A hollow core slab filled with a vented box with a movable weight

Abstract

The invention relates to a hollow slab filled with air-permeable boxes and movable counterweights and a construction method thereof, belonging to the field of general building structure. The hollow slab (1) comprises slab upper iron (2), slab lower iron (3), air-permeable boxes (4), concrete (5) and movable counterweights (6). The air-permeable boxes are located between the slab upper iron and the slab lower iron, and the adjacent air-permeable boxes are solid ribs (7). The upper and lower parts of the air-permeable boxes are the upper flange (8) and the lower flange (9) of the hollow slab respectively. The air-permeable net (10) is installed at the bottom of the air-permeable boxes, and the air-permeable net has dense meshes (11). There are gaps (12) or exhaust holes (13) on the side or top of the air-permeable boxes. When the vibrating device (14) vibrates the solid ribs or the concrete of the upper flange, the movable counterweights are arranged on the upper part of the slab upper iron in the vibrating device influence area (15). The hollow slab has large span, light weight, high construction efficiency, good structural reliability, good economy and applicability.

Description

(i) TECHNICAL FIELD

[0001] The present application relates to a cast-in-situ concrete hollow floor structure, in particular to a hollow slab filled with a ventilated box with movable counterweight and its construction method, belonging to the field of general building structure. (ii) BACKGROUND

[0002] In the field of construction, with the increasing number of large-span concrete structures, more and more floors adopt hollow floor structure technology. Using lightweight filling materials to replace part of the concrete will not affect the stress performance of the structure, but can greatly reduce the self-weight of the structure. The built-in filling hollow slab contains upper and lower flanges, which have the best mechanical properties and are most widely used. According to Archimedes' law, in ordinary built-in filling hollow slab, the filling material will generate a large upward force when pouring concrete; in order to overcome the upward force, holes must be drilled in the formwork during construction, and the upward force is transmitted to the bottom of the formwork using wire ties, which is time-consuming, labor-intensive, and damaging to the formwork. In order to overcome the upward force of the filling material, in 2013, Wang Benmiao first proposed a "cast-in-situ hollow floor structure with a combined net box" (CN203514592U) and other technologies, followed by Guo Wuchang and myself who also proposed "a combined metal filling box with a blocking piece" (CN205063134U) and "a lightweight material filling box with a metal mesh surface layer" (CN105239708A) and other technologies, which promote the application of ventilated filling boxes in hollow floor structures.

[0003] However, the above-mentioned technologies have the following defects: (1) If the mesh size of the ventilated box is relatively large, the floating reduction effect is more obvious, and special anti-floating measures can not be used during construction, but the large mesh size leads to the penetration of the slurry into the ventilated box during concrete pouring, which not only increases the self-weight of the floor and reduces the bearing capacity, but also damages the concrete gradation and reduces the concrete strength, affecting the safety of the structure. (2) If the mesh size of the ventilated box is relatively small, the floating reduction effect is not obvious, and anti-floating measures are still needed during construction, although the anti-floating workload is greatly reduced compared to traditional hollow slabs, but there is still an anti-floating process of drilling holes in the formwork.

[0004] In the prior art, the floating reduction effect and the quality of concrete pouring are a pair of contradictions, under such circumstances, developing a new type of hollow slab technology with small floating force of filling material during concrete pouring, guaranteed concrete pouring quality, and simple anti-floating construction process has become an urgent problem in the industry. (iii) SUMMARY

[0005] To address the contradiction between buoyancy reduction and concrete pouring quality in existing hollow core slab technology, I conducted extensive scientific research and experiments using ordinary filling boxes and various types of permeable boxes. Based on these experiments, I reached the following original conclusions: 1. For hollow permeable boxes, as long as the bottom of the box is covered with dense and appropriately sized mesh, and the top of the box has vents to prevent pressure differences between the inside and outside of the box, buoyancy reduction can be achieved. 2. When the concrete is under vibration, the buoyancy reduction of the permeable box has an upper limit; it cannot be completely zero. In this experiment, the buoyancy was reduced by a maximum of 80%. 3. Setting a large number of dense meshes on the top and side walls of the box does not help reduce buoyancy; on the contrary, it makes it easier for concrete to flow into the permeable box, affecting structural safety. 4. For permeable boxes, when the bottom mesh is large enough, buoyancy is only generated when the vibrator is in action, and the buoyancy is only generated within the influence range of the vibrator; when the vibrator stops vibrating, the buoyancy value of the permeable box can be zero.

