Measuring device and method for measuring effective prestress of prestressed beam

Abstract

The invention relates to a measuring device and method for measuring effective prestress of a prestressed beam, and belongs to the technical field of prestress measurement, the measuring device comprises two mounting plates, bosses and strain gages, the strain gages are fixed on prestressed tendons, the two mounting plates are fixedly arranged on the prestressed tendons, the strain gages are located between the two mounting plates, and the bosses are arranged on the bosses. The boss is fixedly arranged on the mounting plate and faces the strain gauge, and a connecting wire of the strain gauge penetrates out of the prestressed beam along the trend of the prestressed tendon after passing through the boss and the mounting plate; the cross sections of the mounting plate and the bosses are circular, the measuring device further comprises an encircling piece, and the encircling piece is used for encircling the bosses on the two sides to seal the strain gauges between the bosses and the encircling piece; the cross sections of the mounting plate and the bosses are circular, and the measuring device further comprises a surrounding piece which is used for surrounding the bosses on the two sides so that the strain gauges can be sealed between the bosses and the surrounding piece. The device has the effect of conveniently measuring the pre-stress of the pre-stressed beam.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of prestress measurement, in particular to a measuring device and method for measuring effective prestress of a prestressed beam. BACKGROUND

[0002] The prestressed beam can overcome the maximum defect of the ordinary reinforced beam, i.e. the crack problem, due to its prestress, and the prestressed concrete structure can not only save steel material but also improve the structure function and solve the technical problems that other structure materials cannot solve, so the prestressed beam is widely used in large structures with high technical difficulty such as large bridges. The safety state of the prestressed beam during the service period is directly related to the size of the internal effective prestress, but as the service period increases, the structure prestress will gradually be lost, i.e. the stress in the prestressed tendon gradually decreases, so it is necessary to measure the effective prestress in the prestressed beam.

[0003] However, when measuring the effective prestress at present, it is usually necessary to partially destroy the prestressed beam to expose the prestressed tendon, and then a tensile force opposite to the prestress is applied to the prestressed tendon by clamping the prestressed tendon, when the applied tensile force completely offsets the prestress, i.e. the applied tensile force is the effective prestress of the prestressed tendon, but the destruction of the prestressed beam and the pulling of the prestressed tendon after the destruction of the prestressed beam will destroy the integrity of the prestressed beam, so that the bearing capacity and deformation resistance of the prestressed beam after the measurement of the prestress cannot be restored and the difficulty of the measurement of the prestress is relatively large. SUMMARY

[0004] In order to facilitate the measurement of the prestress of the prestressed beam, the present application provides a measuring device and method for measuring the effective prestress of the prestressed beam.

[0005] In the first aspect, the present application provides a measuring device for measuring the effective prestress of the prestressed beam, which adopts the following technical scheme: A measuring device for measuring the effective prestress of the prestressed beam, comprising a mounting plate, a boss and a strain gauge, the strain gauge is fixed on the prestressed tendon, the mounting plate is provided with two mounting plates and is fixedly arranged on the prestressed tendon, the strain gauge is located between the two mounting plates, the boss is fixedly arranged on the mounting plate and faces the strain gauge, and the connecting lead of the strain gauge passes through the boss and the mounting plate and then is pulled out from the prestressed beam along the running direction of the prestressed tendon; The cross sections of the mounting plate and the boss are circular, and the measuring device further comprises a surrounding part, which is used to seal the strain gauge between the boss and the surrounding part by surrounding the bosses on both sides; The measuring device further comprises a dehumidifying part, which is used to discharge the humid air between the surrounding part and the boss so as to make the strain gauge in a dry environment.

[0006] Optionally, the enclosing member comprises a winding shaft, a waterproof film and a first driving member, the length direction of the winding shaft is parallel to the length direction of the prestressed tendon, the waterproof film is wound on the winding shaft, the two ends of the winding shaft are located on the two bosses respectively and cross the strain gauge, and the first driving member is used to drive the winding shaft to move around the boss to drive the waterproof film to surround and be sleeved on the boss to seal the strain gauge.

