CN111707541B - Single-shaft tension loading and testing device for concrete and application method thereof - Google Patents
Single-shaft tension loading and testing device for concrete and application method thereof Download PDFInfo
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- CN111707541B CN111707541B CN202010586686.2A CN202010586686A CN111707541B CN 111707541 B CN111707541 B CN 111707541B CN 202010586686 A CN202010586686 A CN 202010586686A CN 111707541 B CN111707541 B CN 111707541B
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
The single-shaft tensile load holding and testing device for the concrete and the using method thereof do not need to adopt an independent load sensor, and the method of sticking the resistance strain gauge by adopting the connecting sleeve with the internal threads and the external smooth circle is adopted to enable the connecting sleeve to be used as the load sensor, so that the testing device is simplified, and the cost problem that a large number of load sensors are occupied by long-term load holding is reduced. The invention realizes the application of axial tension to the concrete test block by simultaneously rotating the second specification of four finish rolling nuts close to one side of the upper spherical hinge. The connecting sleeve attached with the strain gauge is also used as a load sensor to obtain a load, and the second specification of the finish rolling nut is slightly rotated to realize fine adjustment of the load. For the concrete single-shaft tension testing device, a square steel plate and a through-type drawing instrument are added on the basis of a load holding device. The invention combines the single-shaft tension load holding and testing device of the concrete into a whole, has simple operation and can provide stable and effective continuous load.
Description
Technical Field
The invention belongs to the field of civil engineering, and particularly relates to a device for testing uniaxial tensile load of concrete and a use method thereof, which are particularly suitable for researching the durability test of a uniaxial tensile test piece of concrete under the coupling action of load and erosion environment.
Background
It is well known that concrete is one of the most widely used building materials in current engineering construction, compression strength being its most prominent feature, while there is less concern about its tensile strength. Therefore, the tensile strength of the concrete is mainly born by the concrete in the modern structure, and the tensile strength of the concrete is generally only 1/17-1/8 of the compressive strength, and the tensile strength of the concrete can be achieved by a small load, so that the tensile strength of the concrete is usually ignored in the structural design and the tensile strength of the structure is born by the steel bars. In some structures, such as fully prestressed concrete structures, tensile stresses are not allowed, while in partially prestressed structures tensile stresses are allowed.
The tensile strength and deformation of concrete are one of the most important basic properties of concrete. It is an important component for researching strength theory and failure mechanism of concrete and is an important factor affecting cracking, deformation and durability of concrete structure. The tensile strength controls the whole process of the occurrence and development of cracks in the concrete and other properties related to the tensile strength, such as elastic modulus, rigidity, steel bar bond strength, durability of the concrete and the like, and in addition, the tensile strength is also a main factor influencing the shearing resistance of the concrete and is an important parameter for establishing a multi-axis failure criterion of the concrete. In recent years, along with the construction of a large number of high-rise buildings and large-span bridge projects, the proportion of high-performance concrete used in modern structures is higher and higher, and one main characteristic of the high-performance concrete is high durability, while the surfaces of realistic structures such as bridges, crane beams, pavements, ocean platforms and the like are provided with a plurality of macroscopic cracks, so that the durability of the high-performance concrete is seriously affected, and the safety reliability and the service life of the high-performance concrete are ensured. The development of concrete cracks is mainly related to the tensile strength, so that the research on the tensile property of concrete has very important significance.
The test research on the tensile strength of concrete is only in an initial stage for a long time, and the concrete has extremely high discreteness, so that the tensile strength of the concrete is not known completely after the concrete tensile test equipment. 20. After 60 th century, researchers developed a series of concrete tensile test devices to measure the full curve of the tensile stress and strain of concrete, but the test devices adopted by each researcher were different. In the past researches, the long-term performance of the concrete uniaxial tension test piece under continuous load, especially the durability under the erosion service environment (coupling effect of load and erosion environment) is less, and in the test process, the concrete uniaxial tension is realized by a physical centering method, so that the operation is complex, and the centering condition is not well controlled. Therefore, no known effective method exists at present, if a test piece cannot be centered, the test piece breaks quickly once loaded, the test fails, and the durability test has strict requirements on environmental conditions such as test temperature, humidity and the like; in addition, the operation process of the test is very complex, and the requirements on test equipment, a data acquisition system, test piece performance and test conditions are very high. In the prior art, two sets of test devices are often needed for a load holding device and a test device for a concrete uniaxial tension test under the long-term action of load, so that the test is not convenient enough. Therefore, a set of concrete uniaxial tension load holding and testing device needs to be established as early as possible.
