Pre-tensioning method and device for quick tensioning and cutting-free construction of prestressed tendons

Abstract

The present invention relates to a method and device for the rapid pulling and releasing of prestressed tendons without cutting by the pre-tensioning method, comprising a front seat, a rear seat, a template and a hydraulic jack. The pre-tensioning method prestressed tendons rapid pulling and releasing without cutting construction device also comprises a non-cutting steel strand, a front long steel box, a rear long steel box, a short steel box and a traction bite device. The method comprises the steps of completing the preparation of the non-cutting steel strand, the front long steel box, the rear long steel box, the short steel box and the traction bite device in a processing factory; installing the front and rear long steel boxes and the short steel box and the traction bite device; and tensioning construction. The present invention can solve the problem of prestress loss during the tensioning, anchoring and releasing of prestressed tendons, improves the quality of prestressing tendon tensioning construction, ensures the durability of the structure, saves labor and effort, has good safety, high efficiency, fast construction progress, and has the advantages of no cutting and no waste of steel strands.

Description

Technical Field

[0001] The invention relates to a cutting-free construction method and device for quickly tensioning and releasing prestressed steel bars by using a pre-tensioning method to prevent stress loss of prefabricated parts. Background Art

[0002] When using the pre-tensioning method to reinforce prestressed concrete components with steel strands, if the number of steel strands is small, the steel strands can be sheared, sawed or melted with an oxy-acetylene flame when they are released, and they should be cut near the middle of the production line, which will reduce the rebound compared to cutting near one end of the pedestal and facilitate demoulding. Then, the steel strands with excess length at both ends of the concrete component are cut off to obtain the finished prestressed concrete component. Obviously, cutting off the steel strands with excess length at both ends of the concrete component is not only labor-intensive, but also causes a huge waste of steel strands.

[0003] However, if there are a large number of steel strands in the concrete component, all the steel strands should be stretched at the same time. It is not allowed to use the method of stretching one strand at a time. Otherwise, the last few steel strands will be subjected to excessive stress and suddenly break, resulting in a sudden increase in the stress transfer length of the component or cracking of the component end. The simultaneous stretching method can be achieved by stretching the beam, which can be stretched with a jack or a sand box or wedge pre-set at the beam support.

[0004] For the production of long-line pedestals, when the prestressed tendons of the components are steel bars, a spring dynamometer is generally used to directly measure the tension of the steel wire, and the elongation value does not need to be checked. After the steel wire is tensioned and anchored, a wire dynamometer should be used to check the prestress value of the steel wire. The quality of tensioning and releasing the prestressed steel bars of the pre-tensioning method is more difficult to control. This is mainly reflected in the fact that during construction, the tensioning jack directly jacks the tensioning beam. When multiple prestressed tendons are tensioned at the same time, the initial stress should be adjusted in advance to make their stresses consistent with each other. After the prestressed tendons are tensioned, they are anchored and released with sand boxes or wedges. The wedge release device is suitable for situations where the tensioning force is not large. When the air humidity is high or it rains, the sand in the sand box is easily clogged and it is not easy to flow out after compaction for a long period of time. When the jack is released after tensioning, the gaps in the sand are compressed, which can easily cause prestress loss. The sand flowing out of the sand box affects the moving beam on the rear side. Regardless of whether the sand box or wedge is used for tensioning, each pedestal requires a moving beam with a large amount of steel, resulting in the tensioning effect not meeting the design and specification requirements, and the tensioning quality is difficult to guarantee. Summary of the invention

[0005] The purpose of the present invention is to design a prestressed tendon fast pulling and releasing cutting-free construction method and device by pre-tensioning method, which can solve the problem of prestress loss in the process of prestressed tendon tensioning, anchoring and releasing, improve the construction quality of prestressed tendon tensioning, ensure the durability of the structure, save labor and effort, have good safety, high efficiency, fast construction progress, and no cutting and waste of steel strands.

[0006] To this end, the present invention includes a front seat, a rear seat, a template and a hydraulic jack, and the prestressed tendon rapid pulling and releasing cutting-free construction device also includes a cutting-free steel strand, a front long steel box, a rear long steel box, a short steel box and a traction bite device.

[0007] The length of the non-cutting steel strand is the sum of the length of the non-cutting steel strand located in the prestressed concrete member after the prestress is applied and the length of the non-cutting steel strand located at the two end surfaces of the concrete member. The two ends of the non-cutting steel strand are provided with a biting convex portion for clamping with a biting clamp. The inner end surface of the biting convex portion is a plane perpendicular to the axial direction of the steel strand, and the plane diameter of the biting convex portion is greater than the outer diameter of the steel strand.

[0008] The front and rear long steel boxes and the two short steel boxes are movable, split and independent structures. The rear end faces of the two short steel boxes are supported on the supporting steel beam surfaces on both sides of the outer side of the rod slot hole at the lower end of the front seat. The rear ends of the front long steel box are respectively located at the front ends of the two short steel boxes distributed at an interval. A hydraulic jack is respectively provided between the front end faces of the two short steel boxes and the rear end faces of the corresponding front long steel boxes. The rear end of the rear long steel box is supported on the outer side of the rod slot hole at the lower end of the rear seat.