[0007] Optionally, the surface of the mounting plate towards the strain gauge is provided with an annular groove, the boss is fixedly arranged in the middle of the annular groove, the two ends of the winding shaft are provided with mounting seats, the winding shaft is rotatably arranged on the mounting seat, the mounting seat is slidably arranged on the side wall of the annular groove, the first driving member comprises a driving ring, a driving gear and a driving motor, the driving ring is rotatably arranged in the annular groove, the mounting seat is fixedly arranged in the inner ring of the driving ring, the inner ring of the driving ring is provided with a toothed section, the toothed section is located on one side of the driving ring, the driving motor is embedded in the mounting plate, and the driving gear is arranged on the output shaft of the driving motor and is in meshing connection with the toothed section.

[0008] Optionally, the compensating member comprises a first spring and an extension tube, the mounting seat comprises a fixed seat and a sliding seat, the fixed seat is fixedly arranged on the inner side of the driving ring, the winding shaft is rotatably arranged on the side wall of the sliding seat, and the sliding seat is located on the fixed seat and is slidably arranged on the fixed seat. The extension tube is fixedly arranged between the fixed seat and the sliding seat, and the first spring is sleeved on the extension tube to drive the sliding seat to slide towards the boss to drive the waterproof film to abut against the boss.

[0009] Optionally, the enclosing member further comprises a sealing member, the sealing member comprises a glue applying roller, a glue applying groove and a second driving member, the glue applying groove is arranged on the sliding seat, the opening direction of the glue applying groove is towards the waterproof film, the glue applying roller is rotatably arranged in the glue applying groove and abuts against the outer side of the waterproof film, and the second driving member is used to drive the glue applying groove to move towards the winding shaft to make the glue applying roller abut against the outer side of the waterproof film.

[0010] Optionally, the glue applying roller crosses the end portion of the waterproof film on the winding shaft.

[0011] Optionally, the dehumidifying member comprises an air pipe and an air valve, the air pipe passes through the boss and the mounting plate and moves out of the prestressed beam along the running direction of the prestressed tendon, the air valve is arranged on the air pipe, and the other end of the air pipe is used to be connected with a gas supply device to extract the humid air between the waterproof film and the boss and discharge the humid air through the air pipe.

[0012] Optionally, the dehumidifying member comprises an air pipe and an air valve, the air pipe passes through the boss and the mounting plate and extends out of the pre-stressed beam along the direction of the pre-stressed tendon, the air valve is arranged on the air pipe, and the other end of the air pipe is connected with a gas supply device to extract the humid air between the waterproof film and the boss and discharge the humid air through the air pipe.

[0013] Optionally, the measuring device further comprises a supporting net sleeved on the pre-stressed tendon, the supporting net is convex, and the strain gauge is located below the supporting net.

[0014] In the second aspect, the application provides a measuring method for measuring the effective pre-stress of a pre-stressed beam, and the method adopts the following technical scheme: The measuring method for measuring the effective pre-stress of a pre-stressed beam uses the measuring device for measuring the effective pre-stress of a pre-stressed beam, and further comprises the following steps of: S1. When the pre-stressed tendon of the pre-stressed beam is built, the mounting plate and the boss are mounted on the pre-stressed tendon, the mounting plate and the boss are sleeved on the pre-stressed tendon, and the gap between the mounting plate, the boss and the pre-stressed tendon is sealed; S2. The strain gauge is fixed on the pre-stressed tendon, and the waterproof film is wound on the boss to seal the strain gauge; S3. The pre-stressed tendon is subjected to tensile stress, and the pre-stress is fed back through the resistance value of the strain gauge; S4. When the waterproof film is damaged due to stretching or long-term use, the driving motor is started, the driving motor drives the driving gear and the driving ring to rotate, the driving ring drives the winding shaft to rotate to re-sleeve the waterproof film on the boss, so as to cover the damaged waterproof film again; S5. When the waterproof film is covered again, the glue roller applies waterproof glue to the outer side of the waterproof film to seal and connect the adjacent layers of the waterproof film, and part of the glue penetrates to the inner side of the waterproof film through the edge of the waterproof film to seal the adjacent layers of the waterproof film.

