Pre-tensioning method prestressed beam prefabrication construction method

Abstract

The invention discloses a pre-tensioning method prestressed beam prefabrication construction method, which comprises the following steps of: fixing a pre-tensioning pedestal and pedestal upright posts, mounting an integral hydraulic opening and closing mold at one time, manufacturing a reinforcement cage by using a special jig frame, fixing the position of a broken line prestressed steel beam after the reinforcement cage is integrally hoisted into the mold, and then performing one-key intelligent tensioning. And finally, concrete is poured, and demolding is performed after intelligent steam curing. Compared with a traditional construction technology, the design of the fixed pre-tensioning pedestal and the single-column pedestal stand column is adopted, the area of a production site is effectively saved, the construction site is cleaner and more orderly, and the site utilization rate is increased; the integral hydraulic opening and closing die and the reasonable broken line steel strand bending device effectively reduce the workload and the operation time of template assembly and disassembly construction and prestress construction, improve the working efficiency, reduce the labor input, greatly improve the industrialization degree of the pre-tensioning method prestressed precast beam, have good economic benefits, scientific and technological benefits and social benefits, and are worthy of popularization and application. The method is worthy of popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of municipal highway bridge construction, and in particular relates to a prefabrication construction method of a prestressed beam using a pre-tensioning method. Background Art

[0002] The prestressed concrete T-beam with broken line prestressing is a new type of prestressed concrete beam that has been applied in bridge engineering in my country in recent years. It overcomes the disadvantage that the traditional prestressed concrete components with straight prestressed tendons cannot be applied to larger spans. It has the advantage of post-tensioned components that can change the linear shape of prestressed tendons, and can be applied to the construction of larger span concrete bridges. At the same time, the traditional prestressed construction method is difficult to accurately control the prestressed tendons during the tensioning process, which easily causes prestress loss or uneven distribution, affecting the performance of the T-beam. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a prefabrication construction method of prestressed beams by pretensioning method to solve the deficiencies in the prior art.

[0004] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0005] A prefabrication construction method for prestressed beams using a pre-tensioning method is provided, comprising the following steps:

[0006] S1. Install an integral hydraulic opening and closing mold with a bottom template on the fixed pre-tensioning pedestal according to the requirements of the design drawings, and prepare steel strands, connectors, prestressed tendon bending bogies and intelligent tensioning equipment of corresponding specifications;

[0007] S2. According to the specifications and positions of the prestressed tendons in the design drawings, mark the starting point and inflection point of the fold line on the bottom template of the integral hydraulic opening and closing mold;

[0008] S3. Install prestressed steel strands in the steel cage, position the prestressed steel strands in layers, anchor the steel strands, and use intelligent tensioning equipment to tension and release the steel strands;

[0009] S4, initial prestressing to keep all steel strands in a straight state;

[0010] S5. Install a prestressed bending device at the starting point of the bending of the fold line steel strand, the prestressed bending device constrains the corresponding steel strand in the beam body at a set position, thereby forming a fold line shape that meets the design requirements;

[0011] S6, start the intelligent tensioning equipment, perform tensioning in the order of the folding line prestressing, and control the tensioning force until the tensioning force required by the design is reached;

[0012] S7, pouring concrete on the T-shaped beam so that the concrete fully wraps the steel strands;

[0013] S8. Perform intelligent steam curing on the cast T-beam;

[0014] S9. After the concrete strength of the T-beam reaches the design requirements, the prestressing is released and the beam is demoulded and transported.

[0015] As described in the prestressed beam prefabrication construction method, wherein the integral hydraulic opening and closing mold includes side formworks respectively arranged on both sides of the prestressed beam and a moving device for driving the side formworks to move vertically and horizontally.

[0016] As described in the prestressed beam prefabrication construction method, wherein the moving device includes a first jack, a motor and longitudinal and transverse tracks, and the motor drives the hydraulic rod of the first jack to push the side formwork to move along the longitudinal and transverse tracks.

