Post-tensioning method prestressed beam tensioning equipment and method

Abstract

The invention relates to the technical field of building and municipal construction, in particular to post-tensioning method prestressed beam tensioning equipment and method.The post-tensioning method prestressed beam tensioning equipment is used for applying pre-tensioning stress to a steel strand extending in the first direction and comprises a telescopic part, and a plurality of sleeves sliding in the first direction are arranged on the telescopic part; each sleeve is arranged on one steel strand in a sleeving mode, a first clamping piece capable of enabling the sleeve and the steel strand to be relatively static is arranged between each sleeve and the corresponding steel strand, a first cavity and a plurality of second cavities with variable volumes are formed in the telescopic part, the first cavity is communicated with the second cavities, and the second cavities are communicated with the telescopic part. And the volume change of the second cavity can drive the sleeve to slide on the telescopic piece. When the first cavity is filled with hydraulic oil, the hydraulic oil in the first cavity enters the multiple second cavities, the sleeves can drive the corresponding steel strands to be straightened through the change of the pressure intensity in the second cavities, and when the pressure intensity in the second cavities is consistent, the straightening degrees of the multiple steel strands are consistent, and pre-tightening is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of building and municipal construction, and particularly to a tensioning device and method for a post-tensioned prestressed beam. Background Art

[0002] Prestress tensioning is to apply tension in advance to a component, so that the prestressed tensioned component bears compressive stress, and then causes it to undergo a certain deformation to cope with the loads acting on the structure itself, including the loads of the component's own weight, wind load, snow load, earthquake load, etc. Generally, steel strands, jacks, anchor plates, and wedge grips are used for tensioning.

[0003] Before an engineering structure component bears an external load, pre-tensile stress is applied to the steel strands in the tensioned module to improve the bending resistance and stiffness of the component, delay the time when cracks appear, and increase the durability of the component. When specifically applied in the construction field, the stored pre-applied pressure, when the component bears the tension generated by the external load, first offsets the pre-pressure in the tensile zone of the concrete, and then as the load increases, the concrete is only subjected to tension, which limits the elongation of the concrete and delays or prevents cracks from appearing. In the prior art, during the operation of tensioning steel strands, a jack is used to tension multiple steel strands. Although the operation efficiency can be improved, it is impossible to perform one-to-one operations on each steel strand, and it is easy to cause the problem that the applied force does not meet the standard due to differences in the installation position and angle of the steel strands. Summary of the Invention

[0004] Based on this, in view of the problem that the applied force on each steel strand of the current tensioning device is likely to be inconsistent, it is necessary to provide a tensioning device and method for a post-tensioned prestressed beam.

[0005] The above object is achieved by the following technical solutions: A post-tensioning prestressed beam tensioning device is used to apply pre-tension stress to multiple steel strands extending along a first direction on a box girder. It includes a pre-tightening mechanism, a tensioning mechanism, and a positioning mechanism. The pre-tightening mechanism includes a telescopic member. The box girder and the telescopic member are arranged along the first direction. A first chamber is provided inside the telescopic member. Multiple steel strands penetrate the telescopic member along the first direction and are slidably connected to the telescopic member. A sleeve that slides along the first direction is sleeved on each steel strand. The sleeve is slidably arranged on the telescopic member, and a second chamber with a variable volume is provided between each sleeve and the telescopic member. The second chamber is communicated with the first chamber, and hydraulic oil is filled in the first chamber and the second chamber. When hydraulic oil is filled into the second chamber through the first chamber, the hydraulic oil can push the sleeve away from the box girder. A first clamping piece is provided between each sleeve and the corresponding steel strand to enable the sleeve and the steel strand to be relatively stationary in the first direction. The tensioning mechanism is arranged between the box girder and the telescopic member and can control the reduction of the volume of the first chamber and tension the multiple steel strands when the sleeve and the corresponding steel strand are relatively stationary. The positioning mechanism is used to clamp and position the multiple tensioned steel strands.

[0006] Preferably, the tensioning mechanism includes a hydraulic cylinder, a mounting plate, and a first power group. The hydraulic cylinder is arranged between the box girder and the telescopic member. The mounting plate is arranged on the hydraulic cylinder. Multiple first through holes that penetrate the mounting plate along the first direction are provided on the mounting plate. Each steel strand penetrates the mounting plate and is located in one of the first through holes. A second clamping piece and a first wedge block are provided in each first through hole. The second clamping piece is slidably arranged on the mounting plate along the radial direction of the corresponding steel strand, and the second clamping piece slides and abuts against the steel strand. The first wedge block is movably arranged on the mounting plate to control the magnitude of the abutting force between the second clamping piece and the steel strand. The first power group is used to provide power for the movement of the first wedge block.

[0007] Preferably, the first power group includes a first push cylinder. The first push cylinder is slidably arranged on the telescopic member along the first direction. The first push cylinder is located on the side of the first wedge block away from the box girder and is slidably connected to the first wedge block. A third chamber containing hydraulic oil and with a variable volume is provided between the first push cylinder and the telescopic member. The sliding of the first push cylinder on the telescopic member can change the volume of the third chamber. The telescopic member expands and contracts along the first direction. When the telescopic member elongates or shortens, the volume of the first chamber decreases or increases. A flow channel is provided inside the telescopic member. The flow channel is communicated with the first chamber and the third chamber respectively, and a pressure valve is provided in the flow channel.

