CN113524429A - Pre-tensioning method precast slab beam construction process - Google Patents
Pre-tensioning method precast slab beam construction process Download PDFInfo
- Publication number
- CN113524429A CN113524429A CN202110625727.9A CN202110625727A CN113524429A CN 113524429 A CN113524429 A CN 113524429A CN 202110625727 A CN202110625727 A CN 202110625727A CN 113524429 A CN113524429 A CN 113524429A
- Authority
- CN
- China
- Prior art keywords
- concrete
- tensioning
- cement
- prestressed
- core mold
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
- B28B23/02—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
- B28B23/04—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed
- B28B23/043—Wire anchoring or tensioning means for the reinforcements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/04—Producing shaped prefabricated articles from the material by tamping or ramming
- B28B1/045—Producing shaped prefabricated articles from the material by tamping or ramming combined with vibrating or jolting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/08—Producing shaped prefabricated articles from the material by vibrating or jolting
- B28B1/093—Producing shaped prefabricated articles from the material by vibrating or jolting by means directly acting on the material, e.g. by cores wholly or partly immersed in the material or elements acting on the upper surface of the material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
- B28B11/24—Apparatus or processes for treating or working the shaped or preshaped articles for curing, setting or hardening
- B28B11/245—Curing concrete articles
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Structural Engineering (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention belongs to the technical field of municipal engineering equipment, in particular to a construction process of a pre-tensioning method precast slab beam, which comprises the following steps of (a) adopting portland cement and ordinary portland cement as raw materials, and adopting cement produced by a cement plant in the same engineering so as to keep the appearance color of a member consistent; the batch-by-batch re-examination of the incoming bulk cement should be carried out in 500 tons. According to the construction process of the pre-tensioning method precast slab beam, the anti-cracking degree and the rigidity of the member are improved by arranging the construction process of the pre-tensioning method precast slab beam; the material can be saved, and the dead weight can be reduced; the vertical shearing force and the main tensile stress of the concrete can be reduced; the structure quality is safe and reliable; the prestress can be used as a means for connecting structural members, and the development of a new system and a construction method of a bridge structure is promoted; the pre-tensioning construction process is simple, the disk bundle is self-anchored by the adhesive force, a specially-made anchorage device is not needed to be consumed, and the anchorage device used for temporary fixation can be repeatedly used.
Description
Technical Field
The invention relates to the technical field of municipal engineering equipment, in particular to a construction process of a pre-tensioning precast slab beam.
Background
Municipal works refer to municipal infrastructure construction works. In China, municipal infrastructure refers to various buildings, structures, equipment and the like which are arranged in planning and construction ranges of urban areas and towns (villages) and provide paid or unpaid public products and services for residents based on government responsibilities and obligations. Various public infrastructure construction supporting in urban life all belong to municipal works category, for example common urban road, bridge, subway, underground pipeline, tunnel, river course, track traffic, sewage treatment, refuse treatment processing etc. engineering, for example again with the life closely relevant various pipelines: rainwater, sewage, water supply, reclaimed water, electric power (parts except red lines), telecommunication, heating power, gas and the like, and construction of squares, urban greening and the like belong to the municipal engineering category.
When a bridge is built on a highway, one bridge is in a beam type. The bridge span structure is a 25m long pre-tensioned prestressed hollow slab beam, and 128 pieces in total are prefabricated on site. The plate beam has a section different from that of a common prestressed T-shaped beam, has the advantages of large torsional moment of inertia, good stability of a single piece and the like, and is often used as an economic and reasonable structural form to be widely selected in bridge engineering. However, the construction method has certain defects, such as high technical requirement, certain construction difficulty and large self weight of the components, so that a pre-tensioning method precast slab beam construction process is required.
Disclosure of Invention
Based on the technical problem of the existing bridge construction, the invention provides a pre-tensioning method precast slab beam construction process.
The invention provides a construction process of a pre-tensioning method precast slab beam, which comprises the following steps of firstly, adopting raw materials, namely a Portland cement and a common Portland cement, and adopting cement produced by a cement plant in the same project to keep the appearance color of a member consistent; the batch-by-batch re-inspection of the bulk cement entering the factory is carried out according to 500 tons, the qualified bulk cement can be used for producing the plate girder, and a quality certificate of a manufacturer is required to be attached; b. the coarse aggregate is hard macadam with nominal particle size of 5-25 mm or 5-31.5, the stone powder content is less than or equal to 1.0% by weight, and the void ratio is less than 47%; c. the fine aggregate is medium sand with reasonable selection gradation, hard texture and clean particles, and the fineness modulus of the medium sand is controlled to be between 2.3 and 3.0; d. reinforcing steel bars; e. steel strand wires; f. an additive; g. the release agent adopts machine oil; h. an anchorage device;
secondly, manufacturing a pre-tensioned prestressed main reinforcement, namely adopting a high-strength prestressed concrete steel strand and the blanking length of the prestressed steel strand, and calculating and determining according to the used data of an anchorage device, the working rod degree, a connector, the elongation, the tensioning elongation, the length of a pedestal, the length of a member and the spacing distance of the member;
