Gas film steel bar truss large-size cavity non-dismantling formwork construction method

Abstract

The invention discloses a gas film steel bar truss large-size cavity non-dismantling formwork construction method, and particularly relates to the field of construction methods. The construction process comprises the steps of inflating the pneumatic membrane, spraying a polyurethane layer on the outer side of the pneumatic membrane, manufacturing and installing the steel bar truss, binding longitudinal steel bars of the steel bar truss, spraying a concrete structural layer in a layered manner, hoisting a non-dismantling formwork, binding and fixing the non-dismantling formwork, and pouring concrete. By the adoption of the technical scheme, the problems that when an existing gas film reinforced concrete building has a large-span structure, the thickness and the dead weight of a reinforced concrete layer are large, and assembly type construction is not facilitated are solved, operation is convenient and fast, and the construction progress is accelerated while the construction quality is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of construction methods, and in particular to a construction method for a large-size cavity non-disassembly formwork of an air-film steel bar truss. Background Art

[0002] The existing air film formwork construction method is to process and shape the air film formwork in the factory according to the engineering design requirements, transport the air film formwork to the construction site after the processing, unfold the air film formwork and fix it on the ring wall, inflate the air film and keep the internal air pressure of the air film stable, spray polyurethane foam on the inner surface of the air film formwork to form a polyurethane layer, then tie the steel bars, and then spray concrete. When the concrete reaches the designed strength, turn off the inflation fan.

[0003] Although the air membrane reinforced concrete structure is strong and durable, it is difficult to construct a large-span structure. When the span of the air membrane reinforced concrete building is constructed as a large-span structure, the thickness and weight of the reinforced concrete layer are large, which is not conducive to prefabricated construction. Summary of the invention

[0004] The present invention aims to provide a method for constructing large-size hollow formwork of air-film reinforced concrete trusses without requiring disassembly, which solves the problem that when existing air-film reinforced concrete buildings have large-span structures, the thickness and self-weight of the reinforced concrete layer are heavy, which is not conducive to prefabricated construction.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows: A construction method of a large-size cavity non-disassembly formwork for an air-film steel bar truss comprises the following steps:

[0006] S1. Prefabricate the air membrane according to the design requirements, transport the air membrane to the construction site and fix it on a flat concrete foundation, then inflate the membrane and maintain a constant pressure inside the membrane;

[0007] S2, spraying polyurethane foam on the surface of the air film;

[0008] S3. Install the steel truss according to the design requirements. The steel truss includes a transverse steel truss and a vertical steel truss. Both are welded by an upper chord steel bar, two lower chord steel bars and web steel bars on both sides. The two sections of the transverse steel truss are extended to a certain length, and the steel bars at the lower end of the vertical steel truss are extended to a certain length to facilitate fixation with the surrounding structure. The extension length is determined according to the design requirements.

[0009] S4. The web steel bars on both sides of the steel truss are "Z" or "V" shaped. After welding, the outer surface of the prefabricated air membrane sprayed with polyurethane foam layer is used as the reference plane. The lower chord steel bars are parallel to the outer surface of the air membrane and bonded to the polyurethane layer. The steel trusses are evenly arranged at equal intervals in the horizontal direction. The longitudinal steel bars are welded or tied between the trusses. The mid-span position of the vertical steel truss should be effectively welded to the main reinforcement of the wall or the tension screw of the other side formwork;

[0010] S5. When the span of the project is large, the concrete structural layer is sprayed, and the structural layer needs to be equipped with steel bars. After the concrete structural layer is sprayed, concrete curing is carried out;

[0011] S6. After the concrete structure layer hardens and forms a certain rigidity, hoist the non-dismantling formwork to the reserved holes and adjust the position, connect the steel bars extending from the vertical steel trusses to the building foundation structure; connect the extended part of the horizontal steel trusses to the building; then pour reinforced concrete around the non-dismantling formwork, and then pour reinforced concrete on the top.

[0012] Furthermore, in step S2, the polyurethane layer sprayed on the surface of the air film should be sprayed in layers, and needs to be sprayed 3-4 times to reach the designed thickness, and the total thickness should be ≥50mm.

[0013] Furthermore, in step S3, the diameter of the steel bars used in the steel trusses and the longitudinal connecting steel bars should not be less than 12 mm.

[0014] Furthermore, in step S5, the surface is cleaned before spraying the concrete structural layer, and the concrete spraying adopts the following steps:

[0015] S5.1. For shotcrete, concrete is transported to the working surface by concrete delivery trucks. Water is added before concrete pumping to moisten and lubricate the pump pipe. Concrete mixing should be longer than 15 minutes. Fine aggregate should not have particles larger than 10 mm. Coarse aggregate should be continuously graded, and the maximum particle size should not be larger than 15 mm.