[0008] Preferably, the positioning mechanism includes an anchor backing plate, an anchor barrel, a second power group, and a positioning component. The anchor backing plate is arranged on the box girder. A plurality of second through holes penetrating the anchor barrel in the first direction are formed in the anchor barrel. A plurality of steel strands penetrate the anchor barrel and are respectively located in one of the second through holes. A third gripper and a second wedge block are arranged in each second through hole. The third gripper is slidably arranged on the anchor barrel along the radial direction of the corresponding steel strand, and the third gripper slides to abut against the steel strand. The second wedge block is movably arranged on the anchor barrel for controlling the magnitude of the abutting force between the third gripper and the steel strand. The second power group provides power for the movement of the second wedge block; the positioning component is used for limiting the third gripper abutting against the steel strand.

[0009] Preferably, a grouting port is formed in the anchor backing plate.

[0010] Preferably, each of the first gripper, the second gripper, and the third gripper includes a plurality of arc plates. When the projections of the plurality of arc plates in the first direction are concentric, there is a spacing between two adjacent arc plates around the first direction.

[0011] Preferably, spiral grooves opposite to the helix direction of the steel strand are arranged on the surfaces of the arc plates of the first gripper, the second gripper, and the third gripper close to the corresponding steel strands.

[0012] Preferably, the number of the positioning components is the same as the number of the second through holes. Each positioning component is correspondingly arranged in one of the second through holes. Each positioning component includes a clamping block. The number of the clamping blocks is the same as that of the arc plates in the third gripper. The plurality of clamping blocks are arranged around the circumference of the steel strand in the corresponding second through hole. The clamping blocks are slidably arranged on the anchor barrel along the radial direction of the steel strand. An elastic piece for driving the clamping blocks to approach the steel strand is arranged between each clamping block and the anchor barrel. The clamping blocks are clamped with the third gripper in the first direction.

[0013] Preferably, lifting lugs are arranged on the hydraulic cylinder.

[0014] An embodiment of the present invention further provides a tensioning method for a post-tensioned prestressed beam, including the following steps: S1, placing the steel strands into the prefabricated box girder and passing the steel strands through the sleeves on the expansion members.

[0015] S2, connecting the sleeves and the steel strands together using the first gripper.

[0016] S3, filling hydraulic oil into the first chamber until the pressures in the plurality of second chambers are the same, completing the pre-tightening of the steel strands.

[0017] S4, starting the tensioning mechanism to tension the pre-tightened steel strands.

[0018] S5, starting the positioning mechanism to position the tensioned steel strands.

[0019] The beneficial effects of the present invention are as follows: A first chamber and a plurality of second chambers which are communicated are arranged on the telescopic member. When hydraulic oil is filled into the first chamber, the hydraulic oil in the first chamber enters into the plurality of second chambers, so that the volume of the second chambers increases. At the same time, a plurality of sleeves drive the corresponding steel strands to be straightened along the first direction. If one of the steel strands is straightened first, the hydraulic oil in the first chamber will flow into other second chambers, so that the other sleeves continue to drive the corresponding steel strands to be straightened until all the steel strands in the same group are straightened. In this way, the pre-tightening of a plurality of steel strands in the same group is realized, ensuring that the forces on the plurality of steel strands in the same group are basically the same during tensioning. At the same time, the manual operation procedures are reduced, the automation degree is improved, and time and labor are saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of a post-tensioned prestressed beam tensioning device provided by an embodiment of the present invention; Figure 2 is a front view of a post-tensioned prestressed beam tensioning device provided by an embodiment of the present invention; Figure 3 is Figure 2 a sectional view taken along line A-A in Figure 4 is Figure 3 an enlarged view at B in Figure 5 is Figure 4 an enlarged view at C in Figure 6 is Figure 3 an enlarged view at D in Figure 7 is an exploded view of a positioning mechanism of a post-tensioned prestressed beam tensioning device provided by an embodiment of the present invention.

