CN216926425U

CN216926425U - Special test piece system for UHPC hysteresis performance test

Info

Publication number: CN216926425U
Application number: CN202121076568.3U
Authority: CN
Inventors: 夏瑾
Original assignee: Jiangsu Dongnan Structure Disaster Prevention Engineering Co ltd
Current assignee: Jiangsu Dongnan Structure Disaster Prevention Engineering Co ltd
Priority date: 2021-05-19
Filing date: 2021-05-19
Publication date: 2022-07-08
Anticipated expiration: 2031-05-19

Abstract

The utility model relates to the technical field of ultra-high performance concrete testing, in particular to a special test piece system for a UHPC hysteretic performance test. The test piece system comprises a test piece, a pouring head and a connecting sleeve. The test piece has a measuring section on which a displacement detecting sensor is mounted. The two ends of the measuring section are both provided with connecting sections. The pouring head is provided with a connecting cavity connected with the connecting section in a pouring mode. The connecting sleeve is fixedly arranged on the pouring head. The connecting sleeve is provided with a clamping part for clamping the testing machine. The test piece system is convenient for accurately obtaining a load and displacement curve, further improves the success rate of tests, realizes the test of energy consumption and fatigue strength of the ultra-high performance concrete, evaluates the hysteretic performance of the ultra-high performance concrete structural member, and further provides better guidance suggestions for the building earthquake-resistant design.

Description

Special test piece system for UHPC hysteresis performance test

Technical Field

The utility model relates to the technical field of ultra-high performance concrete testing, in particular to a special test piece system for a UHPC hysteretic performance test.

Background

UHPC (Ultra-High Performance Concrete) is a novel Concrete material with ultrahigh mechanical property and ultrahigh durability. The UHPC has a large amount of anisotropically distributed superfine fiber materials inside, and under the combined action of an extremely low water-cement ratio, the hydration product of the UHPC is very compact, the compressive strength can reach 120MPa-200MPa, and the tensile strength can reach 7MPa-15 MPa.

The hysteresis curve of the reinforced concrete is a load and displacement curve and is used for reflecting the deformation characteristic, rigidity degradation and energy consumption of the concrete structure in the repeated stress process. In the prior art, the hysteretic performance of reinforced concrete is simulated by numerical simulation analysis of a reinforced concrete structural member, so that guidance suggestions are provided for seismic design of buildings, and research on the hysteretic performance of UHPC is lacked.

Hysteresis performance is the performance of the hysteresis curve. The hysteresis curve refers to the load deformation curve of the structure under repeated action, and reflects the deformation characteristics, rigidity degradation and energy consumption of the structure in the repeated stress process. Typical shapes of hysteresis curves are generally four types, shuttle, arcuate, reverse S, and Z. For example, the fusiform shows that the hysteresis curve is full in shape, reflects that the whole structure or component has strong plastic deformation capacity, and has good anti-seismic performance and energy consumption capacity. The hysteretic curve of the structural member is obtained through tests, the anti-seismic performance of the structure can be reflected, and guidance suggestions are provided for the anti-seismic design of the building.

Uniaxial tension and compression tests are generally used in the strength test of the ultra-high performance concrete to obtain the relation between stress and strain. For example, the tensile properties of ultra-high performance concrete are tested by uniaxial tensile test to measure the tensile strength and tensile deformation of ultra-high performance concrete. In the uniaxial tension test, a testing machine is utilized to apply tension loads to two ends of a test block respectively, the test block is continuously and uniformly loaded, and deformation of the test block is measured simultaneously until the test block is broken, so that a load and displacement curve is obtained.

The test block is usually a dog bone test piece, but compared with common concrete, UHPC is often used as a thin-wall structure. Therefore, referring to the manufacturing standard of the existing test block of the common concrete, the actual use state of the UHPC is difficult to characterize, and the structure of the existing test block needs to be optimized. And, because the dog bone test piece is because of the reason of restraint mode and self shape in the experimentation, the dog bone test piece appears stress concentration easily in centre gripping position and variable cross section position, and then leads to the fracture surface to be located outside the range finding section to lead to tensile test's failure.