Disclosure of Invention
Aiming at the problems that a traditional concrete tension test device is used, a concrete test piece is difficult to center and the test operation process is complex, the invention provides a single-shaft tension load holding and testing device for concrete and a using method thereof.
The technical scheme of the invention is as follows:
the single-shaft tension loading and testing device for the concrete is characterized by comprising a concrete test block, a top steel plate, a bottom steel plate, four second prestressed finish rolling screw-thread reinforcing steel bars, two spherical hinges, a common connecting rod, a lengthened connecting rod and two square anchor plates; the top steel plate and the bottom steel plate respectively pass through four second prestressed finish rolling deformed bars and are respectively arranged at the upper part and the lower part of the second prestressed finish rolling deformed bars in parallel; the top steel plate and the bottom steel plate are respectively in rotary contact with the spherical hinge, the lengthened connecting rod is fixedly connected with the spherical hinge positioned at the top into a whole, and the common connecting rod is fixedly connected with the spherical hinge positioned at the bottom into a whole;
the two square anchor plates are fixedly connected with the top end and the bottom end of the concrete test block through four corners of the two square anchor plates respectively, and the middle parts of the two square anchor plates are respectively fixed with first prestressed finish rolling screw-thread steel bars; the end parts of the two first prestressed finish rolling deformed bars are respectively screwed with the connecting sleeves, and the two connecting sleeves are respectively screwed with the common connecting rod and the lengthened connecting rod; and the single-shaft tension loading and testing of the concrete are completed by upwards driving the first prestressed finish rolling twisted steel on the upper part to bear force.
Further, four finish rolling screw thread reinforcing bars are prefabricated at the top end and the bottom end of the concrete test block respectively, and are exposed for a certain length; four corners of the square anchor plate are respectively provided with a preformed hole, four finish rolling threaded reinforcing bars penetrate through the four preformed holes of the corresponding square anchor plate, the finish rolling threaded reinforcing bars are screwed into finish rolling nuts, and the two square anchor plates are connected with the concrete test block into a whole.
Furthermore, the bottom steel plate and the top steel plate are all variable cross-section steel plates.
Further, four finish rolling nuts are arranged on the bottom steel plate and are screwed with corresponding second prestress finish rolling screw-thread steel bars, and steel washers are arranged between the finish rolling nuts and the bottom steel plate.
Further, the top steel plate and the bottom steel plate are respectively fixed with a reinforced circular steel tube, and the two reinforced circular steel tubes are respectively sleeved on the lengthened connecting rod and the common connecting rod;
four rectangular stiffening rib steel plates are uniformly arranged in the circumferential direction of the two reinforced round steel pipes and fixedly connected with corresponding steel plates, and are used for connecting the reinforced round steel pipes with the corresponding steel plates in four directions so as to ensure that the spherical hinge is not damaged locally.
Further, the outer surface of the connecting sleeve at the upper part is pasted with a strain gauge which is also used as a load sensor and is connected with the resistance strain gauge through a connecting wire.
