CN111665133A - FRP rib tensile load holding and testing device and operation method thereof - Google Patents
FRP rib tensile load holding and testing device and operation method thereof Download PDFInfo
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- CN111665133A CN111665133A CN202010586675.4A CN202010586675A CN111665133A CN 111665133 A CN111665133 A CN 111665133A CN 202010586675 A CN202010586675 A CN 202010586675A CN 111665133 A CN111665133 A CN 111665133A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/06—Special adaptations of indicating or recording means
- G01N3/066—Special adaptations of indicating or recording means with electrical indicating or recording means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0017—Tensile
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/006—Crack, flaws, fracture or rupture
- G01N2203/0067—Fracture or rupture
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/022—Environment of the test
- G01N2203/0236—Other environments
- G01N2203/024—Corrosive
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/0617—Electrical or magnetic indicating, recording or sensing means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0676—Force, weight, load, energy, speed or acceleration
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0682—Spatial dimension, e.g. length, area, angle
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Abstract
The FRP bar tension load holding and testing device and the operation method thereof are characterized in that two ends of a twisted steel bar respectively penetrate through steel plates, and the inner side of the twisted steel bar corresponding to the steel plates is screwed with a finish rolling nut; the two ends of the FRP rib are respectively connected with the connecting rods through the connecting sleeves, the end parts of the two connecting rods are respectively fixed with a spherical hinge, and the two steel plates are respectively provided with a groove in which the corresponding spherical hinge is arranged so as to facilitate the rotation of the spherical hinge; the outer surface of one of the connecting sleeves is pasted with a strain gauge, the middle part of the FRP rib is also pasted with a strain gauge, and the two strain gauges are respectively connected with a resistance strain gauge through connecting wires. The tension load-holding device applies load by screwing the finish rolling nut by hand, and slightly rotates the finish rolling nut to realize fine adjustment of the load. The tension testing device applies a load by manually operating a feed-through puller. The load value is measured by using the connecting sleeve pasted with the strain gauge as a load sensor. The sleeve load holding device is simple to operate and can effectively keep tension.
Description
Technical Field
The invention belongs to the technical field of civil engineering test, and particularly relates to a FRP rib tensile load holding and testing device and an operation method thereof.
Background
The Fiber Reinforced Plastic (FRP) has the advantages of light weight, high strength, fatigue resistance, corrosion resistance, designability, easy processing and the like, and can replace steel to reinforce a concrete structure.
The FRP is a novel composite material prepared by taking continuous fibers as a reinforcement and polymer resin as a matrix through the processes of soaking, curing and the like. FRP consists of three parts: continuous fibers, resin matrix, and fiber/resin interface. Wherein, the continuous fibers are uniformly dispersed in the resin matrix, and the resin matrix is in linkage and synergistic stress. The pultrusion process of the FRP rib is to obtain an FRP rib product by sequentially carrying out the steps of gum dipping, surface treatment, preforming, curing molding, cutting and the like on a continuous fiber yarn bundle under the action of the pulling force of a tractor. The FRP reinforcement is often applied to prestressed reinforcements, and the stress relaxation generated by the FRP reinforcement can influence the prestress of the reinforcement, so that the bearing capacity of a building structure is influenced. The method for measuring the basic mechanical property of the FRP rib accurately, particularly the mechanical property of the rib in an erosion environment is the basis for applying the FRP rib to the civil engineering construction field. At present, most of related researches on the durability of FRP ribs are to place the ribs in an erosion environment for a period of time and then directly perform mechanical property tests, and few related researches on the durability of the FRP ribs in an actual erosion environment service state (coupling effect of load and the erosion service environment) are performed. On the basis of mastering the short-term performance of the FRP ribs and the reinforced concrete structure thereof, the long-term durability of the FRP ribs and the reinforced concrete structure under a typical application environment needs to be further defined, so that the safety, the reasonability and the large-scale application of the FRP ribs are guaranteed. Therefore, development and application of the FRP rib test device based on durability have important practical value.