[0015] The technical scheme of the application has at least the following advantages and beneficial effects: 1. When measuring the effective stress on the prestressed tendon, the effective stress on the prestressed tendon is fed back through the resistance change of the strain gauge; after the strain gauge is fixedly installed on the prestressed tendon, the strain gauge is enclosed between two convex tables by the action of the enclosing member on the convex tables, and is sealed between the convex tables and the enclosing member, thereby reducing the influence of the humid environment on the resistance value of the strain gauge, and further improving the measurement accuracy of the prestress; at the same time, the strain gauge is sealed under the action of the enclosing member, compared with using clay or glue to separate the strain gauge from the humid environment, the influence of clay or glue on the deformation of the strain gauge is reduced, and the accuracy of the measurement value is further improved; at the same time, when the strain gauge is connected with current, the strain gauge will generate heat, if the strain gauge is separated from the environment by clay, etc., the heat generated by the strain gauge cannot be quickly conducted, and is easy to accumulate in the strain gauge and clay, resulting in large measurement error of the strain gauge and cracking of the clay due to temperature rise, and the strain gauge and the environment cannot be well separated, under the action of the enclosing member, the strain gauge is separated from the environment, and the strain gauge and the enclosing member are in a separated state, and the strain gauge is easy to quickly dissipate heat.

[0016] 2. After the enclosing member and the convex table enclose the strain gauge, the humid air in the enclosing member is extracted by the dehumidifying member, so that the space where the strain gauge is located is close to a vacuum state, further reducing the influence of environmental factors on the strain gauge, thereby improving the accuracy of the prestress measurement. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0018] Figure 1 is a whole structure schematic diagram of a measuring device for measuring the effective prestress of a prestressed beam according to an embodiment of the present application; Figure 2 is a structure schematic diagram of an enclosing member in a measuring device for measuring the effective prestress of a prestressed beam according to an embodiment of the present application; Figure 3 is a structure schematic diagram of a strain gauge in a measuring device for measuring the effective prestress of a prestressed beam according to an embodiment of the present application; Figure 4 is a sectional view of a mounting plate and a convex table in a measuring device for measuring the effective prestress of a prestressed beam according to an embodiment of the present application.

[0019] Explanation of reference numerals: 1, mounting plate; 2, convex table; 3, strain gauge; 4, connecting lead wire; 5, enclosing member; 51, winding shaft; 52, waterproof film; 53, driving ring; 54, driving gear; 55, driving motor; 56, toothed section; 57, first spring; 58, telescopic tube; 59, glue roller; 510, glue groove; 511, second spring; 512, telescopic rod; 6, dehumidifying member; 61, air pipe; 62, air valve; 7, annular groove; 8, mounting base; 81, fixed seat; 82, sliding seat; 9, sealing groove; 10, supporting net; 11, prestressed tendon. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will be a clear and complete description of the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0022] The following is further illustrated in conjunction with specific embodiments, with reference to Figure 1 , Figure 2 and Figure 3 , the measuring device for measuring the effective prestress of a prestressed beam comprises a mounting plate 1, a boss 2, and a strain gauge 3, the strain gauge 3 is fixed on the prestressed tendon 11, the mounting plate 1 is provided with two pieces and is fixedly arranged on the prestressed tendon 11, the strain gauge 3 is located between the two mounting plates 1, the boss 2 is fixedly arranged on the mounting plate 1 and faces the strain gauge 3, the connecting lead 4 of the strain gauge 3 passes through the boss 2 and the mounting plate 1 and then is led out from the prestressed beam along the running direction of the prestressed tendon 11; With reference to Figure 2 , Figure 3 and Figure 4 , the cross sections of the mounting plate 1 and the boss 2 are both circular, and the measuring device further comprises an enclosing member 5, the enclosing member 5 is used for sealing the strain gauge 3 between the boss 2 and the enclosing member 5 by surrounding the two bosses 2.