Further, four finish rolling nuts are arranged at the bottom of the top steel plate and are screwed with corresponding second prestress finish rolling screw-thread steel bars, and a steel gasket is arranged between each finish rolling nut and the corresponding top steel plate. Specifically, a uniaxial tension and load test of concrete:
by simultaneously rotating four finish rolling nuts at the bottom of the top steel plate, applying an outward force to the top steel plate, sequentially driving the lengthened connecting rod, the connecting sleeve and the first prestressed finish rolling screw-thread steel bar to bear force, and further enabling the concrete test block to be pulled; meanwhile, the bottom steel plate limits the movement of the first prestressed finish rolling threaded steel bar and the square anchor plate, so that the load holding of the concrete test block is realized; the continuous load is obtained by using a connecting sleeve with a strain gauge as a load sensor, and fine adjustment of the load is realized by slightly rotating a finish rolling nut at the bottom of the top steel plate; in the loading process, the parallelism of the upper and lower variable-section steel plate surfaces is ensured.
Further, two middle steel plates are arranged between the upper connecting sleeve and the upper rectangular stiffening rib steel plate, and penetrate through four second prestress finish rolling screw-thread steel bars respectively; the middle steel plate is positioned on the upper connecting sleeve, the top of the middle steel plate is used for supporting the through type drawing instrument, the through type drawing instrument is sleeved on the lengthened connecting rod, four finish rolling nuts are arranged at the bottom of the middle steel plate and are screwed with corresponding second prestress finish rolling screw steel bars, and a steel gasket is arranged between each finish rolling nut and each middle steel plate; the other middle steel plate is positioned at the top of the piercing-drawing instrument. Specifically, the uniaxial tension test of concrete:
during testing, the through-type drawing instrument applies upward force against the middle steel plate above the through-type drawing instrument, and the tensile force is respectively transmitted to the concrete test block through the spherical hinge at the upper end, the lengthened connecting rod, the connecting sleeve and the first prestressed finish-rolled screw reinforced bar; meanwhile, the spherical hinge at the bottom limits the movement of the first prestressed finish rolling screw-thread steel bar and the square anchor plate, so that the tensile force is applied to the concrete test block until the test piece is damaged; the tensile force is measured by the connecting sleeve which is also used as a load sensor, and then the tensile strength of the concrete can be calculated by applying a formula.
The invention does not need to adopt an independent load sensor, and adopts a method of sticking the resistance strain gauge by adopting the connecting sleeve with the internal thread and the external light circle, so that the resistance strain gauge can be used as the load sensor, the test device is simplified, and the cost problem that a large number of load sensors are occupied when long-term load holding is realized is solved. The sleeve holding device is simple to operate and can provide stable and effective continuous load. The invention combines the uniaxial tension load holding and testing device of the concrete into a whole, and the load holding test and testing of the uniaxial tension performance of the concrete under the long-term action of load do not need to be carried out by using the two devices, but the testing device is formed on the basis of the load holding device.
The steel plate is made of stainless steel; the invention realizes the application of axial tension to the concrete test block by simultaneously rotating the second specification of four finish rolling nuts close to one side of the upper spherical hinge. The connecting sleeve attached with the strain gauge is also used as a load sensor to obtain a load, and the second specification of the finish rolling nut is slightly rotated to realize fine adjustment of the load. For the concrete single-shaft tension testing device, a square steel plate and a through-type drawing instrument are added on the basis of a load holding device.
The invention has the beneficial effects that:
1. the invention provides a concrete single-shaft tension load holding and testing device which is simple in structure and easy to operate;
2. the load holding device can provide reliable and stable load for the concrete test block by screwing the finish rolling nut under the top steel plate, can meet the requirement of long-term loading, can ensure that the steel plate is stably pushed and axial tension is applied to the concrete test block when the spherical hinge at the end part rotates under the eccentric force, so as to avoid adverse effects on the test caused by eccentric tension;
3. the load holding device can apply continuous load to the test piece without a reaction frame, and the connecting sleeve attached with the strain gauge is used as a load sensor, so that the space occupied by the loading device is greatly reduced;
4. the invention can be used as a single-shaft tension and load-holding device of the concrete, and can form a single-shaft tension test device of the concrete through local modification;
5. the load holding and testing device is made of corrosion-resistant stainless steel materials, and is not easy to rust. Placing the test piece into an erosion environment simulation device (such as a freeze thawing test box, a carbonization box, a chloride and sulfate erosion solution environment and the like) after the test piece is loaded, enabling the test piece to be in a coupling action state of the load and the erosion environment, simulating a service stress state of the erosion environment, and testing the mechanical property and the durability of the test piece.
