CN112554560A - Post-tensioning method prestress construction method for flat slab structure - Google Patents
Post-tensioning method prestress construction method for flat slab structure Download PDFInfo
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- CN112554560A CN112554560A CN202011270092.7A CN202011270092A CN112554560A CN 112554560 A CN112554560 A CN 112554560A CN 202011270092 A CN202011270092 A CN 202011270092A CN 112554560 A CN112554560 A CN 112554560A
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- 238000010276 construction Methods 0.000 title claims abstract description 44
- 238000000034 method Methods 0.000 title claims abstract description 44
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 77
- 239000010959 steel Substances 0.000 claims abstract description 77
- 238000013461 design Methods 0.000 claims abstract description 45
- 238000007789 sealing Methods 0.000 claims abstract description 32
- 239000011148 porous material Substances 0.000 claims abstract description 25
- 239000000463 material Substances 0.000 claims abstract description 20
- 230000000149 penetrating effect Effects 0.000 claims abstract description 13
- 230000002787 reinforcement Effects 0.000 claims abstract description 7
- 238000012360 testing method Methods 0.000 claims abstract description 7
- 238000009434 installation Methods 0.000 claims abstract description 4
- 210000002435 tendon Anatomy 0.000 claims description 61
- 239000004568 cement Substances 0.000 claims description 27
- 239000002002 slurry Substances 0.000 claims description 27
- 238000007689 inspection Methods 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 238000004873 anchoring Methods 0.000 claims description 15
- 230000008569 process Effects 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 238000005520 cutting process Methods 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- 239000002390 adhesive tape Substances 0.000 claims description 6
- 239000010410 layer Substances 0.000 claims description 6
- 239000003973 paint Substances 0.000 claims description 6
- 239000011241 protective layer Substances 0.000 claims description 6
- 229910001018 Cast iron Inorganic materials 0.000 claims description 3
- 239000011398 Portland cement Substances 0.000 claims description 3
- 239000000654 additive Substances 0.000 claims description 3
- 230000000740 bleeding effect Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 3
- 230000005611 electricity Effects 0.000 claims description 3
- 238000004049 embossing Methods 0.000 claims description 3
- 238000011010 flushing procedure Methods 0.000 claims description 3
- 238000011900 installation process Methods 0.000 claims description 3
- 238000010297 mechanical methods and process Methods 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 238000012797 qualification Methods 0.000 claims description 3
- 238000003908 quality control method Methods 0.000 claims description 3
- 238000003860 storage Methods 0.000 claims description 3
- 238000012546 transfer Methods 0.000 claims description 3
- 239000002023 wood Substances 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 3
- 238000009432 framing Methods 0.000 abstract description 2
- 238000013102 re-test Methods 0.000 abstract 1
- 238000009435 building construction Methods 0.000 description 2
- 239000011440 grout Substances 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000004078 waterproofing Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B5/00—Floors; Floor construction with regard to insulation; Connections specially adapted therefor
- E04B5/16—Load-carrying floor structures wholly or partly cast or similarly formed in situ
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Abstract
The invention provides a post-tensioning method prestressed construction method of a flat slab structure, which comprises the steps of prestressed material entering, re-testing → reinforcement cage binding, cushion block in place → prestressed steel strand penetrating → hidden acceptance, cross-over testing, concrete pouring → anchor installation and tensioning equipment → tensioning, locking → pore channel grouting → anchor sealing → project acceptance. According to the post-tensioning prestress construction method for the flat slab structure, the lattice column bearing support is used as a temporary support, a stress system is clear, and compared with a traditional full framing scaffold, a large amount of materials and labor are saved; the prestressed flat slab structure fully meets the design appearance modeling and quality requirements after being molded; the formed prestressed flat slab has smooth surface, easy guarantee of concrete compactness and good surface impression effect.
Description
Technical Field
The invention relates to the field of building construction methods, in particular to a post-tensioning method prestress construction method for a flat slab structure.