Disclosure of Invention
The invention provides a device for testing the tensile property of an FRP (fiber reinforced Plastic) bar and an operation method thereof aiming at researching the tensile property of the FRP bar, and aims to realize the load holding of the FRP bar in an erosion service environment so as to measure the durability, mainly the tensile mechanical property, of the FRP bar under the action of the erosion environment. The invention uses a more novel, simple and rapid device to realize the tension holding load of the FRP rib. The whole device is placed in an erosion environment, the FRP rib materials are in a load and erosion environment coupling action state, and the actual erosion environment service stress state is simulated.
The invention comprises two devices, one is a FRP rib tension load-holding device, and the other is a FRP rib tension performance testing device. The sleeve load holding device is simple to operate and can effectively keep tension.
In order to realize the purpose, the device of the invention is divided into two steps of load holding and testing, and adopts the following technical scheme:
the FRP rib tension load-holding and testing device is characterized by comprising an FRP rib, two connecting sleeves, two connecting rods, four threaded steel bars and two steel plates, wherein the threaded steel bars are horizontally arranged in parallel, two ends of the threaded steel bars respectively penetrate through the steel plates, and the threaded steel bars are screwed with finish rolling nuts on the inner side threads of the corresponding steel plates; the two ends of the FRP rib are respectively connected with the connecting rod through the connecting sleeve, and the FRP rib is connected with the bonding sleeve through the internal filling structural adhesive; the end parts of the two connecting rods are respectively fixed with a spherical hinge, and the two steel plates are respectively provided with a groove internally provided with a corresponding spherical hinge so as to facilitate the rotation of the spherical hinges; the outer surface of one of the connecting sleeves is pasted with a strain gauge, the middle part of the FRP rib is also pasted with a strain gauge, and the two strain gauges are respectively connected with a resistance strain gauge through connecting wires.
Furthermore, the twisted steel is a prestressed finish-rolled twisted steel, and the steel plate is a variable cross-section steel plate; and the two ends of the FRP ribs are fixedly connected with bonding sleeves, and the connecting sleeves are respectively screwed with the corresponding bonding sleeves and the connecting rods in a threaded manner.
Furthermore, a reinforcing circular steel tube is fixedly connected to the variable cross-section steel plate and is sleeved on the end portion of the corresponding connecting rod.
Furthermore, four rectangular stiffening rib steel plates are fixedly connected to the variable cross-section steel plates and are evenly distributed along the circumferential direction of the reinforced circular steel tube, and the reinforced circular steel tube and the variable cross-section steel plates are supported in four directions.
Furthermore, the finish rolling nuts are tightly attached to the inner side ends of the corresponding variable cross-section steel plates, steel gaskets are arranged between the finish rolling nuts and the corresponding variable cross-section steel plates, and the four finish rolling nuts on the same side are rotated to apply loads, so that a tensile load test is completed. Specifically, under continuous loading:
the four finish rolling nuts on the inner side of the right-end variable cross-section steel plate are simultaneously rotated to apply an outward force to the variable cross-section steel plate, so that the connecting rod, the connecting sleeve and the bonding sleeve are sequentially driven to bear force, the FRP rib is pulled, and meanwhile, the left-end variable cross-section steel plate limits the movement of the left-side bonding sleeve, so that the load holding of the FRP rib is realized;
slightly rotating the finish rolling nut to realize fine adjustment of load; in the test process, observing the numerical value of the resistance strain gauge until the designed load holding value is reached; in the load holding process, the parallelism of the left variable cross-section steel plate surface and the right variable cross-section steel plate surface is ensured.
Furthermore, two square steel plates which are penetrated by the threaded steel bars are arranged between the connecting sleeve on the right side and the variable cross-section steel plate, a punching drawing instrument is arranged between the two square steel plates and penetrates through the connecting rod, the square steel plate on the right side supports against the four rectangular stiffening rib steel plates, and the tension test is completed by operating the punching drawing instrument to apply load. Specifically, during testing:
loading is carried out by using a feed-through drawing instrument, the feed-through drawing instrument pushes a square steel plate on the right side of the feed-through drawing instrument to apply an outward force, the pulling force is transmitted to the FRP rib through a spherical hinge, a connecting rod, a connecting sleeve and a bonding sleeve on the right end of the device respectively, and meanwhile, the spherical hinge on the left end limits the movement of the bonding sleeve on the left end, so that the pulling force is applied to the FRP rib until the FRP rib is broken; the tensile force is measured by a connecting sleeve connecting resistance strain gauge which is also used as a load sensor, and then the tensile strength of the FRP rib is calculated.