[0009] The front long steel box is composed of a box shell, an I-beam layer, a base, a lifting ear, an exit hole, an entry hole and a reinforcing steel plate. The cross-section of the front long steel box is a rectangular frame. Several layers of I-beam layer plates are arranged in the box shell at intervals from top to bottom. The four sides of each I-beam layer plate are fixed to the corresponding inner side wall of the box shell as a whole. A base is provided at the lower end of the box shell. A plurality of entry holes corresponding to the number of steel strands in the prefabricated part are arranged side by side at an interval in the middle of the rear end box shell of the front long steel box corresponding to the length of a rod slot hole at the lower end of the front seat. The space in the box shell corresponding to the entry holes is a rod space. A reinforcing steel plate is provided in the middle of the front end face of the box shell. The reinforcing steel plate is fixed to the middle of the front end face of the box shell by fixing bolts. Several exit holes are provided on the reinforcing steel plate and the corresponding front end face of the box shell corresponding to each entry hole, and a lifting ear is provided on the upper end face of the box shell.

[0010] The rear long steel box is composed of a box shell, an I-beam layer plate, a base, a lifting lug, an outlet hole, an inlet hole and a reinforcing steel plate.

[0011] The short steel box is composed of a box body, layered steel plates and lifting ears. The box body is a hollow rectangular shell. Several layers of layered steel plates are arranged in intervals up and down inside the box. The four sides of each layered steel plate are fixed to the corresponding inner wall of the box body as a whole. A lifting ear is provided in the middle of the upper end surface of the box body.

[0012] The length of the front long steel box or the rear long steel box is greater than the sum of the width of a rod slot hole at the lower end of the outer side of the pedestal and the width of the two short steel boxes.

[0013] The traction and biting device is composed of a traction rod, a clamp located at one end of the traction rod and an adjusting and fixing nut located at the other end of the traction rod. The traction rod is made of finely rolled threaded steel. A clamp is provided at one end of the traction rod corresponding to the biting convex portion of the cut-free steel strand. The outer peripheral wall of the other end of the traction rod is an external threaded portion. The adjusting and fixing nut is a T-shaped frustum. The middle part of the adjusting and fixing nut is an internal threaded screw hole threadedly connected to the external threaded portion of the traction rod. The outer side of the adjusting and fixing nut is a tightening hexagonal convex edge platform.

[0014] The traction rod end with a clamping clamp end is provided with an axle seat, the rear end of the fixed clamp body is fixed on the axle seat, the front end of the fixed clamp body extends axially toward the traction rod and folds vertically into the axis of the traction rod to form a clamping clamp end, and a semicircular groove is provided in the middle of the clamping clamp end, the rear end of the movable clamp body is hinged on the axle seat through a clamp shaft, the front end of the movable clamp body extends axially toward the traction rod and folds vertically into the axis of the traction rod to form a clamping clamp end, and a semicircular groove is provided in the middle of the clamping clamp end, and screw holes are correspondingly provided in the middle of the movable and fixed clamp bodies, one end of the clamp screw passes through the screw hole from the outside of the fixed clamp body and then passes out from the screw hole on the movable clamp body, a gasket and a butterfly nut are provided on the passing end of the clamp screw, and a spring is sleeved on the clamp screw between the fixed clamp body and the movable clamp body, and rotating the butterfly nut can clamp or open the movable and fixed clamp bodies.

[0015] The diameter of the semicircular groove in the middle of the biting clamp end is the same as the outer diameter of the non-cutting steel strand.

[0016] A method for fast tensioning and releasing prestressed tendons without cutting using the above-mentioned device is characterized by comprising the following steps:

[0017] (1) Complete the preparation of the non-cutting steel strand, the front long steel box, the rear long steel box, the short steel box and the traction bite device in the processing factory.

[0018] According to the designed length of the cut-free steel strands in the prestressed concrete components by the prestressing method, the length of each cut-free steel strand in each prestressed concrete component is cut to adapt to the length of each cut-free steel strand. The length of each cut-free steel strand is the sum of the length of the cut-free steel strand in the prestressed concrete component after prestressing and the length of the cut-free steel strand designed to be located at the two end surfaces of the concrete component. Engaging protrusions for clamping with biting pliers are prepared at both ends of each cut-free steel strand, and the cut-free steel strands with the same length and located in the same concrete component are classified and bundled with labels.

[0019] The length of the front and rear long steel boxes is determined by the width of the concrete member, and the structures of the front and rear long steel boxes are the same.

[0020] The prepared various types of cut-free steel strands, a front long steel box, a rear long steel box, two short steel boxes and a large number of traction and biting devices are transported to the prestressed concrete component factory at the construction site.

[0021] (2) Prepare front and back seats parallel to the width of each concrete component on both sides of the table of the prestressed concrete component factory at the construction site.

[0022] (3) On the surface of a concrete component, a precast formwork is set up according to the size of the prestressed concrete component, and the non-cutting steel strands corresponding to the concrete component are laid in the precast formwork. It should be ensured that the distance between the two ends of each non-cutting steel strand outside the two ends of the precast formwork after tensioning is the same.