step three, manufacturing and binding non-prestressed reinforcements, namely using phi 6 and phi 8 reinforcements on the prestressed plate girder, using the straightened reinforcements after a disc-round reinforcement straightening process, wherein the cross-sectional area of the straightened reinforcements cannot be reduced by 5%, and the cross-sectional area of a welding joint of the reinforcements cannot exceed 25% of the total cross-sectional area of the stressed reinforcements no matter the stressed or tensioned area when flash contact butt welding is adopted for the butt welding of the butt welding joints of the reinforcements within a controlled range;
applying pre-tensioning prestress to ensure that the concrete plate beam member obtains necessary prestress, and correctly tensioning the prestressed tendons (steel strands) to ensure that the loss value of the prestress does not exceed an allowable value; 0 → 20% σ k → 100% σ k (hold load for 5 minutes and anchor);
selecting the concrete mixing proportion, namely curing a concrete sample with the concrete grade of (150 multiplied by 150) mm in air with the temperature of 20 +/-2 ℃ and the relative humidity of not less than 95 percent for 28 days to obtain the ultimate compressive strength (N/mm) obtained by pressure test2) Converting the non-standard-size test piece;
step six, stirring concrete, wherein cement, water and an additive are added, and the Xuxu deviation is 1% by weight; coarse and fine aggregates-with an allowable deviation of 2% by weight; special materials for sand and stone for plate beams; the cement is silicate cement; when the concrete is stirred in the stirrer, the continuous stirring time is not less than 90 seconds from the time when all materials are put into the stirring cylinder to the time when the concrete starts to be discharged from the cylinder;
seventhly, transporting the concrete by adopting a concrete hopper; the temperature of 20-30 ℃ is not easy to exceed 10 minutes; the temperature of 2.10-19 ℃ is not easy to exceed 15 minutes; the temperature of 3.5-9 ℃ is not easy to exceed 20 minutes;
step eight, inflating and installing the capsule core mold, wherein the plate beam is a hollow plate, and the inflatable capsule core mold is adopted for supporting the mold;
step nine, concrete is tamped, and when the concrete is tamped by adopting an insertion type tamping tool, the insertion distance of the concrete is 40 cm; the concrete should be vibrated until the concrete stops sinking, no obvious bubbles rise, the surface is flat and consistent, and thin-layer cement paste is presented;
step ten, concrete curing; the maintenance of the plate girder is mainly natural maintenance, and anti-freezing and heat-preserving measures are taken when the outdoor temperature is lower than 2 ℃; after the concrete is poured into the capsule, the capsule is immediately covered by flannelette, and a specially assigned person is sent to carry out frequent watering maintenance; maintaining for more than 3 days and nights; watering every day for keeping the surface of the concrete in a wet state; the quality condition of the curing water is the same as that of the concrete mixing water;
step eleven, drawing the capsule core mold, performing the whole rubber tube after air bleeding, and drawing by using a 1-ton winch and a steering roller to be arranged at the end part of the steel template; the drawing speed should be slowly carried out, and the people should be sent to command; after the core mold is completely drawn out, cement paste attached to the surface of the core mold is carefully removed, tap water is used for washing the core mold, whether the core mold is damaged or not and air leakage is detected, and if the core mold is air leakage is found, the core mold is repaired in time;
step twelve, firstly stretching the prestressed main reinforcements, and when the prestressed reinforcements are released, adopting 5000KN jacks at the stretching ends of the pedestals, and performing group jacking (the tonnage of the jacking tension is not more than 1.05 times of the tonnage of the tensioning tension) so as to loosen the screw caps; after the prestressed tendons are relaxed in groups, cutting off the prestressed tendons by gas cutting; when cutting off the prestressed tendons, cutting off the prestressed tendons from the release end of the pedestal to the other end in a successive tangential manner and symmetrically from the outside to the center; the outflow elongation of the main reinforcement is based on 2 cm of the notch, and the reinforcement cannot be exposed out of the half-section panel; when the reinforcing steel bars are cut off by gas cutting, a waste steel plate is laid below a gas cutting point so as to prevent the concrete bottom plate of the pedestal from being damaged;
step thirteen, the quality standard, the finished plate beam products should be inspected and accepted piece by piece, and the used materials, accessories and the quality inspection of each procedure in the production process all meet each relevant technical requirement; if the quality does not meet the standard, the product is corrected or processed in time and cannot be allowed to flow into the next procedure;
fourteen, hoisting, stacking, leaving factory and transporting the components, wherein the components are large in size, heavy in weight and long in length, so that difficulty is brought to hoisting, two gantry crane hoisting processes are adopted for hoisting the components, and a specially-assigned person is required to be responsible for commanding;
fifthly, taking technical safety measures, wherein obvious warning signs are arranged around the tensioning site, and are blocked by ropes, so that personnel irrelevant to work are strictly prohibited from entering a dangerous area; both ends of the beam should be provided with perfect safety protection measures; when in tensioning, people are prohibited from standing behind the jack, so that the prestressed tendons are prevented from being pulled apart or the anchorage device is prevented from slipping out to hurt people.
Preferably, the step four is a specific step in tensioning: a. after the prestressed tendons are laid, straightening the prestressed main tendons at the tensioning end of the pedestal by using a 5000KN jack, and then tensioning each prestressed tendon to the range of 20 percent sigma k one by one at the other end of the pedestal by using a 250KN stretcher to ensure that each prestressed tendon is stressed uniformly; b. and after the first-step tensioning work is finished, binding the steel bars of the beam body, tensioning the steel bars to 100 percent sigma k at the tensioning end of the pedestal by adopting a 5000KN jack group after the binding of the steel bars is finished, holding the load for 5 minutes, and anchoring by using a special screw.