The tension load-holding device provided by the invention not only can apply continuous load to the FRP rib material, but also can measure the stress relaxation of the FRP rib material in the load-holding process, because the long-term load holding can cause the stress relaxation of the FRP rib material, thereby further causing the prestress loss.
The FRP rib tension testing device provided by the invention is additionally provided with a square steel plate and a straight-through drawing instrument on the basis of a load holding device. The specific modifications are as follows: a square steel plate is additionally arranged between the connecting sleeve and the rectangular stiffening rib steel plate, and a finish rolling nut is screwed on the left side of the square steel plate to provide support for the drawing instrument. The straight-through drawing instrument is placed on the right side of the square steel plate, the square steel plate is placed at the right end to support the rectangular stiffening rib steel plate (the stiffening rib steel plate is set to be rectangular and can be conveniently supported by the square steel plate), and the steel washer and the finish rolling nut on the inner side of the variable cross-section steel plate are removed.
The steel plate is made of stainless steel; the tension load-holding device applies load by screwing the finish rolling nut by hand, and slightly rotates the finish rolling nut to realize fine adjustment of the load. The tension testing device applies a load by manually operating a feed-through puller. The load value is measured by using the connecting sleeve pasted with the strain gauge as a load sensor.
The invention has the beneficial effects that:
1. the invention provides an FRP rib load holding and testing device which is simple in structure and easy to operate;
2. the load holding device is used for stably pushing the steel plate to apply tension to the FRP rib by manually screwing the nut, the spherical hinge at the end part can rotate when encountering eccentric force so as to avoid adverse influence on a test caused by eccentric tension, ensure that axial tension is applied to the FRP rib and realize the long-term load holding target, and can also be used for measuring the prestress loss in the load holding process of the FRP rib, and the later-stage testing device carries out loading by using a straight-through drawing instrument;
3. the load holding device can apply continuous load to the test piece without using a reaction frame, and the connecting sleeve adhered with the strain gauge is also used as a load sensor, so that the space occupied by the loading device and the test cost are greatly reduced;
4. the load holding and testing device is made of corrosion-resistant materials and is not easy to rust; after the test piece is kept loaded, the test piece is placed into an erosion environment simulation device (such as a freeze-thaw test box, a carbonization box, a chloride salt and sulfate erosion solution environment and the like) so that the test piece is in a state of coupling action of load and an erosion environment, and the service stress state of the erosion environment is simulated.
Drawings
FIG. 1 is a schematic view of a FRP rib tension holding device in example 1 of the present invention;
FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;
FIG. 3 is a schematic view of a steel washer;
FIG. 4 is a schematic view of a finish rolling nut;
FIG. 5 is a schematic view of a FRP rib tension test apparatus in example 2 of the present invention;
FIG. 6 is a schematic view of a square steel plate;
FIG. 7 is a cross-sectional view taken along line B-B of FIG. 5;
in the figure: 1 is the FRP muscle, 2 is the bonding sleeve, 3 is the connecting sleeve, 4 is the connecting rod, 5 is reinforcing circular steel tube, 6 is rectangle stiffening rib steel sheet, 7 is the ball pivot, 8 is prestressing force finish rolling twisted steel, 9 is the steel washer, 10 is the finish rolling nut, 11 is the foil gage, 12 is resistance strain gauge, 13 is connecting wire, 14 is the square steel sheet, 15 is the punching type and draws the appearance.
