Fold line pre-tensioning method prestressed concrete I-beam long-line prefabricating system

Abstract

The invention belongs to the technical field of bridge construction, and particularly relates to a broken line pre-tensioning method prestressed concrete I-beam long-line prefabricating system which comprises the following steps: step 1, a construction preparation stage: cleaning and leveling a prefabricating site; and 2, a tensioning system design and construction stage: designing and constructing a tensioning system according to bridge design parameters. And step 3, a bottom template polishing / release agent brushing stage: polishing the surface of the bottom template, and uniformly smearing a release agent. According to the broken line pre-tensioning method prestressed concrete I-shaped beam long-line prefabricating system, by arranging the steps from the first step to the seventeen step, in the prefabricating process of a concrete I-shaped beam, the prefabricating technology of the concrete I-shaped beam is optimized, and an automatic steel strand tensioning device is matched, so that one-time synchronous tensioning is conducted on a plurality of steel strands; and the tension of the steel strand is adjusted according to the tension monitoring data, so that the tension precision is improved, and the effects of improving the quality and the production efficiency of bridge components are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, and in particular to a long-line prefabrication system for prestressed concrete I-beams using a broken-line pretensioning method. Background Art

[0002] The fold line prestressing method is a relatively advanced prefabrication method for small and medium span prestressed concrete bridges in China, which can meet the requirements of prefabrication, assembly and rapidity of bridge design and construction in my country at this stage. In the field of bridge construction, prestressed concrete structure has become one of the important materials in bridge construction due to its excellent mechanical properties and economy. As a key component of the bridge, the prefabrication technology and quality of the I-beam directly affect the overall performance and service life of the bridge. Summary of the invention

[0003] The invention proposes a long-line prefabrication system for prestressed concrete I-beams using a broken-line pretensioning method, aiming to optimize the I-beam prefabrication process and improve the quality and production efficiency of bridge components.

[0004] The present invention proposes a long-line prefabrication system for prestressed concrete I-beams using a folding line pretensioning method, comprising the following steps:

[0005] Step 1: Construction preparation stage: clean and level the prefabrication site.

[0006] Step 2: Tensioning system design and construction phase: Design and construct the tensioning system based on the bridge design parameters.

[0007] Step 3: Bottom template grinding / brushing release agent stage: Grind the surface of the bottom template and evenly apply the release agent.

[0008] Step 4: Install the bottom template: Install the processed bottom template accurately.

[0009] Step 5: Install the prestressed tendons / connectors: Arrange the prestressed tendons according to the design drawings and connect the connectors.

[0010] Step 6: Steel cage processing / hoisting stage: Process the steel cage according to the design requirements and hoist it to the correct position.

[0011] Step 7: End template grinding / mold release agent application stage: Grind the end template and apply mold release agent.

[0012] Step 8: Install the end template: Fix the polished end template in place.

[0013] Step 9. Tensioning equipment inspection / calibration phase: Conduct a comprehensive inspection and calibration of the tensioning equipment.

[0014] Step 10, prestressed tendon tensioning stage: prestressed tendon steel strands are tensioned according to specifications. The steel strands are tensioned using an automatic steel strand tensioning device to tension all steel strands simultaneously. During the tensioning process, the tension of the steel strands is monitored, and the tension of a single steel strand is adjusted based on the monitoring data.

[0015] Step 11: Side template grinding / brushing release agent stage: Grind the side template and apply release agent.

[0016] Step 12: Install the side formwork: Install the polished side formwork in place.

[0017] Step 13: Concrete pouring / vibration stage: Pour the concrete evenly and vibrate it to make it dense using a vibrating rod or a flat vibrator.

[0018] Step 14: Test block preparation stage: Prepare concrete test blocks according to standards to test their performance.

[0019] Step 15. Concrete curing stage: ensure that the concrete is fully cured under specified conditions.

[0020] Step 16, prestressed tendon release stage: After the concrete reaches the design strength, gradually release the tension of the prestressed tendons.

[0021] Step 17: Lifting to the beam storage area: Safely lift the prefabricated I-beam to the designated storage area.

[0022] Preferably, the construction preparation stage also includes prefabrication site construction, technical preparation, site preparation, measurement preparation and test preparation.

[0023] The prefabrication yard is constructed according to the prefabricated beam yard design drawing to carry out the construction of the prefabricated pedestal, the processing of the steel bar binding frame, and the processing of the prefabricated beam formwork.

[0024] Preferably, during the steel cage processing / hanging stage, the steel bars are processed into semi-finished products in the steel bar processing workshop, transported to the steel bar binding cradle area of ​​the precast beam yard, and respectively bound into bottom web and top plate components, and the prestressed steel strands are installed while the precast beam bottom web steel bar skeleton is being processed.

[0025] The steel cage processing / hanging stage also includes steel bar storage, steel bar cutting and bending, and steel bar installation.

[0026] Preferably, in the concrete curing stage of step fifteen, the concrete is spray-cured. After the concrete has finally set, the exposed surface is covered with geotextile and watered by an automatic sprinkler system. The automatic sprinkler system is arranged on both sides and the top surface of the precast beam. The curing time meets the requirements of the specifications, and the time interval of the spraying is sufficient to keep the concrete surface in a moist state at all times.

[0027] Preferably, the automatic steel strand tensioning device comprises a fixed base, a control box and a multi-axis robot are fixedly mounted on the upper surface of the fixed base, a PLC controller is arranged inside the control box, and the multi-axis robot is electrically connected to the PLC controller inside the control box via a cable.

[0028] The operating end of the multi-axis robot is fixedly connected with a force-applying sleeve, and the inner wall of the force-applying sleeve is fixedly connected with a plum wrench ring.

[0029] Preferably, a monitoring fixing plate is fixedly connected to the upper surface of the fixed base at one end away from the multi-axis robot, a reinforcing support frame is fixedly connected to the side surface of the monitoring fixing plate, and the lower surface of the reinforcing support frame is fixedly connected to the upper surface of the fixed base.