Drawings
FIG. 1 is a schematic diagram of a single-axis tensile load test device for concrete according to the invention;
FIG. 2 is a schematic view of a square anchor plate;
FIG. 3 is a cross-sectional view taken along line A-A of FIG. 1;
FIG. 4 is a schematic view of a steel washer;
FIG. 5 is a schematic diagram of a device for testing uniaxial tension of concrete according to the invention;
FIG. 6 is a cross-sectional view B-B of FIG. 5;
FIG. 7 is a schematic view of a square steel plate;
in the figure, 1 is a concrete test block, 2 is a finish rolling screw thread reinforcing steel bar, 3 is a square anchor plate, 4 is a first pre-stress finish rolling screw thread reinforcing steel bar specification (first pre-stress finish rolling screw thread reinforcing steel bar), 5 is a finish rolling nut specification, 6 is a connecting sleeve, 7 is a common connecting rod, 8 is an elongated connecting rod, 9 is a reinforced round steel pipe, 10 is a rectangular stiffening rib steel plate, 11 is a spherical hinge, 12 is a second pre-stress finish rolling screw thread reinforcing steel bar specification (second pre-stress finish rolling screw thread reinforcing steel bar), 13 is a steel washer, 14 is a second finish rolling nut specification, 15 is a strain gauge, 16 is a resistance strain gauge, 17 is a connecting wire, 18 is a square steel plate, and 19 is a through drawing gauge.
Detailed Description
The invention is further described with reference to the drawings and specific examples.
Example 1
As shown in fig. 1, the single-axis tension and load test device for concrete comprises a concrete test block 1, finish rolling screw steel bars 2, square anchor plates 3, a first pre-stress finish rolling screw steel bar specification 4, a first finish rolling nut specification 5, a connecting sleeve 6, a common connecting rod 7, a lengthened connecting rod 8, a reinforced round steel pipe 9, a rectangular stiffening rib steel plate 10, a spherical hinge 11, a second pre-stress finish rolling screw steel bar specification 12, a steel gasket 13, a second finish rolling screw steel bar specification 14, a strain gauge 15, a resistance strain gauge 16 and a connecting wire 17. The concrete test block 1 (120 mm multiplied by 400 mm) is nonstandard, the influence of reducing the end stress effect is considered, the tensile damage is guaranteed to occur in the middle part, the area of the middle part of a test piece is reduced, a self-made steel mould is adopted to finish pouring and forming of the test piece, after 24 hours, the mould is removed, and the test piece is placed into a standard curing chamber for curing; eight finish rolling twisted steel bars 2 (150 mm in length) are respectively embedded at two ends of a concrete test block so as to realize uniform axial tensile and stress distribution, provide enough anchoring strength and expose the same for a certain length, thereby facilitating test operation; the device is divided into an upper part and a lower part by a concrete test block 1 and a finish rolling twisted steel 2 pre-buried in the concrete test block.
For the upper half part of the device, as shown in fig. 2, the square anchor plate 3 is arranged at the end part of the concrete test block 1, four reserved holes are formed in four corners, and the center and the prestressed finish rolling screw thread steel bar specification one 4 are welded together to form a whole; the finish rolling nut specification one 5 is provided with four corners of the square anchor plate 3 and is used for connecting the finish rolling deformed bar 2 with the square anchor plate 3, and then connecting the concrete test block 1 with the prestressed finish rolling deformed bar specification one 4. The connecting sleeve 6 is provided with internal threads and has a smooth outer surface, and the pre-stress finish-rolled screw-thread reinforcing steel bar with the specification I4 and the lengthened connecting rod 8 are connected together through the connecting sleeve 6; the reinforced round steel pipe 9 is fixed with a variable cross section steel plate at the end part of the spherical hinge 11 and sleeved on the lengthened connecting rod 8, and a certain distance is reserved between the reinforced round steel pipe and the lengthened connecting rod 8.
