Auxiliary device for prestress transfer coefficient test

Abstract

The utility model discloses an auxiliary device for a prestress transfer coefficient test. The auxiliary device is characterized by comprising a positioning plate, a limiting pressing plate, a lug plate and an adjusting bolt. When a prestress transfer coefficient test is carried out, the limiting plate at the passive end can be replaced, so that in the transfer coefficient test process, the distance between the working clamping piece and the working anchor plate can be adjusted and increased, the steel strand is prevented from being locked by the working clamping piece, and the working clamping piece can be smoothly pushed into the working anchor plate after the test is finished; and then oil is returned to anchor the steel strand, so that the retraction amount meets the standard requirement, and the prestress loss is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge prestressed construction, and in particular relates to an auxiliary device for prestressed transfer coefficient testing. Background Art

[0002] During the construction of bridges in foreign French standard systems, the quality control of prestressed bridge construction is very strict. In order to ensure the quality of prestressed construction, according to the French specifications and special technical terms CCTP requirements, prestressed tensioning construction must be tested for transfer coefficients at the frequency required by the specifications. Through the transfer coefficient test, the transfer force of the passive section is verified during the active end tensioning to determine whether the friction resistance and the passive end force meet the requirements of the specifications. Principle and method of the transfer coefficient test: Before prestressing, a limit plate, a jack, and a sensor are installed between the active end working anchor plate and clip and the tool anchor plate and clip, and an auxiliary device, a jack, and a sensor are installed between the passive end working anchor plate and the tool anchor plate. The sensor is connected to a digital display and a laptop computer equipped with a recording program using a special cable. When tensioning begins, both ends are tensioned to the initial stress (20%σk) at the same time, and then the passive end keeps the jack oil pressure stable and does not move. Single-end tensioning is adopted, and the active end is tensioned to 100% in stages (20%σk→40%σk→60σk→80σk→100σk). During the tensioning process, as the tensioning force of the active end jack increases, the tension transmitted to the passive end by the steel strand gradually increases, but due to the influence of friction, there is a certain difference between the two. The computer program will automatically record the stress of the steel strands at both ends at each stage. After the tensioning is completed, the data is substituted into the transfer coefficient formula for calculation and analysis to determine whether the transfer coefficient meets the allowable value of the specification. After the test is completed, the passive end is tensioned to 100% in stages to complete the final tensioning of the prestressed bundle.

[0003] The Abidjan Fourth Bridge Project spans the Banco Bay and has a 1.4-kilometer-long Banco Bay Viaduct. The bridge consists of three parts: the main bridge, the viaduct, and the north-south ramp bridges. The upper structure adopts a prestressed box girder structure. The prestressing form is a combination of internal prestressed tendons and external prestressed tendons. The internal tendons have 19 holes, and the external tendons have 22 holes and 23 holes. The tensioning of the internal and external prestressed tendons must be tested for transfer coefficients at the frequency required by the specifications.

[0004] In the initial stage of the transfer coefficient test, both the active and passive ends adopt the combination of working anchor plate + working clamp + limit plate + jack + sensor + tool clamp + tool anchor plate. The limit plate is a conventional processing form, and a 6mm deep groove is set as the activity space of the clamp during tensioning. When both ends are tensioned to a prestress value of 20%σk at the same time, the working clamp moves 6mm in the direction of the jack and fits closely with the limit plate (that is, the gap between the working clamp and the working anchor plate is 6mm), and the steel strand is not clamped by the clamp. Subsequently, the passive end is kept stable and does not move. When the active end is tensioned by 20%σk-100%σk at one end, the tensioning force should be able to be transmitted to the sensor and the passive end jack through the steel strand. In this process, it should be ensured that the steel strand is not clamped by the working clamp at all times to smoothly transfer the stress. However, in the actual operation, because there is a certain length of steel strand in the working anchor plate and jack at the passive end, as the single-end tensioning of the active end proceeds, this part of the steel strand will have a certain amount of elongation, causing the working clamp at the passive end to move toward the tool anchor plate. When the moving distance is greater than or equal to 6mm, the clamp is embedded in the working anchor plate, clamping and locking the steel strand, and the stress cannot continue to be transmitted to the sensor and jack at the passive end, resulting in test failure. If the groove depth of the passive end limit plate is increased, the retraction amount will exceed the allowable value of the specification when the return oil is locked, and the prestress loss will be large, which does not meet the specification requirements. Therefore, the conventional limit plate at the passive end cannot successfully complete the transfer coefficient test. Utility Model Content