[0030] A plurality of through-type tension sensors are fixedly mounted on the surface of the monitoring fixed plate, and the plurality of through-type tension sensors correspond to a plurality of steel strands on the concrete I-beam.

[0031] The plurality of through-type tension sensors are electrically connected to the PLC controller inside the control box via cables.

[0032] Preferably, a guide travel groove is fixedly provided on the upper surface of the fixed base, and the two guide travel grooves are symmetrically distributed with the axis of the fixed base as the center, and the inner wall of the guide travel groove is T-shaped.

[0033] The inner wall of the guide travel groove is slidably connected with a guide moving block, the upper surfaces of the two guide moving blocks extend to the upper surface of the fixed base, the upper surface of the guide moving block is fixedly connected with a tensioning plate, and the lower surface of the tensioning plate is slidably connected to the upper surface of the fixed base.

[0034] The surface of the monitoring fixed plate and the surface of the tensioning plate are both in an I-shape, and a force hydraulic cylinder is fixedly installed on the other side surface of the monitoring fixed plate. Multiple force hydraulic cylinders are evenly distributed on the surface of the monitoring fixed plate, and the force hydraulic cylinder is electrically connected to the PLC controller inside the control box through a solenoid valve.

[0035] The force-applying hydraulic cylinder comprises a force-applying hydraulic rod, one end of which is fixedly connected to the surface of the tensioning plate.

[0036] Preferably, a plurality of tensioning holes corresponding to the plurality of through-type tension sensors are provided on the surface of the tensioning plate, a tensioning adjustment tube is slidably connected to the inner wall of the tensioning hole, one end of the tensioning adjustment tube is fixedly connected to a conical locking tube, and a plurality of locking avoidance grooves fixedly connected to the inner wall of the conical locking tube are provided on the surface of the conical locking tube.

[0037] The inner wall of the tapered locking tube is provided with an annular barb tooth groove, and a plurality of the annular barb tooth grooves are evenly distributed on the inner wall of the tapered locking tube.

[0038] Preferably, a left-hand thread groove is provided on the surface of the tensioning adjustment tube close to the conical locking tube, and the tensioning adjustment tube is threadedly connected to a locking nut through the left-hand thread groove. The surface of the locking nut is fixedly connected to a locking tube, and the inner wall of the locking tube is conical in shape and adapted to the sliding connection with the surface of the conical locking tube.

[0039] Preferably, a right thread groove and a stop travel groove are respectively provided on the surface of the tensioning adjustment tube away from the conical locking tube, and a plurality of the stop travel grooves are distributed in a ring array with the axis of the tensioning adjustment tube as the center.

[0040] The inner wall of the stop stroke groove is rectangular in shape, and a stop limit strip is slidably connected to the inner wall of the stop stroke groove. The surfaces of the plurality of stop limit strips are matched with the inner wall of the stop stroke groove, and the surface of the stop limit strips is fixedly connected to the inner wall of the tensioning hole.

[0041] The surface of the tensioning adjustment tube is threadedly connected with an adjustment nut through the right thread groove, and the surface of the adjustment nut is slidably connected with the surface of the tensioning plate.

[0042] The beneficial effects of the present invention are:

[0043] 1. By setting steps 1 to 17, during the prefabrication of concrete I-beams, the prefabrication process of concrete I-beams is optimized, and in conjunction with an automatic steel strand tensioning device, multiple steel strands can be tensioned simultaneously at one time, and the tension of the steel strands can be adjusted according to the tensioning monitoring data to improve the tensioning accuracy, thereby achieving the effect of improving the quality of bridge components and production efficiency.

[0044] 2. By setting up an automatic tensioning device for steel strands, during the prefabrication of concrete I-beams, the tensioning plate is pushed to move by the force-applying hydraulic cylinder to tension multiple steel strands synchronously, and the tension data of multiple steel strands during the tensioning process are monitored by multiple through-type tension sensors and fed back to the PLC controller. Then, the multi-axis robot automatically rotates the adjustment nut to adjust the tension of the steel strands, thereby achieving the effect of automatic prestressing and adjustment of the concrete I-beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of a long-line prefabrication system for prestressed concrete I-beams using a fold-line pretensioning method proposed by the present invention;

[0046] Figure 2A plan layout diagram of a precast beam yard for a long-line precast system of prestressed concrete I-beams using a fold-line pretensioning method proposed by the present invention;

[0047] Figure 3 A cross-sectional layout diagram of a precast beam yard for a long-line precast system of prestressed concrete I-beams using a fold-line pretensioning method proposed by the present invention;

[0048] Figure 4 This is a design drawing for the installation of casing and spiral reinforcement for a long-line prefabrication system of prestressed concrete I-beams using a folding line pretensioning method proposed by the present invention;

[0049] Figure 5 A schematic diagram of the vertical bending of steel strands in a long-line prefabrication system of prestressed concrete I-beams using a fold-line pretensioning method proposed by the present invention;

[0050] Figure 6 A cross-sectional arrangement diagram of the inner end and middle steel strands of a long-line prefabrication system of a prestressed concrete I-beam using a folding line pretensioning method proposed by the present invention;

[0051] Figure 7 A three-dimensional diagram of the fixed base structure of a long-line prefabrication system of prestressed concrete I-beams using a folding line pretensioning method proposed by the present invention;

[0052] Figure 8 A long-line prefabrication system for prestressed concrete I-beams using a folding line pretensioning method is proposed by the present invention. Figure 7 A magnified view of the structure at center;

[0053] Fig. 9 A three-dimensional diagram of the structure of a reinforced support frame of a long-line prefabrication system of prestressed concrete I-beams using a fold-line pretensioning method proposed by the present invention;