Detailed Description
Example 1
As shown in figure 1, the device for testing the tensile load of the FRP tendon is characterized by comprising an FRP tendon 1, a bonding sleeve 2, a connecting sleeve 3, a connecting rod 4, a reinforced circular steel tube 5, a rectangular stiffening rib steel plate 6, a spherical hinge 7, a prestressed finish-rolled threaded steel bar 8, a steel washer 9, a finish-rolled nut 10, a strain gauge 11, a resistance strain gauge 12 and a connecting wire 13. The sleeve is divided into a bonding sleeve with external threads and a connecting sleeve with internal threads, and the two bonding sleeves are fixed at two ends of the FRP rib respectively through glue filling.
For the right half part of the device, the connecting sleeve 3 is provided with internal threads and has a smooth outer surface, the bonding sleeve 2 and the connecting rod 4 are connected together through the connecting sleeve 3, the connecting rod is made of steel and is integrated with a spherical hinge at the end part of the right half part; as shown in fig. 2, the reinforced circular steel tube 5 is fixed with the variable cross-section steel plate at the end of the spherical hinge 7, and is sleeved on the connecting rod 4 with a certain distance from the connecting rod 4; the four rectangular stiffening rib steel plates are used for connecting the reinforced circular steel tubes and the variable cross-section steel plates in four directions so as to ensure that the groove positions formed by the spherical hinges are not locally damaged, and the reinforced circular steel tubes and the connecting sleeves are separated by a certain distance so as to ensure that the connection can freely rotate (the spherical hinges 7 can rotate under the action of eccentric force); the variable cross-section steel plate is a part of the spherical hinge, four reserved holes are arranged at four corners, and the variable cross-section steel plate is designed to be heavy due to the fact that the thickness of the steel plate is large.
Further, the connecting rod is of sufficient length for subsequent testing; the end part of the spherical hinge is a variable cross-section steel plate with four corners provided with round reserved holes; the middle part of the variable cross-section steel plate is reserved with a groove to be in rotary contact with the spherical hinge.
The left half of this device is identical to the right half of the device described above.
Four pre-stressed finish rolling twisted steel bars 8 respectively penetrate reserved holes at four corners of the left variable cross-section steel plate and the right variable cross-section steel plate; as shown in fig. 3, the steel washer 9 is circular and is arranged between the variable cross-section steel plate and the finish rolling nut 10, the inner diameter of the steel washer is slightly larger than the diameter of the prestressed finish rolling twisted steel 8, and the outer diameter of the steel washer is larger than the diameter of the circumscribed circle of the finish rolling nut 10; the finish rolling nut 10 connects the prestress finish rolling twisted steel 8 with the left and right variable cross-section steel plates, and the finish rolling nut 10 is a hexagon nut.
The two connecting rods 4 are respectively integrated with the spherical hinges 7 at the left end and the right end. A certain distance is reserved between the reinforcing circular steel tube 5 and the connecting sleeve 3. The preformed hole on the variable cross-section steel plate at the end part of the spherical hinge 7 is a circular through hole, and the diameter of the preformed hole is larger than that of the prestress finish rolling twisted steel 8.
And furthermore, the number of the strain gauges is two, one strain gauge is attached to the outer surface of the right half part of the connecting sleeve, the connecting sleeve is connected with the bonding sleeve and the connecting rod, the strain gauge is attached to the strain gauge and serves as a load sensor, and the strain gauge is connected with the resistance strain gauge through a connecting lead. The other one is pasted in the middle of the FRP rib material and is also used as a load sensor, and the strain gauge is connected with the resistance strain gauge through a connecting wire. When the load is kept, the connecting sleeve 3 is pulled, the tensile strain can be displayed by the aid of the resistance strain gauge 12, the tensile strain is converted into the tensile force applied to the connecting sleeve 3 through calculation, and the tensile force applied to the connecting sleeve 3 is the continuous load applied to the FRP rib.
The device is made of corrosion-resistant stainless steel materials, and the durability of the device is not reduced under the action of an erosion environment.