[0017] As described in the prestressed beam prefabrication construction method using the pre-tensioning method, wherein the intelligent tensioning equipment includes a pedestal column and a tensioning beam base arranged on the fixed pre-tensioning pedestal, the pedestal column supports a second jack, and the tensioning beam base is provided with a tensioning beam, the tensioning beam is connected to the pedestal column by a plurality of force transmission rods, one end of the force transmission rod passes through the pedestal column and is connected to the tensioning beam, and the other end is connected to the second jack, after the steel strand is anchored to the tensioning beam, the tensioning and releasing of the steel strand is achieved by the extension and contraction of the piston of the second jack.

[0018] As described in the prestressed beam prefabrication construction method using the pre-tensioning method, wherein the steel cage in step S3 is an integrally hoistable steel cage, which is formed by tying the bottom web steel cage and the top plate steel cage on a special frame.

[0019] As described in the prefabrication construction method of prestressed beams by pretensioning method, when pouring concrete on the T-beam in step S7, the pouring is carried out in sections.

[0020] The beneficial effects of the technical solution of the present invention are:

[0021] 1. The integrated hydraulic opening and closing mold system is adopted, which has the function of automatic opening and closing of the template, which can improve the construction efficiency and quality;

[0022] 2. The zigzag prestressing design is adopted, and the tensioning force is controlled by intelligent tensioning equipment, which realizes the zigzag prestressing treatment of the prestressed steel strands, which can better adapt to the complex structural form of the bridge, make the force of the T-beam more reasonable, and improve the effect of prestressing and the bearing capacity of the T-beam;

[0023] 3. Equipped with intelligent tensioning equipment, it can perform tensioning according to design requirements, ensuring accurate application of prestress, improving the stability and safety of the structure. By accurately controlling the tensioning process, it can reduce prestress loss, make the prestress distribution more uniform, and further improve the performance of the T-beam;

[0024] 4. The prestressed bending device can constrain the steel strands at the set position, forming a broken line shape that meets the design requirements, ensuring the accuracy and reliability of the prestressing treatment;

[0025] 5. The steel cage adopts an integral hoistable structure, which is convenient for operation and installation at the construction site, and improves the construction efficiency and quality;

[0026] 6. The use of intelligent steam curing technology can effectively improve the strength and durability of concrete and ensure the performance of T-beams;

[0027] 7. Through advanced pressure anchor assembly technology, precise positioning of the bending and reliable anchoring of the prestressed steel strands are achieved, ensuring the effective application of prestressing treatment.

[0028] In summary, the present invention adopts the design of fixed pre-stressed pedestal and single-column pedestal column, which effectively saves production site area, makes the construction site more tidy and orderly, and improves site utilization rate; the integral hydraulic opening and closing mold and the reasonable folding line steel strand bending device effectively reduce the workload and operation time of template assembly and disassembly construction and prestressed construction, improve work efficiency, reduce labor input, greatly improve the industrialization degree of pre-stressed prefabricated beams by pre-stressing method, have good economic benefits, scientific and technological benefits and social benefits, and are worthy of promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To further illustrate the above-mentioned objectives, structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0030] Figure 1 This is an axonometric view of an integral hydraulic opening and closing mold of a preferred embodiment of the present invention;

[0031] Figure 2 This is a schematic structural diagram of a prestressed bending device according to a preferred embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of the intelligent tensioning equipment in a preferred embodiment of the present invention;

[0033] In the figure: 0, bottom formwork; 1, fixed pre-tensioning pedestal; 2, side formwork; 3, longitudinal and transverse tracks; 4, upper pressure anchor; 5, longitudinal steel; 6, middle pressure anchor; 7, lower pressure anchor; 8, pressure anchor limit block; 9, pedestal column; 10, tensioning beam base; 11, second jack; 12, tensioning beam; 13, force transmission rod; 14, steel strand bogie; 15, prestressed bending device. DETAILED DESCRIPTION

[0034] The terms "invention", "present invention" and "the present invention" used in this specification are intended to refer broadly to all subject matter of this specification and any patent claims below. Statements containing these terms should not be understood to limit the subject matter described herein or to limit the meaning or scope of any patent claim below. In addition, this specification does not attempt to describe or limit the subject matter covered by any claim of any specific component, paragraph, statement or figure of this application. The subject matter should be understood with reference to the entire specification, all drawings and any claims below. The present invention may have other embodiments and be practiced or implemented in other ways. Moreover, it should be understood that the words and terms used herein are for illustrative purposes and should not be considered as limiting.