[0021] Wherein: 100, first chamber; 101, second chamber; 102, first clamping piece; 103, sleeve; 104, sliding cylinder; 105, pulling cylinder; 106, cylinder block; 107, guiding cylinder; 108, piston rod; 109, mounting plate; 110, first through hole; 111, second clamping piece; 112, first wedge block; 113, first pushing cylinder; 114, third chamber; 115, second through hole; 116, third clamping piece; 117, second wedge block; 118, fixed cylinder; 119, second pushing cylinder; 120, duct; 121, anchor backing plate; 122, anchor sleeve; 123, fourth chamber; 124, clamping block; 125, elastic piece; 126, receiving groove; 127, groove; 128, flow channel; 129, pressure valve; 200, box girder; 201, grouting port; 202, lifting lug; 203, steel strand. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] The serial numbers assigned to components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any sequential or technical meaning. The "connection" and "coupling" as used in the present invention, unless otherwise specified, both include direct and indirect connection (coupling). In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0024] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0025] Such as Figures 1 to 7As shown in the figure, an embodiment of the present invention provides a post-tensioning prestressed beam tensioning device for applying pre-tension stress to a plurality of steel strands 203 extending along a first direction on a box girder 200, including a pre-tightening mechanism, a tensioning mechanism, and a positioning mechanism. The pre-tightening mechanism includes a telescopic member. The box girder 200 and the telescopic member are arranged along the first direction, and a first chamber 100 is provided inside the telescopic member. The plurality of steel strands 203 are divided into multiple groups, and the number of steel strands 203 in each group is multiple. The multiple steel strands 203 in each group penetrate through the telescopic member along the first direction and are slidably connected to the telescopic member. A sleeve 103 that slides along the first direction is sleeved on each steel strand 203. The sleeve 103 is slidably arranged on the telescopic member, and a second chamber 101 with a variable volume is provided between each sleeve 103 and the telescopic member. The second chamber 101 communicates with the first chamber 100, and the first chamber 100 and the second chamber 101 are filled with hydraulic oil. When hydraulic oil is filled into the second chamber 101 through the first chamber 100, the hydraulic oil can push the sleeve 103 away from the box girder 200. A first clamping piece 102 that can make the sleeve 103 and the steel strand 203 relatively stationary in the first direction is provided between each sleeve 103 and the corresponding steel strand 203. The tensioning mechanism is arranged between the box girder 200 and the telescopic member, and can control the volume of the first chamber 100 to decrease when the sleeve 103 and the corresponding steel strand 203 are relatively stationary, and tension the multiple steel strands 203 in the same group; the positioning mechanism is used for clamping and positioning the multiple tensioned steel strands 203 in the same group.

[0026] Specifically, the number of the first clamping pieces 102 between each sleeve 103 and the corresponding steel strand 203 is multiple. The multiple first clamping pieces 102 are on the side of the sleeve 103 away from the box girder 200, and the multiple first clamping pieces 102 can enclose an annular cylinder that wraps the steel strand 203. When the multiple first clamping pieces 102 are in contact with the steel strand 203, there is a gap between two adjacent first clamping pieces 102. One end of the sleeve 103 close to the first clamping piece 102 is provided with an inclined surface, and the inclined surface gradually approaches the axis of the sleeve 103 from the end of the sleeve 103 to the direction close to the box girder 200. An inclined surface adapted to the sleeve 103 is provided on each first clamping piece 102. After the multiple first clamping pieces 102 are in contact with the steel strand 203, they can enter into the sleeve 103 and be slidably connected to the inclined surface on the sleeve 103. When the sleeve 103 gradually approaches the first clamping piece 102, a force in the radial direction of the sleeve 103 will be applied to the first clamping piece 102 through the inclined surface, so that the multiple first clamping pieces 102 squeeze the steel strand 203 and the friction force between the first clamping pieces 102 and the steel strand 203 increases. At the same time, the friction force between the first clamping piece 102 and the sleeve 103 will also gradually increase until the two no longer slide relative to each other.

[0027] The circumferential surface of the sleeve 103 is provided with a step, which slides in the second chamber 101, and the step is located on the side of the second chamber 101 away from the box girder 200. When the hydraulic oil in the second chamber 101 increases, the hydraulic oil can push the sleeve 103 away from the box girder 200 in the first direction through the step.

[0028] A first chamber 100 and a plurality of second chambers 101 which are communicated are arranged on the telescopic member. When filling hydraulic oil into the first chamber 100, the hydraulic oil in the first chamber 100 enters into the plurality of second chambers 101, so that the volume of the second chambers 101 increases, and at the same time, a plurality of sleeves 103 drive the corresponding steel strands 203 to be straightened along the first direction. If one of the steel strands 203 is straightened first, the hydraulic oil in the first chamber 100 will flow into other second chambers 101, so that the other sleeves 103 continue to drive the corresponding steel strands 203 to be straightened until all the steel strands 203 in the same group are straightened, thereby realizing the pre-tightening of the plurality of steel strands 203 in the same group, ensuring that the forces on the plurality of steel strands 203 in the same group are basically the same when tensioning, reducing the manual operation procedures at the same time, improving the automation degree, and saving time and effort.

[0029] In this embodiment, the tensioning mechanism includes a hydraulic cylinder, a mounting plate 109 and a first power group. The hydraulic cylinder is arranged between the box girder 200 and the telescopic member, the mounting plate 109 is arranged on the hydraulic cylinder, a plurality of first through holes 110 penetrating the mounting plate 109 along the first direction are arranged on the mounting plate 109, each steel strand 203 in the same group penetrates the mounting plate 109 and is located in one of the first through holes 110, a second clamping piece 111 and a first wedge block 112 are arranged in each first through hole 110, the second clamping piece 111 is slidably arranged on the mounting plate 109 along the radial direction of the corresponding steel strand 203, and the second clamping piece 111 slides to abut against the steel strand 203. The first wedge block 112 is movably arranged on the mounting plate 109 and is used for controlling the magnitude of the abutting force between the second clamping piece 111 and the steel strand 203, and the first power group is used for providing power for the movement of the first wedge block 112.