[0006] The purpose of this invention is to provide a hollow slab technology that minimizes the buoyancy of the filling material during concrete pouring, ensures the quality of concrete pouring, and simplifies the anti-buoyancy construction process. Based on experimental research, to achieve the above objective, the technical solution adopted in this invention is: a hollow slab filled with a vented box and equipped with a movable counterweight. The hollow slab includes an upper slab, a lower slab, a vented box, concrete, and a movable counterweight. The upper slab, lower slab, and vented box are all poured within the concrete. The vented box is located between the upper and lower slabs, with solid ribs between adjacent vented boxes. The upper and lower parts of the vented box are the upper and lower flanges of the hollow slab, respectively. A venting mesh is installed at the bottom of the vented box, with dense mesh openings ≥4mm and ≤15mm wide. Gaps or vent holes are present on the sides or top of the vented box. During concrete pouring, when a vibrator is used to vibrate the solid ribs or upper flange concrete, a movable counterweight is provided on the upper part of the upper slab within the area affected by the vibrator. The movable counterweight can be removed after each area has been vibrated. A ventilated mesh with a dense mesh size of ≥4mm and ≤15mm is installed at the bottom of the ventilated box. Gaps or vents on the sides or top of the ventilated box prevent pressure differences between the inside and outside, thus reducing buoyancy. The absence of a large number of dense meshes on the top and side walls prevents concrete from flowing into the ventilated box and affecting structural safety. According to concrete materials science, concrete is a liquid before its initial setting (generally 2-4 hours). Even though the ventilated box reduces theoretical buoyancy, Archimedes' principle still applies. My research results also verify that as long as the concrete remains in a liquid state, regardless of vibration, the buoyancy value of a conventional filling box remains unchanged, meaning Archimedes' principle is fully effective. However, my research also reveals that for ventilated slabs, Archimedes' principle only applies to concrete under dynamic conditions (i.e., when the vibrating device is vibrating), and the effective area is limited to a very small range within the influence area of ​​the vibrating device (in my experiments, the influence area of ​​the vibrating device is related to its size and power; for example, the influence radius of a 30mm vibrating rod is ≤600mm, the influence radius of a 50mm vibrating rod is ≤1000mm, and the influence radius of a plate vibrator is larger). Therefore, during the concrete pouring of the hollow slab of this invention, when the vibrating device vibrates the solid ribs or upper flange concrete, a movable counterweight is provided on the upper part of the slab within its influence area. The movable counterweight can be removed after each area is vibrated. This counterweight is a movable load with a short duration and a small range of action.

[0007] The key feature of this invention is that when concrete is poured into hollow slabs, the movable counterweight can move with the vibrating device. Within the influence area of ​​each vibrating device, the weight of the movable counterweight is ≥ 10% and ≤ 50% of the theoretical buoyancy of the filling material in the hollow slab within that area. Since the movable counterweight can move with the vibrating device, only one set of movable counterweight is needed for each vibrating device, significantly reducing counterweight costs. According to Archimedes' principle, theoretical buoyancy = filling box volume * concrete density - filling box self-weight. For ordinary hollow slabs, the counterweight must be greater than 100% of the theoretical buoyancy of the filling box to ensure the filling material does not float. However, my research shows that, under the premise of ensuring concrete pouring quality, the measured buoyancy of the venting box during concrete vibration can be reduced by up to 80% compared to the theoretical buoyancy value. Therefore, the counterweight only needs to be greater than 20% of the theoretical buoyancy of the venting box to prevent the venting box from floating. Considering that the self-weight of the reinforcing steel bars on the hollow slab is equivalent to a permanent counterweight, the lower limit of the movable counterweight value is taken as 10% of the theoretical buoyancy. When the mesh size of the venting box is small and the buoyancy reduction state is not optimal, and considering the impact force of the vibrator during vibration, the upper limit of the counterweight is set to 50% of the theoretical buoyancy.

[0008] The invention is characterized by the movable counterweight being a rolling cylindrical object. This rolling cylindrical object facilitates the rapid movement of the movable counterweight on the hollow slab, improving construction efficiency.

[0009] The invention is characterized by a handle on the movable counterweight, allowing for free movement of the counterweight on the plate by applying external force to the handle. Whether the movable counterweight is round, rectangular, or of other shapes, adding a handle facilitates operator movement and improves construction efficiency.

[0010] The invention is characterized in that the breathable mesh at the bottom of the breathable box is made of metal or plastic. The metal breathable mesh can be made of wire mesh, expanded metal mesh, or open mesh; the plastic breathable mesh is usually made of plastic mesh.