Preferably, the fifth step prevents the concrete from having too high hydration heat and too large shrinkage, the cement dosage cannot be increased arbitrarily, and the maximum dosage of the C40-C50 concrete is not more than 500 kg/cubic meter; controlling the slump constant to be 50-70mm when the concrete is poured; the admixture is prepared to reduce the participation of solution so as to ensure uniform stirring; the laboratory must list the actual dosage of the additive in the grading list produced each time according to the change of the sandstone and the content; the members of the mixing station must prepare the aqueous solution strictly in the amount of gradation and prepare for weighing.
Preferably, in the sixth step, before the mixer and the first tank of concrete are used for each time, the mixer is started to run empty, after the running is normal, clear water is added to run idle for 2-3 minutes, so that the whole barrel of the mixer is wetted, and then water accumulated in the barrel is drained and then the materials are loaded; when the first mixed concrete is mixed, 10% more cement, water and fine aggregate are added according to the mixing proportion, so that the mortar is fully distributed on the inner wall of the cylinder and the stirring blades, and the mortar loss of the first mixed concrete mixture is prevented.
Preferably, when the capsule core die system used by the slab beam member in the step eight is in a special specification (two tubes or three tubes are sleeved with outer sleeves), the two tubes or three tubes are all arranged in the outer sleeves, then the inflation is carried out, the inflation pressure is 0.35-0.42 MP, and a pressure gauge is required to be additionally arranged at the end of the capsule for detection and control; maintaining the capsule core mold, and cleaning concrete residues on the surface of the capsule core mold after the capsule core mold is inflated to ensure the smoothness of the surface of the capsule core mold; after the core is molded into the reinforcement cage, the position is accurate, the core is fixed by positioning reinforcement hoops, the spacing between the positioning reinforcement hoops is 100cm, and the core is required to be firmly tied according to the reinforcing steel bar single-injection side; in the process of pouring concrete, whether the capsule tube has air leakage or not is carefully checked, the air pressure of the capsule is checked every 30 minutes from the beginning of pouring concrete to the time when the capsule is deflated, and the air is inflated in time when air leakage is found, so that the inflation pressure in the tube is kept stable.
Preferably, the step eleven capsule core mold deflation time is determined by reference to the following table values:
when the temperature is 0-5 ℃, the concrete is required to be poured for 10-20 hours;
when the temperature is 5-15 ℃, the concrete is required to be poured for 8-10 hours;
when the temperature is 15-20 ℃, the concrete is required to be poured for 6-8 hours;
when the temperature is 20-30 ℃, the concrete is required to be poured for 4-6 hours;
when the temperature is higher than 30 ℃, the concrete is required to be poured.
Preferably, the following quality checks should be performed during the concrete construction process of step thirteen: a. inspecting the quality and specification of concrete composition materials, and when the specification of the sandstone materials is not met, performing grading adjustment: the water content of the sandstone is checked once every day before the start of work; if the condition of rain or dry weather occurs, the concentration of the stirring water and the additive water solution is checked and reasonably adjusted at any time; in addition, whether the variety and the grade of the cement are required to be consistent, whether the effective time is overlong and whether the cement is hardened or deteriorated or not should be checked; b. checking the slump of the concrete at a mixing place at least once per shift; if the mixing ratio is changed or adjusted, the inspection should be carried out at any time; c. checking whether the ingredients, the water-cement ratio and the admixture mixing amount are correct or not and whether the weighing equipment is sensitive and reliable or not; d. checking whether the transportation, pouring and maintenance methods of the concrete meet the requirements; e. checking the stability of the template and the bracket structure; f. the difference between the actual elongation value of the prestress tension and the design elongation is within 6 percent.
Preferably, when the component is stacked in the fourteenth step, the supporting point is arranged outside the position of the lifting point, so that the component is in a stress structure state of the simply supported beam; the piling yard needs to be flat and firm, square piles are suitable to be used as supporting blocks at the supporting points, and two hard wood blocks are respectively padded at the two ends of the beam bottom; the transportation of the components is carried by a professional transportation vehicle, the load is 40 tons, the vehicle length (including the components) is 25 meters, and the actual terrain of the site is surveyed by a transportation team leader one day before the transportation and loading so as to ensure the smoothness of the transportation route of the beam transporting vehicle; obvious warning signs must be hung around the girder transporting vehicle, and the girder transporting vehicle must travel to a project site according to a set transportation route.
Preferably, during the fifteen-step tensioning, a specially-assigned person is responsible for commanding; when the device is operated, the main rib is strictly prevented from being touched, and the jack is stopped to be started when the elongation is measured; the prestressed anchor clamp has enough clamping capacity, so that the prestressed anchor clamp is prevented from slipping out due to infirm anchor clamp, and the damaged anchor clamp must be scrapped immediately.
The beneficial effects of the invention are as follows:
the anti-cracking degree and the rigidity of the member are improved by arranging the construction process of the pre-tensioning method precast slab beam; the material can be saved, and the dead weight can be reduced; the vertical shearing force and the main tensile stress of the concrete can be reduced; the structure quality is safe and reliable; the prestress can be used as a means for connecting structural members, and the development of a new system and a construction method of a bridge structure is promoted; the pre-tensioning construction process is simple, the disk bundle is self-anchored by the adhesive force, a specially-made anchorage device is not needed to be consumed, and the anchorage device used for temporary fixation can be repeatedly used.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.