[0016] S5.2. Before concrete spraying, spray water on the inner layer of concrete 1 hour in advance to enhance effective bonding; the air compressor supply pressure is not less than 0.8Mpa, and the outlet air duct pressure is not less than 0.04Mpa; during the construction process, keep the air supply duct closed and unobstructed, and there are no leaks to reduce the air pressure;

[0017] S5.3. The spray gun should be perpendicular to the sprayed surface. During the spray operation, the up and down swing of the spray gun should be within the range of -5° to +45°, and the distance between the spray gun and the sprayed surface should be maintained at 0.8 to 1m;

[0018] S5.4. The sprayer should keep the spray gun in good working condition, and rotate it stably in a series of small elliptical or circular lines with small spirals, with the last circle pressing 1 / 3 of the previous circle; when the spraying thickness is less than 60mm, use "S" shape movement, the vertical spraying movement range shall not exceed 1m, and the horizontal overlap shall be 1 / 3, and the small elliptical or circular line shall be moved;

[0019] S5.5. After the concrete spraying is completed, the nozzle should be cleaned carefully. The sprayer should always keep the nozzle in good working performance and control the flatness of the concrete surface. After the concrete is initially set, the excess material should be removed with a scraper, and then the spraying or plastering slurry should be used for leveling.

[0020] S5.6. The air film cannot support all shotcrete. The thickness of shotcrete needs to be strictly controlled layer by layer. A thickness ruler is made and tied firmly to the steel mesh. Usually each layer is 6-30mm thick. After each layer hardens and forms a certain rigidity, the next layer can be shot.

[0021] S5.7. Starting from 2 hours after the final setting of the shotcrete, the shotcrete shall be subjected to 24-hour uninterrupted wet curing. Continuous watering can be used for this purpose. Natural curing is used to ensure that the indoor ambient temperature is higher than 10°C and the relative humidity is greater than 70%. The curing period shall be no less than 7 days.

[0022] S5.8. The total thickness of shotcrete shall be determined according to the design requirements and shall not exceed the height of the steel truss.

[0023] Furthermore, the steel truss is divided into a transverse steel truss and a vertical steel truss. The transverse steel truss selects an appropriate steel bar length according to the size of the air membrane and the design requirements. The steel truss is composed of two lower chord steel bars, one upper chord steel bar and web steel bars on both sides. The web steel bars on both sides are tied or welded to the steel bars in a "Z" or "V" shape. The steel truss is then placed on the surface of the polyurethane layer through a concrete pad, requiring the lower chord to be parallel to the surface of the polyurethane layer to form an overall frame of the steel truss.

[0024] Compared with the prior art, this solution has the following beneficial effects:

[0025] This solution can be used for civil and industrial buildings. The air membrane structure is prefabricated in the factory and installed on site, and has the characteristics of fast factory processing speed, easy transportation and installation. Compared with the reinforced concrete structure of the air membrane, the use of steel trusses to replace part of the reinforced concrete effectively improves the load-bearing capacity of the air membrane structure, reduces the dead weight of the structure, enhances the bending resistance, and makes large-span air membrane structures possible. By adopting the on-site installation method, the size of the steel trusses can be adjusted according to the actual use of the building, and the internal formwork-free system of the building can be quickly constructed. The removal process of the reserved hole formwork is optimized to ensure the construction quality while reducing the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a large-size cavity non-disassembly formwork construction method of an air film steel bar truss of the present invention;

[0027] Figure 2 yes Figure 1 Left view of

[0028] Figure 3 is a schematic diagram of a three-dimensional structure of a steel bar truss in an embodiment;

[0029] Figure 4 is a schematic diagram of a steel bar truss being fixed to the outer layer of the air membrane in an embodiment;

[0030] Figure 5 It is a schematic diagram of a three-dimensional structure fixed on a building in an embodiment. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below through specific embodiments:

[0032] The figure numbers in the drawings of the specification include: 1-air membrane; 2-vertical steel truss; 3-transverse steel truss; 4-vertical steel truss extension; 5-polyurethane foam layer; 6-transverse steel truss extension; 7-reinforced concrete structure of the bottom floor of the building.

[0033] Example

[0034] like Figures 1 to 5 As shown, a method for constructing a large-size cavity non-disassembly formwork for an air-film steel bar truss comprises the following steps:

[0035] S1. Prefabricate the air membrane size according to the design requirements, transport the air membrane to the construction site and fix it on a flat concrete foundation to prevent the membrane material from being damaged during the membrane expansion process; then inflate the membrane and maintain a constant pressure state inside the membrane.

