In-situ cast-in-place construction process for pre-tensioning method prestressed arch slab roof of large-span granary

Abstract

The invention discloses an in-situ cast-in-place construction process for a pre-tensioning method prestressed arch slab roof of a large-span granary. Comprising the following steps that S1, a pre-tensioning method pedestal is cast in situ or a prefabricated pre-tensioning method pedestal is used; s2, a pre-tensioning method pedestal is poured; s3, pre-stressed tendons are tensioned through a pre-tensioning method pedestal; s4, building a template of the arch slab roof; s5, dismounting a pre-tensioning method pedestal and a template; an all-round scaffold is erected on the hardened ground in the granary, in-situ cast-in-situ slab construction is carried out, the integrity of the arch slab is guaranteed, and the quality is good; according to the arrangement of a cast-in-place pre-tensioning method pedestal or a prefabricated pre-tensioning method pedestal, the construction quality is ensured, formwork building is conveniently conducted on the arch slab roof, prestressed tendons are installed on the pre-tensioning method pedestal, formwork supporting and fixing are achieved, and due to elastic retraction of the prestressed tendons, the formwork can be fixed through the bonding effect between the prestressed tendons and concrete, the formwork can be fixed, and the formwork can be fixed. And the concrete obtains pre-compressive stress, and the integrity and the high quality of the arch slab roof are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of in-situ cast-in-place arch slab roof, and specifically relates to an in-situ cast-in-place construction process for a large-span granary prestressed arch slab roof by pre-tensioning method. Background Art

[0002] The pre-stressing beam manufacturing process is to tension the prestressed steel bars before pouring concrete, and temporarily anchor the prestressed steel bars on the tensioning pedestal. When the concrete of the component meets the strength and elastic modulus (or age) specified in the design, the prestressed steel bars are gradually relaxed. In this way, the elastic shrinkage of the prestressed steel bars and the bonding effect between them and the concrete will give the concrete prestress.

[0003] There are more and more large-span and large-area construction projects, and their construction is becoming more and more difficult. In order to ensure the construction quality of construction projects and improve their work efficiency, the high-altitude in-situ cast-in-place technology of pre-tensioned prestressed arch slab roof is applied in the construction of construction projects. This technology is not limited by the construction site, and a variety of mechanical equipment is applied to it, which solves the inconvenience problems in the lifting and transportation links, and also reduces the construction cost; however, various large-span pre-tensioned prestressed arch slab roof in-situ cast-in-situ construction processes on the market still have various problems.

[0004] For example, the pre-tensioned prestressed arch slab granary roof in-situ cast-in-place construction method disclosed in the authorization announcement number CN101831978B includes off-site prefabrication of arch slab roof truss partitions and construction of indoor concrete floor of bungalow warehouse, wall masonry and ring beam construction, erection of rack support, arch slab roof truss formwork construction, steel bar layout, tensioning and use of top support rods to adjust the unbalanced force during tensioning, arch slab concrete pouring, mold removal, maintenance, tensioning and other steps. The present invention is simple to construct, easy to control the construction quality, and ensures the construction quality, but it does not solve the existing traditional construction method that usually adopts ground prefabrication and aerial hoisting, which has high requirements on the construction site and is difficult to hoist, and has a long construction period. At the same time, it is very easy to cause damage to the quality of the arch slab during the hoisting process, and water leakage occurs after the installation is completed. For this reason, we propose a large-span granary pre-tensioned prestressed arch slab roof in-situ cast-in-place construction process. Summary of the invention

[0005] The purpose of the present invention is to provide an in-situ cast-in-place construction process for a large-span granary prestressed arch slab roof by pre-tensioning method, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a large-span granary prestressed arch roof in-situ cast-in-place construction process, comprising the following steps:

[0007] S1. Cast-in-place pre-tensioned pedestal or use prefabricated pre-tensioned pedestal: Fix and install partitions on the upper end of the load-bearing columns of the wall and solidify the installed partitions, or fix and install the prefabricated pre-tensioned pedestal with anchor rods;

[0008] S2. Casting of the pre-tensioned pedestal: During the pre-casting, a steel cage is first made, and the steel cage is connected to the load-bearing column through drilling holes, and then the pre-tensioned pedestal is cast. After casting, the pre-tensioned pedestal is solidified and formed;

[0009] S3. Tensioning prestressed tendons through a pre-tensioning pedestal: installing prestressed tendons on the pre-tensioning pedestal, and then straightening the prestressed tendons;

[0010] S4. Formwork construction of the arch roof: Use the hardened ground in the granary to build a full-floor scaffolding, and build the formwork in an arc shape according to the height of the arch roof. Then, build steel bars on the formwork and perform in-situ cast-in-place construction to ensure the integrity of the arch roof.