Background
Concrete cooperation reinforcing bar at its top of in-process of current building construction pours and forms, but the unable at utmost of utilization height space between the floor of current structure, it is inconvenient to use, current reinforcing bar in case can't adjust the use after the building is accomplished in addition, cause working error, thereby cause the reduction of quality, it is inconvenient to use, need use a large amount of scaffolds to cooperate the construction when traditional building uses, traditional full hall scaffold wastes a large amount of materials and manual work, current concrete is at the in-process unevenness of pouring, concrete compactness is difficult to guarantee, the surface impression is poor.
Disclosure of Invention
The invention aims to provide a post-tensioning method prestressed construction method of a flat slab structure, aiming at overcoming the defects in the prior art, and solving the problems in the background art.
In order to achieve the purpose, the invention is realized by the following technical scheme: a post-tensioning method prestress construction method for a flat slab structure is characterized in that: the construction method comprises the following steps:
the method comprises the following steps: the prestressed material enters a field and is subjected to rechecking; carrying out template construction according to a design drawing and a lofting sheet; the construction acceptance of the sample plate is qualified, personnel and materials are ready, and the materials are blanked according to a lofting sheet; after the pre-embedding construction of the template, the steel bar and the water and electricity is finished, the acceptance is qualified, and the construction is started after the procedure transfer procedure is handled;
step two: binding a steel bar framework and a cushion block in place; during blanking, the steel strands are numbered one by one according to the principle of firstly arranging long ribs and then arranging short ribs, and the steel strands are numbered uniformly and have the same length; controlling the blanking length: the steel strand is ensured to be straight and not to be overlapped with other steel strands in the paying-off process; the steel wire can penetrate into the steel pipe for blanking; bundling and binding according to the number, binding one wire by each 2m, and buckling a wire binding head into the bundle; when the heights are not uniform, the cushion blocks are used for cushioning, so that the heights are consistent;
step three: penetrating a prestressed steel strand; firstly, manufacturing a prestressed tendon, cutting 4-6 steel strands with the length of 1m in the manufacturing process of the prestressed tendon, carrying out pressure test, and carrying out formal embossing after the pattern is determined to be qualified; the pattern is like a bulb type, and the steel wires are scattered and bent without rib breakage and are qualified;
step four: penetrating a corrugated pipe; the prestressed steel strand pipe is manually penetrated and bundled firstly; the bundling mode is as follows: firstly, threading and then tubing, namely, putting the prestressed tendons into the steel reinforcement framework, and then sleeving the spiral pipe and the connector section by section; collecting the whole bundle of the bundle; during the bundle penetrating construction, workers stand on the scaffold, and penetrate the prestressed tendons into the pore channels one by one; wrapping the front end of the bundle into a bullet shape by using adhesive tapes, manufacturing a traction head for a long (L is more than 60m) curved bundle, and pulling forwards and pushing backwards; measures should be taken after the prestressed tendons penetrate, so that rainwater is prevented from being corroded, and electric damage and mechanical damage are prevented;
step five: concealed acceptance inspection, handover inspection and concrete pouring; inspecting the installation concealment of the prestressed steel strands, and pouring concrete after the inspection is qualified;
step six: mounting an anchorage device and a tensioning device; when the anchorage device is installed, the anchorage device is inspected, equipment is calibrated and pre-inspected; installing a tensioning device at one side of an anchorage device, designing the proportion of grouting material and anchor sealing concrete before tensioning, and checking the quality of member concrete;
step seven: tensioning and locking; the tensioning sequence is according to the design requirement or construction scheme, and the tensioning is performed according to floors, parts and sections; all floors and parts follow the principle of symmetry and uniformity, and equipment is moved as little as possible; adopting graded tensioning and graded anchoring, batch tensioning, stage tensioning and compensation tensioning; the tension anchoring procedure adopts: 0 → 10% σ con → 103% σ con → anchor; measuring the elongation of the prestressed tendon during tensioning: the measuring method can measure the extension of the cylinder body of the jack or the length change of the exposed prestressed tendon; and (3) comparing the actually measured prestressed tendon elongation with the calculated elongation value: if the error is within +/-6 percent, the stretching is normally suspended, the reason is found out, and the stretching can be continued after measures are taken; filling in a prestress tension record;