[0036] S2. Spray polyurethane foam on the surface of the air film to make the air model have a certain rigidity and help the adhesion of the air model and concrete. The polyurethane layer sprayed on the surface of the air film should be sprayed in layers, and it needs to be sprayed 3-4 times to the designed thickness, and the total thickness should be ≥50mm.

[0037] S3. Install the steel truss according to the design requirements. The steel truss includes the transverse steel truss and the vertical steel truss. The diameter of the steel bars used in the steel truss and the longitudinal connecting steel bars should not be less than 12mm. Both are welded by an upper chord steel bar, two lower chord steel bars and the web steel bars on both sides. The two sections of the transverse steel truss extend part of the length, and the steel bars at the lower end of the vertical steel truss extend part of the length to facilitate fixation with the surrounding structure. The extension length is determined according to the design requirements.

[0038] S4. The web reinforcements on both sides of the steel truss are of "Z" or "V" type. After welding, the outer surface of the prefabricated air membrane sprayed with polyurethane foam layer is used as the reference plane. The lower chord reinforcement is parallel to the outer surface of the air membrane and bonded to the polyurethane layer. The steel trusses are evenly arranged at equal intervals in the horizontal direction. The longitudinal steel bars are welded or tied between the trusses. The mid-span position of the vertical steel truss should be effectively welded to the main reinforcement of the wall or the tension screw of the other side of the formwork to prevent lateral instability of the formwork.

[0039] S5. When the span of the project is large, the concrete structural layer is sprayed. The structural layer needs to be equipped with steel bars. After the concrete structural layer is sprayed, the concrete is cured. Before the concrete structural layer is sprayed, the surface is cleaned. The concrete spraying adopts the following steps:

[0040] S5.1. For shotcrete, concrete is transported to the working surface by concrete delivery trucks. Water is added before concrete pumping to moisten and lubricate the pump pipe. Concrete mixing should be longer than 15 minutes. Fine aggregate should not have particles larger than 10 mm. Coarse aggregate should be continuously graded, and the maximum particle size should not be larger than 15 mm.

[0041] S5.2. Before concrete spraying, spray water on the inner layer of concrete 1 hour in advance to enhance effective bonding; the air compressor supply pressure is not less than 0.8Mpa, and the outlet air duct pressure is not less than 0.04Mpa; during the construction process, keep the air supply duct closed and unobstructed, and there are no leaks to reduce the air pressure;

[0042] S5.3. The spray gun should be perpendicular to the sprayed surface. During the spray operation, the up and down swing of the spray gun should be within the range of -5° to +45°, and the distance between the spray gun and the sprayed surface should be maintained at 0.8 to 1m;

[0043] S5.4. The sprayer should keep the spray gun in good working condition, and rotate it stably in a series of small elliptical or circular lines with small spirals, with the last circle pressing 1 / 3 of the previous circle; when the spraying thickness is less than 60mm, use "S" shape movement, the vertical spraying movement range shall not exceed 1m, and the horizontal overlap shall be 1 / 3, and the small elliptical or circular line shall be moved;

[0044] S5.5. After the concrete spraying is completed, the nozzle should be cleaned carefully. The sprayer should always keep the nozzle in good working performance and control the flatness of the concrete surface. After the concrete is initially set, the excess material should be removed with a scraper, and then the spraying or plastering slurry should be used for leveling.

[0045] S5.6. The air film cannot support all shotcrete. The thickness of shotcrete needs to be strictly controlled layer by layer. A thickness ruler is made and tied firmly to the steel mesh. Usually each layer is 6-30mm thick. After each layer hardens and forms a certain rigidity, the next layer can be shot.

[0046] S5.7. Starting from 2 hours after the final setting of the shotcrete, the shotcrete shall be subjected to 24-hour uninterrupted wet curing. Continuous watering can be used for this purpose. Natural curing is used to ensure that the indoor ambient temperature is higher than 10°C and the relative humidity is greater than 70%. The curing period shall be no less than 7 days.

[0047] S5.8. The total thickness of shotcrete shall be determined according to the design requirements and shall not exceed the height of the steel truss.

[0048] S6. After the concrete structure layer hardens and forms a certain rigidity, hoist the non-dismantling formwork to the reserved holes and adjust the position, connect the steel bars extending from the vertical steel trusses to the building foundation structure; connect the extended part of the horizontal steel trusses to the building; then pour reinforced concrete around the non-dismantling formwork, and then pour reinforced concrete on the top.