[0030] Specifically, the hydraulic cylinder includes a cylinder block 106, a guide cylinder 107, and a piston rod 108. The cylinder block 106 is disposed between the box girder 200 and the telescopic member. The guide cylinder 107 is disposed in the cylinder block 106 along a first direction, and one end of the guide cylinder 107 is connected to the cylinder block 106. One end of the piston rod 108 is disposed in the cylinder block 106 and sleeved on the guide cylinder 107, and the piston rod 108 is slidably connected to the guide cylinder 107. One end of the piston rod 108 located in the cylinder block 106 divides the cylinder block 106 into two mutually isolated oil chambers. The other end of the piston rod 108 penetrates the cylinder block 106 and is connected to the telescopic member. By alternately supplying oil to and pumping oil from the two oil chambers, the piston rod 108 slides relative to the cylinder block 106 in the first direction. The piston rod 108 that slides relative to the cylinder block 106 can drive the telescopic member to move or push the telescopic member to contract when the telescopic member no longer moves relative to the corresponding first clip 102 between the sleeve 103 and the corresponding first clip 102.

[0031] The second clip 111 and the first wedge 112 are sequentially away from the steel strand 203 along the radial direction of the steel strand 203. The first wedge 112 is slidably connected to the second clip 111 and the mounting plate 109 respectively. The contact surface between the first wedge 112 and the second clip 111 is parallel to the first direction. The first through hole 110 is a tapered hole. The large end of the first through hole 110 is closer to the telescopic member than its small end. The surface of the first wedge 112 in sliding contact with the mounting plate 109 is adapted to the tapered surface of the first through hole 110. The first power group controls the first wedge 112 to approach the mounting plate 109, which can make the first wedge 112 move along the first direction and the radial direction of the steel strand 203. The moving first wedge 112 drives the second clip 111 to abut against the steel strand 203 along the radial direction of the steel strand 203, so that the second clip 111 fixes the steel strand 203.

[0032] After multiple sleeves 103 drive the corresponding first clips 102 to pre-tighten the corresponding steel strands 203, the first power group can be used to push the first wedge 112 to make the second clip 111 abut against the corresponding steel strand 203. At this time, the steel strand 203 to be tensioned is located on the side of the second clip 111 away from the telescopic member. When the second clip 111 clamps the steel strand 203, the second clip 111 applies a force to the steel strand 203 from the radial direction of the steel strand 203, and will not change the position of the steel strand 203 in the first direction, so that the lengths of the steel strands 203 to be tensioned are the same, that is, during the tensioning process, the problem of insufficient force caused by inconsistent elongation of multiple steel strands 203 in the same group is effectively avoided.

[0033] In this embodiment, the first power group includes a first pushing cylinder 113. The first pushing cylinder 113 is slidably arranged on the telescopic member along the first direction. The first pushing cylinder 113 is located on the side of the first wedge block 112 away from the box girder 200 and is slidably connected to the first wedge block 112. A third chamber 114 containing hydraulic oil and having a variable volume is provided between the first pushing cylinder 113 and the telescopic member. The volume of the third chamber 114 can be changed by the sliding of the first pushing cylinder 113 on the telescopic member. The telescopic member expands and contracts along the first direction. When the telescopic member extends or contracts, the volume of the first chamber 100 decreases or increases. A flow channel 128 is provided in the telescopic member. The flow channel 128 is respectively communicated with the first chamber 100 and the third chamber 114, and a pressure valve 129 is provided in the flow channel 128.

[0034] Specifically, the telescopic member includes a sliding cylinder 104 and a pulling cylinder 105. One end of the sliding cylinder 104 is arranged on the end of the cylinder block 106 away from the box girder 200. The other end of the sliding cylinder 104 is slidably inserted into the pulling cylinder 105. The first chamber 100 and the second chamber 101 are located on the pulling cylinder 105. The third chamber 114 is located on the sliding cylinder 104. The flow channel 128 is provided on the sliding cylinder 104 and penetrates through one end of the sliding cylinder 104 close to the pulling cylinder 105.

[0035] The threshold value of the pressure valve 129 is greater than the oil pressure required for straightening multiple steel strands 203 in the same group. When the telescopic member contracts and the hydraulic oil in the first chamber 100 flows into the multiple second chambers 101, the volume of the second chamber 101 corresponding to the straightened steel strand 203 no longer changes. The hydraulic oil in the first chamber 100 will flow into the second chamber 101 corresponding to the unstraightened steel strand 203, so that all the steel strands 203 are straightened. At this time, the oil pressures in the first chamber 100 and the multiple second chambers 101 are equal. As the telescopic member continues to contract, after the oil pressure in the first chamber 100 increases and is greater than the threshold value of the pressure valve 129, the oil pressure in the first chamber 100 will flow into the third chamber 114, so that the second clamping piece 111 clamps the corresponding steel strand 203. Clamping and positioning the steel strand 203 after the steel strand 203 is tightened and does not undergo obvious deformation makes the force and elongation of the steel strand 203 as consistent as possible during subsequent tensioning, reducing errors.