step eight: grouting a pore passage; before pore grouting, concrete needs to be made into cement blocks, the quality of the concrete is checked, and the specific steps of the pore grouting are as follows: after the prestressed tendons are tensioned and anchored, slurry is timely poured and the plugging work of an anchorage device is well done; the grouting cement is preferably ordinary Portland cement with the grade of not less than 32.5, the water cement ratio is not more than 0.4, and additives for improving the performance of the cement paste can be properly added; the grouting equipment comprises a stirrer, a grouting pump, a slurry storage barrel, a filter, a rubber tube, a connector, a control valve and the like; checking whether the grouting hole and the exhaust hole are communicated with the prestressed tendon pore passage or not, and if not, carrying out pretreatment; preparing grouting material and feeding in sequence: water → admixture (stirring) → cement (stirring); the lower layer and the upper layer are sequentially grouted; each prestressed pipeline is suitable for continuous grouting, and each pore channel needs to be continuously filled with grouting once; if the water cannot be filled continuously at one time, the water is used for flushing, and then the water is poured again; checking the slurry outlet and the exhaust hole one by one from the near to the far of the grouting hole, and sealing one by one after the discharged thick slurry overflows; after the thick slurry overflows from the last slurry outlet hole, sealing the slurry outlet hole, continuously pressurizing (0.4-0.6 Mpa), maintaining the pressure for 2min, and sealing the grouting hole; a group of cubic test pieces with the side length of 70.7mm are kept in each work shift; filling a grouting record;
step nine: sealing the anchorage device; after grouting is finished and the strength meets the design requirement, cutting the steel strand and plugging the anchor head; sealing the anchor according to the design requirement; when no specific requirements are required in design, the design is in accordance with the specifications and related regulations, the anchor sealing concrete is preferably sealed by fine aggregate concrete with the strength higher by one grade than the design strength of the member, and the hidden acceptance inspection is carried out;
step ten: checking and accepting the project; in the prestress construction process, inspection and acceptance of inspection lots are required to be done, and finally, project inspection and acceptance are applied.
In a preferred mode of the present invention, the corrugated pipe is a flat galvanized corrugated pipe, and the length of the corrugated pipe joint is 200mm to 300 mm.
As a preferred mode of the present invention, the grout holes and the vent holes inside the step four and the step eight may be commonly used with each other.
As a preferred mode of the invention, the vertical deviation of the prestressed tendon position in the prestressed tendon installation process in the third step is 10mm, the horizontal deviation is 30mm, and the vertical deviation of the anchor backing plate and the end axis of the prestressed tendon is 10 mm; the beam-shaped beam-direction position deviation qualified rate is more than 92%, and the deviation of more than 15mm is not required; the qualification rate in the horizontal direction is more than 80 percent; when the anchorage device in the step six is installed, the anchorage device adopts a cast iron finished anchorage device matched with the sleeve; the anchorage device finishes the bundle penetrating of the prestressed steel strands, is installed in a tensioning section, is in plug-in connection with the sleeve, and the joint position is sealed by an adhesive tape; a foamed wood plate processing template is adopted between the anchorage device and the template for reinforcement and sealing treatment; the anchorage device is fixed on the steel bar framework and the beam slab template.
As a preferred mode of the invention, in the seventh step, when the tension is used, the tension process should ensure that the stress of each prestressed tendon in the same bundle is uniform; when the prestressed steel strands are tensioned one by one or one by one, the condition that the stress state unfavorable to the structure does not occur in each stage is ensured, and when a stress control tensioning method is adopted, the elongation value of the prestressed tendon is checked; the relative allowable deviation of the actual elongation values from the design calculated theoretical elongation values is ± 6%. The prestressed tendons should be prevented from breaking or slipping during the tensioning process. When the steel wire is broken or slipped, the number of the broken or slipped steel wire is strictly more than 3 percent of the total number of the prestressed tendons with the same section, each steel wire bundle is not more than one steel wire, and the internal shrinkage of the prestressed tendons at the tensioning end in the anchoring stage meets the design requirement; when no specific requirement exists in design, the heading screw anchor is 1mm, the top pressure of the conical anchor and the clamping piece type anchor is not more than 5mm, and the top pressure of the conical anchor and the clamping piece type anchor is 6 mm-8 mm.