[0023] (4) Install the rear long steel box: Use a crane to place the rear long steel box on the outer side of the rear seat corresponding to the prefabricated template on the concrete component table. The rear end of the rear long steel box is held on the lower end of the outer side of the rear seat. The entry holes at the rear end of the rear long steel box are aligned with the corresponding non-cutting steel strands in the prefabricated template. Take the traction bite device corresponding to the number of non-cutting steel strands in the concrete component, remove the adjustment and fixing nut at the rear end of each traction rod, pass the rear end of each traction rod through the corresponding rod slot at the lower end of the rear seat, and pass through the entry hole at the rear end of the rear long steel box into the rod space in the box shell, and pass through the corresponding exit hole to the front of the rear long steel box. The ends are located outside the reinforcing steel plate and are then screwed with the adjusting and fixing nut parts respectively. The rear end of each adjusting and fixing nut part is located in the corresponding through-hole. The T-shaped frustum body at the front end of each adjusting and fixing nut part is stuck outside the reinforcing steel plate. The biting clamp at the front end of the traction rod is clamped and bitten on the biting bulge of the corresponding non-cutting steel strand end. The disc nut of the biting clamp is rotated to close the movable and fixed clamp bodies. The biting bulge of the non-cutting steel strand end is located at the inner end of the biting clamp end of the fixed and movable clamp bodies. The inner end of the biting clamp end of the fixed and movable clamp bodies holds the inner plane of the biting bulge, and the corresponding non-cutting steel strand end passes through the circular groove in the middle of the biting clamp end.

[0024] Rotate each T-shaped frustum to move the adjusting and fixing nut on the traction rod, and adjust the length of the corresponding end of the uniform non-cutting steel strand end extension prefabricated part template.

[0025] (5) Install the front long steel box and the two short steel boxes: hold the rear end faces of the two short steel boxes against the supporting steel beam surfaces on both sides of the outer side of the rod slot hole at the lower end of the front seat. The rear ends of the front long steel box are respectively located at the front ends of the two short steel boxes distributed at an interval. A hydraulic jack is respectively provided between the front end faces of the two short steel boxes and the rear end faces of the corresponding front long steel boxes, so that the ejection rods of each hydraulic jack can be ejected at the same distance.

[0026] The insertion holes at the rear end of the front long steel box are respectively aligned with the corresponding ends of the non-cut steel strands in the prefabricated part template, and the traction bite device corresponding to the number of the non-cut steel strands in the concrete member is taken, and the fixed and movable clamp bodies of each traction bite device are engaged with the corresponding engagement protrusions of the non-cut steel strand ends by the method of step (4). The rear end of each traction rod passes through the corresponding rod slot hole at the lower end of the front seat, enters from the insertion hole at the rear end of the front long steel box, and passes out from the corresponding exit hole. The front end of the front long steel box is located outside the reinforcing steel plate, and then is screwed with the adjusting and fixing nut parts respectively. The rear end of each adjusting and fixing nut part is located in the corresponding exit hole, and the T-shaped frustum body at the front end of each adjusting and fixing nut part is stuck outside the reinforcing steel plate. The traction rod extending at the rear side of the T-shaped frustum body is the traction end.

[0027] (6) Tensioning construction: First, use a small jack to apply 10% prestress to each non-cut steel strand at the traction end on the rear side of the T-shaped cone at the end of the front long steel box, and then tighten the adjustment nuts to fix the non-cut steel strands after stress, so that each steel strand is stressed uniformly; then, start two hydraulic jacks simultaneously to press the two sides of the rear end surface of the front long steel box, hold the front long steel box forward synchronously, and tension each non-cut steel strand to the controlled stress. The tensioning operation is carried out in accordance with the specifications. After the tensioning is completed, concrete is poured into the prefabricated formwork to cure the concrete. When the concrete reaches more than 75% of the design strength, the two hydraulic jacks are retracted simultaneously to complete the tensioning and remove the traction and biting device of the non-cut steel strand.

[0028] (7) Move the hydraulic jack, front long steel box, rear long steel box, short steel box and traction engaging device to the next platform for tensioning operation, and repeat steps (3) to (7) until the concrete component is completed.

[0029] The length of the front and rear long steel boxes is the sum of the width of the concrete component and the length of the two short steel boxes.

[0030] The support between the rear end of the rear long steel box and the lower end of the outer side of the rear seat, the support between the rear end faces of the two short steel boxes and the supporting steel beam surfaces on both sides of the outer side of the rod slot hole at the lower end of the front seat, and the support between the hydraulic jack and the front end faces of the two short steel boxes and the corresponding rear end faces of the front long steel boxes are all gapless supports.

[0031] The above device and method achieve the purpose of the present invention.

[0032] The present invention solves the problem of prestress loss during the process of prestressed tendon tensioning, anchoring and releasing, improves the construction quality of prestressed tendon tensioning, ensures structural durability, saves labor and effort, has good safety, high efficiency, fast construction progress, and no cutting of steel strands is required and no waste is caused.

[0033] Compared with the prior art, the present invention has the following advantages and positive effects:

[0034] (1) Compared with the traditional tensioning, anchoring and releasing operations, the present invention has high safety performance, small weight and convenient use. It solves the problem of retraction in the tensioning and anchoring stage, avoids the loss of prestressing, reduces the number of mobile steel boxes, avoids the retraction and even overturning of anchoring caused by construction personnel and workers' misoperation in the post-tensioning anchoring stage, and enhances the construction quality of prestressing, anchoring and releasing to ensure the durability of the structure. This machine can be applied to the prestressing construction of various structures with high efficiency and can speed up the progress of engineering construction.