As shown in fig. 3, the rectangular stiffening rib steel plate 10 is used for connecting the reinforced round steel pipe 9 and the spherical hinge 11 in four directions so as to prevent the spherical hinge from being locally damaged; the spherical hinge 11 rotates under 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 variable in order to avoid heavy and heavy steel plate thickness.
For the lower half of the device, the elongated connecting rod 8 in the upper half is replaced by a common connecting rod 7, the rest being the same as for the upper half of the device described above.
Four pre-stress finish rolling deformed bar specifications II 12 respectively penetrate through pre-reserved holes in four corners of the upper variable cross-section steel plate and the lower variable cross-section steel plate.
As shown in fig. 4, the steel washer 13 is circular, and is disposed between the variable cross-section steel plate and the finish-rolled nut gauge two 14, the inner diameter is slightly larger than the diameter of the prestressed finish-rolled twisted steel gauge two 12, and the outer diameter is larger than the circumscribed circle diameter of the finish-rolled nut gauge two 14; and the finish rolling nut specification II 14 is used for connecting the prestressed finish rolling twisted steel specification II 12 with the upper and lower variable cross-section steel plates.
Further, the diameter of the reserved hole on the square anchor plate 3 is larger than that of the finish rolling deformed bar 2.
The diameter of the first pre-stress finish rolling deformed bar specification 4 is larger than that of the second pre-stress finish rolling deformed bar specification 12.
And the first finish rolling nut specification 5 and the second finish rolling nut specification 14 are hexagonal nuts.
The lengthened connecting rod 8 and the common connecting rod 7 are made of steel and are respectively integrated with spherical hinges 11 at the upper end and the lower end.
A certain distance is reserved between the reinforced round steel pipe 9 and the connecting sleeve 6.
The preformed hole on the variable cross section steel plate of spherical hinge 11 tip is circular through-hole, and the diameter of preformed hole is greater than the diameter of prestressing force finish rolling deformed bar specification two 12, and the recess is reserved in variable cross section steel plate middle part in order to rotate with the spherical hinge and contact.
Still further, the surface of the connecting sleeve 6 of the upper half of the device is stuck with strain gauges 15 which also serve as load sensors. The strain gauge 15 is connected with the resistance strain gauge 16 through the connecting lead 17, the connecting sleeve 6 is pulled when the load is held, the magnitude of the tensile strain can be displayed by the resistance strain gauge 16, and the tensile force is converted into the tensile force born by the connecting sleeve 6 through calculation, namely the continuous load born by the concrete test block 1 at the connecting sleeve 6.
The device is made of corrosion-resistant stainless steel materials, and the durability is not reduced under the action of an erosion environment.
The utility model provides a concrete unipolar holds load test device, the continuous load in normal service condition is realized through four finish rolling nut specification second 14 of the inboard of rotatory upper end variable cross section steel sheet, exert outside force to the variable cross section steel sheet through rotatory finish rolling nut specification second 14, drive extension connecting rod 8 in proper order, connecting sleeve 6, the first 4 atress of prestressing force finish rolling screw thread reinforcing bar specification, and then make concrete test block 1 draw, lower extreme variable cross section steel sheet has restricted the removal of prestressing force finish rolling screw thread reinforcing bar specification first 4 and square anchor plate 3 simultaneously, and then realize the load of holding of concrete test block 1. The continuous load is obtained by the connecting sleeve 6 attached with the strain gauge and also serves as a load sensor, and the fine adjustment of the load is realized by slightly rotating the finish rolling nut specification II 14. In the loading process, the parallelism of the upper and lower variable-section steel plate surfaces is ensured. Then, the test piece is put into an erosion environment simulation device after being loaded, and is placed for a period of time.