[0054] Fig.10 A three-dimensional diagram of the control box structure of a long-line prefabrication system for prestressed concrete I-beams using a folding line pretensioning method proposed by the present invention;

[0055] Fig.11 A three-dimensional diagram of the multi-axis robot structure of a long-line prefabrication system for prestressed concrete I-beams using a folding line pretensioning method proposed by the present invention;

[0056] Fig.12 A long-line prefabrication system for prestressed concrete I-beams using a folding line pretensioning method is proposed by the present invention. Fig.11 A magnified view of the structure at B in the middle;

[0057] Fig.13 A three-dimensional diagram of the tensioning adjustment pipe structure of a long-line prefabrication system of prestressed concrete I-beams using a folding line pre-tensioning method proposed by the present invention;

[0058] Fig.14A three-dimensional diagram of the conical locking tube structure of a long-line prefabrication system of prestressed concrete I-beams using a fold-line pretensioning method proposed by the present invention;

[0059] Fig.15 A half-section view of a locking tube structure of a long-line prefabrication system of prestressed concrete I-beams using a fold-line pretensioning method proposed by the present invention.

[0060] In the figure: 1. Fixed base; 2. Control box; 201. PLC controller; 3. Multi-axis robot; 301. Force sleeve; 302. Wrench ring; 4. Monitoring fixed plate; 5. Strengthening support frame; 6. Through-type tension sensor; 7. Guide stroke groove; 8. Guide moving block; 9. Tensioning plate; 10. Force hydraulic cylinder; 11. Force hydraulic rod; 12. Tensioning adjustment tube; 13. Conical locking tube; 14. Locking avoidance groove; 15. Annular barb tooth groove; 16. Left thread groove; 17. Locking nut; 18. Locking tube; 19. Right thread groove; 20. Stop stroke groove; 21. Stop limit strip; 22. Adjusting nut. DETAILED DESCRIPTION

[0061] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0062] Reference Figure 1-Figure 15 , a long-line prefabrication system for prestressed concrete I-beams using a folding line pretensioning method, comprising the following steps:

[0063] Step 1: Construction preparation stage: clean and level the prefabrication site.

[0064] Furthermore, the construction preparation phase also includes prefabrication site construction, technical preparation, site preparation, measurement preparation and test preparation.

[0065] The prefabrication yard construction shall be carried out according to the prefabricated beam yard design drawings to carry out the construction of prefabricated pedestals, the processing of steel bar binding frames, and the completion of the processing of prefabricated beam formwork, etc.

[0066] In this embodiment, the beam yard is arranged as follows:

[0067] The prefabricated beam site is 234m long and 51m wide, covering an area of ​​approximately 11,934m 2 , including 6375m2 of prefabrication area 2 , Cunliang District 5559m 2 The general layout of the precast beam yard is as follows: Figure 2 and Figure 3 shown.

[0068] Furthermore, the prefabrication area of ​​the beam yard is equipped with 6 production lines (3 for side span beams and 3 for middle span beams), and each production line produces 2 I-beams simultaneously. The steel bar binding pedestal is equipped with 2 top plate steel bar binding cradles and 2 bottom web steel bar binding cradles. After the steel bars are cut and processed into semi-finished products in the steel bar processing plant, they are transported to the steel bar binding area and processed and formed using the cradles.

[0069] Each line base is 125m long, with a reaction wall at each end for prestressing. The reaction wall adopts a pile-connected cap structure, and two bored piles with a length of 4.5m and a diameter of 1.5m are set under a single cap. Anchor trolleys and beam end bogies are set between the reaction wall and the beam end. The bogies are used to turn the steel bundles in the web, and the anchor trolleys are used to anchor the prestressed steel bundles and tension rods. By tensioning the tension rods, the anchor trolleys are driven to move, so that the prestressed steel bundles are stretched to achieve the tensioning effect.

[0070] There are 29 beam storage pedestals in the beam storage area. In addition to one pedestal for finished beams awaiting inspection, the beam storage area can store 56 beams at the same time based on the double-layer beam storage considerations.

[0071] There are two 130t gantry cranes in the yard, which are used for the transportation and hoisting of finished beams and steel frame. There is also one 28t gantry crane and one 20t gantry crane, which are used for the transportation of formwork and small machinery and equipment, and for the hoisting of hoppers during concrete pouring. The four gantry cranes are on the same track, and the top surface of the track is flush with the ground.

[0072] The water used in the field is connected to the water supply pipe of the laboratory and used for the construction of the beam field and the spraying and curing of prefabricated beams. Two horizontal drainage ditches and five longitudinal drainage ditches are set up in the prefabrication area to ensure smooth drainage in the field. The drainage ditches are constructed simultaneously with the hardening of the field.

[0073] Technical preparations include:

[0074] 1. Organize technical and production management personnel to be familiar with I-beam design drawings, project content, construction schedule, etc., and on the basis of clarifying the overall work, have a clear understanding of the construction process, quality control points, personnel, materials, external environment, etc. required for construction preparation.

[0075] 2. Make safety technical instructions for I-beam construction in advance so that the construction can proceed smoothly.

[0076] 3. Establish standardized construction management systems for safety, quality, technology, testing, etc., clarify the scope of responsibility, specific practices and guarantee measures, so that everyone is aware of it and communication channels are unobstructed.

[0077] Site preparation includes:

[0078] 1. Clean the site, store the prefabricated I-beams in the prefabrication yard, and number them to indicate the construction information (casting, etc.).

[0079] 2. The erection and commissioning of power facilities are normal; living and construction water are connected; the erection and commissioning of gantry cranes are completed; each work area is clearly classified and the access roads are unobstructed.

[0080] Measurement preparation includes:

[0081] 1. All measuring instruments should be thoroughly inspected and calibrated before construction.

[0082] 2. Review the elevations of the pedestal and the tensioning holes at the tensioning end.