[0035] (2) The present invention adopts cut-free steel strands, and uses standardized factory production instead of on-site trimming and cutting, which greatly speeds up the construction speed, eliminates the waste of steel strands, and saves steel. Calculations show that the present invention can save 20% of steel, reduce construction costs by 40%, and increase construction speed by more than 3 times.

[0036] (3) The present invention adopts a traction biting device that can quickly and conveniently bit and separate the ends of the steel strands without cutting, and eliminates traditional tensioning anchors, docking parts, etc., thereby improving work efficiency and quality and reducing construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the present invention.

[0038] Figure 2 It is a structural schematic diagram of the cut-free steel stranded wire of the present invention.

[0039] Figure 3 It is a front side structural schematic diagram of the front long steel box of the present invention.

[0040] Figure 4 It is a side structural schematic diagram of the front long steel box of the present invention.

[0041] Figure 5 It is a structural schematic diagram of the short steel box of the present invention.

[0042] Figure 6 It is a structural schematic diagram of the traction and biting device of the present invention. DETAILED DESCRIPTION

[0043] like Figures 1 to 6 As shown, a prestressed tendon fast pulling and releasing cutting-free construction device for prestressed tendons by pretensioning method includes a front seat, a rear seat, a template and a hydraulic jack; the prestressed tendon fast pulling and releasing cutting-free construction device for prestressed tendons by pretensioning method also includes a cutting-free steel strand 11, a front long steel box 3, a rear long steel box 301, a short steel box 4 and a traction bite device.

[0044] like Figure 2As shown, the length of the non-cutting steel strand 11 is the sum of the length of the non-cutting steel strand located in the prestressed concrete member after the prestress is applied and the length of the non-cutting steel strand located at the two end faces of the concrete member. The length of the non-cutting steel strand designed to be extended refers to the length of the non-cutting steel strand reserved for the two end faces of the concrete member when the two end faces of the concrete member are firmly butted according to the design requirements. The two ends of the non-cutting steel strand are provided with a biting protrusion 14 for clamping with a biting clamp.

[0045] The inner end surface of the bite convex part is a plane perpendicular to the axial direction of the steel strand, and the plane diameter of the bite convex part is larger than the outer diameter of the steel strand. The cut-free steel strand and the bite convex part are completed at the processing factory after shearing, and then the two ends of the cut-free steel strand are completed by traditional processes such as pressing and melting. The two ends of the cut-free steel strand are provided with bite convex parts for clamping by the bite pliers.

[0046] like Figure 1 , Figures 3 to 5 As shown, the structure of the front long steel box 3 is the same as that of the rear long steel box 301, so only the structure of the front long steel box is described. The front and rear long steel boxes and the two short steel boxes are movable split independent structures.

[0047] The rear end faces of the two short steel boxes are supported on the supporting steel beam 7 on both sides of the outer side of the rod slot 16 at the lower end of the front seat 15. The two ends of the rear side of the front long steel box are respectively located at the front ends of the two short steel boxes distributed at a distance. A hydraulic jack 6 is respectively arranged between the front end faces of the two short steel boxes and the rear end faces of the corresponding front long steel boxes, that is, the rear end of the hydraulic jack is supported on the front end faces of the short steel boxes, and the ejection rod 5 of the hydraulic jack is supported on both sides of the rear end faces of the corresponding front long steel boxes. The rear end of the rear long steel box is supported on the outer side of the rod slot at the lower end of the rear seat 8.

[0048] like Figure 3 to Figure 4 As shown, the front long steel box 3 is composed of a box shell 35, an I-beam layer plate 31, a base 37, a lifting lug 36, a through hole 33, an inlet hole 331 and a reinforcing steel plate 34. The cross section of the front long steel box is a rectangular frame, and several layers of I-beam layers are arranged in the box shell at intervals. The four sides of each I-beam layer plate are fixed to the corresponding inner side wall of the box shell by welding. The thickness of the I-beam layer plate is 2.5 to 3 cm. A base is provided at the lower end of the box shell for supporting the box shell. Corresponding to the length of a rod slot hole 16 at the lower end of the front seat, a plurality of through holes 331 corresponding to the number of steel strands in the prefabricated part are arranged side by side at intervals in the middle of the rear end box shell, and the space in the box shell corresponding to the through hole is a rod space 38. A reinforcing steel plate 34 is provided in the middle of the front end face of the box shell, and the reinforcing steel plate is fixed to the middle of the front end face of the box shell by fixing bolts 32. A plurality of through holes 33 are provided on the reinforcing steel plate and the corresponding front end face of the box shell corresponding to each through hole. A lifting lug is provided on the upper end face of the box shell to facilitate the movement of the front long steel box.

[0049] The rear long steel box 301 has the same structure as the front long steel box, and the rear long steel box is composed of a box shell, an I-beam layer plate, a base, lifting ears, an outlet hole, an inlet hole and a reinforcing steel plate.

[0050] The length of the front long steel box or the rear long steel box is greater than the sum of the width of a rod slot hole at the lower end of the outer side of the pedestal and the width of the two short steel boxes.