[0011] The invention is characterized by a modular structure for the ventilated box. The top and side panels of the ventilated box are made of metal, cement, calcium silicate, or plastic. At least two different panels have gaps at their joints. For the modular ventilated box, even if the different panels are folded from the same piece of material, a maximum of four panels can be directly connected, and at most three connecting lines between the panels can be sealed. Gaps will inevitably exist at other joints of the different panels unless they are sealed with sealant. These gaps ensure that the interior of the ventilated box is connected to the atmosphere, preventing the formation of air pressure differences that would affect the buoyancy reduction effect.

[0012] The invention is characterized in that the top and side panels of the venting box are integrally cast from a mold. The top and side panels are made of plastic. The top panel has vent holes, and each vent hole has at least one mesh opening, with a mesh width ≥1mm and ≤8mm. For a venting box with integrally cast top and side panels, the upper structure has excellent sealing. To eliminate pressure differences, dedicated vent holes are necessary. Mesh openings are provided at the locations corresponding to the vent holes. The mesh material can be the same as the top panel material, cast simultaneously; alternatively, the mesh material can be other materials. During venting box fabrication, the mesh is installed inside, within, or outside the vent holes. The mesh width of ≥1mm and ≤8mm ensures airflow while preventing severe concrete leakage.

[0013] The present invention is characterized by a chamfer or bevel at the top or bottom of the venting box. Eliminating the right angle at the top of the venting box can reduce the degree of stress concentration in the concrete inside the hollow slab, and the chamfer or bevel at the bottom of the venting box facilitates the compaction of the concrete at the bottom of the venting box.

[0014] The present invention discloses a construction method for a hollow slab filled with a vented box and a movable counterweight: the hollow slab includes an upper slab, a lower slab, a vented box, concrete, and a movable counterweight. The upper slab, lower slab, and vented box are all cast within the concrete. The vented box is located between the upper and lower slabs, and a solid rib is placed between adjacent vented boxes. The upper and lower parts of the vented box are the upper and lower flanges of the hollow slab, respectively. A venting mesh is installed at the bottom of the vented box. The venting mesh has dense mesh with a mesh width ≥4mm and ≤15mm. There are gaps or vent holes on the side or top of the vented box. During the concrete pouring of the hollow slab, when the vibrating device vibrates the concrete of the solid ribs or upper flange, a movable counterweight is placed on the upper part of the upper slab within the area affected by the vibrating device. The movable counterweight can be removed after each area is vibrated.

[0015] The present invention provides a construction method for a hollow slab filled with a ventilated box and a movable counterweight, characterized in that when the hollow slab is poured with concrete, the movable counterweight can move with the movement of the vibrating device. Within the influence area of ​​each vibrating device, the weight of the movable counterweight is ≥ 10% of the theoretical buoyancy of the filling material in the hollow slab within that area, and ≤ 50% of the theoretical buoyancy.

[0016] By adopting the above solution, the present invention has the following beneficial effects compared with the prior art:

[0017] This invention discloses a hollow slab with a movable counterweight filled with a permeable box. Compared to conventional hollow slabs with filling boxes, it avoids drilling holes in the formwork, eliminating the need for cumbersome anti-buoyancy construction processes, thus saving construction costs and accelerating construction speed. Compared to hollow slabs with permeable boxes that do not require any anti-buoyancy measures, although the movable counterweight is added, the increased workload is minimal, while preventing concrete leakage and better ensuring structural safety. This invention's hollow slab with a movable counterweight filled with a permeable box has a large span, is lightweight, has high construction efficiency, and good structural reliability. This invention has excellent economic efficiency and applicability, and promotes the development of building technology. (iv) Description of the attached drawings

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 This is a vertical cross-sectional view of the hollow plate of the present invention.

[0020] Figure 2 This is a plan view of the air-permeable mesh inside the air-permeable box.

[0021] Figure 3 This is a plan view of the expanded network.

[0022] Figure 4 This is a side view of the assembled ventilation box.

[0023] Figure 5 This is a vertical cross-sectional view of a monolithic cast-in-place ventilated box.

[0024] Figure 6 This is a schematic diagram of the area affected by the vibrator.

[0025] Figure 7 This is a schematic diagram of a cylindrical movable counterweight structure.

[0026] Figure 8 This is a schematic diagram of a rectangular movable counterweight structure.

[0027] Figure 9 This is a schematic diagram showing a vent box with chamfered or beveled edges.