[0083] Test preparation includes:

[0084] 1. Complete the inspection and declaration of raw materials.

[0085] 2. Complete the concrete mix design and declaration work.

[0086] Step 2: Tensioning system design and construction phase: Design and construct the tensioning system based on the bridge design parameters.

[0087] Step 3: Bottom template grinding / brushing release agent stage: Grind the surface of the bottom template and evenly apply the release agent.

[0088] Step 4: Install the bottom template: Install the processed bottom template accurately.

[0089] Step 5: Install the prestressed tendons / connectors: Arrange the prestressed tendons according to the design drawings and connect the connectors.

[0090] Step 6: Steel cage processing / hoisting stage: Process the steel cage according to the design requirements and hoist it to the correct position.

[0091] Furthermore, during the steel cage processing / hoisting stage, the steel bars are processed into semi-finished products in the steel bar processing workshop and transported to the steel bar binding cradle area of ​​the precast beam yard, where they are respectively bound into bottom web and top plate components. The prestressed steel strands are installed while the precast beam bottom web steel bar skeleton is being processed.

[0092] The steel cage processing / hanging stage also includes steel bar storage, steel bar cutting and bending, and steel bar installation.

[0093] Specifically, the storage of steel bars is carried out as follows: after entering the site, the steel bars are strictly classified and stacked according to different steel types, grades, brands, specifications and manufacturers, and signs are set up for easy identification. The steel bars are centrally stored in a fully enclosed steel bar processing site with a pedestal. When steel bars and semi-finished products are temporarily stored at the construction site, pedestals, sleepers and other supports of no less than 30cm in height are set up, and effective rain protection measures are taken to prevent the steel bars from rusting. It is forbidden to throw them randomly during transportation to avoid deformation of the steel bars.

[0094] Specifically, when cutting and bending steel bars, cutting and bending are carried out according to the design of the drawings, and the steel bars are classified and numbered according to the steel bar numbers in the drawings. Steel bars are cut by a grinding wheel cutter or a fully automatic hydraulic straightening and cutting machine to ensure that the ends of the steel bars are flat.

[0095] Specifically, when installing the steel bars, according to the design drawings, the diameters of the ordinary steel bars of the I-beam are φ25, φ16, φ12, and φ10 steel bars. For the welding connection extension, the double-sided weld is not less than 5d, the single-sided weld is not less than 10d, the number of steel bar joints in the same joint length section is not more than 50%, and the joints are staggered by 35d; for the binding connection extension, the lap length is not less than 40d, and the number of steel bar joints in the same joint length section is not more than 50%, and the distance between the two joints is not less than 1.3 times the lap length.

[0096] While processing the steel skeleton, install the embedded steel plates at the supports, embedded steel bars at the diaphragms, embedded steel bars at the guardrails, etc. At the free section of the steel strand, put a PVC tube on the outer jacket of the steel strand, and seal the two ends of the PVC tube with transparent tape. The damaged part of the PVC tube also needs to be wrapped and sealed with transparent tape.

[0097] After the steel frame is processed and formed, a small gantry crane is used to lift the steel frame from the frame to the prefabricated pedestal through special lifting tools.

[0098] Furthermore, the following provisions shall be met when installing the steel bars:

[0099] (1) The grade, diameter, number and spacing of steel bars shall comply with the design and specification requirements.

[0100] (2) Concrete pads are placed between the formwork and the steel bars to ensure the thickness of the concrete cover of the steel bars. The number of pads placed on the side and bottom of the structure or component is not less than 4 / m 2 .

[0101] (3) When the steel bar arrangement interferes with the steel strand, the steel bar position can be appropriately moved.

[0102] Reference Figure 4 As shown in the figure, after the steel skeleton is processed, the prestressed steel strands are installed in place. When installing the steel strands, the failure sleeves and spiral steel bars are installed according to the requirements of the design drawings.

[0103] Step 7: End template grinding / mold release agent application stage: Grind the end template and apply mold release agent.

[0104] Step 8: Install the end template: Fix the polished end template in place.

[0105] Further, refer to Figure 5As shown, after the steel skeleton is hoisted in place, the end formwork is installed, the connecting screw of the bender is installed, and then the steel strands are connected through connectors, and the anchors and clips are installed. Before tensioning, the tensioning pedestal, reaction frame, and tensioning equipment are inspected in detail. The prestressed steel strands can be tensioned only after they meet the requirements. Prestressed steel strands can be divided into bottom plate bundles and web bundles according to their positions. There are 36 bundles of steel strands in the bottom plate and 18 bundles of steel strands in the web. The bottom plate bundles have no vertical bends or horizontal bends, and the web bundles have vertical bends but no horizontal bends.

[0106] Step 9. Tensioning equipment inspection / calibration phase: Conduct a comprehensive inspection and calibration of the tensioning equipment.

[0107] Step 10: Prestressed tendon tensioning stage: tension the prestressed tendons according to specifications.

[0108] Further, refer to Figure 6 As shown in the figure, the prestressed steel bar adopts high-strength low-relaxation steel strand with a standard tensile strength value of fpk = 1860MPa and φS15.2mm. Its mechanical performance indicators meet the requirements of "Steel Strand for Prestressed Concrete" (GB / T5224-2014). The controlled stress under the prestressed tension anchor is 0.75fpk = 1395Mpa. Prestressed tensioning adopts dual control of tensioning force and elongation, with total tensioning force control as the main control and elongation control as the auxiliary control. When the prestressed steel strand reaches the designed tensioning force, the error between the actual elongation value and the theoretical elongation value should be controlled within 6%.

[0109] The steel strand tensioning adopts the steel strand automatic tensioning device to tension all the steel strands synchronously, and during the tensioning process, the tension of the steel strands is monitored, and the tension of a single steel strand is adjusted according to the monitoring data.