[0051] like Figure 5 As shown, the short steel box 4 is composed of a box body 42, layered steel plates 43 and lifting ears 41. The box body is a hollow rectangular shell, and several layers of layered steel plates are arranged in intervals in the upper and lower parts of the box body. The four sides of each layered steel plate are fixed to the corresponding inner wall of the box body by welding. A lifting ear is provided in the middle of the upper end surface of the box body to facilitate the movement of the short steel box.

[0052] like Figure 6 As shown, the traction and biting device is composed of a traction rod 1, a biting clamp 9 located at one end of the traction rod and an adjusting and fixing nut 2 located at the other end of the traction rod. The traction rod is made of finely rolled threaded steel. A biting clamp is provided at one end of the traction rod corresponding to the biting convex part of the cut-free steel strand, and the outer peripheral wall of the other end of the traction rod is an external threaded part 131. The adjusting and fixing nut is a T-shaped frustum, and the middle part of the adjusting and fixing nut is an internal threaded screw hole 211 that is screwed to the external threaded part of the traction rod. The outer side of the adjusting and fixing nut is a tightening hexagonal convex platform 21, so as to facilitate the use of pliers to rotate the adjusting and fixing nut to shorten or lengthen the length of the traction rod end, that is, to adjust the distance from the traction rod to the outside of the through-hole after the biting clamp clamps the biting convex part corresponding to the cut-free steel strand. The rear diameter of the adjusting and fixing nut is smaller than the through-hole, and the outer circumference of the front T-shaped frustum is larger than the outer circumference of the through-hole.

[0053] The traction rod end provided with the clamp end is provided with an axle seat 99, the rear end of the fixed clamp body 91 is fixed on the axle seat, the front end of the fixed clamp body extends axially toward the traction rod and folds vertically into the axis of the traction rod to form a clamp end 93, and a semicircular groove 910 is provided in the middle of the clamp end. The rear end of the movable clamp body 98 is hinged on the axle seat through the clamp shaft 97, the front end of the movable clamp body extends axially toward the traction rod and folds vertically into the axis of the traction rod to form a clamp end, and a semicircular groove is provided in the middle of the clamp end. The diameter of the semicircular groove in the middle of the clamp end is the same as the outer diameter of the cut-free steel strand.

[0054] The middle of the movable and fixed caliper bodies are provided with screw holes, one end of the clamp screw 92 passes through the screw hole from the outside of the fixed caliper body and then passes out from the screw hole on the movable caliper body, and a gasket 95 and a butterfly nut 95 are provided on the end of the clamp screw. A spring 96 is sleeved on the clamp screw between the fixed caliper body and the movable caliper body, and the movable and fixed caliper bodies can be clamped or opened by turning the butterfly nut.

[0055] A method for quickly pulling and releasing prestressed tendons without cutting using a prestressed tendon quick pulling and releasing construction device without cutting for prestressed tendons, comprising the following steps:

[0056] (1) Complete the preparation of the non-cutting steel strand, the front long steel box, the rear long steel box, the short steel box and the traction bite device in the processing factory.

[0057] According to the designed length of the non-cut steel strands in the prestressed concrete components, cut the length of each non-cut steel strand in each prestressed concrete component. The length of each non-cut steel strand is the sum of the length of the non-cut steel strand in the prestressed concrete component after the prestress is applied and the length of the non-cut steel strand designed to be located at the two end surfaces of the concrete component. Prepare bite convex parts for clamping with bite clamps at both ends of each non-cut steel strand. Classify and bundle the non-cut steel strands of the same length and located in the same concrete component;

[0058] The length of the front and rear long steel boxes is determined by the width of the concrete member, and the structures of the front and rear long steel boxes are the same.

[0059] The prepared various types of cut-free steel strands, a front long steel box, a rear long steel box, two short steel boxes and a large number of traction and biting devices are transported to the prestressed concrete component factory at the construction site.

[0060] like Figure 1 As shown, (2) front and rear seats parallel to the width of each concrete component are prepared on both sides of the table 17 of the prestressed concrete component factory at the construction site. The lower ends of the front and rear seats are provided with rod slots 16 corresponding to the distribution width of the cut-free steel strands of the concrete component.

[0061] (3) A precast formwork 10 is set up on a concrete member surface according to the size of the prestressed concrete member. The precast formwork contains a pouring space 12 for the prestressed concrete member. Each non-cutting steel strand corresponding to the concrete member is laid out in the precast formwork. It should be ensured that the distance between the two ends of each non-cutting steel strand outside the two ends of the precast formwork is the same after being tensioned.

[0062] (4) Install the rear long steel box 301: Use a crane to place the rear long steel box on the outside of the rear seat corresponding to the prefabricated template on the concrete component table. The rear end of the rear long steel box is supported on the lower end of the outer side of the rear seat. The entry holes at the rear end of the rear long steel box are aligned with the corresponding non-cutting steel strands in the prefabricated template. Take the traction bite device corresponding to the number of non-cutting steel strands in the concrete component, remove the adjustment fixing nut at the rear end of each traction rod, pass the rear end of each traction rod through the corresponding rod slot at the lower end of the rear seat, pass through the entry hole at the rear end of the rear long steel box into the rod space in the box shell, and pass through the corresponding exit hole. The front end of the rear long steel box is located outside the reinforcing steel plate, and then screwed with the adjustment fixing nut respectively. The rear end of each adjustment fixing nut is located in the corresponding exit hole 33, and the T-shaped frustum 21 at the front end of each adjustment fixing nut is stuck outside the reinforcing steel plate.

