Concrete test piece tensioning device and tensioning method thereof
By designing a tensioning device for concrete specimens, the problem of lack of research on concrete under the coupling state of tensile stress and freeze-thaw in the prior art is solved, and freeze-thawing of concrete specimens under constant tensile stress is achieved. The experiment promoted the study of the frozen resistance of concrete.
Patent Information
- Application Number
- CN202411594721.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-10
- Publication Date
- 2025-02-07
AI Technical Summary
There is a lack of equipment in the prior art that can conduct research on concrete specimens under the state of coupling tensile stress and freeze-thaw, resulting in insufficient research on concrete freeze-thaw under stress.
A concrete specimen tensioning device is designed, and the constant tensile stress application of the concrete specimen through a combined structure of the first cross rod, a vertical rod, a second cross rod, a pressure sensor and a screw rod are realized, and the pressure sensor and Strain gauge monitors and adjusts tension.
The device can accurately apply a predetermined tension force to the concrete specimens to ensure the freeze-thaw test of the specimens under constant tensile stress, which promotes the study of the anti-freeze properties of concrete.
Smart Images
Figure CN119395074A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of concrete specimen tensioning test and relates to a concrete specimen tensioning device and a tensioning method thereof. Background Art
[0002] At present, the research on concrete freeze-thaw theory mainly focuses on the freeze-thaw study of concrete under the effects of freeze-thaw temperature, complex environment, damage and destruction. Most of them are conducted on concrete specimens under stress-free conditions. The reference specification "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" (GBT50082-2009) does not involve freeze-thaw tests of concrete under stress. The freeze-thaw study of stress-free concrete specimens does not require the application of loads, but most concrete in actual projects is under stress. Therefore, it is very necessary to study the freeze-thaw study of concrete under stress.
[0003] In the prior art, there are few studies on the freeze-thaw of concrete components under tensile stress, and tensioning devices that can put concrete specimens in a state of tensile stress and freeze-thaw coupling are even rarer. Therefore, it is necessary to provide a device that can keep concrete specimens under tensile stress at all times, so as to promote the study of the anti-freeze performance of concrete under tensile stress. Summary of the invention
[0004] The purpose of the present invention is to provide a concrete specimen tensioning device and a tensioning method thereof, which can apply constant tensile stress to the concrete specimen and provide conditions for the concrete specimen to perform freeze-thaw tests under the tensile stress.
[0005] The present invention provides a concrete specimen tensioning device, characterized in that it comprises a first cross bar, two vertical bars perpendicular to the first cross bar are welded on the first cross bar, a second cross bar parallel to the first cross bar is set between the upper ends of the two vertical bars, two pressure sensors are arranged on the second cross bar, the bottoms of the two pressure sensors are directly opposite to the upper ends of the two vertical bars, a third cross bar parallel to the second cross bar is set between the tops of the two pressure sensors, three through holes are equidistantly arranged on the first cross bar, the second cross bar and the third cross bar, the through holes on the three cross bars are vertically opposed, a through hole in the middle of each cross bar is located between the two vertical bars, and the other two through holes are respectively located on the outsides of the two vertical bars, three specimen boxes are arranged between the first cross bar and the second cross bar, one of the specimen boxes is located between the two vertical bars, and the other two specimen boxes are respectively located on the outsides of the two vertical bars, a through hole is arranged at the bottom of each specimen box, and each specimen box A concrete specimen is placed inside, a first screw rod is embedded in the lower end of each concrete specimen, and a second screw rod is embedded in the upper end, the first screw rod and the second screw rod respectively extend a certain length outside the two ends of the concrete specimen along the longitudinal direction of the concrete specimen, the lower ends of the three first screw rods respectively pass through the through holes at the bottom of the specimen box and the three through holes on the first cross bar, and are respectively screwed with a first nut at the bottom of the first cross bar, and the gap between the first screw rod and the through hole at the bottom of the specimen box is sealed with AB glue or epoxy resin; the upper ends of the three second screw rods respectively pass through the three through holes on the second cross bar, and are respectively screwed with a second nut on the top surface of the second cross bar, a third screw rod is respectively inserted into the three through holes on the third cross bar, the upper ends of the three third screw rods are respectively screwed with a third nut on the top surface of the third cross bar, and the lower ends of the three third screw rods are respectively connected to the upper ends of the three second screw rods through threaded sleeves.