[0110] Specifically, refer to Figure 7-Figure 15 The automatic steel strand tensioning device includes a fixed base 1, on the upper surface of which a control box 2 and a multi-axis robot 3 are fixedly mounted, a PLC controller 201 is arranged inside the control box 2, and the multi-axis robot 3 is electrically connected to the PLC controller 201 inside the control box 2 through cables.

[0111] The operating end of the multi-axis robot 3 is fixedly connected with a force-applying sleeve 301 , and the inner wall of the force-applying sleeve 301 is fixedly connected with a plum wrench ring 302 .

[0112] When in use, the tension of the steel strand is adjusted by means of a plum wrench plate.

[0113] A monitoring fixing plate 4 is fixedly connected to the upper surface of the fixed base 1 away from the multi-axis robot 3 , a reinforcing support frame 5 is fixedly connected to one side surface of the monitoring fixing plate 4 , and the lower surface of the reinforcing support frame 5 is fixedly connected to the upper surface of the fixed base 1 .

[0114] When in use, the monitoring fixing plate 4 is supported and strengthened by the reinforcing support frame 5 .

[0115] A plurality of through-type tension sensors 6 are fixedly mounted on the surface of the monitoring fixed plate 4 , and the plurality of through-type tension sensors 6 correspond to the plurality of steel strands on the concrete I-beam.

[0116] The plurality of through-type tension sensors 6 are electrically connected to the PLC controller 201 inside the control box 2 via cables.

[0117] When in use, the tension of the steel strand during tensioning is monitored by the through-hole tension sensor 6, and the monitoring data is fed back to the PLC controller 201 in the control box 2, so that the control box 2 automatically controls the multi-axis robot 3 to work and adjust the tension of the steel strand.

[0118] A guide travel groove 7 is fixedly formed on the upper surface of the fixed base 1 . The two guide travel grooves 7 are symmetrically distributed with the axis of the fixed base 1 as the center. The inner wall of the guide travel groove 7 is in a T shape.

[0119] The inner wall of the guide travel groove 7 is slidably connected with a guide moving block 8, the upper surfaces of the two guide moving blocks 8 extend to the upper surface of the fixed base 1, the upper surface of the guide moving block 8 is fixedly connected with a tensioning plate 9, and the lower surface of the tensioning plate 9 is slidably connected to the upper surface of the fixed base 1.

[0120] The surface of the monitoring fixed plate 4 and the surface of the tensioning plate 9 are both in an I-shape. A force hydraulic cylinder 10 is fixedly installed on the other side surface of the monitoring fixed plate 4. Multiple force hydraulic cylinders 10 are evenly distributed on the surface of the monitoring fixed plate 4. The force hydraulic cylinder 10 is electrically connected to the PLC controller 201 inside the control box 2 through a solenoid valve.

[0121] The force applying hydraulic cylinder 10 includes a force applying hydraulic rod 11 , one end of which is fixedly connected to the surface of the tensioning plate 9 .

[0122] When in use, the force hydraulic cylinder 10 is connected to the hydraulic pump station through the hydraulic oil pipe and the solenoid valve, and is electrically connected to the PLC controller 201 inside the control box 2 through the solenoid valve and the hydraulic pump station, so that the on and off of the solenoid valve can be controlled by the PLC controller 201, and the force hydraulic rod 11 in the force hydraulic cylinder 10 can be controlled to extend or retract into the force hydraulic cylinder 10, thereby achieving the effect of driving the tensioning plate 9 to move through the force hydraulic cylinder 10.

[0123] The surface of the tensioning plate 9 is provided with a plurality of tensioning holes corresponding to the plurality of through-type tension sensors 6, the inner wall of the tensioning hole is slidably connected with a tensioning adjustment tube 12, one end of the tensioning adjustment tube 12 is fixedly connected with a conical locking tube 13, and the surface of the conical locking tube 13 is provided with a plurality of locking avoidance grooves 14 fixedly connected with the inner wall of the conical locking tube 13.

[0124] An annular barb tooth groove 15 is formed on the inner wall of the tapered locking tube 13 , and a plurality of annular barb tooth grooves 15 are evenly distributed on the inner wall of the tapered locking tube 13 .

[0125] When in use, the annular barb groove 15 contacts the surface of the steel strand, thereby increasing the contact friction between the inner wall of the conical locking tube 13 and the surface of the steel strand, thereby ensuring that the conical locking tube 13 maintains a stable locking of the steel strand during the tensioning process of the steel strand, thereby achieving a better effect of tensioning the steel strand.

[0126] A left thread groove 16 is provided on the surface of the tensioning adjustment tube 12 close to the conical locking tube 13, and the tensioning adjustment tube 12 is threadedly connected to a locking nut 17 through the left thread groove 16. A locking tube 18 is fixedly connected to the surface of the locking nut 17, and the inner wall of the locking tube 18 is conical in shape and adapted to the sliding connection with the surface of the conical locking tube 13.

[0127] When in use, the multi-axis robot 3 drives the force sleeve 301 to move and engage with the surface of the locking tube 18, and the plum blossom spanner ring 302 is used to engage with the surface of the locking nut 17. Then, the multi-axis robot 3 drives the force sleeve 301 and the plum blossom spanner ring 302 to rotate, drives the locking nut 17 to rotate, drives the locking tube 18 to move rightward, and squeezes the conical locking tube 13 through the conical surface of the inner wall of the locking tube 18 to make the conical locking tube 13 move toward the axis to lock the steel strand. The multi-axis robot 3 drives the plum blossom spanner to rotate in the opposite direction, drives the locking nut 17 to rotate in the opposite direction, drives the locking tube 18 to move to the left, releases the squeezing and tightening force on the conical locking tube 13, and makes the conical locking tube 13 release the clamping and locking of the steel strand.

[0128] A right thread groove 19 and a stop travel groove 20 are respectively formed on the surface of the tensioning adjustment tube 12 away from the tapered locking tube 13 . The plurality of stop travel grooves 20 are distributed in a ring array with the axis of the tensioning adjustment tube 12 as the center.