[0011] S5. Disassembly of the prestressing pedestal and formwork: After the arch slab roof is formed, the prestressed tendons are first released and then retracted. The cast-in-place prestressing pedestal or the prefabricated prestressing pedestal is then disassembled, and finally the formwork is disassembled to complete the pouring of the arch slab roof.

[0012] Furthermore, when the cast-in-place prestressed pedestal and the prefabricated prestressed pedestal in S1 are in use, holes are drilled on the load-bearing columns, and the distance between the holes is set at 10 cm. All the holes are arranged in a matrix to facilitate the installation and connection of the steel cage of the cast-in-place prestressed pedestal, or the connection of the connecting steel bars of the prefabricated prestressed pedestal.

[0013] Furthermore, the prefabricated pre-stressed pedestal is constructed by formwork, and the pier-type pedestal is formed by casting the formwork, and after the formwork is constructed, it is fixedly supported by scaffolding and support beams, and when the prefabricated pre-stressed pedestal is installed, it is also fixedly supported by scaffolding and support beams, so as to maintain the stable connection and installation of the cast-in-place pre-stressed pedestal and the prefabricated pre-stressed pedestal.

[0014] Furthermore, the side formwork and end formwork of the formwork are made of standardized steel formwork. The formwork must be cleaned and evenly coated with a release agent. The formwork must be installed after the steel bars are installed. The formwork is installed using the side-wrapped bottom method. The upper and lower ends are connected with screws, and the formwork is straightened and adjusted with diagonal braces. The gaps between the side formworks, between the side formworks and the bottom formwork, and between the side formworks and the end formworks are sealed with sponge strips, and the formworks are connected with bolts.

[0015] Furthermore, the steel cage in S2 is provided with a middle 8 stirrup every 40 cm and is fastened to the bottom plate steel bars; the internal support of the formwork is supported by a steel bar forming frame, and an air bag is used as the inner mold. To ensure the smooth removal of the inner mold, the inner mold must be cleaned and brushed with a release agent before each use. After the hollow cast-in-place pre-stressed pedestal is cast, the removal time of the air bag is controlled and the air bag is removed in about 4 hours. When removing it, it must be deflated slowly.

[0016] Furthermore, when the cutting length of the S3 prestressed tendons is determined by calculation, the prestressing elongation value, the reserved amount of the head and the reserved amount of the elastic shrinkage value are set to one quarter of the length of the prestressed tendons; when the prestressed tendons are tensioned, the over-tensioning method is adopted to reduce the relaxation loss of the prestressed tendons; when tensioning, tensioning is started from zero stress to 1.05 times the designed tensioning control stress, and after holding the load for 2 minutes, it is anchored and then unloaded.

[0017] Furthermore, the S3 prestressed tendons are straightened by clamping and fixing them with tensioning clamps and anchoring clamps, and straightening of the prestressed tendons is achieved by a through-type jack, an electric screw tensioning machine or a hydraulic jack and a winch. The through-type jack and the hydraulic jack are used to support between the fixed beam and the movable beam, and the electric screw tensioning machine and the winch are used to wind and straighten the prestressed tendons.

[0018] Furthermore, when the formwork of the arch roof in S4 is being constructed, the formwork must be cleaned and evenly coated with a release agent, and the formwork is supported and fixed by a scaffold, and the contact point between the scaffold and the formwork is supported by a 12 mm thick bamboo plywood as a support pad, and when the formwork is spliced, the formwork must be kept to have the same density and flatness.

