CN108414357B - Device for realizing axial compression of steel pipe confined concrete test piece and working method thereof - Google Patents
Device for realizing axial compression of steel pipe confined concrete test piece and working method thereof Download PDFInfo
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- CN108414357B CN108414357B CN201810424938.4A CN201810424938A CN108414357B CN 108414357 B CN108414357 B CN 108414357B CN 201810424938 A CN201810424938 A CN 201810424938A CN 108414357 B CN108414357 B CN 108414357B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 83
- 239000010959 steel Substances 0.000 title claims abstract description 83
- 238000007906 compression Methods 0.000 title claims abstract description 17
- 230000006835 compression Effects 0.000 title claims abstract description 16
- 238000000034 method Methods 0.000 title claims abstract description 15
- 238000005498 polishing Methods 0.000 claims description 3
- 238000003466 welding Methods 0.000 claims description 2
- 238000012669 compression test Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
Classifications
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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
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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
- G01N2203/0019—Compressive
Abstract
The invention relates to a device for realizing axial compression of a steel pipe restrained concrete test piece, which comprises a steel pipe and core concrete poured in the steel pipe, wherein grooves which are not filled with the core concrete are reserved at two ends of the steel pipe, loading heads are arranged in the grooves at two ends of the steel pipe, one end of each loading head is inserted into the groove to be contacted with the end face of the core concrete, the other end of each loading head is provided with a loading cap, and a plurality of unidirectional strain gauges are circumferentially and equidistantly arranged on the side face of each loading head in a surrounding manner; the invention also relates to a working method of the device for realizing the axial compression of the steel tube confined concrete test piece. The invention can more accurately judge whether the concrete is in an axial pressure state by directly observing the numerical value generated by the comparison strain gauge, effectively and accurately adjust the corresponding position of the test piece according to the strain numerical value, ensure that the core concrete is in an axial pressure state in the loading process, and improve the accuracy and reliability of experimental data.
Description
Technical Field
The invention relates to a device for realizing axial compression of a steel tube confined concrete test piece and a working method thereof.
Technical Field
The steel pipe concrete structure has the characteristics of high bearing capacity, good ductility, good earthquake resistance and the like, and is widely applied in the civil engineering field. The stress state of the concrete filled with steel tube is divided into two types, one is that the core concrete is pressed, the steel tube is longitudinally pressed and transversely pulled, and the other is that the core concrete is pressed, and the steel tube is only transversely pulled. Compared with the steel pipe concrete in the first structural form, the steel pipe restrained concrete structure in the latter form has more reasonable stress, can exert the advantages of two materials, has higher bearing capacity and is concerned. The axial compression test of the steel pipe constraint core concrete column is also developed in a laboratory step by step, geometric centering and physical centering are required before the test piece is formally loaded, the traditional physical centering method is to symmetrically paste strain gauges on the outer side surface of the steel pipe of the test piece, judge the stress state of the section of the test piece by observing the data difference of the strain gauges at the same height, then correspondingly adjust the placing position of the test piece, so that the core concrete bears the axially uniform load. When the measured value of the vertical strain gauge is larger, the corresponding applied load is very large, whether cracks develop in the internal concrete or not cannot be observed, whether the actual loading of the test piece is influenced or not cannot be judged, the roughness of the contact interface between the steel pipe and the concrete is different, and the vertical load transmitted to the measuring point with the same height of the steel pipe is different, so that the difference in vertical deformation of the steel pipe is caused. Therefore, the existing test piece physical centering method for the steel tube core constraint concrete column axial compression test cannot observe the stress and deformation of the internal core concrete in the loading process, the centering adjustment result is unreliable, the obtained test data result has larger deviation from the actual result, and the stress and the damage state of the steel tube core constraint concrete column in the axial compression process are not truly reflected.
Disclosure of Invention
In view of the above, the invention aims to provide a device for realizing axial compression of a steel pipe restrained concrete test piece and a working method thereof, which can more accurately judge whether concrete is in an axial compression state or not and improve the accuracy and reliability of experimental results.