As a preferred mode of the invention, the grouting quality control in the step eight is to perform pore grouting as early as possible after the prestressed tendons are tensioned, and cement slurry in the pores is full and compact; the water cement ratio of the cement paste for grouting is not more than 0.4, and the bleeding rate after 3 hours of stirring is not more than 3%. Grouting is carried out according to the design requirement by using the cement paste strength; if no specific requirements are required in design, the slurry strength is not lower than the standard value of the cubic compressive strength of the concrete of the member.
As a preferable mode of the invention, the anchor sealing in the ninth step is implemented by taking effective measures for preventing the anchor from corroding and suffering from mechanical damage; the thickness of the protective layer of the anchor at the convex anchoring end is not less than 50 mm; exposed prestressed tendon protective layer thickness: when the device is in a normal environment, the thickness of the device is not less than 20 mm; when the paint is in an environment which is easy to corrode, the thickness of the paint is not less than 50 mm; cutting the exposed part of the steel strand after anchoring by a mechanical method, wherein the exposed length of the steel strand is not more than 1.5 times of the diameter of the steel strand and is not more than 30 mm; the strength of the anchor sealing concrete is required to be carried out according to the design requirement; when the design has no specific requirements, the fine aggregate concrete with the strength higher than the designed strength of the member by one grade is preferably adopted for plugging.
The invention has the beneficial effects that:
1. according to the post-tensioning prestress construction method for the flat slab structure, the lattice column bearing support is used as a temporary support, a stress system is clear, and compared with a traditional full framing scaffold, a large amount of materials and labor are saved; the prestressed flat slab structure fully meets the design appearance modeling and quality requirements after being molded; the formed prestressed flat slab has smooth surface, easy guarantee of concrete compactness and good surface impression effect.
2. The invention relates to a post-tensioning method prestress construction method of a flat slab structure, wherein the materials of prestressed pipes, prestressed tendons, grouting pipes, exhaust holes and prestressed steel strands of the prestressed flat slab structure are selected, arranged and installed according to a design drawing strictly; the method comprises the steps of prestress tensioning method of the prestress flat slab, tensioning locking value, anchor selection, anchor sealing and waterproofing, grouting mode, grouting pressure measurement, selection and implementation, and ensures the working quality.
3. The post-tensioning prestressed construction method for the flat slab structure reduces concrete cracks, reduces the deflection of concrete members, improves the working quality, ensures the production quality, is convenient to use, has multiple functions, and meets the requirements under different conditions.
Drawings
FIG. 1 is a flow chart of a post-tensioning pre-stressing construction method for a flat slab structure according to the present invention;
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.
Referring to fig. 1, the present invention provides a technical solution: a post-tensioning method prestress construction method for a flat slab structure is characterized in that: the construction method comprises the following steps:
the method comprises the following steps: the prestressed material enters a field and is subjected to rechecking; carrying out template construction according to a design drawing and a lofting sheet; the construction acceptance of the sample plate is qualified, personnel and materials are ready, and the materials are blanked according to a lofting sheet; after the pre-embedding construction of the template, the steel bar and the water and electricity is finished, the acceptance is qualified, and the construction is started after the procedure transfer procedure is handled;
step two: binding a steel bar framework and a cushion block in place; during blanking, the steel strands are numbered one by one according to the principle of firstly arranging long ribs and then arranging short ribs, and the steel strands are numbered uniformly and have the same length; controlling the blanking length: the steel strand is ensured to be straight and not to be overlapped with other steel strands in the paying-off process; the steel wire can penetrate into the steel pipe for blanking; bundling and binding according to the number, binding one wire by each 2m, and buckling a wire binding head into the bundle; when the heights are not uniform, the cushion blocks are used for cushioning, so that the heights are consistent;
step three: penetrating a prestressed steel strand; firstly, manufacturing a prestressed tendon, cutting 4-6 steel strands with the length of 1m in the manufacturing process of the prestressed tendon, carrying out pressure test, and carrying out formal embossing after the pattern is determined to be qualified; the pattern is like a bulb type, and the steel wires are scattered and bent without rib breakage and are qualified;