[0019] Furthermore, the slab pouring construction in S4 should start with the pouring of the lower chord slab, and then the upper line slab should be poured. During the pouring process, since the upper and lower chord slabs are relatively thin, after the concrete pouring is completed, a portable flat plate vibrator is used to vibrate the slurry to ensure the density and integrity of the concrete. After the concrete pouring is completed, a comprehensive inspection is carried out to ensure that there are no cracks or other quality problems in the poured parts. If cracks are found, the concrete must be repaired by a second concrete plastering and pressing. After the concrete solidifies, it should be watered and cured immediately to ensure sufficient moisture and temperature. The curing time should be no less than 7 days.

[0020] Furthermore, the prestressed tendons in S5 are released by sand box relaxation method, jack relaxation method, tensioning relaxation method and oxygen cutting method; and the connecting steel bars of the cast-in-place prestressed pedestal or the prefabricated prestressed pedestal are cut by a cutting machine or oxygen cutting method, the cast-in-place prestressed pedestal or the prefabricated prestressed pedestal is disassembled, and then the formwork is disassembled and removed, and finally the lower surface of the arch roof is filled and repaired by concrete.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The in-situ cast-in-place construction technology of the large-span granary pre-stressed arch slab roof of the present invention utilizes the hardened ground in the granary to set up a full-floor scaffolding to carry out in-situ cast-in-place slab construction, thereby ensuring the integrity of the arch slab and good quality; avoiding the arch slab hoisting and installation link, facilitating on-site safety management and saving construction period; the arrangement of the cast-in-situ pre-stressed pedestal or the use of a prefabricated pre-stressed pedestal ensures the construction quality, and the cast-in-situ pre-stressed pedestal or the use of a prefabricated pre-stressed pedestal is installed and fixed by anchor rods to maintain the stability of the cast-in-situ pre-stressed pedestal or the use of a prefabricated pre-stressed pedestal, which is convenient for formwork construction of the arch slab roof, and prestressed tendons are installed on the pre-stressed pedestal to support and fix the formwork. After pouring, when the concrete of the component meets the strength and elastic modulus specified in the design, the prestressed tendons are gradually relaxed. Due to the elastic shrinkage of the prestressed tendons, the concrete obtains pre-compression stress through the bonding effect between the prestressed tendons and the concrete, thereby improving the integrity and high quality of the arch slab roof. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the steps of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1 The present invention provides a technical solution: a large-span granary prestressed arch roof in-situ cast-in-place construction process, comprising the following steps:

[0026] S1. Cast-in-place pre-tensioned pedestal or use prefabricated pre-tensioned pedestal: Fix and install partitions on the upper end of the load-bearing columns of the wall and solidify the installed partitions, or fix and install the prefabricated pre-tensioned pedestal with anchor rods;

[0027] S2. Casting of the pre-tensioned pedestal: During the pre-casting, a steel cage is first made, and the steel cage is connected to the load-bearing column through drilling holes, and then the pre-tensioned pedestal is cast. After casting, the pre-tensioned pedestal is solidified and formed;

[0028] S3. Tensioning prestressed tendons through a pre-tensioning pedestal: installing prestressed tendons on the pre-tensioning pedestal, and then straightening the prestressed tendons;

[0029] S4. Formwork construction of the arch roof: Use the hardened ground in the granary to build a full-floor scaffolding, and build the formwork in an arc shape according to the height of the arch roof. Then, build steel bars on the formwork and perform in-situ cast-in-place construction to ensure the integrity of the arch roof.

[0030] S5. Disassembly of the prestressing pedestal and formwork: After the arch slab roof is formed, the prestressed tendons are first released and then retracted. The cast-in-place prestressing pedestal or the prefabricated prestressing pedestal is then disassembled, and finally the formwork is disassembled to complete the pouring of the arch slab roof.

[0031] In order to achieve the installation of the cast-in-place prestressed pedestal and the prefabricated prestressed pedestal and maintain the stability of the connection, in the present embodiment, preferably, when the cast-in-place prestressed pedestal and the prefabricated prestressed pedestal in S1 are in use, holes are drilled on the load-bearing columns, and the distance between the holes is set at 10 cm. All the holes are arranged in a matrix to facilitate the installation and connection of the steel cage of the cast-in-place prestressed pedestal, or the connection of the connecting steel bars of the prefabricated prestressed pedestal.

