab edge, which greatly improves the crack resistance of the slab edge during hoisting, stacking and transportation in the construction stage. It also perfectly corresponds to the rectangular structure formed by four precast wall panels, ensuring that the four sides of the floor slab can form a solid post-cast connection node with the top of the corresponding wall panel, realizing rigid force transmission in the whole circumference, and making the overall structure and seismic performance more balanced.

[0045] As an implementation method, the steel truss 10 is evenly distributed on the precast slab 6, ensuring that the spacing between each truss is consistent. This distributes the longitudinal reinforcing bars, which also serve as the upper chord steel bars 1 and the lower chord steel bars 3, in an evenly spaced grid pattern across the entire slab surface. Together with the transverse reinforcing bars 2, they form a regular and uniform two-way load-bearing skeleton, significantly improving the overall stiffness and crack resistance uniformity of the precast slab 6 under in-plane and out-of-plane loads. This avoids local weakness or stress concentration caused by uneven truss density. During the construction, hoisting, transportation, and stacking stages, the evenly distributed trusses make the load-bearing capacity of each area of ​​the slab surface more consistent, effectively preventing cracking or deformation of the slab surface caused by differences in support reaction forces. This significantly enhances the damage resistance and finished product qualification rate of the precast components.

[0046] This invention also discloses a construction method for precast floor slabs, comprising the following steps:

[0047] Step 1: Factory prefabrication preparation and steel frame forming

[0048] On the precast platform in the factory, the transverse reinforcing bars 2 are tied according to the design drawings. The transverse reinforcing bars 2 are arranged at designed intervals along the thickness (layers) and length of the precast slab 6. At the same time, steel trusses 10 are evenly arranged on the four sides of the rectangular precast slab 6, so that the upper chord reinforcing bars 1 and the lower chord reinforcing bars 3 of the trusses also serve as the longitudinal reinforcing bars at the top and bottom of the slab, forming a complete two-way steel mesh perpendicular to the transverse reinforcing bars 2. In non-critical stress areas of the slab, according to the standard of 200mm~300mm... The spacing is positioned and the core mold for the hole is installed (or PVC / metal prefabricated pipes are pre-embedded). According to the pipeline integrated design, the core mold for the reserved pipe 9 is additionally fixed above or below the wiring hole 5 to form a three-dimensional layered pipeline channel. A thinning zone 8 forming strip with a thickness of 30mm~60mm is set around the end of the slab to expose the upper chord steel bar 1 and part of the web bar 4 in this area. Then, concrete is poured, vibrated to compact and cured to the design strength. After demolding, the prefabricated floor slab with trusses on four sides and multi-level pipe holes in the middle is obtained.

[0049] Step 2: Precast floor slab hoisting, positioning, and leveling

[0050] The prefabricated floor slabs are transported to the site and horizontally hoisted using specialized lifting equipment, so that the four ends of the prefabricated floor slabs (i.e., the thinning zone 8) are accurately placed on top of the wall panels.

[0051] Step 3: Layered installation and integration of electromechanical pipelines

[0052] After the temporary support at the bottom of the slab is in place, multiple wiring holes 5 and layered reserved pipes 9 are pre-installed in the precast slab 6. Following the principles of separating strong and weak currents and water and electricity, power cables, communication cables, water supply pipes, fire sprinkler pipes, etc., are respectively threaded into the corresponding main holes and auxiliary pipes. Adjacent wiring holes 5 are spaced at a standard interval of 200mm~300mm, providing a neat operating interface for the parallel laying of pipelines. The staggered reserved pipes 9 enable three-dimensional passage without interference between pipelines of different systems. After the wiring is completed, the pipe openings are temporarily sealed for protection.

[0053] Step 4: Construction of the connection node of the end post-pouring strip 7

[0054] Side formwork is erected at the connection area between the end of the precast floor slab and the top of the wall panel (i.e., above the thinning zone 8), and additional reinforcing bars are tied. Then, post-cast concrete of the same or higher strength grade as the precast component is poured. The post-cast concrete fully covers the exposed upper chord steel bar 1 and web member 4 of the thinning zone 8. With an optimized thickness of 30mm to 60mm, it ensures sufficient concrete cover and anchorage bond length, and facilitates the insertion of vibrator to ensure compaction. The post-cast strip 7 anchors the four-sided truss of the precast floor slab to the top of the four precast wall panels as a whole, forming a rigid connection node.

[0055] Step 5: Concrete curing and formwork removal

[0056] Cover and moisturize the post-pouring strip 7. After the specimens cured under the same conditions reach the design strength standard, remove the temporary supports and side formwork. After passing the quality inspection, the upper structure can be measured and laid out on the completed floor. Repeat the above steps to construct the upper layer of prefabricated modules.

[0057] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A precast floor slab, characterized in that, The precast slab (6) includes a precast slab (6) and a steel truss (10) disposed at the ends of the precast slab (6). The steel truss (10) is disposed at intervals on the precast slab (6). The steel truss (10) includes an upper chord steel bar (1), a lower chord steel bar (3), and a web member (4) disposed between the upper chord steel bar (1) and the lower chord steel bar (3). The upper chord steel bar (1) and the lower chord steel bar (3) extend toward the middle region of the precast slab (6) and serve as longitudinal reinforcing bars of the precast slab (6). A thinning zone (8) is provided at the ends of the precast slab (6) so that part of the upper chord steel bar (1) and part of the web member (4) are exposed on the precast slab (6). The thinning zone (8) forms a post-cast strip (7).

2. The precast floor slab according to claim 1, characterized in that, The precast slab (6) is provided with transverse reinforcing bars (2). The transverse reinforcing bars (2) are arranged at intervals along the thickness direction and the length direction of the precast slab (6). The transverse reinforcing bars (2) are arranged perpendicular to the longitudinal reinforcing bars.

3. The precast floor slab according to claim 2, characterized in that, Wiring holes (5) are provided in the middle region of the precast slab (6), and the wiring holes (5) extend toward the length or width of the precast slab (6).

4. The precast floor slab according to claim 3, characterized in that, The spacing between adjacent wiring holes (5) is 200 mm to 300 mm.

5. The precast floor slab according to claim 3, characterized in that, The wiring hole (5) is provided between adjacent transverse reinforcing bars (2) along the thickness direction of the precast slab (6).

6. The precast floor slab according to claim 3, characterized in that, A reserved pipe (9) is provided above or below the wiring hole (5).

7. The precast floor slab according to claim 1, characterized in that, The thickness of the thinning zone (8) is 30 mm to 60 mm.

8. The precast floor slab according to claim 1, characterized in that, The precast slab (6) is a rectangular structure, and the steel truss (10) is provided on all four sides of the rectangular structure.

9. The precast floor slab according to claim 8, characterized in that, The steel truss (10) is evenly distributed on the precast slab (6).

10. A construction method for precast floor slabs, characterized in that, Includes the following steps: Precast floor slabs are manufactured in the factory; The precast floor slabs are hoisted and installed. Pipelines are run through precast floor slabs; Concrete is poured into the post-cast strip (7).

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