[0035] The details of the present invention will now be discussed with reference to the accompanying drawings which illustrate the present invention by way of example only. In the accompanying drawings, similar features or components may be marked with the same reference numerals.

[0036] The use of "including," "having," and "comprising" and variations thereof herein is meant to encompass the items listed thereafter and their equivalents and additional items. Although reference may be made to directions such as above, below, upward, downward, rearward, bottom, top, front, rear, etc., in describing the drawings, for convenience, reference is made relative to the drawings. These directions are not intended to literally accept or limit the present invention in any form. In addition, terms such as "first," "second," "third," etc., are used herein for illustrative purposes and are not intended to indicate or imply importance or significance.

[0037] The prefabrication construction method of prestressed beams by pre-tensioning method of the present invention comprises the following steps:

[0038] S1. According to the requirements of the design drawings, install an integral hydraulic opening and closing mold with a bottom template 0 on the fixed pre-tensioning pedestal 1, and prepare steel strands, connectors, prestressed tendon bending bogies and intelligent tensioning equipment of corresponding specifications. Figure 1 As shown, the integral hydraulic opening and closing mold includes side molds 2 respectively arranged on both sides of the prestressed beam and a moving device for driving the side molds 2 to move vertically and horizontally. The longitudinal free combination of the molds is achieved by sliding the side mold system, and the hydraulic molds on both sides open and close simultaneously.

[0039] Furthermore, the moving device includes a first jack, a motor and longitudinal and transverse tracks 3. The motor drives the hydraulic rod of the first jack to push the side template 2 to move horizontally and vertically along the longitudinal and transverse tracks 3. The horizontal movement realizes automatic opening and closing of the template, and the longitudinal movement can transfer the side template 2 to another longitudinal production line.

[0040] S2. According to the specifications and positions of the prestressed tendons in the design drawings, mark the starting point and inflection point of the fold line on the bottom template 0 of the integral hydraulic opening and closing mold.

[0041] S3. Install the prestressed steel strands in the steel cage, position the prestressed steel strands in layers, anchor the steel strands, and use intelligent tensioning equipment to tension and release the steel strands. The steel cage is preferably an integrally hoistable steel cage, which is formed by tying the bottom web steel cage and the top plate steel cage on a special tire frame. The tensioning reaction system at both ends of the integral hydraulic opening and closing mold is an assembled steel structure, and the conversion of the anchoring position of the prestressed tendons can be achieved by selecting different steel components to meet different prestressing tensioning requirements. Install a steel strand diverter outside the beam body on the outside of the end mold.

[0042] S4. Initial prestressing makes all steel strands remain straight under stress.

[0043] S5. Install a prestressed bending device 15 at the starting point of the fold line steel strand bending. The prestressed bending device 15 constrains the corresponding steel strands in the beam body to a set position, thereby forming a fold line shape that meets the design requirements.