[0006] The tensioning method of the concrete specimen tensioning device is characterized by comprising the following steps:
[0007] (1) synchronously tightening down three third nuts, the three third nuts applying pressure to the third cross bar, and transmitting the pressure to two pressure sensors, the two pressure sensors are connected to strain gauges, and the readings of the strain gauges are observed until the two pressure sensors are synchronously loaded to a predetermined load, and the predetermined load is set according to the predetermined tensile force applied to the three concrete specimens;
[0008] (2) Tighten the three second nuts downward synchronously. The three second nuts apply pressure to the second crossbar and generate upward tension on the three second screws. The tension is transmitted to the concrete specimen through the second screws. The strain gauge readings are observed until the loads of the two pressure sensors return to zero. At this time, the loads of the pressure sensors are completely transmitted to the concrete specimen, that is, the predetermined tension is applied to the concrete specimen.
[0009] (3) Loosen the threaded sleeve connection between the third screw and the second screw, remove the third cross bar and the three third screws, put the remaining part of the device into a freeze-thaw testing machine, and conduct a freeze-thaw test on the concrete specimen under constant tensile stress.
[0010] The device of the present invention has a simple structure, is convenient for tensioning concrete specimens, can accurately apply a predetermined tensioning force to the concrete specimens, and has a reasonable size design and can be completely placed in a freeze-thaw machine, making it convenient to perform freeze-thaw tests on concrete specimens under tensile stress. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 It is a schematic diagram of the front view structure of the device of the present invention;
[0012] Figure 2 It is a schematic diagram of the side structure of the device of the present invention.
[0013] The reference numerals in the figure are: 1, first horizontal bar; 2, vertical bar; 3, second horizontal bar; 4, third horizontal bar; 5, pressure sensor; 6, specimen box; 7-concrete specimen; 8, first screw rod; 9, second screw rod; 10, third screw rod; 11, first nut; 12, second nut; 13, third nut; 14, threaded sleeve. DETAILED DESCRIPTION
[0014] like Figure 1 , Figure 2As shown, the concrete specimen tensioning device provided by the present invention comprises a first cross bar 1, on which two vertical bars 2 perpendicular to the first cross bar are welded, a second cross bar 3 parallel to the first cross bar is arranged between the upper ends of the two vertical bars 2, two pressure sensors 5 are arranged on the second cross bar 3, the bottoms of the two pressure sensors 5 are directly opposite to the upper ends of the two vertical bars 2, a third cross bar 4 parallel to the second cross bar is arranged between the tops of the two pressure sensors 5, three through holes are equidistantly arranged on the first cross bar 1, the second cross bar 3 and the third cross bar 4, the through holes on the three cross bars are vertically opposite, a through hole in the middle of each cross bar is located between the two vertical bars, and the other two through holes are respectively located on the outsides of the two vertical bars, three specimen boxes 6 are arranged between the first cross bar 1 and the second cross bar 3, one of the specimen boxes 6 is located between the two vertical bars 2, and the other two specimen boxes 6 are respectively located on the outsides of the two vertical bars 2, each specimen box is provided with a through hole at the bottom, and a concrete specimen 7 is placed in each specimen box 6, A first screw rod 8 is embedded in the lower end of each concrete specimen, and a second screw rod 9 is embedded in the upper end. The first screw rod 8 and the second screw rod 9 extend a certain length outside the two ends of the concrete specimen along the longitudinal direction of the concrete specimen 7, respectively. The lower ends of the three first screw rods 8 pass through the through holes at the bottom of the specimen box and the three through holes on the first cross bar, respectively, and are screwed with a first nut 11 at the bottom of the first cross bar 1, and the gap between the first screw rod and the through hole at the bottom of the specimen box is sealed with AB glue or epoxy resin to prevent moisture in the specimen box from flowing out; the upper ends of the three second screw rods 9 pass through the three through holes on the second cross bar 3, respectively, and are screwed with a second nut 12 on the top surface of the second cross bar 3, and a third screw rod 10 is respectively inserted into the three through holes on the third cross bar 4, and the upper ends of the three third screw rods 10 are respectively screwed with a third nut 13 on the top surface of the third cross bar 4, and the lower ends of the three third screw rods 10 are respectively connected to the upper ends of the three second screw rods 9 through threaded sleeves 14.
[0015] When the above-mentioned concrete specimen tensioning device is implemented, the first cross bar, the second cross bar, the third cross bar and the two vertical bars can all be made of 40×40×3mm or 50×50×4mm angle steel; the size of the precast concrete specimen is 100×100×400mm, and the first, second and third screw rods are φ16 threaded rods.