[0036] In this embodiment, a plurality of ducts 120 for installing the same group of steel strands 203 are provided on the box girder 200. The positioning mechanism includes an anchor backing plate 121, an anchor barrel 122, a second power group, and a positioning component. The anchor backing plate 121 is arranged on the box girder 200 and located at the duct 120. A plurality of second through holes 115 penetrating through the anchor barrel 122 along the first direction are formed in the anchor barrel 122. A plurality of steel strands 203 in the same group penetrate through the anchor barrel 122 and are respectively located in one second through hole 115. A third wedge grip 116 and a second wedge 117 are arranged in each second through hole 115. The third wedge grip 116 is slidably arranged on the anchor barrel 122 along the radial direction of the corresponding steel strand 203 for controlling the magnitude of the abutting force between the third wedge grip 116 and the steel strand 203. The second power group provides power for the movement of the second wedge 117. The positioning component is used for limiting the third wedge grip 116 abutting against the steel strand 203.

[0037] Specifically, the third wedge grip 116 and the second wedge 117 are sequentially away from the steel strand 203 along the radial direction of the steel strand 203. The second wedge 117 is slidably connected to the third wedge grip 116 and the anchor barrel 122 respectively. The contact surface between the second wedge 117 and the third wedge grip 116 extends along the first direction. The second through hole 115 is a tapered hole. The large end of the second through hole 115 is closer to the telescopic member than its small end. The surface of the second wedge 117 in sliding contact with the anchor barrel 122 is adapted to the tapered surface of the second through hole 115. After the steel strand 203 is tensioned, the second power group controls the second wedge 117 to move along the first direction and the radial direction of the steel strand 203. The moving second wedge 117 drives the third wedge grip 116 to abut against the steel strand 203, so that the third wedge grip 116 fixes the tensioned steel strand 203.

[0038] The second power group includes a fixed barrel 118 and a second push barrel 119. The fixed barrel 118 is arranged on the cylinder block 106 and extends along the first direction. A plurality of steel strands 203 in the same group pass through the inside of the fixed barrel 118 and are slidably connected to the fixed barrel 118. The fixed barrel 118 is arranged between the anchor barrel 122 and the cylinder block 106. The fixed barrel 118 is sleeved on the anchor barrel 122, and the fixed barrel 118 is slidably connected to the anchor barrel 122 along the first direction and can abut in the first direction for positioning the cylinder block 106. The second push barrel 119 is slidably arranged on the fixed barrel 118 along the first direction, and the second push barrel 119 can slide to abut against the third wedge grip 116. A fourth chamber 123 with a variable volume is arranged between the second push barrel 119 and the fixed barrel 118. Hydraulic oil can also be added to the fourth chamber 123. The hydraulic oil can control the volume of the fourth chamber 123. The fourth chamber 123 is located on the side of the fixed barrel 118 away from the third wedge grip 116.

[0039] In this embodiment, a grouting port 201 is formed on the anchor backing plate 121. The anchor backing plate 121 and the anchor barrel 122 can block the duct 120 on the box girder 200, and the inside of the blocked duct 120 can be grouted through the grouting port 201.

[0040] In this embodiment, each of the first clamping pieces 102, the second clamping pieces 111, and the third clamping pieces 116 includes a plurality of arc plates. When the projections of the plurality of arc plates in the first direction are concentric, there is a gap between two adjacent arc plates around the first direction.

[0041] Specifically, when the plurality of arc plates in the first clamping piece 102, the second clamping piece 111, or the third clamping piece 116 are concentric, the plurality of arc plates can also approach each other. After approaching each other, the plurality of arc plates will no longer be concentric. When the plurality of arc plates clamp the steel strand 203, the steel strand 203 is not easily squeezed into the gap between two adjacent arc plates.

[0042] In this embodiment, spiral grooves opposite to the helix direction of the steel strand 203 are provided on the surfaces of the arc plates in the first clamping piece 102, the second clamping piece 111, and the third clamping piece 116 close to the corresponding steel strand 203. By providing the spiral grooves, the friction force between the second clamping piece 111 and the steel strand 203 can be increased, so that relative sliding between the second clamping piece 111 and the steel strand 203 is not likely to occur.

[0043] In this embodiment, the number of the positioning components is the same as the number of the second through holes 115. Each positioning component is correspondingly arranged in one of the second through holes 115. Each positioning component includes a clamping block 124. The number of the clamping blocks 124 is the same as the number of the arc plates in the third clamping piece 116. The plurality of clamping blocks 124 are arranged around the circumferential direction of the steel strand 203 in the corresponding second through hole 115. The clamping blocks 124 are slidably arranged on the anchor barrel 122 in the radial direction of the steel strand 203. An elastic piece 125 for driving the clamping block 124 to approach the steel strand 203 is provided between each clamping block 124 and the anchor barrel 122. The clamping block 124 is clamped with the third clamping piece 116 in the first direction.

[0044] Specifically, a plurality of sets of receiving grooves 126 are formed in the anchor barrel 122. The number of receiving grooves 126 in each set is multiple. The multiple receiving grooves 126 in the same set are arranged along the circumferential direction of the steel strand 203, and each receiving groove 126 communicates with the corresponding second through hole 115. Each clamping block 124 is slidably disposed in one of the receiving grooves 126, and the elastic piece 125 is located in the receiving groove 126. A groove 127 is formed on the surface of the second wedge block 117 away from the third clamping piece 116. Chamfers are provided on the clamping block 124 and the second wedge block 117. When the second wedge block 117 approaches the clamping block 124 and contacts the clamping block 124, the second wedge block 117 will push the clamping block 124 to slide in the receiving groove 126 and away from the steel strand 203 through the cooperation of the chamfers on itself and the clamping block 124. When the groove 127 on the second wedge block 117 moves to the middle between the clamping block 124 and the steel strand 203, the clamping block 124 will be inserted into the groove 127 under the action of the elastic piece 125, restricting the sliding of the second wedge block 117 in the first direction.