[0032] In order to support and fix the formwork, maintain the stable support of the formwork during pouring, and support and install the cast-in-place pre-stressed pedestal and the prefabricated pre-stressed pedestal, in this embodiment, preferably, the prefabricated pre-stressed pedestal is constructed by formwork, and a pier-type pedestal is formed by pouring the formwork, and after the formwork is constructed, it is fixedly supported by scaffolding and support beams, and when the prefabricated pre-stressed pedestal is installed, it is also fixedly supported by scaffolding and support beams, so as to maintain the stable connection and installation of the cast-in-place pre-stressed pedestal and the prefabricated pre-stressed pedestal.

[0033] In order to install the template and make it easy to disassemble, to seal the gaps between the templates, and to achieve a fixed connection between the templates, in this embodiment, preferably, the side templates and end templates of the template are made of standardized steel templates, the template must be cleaned and evenly coated with a release agent, the template must be installed after the steel bar installation is completed, the template is installed using the side wrapping bottom method, the upper and lower ends are connected with screws, the template is straightened and adjusted with diagonal braces, and the gaps between the side templates and between the side template and the bottom template, and between the side template and the end template are sealed with sponge strips, and the templates are connected with bolts.

[0034] In order to support and fix the steel cage, to realize hollow casting of the cast-in-place pre-stressed pedestal, to reduce the weight of the cast-in-place pre-stressed pedestal, and to facilitate disassembly, in this embodiment, preferably, the steel cage in S2 is provided with a middle 8 stirrup every 40 cm, and is fastened to the bottom plate steel bars; the internal support of the formwork is supported by a steel bar shaping frame, and an air bag is used as the inner mold. To ensure the smooth removal of the inner mold, the inner mold must be cleaned and brushed with a release agent before each use. After the hollow cast-in-place pre-stressed pedestal is cast, the removal time of the air bag is controlled and the air bag is removed in about 4 hours. When removing it, it must be deflated slowly.

[0035] In order to realize the tensioning of prestressed tendons and facilitate the connection and straightening of prestressed tendons, in the present embodiment, preferably, when the cutting length of the S3 tensioning prestressed tendons is determined by calculation, the tensioning elongation value, the reserved amount of the head and the reserved amount of the elastic shrinkage value are set to one quarter of the length of the tensioning prestressed tendons; when tensioning the prestressed tendons, the over-tensioning method is adopted to reduce the relaxation loss of the prestressed tendons; when tensioning, tensioning is started from zero stress to 1.05 times the designed tensioning control stress, and after holding the load for 2 minutes, it is anchored and then unloaded.

[0036] In order to straighten the prestressed tendons and achieve stress support, in this embodiment, preferably, the S3 prestressed tendons are straightened and clamped and fixed by tensioning clamps and anchoring clamps, and the through-type jack, electric screw tensioning machine or hydraulic jack and winch are used to straighten the prestressed tendons, and the through-type jack and hydraulic jack are used to support between the fixed beam and the movable beam, and the electric screw tensioning machine and winch are used to wind and straighten the prestressed tendons.

[0037] In order to realize the installation and support of the formwork of the board roof, and make the formwork of the board roof easy to disassemble, maintain the connectivity between the formworks, and protect the stability of the support, in this embodiment, preferably, when the formwork of the arch board roof in S4 is being built, the formwork must be cleaned and evenly coated with a release agent, and the formwork is supported and fixed by a scaffold, and the contact point between the scaffold and the formwork is supported by a 12 mm thick bamboo plywood as a support pad, and when the formwork is spliced, the formwork must be kept to have the same density and flatness.

[0038] In order to achieve stability casting, the formwork of the board roof is cast from the bottom to the top, and a flat plate vibrator is used to vibrate to maintain the integrity and flatness of the board roof. In this embodiment, preferably, the casting plate construction in S4 should start with the casting of the lower chord plate, and then the upper line plate is cast. During the casting process, since the upper and lower chord plates are relatively thin, after the concrete casting is completed, a portable flat plate vibrator is used to vibrate the concrete to ensure the density and integrity of the concrete. After the concrete casting is completed, a comprehensive inspection is carried out. If there are no cracks or other quality problems in the casting area, cracks must be repaired by re-concrete pressing. After the concrete solidifies, watering and curing should be carried out immediately to ensure sufficient moisture and temperature. The curing time is not less than 7d.

