CN118269219A - Concrete prefabricated pi-shaped beam and construction method - Google Patents

Abstract

The invention relates to a concrete precast pi-shaped beam and a construction method thereof, wherein the construction method comprises the following steps: (1) binding pi beam steel rib frames; (2) construction of a counterforce wall; (3) installing a core mold, a bottom mold and a brush spacer; (4) placing a steel reinforcement framework and penetrating a prestressed steel strand; (5) stretching the prestressed tendons; (6) installing a side die and an end die; (7) casting concrete; (8) heating and curing the steel core mould; (9) removing the mould and releasing the prestressed tendons; and (10) moving the beam and storing the beam plate. The invention develops the pi beam reinforcement jig which is in a pi structure, and pi beam reinforcements are bound on the jig, so that the construction efficiency and the binding quality of the reinforcements can be greatly improved; according to the invention, a tensioning counterforce wall structure is developed, the bearing capacity is improved by arranging a plurality of steel pipe piles at the bottom of the counterforce wall, the automatic sliding effect of the beam is improved by arranging the pulley at the bottom of the movable beam, and the prestress loss of steel strands is reduced by a single-side tensioning technology.

Description

Concrete prefabricated pi-shaped beam and construction method

Technical Field

The invention relates to a concrete precast pi-shaped beam and a construction method thereof, which are mainly suitable for the construction of a small concrete precast pi-shaped beam of a pile-slab bridge.

Background

The pile plate type bridge structure adopts prefabricated components such as a box beam, a T beam, an I beam, a hollow slab and the like which are commonly used, the prestressed steel beam is tensioned to enable the main beam to generate opposite camber, when the opposite camber value generates deviation, the accurate positioning of the steel bars and the accurate erection of the beam bodies are often affected, the transverse connection between the beam bodies is difficult, and even local dislocation is formed when serious, so that the bridge functions and the appearance are affected. In recent years, designers have proposed an original bridge structural form: the pile plate type bridge prefabricates pi-shaped beam, and the beam has the following characteristics:

(1) The single pi-shaped girder is formed by integrally prefabricating a T-shaped double girder and a bridge deck supported by the T-shaped double girder;

(2) According to the stress requirement of the joint, the width of the cantilever part of the bridge deck can be smaller than 1/2 of the distance between the webs of the main girder;

(3) And transverse baffles are arranged at the end parts and the midspan of the pi-shaped beam structure, the transverse baffles and the T-shaped double main beams are integrally prefabricated, and no transverse baffles are arranged between two adjacent spliced pi-shaped beams.

(4) The pi-shaped beam and the diaphragm plates thereof are integrally prefabricated in a factory and transported to a construction site, and then the prefabricated pi-shaped beam components are transversely assembled in the construction site.

In the production prefabrication process of the pi-shaped beam, due to the lack of intelligent management and control production line and technology, the construction equipment and construction technology of the existing precast concrete beam are adopted, so that in the production prefabrication process of the pi-shaped beam, the formwork system is low in formwork supporting efficiency and poor in turnover usability, concrete pouring is uneven, the tensile stress loss of the precast pi-shaped beam is large, the large-scale production efficiency is low, the winter maintenance time is long, the quality performance is poor, and great influence is brought to the large-scale popularization and application of the pile-slab bridge.

The invention aims to improve the reinforcement binding efficiency of pi-shaped beams, reduce the tension stress loss of prefabricated pi-shaped beams, improve the turnover use efficiency of a formwork system, ensure the uniform pouring of concrete, reduce the maintenance time in winter and urgently need to invent a simple and effective concrete prefabricated pi-shaped beam and a construction method.