[0005] In order to solve the above problems, the utility model provides an auxiliary device for prestressed transfer coefficient test to replace the limit plate at the passive end, so that during the transfer coefficient test, it can adjust and increase the distance between the working clamp and the working anchor plate to avoid the working clamp locking the steel strand; after the test, the working clamp can be smoothly pushed into the working anchor plate, and then the oil can be returned to anchor the steel strand, ensuring that the retraction amount meets the specification requirements and reducing prestress loss.

[0006] The utility model is achieved through the following technical solutions.

[0007] An auxiliary device for prestress transfer coefficient test, characterized by comprising a positioning plate, a limit pressure plate, a lug plate and an adjusting bolt;

[0008] The positioning plate is a hollow annular structure, the front end of the positioning plate is provided with a positioning groove along its length direction, the front end surface of the positioning plate is provided with an annular groove, the front end of the positioning plate is sleeved with the working anchor plate through the annular groove, and the rear end of the positioning plate is connected to the jack;

[0009] The limiting pressure plate is a circular steel plate, and a support leg is arranged on the outer side of the limiting pressure plate. The limiting pressure plate is installed in the positioning plate by embedding the support leg into the positioning groove; the ear plate is a hollow annular structure, and the ear plate is sleeved on the working anchor plate and connected to the support leg through an adjusting bolt.

[0010] Preferably, three positioning grooves are evenly arranged along the circumferential direction at the front end of the positioning plate, and three supporting legs are evenly arranged along the outer side of the limiting pressure plate.

[0011] Preferably, the limiting pressure plate is provided with steel strand holes with the same number and specification as those of the working anchor plate.

[0012] Preferably, the positioning plate, the limiting pressure plate and the ear plate are all made of thick steel plates, and their strength is calculated to meet the force requirements.

[0013] Preferably, along the length direction of the front end of the positioning plate, the depth of the positioning groove is 55-65 mm, the depth of the annular groove is 4-10 mm; and the thickness of the limiting pressure plate is 15-25 mm.

[0014] Compared with the existing technology, the utility model has the following advantages:

[0015] 1. When the utility model is used to test the prestress transfer coefficient, the range of motion of the working clip is enlarged and the spacing can be adjusted, so that the adjusting bolt can be screwed as needed to adjust the distance from the working clip to the working anchor plate, so that when the active end is tensioned, the passive end working clip can be effectively prevented from moving and locking the steel strand. After the prestress transfer coefficient test is completed, the adjusting bolt can be tightened, and the working clip can be pushed into the working anchor plate using the limit pressure plate, and then the jack is used to relieve pressure, so that the working clip completes self-anchoring, and the retraction amount meets the specification requirements.

[0016] 2. The utility model has a simple structure, is easy to operate, and has strong adaptability. It can process auxiliary devices of different types of anchors according to needs, and can be circulated and reused, and has good promotion and practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the utility model;

[0018] Figure 2 It is a right side view of the positioning plate in the utility model;

[0019] Figure 3 for Figure 2 Sectional view at mid-AA;

[0020] Figure 4 It is a right side view of the limit pressing plate in the utility model;

[0021] Figure 5 for Figure 3 Sectional view at the middle BB;

[0022] Figure 6 It is a right side view of the middle ear plate of the utility model;

[0023] Figure 7 It is a schematic diagram of using the utility model to conduct a prestress transfer coefficient test;