[0039] In order to release the prestressed tendons and repair the arch roof, in this embodiment, preferably, the prestressed tendons in S5 are released by sand box relaxation method, jack relaxation method, tension relaxation method and oxygen cutting method; and the connecting steel bars of the cast-in-place prestressed pedestal or the prefabricated prestressed pedestal are cut off by a cutting machine or oxygen cutting method, the cast-in-place prestressed pedestal or the prefabricated prestressed pedestal is disassembled, and then the formwork is disassembled and removed, and finally the lower surface of the arch roof is filled and repaired with concrete.

[0040] The working principle and use process of the present invention:

[0041] Step 1: Cast-in-place pre-tensioned pedestal or use prefabricated pre-tensioned pedestal: Fix and install partitions on the upper end of the load-bearing columns of the wall, and solidify the installed partitions, or fix and install the prefabricated pre-tensioned pedestal with anchor rods;

[0042] Step 2: Casting of the pre-tensioned pedestal: During the pre-casting, a steel cage is first made, and the steel cage is connected to the load-bearing column through drilling holes, and then the pre-tensioned pedestal is cast. After casting, the pre-tensioned pedestal is solidified and formed;

[0043] Step 3: tensioning the prestressed tendons through the pre-tensioning pedestal: installing the prestressed tendons on the pre-tensioning pedestal, and then straightening the prestressed tendons;

[0044] Step 4: Formwork construction of the arch roof: Use the hardened ground in the granary to build a full-house scaffolding, and build the template in an arc shape according to the height of the arch roof. Then, build steel bars on the template and perform in-situ cast-in-place construction to ensure the integrity of the arch roof.

[0045] Step 5. Dismantle the prestressed pedestal and formwork: After the arch roof is formed, first release the prestressed tendons, then retract the prestressed tendons, and then dismantle the cast-in-place prestressed pedestal or the prefabricated prestressed pedestal, and finally dismantle the formwork to complete the pouring of the arch roof.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. The in-situ cast-in-place construction process of the prestressed arch slab roof of the large-span granary is characterized by: The following steps are included: S1. Cast-in-place pre-tensioned pedestal or use prefabricated pre-tensioned pedestal: Fix and install partitions on the upper end of the load-bearing columns of the wall and solidify the installed partitions, or fix and install the prefabricated pre-tensioned pedestal with anchor rods; S2. Casting of the pre-tensioned pedestal: During the pre-casting, a steel cage is first made, and the steel cage is connected to the load-bearing column through drilling holes, and then the pre-tensioned pedestal is cast. After casting, the pre-tensioned pedestal is solidified and formed; S3. Tensioning prestressed tendons through a pre-tensioning pedestal: installing prestressed tendons on the pre-tensioning pedestal, and then straightening the prestressed tendons; S4. Formwork construction of the arch roof: Use the hardened ground in the granary to build a full-floor scaffolding, and build the formwork in an arc shape according to the height of the arch roof. Then, build steel bars on the formwork and perform in-situ cast-in-place construction to ensure the integrity of the arch roof. S5. Disassembly of the prestressing pedestal and formwork: After the arch slab roof is formed, the prestressed tendons are first released and then retracted. The cast-in-place prestressing pedestal or the prefabricated prestressing pedestal is then disassembled, and finally the formwork is disassembled to complete the pouring of the arch slab roof.

2. The in-situ cast-in-place construction process for the prestressed arched roof of a large-span granary according to claim 1 is characterized by: When the cast-in-place prestressed pedestal and the prefabricated prestressed pedestal in S1 are in use, holes are drilled on the load-bearing columns, and the distance between the holes is set at 10 cm. All the holes are arranged in a matrix to facilitate the installation and connection of the steel cage of the cast-in-place prestressed pedestal, or the connection of the connecting steel bars of the prefabricated prestressed pedestal.

3. The in-situ cast-in-place construction process for the prestressed arched roof of a large-span granary according to claim 2 is characterized by: The prefabricated pre-stressed pedestal is constructed by formwork, and the pier-type pedestal is formed by casting the formwork. After the formwork is constructed, it is fixedly supported by scaffolding and support beams. When the prefabricated pre-stressed pedestal is installed, it is also fixedly supported by scaffolding and support beams to maintain the stable connection and installation of the cast-in-place pre-stressed pedestal and the prefabricated pre-stressed pedestal.