[0045] The surface of the clamping block 124 close to the box girder 200 is an inclined surface. The inclined surface on the clamping block 124 gradually approaches the box girder 200 from the side close to the steel strand 203 to the side away from the steel strand 203. An inclined surface adapted to the inclined surface on the clamping block 124 is provided in the groove 127. After the clamping block 124 and the groove 127 are matched, it will have the effect of a barb, which can increase the stability of the clamping connection between the clamping block 124 and the second wedge block 117.

[0046] In this embodiment, a lifting lug 202 is provided on the hydraulic cylinder. The hydraulic cylinder can be lifted through the lifting lug 202, reducing the manual labor intensity and being able to better maintain the position of the hydraulic cylinder at the same time.

[0047] Specifically, an oil injection device is provided outside the cylinder block 106. The oil injection device can inject oil or extract oil into the first chamber 100, the two oil chambers in the cylinder block 106, and the fourth chamber 123.

[0048] The working principle of the post-tensioned prestressed beam tensioning device provided by the above embodiment is as follows: First, the steel strand 203 is passed through the box girder 200, then the anchor backing plate 121 is passed through the steel strand 203 and installed on the box girder 200. Then, the anchor barrel 122 is installed on the anchor backing plate 121. Then, the steel strand 203 is sequentially passed through the fixed cylinder 118, the guiding cylinder 107, the piston rod 108, the sliding cylinder 104, and the sleeve 103 along the first direction.

[0049] Then, push the cylinder block 106 closer to the box girder 200. Before the cylinder block 106 drives the fixed cylinder 118 to move and contact the anchor barrel 122, place the third clamping piece 116 into the second through hole 115. Then, push the cylinder block 106 so that the fixed cylinder 118 is sleeved on the anchor barrel 122 and abuts against the anchor barrel 122. At this time, the second push cylinder 119 abuts against the third clamping piece 116, making the position of the third clamping piece 116 relatively stable. Then, place the first clamping piece 102 into the sleeve 103 and make the second chamber 101 in a smaller state. The sleeve 103 is connected to the steel strand 203 through the first clamping piece 102, and there is friction between them. Then, inject oil into the first chamber 100 through the oil injection device. When the first chamber 100 expands or the hydraulic oil in the first chamber 100 flows into the second chamber 101, the expansion of the first chamber 100 will cause the pulling cylinder 105 to move away from the sliding cylinder 104, thereby driving the steel strand 203 to slide through the sleeve 103 and the first clamping piece 102. Or the hydraulic oil flowing into the second chamber 101 will push the sleeve 103 to move away from the sliding cylinder 104 along the first direction, and the sleeve 103 drives the steel strand 203 to slide through the first clamping piece 102. When one of the steel strands 203 is straightened, it indicates that the tensile force on this steel strand 203 is greater than that on the unstraightened steel strands 203. The hydraulic oil in the first chamber 100 will flow into the other second chambers 101, making the unstraightened steel strands 203 straightened.

[0050] After all the steel strands 203 are straightened, the pressure in each second chamber 101 is the same. At this time, continue to inject hydraulic oil into the first chamber 100, and the pressure in the first chamber 100 and the second chambers 101 increases. When the pressure in the first chamber 100 increases to exceed the threshold of the pressure valve 129, the pressure valve 129 opens, and the hydraulic oil in the first chamber 100 enters the flow channel 128 through the pressure valve 129, and then enters the third chamber 114. The hydraulic oil entering the third chamber 114 pushes the first push cylinder 113 closer to the box girder 200. The first push cylinder 113 drives the first wedge block 112 to move synchronously. At the same time, the first wedge block 112 approaches the steel strand 203 along the radial direction of the steel strand 203 under the guidance of the first through hole 110. The first push cylinder 113 and the first wedge block 112 slide relative to each other. The first wedge block 112 approaching the steel strand 203 pushes the second clamping piece 111 to abut against the steel strand 203. As the hydraulic oil in the first chamber 100 increases, the clamping force of the second clamping piece 111 on the steel strand 203 increases.

[0051] Then, maintain the oil pressure in the first chamber 100 and inject oil into one of the oil chambers in the cylinder block 106 through the oil injection device, so that the piston rod 108 moves away from the box girder 200 relative to the cylinder block 106. The piston rod 108 drives the telescopic member and the second clamping piece 111 to move, and the second clamping piece 111 clamps the steel strand 203 to move, and the steel strand 203 is stretched.