In order to solve the technical problems, the technical scheme of the invention is as follows: including steel pipe and pouring at the inside core concrete of steel pipe, the recess of unfilled core concrete is reserved at the both ends of steel pipe, is provided with the loading head in the recess at steel pipe both ends, and loading head one end inserts recess and core concrete terminal surface contact, and the loading head other end sets up the loading cap, is provided with a plurality of unidirectional strain gages along equidistant surrounding in circumference on the side of loading head.
Further, the unidirectional strain gauge is attached to the part of the loading head extending out of the groove.
Further, the section size of the loading head is the same as that of the core concrete, and the measuring direction of the strain gauge is consistent with the height direction of the side face of the loading head.
The other technical scheme provided by the invention is as follows: the working method of the device for realizing the axial compression of the steel pipe confined concrete test piece comprises the device for realizing the axial compression of the steel pipe confined concrete test piece;
(1) One end of the steel pipe is plugged by a plug with a certain depth, core concrete is poured into the steel pipe from the other end of the steel pipe, pouring is stopped after the core concrete is a certain distance away from the pouring end, and the steel pipe is maintained to stand vertically;
(2) After curing for a period of time, the core concrete is completely solidified, and a plug plugged at one end of the steel pipe is taken down, so that the middle section of the steel pipe is filled with the core concrete, grooves are reserved at the two ends of the steel pipe, and the end faces at the two ends of a core concrete test piece in the steel pipe are polished;
(3) After polishing, respectively welding one end surfaces of the two loading heads with the two loading caps, uniformly and circularly attaching a plurality of unidirectional strain gages on the side surface of each loading head at intervals, attaching the strain gages to one end close to the loading caps, respectively plugging one ends of the two loading heads, which are not welded with the loading caps, into grooves at two ends of the steel pipe, and enabling the end surfaces of the loading heads to be in contact with the end surfaces of core concrete;
(4) And applying load to the loading cap, wherein the load direction is perpendicular to the end face of the loading cap, and judging whether the section of the core concrete is uniformly stressed in the axial direction or not by observing the strain quantity generated by a plurality of unidirectional strain gauges attached to the side face of the loading head or not, and whether the position of the steel pipe core concrete test piece needs to be adjusted or not. If the strain amounts generated by the unidirectional strain gages are unequal, and the strain amount difference value generated by each unidirectional strain gage exceeds a certain value, the fact that the strain generated by the stress in different directions on the side face of the loading head is different is further indicated, the fact that the loading head is eccentric due to the axial pressure is further indicated, at the moment, the steel pipe core concrete test piece is subjected to non-axial pressure, loading should be stopped at the moment, the reason that the axial pressure is eccentric is found, and if the strain amount value generated by each unidirectional strain gage is equal or the strain amount difference value generated by each unidirectional strain gage is extremely small, the fact that the strain generated by the stress in different directions on the side face of the loading head is the same is further indicated, the fact that the loading head is well centered due to the axial pressure is further indicated, and at the moment, the steel pipe core concrete test piece is subjected to the axial pressure without adjustment.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention can more accurately judge whether the core constraint concrete is in the axial compression stress state or not directly by observing and comparing the values of the symmetrically arranged strain gages, effectively and accurately adjust the corresponding positions of the test pieces according to the strain values, ensure that the core concrete is in the axial compression stress state in the loading process, and improve the accuracy and the reliability of experimental data;
(2) The invention is suitable for the axle pressure and bias test of the steel pipe core constraint concrete column, and particularly has higher reliability of the physical centering adjustment result in the short axle pressure test;
(3) According to the invention, as the end part of the steel pipe does not need to be welded with a short plate, the consumption of steel is reduced, the test piece processing procedure can be simplified, and the test cost is reduced.
The present invention will be further described in detail below with reference to specific embodiments and associated drawings for the purpose of making the objects, technical solutions and advantages of the present invention more apparent.
Drawings
FIG. 1 is a schematic view of the construction of the present invention;
FIG. 2 is a schematic front view of the steel pipe and concrete test piece construction of the present invention;
FIG. 3 is a schematic front view of the loading mechanism of the present invention;
fig. 4 is a schematic top view of the loading mechanism of the present invention.
In the figure: 1-a steel pipe; 2-core concrete; 3-loading head; 4-unidirectional strain gauge; 5-loading the cap; 6-groove.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings.