A pre-tensioning method precast slab beam construction process, step one, raw materials, a, adopt portland cement, ordinary portland cement, the cement that the same project adopted a cement factory to produce, in order to keep the appearance color of the component unanimous; the batch-by-batch re-inspection of the bulk cement entering the factory is carried out according to 500 tons, the qualified bulk cement can be used for producing the plate girder, and a quality certificate of a manufacturer is required to be attached; b. the coarse aggregate is hard macadam with nominal particle size of 5-25 mm or 5-31.5, the stone powder content is less than or equal to 1.0% by weight, and the void ratio is less than 47%; c. the fine aggregate is medium sand with reasonable selection gradation, hard texture and clean particles, and the fineness modulus of the medium sand is controlled to be between 2.3 and 3.0; d. reinforcing steel bars; e. steel strand wires; f. an additive; g. the release agent adopts machine oil; h. an anchorage device;
secondly, manufacturing a pre-tensioned prestressed main reinforcement, namely adopting a high-strength prestressed concrete steel strand and the blanking length of the prestressed steel strand, and calculating and determining according to the used data of an anchorage device, the working rod degree, a connector, the elongation, the tensioning elongation, the length of a pedestal, the length of a member and the spacing distance of the member;
step three, manufacturing and binding non-prestressed reinforcements, namely using phi 6 and phi 8 reinforcements on the prestressed plate girder, using the straightened reinforcements after a disc-round reinforcement straightening process, wherein the cross-sectional area of the straightened reinforcements cannot be reduced by 5%, and the cross-sectional area of a welding joint of the reinforcements cannot exceed 25% of the total cross-sectional area of the stressed reinforcements no matter the stressed or tensioned area when flash contact butt welding is adopted for the butt welding of the butt welding joints of the reinforcements within a controlled range;
applying pre-tensioning prestress to ensure that the concrete plate beam member obtains necessary prestress, and correctly tensioning the prestressed tendon steel strand to ensure that the loss value of the prestress does not exceed an allowable value; 0 → 20% σ k → 100% σ k, holding the load for 5 minutes and anchoring;
step four, specific steps in tensioning: a. after the prestressed tendons are laid, straightening the prestressed main tendons at the tensioning end of the pedestal by using a 5000KN jack, and then tensioning each prestressed tendon to the range of 20 percent sigma k one by one at the other end of the pedestal by using a 250KN stretcher to ensure that each prestressed tendon is stressed uniformly; b. after the first step of tensioning work is finished, binding reinforcing steel bars of the beam body, tensioning the beam body to 100 percent sigma k at the tensioning end of the pedestal by adopting a 5000KN jack group after the reinforcing steel bars are bound, holding the load for 5 minutes, and anchoring by using a special screw;
selecting the mixing proportion of concrete, wherein the concrete sample with the concrete label of 150 multiplied by 150mm is subjected to maintenance in the air with the temperature of 20 +/-2 ℃ and the relative humidity of not less than 95 percent for 28 days to obtain the ultimate compressive strength of a pressure test, and the sample with non-standard size is converted;
fifthly, preventing the hydration heat of the concrete from being too high and the shrinkage from being too large, and the using amount of the cement cannot be increased arbitrarily, wherein the maximum using amount of the C40-C50 concrete is not more than 500 kg/cubic meter; controlling the slump constant to be 50-70mm when the concrete is poured; the admixture is prepared to reduce the participation of solution so as to ensure uniform stirring; the laboratory must list the actual dosage of the additive in the grading list produced each time according to the change of the sandstone and the content; the members of the stirring staff must strictly prepare the aqueous solution according to the grading amount and prepare for weighing;
step six, stirring concrete, wherein cement, water and an additive are added, and the Xuxu deviation is 1% by weight; coarse and fine aggregates-with an allowable deviation of 2% by weight; special materials for sand and stone for plate beams; the cement is silicate cement; when the concrete is stirred in the stirrer, the continuous stirring time is not less than 90 seconds from the time when all materials are put into the stirring cylinder to the time when the concrete starts to be discharged from the cylinder;
sixthly, before the mixer and the first tank of concrete are used each time, the mixer is started to run empty, after the running is normal, clear water is added to run idle for 2-3 minutes, so that the whole mixer barrel is wetted, and then water accumulated in the barrel is drained and then the materials are loaded; when the first mixed concrete is mixed, 10 percent more cement, water and fine aggregate are added according to the mixing proportion, so that the mortar is fully distributed on the inner wall of the cylinder and the stirring blades, and the mortar loss of the first mixed concrete mixture is prevented;
seventhly, transporting the concrete by adopting a concrete hopper; the temperature of 20-30 ℃ is not easy to exceed 10 minutes; the temperature of 2.10-19 ℃ is not easy to exceed 15 minutes; the temperature of 3.5-9 ℃ is not easy to exceed 20 minutes;
step eight, inflating and installing the capsule core mold, wherein the plate beam is a hollow plate, and the inflatable capsule core mold is adopted for supporting the mold; when two or three tubes are sleeved with sleeves for use, the two or three tubes are all arranged in the sleeves, then the air is inflated, the inflation pressure is 0.35-0.42 MP, and a pressure gauge is required to be additionally arranged at the capsule end for detection and control; maintaining the capsule core mold, and cleaning concrete residues on the surface of the capsule core mold after the capsule core mold is inflated to ensure the smoothness of the surface of the capsule core mold; after the core is molded into the reinforcement cage, the position is accurate, the core is fixed by positioning reinforcement hoops, the spacing between the positioning reinforcement hoops is 100cm, and the core is required to be firmly tied according to the reinforcing steel bar single-injection side; in the process of pouring concrete, whether the capsule tube has an air leakage phenomenon or not is carefully checked, the air pressure of the capsule is checked every 30 minutes from the beginning of pouring concrete to the time of releasing air of the capsule, and when air leakage is found, the air is inflated in time to keep the inflation pressure in the tube stable;