In order to improve the success rate of obtaining a load and displacement curve, the structure of the dog bone test piece is further optimized in the prior art. Wherein, the dog bone test piece comprises range finding section, changeover portion and tip. The distance measuring section is located in the middle of the test piece and used for arranging an extensometer or a strain gauge, and the distance measuring section is a main body part of the test piece. The end portion is the portion of the test piece to which the apparatus is attached at both ends. The transition section is a portion between the ranging section and the end portion. The transition section is in the form of an arc. However, the problem of stress concentration still occurs in the process of clamping and testing the improved test piece, and even the test piece falls off.

Through retrieval, Chinese patent document CN208283177U discloses a high-precision clamp for UHPC test piece uniaxial tensile test. The fixture is provided with a groove which is fitted with the end shape of the UHPC test piece. The inner end of the groove is a clamping section. The outer end part of the groove is a positioning section. One side of the clamp is provided with a back plate at the position of the groove. The end part of the clamp is also provided with a connecting rod used for being connected with a tensile machine. The joint of the connecting rod and the end part of the clamp is provided with a ball head device.

Although the clamp optimizes the clamping structure of the test piece to a certain extent, in the process of implementing the hysteretic performance test, the testing machine repeatedly loads, unloads and reversely loads two ends of the test piece, so that the displacement value of the test piece structure is difficult to accurately obtain, and the hysteretic performance of the test piece is difficult to evaluate.

In summary, how to design a test block in the hysteretic performance testing process of the ultra-high performance concrete is convenient to accurately obtain a load and displacement curve, so as to evaluate the hysteretic performance of the ultra-high performance concrete structural member and further improve the success rate of the test, and the technical problem to be solved by the technical personnel in the field is urgent.

Disclosure of Invention

The utility model aims to provide a test block for testing the hysteretic performance of ultra-high performance concrete, which is convenient for accurately obtaining a load and displacement curve, better tests the energy consumption and fatigue strength of the ultra-high performance concrete, further improves the success rate of the test, realizes the evaluation of the hysteretic performance of an ultra-high performance concrete structural member, and further provides better guidance suggestion for the building earthquake-resistant design.

In order to achieve the purpose, the utility model adopts the following scheme: a special test piece system for UHPC hysteresis performance test is provided, which comprises a test piece, a pouring head and a connecting sleeve;

the test piece is provided with a measuring section loaded with a displacement detection sensor, and two ends of the measuring section are provided with connecting sections;

the two pouring heads are respectively in one-to-one correspondence with the two connecting sections, and the pouring heads are sleeved on the corresponding connecting sections and poured together with the corresponding connecting sections;

the connecting device is characterized in that the connecting device is connected with two pouring heads which are in one-to-one correspondence with the two pouring heads, the connecting sleeve is fixedly connected with the corresponding pouring heads, and the connecting sleeve is provided with a clamping part for clamping the testing machine.

Preferably, a transition section is arranged between the connecting section and the measuring section. So set up, be favorable to reducing the stress concentration between measurement section and the linkage segment, increased the even region of stress on the test piece, guaranteed that the position that the test piece takes place the fracture surface is located the measurement section, improved experimental success rate.

Preferably, the measuring section and the connecting section are both cylindrical, and the axis of the measuring section coincides with the axis of the connecting section. So set up, measure section and linkage segment and all be cylindricly, compare the prismatic dog bone test piece among the prior art, be favorable to avoiding producing stress concentration between the test piece more, in the test process, the test piece has the region that the stress is even more, is favorable to testing the power consumption and the fatigue strength of ultra high performance concrete, and then has promoted experimental success rate.

Preferably, the diameter of the connecting section is larger than the diameter of the measuring section. So set up, be favorable to the crackle to produce at the measurement section of test piece, be convenient for load the displacement sensor on measuring section lateral wall and obtain continuous effectual displacement value, and then be favorable to assessing the hysteresis quality of super high performance concrete test piece better.