[0028] In the diagram: 1. Hollow slab, 2. Upper plate reinforcement, 3. Lower plate reinforcement, 4. Ventilation box, 5. Concrete, 6. Movable counterweight, 7. Solid rib, 8. Upper flange, 9. Lower flange, 10. Ventilation mesh, 11. Mesh, 12. Gap, 13. Vent hole, 14. Vibrator, 15. Affected area, 16. Handle, 17. Top panel, 18. Side panel, 19. Chamfer, 20. Bevel. (V) Detailed Implementation

[0029] This invention is implemented in the following manner:

[0030] exist Figures 1-6In the illustrated embodiment, a hollow slab with a movable counterweight is filled with a venting box. The hollow slab (1) includes an upper plate (2), a lower plate (3), a venting box (4), concrete (5), and a movable counterweight (6). The upper plate, lower plate, and venting box are all cast in concrete. The venting box is located between the upper plate and the lower plate. There are solid ribs (7) between adjacent venting boxes. The upper and lower parts of the venting box are the upper flange (8) and lower flange (9) of the hollow slab, respectively. The bottom of the air box is equipped with a breathable net (10), which has dense mesh (11) with a mesh width ≥4mm and ≤15mm. There are gaps (12) or vent holes (13) on the side or top of the air box. During the concrete pouring of the hollow slab, when the vibrating device (14) vibrates the solid rib or upper flange concrete, a movable counterweight is provided on the upper part of the slab iron in the area affected by the vibrating device (15). The movable counterweight can be removed after each area is vibrated.

[0031] exist Figure 1 , Figure 6 In the embodiment shown, when the hollow slab (1) is filled with concrete (5), the movable counterweight (6) can move with the movement of the vibrating device (14). Within the influence area (15) of each vibrating device, the weight of the movable counterweight is ≥ 10% of the theoretical buoyancy of the filling material in the hollow slab within that area, and ≤ 50% of the theoretical buoyancy.

[0032] exist Figure 1 , Figure 7 In the embodiment shown, the movable counterweight (6) is a cylindrical object that can roll.

[0033] exist Figure 1 , Figure 7 , Figure 8 In the embodiment shown, the movable counterweight (6) has a handle (16), and by applying an external force to the handle, the movable counterweight can move freely on the iron plate (2).

[0034] exist Figures 1-5 , Figure 9 In the embodiment shown, the breathable mesh (10) at the bottom of the breathable box (4) is made of metal or plastic.

[0035] exist Figure 1 , Figure 4 In the embodiment shown, the ventilation box (4) is a modular structure. The top panel (17) and side panel (18) of the ventilation box are made of metal plate, cement board, calcium silicate board or plastic board. There are gaps (12) at the splicing positions of at least two different panels.

[0036] exist Figure 1 , Figure 5 , Figure 9In the embodiment shown, the top panel (17) and side panel (18) of the ventilation box (4) are integrally cast by a mold. The top panel and side panel are made of plastic materials. The top panel is provided with an exhaust hole (13), and the corresponding part of the exhaust hole is provided with no less than one mesh (11). The width of a single mesh is ≥1mm and ≤8mm.

[0037] exist Figure 9 In the illustrated embodiment, the top or bottom of the vent box (4) has a chamfer (19) or a bevel (20).

[0038] exist Figures 1-6 In the embodiment shown, a construction method for a hollow slab filled with a venting box and a movable counterweight is as follows: The hollow slab (1) includes an upper plate (2), a lower plate (3), a venting box (4), concrete (5), and a movable counterweight (6). The upper plate, the lower plate, and the venting box are all cast in concrete. The venting box is located between the upper plate and the lower plate. There are solid ribs (7) between adjacent venting boxes. The upper and lower parts of the venting box are the upper flange (8) and the lower flange (9) of the hollow slab, respectively. A permeable net (10) is installed at the bottom of the permeable box. The permeable net has dense mesh (11) with a mesh width ≥4mm and ≤15mm. There are gaps (12) or vent holes (13) on the side or top of the permeable box. During the concrete pouring of the hollow slab, when the vibrating device (14) vibrates the solid rib or upper flange concrete, a movable counterweight is provided on the upper part of the slab iron in the area affected by the vibrating device (15). The movable counterweight can be removed after each area is vibrated.

[0039] exist Figure 1 , Figure 6 In the embodiment shown, a construction method for a hollow slab filled with a movable counterweight by a ventilated box is as follows: when the hollow slab (1) is poured with concrete (5), the movable counterweight (6) can move with the movement of the vibrating device (14). Within the influence area (15) of each vibrating device, the weight of the movable counterweight is ≥ 10% of the theoretical buoyancy of the filling material in the hollow slab within that area, and ≤ 50% of the theoretical buoyancy.