As shown in fig. 1-4, a device for realizing axial compression of a steel pipe confined concrete test piece comprises a steel pipe 1 and core concrete 2 poured inside the steel pipe, grooves 6 which are not filled with the core concrete 2 are reserved at two ends of the steel pipe 1, loading heads 3 are arranged in the grooves 6 at two ends of the steel pipe 1, one end of each loading head 3 is inserted into each groove 6 to be in contact with the end face of the core concrete 2, loading caps 5 are arranged at the other end of each loading head 3, and a plurality of unidirectional strain gauges 4 are circumferentially and equidistantly arranged on the side face of each loading head in a surrounding mode.
In this embodiment, the unidirectional strain gauge 4 is attached to the loading head 3 at the position extending out of the groove 6.
In this embodiment, the cross-sectional dimension of the loading head 3 is the same as that of the concrete 2, and the measuring direction of the strain gauge 4 is identical to the height direction of the side surface of the loading head 3.
The working method of the device for realizing the axial compression of the steel pipe confined concrete test piece comprises the device for realizing the axial compression of the steel pipe confined concrete test piece;
(1) One end of a steel pipe 1 is plugged by a plug with a certain depth, core concrete 2 is poured into the steel pipe 1 from the other end of the steel pipe 1, pouring is stopped after the core concrete 2 is a certain distance away from the pouring end, and the steel pipe 1 is maintained to stand vertically;
(2) After curing for a period of time, the core concrete 2 is completely solidified, and a plug plugged at one end of the steel pipe 1 is taken down, so that the middle section of the steel pipe 1 is filled with the core concrete 2, grooves 6 are reserved at two ends of the steel pipe 1, and the end faces at two ends of a test piece of the core concrete 2 in the steel pipe 1 are polished;
(3) After polishing, one end face of each loading head 3 is welded with each two loading caps 5, a plurality of unidirectional strain gages 4 are attached to the side face of each loading head 3 in an equidistant surrounding manner, the unidirectional strain gages 4 are attached to one end close to the loading caps 5, one end, which is not welded with the loading caps 5, of each loading head 3 is respectively plugged into grooves 6 at two ends of a steel pipe 1, and the end face of each loading head 3 is in contact with the end face of core concrete 2;
(4) And (3) applying load to the loading cap 5, wherein the load direction is perpendicular to the end face of the loading cap 5, and judging whether the section of the core concrete 2 is subjected to axially uniform pressure or not by observing the strain quantity generated by a plurality of unidirectional strain gages 4 attached to the side face of the loading head 3, and whether the position of a steel pipe core concrete test piece needs to be adjusted or not. If the strain amounts generated by the unidirectional strain gages 4 are not equal, and the strain amount difference value generated by each unidirectional strain gage 4 exceeds a certain value, the fact that the strain generated by the stress in different directions on the side face of the loading head 3 is different is further indicated, the fact that the loading head 3 is eccentric due to the axial pressure is further indicated, at the moment, the steel pipe core concrete test piece is subjected to non-axial pressure, loading should be stopped at the moment, the reason that the axial pressure is eccentric is found out, and if the strain amount value generated by each unidirectional strain gage 4 is equal or the strain amount difference value is extremely small, the fact that the strain generated by the stress in different directions on the side face of the loading head 3 is the same is further indicated, the fact that the loading head 3 is well centered due to the axial pressure is further indicated, and at the moment, the steel pipe core concrete test piece is not required to be adjusted due to the axial pressure.
The above operation procedures and software and hardware configurations are only preferred embodiments of the present invention, and are not limited to the scope of the present invention, and all equivalent changes made by the descriptions and the drawings of the present invention, or direct or indirect application in the related technical field, are equally included in the scope of the present invention.