[0052] After the steel strand 203 is stretched, hydraulic oil is filled into the fourth chamber 123 through an oil injection device. The increase in the hydraulic oil in the fourth chamber 123 causes the second push cylinder 119 to slide relative to the fixed cylinder 118 towards the box girder 200. The second push cylinder 119 pushes the second wedge block 117 to slide on the anchor cylinder 122. Under the guidance of the conical surface of the second through hole 115, the second wedge block 117 pushes the third clamping piece 116 towards the steel strand 203, and the third clamping piece 116 clamps the steel strand 203 along the radial direction of the steel strand 203. When the second wedge block 117 slides in the first direction towards the box girder 200, the second wedge block 117 will contact the clamping block 124. At the same time, under the cooperation of the inclined surfaces of the second wedge block 117 and the clamping block 124, the second wedge block 117 will push the clamping block 124 to move away from the steel strand 203 in the receiving groove 126. The clamping block 124 pushes the elastic piece 125 to deform, and the elastic piece 125 starts to store energy. When the groove 127 on the second wedge block 117 moves to the middle between the clamping block 124 and the third clamping piece 116, the clamping block 124 slides out of the receiving groove 126 and into the groove 127 under the action of the elastic piece 125. At this time, the second wedge block 117 no longer moves in the second direction, and the third clamping piece 116 also clamps the steel strand 203.

[0053] Next, the hydraulic oil in the first chamber 100 is extracted through the oil injection device. The hydraulic oil in the first chamber 100 decreases, and the volume of the first chamber 100 also decreases. The telescopic member contracts and drives the sleeve 103 to move relative to the steel strand 203. The sleeve 103 is separated from the first clamping piece 102. Continue to extract the hydraulic oil in the first chamber 100 until the pressure valve 129 opens again. The hydraulic oil in the third chamber 114 flows into the first chamber 100 through the flow channel 128. A negative pressure appears inside the third chamber 114. The first push cylinder 113 moves away from the second clamping piece 111 in the negative pressure environment. At the same time, the first push cylinder 113 drives the first wedge block 112 to move synchronously, and the second clamping piece 111 no longer clamps the steel strand 203. Then, the hydraulic cylinder is removed from the steel strand 203, and the piston rod 108 and the second push cylinder 119 are reset through the oil injection device.

[0054] Finally, the excess steel strand 203 is cut off, and grout is injected into the duct 120 through the grouting port 201.

[0055] The embodiment of the present invention also provides a tensioning method for a post-tensioned prestressed beam, including the following steps: S1, place the steel strand 203 into the prefabricated box girder 200, and pass the steel strand 203 through the sleeve 103 on the telescopic member; there are multiple ducts 120 for the steel strand 203 to pass through in the box girder 200. Each group of steel strands 203 correspondingly passes through one duct 120. The end of the steel strand 203 is located outside the duct 120, and the steel strand 203 passing through the duct 120 is inserted into the corresponding sleeve 103.

[0056] S2. Use the first clamping piece 102 to connect the sleeve 103 and the steel strand 203 together; through the cooperation of the first clamping piece 102 and the sleeve 103, push the sleeve 103 to make it close to the first clamping piece 102. The multiple arc plates in the first clamping piece 102 gradually approach each other under the guidance of the inclined plane of the sleeve 103. After approaching, the first clamping piece 102 will contact the steel strand 203. As the abutting force between the first clamping piece 102 and the steel strand 203 increases, the friction force between them will also increase, and the sleeve 103 and the steel strand 203 can move synchronously in the direction away from the box girder 200.

[0057] S3. Fill hydraulic oil into the first chamber 100 until the pressures in the multiple second chambers 101 are consistent, completing the pre-tightening of the steel strand 203; inject oil into the first chamber 100 through an external oil injection device. The excess hydraulic oil in the first chamber 100 flows into the second chamber 101. The sleeve 103 in the second chamber 101 drives the steel strand 203 away from the box girder 200 under the action of the hydraulic oil, and the steel strand 203 gradually tightens. The volume of the second chamber 101 corresponding to the tightened steel strand 203 will no longer increase before the steel strands 203 in the other second chambers 101 are tightened.

[0058] S4. Start the tensioning mechanism to tension the pre-tightened steel strand 203; after all the steel strands 203 are tightened, the lengths of the steel strands 203 in the duct 120 are the same and the tensile forces they bear are the same. At this time, fix the steel strand 203 again through the second clamping piece 111. The distances between the multiple second clamping pieces 111 and the box girder 200 are the same, ensuring that the tensile forces received by the steel strands 203 in the duct 120 during tensioning are basically the same.

[0059] S5. Start the positioning mechanism to position the tensioned steel strand 203. After the steel strand 203 is tensioned, it is fixed by the third clamping piece 116. The third clamping piece 116 is located between the box girder 200 and the second clamping piece 111. When the third clamping piece 116 contacts the corresponding steel strand 203, there is no relative sliding in the first direction with the steel strand 203. After removing the tensile force of the steel strand 203, the steel strand 203 in the duct 120 will not shrink and can still ensure good tensile force.

[0060] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combinations of these technical features do not conflict, they should all be considered as within the scope described in this specification.