Preferably, the pouring head and the connecting sleeve are connected together through threads. So set up, be convenient for on the one hand the adapter sleeve with pour quick installation and the connection of head, be favorable to accelerating experimental process, on the other hand the adapter sleeve with pour the head and adopt threaded connection's connected mode, compare in prior art test machine anchor clamps to the centre gripping of testpieces, at the in-process of repeated forward loading, uninstallation and reverse loading, threaded connection is favorable to reducing the relative displacement between anchor clamps and the testpieces, the validity of the tip centre gripping of testpieces has been promoted, the accuracy of obtaining the tensile or compression displacement value of testpieces has been improved, and then be favorable to assessing the hysteretic performance of ultra high performance concrete testpieces better, further optimize the earthquake-resistant structural design of building.

Preferably, the two connecting sections are symmetrically distributed along the center of the measuring section. So set up, whole testpieces are symmetrical structure, be favorable to making the testpieces atress more even in hysteresis performance is experimental, and then be favorable to forming stable stress zone at the measurement section of testpieces, thereby promote to form the displacement at the measurement section, avoided producing stress concentration at the linkage segment or the changeover portion of testpieces, thereby lead to forming the crackle at linkage segment or changeover portion, further improved the experimental validity that acquires displacement data, promoted experimental success rate.

Preferably, a riveting structure for increasing the solidification force is arranged in the connecting cavity of the pouring head. So set up, increased the area of contact of the testpieces that ultra high performance concrete made and the inner wall of being connected the chamber, and then promoted the testpieces and pour joint strength between the head, further reduced the risk that the testpieces and anchor clamps drop at the experimental in-process of test hysteresis performance.

Preferably, the transition section is a circular arc transition. So set up, be favorable to further reducing the stress concentration between measurement section and the linkage segment, increased the even region of stress on the test piece, guaranteed that the position that the test piece takes place the fracture surface is located the measurement section, further improved experimental success rate.

Preferably, the measuring section has a diameter of 30mm to 50mm, and the connecting section has a diameter of 60mm to 80 mm.

Preferably, the test piece has a length of 400mm to 500mm and the measuring section has a length of 60mm to 100 mm. So set up, size when according with ultra high performance concrete material in-service use more on the one hand more presses close to true service condition, and on the other hand is favorable to the standardization of test piece.

Compared with the prior art, the special test piece system for the UHPC hysteretic performance test has the following prominent substantive characteristics and remarkable progress: the connecting section of the test piece in the special test piece system for the UHPC hysteretic performance test is nested in the connecting cavity of the pouring head, the pouring head is connected with a clamp of the testing machine through a connecting sleeve, clamping of the cylindrical test piece on the testing machine is realized, accurate test data can be obtained, direct clamping of the test piece by the clamp is avoided, the situation that the test piece is broken due to stress concentration at the clamping position is generated, the direct clamping of the clamp is avoided, the pouring head is prevented from being deformed, smooth test is ensured, and the success rate of the test is further improved.

Drawings

FIG. 1 is a schematic perspective view of a test piece system special for UHPC hysteretic performance test in an embodiment of the present invention;

FIG. 2 is an assembled schematic view of FIG. 1;

FIG. 3 is a cross-sectional view of FIG. 1;

fig. 4 is an end side view of the casting head.

Reference numerals: the test piece comprises a test piece 1, a pouring head 2, a connecting sleeve 3, a riveting structure 4, a measuring section 11, a connecting section 12, a transition section 13, a sleeving part 31 and a clamping part 32.

Detailed Description

The following detailed description of embodiments of the utility model refers to the accompanying drawings.

The test piece system special for the UHPC hysteretic performance test, as shown in figures 1-3, is used for more accurately acquiring the load and displacement curve of a test piece in the hysteretic performance test of the ultra-high performance concrete, and realizing the evaluation of the hysteretic performance of the ultra-high performance concrete structural member. The measuring section and the connecting section of the test piece in the test piece system are preferably cylindrical, and compared with a prismatic dog bone test piece in the prior art, the test piece system is more favorable for avoiding stress concentration between the test pieces, and of course, the measuring section and the connecting section can also be square and other shapes. In the test process, the test piece has a larger area with uniform stress, so that the test on the energy consumption and the fatigue strength of the ultra-high performance concrete is facilitated, and the success rate of the test is further improved.