[0049] In this embodiment, the main components are a prefabricated air membrane 1, a polyurethane layer 5, a vertical steel truss 2, a transverse steel truss 3 and a concrete structural layer; the vertical steel truss 2 and the transverse steel truss 3 are welded into a frame; the lower surface of the lower chord of the steel truss is placed on the polyurethane layer 5 through a concrete pad, and the steel truss is connected to the air membrane 1 and the polyurethane layer 5 through the concrete structural layer to form a whole and bear the force together; the upper chord steel bars and the lower chord steel bars are welded or tied to the belly steel bars on both sides; the two sections 6 of the transverse steel truss extend beyond the non-dismantling formwork, and the lower end 4 of the vertical steel truss extends beyond the non-dismantling formwork, so that the end extension steel bars of the steel truss and the steel bars of the components connected thereto are effectively overlapped, and the extended length of the steel truss is determined according to the design requirements.

[0050] According to the size of the air film, a transverse steel truss and a vertical steel truss are manufactured; the transverse steel truss and the vertical steel truss are laid on the upper reference surface of the welding platform of the welding equipment, and are spliced ​​into a frame, and then the welding equipment is started to weld to form a prefabricated single steel truss;

[0051] Prefabricated integral steel truss Figure 5 : The prefabricated single steel truss is transferred to the prefabricated air membrane station, and the steel truss is placed on the upper surface of the prefabricated air membrane coated with polyurethane on the reference platform of this station, and then tied or welded to make the prefabricated integral formwork and the steel truss relatively fixed, and the spacing of the truss frame is determined according to the design requirements.

[0052] The large-size hollow non-dismantling formwork construction method of the air-film steel bar truss in the present invention is characterized in that the lower chord steel bars of the steel bar truss are all parallel and evenly distributed, forming a triangular grid with the upper chord steel bars, with reasonable force distribution and beautiful appearance; only a small amount of longitudinal or longitudinal steel bars are appropriately arranged at both ends of the air-film steel bar truss concrete non-dismantling formwork structure in the present invention, which can reduce the use of steel bars as much as possible while achieving reasonable force distribution, thereby reducing the dead weight and construction cost of the air-film structure.

[0053] The present invention can produce a more advanced and more scientific air film steel bar truss concrete non-disassembly formwork structure and its construction method. The construction process is as follows: the air film is prefabricated and processed in the factory, transported to the site and formed by blower film blowing, and placed horizontally on the flat ground → spray polyurethane on the outside of the air film to form an insulation layer → prefabricate the steel bar truss frame according to the size of the air film, including transverse steel bar trusses and longitudinal steel bar trusses, and tie and weld steel bars on the steel bar trusses → weld the transverse steel bar trusses and longitudinal steel bar trusses into a frame, and the lower surface of the welded prefabricated integral formwork is two lower chords parallel to the plane of the air film → tie longitudinal steel bars between parallel steel bar truss beams → use a spray gun to spray concrete in layers to the steel bar truss to form a concrete structural layer → form a kind of air film steel bar truss concrete non-disassembly formwork structure. This new type of non-disassembly formwork is transported to the site and stored → hoisted → temporary support installation → wall steel bar tying and pipeline laying → acceptance → wall concrete pouring. So far, the embodiment is used as a permanent non-disassembly formwork for the central hole of a multi-story or high-rise building, and it bears the external load together with the cast-in-place wall, thereby becoming a part of the building wall.

[0054] The above are only embodiments of the present invention, and the common knowledge such as the known specific structures and / or characteristics in the scheme are not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for constructing a large-size cavity non-disassembly formwork of an air-film steel bar truss, characterized in that: The steps include: S1. Prefabricate the air membrane according to the design requirements, transport the air membrane to the construction site and fix it on a flat concrete foundation, then inflate the membrane and maintain a constant pressure inside the membrane; S2, spraying polyurethane foam on the surface of the air film; S3. Install the steel truss according to the design requirements. The steel truss includes a transverse steel truss and a vertical steel truss. Both are welded by an upper chord steel bar, two lower chord steel bars and web steel bars on both sides. The two sections of the transverse steel truss are extended to a certain length, and the steel bars at the lower end of the vertical steel truss are extended to a certain length to facilitate fixation with the surrounding structure. The extension length is determined according to the design requirements. S4. The web steel bars on both sides of the steel truss are "Z" or "V" shaped. After welding, the outer surface of the prefabricated air membrane sprayed with polyurethane foam layer is used as the reference plane. The lower chord steel bars are parallel to the outer surface of the air membrane and bonded to the polyurethane layer. The steel trusses are evenly arranged at equal intervals in the horizontal direction. The longitudinal steel bars are welded or tied between the trusses. The mid-span position of the vertical steel truss should be effectively welded to the main reinforcement of the wall or the tension screw of the other side formwork; S5. When the span of the project is large, the concrete structural layer is sprayed, and the structural layer needs to be equipped with steel bars. After the concrete structural layer is sprayed, concrete curing is carried out; S6. After the concrete structural layer hardens and forms a certain rigidity, the non-disassembly formwork is hoisted to the reserved hole and adjusted to the position, and the steel bars extending from the vertical steel truss are connected to the building foundation structure; the extended part of the horizontal steel truss is connected to the building; Then, reinforced concrete is poured around the non-removal formwork, followed by reinforced concrete pouring on the top.