Disclosure of Invention

In order to achieve the technical purpose, the invention adopts the following technical scheme:

the construction method of the concrete precast pi-shaped beam comprises the following specific steps:

Step one, binding pi beam steel rib frames:

Manufacturing a pi beam steel bar jig frame in a factory in advance according to the design size, wherein the pi beam steel bar jig frame is of a pi structure, and binding a pi beam steel bar framework in the pi beam steel bar jig frame;

Step two, construction of a counterforce wall: a plurality of steel pipe piles are arranged on a foundation according to the designed position, steel bars are bound at the tops of the steel pipe piles, a formwork is supported at the outer sides of the steel bars, concrete is poured to form counter-force walls, beam-making pedestals are poured between the counter-force walls at the two ends, a fixed beam is arranged at the back of the counter-force walls, a beam splitting plate is arranged on the fixed beam, a plurality of steel strand penetrating holes and jack butt joint plates are arranged on the beam splitting plate, concrete is poured on the foundation at the outer side of the fixed beam at one end to form a sliding pedestal, a sliding rail is arranged at the top of the sliding pedestal, pulleys are arranged at the bottom of the movable beam, and the pulleys at the bottom of the movable beam are arranged on the sliding rail at the top of the sliding pedestal so that the movable beam can slide along the sliding rail on the sliding pedestal;

step three, installing a core mold, a bottom mold and a brush isolating agent:

The mandrel comprises a bottom die, a steel hinge, an L-shaped integral steel mandrel and an L-shaped mandrel steel skeleton, wherein a spacer is brushed on the surface of the mandrel before installation, a resistance coil is wound on the outer side of the L-shaped integral steel mandrel, a plurality of fine adjustment jacks are supported on a girder preparation pedestal, an adjusting plate is laid on the top of each fine adjustment jack in a flat mode, the bottom die is fixedly arranged on the adjusting plate, the L-shaped integral steel mandrel is connected with the bottom die through the steel hinge, and the L-shaped mandrel steel skeleton is arranged on the outer side of the L-shaped integral steel mandrel; an adjusting screw rod is arranged on the adjusting plate, the lower end of the adjusting screw rod is hinged with the adjusting plate, and the upper end of the adjusting screw rod is hinged with the L-shaped core model steel skeleton; the angle of the L-shaped integral steel core mold is adjusted through an adjusting screw rod, and a connecting plate is arranged between two adjacent L-shaped core mold steel frameworks;

Fourthly, placing a steel reinforcement framework and penetrating a prestressed steel hinge line:

The method comprises the steps of integrally lifting and placing a bound pi beam steel rib frame in a core mold, arranging finish rolling threads on a movable beam, arranging a plurality of jacks between the movable beam and a fixed beam, wherein one end of each jack is fixedly arranged on a jack butt joint disc on a beam splitting plate, the other end of each jack is connected with the movable beam, sequentially penetrating the fixed end of a prestress steel hinge wire through a counter-force wall at one end, the fixed beam and a steel hinge wire penetrating hole on the beam splitting plate, anchoring, sequentially penetrating the movable end of the prestress steel hinge wire through the counter-force wall at the other end, the fixed beam and the steel hinge wire penetrating hole on the beam splitting plate, and then connecting the prestress steel hinge wire with the finish rolling threads, wherein the finish rolling threads on the movable beam are connected with the prestress steel hinge wire through a wire rod connector;

Step five, tensioning the prestressed tendons:

the prestressed steel strand is integrally tensioned by a jack and integrally released;

step six, installing side dies and end dies:

A jacking is supported on two sides of a core mould on a girder preparation pedestal, side moulds are installed on the jacking, the side moulds are longitudinally assembled in a through length mode, end plates are inserted into slots of two side moulds corresponding to the end parts, and opposite side moulds are provided with opposite pull connecting rods;

step seven, pouring concrete:

The concrete funnel, the door-shaped vertical frame and the blanking pump pipe are assembled into a whole in a factory in advance, the travelling wheel is arranged at the lower end of the door-shaped vertical frame, the travelling wheel is pushed to the upper part of the core mold, concrete is poured into the concrete funnel, and the plurality of blanking pump pipes are utilized to uniformly distribute materials into the core mold;

step eight, heating and curing the steel core die:

Electrifying a resistance coil on the L-shaped integral steel core mould, heating the L-shaped integral steel core mould, covering the top surface of pi beam concrete by geotextile, and spraying, moisturizing and curing;

Step nine, removing the die and releasing the prestressed tendons:

When the strength of the pi beam concrete reaches 2.5Mpa, loosening the opposite-pull connecting rod, and sequentially removing the end plate and the side die; after the concrete strength of the pi beam reaches 90% of the design strength and the concrete age is not less than 7 days, firstly loosening an anchor nut from the stretching end of the stretching prestress steel strand and stretching the prestress steel strand, and then cutting off the prestress steel strand;

step ten, moving the beam and storing the beam plate:

And (5) lifting and transporting the pi beam to a beam storage area by adopting a gantry crane.