step four: penetrating a corrugated pipe; the prestressed steel strand pipe is manually penetrated and bundled firstly; the bundling mode is as follows: firstly, threading and then tubing, namely, putting the prestressed tendons into the steel reinforcement framework, and then sleeving the spiral pipe and the connector section by section; collecting the whole bundle of the bundle; during the bundle penetrating construction, workers stand on the scaffold, and penetrate the prestressed tendons into the pore channels one by one; wrapping the front end of the bundle into a bullet shape by using adhesive tapes, manufacturing a traction head for a long (L is more than 60m) curved bundle, and pulling forwards and pushing backwards; measures should be taken after the prestressed tendons penetrate, so that rainwater is prevented from being corroded, and electric damage and mechanical damage are prevented;
step five: concealed acceptance inspection, handover inspection and concrete pouring; inspecting the installation concealment of the prestressed steel strands, and pouring concrete after the inspection is qualified;
step six: mounting an anchorage device and a tensioning device; when the anchorage device is installed, the anchorage device is inspected, equipment is calibrated and pre-inspected; installing a tensioning device at one side of an anchorage device, designing the proportion of grouting material and anchor sealing concrete before tensioning, and checking the quality of member concrete;
step seven: tensioning and locking; the tensioning sequence is according to the design requirement or construction scheme, and the tensioning is performed according to floors, parts and sections; all floors and parts follow the principle of symmetry and uniformity, and equipment is moved as little as possible; adopting graded tensioning and graded anchoring, batch tensioning, stage tensioning and compensation tensioning; the tension anchoring procedure adopts: 0 → 10% σ con → 103% σ con → anchor; measuring the elongation of the prestressed tendon during tensioning: the measuring method can measure the extension of the cylinder body of the jack or the length change of the exposed prestressed tendon; and (3) comparing the actually measured prestressed tendon elongation with the calculated elongation value: if the error is within +/-6 percent, the stretching is normally suspended, the reason is found out, and the stretching can be continued after measures are taken; filling in a prestress tension record;
step eight: grouting a pore passage; before pore grouting, concrete needs to be made into cement blocks, the quality of the concrete is checked, and the specific steps of the pore grouting are as follows: after the prestressed tendons are tensioned and anchored, slurry is timely poured and the plugging work of an anchorage device is well done; the grouting cement is preferably ordinary Portland cement with the grade of not less than 32.5, the water cement ratio is not more than 0.4, and additives for improving the performance of the cement paste can be properly added; the grouting equipment comprises a stirrer, a grouting pump, a slurry storage barrel, a filter, a rubber tube, a connector, a control valve and the like; checking whether the grouting hole and the exhaust hole are communicated with the prestressed tendon pore passage or not, and if not, carrying out pretreatment; preparing grouting material and feeding in sequence: water → admixture (stirring) → cement (stirring); the lower layer and the upper layer are sequentially grouted; each prestressed pipeline is suitable for continuous grouting, and each pore channel needs to be continuously filled with grouting once; if the water cannot be filled continuously at one time, the water is used for flushing, and then the water is poured again; checking the slurry outlet and the exhaust hole one by one from the near to the far of the grouting hole, and sealing one by one after the discharged thick slurry overflows; after the thick slurry overflows from the last slurry outlet hole, sealing the slurry outlet hole, continuously pressurizing (0.4-0.6 Mpa), maintaining the pressure for 2min, and sealing the grouting hole; a group of cubic test pieces with the side length of 70.7mm are kept in each work shift; filling a grouting record;
step nine: sealing the anchorage device; after grouting is finished and the strength meets the design requirement, cutting the steel strand and plugging the anchor head; sealing the anchor according to the design requirement; when no specific requirements are required in design, the design is in accordance with the specifications and related regulations, the anchor sealing concrete is preferably sealed by fine aggregate concrete with the strength higher by one grade than the design strength of the member, and the hidden acceptance inspection is carried out;
step ten: checking and accepting the project; in the prestress construction process, inspection and acceptance of inspection lots are required to be done, and finally, project inspection and acceptance are applied.
In a preferred mode of the present invention, the corrugated pipe is a flat galvanized corrugated pipe, and the length of the corrugated pipe joint is 200mm to 300 mm.
As a preferred mode of the present invention, the grout holes and the vent holes inside the step four and the step eight may be commonly used with each other.