step nine, concrete is tamped, and when the concrete is tamped by adopting an insertion type tamping tool, the insertion distance of the concrete is 40 cm; the concrete should be vibrated until the concrete stops sinking, no obvious bubbles rise, the surface is flat and consistent, and thin-layer cement paste is presented;
step ten, concrete curing; the maintenance of the plate girder is mainly natural maintenance, and anti-freezing and heat-preserving measures are taken when the outdoor temperature is lower than 2 ℃; after the concrete is poured into the capsule, the capsule is immediately covered by flannelette, and a specially assigned person is sent to carry out frequent watering maintenance; maintaining for more than 3 days and nights; watering every day for keeping the surface of the concrete in a wet state; the quality condition of the curing water is the same as that of the concrete mixing water;
step eleven, drawing the capsule core mold, performing the whole rubber tube after air bleeding, and drawing by using a 1-ton winch and a steering roller to be arranged at the end part of the steel template; the drawing speed should be slowly carried out, and the people should be sent to command; after the core mold is completely drawn out, cement paste attached to the surface of the core mold is carefully removed, tap water is used for washing the core mold, whether the core mold is damaged or not and air leakage is detected, and if the core mold is air leakage is found, the core mold is repaired in time;
step eleven the capsule core mold deflation time, referring to the following numerical values:
when the temperature is 0-5 ℃, the concrete is required to be poured for 10-20 hours;
when the temperature is 5-15 ℃, the concrete is required to be poured for 8-10 hours;
when the temperature is 15-20 ℃, the concrete is required to be poured for 6-8 hours;
when the temperature is 20-30 ℃, the concrete is required to be poured for 4-6 hours;
when the temperature is higher than 30 ℃, the concrete is required to be poured completely;
step twelve, firstly stretching the prestressed main reinforcements, and when the prestressed reinforcements are released, adopting 5000KN jacks at the stretching ends of the pedestals for group top stretching, wherein the tonnage of the top stretching does not exceed 1.05 times of the tonnage of the stretching so as to loosen the screw cap; after the prestressed tendons are relaxed in groups, cutting off the prestressed tendons by gas cutting; when cutting off the prestressed tendons, cutting off the prestressed tendons from the release end of the pedestal to the other end in a successive tangential manner and symmetrically from the outside to the center; the outflow elongation of the main reinforcement is based on 2 cm of the notch, and the reinforcement cannot be exposed out of the half-section panel; when the reinforcing steel bars are cut off by gas cutting, a waste steel plate is laid below a gas cutting point so as to prevent the concrete bottom plate of the pedestal from being damaged;
step thirteen, the quality standard, the finished plate beam products should be inspected and accepted piece by piece, and the used materials, accessories and the quality inspection of each procedure in the production process all meet each relevant technical requirement; if the quality does not meet the standard, the product is corrected or processed in time and cannot be allowed to flow into the next procedure;
thirteen concrete construction processes are carried out with the following quality inspection: a. inspecting the quality and specification of concrete composition materials, and when the specification of the sandstone materials is not met, performing grading adjustment: the water content of the sandstone is checked once every day before the start of work; if the condition of rain or dry weather occurs, the concentration of the stirring water and the additive water solution is checked and reasonably adjusted at any time; in addition, whether the variety and the grade of the cement are required to be consistent, whether the effective time is overlong and whether the cement is hardened or deteriorated or not should be checked; b. checking the slump of the concrete at a mixing place at least once per shift; if the mixing ratio is changed or adjusted, the inspection should be carried out at any time; c. checking whether the ingredients, the water-cement ratio and the admixture mixing amount are correct or not and whether the weighing equipment is sensitive and reliable or not; d. checking whether the transportation, pouring and maintenance methods of the concrete meet the requirements; e. checking the stability of the template and the bracket structure; f. the difference between the actual elongation value of the prestress tension and the design elongation is within 6 percent;
fourteen, hoisting, stacking, leaving factory and transporting the components, wherein the components are large in size, heavy in weight and long in length, so that difficulty is brought to hoisting, two gantry crane hoisting processes are adopted for hoisting the components, and a specially-assigned person is required to be responsible for commanding;
when the components are stacked, the supporting points are arranged outside the positions of the hanging points, so that the components are in a stress structure state of the simply supported beams; the piling yard needs to be flat and firm, square piles are suitable to be used as supporting blocks at the supporting points, and two hard wood blocks are respectively padded at the two ends of the beam bottom; the transportation of the components is carried by a professional transportation vehicle, the load is 40 tons, the length of the vehicle contains 25 meters of the components, and the actual terrain of the site is surveyed by a transportation team leader one day before the transportation and loading so as to ensure the smoothness of the transportation route of the girder transportation vehicle; obvious warning signs must be hung around the girder transporting vehicle, and the girder transporting vehicle must travel to an engineering site according to a set transportation route;