FRP muscle is drawn and is held lotus test device, the load that lasts at normal use state is realized through four finish rolling nuts 10 of rotatory right-hand member variable cross section steel sheet inboard simultaneously, exert outside power to the variable cross section steel sheet through rotatory finish rolling nut 10, drive connecting rod 4, connecting sleeve 3, bonding sleeve 2 atress in proper order, make FRP muscle 1 draw, the left end variable cross section steel sheet restriction left side bonding sleeve 2's removal simultaneously, and then the realization is held the lotus to FRP muscle 1. The fine adjustment of the load is achieved by slightly rotating the finish rolling nut 10. During the test, the resistance strain gauge 12 values were observed until the designed holding value was reached. In the load holding process, the parallelism of the left variable cross-section steel plate surface and the right variable cross-section steel plate surface is ensured.
In addition, the FRP reinforcement tensile load holding test device can also test the stress relaxation generated by the FRP reinforcement 1 in the test process, and in the FRP reinforcement 1, the FRP reinforcement 1 can generate the stress relaxation to cause the prestress loss, and the load value of the resistance strain gauge 12 connected to the resistance strain gage 11 on the FRP reinforcement 1 can change (originally, the load value of the resistance strain gauge 12 is the same as that of the resistance strain gauge 12 at the right end), and at this time, the load value needs to be recovered by screwing the finish rolling nut 10 at the tensile end of the device by hand.
Then, the FRP ribs are loaded and then placed into an erosion environment simulation device (such as a freeze-thaw test box, a carbonization box, a chloride salt and sulfate erosion solution environment and the like), and after reaching a preset time period, the FRP ribs are taken out and used for the tension testing device in the figure 5.
Example 2
As shown in FIG. 5, the FRP tendon tension testing device comprises an FRP tendon 1, a bonding sleeve 2, a connecting sleeve 3, a connecting rod 4, a reinforced circular steel tube 5, a rectangular stiffening rib steel plate 6, a spherical hinge 7, a prestress finish rolling threaded steel bar 8, a steel washer 9, a finish rolling nut 10, a strain gauge 11, a resistance strain gauge 12, a connecting wire 13, a square steel plate 14 and a straight-through drawing gauge 15.
And taking out the load holding device in the erosion environment simulation device, and adding a square steel plate 14 and a straight-through drawing instrument 15 on the basis of the load holding device. As shown in fig. 6, two more square steel plates 14 are added, one of which is placed between the right half connecting sleeve 3 and the rectangular stiffener steel plate 6, the left side of which is fixed by a steel washer 9 and a finish rolling nut 10, and the other of which is arranged on the right side of the straight-through drawing instrument 15 for supporting the rectangular stiffener steel plate 6; the straight-through drawing instrument 15 is arranged between the two square steel plates 14 and is used for applying tension; as shown in fig. 7, the steel washer 9 and the finish rolling nut 10 inside the variable cross-section steel plate are removed.
Further, the square steel plate 14 is provided with five circular preformed holes at four corners and the center, respectively, the diameter of the preformed holes at the four corners is larger than that of the prestressed finish-rolled twisted steel bar 8, and the diameter of the preformed hole at the center is larger than that of the connecting rod 4.
The FRP muscle is drawn testing arrangement, during the test, utilize the punching to draw appearance 15 and load, the punching is drawn appearance 15 and is promoted the square steel plate 14 application on its right side and outwards exert force, and the pulling force is passed through the ball pivot 7 of device right-hand member, connecting rod 4, connecting sleeve 3, bonding sleeve 2 respectively and is given FRP muscle 1, and the ball pivot 7 of left end has restricted the removal that the left end bonds sleeve 2 simultaneously, and then realizes applying the pulling force to FRP muscle 1, is broken until the FRP muscle. The tensile force is measured by connecting the connecting sleeve 3 which is also used as a load sensor with the resistance strain gauge 12, and then the tensile strength of the FRP rib can be calculated.
Finally, the present invention is not limited to the above-described embodiments, and many modifications may be made on the basis of the essence of the present invention, and all modifications directly conceivable by those skilled in the art on the basis of the contents of the present invention are to be considered as the scope of protection of the present invention.