As a preferred mode of the invention, the vertical deviation of the prestressed tendon position in the prestressed tendon installation process in the third step is 10mm, the horizontal deviation is 30mm, and the vertical deviation of the anchor backing plate and the end axis of the prestressed tendon is 10 mm; the beam-shaped beam-direction position deviation qualified rate is more than 92%, and the deviation of more than 15mm is not required; the qualification rate in the horizontal direction is more than 80 percent; when the anchorage device in the step six is installed, the anchorage device adopts a cast iron finished anchorage device matched with the sleeve; the anchorage device finishes the bundle penetrating of the prestressed steel strands, is installed in a tensioning section, is in plug-in connection with the sleeve, and the joint position is sealed by an adhesive tape; a foamed wood plate processing template is adopted between the anchorage device and the template for reinforcement and sealing treatment; the anchorage device is fixed on the steel bar framework and the beam slab template.
As a preferred mode of the invention, in the seventh step, when the tension is used, the tension process should ensure that the stress of each prestressed tendon in the same bundle is uniform; when the prestressed steel strands are tensioned one by one or one by one, the condition that the stress state unfavorable to the structure does not occur in each stage is ensured, and when a stress control tensioning method is adopted, the elongation value of the prestressed tendon is checked; the relative allowable deviation of the actual elongation values from the design calculated theoretical elongation values is ± 6%. The prestressed tendons should be prevented from breaking or slipping during the tensioning process. When the steel wire is broken or slipped, the number of the broken or slipped steel wire is strictly more than 3 percent of the total number of the prestressed tendons with the same section, each steel wire bundle is not more than one steel wire, and the internal shrinkage of the prestressed tendons at the tensioning end in the anchoring stage meets the design requirement; when no specific requirement exists in design, the heading screw anchor is 1mm, the top pressure of the conical anchor and the clamping piece type anchor is not more than 5mm, and the top pressure of the conical anchor and the clamping piece type anchor is 6 mm-8 mm.
As a preferred mode of the invention, the grouting quality control in the step eight is to perform pore grouting as early as possible after the prestressed tendons are tensioned, and cement slurry in the pores is full and compact; the water cement ratio of the cement paste for grouting is not more than 0.4, and the bleeding rate after 3 hours of stirring is not more than 3%. Grouting is carried out according to the design requirement by using the cement paste strength; if no specific requirements are required in design, the slurry strength is not lower than the standard value of the cubic compressive strength of the concrete of the member.
As a preferable mode of the invention, the anchor sealing in the ninth step is implemented by taking effective measures for preventing the anchor from corroding and suffering from mechanical damage; the thickness of the protective layer of the anchor at the convex anchoring end is not less than 50 mm; exposed prestressed tendon protective layer thickness: when the device is in a normal environment, the thickness of the device is not less than 20 mm; when the paint is in an environment which is easy to corrode, the thickness of the paint is not less than 50 mm; cutting the exposed part of the steel strand after anchoring by a mechanical method, wherein the exposed length of the steel strand is not more than 1.5 times of the diameter of the steel strand and is not more than 30 mm; the strength of the anchor sealing concrete is required to be carried out according to the design requirement; when the design has no specific requirements, the fine aggregate concrete with the strength higher than the designed strength of the member by one grade is preferably adopted for plugging.