fifthly, taking technical safety measures, wherein obvious warning signs are arranged around the tensioning site, and are blocked by ropes, so that personnel irrelevant to work are strictly prohibited from entering a dangerous area; both ends of the beam should be provided with perfect safety protection measures; during tensioning, people are strictly prohibited from standing behind the jack so as to prevent the prestressed tendons from being pulled off or the anchorage device from slipping out to hurt people;
fifteen during tensioning, a specially-assigned person is responsible for commanding; when the device is operated, the main rib is strictly prevented from being touched, and the jack is stopped to be started when the elongation is measured; the prestressed anchor clamp has enough clamping capacity, prevents the anchor clamp from slipping out due to infirm, and must be immediately scrapped for the damaged anchor clamp;
the anti-cracking degree and the rigidity of the member are improved by arranging the construction process of the pre-tensioning method precast slab beam; the material can be saved, and the dead weight can be reduced; the vertical shearing force and the main tensile stress of the concrete can be reduced; the structure quality is safe and reliable; the prestress can be used as a means for connecting structural members, and the development of a new system and a construction method of a bridge structure is promoted; the pre-tensioning construction process is simple, the disk bundle is self-anchored by the adhesive force, a specially-made anchorage device is not needed to be consumed, and the anchorage device used for temporary fixation can be repeatedly used.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (9)
1. A pre-tensioning method precast slab beam construction process is characterized in that: step one, raw materials, a, adopting portland cement and ordinary portland cement, and adopting cement produced by a cement plant in the same project to keep the appearance color of the member consistent; the batch-by-batch re-inspection of the bulk cement entering the factory is carried out according to 500 tons, the qualified bulk cement can be used for producing the plate girder, and a quality certificate of a manufacturer is required to be attached; b. the coarse aggregate is hard macadam with nominal particle size of 5-25 mm or 5-31.5, the stone powder content is less than or equal to 1.0% by weight, and the void ratio is less than 47%; c. the fine aggregate is medium sand with reasonable selection gradation, hard texture and clean particles, and the fineness modulus of the medium sand is controlled to be between 2.3 and 3.0; d. reinforcing steel bars; e. steel strand wires; f. an additive; g. the release agent adopts machine oil; h. an anchorage device;
secondly, manufacturing a pre-tensioned prestressed main reinforcement, namely adopting a high-strength prestressed concrete steel strand and the blanking length of the prestressed steel strand, and calculating and determining according to the used data of an anchorage device, the working rod degree, a connector, the elongation, the tensioning elongation, the length of a pedestal, the length of a member and the spacing distance of the member;
step three, manufacturing and binding non-prestressed reinforcements, namely using phi 6 and phi 8 reinforcements on the prestressed plate girder, using the straightened reinforcements after a disc-round reinforcement straightening process, wherein the cross-sectional area of the straightened reinforcements cannot be reduced by 5%, and the cross-sectional area of a welding joint of the reinforcements cannot exceed 25% of the total cross-sectional area of the stressed reinforcements no matter the stressed or tensioned area when flash contact butt welding is adopted for the butt welding of the butt welding joints of the reinforcements within a controlled range;
applying pre-tensioning prestress to ensure that the concrete plate beam member obtains necessary prestress, and correctly tensioning the prestressed tendons (steel strands) to ensure that the loss value of the prestress does not exceed an allowable value; 0 → 20% σ k → 100% σ k (hold load for 5 minutes and anchor);
selecting the concrete mixing proportion, namely curing a concrete sample with the concrete grade of (150 multiplied by 150) mm in air with the temperature of 20 +/-2 ℃ and the relative humidity of not less than 95 percent for 28 days to obtain the ultimate compressive strength (N/mm) obtained by pressure test2) Converting the non-standard-size test piece;
step six, stirring concrete, wherein cement, water and an additive are added, and the Xuxu deviation is 1% by weight; coarse and fine aggregates-with an allowable deviation of 2% by weight; special materials for sand and stone for plate beams; the cement is silicate cement; when the concrete is stirred in the stirrer, the continuous stirring time is not less than 90 seconds from the time when all materials are put into the stirring cylinder to the time when the concrete starts to be discharged from the cylinder;
seventhly, transporting the concrete by adopting a concrete hopper; the temperature of 20-30 ℃ is not easy to exceed 10 minutes; the temperature of 2.10-19 ℃ is not easy to exceed 15 minutes; the temperature of 3.5-9 ℃ is not easy to exceed 20 minutes;
step eight, inflating and installing the capsule core mold, wherein the plate beam is a hollow plate, and the inflatable capsule core mold is adopted for supporting the mold;
step nine, concrete is tamped, and when the concrete is tamped by adopting an insertion type tamping tool, the insertion distance of the concrete is 40 cm; the concrete should be vibrated until the concrete stops sinking, no obvious bubbles rise, the surface is flat and consistent, and thin-layer cement paste is presented;
step ten, concrete curing; the maintenance of the plate girder is mainly natural maintenance, and anti-freezing and heat-preserving measures are taken when the outdoor temperature is lower than 2 ℃; after the concrete is poured into the capsule, the capsule is immediately covered by flannelette, and a specially assigned person is sent to carry out frequent watering maintenance; maintaining for more than 3 days and nights; watering every day for keeping the surface of the concrete in a wet state; the quality condition of the curing water is the same as that of the concrete mixing water;
step eleven, drawing the capsule core mold, performing the whole rubber tube after air bleeding, and drawing by using a 1-ton winch and a steering roller to be arranged at the end part of the steel template; the drawing speed should be slowly carried out, and the people should be sent to command; after the core mold is completely drawn out, cement paste attached to the surface of the core mold is carefully removed, tap water is used for washing the core mold, whether the core mold is damaged or not and air leakage is detected, and if the core mold is air leakage is found, the core mold is repaired in time;