[0023] When the strain gauge 3 is fixedly installed on the prestressed tendon 11, the strain gauge 3 is enclosed between the two bosses 2 by the action of the enclosing member 5 on the bosses 2 and sealed between the bosses 2 and the enclosing member 5, thereby reducing the influence of the humid environment on the resistance value of the strain gauge 3, and further improving the measurement accuracy of the prestress; at the same time, the strain gauge 3 is sealed under the action of the enclosing member 5, compared with using clay or glue to separate the strain gauge 3 from the humid environment, the influence of the clay or glue on the deformation of the strain gauge 3 is reduced, and the accuracy of the measurement value is further improved; at the same time, when the strain gauge 3 is passed through the current, the strain gauge 3 will generate heat, if the strain gauge 3 is separated from the environment by clay and the like, the heat generated by the strain gauge 3 cannot be quickly conducted, and is easy to accumulate in the strain gauge 3 and the clay, resulting in a large measurement error of the strain gauge 3 and cracking of the clay due to the temperature rise, and the strain gauge 3 and the environment cannot be well separated, under the action of the enclosing member 5, the strain gauge 3 is separated from the environment, and the strain gauge 3 and the enclosing member 5 are in a separated state, and the strain gauge 3 is easy to quickly dissipate heat.

[0024] With reference to Figure 1 In order to further improve the measurement accuracy of the prestress, the measuring device further comprises a dehumidifying member 6, which is used to exhaust the humid air between the enclosing member 5 and the boss 2 to make the strain gauge 3 in a dry environment; after the enclosing member 5 and the boss 2 enclose the strain gauge 3, the humid air in the enclosing member 5 is extracted by the dehumidifying member 6, so that the space where the strain gauge 3 is located is close to a vacuum state, further reducing the influence of environmental factors on the strain gauge 3, thereby improving the accuracy of the measurement of the prestress.

[0025] With reference to Figure 3 and Figure 4 In the embodiment of the present application, the enclosing member 5 comprises a winding shaft 51, a waterproof film 52 and a first driving member, the length direction of the winding shaft 51 is parallel to the length direction of the prestressed tendon 11, the waterproof film 52 is wound on the winding shaft 51, the waterproof film 52 is wound with multiple layers, and the two ends of the winding shaft 51 are located on the two bosses 2 and span the strain gauge 3, and the first driving member is used to drive the winding shaft 51 to move around the boss 2 to drive the waterproof film 52 to surround and be sleeved on the boss 2 to seal the strain gauge 3; With reference to Figure 3 and Figure 4The face of the mounting plate 1 towards the strain gauge 3 is provided with an annular groove 7, the boss 2 is fixedly arranged in the middle of the annular groove 7, both ends of the winding shaft 51 are provided with mounting seats 8, the winding shaft 51 is rotationally arranged on the mounting seat 8, the mounting seat 8 is slidingly arranged on the side wall of the annular groove 7, the first driving member comprises a driving ring 53, a driving gear 54 and a driving motor 55, the driving ring 53 is rotationally arranged in the annular groove 7, the mounting seat 8 is fixedly arranged in the inner ring of the driving ring 53, the inner ring of the driving ring 53 is provided with a toothed section 56, the toothed section 56 is located on one side of the driving ring 53, the driving motor 55 is embedded in the mounting plate 1, and the driving gear 54 is arranged on the output shaft of the driving motor 55 and is in meshing connection with the toothed section 56.

[0026] After the strain gauge 3 is fixed on the prestressed tendon 11, the driving motor 55 is started, the driving motor 55 drives the driving gear 54 to rotate, the driving gear 54 drives the driving ring 53 to rotate, the driving ring 53 drives the mounting seat 8 to rotate, the mounting seat 8 drives the winding shaft 51 to rotate around the circumference of the boss 2, and the winding shaft 51 drives the waterproof film 52 to surround the boss 2 when rotating, so that the strain gauge 3 is sealed in the boss 2 and the waterproof film 52, and the operation is simple and convenient; further, since the waterproof film 52 is sleeved on the boss 2, the waterproof film 52 is in a separated state from the strain gauge 3, so that the influence of the waterproof film 52 on the strain gauge 3 is reduced; further, when the surrounded waterproof film 52 is locally damaged, the driving motor 55 drives the winding shaft 51 to rotate to surround the waterproof film 52 on the boss 2 again, so as to cover the damaged waterproof film 52, thereby restoring the sealing performance of the waterproof film 52.