[0061] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. A post-tensioning prestressed beam tensioning device for applying pre-tension stress to a plurality of steel strands extending along a first direction on a box girder, characterized in that, Comprising: A pre-tightening mechanism, a tensioning mechanism and a positioning mechanism. The pre-tightening mechanism includes a telescopic member. The box girder and the telescopic member are arranged along the first direction. A first chamber is provided inside the telescopic member. A plurality of steel strands penetrate through the telescopic member along the first direction and are slidably connected to the telescopic member. A sleeve that slides along the first direction is sleeved on each steel strand. The sleeve is slidably arranged on the telescopic member. A second chamber with variable volume is provided between each sleeve and the telescopic member. The second chamber communicates with the first chamber. Hydraulic oil is filled in the first chamber and the second chamber. When hydraulic oil is filled into the second chamber through the first chamber, the hydraulic oil can push the sleeve away from the box girder. A first wedge grip is provided between each sleeve and the corresponding steel strand to enable the sleeve and the steel strand to be relatively stationary in the first direction. The tensioning mechanism is arranged between the box girder and the telescopic member and can control the reduction of the volume of the first chamber and tension the plurality of steel strands when the sleeve and the corresponding steel strand are relatively stationary. The positioning mechanism is used for clamping and positioning the plurality of tensioned steel strands.

2. The post-tensioning prestressed beam tensioning device according to claim 1, wherein, The tensioning mechanism includes a hydraulic cylinder, a mounting plate and a first power group. The hydraulic cylinder is arranged between the box girder and the telescopic member. The mounting plate is arranged on the hydraulic cylinder. A plurality of first through holes penetrating the mounting plate along the first direction are provided on the mounting plate. Each steel strand penetrates the mounting plate and is located in one of the first through holes. A second wedge grip and a first wedge are provided in each first through hole. The second wedge grip is slidably arranged on the mounting plate along the radial direction of the corresponding steel strand, and the second wedge grip slides to abut against the steel strand. The first wedge is movably arranged on the mounting plate to control the magnitude of the abutting force between the second wedge grip and the steel strand. The first power group is used to provide power for the movement of the first wedge.

3. The post-tensioning prestressed beam tensioning device according to claim 2, characterized in that, The first power group includes a first push cylinder. The first push cylinder is slidably arranged on the telescopic member along the first direction. The first push cylinder is located on the side of the first wedge away from the box girder and is slidably connected to the first wedge. A third chamber containing hydraulic oil and with variable volume is provided between the first push cylinder and the telescopic member. The sliding of the first push cylinder on the telescopic member can change the volume of the third chamber. The telescopic member expands and contracts along the first direction. When the telescopic member elongates or shortens, the volume of the first chamber decreases or increases. A flow channel is provided inside the telescopic member. The flow channel communicates with the first chamber and the third chamber respectively, and a pressure valve is provided in the flow channel.

4. The tensioning device for post-tensioned prestressed beams according to claim 2, characterized in that, The positioning mechanism includes an anchor backing plate, an anchor barrel, a second power group and a positioning component. The anchor backing plate is arranged on the box girder. A plurality of second through holes penetrating the anchor barrel along the first direction are provided on the anchor barrel. The plurality of steel strands penetrate the anchor barrel and are respectively located in one of the second through holes. A third wedge grip and a second wedge are provided in each second through hole. The third wedge grip is slidably arranged on the anchor barrel along the radial direction of the corresponding steel strand, and the third wedge grip slides to abut against the steel strand. The second wedge is movably arranged on the anchor barrel to control the magnitude of the abutting force between the third wedge grip and the steel strand. The second power group provides power for the movement of the second wedge. The positioning component is used for limiting the third wedge grip abutting against the steel strand.

5. A post-tensioned prestressed beam tensioning device according to claim 4, characterized in that, A grouting port is provided on the anchor backing plate.

6. The tensioning device for a post-tensioned prestressed beam according to claim 4, characterized in that, Each of the first wedge grip, the second wedge grip and the third wedge grip includes a plurality of arc plates. When the projections of the plurality of arc plates in the first direction are concentric, there is a spacing between two adjacent arc plates around the first direction.

7. The tensioning device for post-tensioned prestressed beams according to claim 6, characterized in that, On one side of the arc plates in the first clamping piece, the second clamping piece and the third clamping piece close to the corresponding steel strand, spiral grooves with a direction opposite to the helix direction of the steel strand are provided.

8. The tensioning device for a post-tensioned prestressed beam according to claim 4, characterized in that, The number of positioning components is the same as the number of second through holes. Each positioning component is correspondingly arranged in one of the second through holes. Each positioning component includes a clamping block. The number of clamping blocks is the same as that of the arc plates in the third clamping piece. The multiple clamping blocks are arranged around the circumference of the steel strand in the corresponding second through hole. The clamping blocks are slidably arranged on the anchor barrel in the radial direction of the steel strand. A spring piece for driving the clamping blocks to approach the steel strand is provided between each clamping block and the anchor barrel. The clamping blocks are clamped with the third clamping piece in the first direction.

9. The tensioning device for a post-tensioned prestressed beam according to claim 2, characterized in that, The hydraulic cylinder is provided with a lifting lug.

10. A method for tensioning a post-tensioned prestressed beam, which uses a post-tensioned prestressed beam tensioning device according to any one of claims 1 to 9, characterized in that, It includes the following steps: S1. Place the steel strand into the prefabricated box girder and pass the steel strand through the sleeve on the telescopic member. S2. Use the first clamping piece to connect the sleeve and the steel strand together. S3. Fill hydraulic oil into the first chamber until the pressures in the multiple second chambers are the same, and complete the pre-tightening of the steel strand. S4. Start the tensioning mechanism to tension the pre-tightened steel strand. S5. Start the positioning mechanism to position the tensioned steel strand.

Images