[0063] The biting clamps at the front end of each traction rod are clamped and bitten on the biting convex parts of the corresponding non-cutting steel strand ends. The disc nuts of the biting clamps are turned to close the movable and fixed clamp bodies. The biting convex parts of the non-cutting steel strand ends are located at the inner ends of the biting clamp ends of the fixed and movable clamp bodies. The inner ends of the biting clamp ends of the fixed and movable clamp bodies hold the inner plane of the biting convex parts of the non-cutting steel strands at this end. The other end of the corresponding non-cutting steel strand passes through the circular groove in the middle of the biting clamp end, and then passes through the corresponding side prefabricated formwork, the pouring space of the concrete component, and passes through the other side prefabricated formwork, and is located outside the other side prefabricated formwork.

[0064] Rotate each T-shaped frustum to move the adjusting and fixing nut on the traction rod, and adjust the length of the corresponding end of the uniform non-cutting steel strand end extension prefabricated part template.

[0065] (5) Install the front long steel box and the two short steel boxes: The rear end faces of the two short steel boxes 4 are supported on the supporting steel beams 7 on both sides of the outer side of the rod slot hole at the lower end of the front seat. The rear ends of the front long steel box 3 are respectively located at the front ends of the two short steel boxes distributed at a distance. A hydraulic jack 6 is respectively arranged between the front end faces of the two short steel boxes and the rear end faces of the corresponding front long steel boxes, so that the ejection rods 5 of each hydraulic jack are ejected by the same distance.

[0066] Each entry hole at the rear end of the front long steel box is aligned with each non-cutting steel strand at the corresponding end in the prefabricated template. A traction bite device corresponding to the number of non-cutting steel strands in the concrete member is taken, and the fixed and movable clamp bodies of each traction bite device are engaged with the corresponding engagement convex part of the non-cutting steel strand end by the method of step (4). The rear end of each traction rod passes through the corresponding rod slot at the lower end of the front seat, enters from the entry hole at the rear end of the front long steel box, and passes out from the corresponding exit hole. The front end of the front long steel box is located outside the reinforcing steel plate, and then is screwed with the adjusting fixing nut parts respectively. The rear end of each adjusting fixing nut part is located in the corresponding exit hole. The T-shaped cone body at the front end of each adjusting fixing nut part is stuck outside the reinforcing steel plate. The traction rod extending at the rear side of the T-shaped cone body is the traction end 13.

[0067] (6) Tensioning construction: First, use a small jack to apply 10% prestress to each non-cutting steel strand at the traction end 13 on the rear side of the T-shaped cone body at the end of the front long steel box, and then tighten the adjustment nuts to fix the non-cutting steel strands after stress, so that each steel strand is stressed uniformly; then start two hydraulic jacks to press the two sides of the rear end surface of the front long steel box, hold the front long steel box forward synchronously, and tension each non-cutting steel strand to the controlled stress. The tensioning operation is carried out in accordance with the specifications. After the tensioning is completed, concrete is poured into the prefabricated formwork to cure the concrete. When the concrete reaches more than 75% of the design strength, the two hydraulic jacks are retracted synchronously to complete the tensioning and remove the traction and biting device of the non-cutting steel strand.

[0068] (7) Move the hydraulic jack, front long steel box, rear long steel box, short steel box and traction engaging device to the next platform for tensioning operation, and repeat steps (3) to (7) until the concrete component is completed.

[0069] The length of the front and rear long steel boxes is the sum of the width of the concrete component and the length of the two short steel boxes.

[0070] The support between the rear end of the rear long steel box and the lower end of the outer side of the rear seat, the support between the rear end faces of the two short steel boxes and the supporting steel beam surfaces on both sides of the outer side of the rod slot hole at the lower end of the front seat, and the support between the hydraulic jack and the front end faces of the two short steel boxes and the corresponding rear end faces of the front long steel boxes are all gapless supports.

[0071] In short, the present invention can solve the problem of prestress loss during the tensioning, anchoring and releasing of prestressed tendons, improve the quality of prestressed tendon tensioning construction, ensure structural durability, save labor and effort, have good safety, high efficiency, fast construction progress, and no cutting and waste of steel strands. It can be promoted for use.