Claims

1. A hollow core slab filled with air-entraining boxes with movable weights, which hollow core slab (1) comprises a top slab iron (2), a bottom slab iron (3), air-entraining boxes (4), concrete (5) and movable weights (6), the slab iron, the bottom slab iron and the air-entraining boxes being cast in the concrete, characterized in that The air-permeable box is located between the upper iron sheet and the lower iron sheet, and the adjacent air-permeable boxes are solid ribs (7), the upper and lower parts of the air-permeable box are the upper flange (8) and the lower flange (9) of the hollow slab respectively, the air-permeable net (10) is installed at the bottom of the air-permeable box, the air-permeable net has dense meshes (11) and 4mm≤mesh width≤15mm, there are gaps (12) or exhaust holes (13) on the side or top of the air-permeable box, during the pouring of the hollow slab, the movable counterweight is arranged on the upper part of the upper iron sheet in the influence area (15) of the vibrating device (14) when the vibrating device vibrates the solid rib or the upper flange concrete, the movable counterweight can be removed after the vibration of each area is completed, the movable counterweight can move with the vibrating device when the hollow slab is poured, and in the influence area of each vibrating device, the weight of the movable counterweight is 10% of the theoretical buoyancy of the filling material in the hollow slab≤the weight of the movable counterweight≤50% of the theoretical buoyancy.

2. A hollow core slab filled with a vented box with a movable counterweight according to claim 1, characterized in that The movable counterweight (6) is a cylindrical object capable of rolling.

3. A hollow core slab filled with air-ventilated boxes with movable counterweights according to claim 1, characterized in that A handle (16) is arranged on the movable counterweight (6), and the movable counterweight can move freely on the upper iron sheet (2) by applying an external force to the handle.

4. A hollow core slab filled with air-ventilated boxes with movable counterweights according to claim 1, characterized in that The air-permeable net (10) at the bottom of the air-permeable box (4) is made of metal or plastic.

5. A hollow core slab filled with air-ventilated boxes with movable counterweights according to claim 1, characterized in that The air-permeable box (4) is a spliced structure, the top panel (17) and the side panel (18) of the air-permeable box are made of metal plates or cement plates or silica-calcium plates or plastic plates, and there are gaps (12) at the splicing positions of at least two different panels.

6. A hollow core slab filled with air-ventilated boxes with movable counterweights according to claim 1, characterized in that The top panel (17) and the side panel (18) of the air-permeable box (4) are integrally formed by a mold, and the top panel and the side panel are made of plastic materials, the exhaust holes (13) are arranged on the top panel, and there are not less than one mesh (11) at the corresponding position of the exhaust hole, the width of a single mesh is greater than or equal to 1mm and less than or equal to 8mm.

7. A hollow core slab filled with air-ventilated boxes with movable counterweights according to claim 1, characterized in that The top or bottom of the air-permeable box (4) has a cut corner (19) or a chamfer (20).

8. A construction method for filling a hollow slab with a movable counterweight using a ventilated box, as described in claim 1, characterized in that... The hollow slab (1) comprises an upper iron sheet (2), a lower iron sheet (3), an air-permeable box (4), concrete (5) and a movable counterweight (6), the upper iron sheet, the lower iron sheet and the air-permeable box are poured in the concrete, the air-permeable box is located between the upper iron sheet and the lower iron sheet, the adjacent air-permeable boxes are solid ribs (7), the upper and lower parts of the air-permeable box are the upper flange (8) and the lower flange (9) of the hollow slab respectively, the air-permeable net (10) is installed at the bottom of the air-permeable box, the air-permeable net has dense meshes (11) and 4mm≤mesh width≤15mm, there are gaps (12) or exhaust holes (13) on the side or top of the air-permeable box, during the pouring of the hollow slab, the movable counterweight is arranged on the upper part of the upper iron sheet in the influence area (15) of the vibrating device (14) when the vibrating device vibrates the solid rib or the upper flange concrete, the movable counterweight can be removed after the vibration of each area is completed, the movable counterweight can move with the vibrating device when the hollow slab is poured, and in the influence area of each vibrating device, the weight of the movable counterweight is 10% of the theoretical buoyancy of the filling material in the hollow slab≤the weight of the movable counterweight≤50% of the theoretical buoyancy.

Images