[0044] The prestressed bending device 15 consists of a disposable part embedded in the concrete of the beam body and a reusable part connected to the pedestal. The disposable part of the bending device embedded in the beam body is also called a split combined pressure anchor, which is formed in one step by casting and is divided into three types: upper anchor, middle anchor and lower anchor according to the installation relationship. Each pressure anchor is provided with three steel strand limit grooves, and the limit grooves are equipped with friction-reducing pads to reduce the friction between the steel strands and the pressure anchor during the tensioning stage. Each pressure anchor is provided with two rows of through holes along the height direction. The reusable part connected to the pedestal is composed of a steel section, a reaction crankshaft, a crankshaft seat and a bushing pre-embedded in the pedestal foundation, which is used to withstand the upward pulling force generated by the bending of the broken line steel bundle. When installing the reaction crankshaft, attention should be paid to the working direction, and limit devices should be set on both sides to prevent the crankshaft from flipping over. In this embodiment, combined with Figure 2As shown, first, the pressure anchors are placed in turn at the bent positions of each layer of steel strands, with one limit groove corresponding to one steel strand; two pull-down steel strands with a length of not less than 3.6m and provided with a P anchor (1.4m away from the upper end of the steel strand) are passed through the two rows of through holes of these pressure anchors from top to bottom, and the upper ends of the pull-down steel strands are pressed on the top locking position of the upper pressure anchor 4 by the P anchor, and the lower ends are connected to the reaction crankshaft (located below the longitudinal steel section 5) through the clip-type anchor. At this time, there is still a certain gap between each pressure anchor; a front card jack is used to pre-tighten each pull-down steel strand under the reaction crankshaft, and each pull-down steel strand is pre-tightened and a tensile force of about 60 to 70KN is continued to be applied, thereby eliminating the gaps between the upper pressure anchor 4, the medium pressure anchor 6, and the lower pressure anchor 7, and finally forming a whole. When the bottom of the lower pressure anchor 7 contacts the pressure anchor limit block 8 pre-installed on the bottom template 0, the whole set of pressure anchors is locked in the set position, the bending positioning of the fold line prestressed steel strand is also completed, and the line shape of the bent steel strand is initially formed.

[0045] For the preferred embodiment of the prestressed bending device, please refer to the relevant content in the patent CN209521080U previously applied for by the relevant applicant in this case.

[0046] Two PVC pipes are installed on the top of the upper pressure anchor 2 as a reserved channel for removing the pull-down steel strand before prestressing is released. The reserved channel is finally closed by grouting.

[0047] S6. Start the intelligent tensioning equipment, tension according to the order of the folding line prestressing, and control the tensioning force until the tensioning force required by the design is reached. Figure 3 As shown, the intelligent tensioning equipment includes a pedestal column 9 and a tensioning beam base 10 arranged on a fixed pre-tensioning pedestal 1, and a second jack 11 is supported on the pedestal column 9. The tensioning process adopts two-end tensioning, one end of which is installed with a 350t jack as the active end, and the other end as the passive end. A tensioning beam 12 is arranged on the tensioning beam base 10, and the tensioning beam 12 is connected to the pedestal column 9 through a number of force transmission rods 13. A group of four reserved holes (30-meter T-beam special pedestal, 8 reserved holes for general pedestal) are arranged on each pedestal column 9, and four force transmission rods 13 with a diameter of 80mm are respectively passed through the reserved holes, and trapezoidal threads are processed at both ends of the rods for assembling high-strength nuts. There is another high-strength nut and gasket near the outside of the middle section of the pedestal column 9, which can be tightened and loosened through the operating window on the through-hole jack base, and is used to lock the position of the force transmission rod 13 after the tensioning process is completed to maintain the tensioning force.

[0048] One end of the force transmission rod 13 passes through the pedestal column 9 and is connected to the tensioning beam 12, and the other end is connected to the second jack 11. During construction, the steel strand is anchored to the tensioning beam 12, and the tensioning and release of the steel strand is achieved through the extension and retraction of the pistons of four YCW350A-350 type second jacks 11.

[0049] The tensioning crossbeam 12 is provided with a steering shaft and a steering wheel. According to the arrangement of the broken line steel strand, the steel strand bogie 14 of the T-beam is provided with seven rows of steering shafts, and each row of steering shafts is provided with three steering wheels. The steering wheels are made of anti-friction materials and have a certain rigidity. They can be flexibly rotated on the steering shafts to reduce the friction resistance during the tensioning movement of the steel strand. The steel strand bogie 14 is installed between the two mold positions and is composed of a chassis, a steering shaft, a steering wheel, etc. The arrangement of the steering shaft and the steering wheel is the same as that of the tensioning crossbeam 12.

[0050] S7, pouring concrete on the T-shaped beam so that the concrete fully wraps the steel strands. When pouring concrete on the T-shaped beam, it is preferably done in sections.

[0051] S8. Carry out intelligent steam curing on the cast T-beams.