[0027] Referring to Figure 3 and Figure 4, with the waterproof film 52 sleeved on the boss 2, the waterproof film 52 on the winding shaft 51 gradually reduces in thickness, causing the outermost waterproof film 52 to be difficult to abut on the boss 2, thereby causing a large gap between the waterproof films 52 of adjacent layers, and causing the sealing performance of the waterproof film 52 to be general, therefore, in the embodiment of the application, the enclosing member 5 further comprises a compensation member, the compensation member being used to drive the waterproof film 52 wound on the winding shaft 51 to abut on the boss 2 during the waterproof film 52 being sleeved on the boss 2, the compensation member comprising a first spring 57 and an extension tube 58, the mounting seat 8 comprising a fixed seat 81 and a sliding seat 82, the fixed seat 81 being fixedly arranged inside the driving ring 53, the winding shaft 51 being rotatably arranged on the side wall of the sliding seat 82, the sliding seat 82 being located on the fixed seat 81 and slidably arranged on the fixed seat 81, the sliding seat 82 sliding in a direction perpendicular to the fixed seat 81, the extension tube 58 being fixedly arranged between the fixed seat 81 and the sliding seat 82, the first spring 57 being sleeved on the extension tube 58 and used to drive the sliding seat 82 to slide towards the boss 2 to drive the waterproof film 52 to abut on the boss 2; when the driving ring 53 drives the winding shaft 51 to sleeve the waterproof film 52 on the boss 2, with the waterproof film 52 on the winding shaft 51 gradually reducing in thickness, under the action of the first spring 57, the sliding seat 82 is driven to move towards the winding shaft 51, the sliding seat 82 drives the winding shaft 51 and the waterproof film 52 to move close to the boss 2, so that the waterproof film 52 abuts on the outside of the boss 2, thereby improving the sealing performance of the waterproof film 52.

[0028] With reference to Figure 3 and Figure 4 , the waterproof film 52 only surrounds and sleeves the boss 2, causing the sealing performance between the waterproof films 52 of adjacent layers to be general, in order to improve the sealing performance between the waterproof films 52 of adjacent layers, the enclosing member 5 further comprises a sealing member, the sealing member comprising a glue applying roller 59, a glue applying groove 510 and a second driving member, the glue applying groove 510 being arranged on the sliding seat 82, the opening direction of the glue applying groove 510 facing the waterproof film 52, the glue applying roller 59 being rotatably arranged in the glue applying groove 510 and abutting on the outside of the waterproof film 52, further, the glue applying groove 510 is slidably arranged on the side wall of the sliding seat 82, the glue applying groove 510 sliding in a direction perpendicular to the winding shaft 51, the second driving member being used to drive the glue applying groove 510 to move towards the winding shaft 51 so that the glue applying roller 59 abuts on the outside of the waterproof film 52, the second driving member comprising a second spring 511, one end of the second spring 511 being fixedly arranged inside the driving ring 53, the other end being fixedly arranged on the bottom of the glue applying groove 510, further, the second driving member further comprises an extension rod 512 arranged between the driving ring 53 and the glue applying groove 510.

[0029] When the driving ring 53 drives the winding shaft 51 to rotate around the boss 2, the waterproof film 52 is wrapped around the boss 2, and in this process, the glue groove 510 is driven to move the glue roller 59 towards the waterproof film 52 under the action of the second spring 511, so that the glue roller 59 abuts on the outer side of the waterproof film 52, and the glue roller 59 rotates to apply glue on the waterproof film 52 in this process, and after the outer waterproof film 52 is covered on the inner waterproof film 52, the outer waterproof film 52 is pasted on the inner waterproof film 52, thereby improving the sealing performance of the adjacent layers of the waterproof film 52.

[0030] With reference to Figure 3 And Figure 4 To further improve the sealing performance of the waterproof film 52, the glue roller 59 spans the end of the waterproof film 52 on the winding shaft 51; after the glue roller 59 applies waterproof glue, the glue on the edge of the waterproof film 52 flows over the end of the waterproof film 52 to the inner side of the waterproof film 52 to seal and bond the inner and outer sides of the waterproof film 52.

[0031] The glue on the edge of the waterproof film 52 flows towards the lateral end of the waterproof film 52 under the action of the pressure joint, and flows to the inner side of the waterproof film 52 to seal and bond the inner and outer sides of the waterproof film 52.