Preferably, in the seventh step, in the third step, an adjustable supporting rod is mounted on the adjusting plate; after the angle of the L-shaped integral steel core die is adjusted, the upper end of the adjustable supporting rod is propped against the lower end surface of the L-shaped integral steel core die and supports the L-shaped integral steel core die.

Preferably, in the fifth step, the tensioning procedure of the prestressed steel strand is as follows: and (3) initially tensioning by adopting a jack, tensioning the whole prestress steel strand to design control stress by adopting the jack for 5min after reaching 20% sigma con, and anchoring the prestress steel strand after the tensioning control stress is in a stable state.

Preferably, one end of the side die is provided with a groove, the other end of the side die is provided with a bulge, the groove is matched with the bulge, and the adjacent side dies are connected in a jogged manner by the groove and the bulge.

In the seventh step, the pi beam concrete is poured in a longitudinal section and a horizontal layer by layer, and the pouring height of each layer is not more than 30cm.

Preferably, in the step ten, pi Liang Fang is stacked on the sleeper, pi beam plates are stacked for 2 layers, and square timber support is used between two layers of pi beams.

A concrete precast pi-shaped beam is constructed by a construction method of the concrete precast pi-shaped beam.

The invention has the following characteristics and beneficial effects:

(1) The invention develops the pi beam reinforcement jig which is in a pi structure, and pi beam reinforcements are bound on the jig, so that the construction efficiency and the binding quality of the reinforcements can be greatly improved.

(2) According to the invention, a tensioning counterforce wall structure is developed, the bearing capacity is improved by arranging a plurality of steel pipe piles at the bottom of the counterforce wall, the automatic sliding effect of the beam is improved by arranging the pulley at the bottom of the movable beam, and the prestress loss of steel strands is reduced by a single-side tensioning technology.

(3) According to the invention, the bottom die height is controlled by the plurality of fine adjustment jacks, the angle of the core die is controlled by the adjusting screw rod, the side die assembling efficiency is improved by the groove and bulge engaging structure, and the whole die supporting system is efficient and quick and can be repeatedly recycled.

(4) According to the invention, the resistance coil heating template is arranged on the L-shaped integral steel core mould, so that the curing time of concrete can be shortened in winter construction.

(5) According to the invention, the plurality of blanking pump pipes are adopted for uniform distribution, so that the concrete pouring uniformity of the pi beam can be ensured, and the quality of the pi beam can be improved.

Drawings

FIG. 1 is a diagram of a pi beam steel bar framework of the invention;

FIG. 2 is a block diagram of a pi beam rebar jig of the present invention;

FIG. 3 is a single-sided prestress tensioning block diagram of the prestress steel strand of the invention;

FIG. 4 is a block diagram of a beam splitter plate of the present invention;

FIG. 5 is a block diagram of a core mold according to the present invention;

FIG. 6 is a diagram of the pi beam formwork architecture of the present invention;

FIG. 7 is a longitudinal connection diagram of side modules of the pi beam formwork system of the present invention;

FIG. 8 is a diagram of the connection of a side form to a header plate in accordance with the present invention;

FIG. 9 is a diagram of the concrete structure of the pi beam of the present invention;

FIG. 10 is a diagram of a structure of uniformly pouring pi beam concrete in a blanking pump pipe.

Wherein: 1-pi beam steel bar jig frame; 2-pi beam reinforcement cage; 3-prestress steel strand; 4-counterforce wall; 5-fixing the cross beam; 6-beam splitting plates; 7-jack; 8-moving a cross beam; 9-pulleys; 10-sliding rails; 11-a sliding pedestal; 12-penetrating the steel strand into the hole; 13-jack butt-joint disc; 14-beam making pedestal; 15-fine tuning jack; 16-adjusting plate; 17-a bottom die; 18-steel hinging; 19-adjusting a screw rod; 20-steel pipe piles; 21-foundation; a 22-L type integral steel core mold; 23-resistance coil; 24-L core model steel skeleton; 25-an adjustable support bar; 26-connecting plates; 27-jacking; 28-side mold; 29-a tie rod; 30-grooves; 31-bulge; 32-end plates; 33-slots; 34-pi beam concrete; 35-travelling wheels; 36-door-type stand; 37-diagonal bracing; 38-concrete funnel; 39-blanking pump pipe.