Claims (1)
1. The working method of the device for realizing the axial compression of the steel tube confined concrete test piece is characterized by comprising the following steps of:
(1) One end of the steel pipe is plugged by a plug with a certain depth, core concrete is poured into the steel pipe from the other end of the steel pipe, pouring is stopped after the core concrete is a certain distance away from the pouring end, and the steel pipe is maintained to stand vertically;
(2) After curing for a period of time, the core concrete is completely solidified, and a plug plugged at one end of the steel pipe is taken down, so that the middle section of the steel pipe is filled with the core concrete, grooves are reserved at the two ends of the steel pipe, and the end faces at the two ends of a core concrete test piece in the steel pipe are polished;
(3) After polishing, respectively welding one end surfaces of the two loading heads with the two loading caps, uniformly and circularly attaching a plurality of unidirectional strain gages on the side surface of each loading head at intervals, attaching the strain gages to one end close to the loading caps, respectively plugging one ends of the two loading heads, which are not welded with the loading caps, into grooves at two ends of the steel pipe, and enabling the end surfaces of the loading heads to be in contact with the end surfaces of core concrete;
(4) Applying load to the loading cap, wherein the load direction is perpendicular to the end face of the loading cap, and judging whether the section of the core concrete is subjected to axially uniform pressure or not by observing the strain quantity generated by a plurality of unidirectional strain gauges attached to the side face of the loading head, and whether the position of a steel pipe core concrete test piece needs to be adjusted or not; if the strain amounts generated by the unidirectional strain gages are unequal, and the values of the strain amount differences generated by the unidirectional strain gages exceed a certain value, the fact that the strain generated by the stress in different directions on the side surface of the loading head is different is further indicated, the fact that the loading head is eccentric due to the axial pressure is further indicated, at the moment, the steel pipe core concrete test piece is subjected to non-axial pressure, loading should be stopped at the moment, the reason that the axial pressure is eccentric is found out, and if the values of the strain amounts generated by the unidirectional strain gages are equal or the values of the strain amount differences are extremely small, the fact that the strain generated by the stress in different directions on the side surface of the loading head is the same is further indicated, the fact that the loading head is well centered due to the axial pressure is further indicated, and at the moment, the steel pipe core concrete test piece is subjected to the axial pressure without adjustment;
the device for realizing axial compression of the steel pipe confined concrete test piece comprises a steel pipe and core concrete poured inside the steel pipe, grooves which are not filled with the core concrete are reserved at two ends of the steel pipe, loading heads are arranged in the grooves at two ends of the steel pipe, one end of each loading head is inserted into each groove to be in contact with the end face of the core concrete, the other end of each loading head is provided with a loading cap, and a plurality of unidirectional strain gauges are circumferentially and equidistantly arranged on the side face of each loading head in a surrounding mode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201810424938.4A CN108414357B (en) | 2018-05-07 | 2018-05-07 | Device for realizing axial compression of steel pipe confined concrete test piece and working method thereof |
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| CN201810424938.4A CN108414357B (en) | 2018-05-07 | 2018-05-07 | Device for realizing axial compression of steel pipe confined concrete test piece and working method thereof |
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| CN108414357A CN108414357A (en) | 2018-08-17 |
| CN108414357B true CN108414357B (en) | 2024-01-16 |
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| CN109283113B (en) * | 2018-10-31 | 2023-12-29 | 中国矿业大学 | Concrete impermeability test device and test method for eliminating horizontal hoop pressure |
| CN110067339A (en) * | 2019-05-30 | 2019-07-30 | 福州大学 | A kind of high strength steel pipe constraint ultra-high performance concrete rod structure and its construction method |
| CN110455867B (en) * | 2019-07-16 | 2022-02-15 | 黑龙江八一农垦大学 | Boundary recognition device and method for core concrete confinement area of square steel tube concrete column |
| CN111721631B (en) * | 2020-05-11 | 2022-04-19 | 莆田学院 | Device and method for testing ultimate bearing capacity of concrete filled steel tube axial compression short column |
| CN112945705A (en) * | 2021-03-18 | 2021-06-11 | 昆明理工大学 | Model experiment confining pressure loading device and construction method thereof |
| CN113607640B (en) * | 2021-07-21 | 2022-06-21 | 清华大学 | Test analysis method and device for macroscopic occlusal force of steel pipe concrete interface |
| CN113848119A (en) * | 2021-09-27 | 2021-12-28 | 长安大学 | Method and device for testing PBL (Poly-p-phenylene benzobisoxazole) connecting piece in rectangular concrete-filled steel tube structure |
| CN114894623A (en) * | 2022-05-26 | 2022-08-12 | 福州大学 | Steel pipe constrained UHPC column axial pressure bearing capacity test device and test method thereof |
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