[0024] Figure 8 This is a schematic diagram of the prestress transfer coefficient test after pressure relief using the utility model;

[0025] The meanings of the symbols in the above figure are: positioning plate 1, positioning groove 101, annular groove 102, limiting pressure plate 2, support leg 201, steel strand hole 202, ear plate 3, adjusting bolt 4, working anchor plate 5, sensor 6, limiting plate 7, jack 8, tool clip 9, tool anchor plate 10, working clip 11. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention will be described in more detail below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings, but the present invention can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the content disclosed in the present invention more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. The present invention is further described in detail below in conjunction with the accompanying drawings.

[0028] Example 1

[0029] An auxiliary device for prestress transfer coefficient test, see Figures 1 to 8 , which includes a positioning plate 1, a limiting pressure plate 2, a lug plate 3 and an adjusting bolt 4;

[0030] Among them, the positioning plate 1 is a hollow annular structure, which is made of 110mm thick steel plate as a whole, with an inner diameter set to 207mm according to the size of the working anchor plate 5, an outer diameter of the front end is 269mm, and an outer diameter of the rear end is 358mm; the front end of the positioning plate 1 is provided with a positioning groove 101 along its length direction for installing the limiting pressure plate 2; the front end surface of the positioning plate 1 is provided with an annular groove 102, the front end of the positioning plate 1 is sleeved on the working anchor plate 5 through the annular groove 102, connected and limited with the working anchor plate, and the rear end of the positioning plate 1 is embedded in the jack groove, connected and limited with the jack 8; the width of the annular groove 102 is 19mm and the depth is 5mm; the positioning groove 101 is provided with three circumferential directions at the front end of the positioning plate, that is, the angle between the positioning grooves 101 is 120 degrees, the width of the positioning groove 101 is 38mm, and the depth is 60mm; the positioning plate 1 is the main bearing component of the tension force, and its strength is calculated to meet the force requirements, and the material is the same as the limiting plate;

[0031] The limit pressure plate 2 is a circular steel plate with a diameter of 205 mm, made of a 20 mm thick steel plate, with 23 steel strand holes 202 opened on the limit pressure plate 2, with a hole diameter of 21 mm and a hole spacing of 33 mm, which are the same as the working anchor plate 5; three legs 201 with a width of 35 mm are arranged on the outer side of the limit pressure plate 2, and the angle between the legs 201 is 120 degrees, which are used to embed in the positioning groove 101, so that the limit pressure plate 2 is installed in the positioning plate 1; a bolt hole with a diameter of 17 mm is arranged on the outer end of each leg 201, for installing the adjusting bolt 4;

[0032] The ear plate 3 is made of 15mm thick steel plate, is a hollow ring, has an inner diameter of 245mm, and an outer diameter of 358mm, and is provided with three bolt holes with a diameter of 17mm, with an angle of 120 degrees between the holes, corresponding to the position of the bolt holes on the leg 201; the ear plate 3 is sleeved on the working anchor plate 5 and connected to the leg 201 through the adjusting bolt 4;

[0033] Based on the above structure, by replacing the limit plate at the passive end with the utility model, the range of motion of the working clamp 11 can be expanded from the original 6mm spacing fixed by the limit plate to 60-5-20=35mm (that is, the depth of the positioning groove minus the depth of the annular groove and the thickness of the limit pressure plate), so that during the transfer coefficient test, it can adjust and increase the distance between the working clamp 11 and the working anchor plate 5 to avoid the working clamp locking the steel strand, and after the test, the limit pressure plate can be used to smoothly push the working clamp 11 into the working anchor plate, and then return the oil to anchor the steel strand, ensuring that the retraction amount meets the specification requirements and reduces the prestress loss.

[0034] Example 2

[0035] See also Figure 7 and Figure 8The method for conducting a prestress transfer coefficient test using the auxiliary device of the utility model is as follows:

[0036] 1. Insert the steel strand into the prestressed pipe and install the working anchor plates and working clips at the active and passive ends.