Detailed Description

The invention relates to a steel pipe pile and counterforce wall connecting structure, a steel core mold manufacturing process and a connecting structure, a jack working principle, an adjusting screw rod working principle, a jacking structure, various steel plate welding technologies, steel bar binding technologies, concrete pouring technical requirements and the like, and the invention is not further described, and focuses on the embodiment of the structure.

1-2, Wherein FIG. 1 is a diagram of pi beam reinforcement frameworks bound on a pi beam reinforcement jig, and FIG. 2 is a diagram of a pi beam reinforcement jig structure of the invention; the pi beam steel bar jig 1 is in a pi structure, and the pi beam steel bar framework 2 is bound and welded on the pi beam steel bar jig 1.

As shown in fig. 3-4, fig. 3 is a prestress single-side prestress tensioning structure diagram of a prestress steel strand, which comprises a prestress steel strand 3, a counter-force wall 4, a fixed beam 5, a beam splitting plate 6, a jack 7, a movable beam 8, a pulley 9, a sliding rail 10, a sliding pedestal 11, a steel strand penetrating hole 12, a jack butting disc 13, steel pipe piles 20 and a foundation 21, wherein a plurality of steel pipe piles 20 are arranged at the lower part of the counter-force wall 4, the steel pipe piles 20 are driven into the foundation 21 to a certain depth, the back of the counter-force wall 4 is provided with the fixed beam 5, the beam splitting plate 6 is provided with a plurality of steel strand penetrating holes 12 and the jack butting disc 13, the prestress steel strand 3 is split through the beam splitting plate 6, and the prestress steel strand 3 is fixed after penetrating through the steel strand penetrating holes 12.

Further, the movable cross beam 8 carries out lifting and horizontal moving through the jack 7, the base of the jack 7 is fixed on a jack butt joint disc 13 on the beam splitting plate 6, and one end, far away from the base, of the jack 7 is jacked on the movable cross beam 8. The pulley 9 is provided at the bottom of the movable cross beam 8, the pulley 9 is slidable on a rail 10 of a slide base 11, and the slide base 11 is provided on a foundation 21.

As shown in fig. 5-6, fig. 5 is a pi beam formwork system structure diagram, which comprises a beam making pedestal 14, a fine tuning jack 15, an adjusting plate 16, a bottom die 17, a steel hinge 18, an adjusting screw rod 19, an L-shaped integral steel mandrel 22, a resistance coil 23, an L-shaped mandrel steel skeleton 24, an adjustable supporting rod 25 and a connecting plate 26, wherein a plurality of fine tuning jacks 15 are arranged on the beam making pedestal 14, the adjusting plate 16 is arranged on the top of the fine tuning jack 15, the fine tuning jack 15 can control the height of the adjusting plate 16, the prefabricated pi beam is used for formwork supporting on the adjusting plate 16, the bottom die 17 is connected with the L-shaped integral steel mandrel 22 through the steel hinge 18, the bottom die 17 is arranged on the adjusting plate 16, and the L-shaped integral steel mandrel 22 can rotate relative to the bottom die 17. The outside of the integral steel mandrel 22 of L type sets up L core model steel skeleton 24 as the atress stupefied, and L core model steel skeleton 24 carries out angle regulation through adjusting screw 19, and adjusting screw 19's one end articulates with regulating plate 16, and adjusting screw 19's the other end articulates with L core model steel skeleton 24. The L-shaped core model steel skeleton 24 is supported by an adjustable supporting rod 25, the adjustable supporting rod 25 is fixed on the adjusting plate 16, and the upper end of the adjustable supporting rod 25 is supported at the bottom of the L-shaped core model steel skeleton 24. The L-shaped integral steel core mold 22 is wound with a resistance coil 23, and the resistance coil 23 can heat the L-shaped integral steel core mold 22 after being electrified.