step twelve, firstly stretching the prestressed main reinforcements, and when the prestressed reinforcements are released, adopting 5000KN jacks at the stretching ends of the pedestals, and performing group jacking (the tonnage of the jacking tension is not more than 1.05 times of the tonnage of the tensioning tension) so as to loosen the screw caps; after the prestressed tendons are relaxed in groups, cutting off the prestressed tendons by gas cutting; when cutting off the prestressed tendons, cutting off the prestressed tendons from the release end of the pedestal to the other end in a successive tangential manner and symmetrically from the outside to the center; the outflow elongation of the main reinforcement is based on 2 cm of the notch, and the reinforcement cannot be exposed out of the half-section panel; when the reinforcing steel bars are cut off by gas cutting, a waste steel plate is laid below a gas cutting point so as to prevent the concrete bottom plate of the pedestal from being damaged;
step thirteen, the quality standard, the finished plate beam products should be inspected and accepted piece by piece, and the used materials, accessories and the quality inspection of each procedure in the production process all meet each relevant technical requirement; if the quality does not meet the standard, the product is corrected or processed in time and cannot be allowed to flow into the next procedure;
fourteen, hoisting, stacking, leaving factory and transporting the components, wherein the components are large in size, heavy in weight and long in length, so that difficulty is brought to hoisting, two gantry crane hoisting processes are adopted for hoisting the components, and a specially-assigned person is required to be responsible for commanding;
fifthly, taking technical safety measures, wherein obvious warning signs are arranged around the tensioning site, and are blocked by ropes, so that personnel irrelevant to work are strictly prohibited from entering a dangerous area; both ends of the beam should be provided with perfect safety protection measures; when in tensioning, people are prohibited from standing behind the jack, so that the prestressed tendons are prevented from being pulled apart or the anchorage device is prevented from slipping out to hurt people.
2. The pre-tensioning precast slab beam construction process according to claim 1, wherein: the fourth step is the specific step during tensioning: a. after the prestressed tendons are laid, straightening the prestressed main tendons at the tensioning end of the pedestal by using a 5000KN jack, and then tensioning each prestressed tendon to the range of 20 percent sigma k one by one at the other end of the pedestal by using a 250KN stretcher to ensure that each prestressed tendon is stressed uniformly; b. and after the first-step tensioning work is finished, binding the steel bars of the beam body, tensioning the steel bars to 100 percent sigma k at the tensioning end of the pedestal by adopting a 5000KN jack group after the binding of the steel bars is finished, holding the load for 5 minutes, and anchoring by using a special screw.
3. The pre-tensioning precast slab beam construction process according to claim 1, wherein: fifthly, the excessive high hydration heat and excessive shrinkage of the concrete are prevented, the cement dosage cannot be increased at will, and the maximum dosage of the C40-C50 concrete is not more than 500 kg/cubic meter; controlling the slump constant to be 50-70mm when the concrete is poured; the admixture is prepared to reduce the participation of solution so as to ensure uniform stirring; the laboratory must list the actual dosage of the additive in the grading list produced each time according to the change of the sandstone and the content; the members of the mixing station must prepare the aqueous solution strictly in the amount of gradation and prepare for weighing.
4. The pre-tensioning precast slab beam construction process according to claim 1, wherein: in the sixth step, before the mixer and the first tank of concrete are used each time, the mixer is started to run empty, after the running is normal, clear water is added to run idle for 2-3 minutes, so that the whole barrel of the mixer is wetted, and then the water accumulated in the barrel is drained and then the materials are loaded; when the first mixed concrete is mixed, 10% more cement, water and fine aggregate are added according to the mixing proportion, so that the mortar is fully distributed on the inner wall of the cylinder and the stirring blades, and the mortar loss of the first mixed concrete mixture is prevented.
5. The pre-tensioning precast slab beam construction process according to claim 1, wherein: when the capsule core mould system used by the plate beam component in the step eight is in a special specification (two pipes or three pipes are sleeved with sleeves), the two pipes or three pipes are all arranged in the sleeves, then the air inflation is carried out, the air inflation pressure is 0.35-0.42 MP, and a pressure gauge is required to be additionally arranged at the capsule end for detection and control; maintaining the capsule core mold, and cleaning concrete residues on the surface of the capsule core mold after the capsule core mold is inflated to ensure the smoothness of the surface of the capsule core mold; after the core is molded into the reinforcement cage, the position is accurate, the core is fixed by positioning reinforcement hoops, the spacing between the positioning reinforcement hoops is 100cm, and the core is required to be firmly tied according to the reinforcing steel bar single-injection side; in the process of pouring concrete, whether the capsule tube has air leakage or not is carefully checked, the air pressure of the capsule is checked every 30 minutes from the beginning of pouring concrete to the time when the capsule is deflated, and the air is inflated in time when air leakage is found, so that the inflation pressure in the tube is kept stable.
6. The pre-tensioning precast slab beam construction process according to claim 1, wherein: the step eleven comprises the capsule core mold deflation time according to the following numerical values:
when the temperature is 0-5 ℃, the concrete is required to be poured for 10-20 hours;
when the temperature is 5-15 ℃, the concrete is required to be poured for 8-10 hours;
when the temperature is 15-20 ℃, the concrete is required to be poured for 6-8 hours;
when the temperature is 20-30 ℃, the concrete is required to be poured for 4-6 hours;
when the temperature is higher than 30 ℃, the concrete is required to be poured.