[0032] With reference to Figure 1 In the embodiment of the application, the dehumidifying member 6 includes an air pipe 61 and an air valve 62, the air pipe 61 passes through the boss 2 and the mounting plate 1 and moves out of the prestressed beam along the direction of the prestressed tendon 11, the air valve 62 is arranged on the air pipe 61, and the other end of the air pipe 61 is used to connect an air supply device to extract the humid air between the waterproof film 52 and the boss 2 and discharge the humid air through the air pipe 61; after the waterproof film 52 is sleeved on the boss 2, the air pipe 61 is connected to the air supply device, and the humid air in the waterproof film 52 is extracted through the air supply device, so that the strain gauge 3 is in a dry environment, and the operation is simple and convenient; at the same time, after the humid air in the waterproof film 52 is extracted, dry air is injected into the waterproof film 52 through the air supply device to replace the humid air, thereby further improving the test accuracy of the prestress and prolonging the service life of the strain gauge 3.

[0033] With reference to Figure 3 And Figure 4In the embodiment of the present application, in order to improve the sealing performance between the innermost waterproof film 52 and the boss 2, a sealing groove 9 is arranged on the outer ring of the boss 2, the sealing groove 9 is connected in a ring shape, a connecting channel is arranged in the boss 2, the connecting channel is used for connecting the sealing groove 9 and the air pipe 61, and when the humid air is extracted by the air supply device, the air in the sealing groove 9 is extracted to suck the waterproof film 52 into the sealing groove 9; after the waterproof film 52 is sleeved on the boss 2, the humid air is extracted by the air supply device, at this time, the air in the sealing groove 9 is extracted, so that the innermost waterproof film 52 moves towards the sealing groove 9, thereby improving the sealing performance between the waterproof film 52 and the boss 2.

[0034] With reference to Figure 2 And Figure 3 When the humid gas in the waterproof film 52 is extracted, the waterproof film 52 has a tendency to be concave towards the prestressed tendon 11 and is crimped on the strain gauge 3, which hinders the deformation of the strain gauge 3, therefore, in the embodiment of the present application, the measuring device further comprises a supporting net 10 sleeved on the prestressed tendon 11, the supporting net 10 is convex, and the strain gauge 3 is located below the supporting net 10; under the action of the supporting net 10, the waterproof film 52 and the strain gauge 3 are separated, thereby reducing the hindering of the waterproof film 52 to the strain gauge 3 and improving the accuracy of the prestress measurement data.

[0035] The implementation principle of the measuring device for measuring the effective prestress of the prestressed beam in the embodiment of the present application is as follows: After the strain gauge 3 is fixedly installed on the prestressed tendon 11, the strain gauge 3 is enclosed between the two bosses 2 by the action of the enclosing member 5 on the boss 2 and is sealed between the boss 2 and the enclosing member 5, thereby reducing the influence of the humid environment on the resistance value of the strain gauge 3 and further improving the measurement accuracy of the prestress; meanwhile, the strain gauge 3 is sealed under the action of the enclosing member 5, compared with separating the strain gauge 3 from the humid environment by using clay or glue, the influence of the clay or glue on the deformation of the strain gauge 3 is reduced, and the accuracy of the measurement value is further improved; meanwhile, when the strain gauge 3 is electrified, the strain gauge 3 generates heat, if the strain gauge 3 is separated from the environment by using clay and the like, the heat generated by the strain gauge 3 cannot be quickly conducted and is easy to accumulate in the strain gauge 3 and the clay, which leads to large measurement error of the strain gauge 3 and cracking of the clay due to temperature rise, and the strain gauge 3 cannot be well separated from the environment, under the action of the enclosing member 5, the strain gauge 3 is separated from the environment, and the strain gauge 3 is in a separated state with the enclosing member 5, thereby facilitating the rapid heat dissipation of the strain gauge 3.