[0129] The inner wall of the stop stroke groove 20 is rectangular in shape, and a stop limit strip 21 is slidably connected to the inner wall of the stop stroke groove 20. The surfaces of the plurality of stop limit strips 21 are matched with the inner wall of the stop stroke groove 20, and the surfaces of the stop limit strips 21 are fixedly connected to the inner wall of the tensioning hole.

[0130] The surface of the tensioning adjustment tube 12 is threadedly connected with an adjustment nut 22 through a right thread groove 19 , and the surface of the adjustment nut 22 is slidably connected with the surface of the tensioning plate 9 .

[0131] Specifically, when the steel strands are tensioned, the operation is as follows: first, all the corresponding steel strands on the concrete I-beam are transmitted to the through-type sensor, and then pass through the monitoring fixed plate 4 through the through-type sensor, enter the tensioning adjustment tube 12, and then pass through the conical locking tube 13. After all the steel strands pass through the conical locking tube 13, the multi-axis robot 3 is automatically controlled to work through the PLC controller 201 in the control box 2.

[0132] The multi-axis robot 3 drives the force sleeve 301 to move and engage with the surface of the locking tube 18, and engages with the surface of the locking nut 17 through the plum blossom wrench ring 302. Then, the multi-axis robot 3 drives the force sleeve 301 and the plum blossom wrench ring 302 to rotate, drives the locking nut 17 to rotate, drives the locking tube 18 to move to the right, and squeezes the conical locking tube 13 through the conical surface of the inner wall of the locking tube 18, so that the conical locking tube 13 moves toward the axis to lock the steel strand.

[0133] Then the PLC controller 201 in the control box 2 controls the operation of the hydraulic pump station and the force hydraulic cylinder 10. The force hydraulic rods 11 in the multiple force hydraulic cylinders 10 extend simultaneously, pushing the tensioning plate 9 to move away from the monitoring fixed plate 4, tensioning the steel strands. During the tensioning process, the tension of the steel strands is monitored by the through-type tension sensor 6 and fed back to the controller in the control box 2. After tensioning to the set threshold, the PLC controller 201 automatically controls the force hydraulic cylinder 10 to stop working, and then adjusts the tension of the steel strands with insufficient or excessive tensioning force according to the monitoring data of each through-type sensor.

[0134] During adjustment, according to the monitoring data of the through-type tension sensor 6, the PLC controller 201 automatically controls the operation of the multi-axis robot 3, and the multi-axis robot 3 drives the force sleeve 301 and the plum blossom spanner ring 302 to move, so that the inner wall of the plum blossom spanner ring 302 is sleeved with the adjusting nut 22, thereby driving the adjusting nut 22 to rotate.

[0135] When the tension is small, the multi-axis robot 3 drives the adjusting nut 22 to reverse through the force sleeve 301 and the plum wrench ring 302. The adjusting nut 22 reverses and drives the tensioning adjusting tube 12 to move from the tensioning hole toward the multi-axis robot 3 to tension the steel strand.

[0136] When the tension is too large, the multi-axis robot 3 drives the adjusting nut 22 to rotate forward through the force sleeve 301 and the plum blossom wrench ring 302. The adjusting nut 22 rotates forward to drive the tensioning adjusting tube 12 to move from the tensioning hole toward the monitoring fixing plate 4 to release the tension of the steel strand.

[0137] By setting up an automatic tensioning device for steel strands, during the prefabrication process of the concrete I-beam, the tensioning plate 9 is pushed to move by the force-applying hydraulic cylinder 10 to synchronously tension a plurality of steel strands, and the tension data of the plurality of steel strands during the tensioning process are monitored by a plurality of through-type tension sensors 6 and fed back to the PLC controller 201, and then the multi-axis robot 3 automatically rotates the adjusting nut 22 to adjust the tensioning tension of the steel strands, thereby achieving the effect of automatic prestressing tensioning and adjustment of the concrete I-beam.

[0138] Prestressed steel strand tensioning process: 0 → initial stress (15% σcon) → σcon (holding load for 2 minutes) → anchoring. After the steel strand tensioning is completed, the connecting screw of the bender is wrapped with foam glue to ensure that the screw can be removed after the precast beam concrete construction is completed.

[0139] Step 11: Side template grinding / brushing release agent stage: Grind the side template and apply release agent.

[0140] Step 12: Install the side formwork: Install the polished side formwork in place.

[0141] Step 13: Concrete pouring / vibration stage: Pour the concrete evenly and vibrate it to make it dense using a vibrating rod or a flat vibrator.

[0142] Furthermore, before pouring concrete, the formwork, steel bars and embedded parts should be inspected and recorded. Only when they meet the design requirements can they be poured. The debris, stagnant water in the formwork and dirt on the steel bars should be cleaned up, and any gaps in the formwork should be filled tightly.

[0143] After the concrete is transported to the construction site, an on-site inspection is carried out: a slump test is carried out as required, and the workability of the concrete is observed. It can only be used if it meets the requirements of the specifications; concrete test blocks are made to measure the concrete strength and elastic modulus.

[0144] The concrete was constructed using a small gantry crane with a 2m3 hopper. The method of "layered pouring, step-by-step, and one-time pouring" was adopted. The first layer was poured from the head to the tail of the precast beam, the second layer was poured from the web, and the third layer was poured from the top. During the pouring process, a special person was assigned to check whether there was any leakage.

[0145] When pouring concrete, mechanical vibration is performed by a combination of an insert vibrator and an attached vibrator, and the vibration is performed by a dedicated person. Since the web of the I-beam is densely reinforced, narrow, and prestressed, the bottom plate is wider than the web, and a chamfer is formed between the two. It is inconvenient to use an insert vibrator on the bottom plate, and it is difficult to vibrate it densely, so the part below the web is vibrated by an attached vibrator.