As shown in fig. 1, a special test piece system for a UHPC hysteretic performance test comprises a test piece 1, a pouring head 2 and a connecting sleeve 3. As shown in fig. 2, the test piece 1 has a measuring section 11 on which a displacement sensor is mounted. The two ends of the measuring section 11 are provided with connecting sections 12. A transition section 13 is arranged between the connecting section 12 and the measuring section 11. The measuring section 11 and the connecting section 12 are both cylindrical. The axis of the measuring section 11 coincides with the axis of the connecting section 12.

The diameter of the connecting section 12 is larger than the diameter of the measuring section 11. So set up, be favorable to the crackle to produce at the measurement section of test piece, be convenient for load the displacement sensor on measuring section lateral wall and obtain continuous effectual displacement value, and then be favorable to assessing the hysteresis quality of ultra-high performance concrete test piece better.

Wherein, the diameter of the measuring section 11 can be selected to be 30mm-50 mm. The diameter of the connecting section 12 may be selected to be 60mm-80 mm. The length of the test piece 1 can be selected from 400mm to 500 mm. The length of the measuring section 11 may be selected to be 60mm to 100 mm. By the arrangement, on one hand, the size of the ultrahigh-performance concrete material in actual use is more consistent, and the ultrahigh-performance concrete material is closer to the actual use working condition; on the other hand, the standardization of the test piece 1 is facilitated.

The transition section 13 may be selected as a circular arc transition. So set up, be favorable to reducing the stress concentration between measuring section 11 and the linkage segment 12, increased the even region of stress on the test piece 1, guaranteed that the position that test piece 1 takes place the fracture face is located measuring section 11, further improved experimental success rate.

As shown in fig. 3, the casting head 2 has a connecting cavity in which the connecting segments 12 are nested. The connecting sleeve 3 is fixedly arranged on the pouring head 2. The adapter sleeve 3 has a clamping portion 32 for clamping the tester.

Wherein, one end of the connecting sleeve 3 is provided with a sleeve joint part 31 for accommodating the pouring head 2. The casting head 2 is connected to the socket 31. Therefore, the pouring head 2 is connected with the clamp of the testing machine through the connecting sleeve 3, and clamping of the cylindrical test piece on the testing machine is achieved. The method is favorable for obtaining accurate test data, avoids the direct clamping of the test piece 1 by the clamp, and enables the situation that the test piece 1 is broken due to stress concentration at the clamping position to occur. Meanwhile, the direct clamping of the fixture for the pouring head 2 is avoided, so that the deformation of the pouring head 2 is avoided. The test is ensured to be carried out smoothly, and the success rate of the test is further improved.

The pouring head 2 and the connecting sleeve 3 can be connected in a threaded manner. The outer wall of the pouring head 2 is provided with first threads, and the inner wall of the connecting sleeve 3 is provided with second threads matched with the first threads. Due to the arrangement, on one hand, the connecting sleeve 3 and the pouring head 2 can be conveniently and rapidly installed and connected, and the test process can be accelerated; on the other hand adapter sleeve 3 and pouring head 2 adopt threaded connection's connected mode, compare in prior art the centre gripping of test machine anchor clamps to testpieces 1, at the in-process of repeated forward loading, uninstallation and reverse loading, threaded connection is favorable to reducing the relative displacement between anchor clamps and testpieces 1. The effectiveness of clamping the end part of the test piece 1 is improved, the accuracy of obtaining the tensile or compressive displacement value of the test piece 1 is improved, the hysteresis performance of the ultra-high performance concrete test piece 1 can be better evaluated, and the earthquake-resistant structure design of a building is further optimized.

As shown in fig. 3, a pair of connecting sections 12 are symmetrically distributed along the center of the measuring section 11. So set up, whole testpieces 1 are symmetrical structure, are favorable to making testpieces 1 atress more even in the hysteresis performance is experimental, and then are favorable to forming stable stress region at testpieces 1's measurement section 11 to the promotion forms the displacement at measurement section 11. Stress concentration on the connecting section 12 or the transition section 13 of the test piece 1, which leads to crack formation on the connecting section 12 or the transition section 13, is avoided. The effectiveness of displacement data obtained in the test is further improved, and the success rate of the test is improved.