Claims

1. A pre-tensioning method prestressed tendon rapid pulling and releasing without cutting construction device, comprising a front seat, a back seat, a prefabricated part template and a hydraulic jack, characterized in that: The prestressed tendon quick pulling and releasing cutting-free construction device for pre-tensioning method also includes cutting-free steel strand, front long steel box, rear long steel box, short steel box and traction bite device; The length of the cut-free steel strand is the sum of the length of the cut-free steel strand located in the prestressed concrete member after prestressing and the length of the cut-free steel strand located on the outer side of the two end surfaces of the concrete member. The two ends of the cut-free steel strand are provided with biting protrusions for clamping with biting pliers; the inner end surface of the biting protrusion is a plane perpendicular to the axial direction of the steel strand, and the plane diameter of the biting protrusion is larger than the outer diameter of the steel strand; the front and rear long steel boxes and the two short steel boxes are movable split independent structures, and the rear end surfaces of the two short steel boxes are supported on the supporting steel beam surfaces on both sides of the outer side of the rod slot hole at the lower end of the front seat, and the rear ends of the front long steel box are respectively located at a distance apart. The front ends of the two short steel boxes are distributed, and a hydraulic jack is respectively arranged between the front end faces of the two short steel boxes and the rear end faces of the corresponding front long steel boxes. The rear end of the rear long steel box is supported on the outside of the rod slot hole at the lower end of the rear seat; the front long steel box is composed of a box shell, an I-beam layer plate, a base, a lifting ear, an exit hole, an entry hole and a reinforcing steel plate. The cross section of the front long steel box is a rectangular frame. Several layers of I-beam layer plates are arranged in the box shell at intervals up and down. The four peripheries of each I-beam layer plate are respectively fixed to the corresponding inner side walls of the box shell as a whole. A base is arranged at the lower end of the box shell, and the rear end box shell of the front long steel box corresponding to the length of the rod slot hole at the lower end of the front seat A number of insertion holes corresponding to the number of steel strands in the prefabricated part are arranged side by side at intervals in the middle of the body, and the space inside the box shell corresponding to the insertion holes is a rod space, and a reinforcing steel plate is provided in the middle of the front end surface of the box shell, and the reinforcing steel plate is fixed to the middle of the front end surface of the box shell by fixing bolts, and a number of exit holes are provided on the reinforcing steel plate and the corresponding front end surface of the box shell corresponding to each entry hole, and a lifting lug is provided on the upper end surface of the box shell; the rear long steel box is composed of a box shell, an I-beam layer plate, a base, a lifting lug, an exit hole, an entry hole and a reinforcing steel plate; the short steel box is composed of a box body, a layered steel plate and a lifting lug, and the box body is a hollow rectangular shell, and several layers of layered steel The plates are arranged in the box body at intervals up and down, and the four sides of each layered steel plate are fixed to the corresponding inner wall of the box body as a whole, and a lifting ear is provided in the middle of the upper end surface of the box body; the traction and biting device is composed of a traction rod, a biting clamp located at one end of the traction rod and an adjustment and fixing nut located at the other end of the traction rod. The traction rod is made of finely rolled threaded steel, and a biting clamp is provided at one end of the traction rod corresponding to the biting convex part of the free-cut steel strand. The outer peripheral wall of the other end of the traction rod is an external threaded part, and the adjustment and fixing nut is a T-shaped truncated cone body. The middle part of the adjustment and fixing nut is an internal threaded screw hole screwed with the external threaded part of the traction rod, and the outer side of the adjustment and fixing nut is a fastening hexagonal convex edge platform; The traction rod end provided with the biting clamp end is provided with an axle seat, the rear end of the fixed clamp body is fixed on the axle seat, the front end of the fixed clamp body extends axially toward the traction rod and folds vertically into the axis of the traction rod to form a biting clamp end, and a semicircular groove is provided in the middle of the biting clamp end, the rear end of the movable clamp body is hinged on the axle seat through the clamp shaft, the front end of the movable clamp body extends axially toward the traction rod and folds vertically into the axis of the traction rod to form a biting clamp end, and a semicircular groove is provided in the middle of the biting clamp end, and screw holes are correspondingly provided in the middle of the movable and fixed clamp bodies, one end of the clamp screw passes through the screw hole from the outside of the fixed clamp body and then passes through the screw hole on the movable clamp body, and the clamp screw passes through the screw hole. A gasket and a butterfly nut are provided on the output end, and a spring is sleeved on the clamp screw between the fixed clamp body and the movable clamp body. Turning the butterfly nut can clamp or open the movable and fixed clamp bodies; the rear end of each traction rod passes through the corresponding rod slot hole at the lower end of the front seat or the rear seat, and passes through the rod space in the box shell from the entry hole at the rear end of the corresponding front long steel box or the rear long steel box, and passes through the front long steel box or the rear long steel box from the corresponding exit hole. The front end is located outside the reinforced steel plate, and then screwed with the adjusting and fixing nut parts respectively. The rear end of each adjusting and fixing nut part is located in the corresponding exit hole, and the T-shaped frustum body at the front end of each adjusting and fixing nut part is stuck outside the reinforced steel plate.

2. The device according to claim 1, characterized in that: The length of the front long steel box or the rear long steel box is greater than the sum of the width of a rod slot hole at the lower end of the outer side of the pedestal and the width of the two short steel boxes.

3. The device according to claim 1, characterized in that: The diameter of the semicircular groove in the middle of the biting clamp end is the same as the outer diameter of the non-cutting steel strand.