Further, a tie plate 26 is provided between adjacent L-core mold steel backbones 24 to improve integrity.

As shown in fig. 6-8, fig. 7 is a longitudinal connection diagram of side modules of a pi beam formwork system, which comprises a jacking 27, side modules 28, a counter-pulling connecting rod 29, a groove 30, a protrusion 31, an end plate 32 and a slot 33, wherein the bottom of the side modules 28 is supported by the jacking 27, the height of the side modules 28 is adjusted by the jacking 27, the side modules 28 can be spliced, one end of each side module 28 is provided with the groove 30, the other end is provided with the protrusion 31, and the groove 30 is matched with the protrusion 31. The two adjacent side dies 28 are longitudinally connected through the grooves 30 and the protrusions 31 in a jogged way, the edge parts of the side dies 28 positioned at the extreme ends are provided with slots 33, the end plates 32 can be directly inserted into the slots 33 of the two side dies 28 corresponding to the extreme ends, and opposite side dies 28 are provided with opposite pull connecting rods 29.

As shown in fig. 9-10, fig. 10 is a structure diagram of a blanking pump pipe uniformly pouring pi beam concrete, which comprises a beam making pedestal 14, side forms 28, pi beam concrete 34, travelling wheels 35, a door-shaped vertical frame 36, diagonal braces 37, a concrete funnel 38 and a blanking pump pipe 39, wherein the pi beam concrete 34 is uniformly distributed and poured through the blanking pump pipe 39, the top ends of the blanking pump pipes 39 are connected with the concrete funnel 38, the number of the blanking pump pipes 39 can be multiple according to the size of the pi beam, the concrete funnel 38 is supported through the door-shaped vertical frame 36, the concrete funnel 38 is fixedly arranged at the top ends of the door-shaped vertical frames 36, the travelling wheels 35 are arranged at the bottoms of the door-shaped vertical frames 36, the door-shaped vertical frames 36 are supported at two sides of the side forms 28, the door-shaped vertical frames 36 are reinforced by the diagonal braces 37, and a triangular reinforcing structure is formed between the door-shaped vertical frames 36.

The construction method of the concrete precast pi-shaped beam comprises the following steps:

(1) Pi beam steel rib frame binding

And manufacturing a pi beam steel bar jig frame 1 in a factory in advance according to the design size, wherein the pi beam steel bar jig frame 1 is of a pi structure, and binding a pi beam steel bar framework 2 in the pi beam steel bar jig frame 1.

(2) Counterforce wall construction

A plurality of steel pipe piles 20 are arranged on a foundation 21 according to the designed position, steel bars are bound at the tops of the steel pipe piles 20, a formwork is supported at the outer sides of the steel bars, concrete is poured to form counter-force walls 4, beam-making pedestals 14 are poured between the counter-force walls 4 at the two ends, a fixed beam 5 is arranged at the back of the counter-force walls 4, a beam splitting plate 6 is arranged on the fixed beam 5, a plurality of steel hinge line penetrating holes 12 and jack butt joint plates 13 are arranged on the beam splitting plate 6, concrete is poured on the foundation 21 with a certain distance outside the fixed beam 5 at one end to form a sliding pedestal 11, a sliding rail 10 is arranged at the top of the sliding pedestal 11, pulleys 9 are arranged at the bottom of a movable beam 8, the movable beam 8 is placed on the sliding pedestal 11, and the pulleys 9 at the bottom of the movable beam 8 are placed on the sliding rail 10 at the top of the sliding pedestal 11 to enable the movable beam 8 to slide along the sliding rail 10 on the sliding pedestal 11.