4. The in-situ cast-in-place construction process for the prestressed arched roof of a large-span granary according to claim 3 is characterized by: The side formwork and end formwork of the formwork are both made of standardized steel formwork. The formwork must be cleaned and evenly coated with a release agent. The formwork must be installed after the steel bars are installed. The formwork is installed using the side-wrapped bottom method. The upper and lower ends are connected with screws, and the formwork is straightened and adjusted with diagonal braces. The gaps between the side formworks, between the side formworks and the bottom formwork, and between the side formworks and the end formworks are sealed with sponge strips, and the formworks are connected with bolts.

5. The in-situ cast-in-place construction process for the prestressed arched slab roof of a large-span granary according to claim 1 is characterized by: The steel cage in S2 is provided with a middle 8 stirrup every 40cm, and is fastened to the bottom plate steel bars; the internal support of the formwork is fastened with a steel bar forming frame, and an air bag is used as the inner mold. To ensure the smooth removal of the inner mold, the inner mold must be cleaned and brushed with a release agent before each use. After the hollow cast-in-place pre-stressed pedestal is poured, the removal time of the air bag is controlled and the air bag is removed in about 4 hours. When removing it, deflate it slowly.

6. The in-situ cast-in-place construction process for the prestressed arched slab roof of a large-span granary according to claim 1 is characterized by: When the cutting length of the S3 prestressed tendons is determined by calculation, the tensioning elongation value, the reserved amount of the head and the reserved amount of the elastic shrinkage value are set to one quarter of the length of the prestressed tendons; when tensioning the prestressed tendons, the over-tensioning method is adopted to reduce the relaxation loss of the prestressed tendons; when tensioning, tensioning is started from zero stress to 1.05 times the designed tensioning control stress, and after holding the load for 2 minutes, it is anchored and then unloaded.

7. The in-situ cast-in-place construction process for the prestressed arched slab roof of a large-span granary according to claim 1 is characterized by: The S3 prestressed tendons are straightened by clamping and fixing them with tensioning clamps and anchoring clamps, and straightening is achieved by a through-type jack, an electric screw tensioning machine or an oil hydraulic jack and a winch. The through-type jack and the oil hydraulic jack are used to support between the fixed beam and the movable beam, and the electric screw tensioning machine and the winch are used to wind and straighten the prestressed tendons.

8. The in-situ cast-in-place construction process for the prestressed arched roof of a large-span granary according to claim 1 is characterized by: When constructing the formwork of the arch roof in S4, the formwork must be cleaned and evenly coated with a release agent, and the formwork is supported and fixed by a scaffold, and the contact point between the scaffold and the formwork is supported by a 12 mm thick bamboo plywood as a support pad, and when the formwork is spliced, the formwork must be kept to have the same density and flatness.

9. The in-situ cast-in-place construction process for the prestressed arched roof of a large-span granary according to claim 1 is characterized by: The slab construction in S4 should start with the pouring of the lower chord slab, and then the upper line slab should be poured. During the pouring process, since the upper and lower chord slabs are relatively thin, after the concrete pouring is completed, a portable flat plate vibrator is used to vibrate the slurry to ensure the density and integrity of the concrete. After the concrete pouring is completed, a comprehensive inspection is carried out to ensure that there are no cracks or other quality problems in the poured parts. If cracks occur, the concrete must be re-spatched and repaired for a second time. After the concrete solidifies, it should be watered and cured immediately to ensure sufficient moisture and temperature. The curing time is not less than 7 days.

10. The in-situ cast-in-place construction process for the prestressed arched slab roof of a large-span granary according to claim 1 is characterized by: The prestressed tendons in S5 are released by sand box relaxation method, jack relaxation method, tension relaxation method and oxygen cutting method; and the connecting steel bars of the cast-in-place prestressed pedestal or the prefabricated prestressed pedestal are cut by a cutting machine or oxygen cutting method, the cast-in-place prestressed pedestal or the prefabricated prestressed pedestal is disassembled, and then the formwork is disassembled and removed, and finally the lower surface of the arch roof is filled and repaired with concrete.

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