Example 2
As shown in fig. 5, a concrete uniaxial tension testing device is provided, a load holding device in an erosion environment simulation device is taken out, and a square steel plate 18 and a penetrating type drawing instrument 19 are newly added on the basis of the load holding device. Two square steel plates 18 are newly added, one of the square steel plates is placed between the upper half connecting sleeve 6 and the rectangular stiffening rib steel plate 10 and used for supporting a through drawing instrument 19 above, the lower part of the square steel plate is fixed by a steel washer 13 and a finish rolling nut specification II 14, and the other square steel plate is arranged above the through drawing instrument 19 and used for supporting the rectangular stiffening rib steel plate 10; the rectangular stiffening rib steel plates 10 are arranged to be supported by square steel plates 18 which are arranged below the rectangular stiffening rib steel plates conveniently; the through type drawing instrument 19 is arranged on the square steel plate 18 and is used for applying tension; as shown in fig. 6, the steel washer 13 and the finish rolling nut gauge two 14 inside the variable cross-section steel plate are removed.
Further, as shown in fig. 7, the square steel plate 18 is provided with five circular preformed holes at four corners and at the center, respectively, and the diameters of the preformed holes at the four corners are larger than the diameters of the two specifications of the prestressed finish-rolled deformed bar 12, and the diameters of the preformed holes at the center are larger than the diameters of the elongated connecting rods 8.
A single-axis tension testing device for concrete is characterized in that an upward force is applied to a square steel plate 18 above the single-axis tension testing device by a through-type drawing instrument 19 during testing, the tensile force is respectively transmitted to a concrete test block 1 through a spherical hinge 11, a lengthened connecting rod 8, a connecting sleeve 6 and a pre-stress finish-rolling screw steel bar specification one 4 at the upper end of the device, meanwhile, the movement of the pre-stress finish-rolling screw steel bar specification one 4 and the square anchor plate 3 is limited by the spherical hinge 11 at the lower end, and further the tensile force is applied to the concrete test block 1 until a test piece is damaged. The tensile force is measured by the connecting sleeve 6 which also serves as a load sensor, and then the tensile strength of the concrete can be calculated by applying a formula.
Finally, the present invention is not limited to the above-described embodiments, but may be variously modified based on the essential content of the present invention, and all modifications which can be directly suggested to a person skilled in the art based on the present disclosure should be regarded as the scope of the present invention.
Claims (6)
1. The single-shaft tension loading and testing device for the concrete is characterized by comprising a concrete test block, a top steel plate, a bottom steel plate, four second prestressed finish rolling screw-thread reinforcing steel bars, two spherical hinges, a common connecting rod, a lengthened connecting rod and two square anchor plates; the top steel plate and the bottom steel plate respectively pass through four second prestressed finish rolling deformed bars and are respectively arranged at the upper part and the lower part of the second prestressed finish rolling deformed bars in parallel; the top steel plate and the bottom steel plate are respectively in rotary contact with the spherical hinge, the lengthened connecting rod is fixedly connected with the spherical hinge positioned at the top into a whole, and the common connecting rod is fixedly connected with the spherical hinge positioned at the bottom into a whole;
the two square anchor plates are fixedly connected with the top end and the bottom end of the concrete test block through four corners of the two square anchor plates respectively, and the middle parts of the two square anchor plates are respectively fixed with first prestressed finish rolling screw-thread steel bars; the end parts of the two first prestressed finish rolling deformed bars are respectively screwed with the connecting sleeves, and the two connecting sleeves are respectively screwed with the common connecting rod and the lengthened connecting rod; the single-shaft tension load holding and testing of the concrete are completed by upwards driving the first prestressed finish rolling twisted steel on the upper part to bear the force;
four finish rolling twisted steel bars are prefabricated at the top end and the bottom end of the concrete test block respectively, and are exposed for a certain length; four corners of the square anchor plate are respectively provided with a preformed hole, four finish rolling threaded reinforcing bars penetrate through the four preformed holes of the corresponding square anchor plate, the finish rolling threaded reinforcing bars are screwed into finish rolling nuts, and the two square anchor plates are connected with a concrete test block into a whole;
four finish rolling nuts are arranged on the bottom steel plate and are screwed with corresponding second prestress finish rolling screw-thread steel bars, and steel washers are arranged between the finish rolling nuts and the bottom steel plate;
the top steel plate and the bottom steel plate are respectively fixed with a reinforced circular steel pipe, and the two reinforced circular steel pipes are respectively sleeved on the lengthened connecting rod and the common connecting rod;
four rectangular stiffening rib steel plates are uniformly arranged in the circumferential direction of the two reinforced round steel pipes and fixedly connected with corresponding steel plates, and are used for connecting the reinforced round steel pipes with the corresponding steel plates in four directions so as to ensure that the spherical hinge is not damaged locally;
the outer surface of the connecting sleeve at the upper part is stuck with a strain gauge which is also used as a load sensor and is connected with a resistance strain gauge through a connecting wire.