(3) Mounting core mould, bottom mould and brush isolating agent

The pi beam template adopts a brand new steel mould, the core mould comprises a bottom mould 17, a steel hinge 18, an L-shaped integral steel core mould 22 and an L-shaped core mould steel skeleton 24, a spacer is brushed on the surface of the core mould before installation, a resistance coil is wound on the outer side of the L-shaped integral steel core mould 22, a plurality of fine tuning jacks 15 are supported on a beam making pedestal 14, an adjusting plate 16 is laid on the top of each fine tuning jack 15 in a flat manner, the bottom mould 17 is fixedly arranged on the adjusting plate 16, the L-shaped integral steel core mould 22 is connected with the bottom mould 17 through the steel hinge 18, and the L-shaped core mould steel skeleton 24 is arranged on the outer side of the L-shaped integral steel core mould 22; an adjusting screw rod 19 and an adjustable supporting rod 25 are arranged on the adjusting plate 16, the lower end of the adjusting screw rod 19 is hinged with the adjusting plate 16, and the upper end of the adjusting screw rod 19 is hinged with an L-type core model steel skeleton 24; the angle of the L-shaped integral steel core mold 22 is adjusted through the adjusting screw rod 19, and after the angle adjustment of the L-shaped integral steel core mold 22 is completed, the upper end of the adjustable supporting rod 25 is propped against the lower end surface of the L-shaped integral steel core mold 22 and supports the L-shaped integral steel core mold 22; and a connecting plate 26 is arranged between two adjacent L-shaped core model steel frameworks 24 to ensure that the angle and levelness of the core mould meet the construction requirements.

(4) Placing steel reinforcement framework and threading prestressed steel hinge line

The method comprises the steps of integrally lifting and placing a bound pi beam steel rib frame 2 in a core mold, arranging finish rolling threads on a movable beam 8, arranging a plurality of jacks 7 between the movable beam 8 and a fixed beam 5, wherein one ends of the jacks 7 are fixedly arranged on jack butt joint plates 13 on beam splitting plates 6, the other ends of the jacks are connected with the movable beam 8, uniformly installing prestressed steel strands 3 according to designed intervals, sequentially penetrating the fixed ends of the prestressed steel strands 3 through counterforce walls 4 at one ends, the fixed beam 5 and steel strand penetrating holes 12 on the beam splitting plates 6, anchoring, sequentially penetrating the movable ends of the prestressed steel strands 3 through the counterforce walls 4 at the other ends, the fixed beam 5 and the steel strand penetrating holes 12 on the beam splitting plates 6, and then connecting the finish rolling threads, wherein the prestressed steel strands 3 penetrate through the core mold, and the finish rolling threads on the movable beam 8 are connected with the prestressed steel strands 3 through wire rod connectors, and the wire rod connectors are provided with external threads matched with the finish rolling threads.

(5) Tensioning prestressed tendon

The prestressed steel strand 3 is integrally tensioned by a jack 7 and integrally released, and the tensioning procedure is as follows: and (3) initially stretching by adopting a small-tonnage jack 7 to reach 20% sigma con, integrally stretching to design control stress by adopting a large-tonnage jack 7 for 5min, and anchoring the prestressed steel strand 3 by an anchor nut after the stretching control stress is in a stable state. Here σcon represents the tension control stress.

(6) Side die and end die are installed

The jacking 27 is supported on two sides of a core mould on the girder preparation pedestal 14, side moulds 28 are installed on the jacking 27, the side moulds 28 are longitudinally assembled in a through way, adjacent side moulds 28 are connected in a jogged way by adopting grooves 30 and protrusions 31, end plates 32 are inserted into slots 33 of two side moulds 28 corresponding to the end parts, and opposite side moulds 28 are provided with opposite pull connecting rods 29, so that the girder plate width is ensured.

(7) Pouring concrete

The concrete funnel 38, the door-type vertical frame 36 and the blanking pump pipe 39 are assembled into a whole in a factory in advance, the travelling wheel 35 is arranged at the lower end of the door-type vertical frame 36, the travelling wheel 35 is pushed to the upper part of the core mold, concrete is poured into the concrete funnel 38, the plurality of blanking pump pipes 39 are utilized to uniformly distribute the concrete into the core mold, the pi beam concrete 34 is longitudinally segmented and horizontally layered, the casting height of each layer is not more than 30cm, and the order of firstly webs and then top plates is pushed from one end to the other end; the prestressed steel strand 3 is embedded in concrete.

(8) Steel core mould heating maintenance

The resistance coil 23 on the L-shaped integral steel core mould 22 is electrified and the L-shaped integral steel core mould 22 is heated, the top surface of pi beam concrete 34 is covered by geotextile, and the water-retaining maintenance is sprayed.