[0146] An attached vibrator is installed on the precast beam formwork to vibrate the concrete, and avoid the vibrator from colliding with steel strands, embedded parts, formwork, etc. Each vibration is carried out until the concrete no longer sinks, no bubbles rise, a thin layer of cement slurry appears on the surface and has a uniform appearance, until the concrete pouring is completed. In order to ensure the roughness of the top surface, the surface of the precast beam top plate is smoothed with a wooden trowel, and the slurry is collected twice before the initial setting. After the concrete bleeding phenomenon stops completely, the surface is roughened.

[0147] After the concrete strength reaches the specification and design requirements, the side formwork will be removed. First, remove the tension screws of the precast beam formwork, then remove the formwork adjustment device (formwork leg) under the side formwork, then remove the connecting bolts between the side formworks, and use a small gantry crane to remove the side formwork. After the side formwork is removed, the embedded steel bars of the diaphragm are chiseled out and straightened in time, and the concrete at the connection with the diaphragm is roughened. After the steel strands are tensioned, remove the connectors, and then remove the end formwork.

[0148] Step 14: Test block preparation stage: Prepare concrete test blocks according to standards to test their performance.

[0149] Step 15. Concrete curing stage: ensure that the concrete is fully cured under specified conditions.

[0150] Furthermore, in step 15, the concrete curing stage, the concrete is spray cured. After the concrete is finally set, the exposed surface is covered with geotextile and watered by an automatic spray system. The automatic spray system is arranged on both sides and the top surface of the precast beam. The curing time meets the requirements of the specification, and the time interval of the spraying is to keep the concrete surface in a moist state at all times.

[0151] Step 16, prestressed tendon release stage: After the concrete reaches the design strength, gradually release the tension of the prestressed tendons.

[0152] Furthermore, according to the design requirements, the prestressed steel strands are tensioned after the precast beam concrete reaches 90% of the designed concrete strength grade and the elastic modulus reaches 90% of the 28d elastic modulus. Before tensioning, the connecting screw of the bending device is removed first, and then tensioning is performed. The tensioning is completed in several times, and it is strictly forbidden to complete the tensioning in one time.

[0153] Step 17: Lifting to the beam storage area: Safely lift the prefabricated I-beam to the designated storage area.

[0154] Furthermore, after the prestressing is released, the precast beams are stored in the beam storage area by two 130t gantry cranes. Avoid any impact and collision on the beams and slabs during the lifting process, and do not store more than two layers of beams in the beam storage area. The first layer of I-beams is placed directly on the beam storage pedestal, and rubber sheets are laid on the bottom to avoid damage to the bottom of the I-beams. When storing two layers of beams, concrete block pads are set on the top of the first layer of I-beams. The concrete blocks are 110cm long, 50cm wide, and 38cm high. C30 concrete is used. One concrete block pad is set at each end of the I-beam and is arranged directly above the beam storage pedestal.

[0155] By setting steps one to seventeen, during the prefabrication of concrete I-beams, by optimizing the prefabrication process of concrete I-beams and cooperating with the automatic tensioning device for steel strands, multiple steel strands can be tensioned simultaneously at one time, and the tension of the steel strands can be adjusted according to the tensioning monitoring data to improve the tensioning accuracy, thereby achieving the effect of improving the quality of bridge components and production efficiency.

[0156] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A long-line prefabrication system for prestressed concrete I-beams by folding line pretensioning method, characterized in that: The following steps are involved: Step 1: Construction preparation stage: clean and level the prefabrication site; Step 2: Tensioning system design and construction phase: Design and construct the tensioning system based on the bridge design parameters; Step 3: Grinding the bottom template / brushing the release agent: Grind the surface of the bottom template and evenly apply the release agent; Step 4: Install the bottom template: accurately install the processed bottom template; Step 5: Install the prestressed tendons / connectors: Arrange the prestressed tendons according to the design drawings and connect the connectors; Step 6: Steel cage processing / hoisting stage: Process the steel cage according to the design requirements and hoist it to the correct position; Step 7: Grinding / brushing release agent on the end template: Grind the end template and apply release agent; Step 8: Install the end template: fix the polished end template in place; Step 9: Inspection / calibration of tensioning equipment: Conduct comprehensive inspection and calibration of tensioning equipment; Step 10, prestressed tendon tensioning stage: prestressed tendon steel strands are tensioned according to the specifications. The steel strands are tensioned by an automatic steel strand tensioning device to tension all steel strands synchronously. During the tensioning process, the tension of the steel strands is monitored, and the tension of a single steel strand is adjusted according to the monitoring data. Step 11: Side template grinding / brushing release agent stage: Grind the side template and apply release agent; Step 12: Install the side formwork: Install the polished side formwork in place; Step 13: Concrete pouring / vibration stage: pour concrete evenly and vibrate it to make it dense using a vibrating rod or a flat vibrator; Step 14: Test block preparation stage: Prepare concrete test blocks according to standards to test their performance; Step 15: Concrete curing stage: ensure that the concrete is fully cured under the specified conditions; Step 16: Prestressed tendon release stage: After the concrete reaches the design strength, gradually release the tension of the prestressed tendons; Step 17: Lifting to the beam storage area: Safely lift the prefabricated I-beam to the designated storage area.

2. The long-line prefabrication system of prestressed concrete I-beams by fold-line pretensioning method according to claim 1 is characterized by: The construction preparation stage also includes prefabrication site construction, technical preparation, site preparation, measurement preparation and test preparation; The prefabrication yard is constructed according to the prefabricated beam yard design drawing to carry out the construction of the prefabricated pedestal, the processing of the steel bar binding frame, and the processing of the prefabricated beam formwork.