2. The concrete uniaxial tension load and test device according to claim 1, wherein the bottom steel plate and the top steel plate are both variable cross-section steel plates.
3. The apparatus according to claim 1, wherein four finishing nuts are provided at the bottom of the top steel plate for screwing with corresponding second prestressed finishing screw bars, and steel washers are provided between the finishing nuts and the top steel plate.
4. The device for testing the uniaxial tension load of the concrete according to claim 1, wherein two middle steel plates are arranged between the upper connecting sleeve and the upper rectangular stiffening rib steel plate, and penetrate through four second prestressed finish rolling screw bars respectively; the middle steel plate is positioned on the upper connecting sleeve, the top of the middle steel plate is used for supporting the through type drawing instrument, the through type drawing instrument is sleeved on the lengthened connecting rod, four finish rolling nuts are arranged at the bottom of the middle steel plate and are screwed with corresponding second prestress finish rolling screw steel bars, and a steel gasket is arranged between each finish rolling nut and each middle steel plate; the other middle steel plate is positioned at the top of the through type drawing instrument.
5. The method for using the uniaxial tensile load testing device for concrete according to claim 3, wherein the uniaxial tensile load testing device for concrete is characterized in that:
by simultaneously rotating four finish rolling nuts at the bottom of the top steel plate, applying an outward force to the top steel plate, sequentially driving the lengthened connecting rod, the connecting sleeve and the first prestressed finish rolling screw-thread steel bar to bear force, and further enabling the concrete test block to be pulled; meanwhile, the bottom steel plate limits the movement of the first prestressed finish rolling threaded steel bar and the square anchor plate, so that the load holding of the concrete test block is realized; the continuous load is obtained by using a connecting sleeve with a strain gauge as a load sensor, and fine adjustment of the load is realized by slightly rotating a finish rolling nut at the bottom of the top steel plate; in the loading process, the parallelism of the upper and lower variable-section steel plate surfaces is ensured.
6. The method for using the uniaxial tensile load and test device for concrete according to claim 4, wherein the uniaxial tensile test for concrete is as follows:
during testing, the through-type drawing instrument applies upward force against the middle steel plate above the through-type drawing instrument, and the tensile force is respectively transmitted to the concrete test block through the spherical hinge at the upper end, the lengthened connecting rod, the connecting sleeve and the first prestressed finish-rolled screw reinforced bar; meanwhile, the spherical hinge at the bottom limits the movement of the first prestressed finish rolling screw-thread steel bar and the square anchor plate, so that the tensile force is applied to the concrete test block until the test piece is damaged; the tensile force is measured by the connecting sleeve which is also used as a load sensor, and then the tensile strength of the concrete can be calculated by applying a formula.
Priority Applications (1)
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| CN112986004B (en) * | 2021-02-09 | 2022-09-09 | 中国科学院金属研究所 | Tension-compression bidirectional high-temperature creep endurance testing machine |
| CN113865990B (en) * | 2021-09-27 | 2024-04-19 | 吉林大学 | Device for simulating drawing test of concrete pile in frozen soil layer |
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