[0016] The tensioning method of the precast concrete specimen tensioning device comprises the following steps:
[0017] (1) Synchronously tightening the three third nuts 13 downward, the three third nuts 13 apply pressure to the third cross bar 4, and transmit the pressure to the two pressure sensors 5, the two pressure sensors are connected to the strain gauge, and the readings of the strain gauge are observed until the two pressure sensors are synchronously loaded to a predetermined load, and the predetermined load is set according to the predetermined tensile force applied to the three concrete specimens;
[0018] (2) Tighten the three second nuts 12 downward synchronously. The three second nuts 12 apply pressure to the second crossbar 3. Since the bottom of the second crossbar is supported by two vertical bars, the lower end of the first screw rod 8 is limited to the bottom of the first crossbar 1 by the first nut 12. Therefore, when the second nut rotates downward, an upward tension force is generated on the three second screw rods 9. The tension force is transmitted to the concrete specimen 7 through the second screw rod 9. The reading of the strain gauge is observed until the load of the two pressure sensors 5 just returns to zero. At this time, the load of the two pressure sensors 5 is completely transmitted to the three precast concrete specimens 7, that is, the predetermined tension force is applied to the three precast concrete specimens 7;
[0019] (3) Loosen the threaded sleeve 14 connecting the third screw rod 11 and the second screw rod 10, remove the third cross bar 5 and the three third screw rods 11, put the remaining part of the device into a freeze-thaw testing machine, and perform a freeze-thaw test on the precast concrete specimen 7 under constant tensile stress.
Claims
1. A concrete specimen tensioning device, characterized in that: The invention comprises a first cross bar, on which two vertical bars perpendicular to the first cross bar are welded, a second cross bar parallel to the first cross bar is set between the upper ends of the two vertical bars, two pressure sensors are arranged on the second cross bar, the bottoms of the two pressure sensors are directly opposite to the upper ends of the two vertical bars, a third cross bar parallel to the second cross bar is set between the tops of the two pressure sensors, three through holes are equidistantly arranged on the first cross bar, the second cross bar and the third cross bar, the through holes on the three cross bars are vertically opposite, a through hole in the middle of each cross bar is located between the two vertical bars, and the other two through holes are respectively located on the outsides of the two vertical bars, three test box boxes are set between the first cross bar and the second cross bar, one of the test boxes is located between the two vertical bars, and the other two test boxes are respectively located on the outsides of the two vertical bars, a through hole is arranged at the bottom of each test box, a concrete test piece is placed in each test box, and each A first screw rod is embedded in the lower end of the concrete specimen, and a second screw rod is embedded in the upper end. The first screw rod and the second screw rod respectively extend a certain length outside the two ends of the concrete specimen along the longitudinal direction of the concrete specimen. The lower ends of the three first screw rods respectively pass through the through holes at the bottom of the specimen box and the three through holes on the first cross bar, and are respectively screwed with a first nut at the bottom of the first cross bar, and the gap between the first screw rod and the through hole at the bottom of the specimen box is sealed with AB glue or epoxy resin; the upper ends of the three second screw rods respectively pass through the three through holes on the second cross bar, and are respectively screwed with a second nut on the top surface of the second cross bar, a third screw rod is respectively inserted into the three through holes on the third cross bar, the upper ends of the three third screw rods are respectively screwed with a third nut on the top surface of the third cross bar, and the lower ends of the three third screw rods are respectively connected to the upper ends of the three second screw rods through threaded sleeves.
2. A tensioning method for the concrete specimen tensioning device according to claim 1, characterized in that: The following steps are involved: (1) synchronously tightening down three third nuts, the three third nuts applying pressure to the third cross bar, and transmitting the pressure to two pressure sensors, the two pressure sensors are connected to strain gauges, and the readings of the strain gauges are observed until the two pressure sensors are synchronously loaded to a predetermined load, and the predetermined load is set according to the predetermined tensile force applied to the three concrete specimens; (2) Tighten the three second nuts downward synchronously. The three second nuts apply pressure to the second crossbar and generate upward tension on the three second screws. The tension is transmitted to the concrete specimen through the second screws. The strain gauge readings are observed until the loads of the two pressure sensors return to zero. At this time, the loads of the pressure sensors are completely transmitted to the concrete specimen, that is, the predetermined tension is applied to the concrete specimen. (3) Loosen the threaded sleeve connection between the third screw and the second screw, remove the third cross bar and the three third screws, put the remaining part of the device into a freeze-thaw testing machine, and conduct a freeze-thaw test on the concrete specimen under constant tensile stress.