(9) Form removal and tension releasing prestressed tendons

When the strength of the pi beam concrete 34 reaches 2.5Mpa, loosening the opposite-pull connecting rod 29, and sequentially removing the end plate 32 and the side die 28; and after the strength of the pi beam concrete 34 reaches 90% of the design strength and the concrete age is not less than 7 days, firstly loosening an anchor nut from the tensioning end of the prestressed steel strand 3, releasing the prestressed steel strand 3, and cutting off the prestressed steel strand 3 by adopting a grinding wheel cutting machine after the releasing is finished.

(10) Moving beam and beam plate storage

And (3) lifting and transporting the pi beams to a beam storage area by adopting a gantry crane, stacking the pi beams on the sleeper by pi Liang Fang for 2 layers, and supporting the pi beams between the two layers by using square timber.

Claims (7)

1. The construction method of the concrete precast pi-shaped beam is characterized by comprising the following specific steps of:

Step one, binding pi beam steel rib frames:

Manufacturing a pi beam steel bar jig frame (1) in a factory in advance according to the design size, wherein the pi beam steel bar jig frame (1) is of a pi structure, and binding the pi beam steel bar jig frame (2) in the pi beam steel bar jig frame (1);

Step two, construction of a counterforce wall: a plurality of steel pipe piles (20) are arranged on a foundation (21) according to the designed position, steel bars are bound on the tops of the steel pipe piles (20), forms counter-force walls (4) by formwork erection and concrete pouring on the outer sides of the steel bars, beam-making pedestal (14) are poured between the counter-force walls (4) at the two ends, a fixed beam (5) is arranged on the back of each counter-force wall (4), a beam splitting plate (6) is arranged on each fixed beam (5), a plurality of steel hinge penetrating holes (12) and jack butt joint plates (13) are arranged on each beam splitting plate (6), concrete pouring is performed on the foundation (21) on the outer side of each fixed beam (5) at one end to form a sliding pedestal (11), sliding rails (10) are arranged on the tops of the sliding pedestals (11), pulleys (9) are arranged on the bottoms of the movable beams (8), and the pulleys (9) on the bottoms of the movable beams (8) are arranged on the sliding rails (10) on the tops of the sliding pedestals (11), so that the movable beams (8) can slide along the sliding rails (10) on the sliding pedestals (11);

step three, installing a core mold, a bottom mold and a brush isolating agent:

The mandrel comprises a bottom die (17), a steel hinge (18), an L-shaped integral steel mandrel (22) and an L-shaped mandrel model steel skeleton (24), wherein a spacer is brushed on the surface of the mandrel before installation, a resistance coil is wound on the outer side of the L-shaped integral steel mandrel (22), a plurality of fine adjustment jacks (15) are supported on a girder preparation pedestal (14), an adjusting plate (16) is laid on the top of each fine adjustment jack (15), the bottom die (17) is fixedly arranged on the adjusting plate (16), the L-shaped integral steel mandrel (22) is connected with the bottom die (17) through the steel hinge (18), and the L-shaped mandrel model steel skeleton (24) is arranged on the outer side of the L-shaped integral steel mandrel (22); an adjusting screw rod (19) is arranged on the adjusting plate (16), the lower end of the adjusting screw rod (19) is hinged with the adjusting plate (16), and the upper end of the adjusting screw rod (19) is hinged with the L-shaped core model steel skeleton (24); the angle of the L-shaped integral steel core mould (22) is adjusted through an adjusting screw rod (19), and a connecting plate (26) is arranged between two adjacent L-shaped core mould steel frameworks (24);

Fourthly, placing a steel reinforcement framework and penetrating a prestressed steel hinge line:

The method comprises the steps of integrally lifting a bound pi beam steel rib frame (2) into a core mold, arranging finish rolling threads on a movable cross beam (8), arranging a plurality of jacks (7) between the movable cross beam (8) and a fixed cross beam (5), fixedly arranging one ends of the jacks (7) on jack butt-joint plates (13) on beam splitting plates (6), connecting the other ends of the jacks with the movable cross beam (8), sequentially penetrating the fixed ends of prestressed steel hinge wires (3) through counterforce walls (4) at one ends, the fixed cross beam (5) and steel hinge wires on the beam splitting plates (6) into holes (12) for anchoring, sequentially penetrating the movable ends of the prestressed steel hinge wires (3) through the counterforce walls (4) at the other ends, the fixed cross beam (5) and the steel hinge wire penetrating holes (12) on the beam splitting plates (6) and then connecting the finish rolling threads, penetrating the prestressed steel hinge wires (3) from the core mold, and connecting the threads on the movable cross beam (8) with the prestressed steel hinge wires (3) through wire rod connectors;

Step five, tensioning the prestressed tendons:

The prestressed steel strand (3) is integrally tensioned and integrally put by a jack (7);

step six, installing side dies and end dies:

A jacking bracket (27) is supported on two sides of a core mould on a girder preparation pedestal (14), side moulds (28) are arranged on the jacking bracket (27), the side moulds (28) are longitudinally assembled in a through-length mode, end plates (32) are inserted into slots (33) of two side moulds (28) corresponding to the end parts, and opposite side moulds (28) are provided with opposite pull connecting rods (29);

step seven, pouring concrete:

The concrete funnel (38) is assembled into a whole with the door-shaped vertical frame (36) and the blanking pump pipes (39) in advance in a factory, the travelling wheels (35) are arranged at the lower ends of the door-shaped vertical frame (36), the travelling wheels (35) push the travelling wheels to the upper part of the core mold, concrete is poured into the concrete funnel (38), and the plurality of blanking pump pipes (39) are utilized to uniformly distribute materials into the core mold;

step eight, heating and curing the steel core die:

Electrifying a resistance coil (23) on the L-shaped integral steel core mould (22) and heating the L-shaped integral steel core mould (22), covering the top surface of pi beam concrete (34) by geotextile, and spraying, moisturizing and curing;

Step nine, removing the die and releasing the prestressed tendons:

When the strength of the pi beam concrete (34) reaches 2.5Mpa, loosening the opposite-pull connecting rod (29), and sequentially removing the end plate (32) and the side die (28); after the strength of pi beam concrete (34) reaches 90% of the design strength and the concrete age is not less than 7 days, firstly loosening an anchor nut from the tensioning end of the prestressed steel strand (3) and releasing the prestressed steel strand (3), and then cutting off the prestressed steel strand (3);

step ten, moving the beam and storing the beam plate:

And (5) lifting and transporting the pi beam to a beam storage area by adopting a gantry crane.

2. The method of constructing a concrete precast pi beam according to claim 1, wherein in step seven, in step three, an adjustable support bar (25) is mounted on an adjustment plate (16); after the angle adjustment of the L-shaped integral steel core mold (22) is completed, the upper end of the adjustable supporting rod (25) is propped against the lower end surface of the L-shaped integral steel core mold (22) and supports the L-shaped integral steel core mold (22).

3. The construction method of a concrete precast pi beam according to claim 1, wherein in step five, the tensioning procedure of the prestressed steel strand (3) is as follows: firstly, a jack (7) is adopted for primary stretching, after 20% sigma con is reached, the jack (7) is adopted for integrally stretching the prestress steel strand (3) to design control stress for 5min, and after the stretching control stress is in a stable state, the prestress steel strand (3) is anchored.

4. The construction method of the concrete precast pi-shaped beam according to claim 1, wherein in the sixth step, a groove (30) is formed at one end of the side mold (28), a protrusion (31) is formed at the other end of the side mold, the groove (30) is matched with the protrusion (31), and adjacent side molds (28) are connected in a jogged mode by the groove (30) and the protrusion (31).

5. The method of constructing a precast concrete pi beam as claimed in claim 1, wherein in step seven, pi beam concrete (34) is cast in longitudinal sections and horizontal layers, each layer having a casting height of not more than 30cm.

6. The method of constructing a concrete precast pi beam according to claim 1, wherein pi Liang Fang is stacked in 2 layers of pi beam slabs on a sleeper in step ten, and square timber support is used between two layers of pi beams.

7. A concrete precast pi beam constructed by the construction method of the concrete precast pi beam of any one of claims 1 to 6.