[0036] The embodiment of the present application discloses a measuring method for measuring the effective prestress of a prestressed beam, using a measuring device for measuring the effective prestress of a prestressed beam, and further comprising; S1: when the prestressed tendon 11 of the prestressed beam is built, the mounting plate 1 and the boss 2 are installed on the prestressed tendon 11, the mounting plate 1 and the boss 2 are installed by penetrating the prestressed tendon 11, and after the mounting plate 1 and the boss 2 are sleeved on the prestressed tendon 11, the gap between the mounting plate 1 and the boss 2 and the prestressed tendon 11 is sealed; S2: the strain gauge 3 is fixed on the prestressed tendon 11, and the waterproof film 52 is wound on the boss 2, and the waterproof film 52 is sealed by surrounding the strain gauge 3; S3: the prestressed tendon 11 is applied with tensile stress, and the prestress is fed back through the resistance value of the strain gauge 3; S4: when the waterproof film 52 is damaged due to stretching or long-term use, the driving motor 55 is started, the driving motor 55 drives the driving gear 54 and the driving ring 53 to rotate, the driving ring 53 drives the winding shaft 51 to rotate to re-sleeve the waterproof film 52 on the boss 2, so as to re-cover the damaged waterproof film 52; S5: when the waterproof film 52 is re-covered, the glue roller 59 applies waterproof glue to the outside of the waterproof film 52, so as to seal and connect the adjacent layers of the waterproof film 52, and part of the glue penetrates to the inside of the waterproof film 52 through the edge of the waterproof film 52 to seal the adjacent layers of the waterproof film 52.

[0037] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, so: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A measuring device for measuring the effective prestress of a prestressed beam, characterized by: The invention comprises a mounting plate (1), a boss (2) and a strain gauge (3), wherein the strain gauge (3) is fixed on a prestressed tendon (11), two mounting plates (1) are provided and fixedly arranged on the prestressed tendon (11), the strain gauge (3) is located between the two mounting plates (1), the boss (2) is fixedly arranged on the mounting plate (1) and faces the strain gauge (3), and the connecting wire (4) of the strain gauge (3) passes through the boss (2) and the mounting plate (1) and then passes out from the prestressed beam along the direction of the prestressed tendon (11); The cross-sections of the mounting plate (1) and the boss (2) are both circular, and the measuring device further comprises an enclosure (5), wherein the enclosure (5) is used to surround the boss (2) on both sides and seal the strain gauge (3) between the boss (2) and the enclosure (5); The measuring device further comprises a dehumidifying component (6), which is used to discharge the moist air between the enclosing component (5) and the boss (2) so as to place the strain gauge (3) in a dry environment.

2. The device for measuring the effective prestress of a prestressed beam according to claim 1, characterized in that: The enclosing member (5) comprises a reel (51), a waterproof film (52) and a first driving member. The length direction of the reel (51) is parallel to the length direction of the prestressed tendon (11). The waterproof film (52) is reeled on the reel (51). The two ends of the reel (51) are respectively located on two bosses (2) and span the strain gauge (3). The first driving member is used to drive the reel (51) to move around the boss (2) to drive the waterproof film (52) to surround and be sleeved on the boss (2) to seal the strain gauge (3).

3. The device for measuring the effective prestress of a prestressed beam according to claim 2, characterized in that: The mounting plate (1) is provided with an annular groove (7) on the surface facing the strain gauge (3); the boss (2) is fixedly arranged in the middle of the annular groove (7); mounting seats (8) are provided at both ends of the winding shaft (51); the winding shaft (51) is rotatably arranged on the mounting seats (8); the mounting seats (8) are slidably arranged on the side walls of the annular groove (7); the first driving member includes a driving ring (53), a driving gear (54) and a driving motor (55); the driving ring (53) is rotatably arranged in the annular groove (7); the mounting seats (8) are fixedly arranged The inner ring of the driving ring (53) is provided with a toothed section (56), and the toothed section (56) is located on one side of the driving ring (53). The driving motor (55) is embedded in the mounting plate (1), and the driving gear (54) is provided on the output shaft of the driving motor (55) and meshes with the toothed section (56). The enclosing member (5) also includes a compensating member, and the compensating member is used to drive the waterproof film (52) rolled up on the reel (51) to abut against the boss (2) during the process of the waterproof film (52) being sheathed on the boss (2).