3. The long-line prefabrication system of prestressed concrete I-beams by fold-line pretensioning method according to claim 1 is characterized by: During the steel cage processing / hanging stage, the steel bars are processed into semi-finished products in the steel bar processing workshop, transported to the steel bar binding cradle area of ​​the prefabricated beam yard, and respectively bound into bottom web and top plate parts. The prestressed steel strands are installed while the steel bar skeleton of the bottom web of the prefabricated beam is processed; The steel cage processing / hanging stage also includes steel bar storage, steel bar cutting and bending, and steel bar installation.

4. The long-line prefabrication system of prestressed concrete I-beams by folding line pretensioning method according to claim 1 is characterized in that: In the step fifteen, during the concrete curing stage, the concrete is spray-cured. After the concrete has finally set, the exposed surface is covered with geotextile and watered by an automatic sprinkler system. The automatic sprinkler system is arranged on both sides and the top surface of the precast beam. The curing time meets the requirements of the specifications, and the time interval of the spraying is determined to keep the concrete surface in a moist state at all times.

5. The long-line prefabrication system of prestressed concrete I-beams by fold-line pretensioning method according to claim 1 is characterized by: The steel strand automatic tensioning device comprises a fixed base (1), a control box (2) and a multi-axis robot (3) are fixedly mounted on the upper surface of the fixed base (1), a PLC controller (201) is arranged inside the control box (2), and the multi-axis robot (3) is electrically connected to the PLC controller (201) inside the control box (2) via a cable; The operating end of the multi-axis robot (3) is fixedly connected to a force-applying sleeve (301), and the inner wall of the force-applying sleeve (301) is fixedly connected to a plum wrench ring (302).

6. The long-line prefabrication system of prestressed concrete I-beams by fold-line pretensioning method according to claim 5, characterized in that: A monitoring fixing plate (4) is fixedly connected to the upper surface of one end of the fixed base (1) away from the multi-axis robot (3), a reinforcing support frame (5) is fixedly connected to one side surface of the monitoring fixing plate (4), and a lower surface of the reinforcing support frame (5) is fixedly connected to the upper surface of the fixed base (1); A plurality of through-type tension sensors (6) are fixedly mounted on the surface of the monitoring fixed plate (4), and the plurality of through-type tension sensors (6) correspond to a plurality of steel strands on the concrete I-beam; The plurality of through-type tension sensors (6) are electrically connected to the PLC controller (201) inside the control box (2) via cables.

7. The long-line prefabrication system of prestressed concrete I-beams by folding line pretensioning method according to claim 6 is characterized by: A guide travel groove (7) is fixedly provided on the upper surface of the fixed base (1), the two guide travel grooves (7) are symmetrically distributed with the axis of the fixed base (1) as the center, and the inner wall of the guide travel groove (7) is T-shaped; The inner wall of the guide travel groove (7) is slidably connected to a guide moving block (8), the upper surfaces of the two guide moving blocks (8) extend to the upper surface of the fixed base (1), the upper surface of the guide moving block (8) is fixedly connected to a tensioning plate (9), and the lower surface of the tensioning plate (9) is slidably connected to the upper surface of the fixed base (1); The surface of the monitoring fixed plate (4) and the surface of the tensioning plate (9) are both in an I-shape, and a force-applying hydraulic cylinder (10) is fixedly installed on the other side surface of the monitoring fixed plate (4). A plurality of the force-applying hydraulic cylinders (10) are evenly distributed on the surface of the monitoring fixed plate (4), and the force-applying hydraulic cylinders (10) are electrically connected to a PLC controller (201) inside the control box (2) via a solenoid valve; The force-applying hydraulic cylinder (10) comprises a force-applying hydraulic rod (11), one end of which is fixedly connected to the surface of the tensioning plate (9).

8. The long-line prefabrication system of prestressed concrete I-beams by folding line pretensioning method according to claim 7 is characterized by: The surface of the tensioning plate (9) is provided with a plurality of tensioning holes corresponding to the plurality of through-type tension sensors (6); the inner wall of the tensioning hole is slidably connected with a tensioning adjustment tube (12); one end of the tensioning adjustment tube (12) is fixedly connected with a conical locking tube (13); the surface of the conical locking tube (13) is provided with a plurality of locking avoidance grooves (14) fixedly connected with the inner wall of the conical locking tube (13); The inner wall of the conical locking tube (13) is provided with an annular barb tooth groove (15), and a plurality of the annular barb tooth grooves (15) are evenly distributed on the inner wall of the conical locking tube (13).

9. The long-line prefabrication system of prestressed concrete I-beams by folding line pretensioning method according to claim 8, characterized in that: A left thread groove (16) is provided on the surface of the tensioning adjustment tube (12) close to the conical locking tube (13); the tensioning adjustment tube (12) is threadedly connected to a locking nut (17) through the left thread groove (16); a locking tube (18) is fixedly connected to the surface of the locking nut (17); the inner wall of the locking tube (18) is conical in shape and is adapted to be slidably connected to the surface of the conical locking tube (13).

10. The long-line prefabrication system of prestressed concrete I-beams by folding line pretensioning method according to claim 9, characterized in that: The surface of the tensioning adjustment tube (12) away from the tapered locking tube (13) is respectively provided with a right thread groove (19) and a stop travel groove (20), and a plurality of the stop travel grooves (20) are distributed in a ring array with the axis of the tensioning adjustment tube (12) as the center; The inner wall of the stop travel groove (20) is in a rectangular shape, and a stop limit strip (21) is slidably connected to the inner wall of the stop travel groove (20), and the surfaces of the plurality of stop limit strips (21) are adapted to the inner wall of the stop travel groove (20), and the surfaces of the stop limit strips (21) are fixedly connected to the inner wall of the tensioning hole; The surface of the tensioning adjustment tube (12) is threadedly connected to an adjustment nut (22) via the right thread groove (19), and the surface of the adjustment nut (22) is slidably connected to the surface of the tensioning plate (9).

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