7. The pre-tensioning precast slab beam construction process according to claim 1, wherein: the thirteen concrete steps should be carried out with the following quality inspection: a. inspecting the quality and specification of concrete composition materials, and when the specification of the sandstone materials is not met, performing grading adjustment: the water content of the sandstone is checked once every day before the start of work; when the water is dry in rainy days or weather, the concentration of the stirring water and the additive water solution is checked and reasonably adjusted at any time; in addition, whether the variety and the grade of the cement are required to be consistent, whether the effective time is overlong and whether the cement is hardened or deteriorated or not should be checked; b. checking the slump of the concrete at a mixing place at least once per shift; when the mix proportion is changed and adjusted, the inspection should be carried out at any time; c. checking whether the ingredients, the water-cement ratio and the admixture mixing amount are correct or not and whether the weighing equipment is sensitive and reliable or not; d. checking whether the transportation, pouring and maintenance methods of the concrete meet the requirements; e. checking the stability of the template and the bracket structure; f. the difference between the actual elongation value of the prestress tension and the design elongation is within 6 percent.
8. The pre-tensioning precast slab beam construction process according to claim 1, wherein: when the component is stacked in the step fourteen, the support point is arranged outside the position of the lifting point, so that the component is in a stress structure state of the simply supported beam; the piling yard needs to be flat and firm, square piles are suitable to be used as supporting blocks at the supporting points, and two hard wood blocks are respectively padded at the two ends of the beam bottom; the transportation of the components is carried by a professional transportation vehicle, the load is 40 tons, the vehicle length (including the components) is 25 meters, and the actual terrain of the site is surveyed by a transportation team leader one day before the transportation and loading so as to ensure the smoothness of the transportation route of the beam transporting vehicle; obvious warning signs must be hung around the girder transporting vehicle, and the girder transporting vehicle must travel to a project site according to a set transportation route.
9. The pre-tensioning precast slab beam construction process according to claim 1, wherein: during the fifteen-step tensioning, a specially-assigned person is responsible for commanding; when the device is operated, the main rib is strictly prevented from being touched, and the jack is stopped to be started when the elongation is measured; the prestressed anchor clamp has enough clamping capacity, so that the prestressed anchor clamp is prevented from slipping out due to infirm anchor clamp, and the damaged anchor clamp must be scrapped immediately.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110625727.9A CN113524429A (en) | 2021-06-04 | 2021-06-04 | Pre-tensioning method precast slab beam construction process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110625727.9A CN113524429A (en) | 2021-06-04 | 2021-06-04 | Pre-tensioning method precast slab beam construction process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113524429A true CN113524429A (en) | 2021-10-22 |
Family
ID=78095187
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110625727.9A Withdrawn CN113524429A (en) | 2021-06-04 | 2021-06-04 | Pre-tensioning method precast slab beam construction process |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113524429A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114603701A (en) * | 2022-04-13 | 2022-06-10 | 武汉市华江幸福装配式建筑有限公司 | Production and processing method of green prestressed laminated slab |
-
2021
- 2021-06-04 CN CN202110625727.9A patent/CN113524429A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114603701A (en) * | 2022-04-13 | 2022-06-10 | 武汉市华江幸福装配式建筑有限公司 | Production and processing method of green prestressed laminated slab |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111455855B (en) | Construction process of main bridge of double-tower single-cable-plane short-tower cable-stayed bridge | |
| CN106284044B (en) | A kind of novel steel-concrete combined bridge and its construction method | |
| CN111946124B (en) | Method for manufacturing silo with vertical shaft structure by using section bar combined frame for silo | |
| CN109747037A (en) | A kind of elder generation's post-tensioned prestressing combines the U-shaped beam prefabricated construction technology of large span of construction | |
| CN105926470B (en) | Elevated bridge remodeling method | |
| CN108330835A (en) | The construction method of setting bracket | |
| CN112049143B (en) | Large-sized concrete bearing platform construction method for large-sized low-temperature storage tank | |
| CN110939051A (en) | Subway hidden cover beam construction method | |
| CN109162204B (en) | Construction method for transverse block rapid assembling of bridge substructure | |
| CN114892552B (en) | Box girder type bridge reconstruction construction method | |
| CN111997066A (en) | Manufacturing and construction method of assembled prestressed anchor cable frame beam for slope reinforcement | |
| CN112211113A (en) | Cast-in-place construction method for large-span diamond-shaped bent cap of high pier | |
| CN112502041A (en) | Method for crossing karst cavity by cast-in-situ box girder in karst tunnel | |
| CN113152262A (en) | Bridge single-column pier reinforcement construction method | |
| CN112323641A (en) | Construction method of pretensioned prestressing concrete hollow simply supported beam | |
| CN113216010A (en) | Construction method for closure section of corrugated steel web bridge | |
| CN115306645A (en) | Wind power generation concrete tower barrel installation construction method | |
| CN113524429A (en) | Pre-tensioning method precast slab beam construction process | |
| CN113681676B (en) | High-temperature steam-curing construction method for UHPC steel-concrete composite beam prefabricated bridge deck without coarse aggregate | |
| CN115369778A (en) | Construction method of steel cross beam rotating body structure | |
| CN110747762A (en) | Cement member crossing highway and its installation method | |
| CN117449216A (en) | Bridge lower beam construction method | |
| CN117488692A (en) | Bridge concrete box girder construction method | |
| CN112609584A (en) | Prefabricated small box girder installation construction method for intelligent express way | |
| CN117431839A (en) | Construction method of cast-in-situ beam of pipeline bridge of south-water and north-water-crossing main channel |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20211022 |
|
| WW01 | Invention patent application withdrawn after publication |