4. The device for measuring the effective prestress of a prestressed beam according to claim 3, characterized in that: The compensating member includes a first spring (57) and a telescopic tube (58), the mounting seat (8) includes a fixed seat (81) and a sliding seat (82), the fixed seat (81) is fixedly arranged on the inner side of the driving ring (53), the winding shaft (51) is rotatably arranged on the side wall of the sliding seat (82), the sliding seat (82) is located on the fixed seat (81) and is slidably arranged on the fixed seat (81), the telescopic tube (58) is fixedly arranged between the fixed seat (81) and the sliding seat (82), the first spring (57) is sleeved on the telescopic tube (58) and is used to drive the sliding seat (82) to slide toward the boss (2) to drive the waterproof film (52) to abut the boss (2).

5. The device for measuring the effective prestress of a prestressed beam according to claim 4, characterized in that: The enclosing member (5) further comprises a sealing member, which comprises a glue coating roller (59), a glue coating groove (510) and a second driving member. The glue coating groove (510) is arranged on the sliding seat (82), and the opening direction of the glue coating groove (510) faces the waterproof film (52). The glue coating roller (59) is rotatably arranged in the glue coating groove (510) and abuts against the outside of the waterproof film (52). The second driving member is used to drive the glue coating groove (510) to move toward the winding shaft (51) so that the glue coating roller (59) abuts against the outside of the waterproof film (52).

6. The device for measuring the effective prestress of a prestressed beam according to claim 5, characterized in that: The glue coating roller (59) spans the end of the waterproof film (52) on the reel (51).

7. The device for measuring the effective prestress of a prestressed beam according to claim 1, characterized in that: The dehumidifying element (6) comprises an air pipe (61) and an air valve (62). The air pipe (61) passes through the boss (2) and the mounting plate (1) and moves out of the prestressed beam along the direction of the prestressed tendons (11). The air valve (62) is arranged on the air pipe (61). The other end of the air pipe (61) is used to connect to an external air supply device to extract the moist air between the waterproof film (52) and the boss (2) and discharge it through the air pipe (61).

8. The device for measuring the effective prestress of a prestressed beam according to claim 7, characterized in that: The outer ring of the boss (2) is provided with a sealing groove (9), and the sealing groove (9) is connected at both ends to form a ring. A connecting channel is provided in the boss (2), and the connecting channel is used to connect the sealing groove (9) and the air pipe (61). When the air supply device extracts moist air, the gas in the sealing groove (9) is extracted, and the waterproof film (52) is sucked into the sealing groove (9).

9. The device for measuring the effective prestress of a prestressed beam according to claim 7, characterized in that: The measuring device further comprises a support net (10) sleeved on the prestressed tendon (11), the support net (10) being convex, and the strain gauge (3) being located below the support net (10).

10. A method for measuring the effective prestress of a prestressed beam, using the device for measuring the effective prestress of a prestressed beam according to any one of claims 1 to 9, characterized in that: Also includes; S1: When the prestressed tendons (11) of the prestressed beam are erected, the mounting plate (1) and the boss (2) are mounted on the prestressed tendons (11). When the mounting plate (1) and the boss (2) are mounted, the mounting plate (1) and the boss (2) are passed through the prestressed tendons (11). After the mounting plate (1) and the boss (2) are sleeved on the prestressed tendons (11), the gap between the mounting plate (1) and the boss (2) and the prestressed tendons (11) is sealed. S2: Fix the strain gauge (3) on the prestressed tendon (11) and wrap it around the boss (2) through a waterproof film (52), so that the waterproof film (52) encloses and seals the strain gauge (3); S3: applying tensile stress to the prestressed tendon (11), and the prestress is fed back through the resistance value of the strain gauge (3); S4: When the waterproof film (52) is damaged due to stretching or long-term use, the driving motor (55) is started, the driving motor (55) drives the driving gear (54) and the driving ring (53) to rotate, and the driving ring (53) drives the reel (51) to rotate and the waterproof film (52) is again placed on the boss (2) to cover the damaged waterproof film (52) for a second time; S5: When the waterproof film (52) is covered for the second time, the glue coating roller (59) coats the waterproof glue on the outer side of the waterproof film (52) to seal the adjacent layers of waterproof films (52). Part of the glue penetrates through the edge of the waterproof film (52) to the inner side of the waterproof film (52) to seal the adjacent layers of waterproof films (52).

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