[0037] 2. Install the limit plate, jack, sensor, tool anchor plate and tool clip on the active end in sequence.

[0038] 3. Install the auxiliary device, jack, sensor, tool anchor plate and tool clip at the passive end in sequence, and adjust the adjusting bolt of the auxiliary device at the passive end so that the distance between the auxiliary device limit pressure plate and the working anchor plate is 30 mm.

[0039] 4. Connect the active and passive sensors to the digital display with special cables, and connect the digital displays at both ends to the laptop with special cables.

[0040] 5. Both ends are tensioned simultaneously to an initial stress of 20%σk, the elongation of the steel strand is measured, and the tensioning force is recorded on the digital displays at both ends. At this time, the working clip at the passive end extends 30mm out of the working anchor plate, and the passive end is stabilized and does not move.

[0041] 6. Tension the active end in stages to 40%σk, 60%σk, 80%σk, and 100%σk, measure the elongation of the steel strand at each stage, and record the tension on the digital displays at both ends.

[0042] 7. Substitute the tension forces at both ends recorded in each stage into the transfer coefficient calculation formula for calculation and analysis. The test ends when it passes the test.

[0043] 8. Keep the active end steady and tension the passive end to 100%. Measure the elongation value, calculate the total elongation value and compare it with the designed elongation value. When it meets the requirements of the specification, tensioning is terminated.

[0044] 9. Tighten the adjusting bolt of the passive end auxiliary device and use the limit pressure plate to push the clip into the working anchor plate.

[0045] 10. The jacks at the active and passive ends are simultaneously unloaded in stages, and the clips at both ends are retracted into the working anchor plate to clamp the self-anchor. After the pressure unloading is completed, the retraction amount at both ends is measured and calculated and verified to ensure that the retraction amount meets the requirements of the specifications.

Claims

1. An auxiliary device for prestress transfer coefficient test, characterized in that It comprises a positioning plate (1), a limiting pressure plate (2), a lug plate (3) and an adjusting bolt (4); The positioning plate (1) is a hollow annular structure, the front end of the positioning plate (1) is provided with a positioning groove (101) along its length direction, the front end surface of the positioning plate (1) is provided with an annular groove (102), the front end of the positioning plate (1) is sleeved with the working anchor plate (5) through the annular groove (102), and the rear end of the positioning plate (1) is connected to the jack (8); The limiting pressure plate (2) is a circular steel plate, and a support leg (201) is arranged on the outer side of the limiting pressure plate (2). The limiting pressure plate (2) is installed in the positioning plate (1) by embedding the support leg (201) into the positioning groove (101); the ear plate (3) is a hollow annular structure, and the ear plate (3) is sleeved on the working anchor plate (5) and connected to the support leg (201) through an adjusting bolt (4).

2. An auxiliary device for prestress transfer coefficient test according to claim 1, characterized in that: The positioning grooves (101) are evenly arranged in three rows along the circumferential direction at the front end of the positioning plate (1), and the supporting legs (201) are evenly arranged in three rows along the outer side of the limiting pressure plate (2).

3. An auxiliary device for prestress transfer coefficient test according to claim 1, characterized in that: The limit pressure plate (2) is provided with steel strand holes (202) of the same number and specification as the working anchor plate (5).

4. An auxiliary device for prestress transfer coefficient test according to claim 1, characterized in that: The positioning plate (1), the limiting pressure plate (2) and the ear plate (3) are all made of thick steel plates, and their strength is calculated to meet the force requirements.

5. An auxiliary device for prestress transfer coefficient test according to claim 1, characterized in that: Along the length direction of the front end of the positioning plate (1), the depth of the positioning groove (101) is 55 to 65 mm, the depth of the annular groove (102) is 4 to 10 mm; and the thickness of the limiting pressure plate (2) is 15 to 25 mm.

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