Claims (8)
- The FRP rib tension load-holding and testing device is characterized by comprising an FRP rib, two connecting sleeves, two connecting rods, four horizontal twisted steel bars arranged in parallel and two steel plates, wherein two ends of the twisted steel bars respectively penetrate through the steel plates, and the inner threads of the twisted steel bars corresponding to the steel plates are screwed with finish rolling nuts; the two ends of the FRP rib are respectively connected with the connecting rod through the connecting sleeve, and the FRP rib is connected with the bonding sleeve through the internal filling structural adhesive; the end parts of the two connecting rods are respectively fixed with a spherical hinge, and the two steel plates are respectively provided with a groove internally provided with a corresponding spherical hinge so as to facilitate the rotation of the spherical hinges; the outer surface of one of the connecting sleeves is pasted with a strain gauge, the middle part of the FRP rib is also pasted with a strain gauge, and the two strain gauges are respectively connected with a resistance strain gauge through connecting wires.
- 2. The FRP bar tension load-holding and testing device as claimed in claim 1, wherein the deformed bars are pre-stressed finish-rolled deformed bars, and the steel plates are variable cross-section steel plates; and the two ends of the FRP ribs are fixedly connected with bonding sleeves, and the connecting sleeves are respectively screwed with the corresponding bonding sleeves and the connecting rods in a threaded manner.
- 3. The FRP rib tension load and test device as claimed in claim 2, wherein the variable cross-section steel plate is fixedly connected with a round reinforcing steel pipe, and the round reinforcing steel pipe is sleeved on the end part of the corresponding connecting rod.
- 4. The FRP rib tensile loading and testing device as claimed in claim 3, wherein four rectangular stiffening rib steel plates are fixedly connected to the variable cross-section steel plates, and are uniformly distributed along the circumferential direction of the round reinforcing steel tube for supporting the round reinforcing steel tube and the variable cross-section steel plates in four directions.
- 5. The FRP bar tensile load and test device according to claim 4, wherein the finish rolling nuts are tightly attached to the inner ends of the corresponding variable cross-section steel plates, steel washers are arranged between the finish rolling nuts and the corresponding variable cross-section steel plates, and the tensile load test is completed by rotating four finish rolling nuts on the same side to apply loads.
- 6. The FRP rib tensile load and test device according to claim 4, wherein two square steel plates penetrated by the deformed steel bar are arranged between the right connecting sleeve and the variable cross-section steel plate, a center-penetrating drawing instrument is arranged between the two square steel plates and penetrates through the connecting rod, the right square steel plate is abutted against the four rectangular stiffening rib steel plates, and the tensile test is completed by operating the center-penetrating drawing instrument to apply load.
- 7. The method for operating the FRP rib tension holding and testing device according to claim 5, wherein when the load is continuously applied:the four finish rolling nuts on the inner side of the right-end variable cross-section steel plate are simultaneously rotated to apply an outward force to the variable cross-section steel plate, so that the connecting rod, the connecting sleeve and the bonding sleeve are sequentially driven to bear force, the FRP rib is pulled, and meanwhile, the left-end variable cross-section steel plate limits the movement of the left-side bonding sleeve, so that the load holding of the FRP rib is realized;slightly rotating the finish rolling nut to realize fine adjustment of load; in the test process, observing the numerical value of the resistance strain gauge until the designed load holding value is reached; in the load holding process, the parallelism of the left variable cross-section steel plate surface and the right variable cross-section steel plate surface is ensured.
- 8. The method for operating an FRP rib tension holding and testing device according to claim 6, wherein during testing:loading is carried out by using a feed-through drawing instrument, the feed-through drawing instrument pushes a square steel plate on the right side of the feed-through drawing instrument to apply an outward force, the pulling force is transmitted to the FRP rib through a spherical hinge, a connecting rod, a connecting sleeve and a bonding sleeve on the right end of the device respectively, and meanwhile, the spherical hinge on the left end limits the movement of the bonding sleeve on the left end, so that the pulling force is applied to the FRP rib until the FRP rib is broken; the tensile force is measured by a connecting sleeve connecting resistance strain gauge which is also used as a load sensor, and then the tensile strength of the FRP rib is calculated.
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Application publication date: 20200915 |