[0052] S9. After the concrete strength of the T-beam reaches the design requirements, the prestressing is released and the beam is demoulded and transported.

[0053] This implementation case adopts the "fixed pre-tensioning pedestal 1 + integral hydraulic mold + intelligent steam curing" process. The component production workshop is equipped with a 3.5m wide longitudinal passage, which is mainly used for the passage of steel cages and component finished product transportation platforms. Specifically, a total of 6 pre-tensioning production lines are built in the production workshop, with 2 longitudinal lines and 3 transverse lines. Each production line is 75m long and 3m wide, and 2 production pedestals can be arranged in series. The entire production workshop has a total of 12 production mold positions. According to the production rhythm of 3 days under steam curing conditions, the production capacity can reach 4 finished beams per day. The force transmission rods 13, tensioning beam base 10, tensioning beam 12, and steel strand bogie 14 at both ends of the production line are assembled steel structures. The side template 2 in the hydraulic mold system can move horizontally and vertically along the track. The horizontal movement realizes the automatic opening and closing of the template, and the longitudinal movement can transfer the side template 2 to another longitudinal production line. In this way, the two longitudinally arranged production lines can share 2 sets of side molds, and only 6 sets of side molds are needed to meet daily production.

[0054] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A prefabrication construction method for prestressed beams by pretensioning method, characterized in that: The following steps are involved: S1. Install an integral hydraulic opening and closing mold with a bottom template on the fixed pre-tensioning pedestal according to the requirements of the design drawings, and prepare steel strands, connectors, prestressed tendon bending bogies and intelligent tensioning equipment of corresponding specifications; S2. According to the specifications and positions of the prestressed tendons in the design drawings, mark the starting point and inflection point of the fold line on the bottom template of the integral hydraulic opening and closing mold; S3. Install prestressed steel strands in the steel cage, position the prestressed steel strands in layers, anchor the steel strands, and use intelligent tensioning equipment to tension and release the steel strands; S4, initial prestressing to keep all steel strands in a straight state; S5. Install a prestressed bending device at the starting point of the bending of the fold line steel strand, the prestressed bending device constrains the corresponding steel strand in the beam body at a set position, thereby forming a fold line shape that meets the design requirements; S6, start the intelligent tensioning equipment, perform tensioning in the order of the folding line prestressing, and control the tensioning force until the tensioning force required by the design is reached; S7, pouring concrete on the T-shaped beam so that the concrete fully wraps the steel strands; S8. Perform intelligent steam curing on the T-beam after casting; S9. After the concrete strength of the T-beam reaches the design requirements, the prestressing is released and the beam is demoulded and transported.

2. The method for prefabrication of prestressed beams according to claim 1, characterized in that: The integral hydraulic opening and closing mold comprises side mold plates respectively arranged on both sides of the prestressed beam and a moving device for driving the side mold plates to move vertically and horizontally.

3. The prefabrication construction method of prestressed beams according to claim 2, characterized in that: The moving device includes a first jack, a motor and longitudinal and transverse tracks. The motor drives the hydraulic rod of the first jack to push the side template to move along the longitudinal and transverse tracks.

4. The method for prefabrication of prestressed beams according to claim 1, characterized in that: The intelligent tensioning equipment includes a pedestal column and a tensioning beam base arranged on the fixed pre-tensioning pedestal, the pedestal column supports a second jack, and the tensioning beam base is provided with a tensioning beam, the tensioning beam is connected to the pedestal column by a plurality of force transmission rods, one end of the force transmission rod passes through the pedestal column and then connects to the tensioning beam, and the other end is connected to the second jack. After the steel strand is anchored to the tensioning beam, the tensioning and releasing of the steel strand is achieved by the extension and contraction of the piston of the second jack.

5. The method for prefabrication of prestressed beams according to claim 1, characterized in that: The steel cage in step S3 is an integrally hoistable steel cage, which is formed by tying a bottom web steel cage and a top plate steel cage on a special tire frame.

6. The method for prefabrication of prestressed beams according to claim 1, characterized in that: When pouring concrete on the T-beam in step S7, the pouring is carried out in sections.

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