2. The method for constructing a large-size cavity non-disassembly formwork of an air-film steel bar truss according to claim 1, characterized in that: In step S2, the polyurethane layer sprayed on the surface of the air film should be sprayed in layers, and it needs to be sprayed 3-4 times to reach the designed thickness, and the total thickness should be ≥50mm.

3. The method for constructing a large-size cavity non-disassembly formwork of an air-film steel bar truss according to claim 1, characterized in that: In step S3, the diameter of the steel bars used in the steel trusses and the longitudinal connecting steel bars should not be less than 12 mm.

4. The method for constructing a large-size cavity non-disassembly formwork of an air-film steel bar truss according to claim 1, characterized in that: In step S5, the surface is cleaned before spraying the concrete structure layer. The concrete spraying adopts the following steps: S5.

1. For shotcrete, concrete is transported to the working surface by concrete delivery trucks. Water is added before concrete pumping to moisten and lubricate the pump pipe. Concrete mixing should be longer than 15 minutes. Fine aggregate should not have particles larger than 10 mm. Coarse aggregate should be continuously graded, and the maximum particle size should not be larger than 15 mm. S5.

2. Before concrete spraying, spray water on the inner layer of concrete 1 hour in advance to enhance effective bonding; the air compressor supply pressure is not less than 0.8Mpa, and the outlet air duct pressure is not less than 0.04Mpa; during the construction process, keep the air supply duct closed and unobstructed, and there are no leaks to reduce the air pressure; S5.

3. The spray gun should be perpendicular to the sprayed surface. During the spray operation, the up and down swing of the spray gun should be within the range of -5° to +45°, and the distance between the spray gun and the sprayed surface should be maintained at 0.8 to 1m; S5.

4. The sprayer should keep the spray gun in good working condition, and rotate it stably in a series of small elliptical or circular lines with small spirals, with the last circle pressing 1 / 3 of the previous circle; when the spraying thickness is less than 60mm, use "S" shape movement, the vertical spraying movement range shall not exceed 1m, and the horizontal overlap shall be 1 / 3, and the small elliptical or circular line shall be moved; S5.

5. After the concrete spraying is completed, the nozzle should be cleaned carefully. The sprayer should always keep the nozzle in good working performance and control the flatness of the concrete surface. After the concrete is initially set, the excess material should be removed with a scraper, and then the spraying or plastering slurry should be used for leveling. S5.

6. The air film cannot support all shotcrete. The thickness of shotcrete needs to be strictly controlled layer by layer. A thickness ruler is made and tied firmly to the steel mesh. Usually each layer is 6-30mm thick. After each layer hardens and forms a certain rigidity, the next layer can be shot. S5.

7. Starting from 2 hours after the final setting of the shotcrete, the shotcrete shall be subjected to 24-hour uninterrupted wet curing. Continuous watering can be used for this purpose. Natural curing is used to ensure that the indoor ambient temperature is higher than 10°C and the relative humidity is greater than 70%. The curing period shall be no less than 7 days. S5.

8. The total thickness of shotcrete shall be determined according to the design requirements and shall not exceed the height of the steel truss.

5. The method for constructing a large-size cavity non-disassembly formwork of an air-film steel bar truss according to claim 1, characterized in that: The steel truss is divided into transverse steel truss and vertical steel truss. The transverse steel truss selects the appropriate steel length according to the size of the air membrane and design requirements. The steel truss is composed of two lower chord steel bars, one upper chord steel bar and web steel bars on both sides. The web steel bars on both sides are tied or welded to the steel bars in a "Z" or "V" shape. Then the steel truss is placed on the surface of the polyurethane layer through a concrete pad, and the lower chord is required to be parallel to the surface of the polyurethane layer to form an overall frame of the steel truss.

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