As shown in fig. 4, a rivet structure 4 for increasing the solidification joint strength between the test piece 1 and the connection cavity is provided in the connection cavity of the casting head 2. So set up, increased the area of contact of the testpieces 1 that ultra high performance concrete made and the inner wall of being connected the chamber, and then promoted testpieces 1 and pour joint strength between the head 2, further reduced the risk that the in-process testpieces 1 and anchor clamps drop at the test hysteretic performance test. The riveting structure 4 can be a strip-shaped or a net-shaped structure. For example, the rivet structure 4 may be selected as a reinforcing column welded on the inner wall of the connecting cavity to increase the contact area between the test piece 1 and the casting head 2. Alternatively, a mesh pattern may be formed on the inner wall of the connecting cavity, and the mesh pattern constitutes the rivet structure 4 to further increase the contact area between the test piece 1 and the casting head 2. Still alternatively, the rivet structure 4 may be a protrusion or burr provided on the inner wall of the connecting cavity.

When the special test piece system for UHPC hysteretic performance test in the embodiment of the utility model is manufactured, firstly, the pouring head is placed in the mould, then the ultra-high performance concrete is poured into the mould, and after curing in a curing room, the pouring head and the test piece are integrally formed. And finally, mounting the connecting sleeve on the pouring head to finish the manufacture.

The outer wall of the measuring section 11 is loaded with a displacement detection sensor. So set up, be convenient for gather the displacement of test piece 1 in the experimentation in real time, be favorable to drawing the load and the displacement curve that the test piece receives, and then measure the hysteretic performance of ultra-high performance muddy earth better.

The displacement detection sensor can be selected as a resistance strain gauge or a laser length measuring instrument. The resistance strain gauge can be adhered to the surface of the measuring section by 502 glue. After the test piece is taken out of the curing room, the surface of the measuring section can be dried by electric blowing as soon as possible, and then the 502 glue is used for adhering the resistance strain gauge. The resistance strain gauges can be regularly arranged on the side wall of the measuring section according to the requirements of the test.

In order to further accelerate the experiment process, the measuring section 11 is connected with a data acquisition system which simultaneously acquires load and displacement. So set up, realized gathering simultaneously the displacement data that test 1 received load and test 1 produced, be favorable to obtaining the hysteresis curve fast.

The present invention is not limited to the specific technical solutions described in the above embodiments, and other embodiments may be made in the present invention in addition to the above embodiments. It will be understood by those skilled in the art that various changes, substitutions of equivalents, and alterations can be made without departing from the spirit and scope of the utility model.

Claims

1. A special test piece system for UHPC hysteretic performance test is characterized by comprising a test piece, a pouring head and a connecting sleeve;

the connecting sleeve is provided with two pouring heads which are in one-to-one correspondence, the connecting sleeve is fixedly connected with the corresponding pouring heads, and the connecting sleeve is provided with a clamping part for clamping the testing machine.

2. The test piece system special for the UHPC hysteretic performance test of claim 1, wherein a transition section is arranged between the connecting section and the measuring section.

3. The test piece system special for the UHPC hysteretic performance test of claim 1, wherein the measuring section and the connecting section are both cylindrical, and the axis of the measuring section is coincident with the axis of the connecting section.

4. The test piece system special for UHPC hysteretic performance test of claim 3, characterized in that the diameter of the connecting section is larger than the diameter of the measuring section.

5. The special test piece system for the UHPC hysteretic performance test of claim 1, wherein the pouring head and the connecting sleeve are connected together through threads.

6. The test piece system special for UHPC hysteretic performance test of claim 1 or 3, characterized in that the two connecting sections are symmetrically distributed along the center of the measuring section.

7. The special test piece system for the UHPC hysteretic performance test as claimed in claim 1, wherein a riveting structure for increasing the solidification force is arranged in the connecting cavity of the pouring head.

8. The special test piece system for the UHPC hysteretic performance test of claim 2, wherein the transition section is a circular arc transition.

9. The test piece system special for the UHPC hysteretic performance test of claim 3, wherein the diameter of the measuring section is 30-50 mm, and the diameter of the connecting section is 60-80 mm.

10. The test piece system special for UHPC hysteresis performance test as claimed in claim 1 or 9, wherein the length of the test piece is 400mm-500mm, and the length of the measuring section is 60mm-100 mm.