4. A method for fast tensioning and releasing prestressed tendons without cutting using the device according to claim 1, characterized in that: The steps include: (1) Complete the preparation of the non-cutting steel strand, the front long steel box, the rear long steel box, the short steel box and the traction bite device in the processing factory; According to the designed length of the non-cut steel strands in the prestressed concrete member by the prestressing method, the length of each non-cut steel strand in each prestressed concrete member is cut to suit the length of each non-cut steel strand. The length of each non-cut steel strand is the sum of the length of the non-cut steel strand in the prestressed concrete member after the prestress is applied and the length of the non-cut steel strand designed to be located outside the two end surfaces of the concrete member. Engaging convex parts for clamping by the biting pliers are prepared at the two ends of each non-cut steel strand. The non-cut steel strands of the same length and located in the same concrete member are classified and bundled with labels; The length of the front and rear long steel boxes is determined by the width of the concrete member, and the structures of the front and rear long steel boxes are the same; Transport the prepared various types of non-cutting steel strands, a front long steel box, a rear long steel box, two short steel boxes and a number of traction and biting devices to the prestressed concrete component factory at the construction site; (2) Prepare front and back seats parallel to the width of each concrete component on both sides of the table of the prestressed concrete component factory at the construction site; (3) On the surface of a concrete component, a precast formwork is set up according to the size of the prestressed concrete component, and each non-cutting steel strand corresponding to the concrete component is laid in the precast formwork. It should be ensured that the distance between the two ends of each non-cutting steel strand outside the two ends of the precast formwork after tensioning is the same; (4) Install the rear long steel box: Use a crane to place the rear long steel box on the outer side of the rear seat corresponding to the prefabricated template on the concrete component table. The rear end of the rear long steel box is held on the lower end of the outer side of the rear seat. The entry holes at the rear end of the rear long steel box are aligned with the corresponding non-cutting steel strands in the prefabricated template. Take the traction bite device corresponding to the number of non-cutting steel strands in the concrete component, remove the adjustment and fixing nut at the rear end of each traction rod, pass the rear end of each traction rod through the corresponding rod slot at the lower end of the rear seat, and pass through the entry hole at the rear end of the rear long steel box into the rod space in the box shell, and pass through the corresponding exit hole to the front of the rear long steel box. The ends are located outside the reinforcing steel plate and are then respectively screwed with the adjusting and fixing nut parts. The rear end of each adjusting and fixing nut part is located in the corresponding through-hole. The T-shaped frustum body at the front end of each adjusting and fixing nut part is stuck outside the reinforcing steel plate. The biting clamp at the front end of the traction rod is clamped and bitten on the biting convex part of the corresponding non-cutting steel strand end. The disc nut of the biting clamp is rotated to close the movable and fixed clamp bodies. The biting convex part of the non-cutting steel strand end is located at the inner end of the biting clamp end of the fixed and movable clamp bodies. The inner end of the biting clamp end of the fixed and movable clamp bodies holds the inner side plane of the biting convex part, and the corresponding non-cutting steel strand end passes through the circular groove in the middle of the biting clamp end. Rotate each T-shaped frustum to move the adjusting fixing nut on the traction rod, and adjust the length of the corresponding end of the uniform non-cutting steel strand end extension prefabricated part template; (5) Install the front long steel box and the two short steel boxes: hold the rear end faces of the two short steel boxes against the supporting steel beam surfaces on both sides of the outer side of the rod slot hole at the lower end of the front seat. The rear ends of the front long steel box are respectively located at the front ends of the two short steel boxes distributed at a distance. A hydraulic jack is respectively arranged between the front end faces of the two short steel boxes and the rear end faces of the corresponding front long steel boxes, so that the ejection rods of each hydraulic jack have the same ejection length; Each entry hole at the rear end of the front long steel box is aligned with each non-cut steel strand at the corresponding end in the prefabricated template, and a traction bite device corresponding to the number of non-cut steel strands in the concrete member is taken, and the fixed and movable clamp bodies of each traction bite device are engaged with the corresponding engagement protrusions of the non-cut steel strand ends by the method of step (4), and the rear end of each traction rod passes through the corresponding rod slot hole at the lower end of the front seat, enters from the entry hole at the rear end of the front long steel box, and passes out from the corresponding exit hole. The front end of the front long steel box is located outside the reinforcing steel plate, and then is screwed with the adjusting and fixing nut parts respectively, the rear end of each adjusting and fixing nut part is located in the corresponding exit hole, the T-shaped frustum body at the front end of each adjusting and fixing nut part is stuck outside the reinforcing steel plate, and the traction rod extending at the rear side of the T-shaped frustum body is the traction end; (6) Tensioning construction: First, use a small jack to apply 10% prestress to each non-cutting steel strand at the traction end on the rear side of the T-shaped cone body at the end of the front long steel box, and then tighten the adjustment nuts to fix the non-cutting steel strands after stress, so that each steel strand is stressed uniformly; then, start two hydraulic jacks to press the two sides of the rear end surface of the front long steel box, hold the front long steel box forward synchronously, and tension each non-cutting steel strand to the controlled stress. The tensioning operation is carried out in accordance with the specifications. After the tensioning is completed, concrete is poured into the prefabricated formwork to cure the concrete. When the concrete reaches more than 75% of the design strength, the two hydraulic jacks are retracted synchronously to complete the tensioning, and the traction and biting device of the non-cutting steel strand is removed; (7) Move the hydraulic jack, front long steel box, rear long steel box, short steel box and traction engaging device to the next platform for tensioning operation, and repeat steps (3) to (7) until the concrete component is completed.

5. The method according to claim 4, characterized in that: The length of the front and rear long steel boxes is the sum of the width of the concrete component and the length of the two short steel boxes.

6. The method according to claim 4, characterized in that: The support between the rear end of the rear long steel box and the lower end of the outer side of the rear seat, the support between the rear end faces of the two short steel boxes and the supporting steel beam surfaces on both sides of the outer side of the rod slot hole at the lower end of the front seat, and the support between the hydraulic jack and the front end faces of the two short steel boxes and the corresponding rear end faces of the front long steel boxes are all gapless supports.

Images