While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (7)
1. A post-tensioning method prestress construction method for a flat slab structure is characterized in that: the construction method comprises the following steps:
the method comprises the following steps: the prestressed material enters a field and is subjected to rechecking; carrying out template construction according to a design drawing and a lofting sheet; the construction acceptance of the sample plate is qualified, personnel and materials are ready, and the materials are blanked according to a lofting sheet; after the pre-embedding construction of the template, the steel bar and the water and electricity is finished, the acceptance is qualified, and the construction is started after the procedure transfer procedure is handled;
step two: binding a steel bar framework and a cushion block in place; during blanking, the steel strands are numbered one by one according to the principle of firstly arranging long ribs and then arranging short ribs, and the steel strands are numbered uniformly and have the same length; controlling the blanking length: the steel strand is ensured to be straight and not to be overlapped with other steel strands in the paying-off process; the steel wire can penetrate into the steel pipe for blanking; bundling and binding according to the number, binding one wire by each 2m, and buckling a wire binding head into the bundle; when the heights are not uniform, the cushion blocks are used for cushioning, so that the heights are consistent;
step three: penetrating a prestressed steel strand; firstly, manufacturing a prestressed tendon, cutting 4-6 steel strands with the length of 1m in the manufacturing process of the prestressed tendon, carrying out pressure test, and carrying out formal embossing after the pattern is determined to be qualified; the pattern is like a bulb type, and the steel wires are scattered and bent without rib breakage and are qualified;
step four: penetrating a corrugated pipe; the prestressed steel strand pipe is manually penetrated and bundled firstly; the bundling mode is as follows: firstly, threading and then tubing, namely, putting the prestressed tendons into the steel reinforcement framework, and then sleeving the spiral pipe and the connector section by section; collecting the whole bundle of the bundle; during the bundle penetrating construction, workers stand on the scaffold, and penetrate the prestressed tendons into the pore channels one by one; wrapping the front end of the bundle into a bullet shape by using adhesive tapes, manufacturing a traction head for a long (L is more than 60m) curved bundle, and pulling forwards and pushing backwards; measures should be taken after the prestressed tendons penetrate, so that rainwater is prevented from being corroded, and electric damage and mechanical damage are prevented;
step five: concealed acceptance inspection, handover inspection and concrete pouring; inspecting the installation concealment of the prestressed steel strands, and pouring concrete after the inspection is qualified;
step six: mounting an anchorage device and a tensioning device; when the anchorage device is installed, the anchorage device is inspected, equipment is calibrated and pre-inspected; installing a tensioning device at one side of an anchorage device, designing the proportion of grouting material and anchor sealing concrete before tensioning, and checking the quality of member concrete;
step seven: tensioning and locking; the tensioning sequence is according to the design requirement or construction scheme, and the tensioning is performed according to floors, parts and sections; all floors and parts follow the principle of symmetry and uniformity, and equipment is moved as little as possible; adopting graded tensioning and graded anchoring, batch tensioning, stage tensioning and compensation tensioning; the tension anchoring procedure adopts: 0 → 10% σ con → 103% σ con → anchor; measuring the elongation of the prestressed tendon during tensioning: the measuring method can measure the extension of the cylinder body of the jack or the length change of the exposed prestressed tendon; and (3) comparing the actually measured prestressed tendon elongation with the calculated elongation value: if the error is within +/-6 percent, the stretching is normally suspended, the reason is found out, and the stretching can be continued after measures are taken; filling in a prestress tension record;
step eight: grouting a pore passage; before pore grouting, concrete needs to be made into cement blocks, the quality of the concrete is checked, and the specific steps of the pore grouting are as follows: after the prestressed tendons are tensioned and anchored, slurry is timely poured and the plugging work of an anchorage device is well done; the grouting cement is preferably ordinary Portland cement with the grade of not less than 32.5, the water cement ratio is not more than 0.4, and additives for improving the performance of the cement paste can be properly added; the slurry equipment comprises a stirrer, a grouting pump, a slurry storage barrel, a filter, a rubber tube, a connector, a control valve and the like; checking whether the grouting hole and the exhaust hole are communicated with the prestressed tendon pore passage or not, and if not, carrying out pretreatment; preparing grouting material and feeding in sequence: water → admixture (stirring) → cement (stirring); the lower layer and the upper layer are sequentially grouted; each prestressed pipeline is suitable for continuous grouting, and each pore channel needs to be continuously filled with grouting once; if the water cannot be filled continuously at one time, the water is used for flushing, and then the water is poured again; checking the slurry outlet and the exhaust hole one by one from the near to the far of the grouting hole, and sealing one by one after the discharged thick slurry overflows; after the thick slurry overflows from the last slurry outlet hole, sealing the slurry outlet hole, continuously pressurizing (0.4-0.6 Mpa), maintaining the pressure for 2min, and sealing the grouting hole; a group of cubic test pieces with the side length of 70.7mm are kept in each work shift; filling a grouting record;
step nine: sealing the anchorage device; after grouting is finished and the strength meets the design requirement, cutting the steel strand and plugging the anchor head; sealing the anchor according to the design requirement; when no specific requirements are required in design, the design is in accordance with the specifications and related regulations, the anchor sealing concrete is preferably sealed by fine aggregate concrete with the strength higher by one grade than the design strength of the member, and the hidden acceptance inspection is carried out;
step ten: checking and accepting the project; in the prestress construction process, inspection and acceptance of inspection lots are required to be done, and finally, project inspection and acceptance are applied.
2. The post-tensioning prestressed construction method of a flat slab structure according to claim 1, characterized in that: the corrugated pipe is a flat galvanized corrugated pipe, and the length of a corrugated pipe joint is 200mm-300 mm.
3. The post-tensioning prestressed construction method of a flat slab structure according to claim 1, characterized in that: and grouting holes and exhaust holes in the fourth step and the eighth step can be mutually universal.
4. The post-tensioning prestressed construction method of a flat slab structure according to claim 1, characterized in that: the vertical deviation of the prestressed tendon position in the prestressed tendon installation process in the third step is 10mm, the horizontal deviation is 30mm, and the vertical deviation of the anchor backing plate and the axis of the tail end of the prestressed tendon is 10 mm; the beam-shaped beam-direction position deviation qualified rate is more than 92%, and the deviation of more than 15mm is not required; the qualification rate in the horizontal direction is more than 80 percent; when the anchorage device in the step six is installed, the anchorage device adopts a cast iron finished anchorage device matched with the sleeve; the anchorage device finishes the bundle penetrating of the prestressed steel strands, is installed in a tensioning section, is in plug-in connection with the sleeve, and the joint position is sealed by an adhesive tape; a foamed wood plate processing template is adopted between the anchorage device and the template for reinforcement and sealing treatment; the anchorage device is fixed on the steel bar framework and the beam slab template.
5. The post-tensioning prestressed construction method of a flat slab structure according to claim 1, characterized in that: when the step seven is used for tensioning, the tensioning process can ensure that the stress of each prestressed tendon in the same bundle is uniform; when the prestressed steel strands are tensioned one by one or one by one, the condition that the stress state unfavorable to the structure does not occur in each stage is ensured, and when a stress control tensioning method is adopted, the elongation value of the prestressed tendon is checked; the relative allowable deviation of the actual elongation values from the design calculated theoretical elongation values is ± 6%. The prestressed tendons should be prevented from breaking or slipping during the tensioning process. When the steel wire is broken or slipped, the number of the broken or slipped steel wire is strictly more than 3 percent of the total number of the prestressed tendons with the same section, each steel wire bundle is not more than one steel wire, and the internal shrinkage of the prestressed tendons at the tensioning end in the anchoring stage meets the design requirement; when no specific requirement exists in design, the heading screw anchor is 1mm, the top pressure of the conical anchor and the clamping piece type anchor is not more than 5mm, and the top pressure of the conical anchor and the clamping piece type anchor is 6 mm-8 mm.
6. The post-tensioning prestressed construction method of a flat slab structure according to claim 1, characterized in that: the grouting quality control of the step eight is to perform pore grouting as early as possible after the prestressed tendons are tensioned, and cement paste in the pores is full and compact; the water cement ratio of the cement paste for grouting is not more than 0.4, and the bleeding rate after 3 hours of stirring is not more than 3%. Grouting is carried out according to the design requirement by using the cement paste strength; if no specific requirements are required in design, the slurry strength is not lower than the standard value of the cubic compressive strength of the concrete of the member.
7. The post-tensioning prestressed construction method of a flat slab structure according to claim 1, characterized in that: in the step nine, effective measures for preventing the anchorage device from being corroded and damaged by machinery are taken during anchorage sealing; the thickness of the protective layer of the anchor at the convex anchoring end is not less than 50 mm; exposed prestressed tendon protective layer thickness: when the device is in a normal environment, the thickness of the device is not less than 20 mm; when the paint is in an environment which is easy to corrode, the thickness of the paint is not less than 50 mm; cutting the exposed part of the steel strand after anchoring by a mechanical method, wherein the exposed length of the steel strand is not more than 1.5 times of the diameter of the steel strand and is not more than 30 mm; the strength of the anchor sealing concrete is required to be carried out according to the design requirement; when the design has no specific requirements, the fine aggregate concrete with the strength higher than the designed strength of the member by one grade is preferably adopted for plugging.
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