CN101477005B - Specimen end clipping reinforcement method during FRP rib stress relaxation characteristics test - Google Patents
Specimen end clipping reinforcement method during FRP rib stress relaxation characteristics test Download PDFInfo
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- CN101477005B CN101477005B CN2009100451058A CN200910045105A CN101477005B CN 101477005 B CN101477005 B CN 101477005B CN 2009100451058 A CN2009100451058 A CN 2009100451058A CN 200910045105 A CN200910045105 A CN 200910045105A CN 101477005 B CN101477005 B CN 101477005B
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Abstract
The invention provides a method for reinforcing and gripping at an end part of a test piece during stress relaxation test of an FRP rib. A gradient transition section is arranged at a reinforcing section at the end part of the test piece, and an external thread arranged at the reinforcing section is matched with a screw thread of a metal splint with an internal thread to eliminate sliding and creeping of a gripping area at the end part during experiment. The method is specifically realized by the following steps: intertwining a section of fiber cloth soaked by resin and being capable of realizing gradient transition at the end part of the test piece, winding the external thread at the glass fabric intertwined section by a thin fiber strand according to a predetermined thread pitch before resin solidification, matching the external thread with the internal thread of the metal splint, and buckling two prefabricated metal splints coated with release agent to the wound screw thread to be fixed. The method solves the problem that sliding, creeping and the like in the gripping area at the end part of the test piece influence the test results when the FRP rib is subjected to stress relaxation test, and the metal splints can be repeatedly utilized.
Description
Technical field
The invention belongs to composite structure and Mechanics Performance Testing field, relate to the method that a kind of test piece end is strengthened grip.
Background technology
Traditional reinforced concrete structure in use crackle or micro-crack can occur, can make steel bar corrosion when the snow-broth that meets with seawater or saliferous (for the snow melting salting forms the saliferous snow-broth) or when containing corrosive gas-liquid, thereby cause the decline of structural-load-carrying capacity or completely lose; When having the electromagnetic field of high frequency around, reinforcing bar can be because idol stream effect produces heat, causes thermal stress and concrete cracking is destroyed; The steel anchor rod that is widely used in Hydraulic and Hydro-Power Engineering, deep foundation, underground structure, stability of slope, mine laneway supporting or the like may have a strong impact on the serviceable life of anchor pole owing to corroding with the chemical constitution interaction on underground water and stratum; Steel anchor rod weight is big in addition, and make, transport and the installation difficulty, and to needing the fragile cutter of mine laneway steel anchor rod of back production.
These shortcomings at reinforcing bar or steel anchor rod existence, for improving the permanance of engineering structure, reduce the life cycle cost of structure, slip-stick artist and scientist have carried out a lot of explorations, for example adopt stainless steel rebar or coating epoxy resin reinforcing bar to replace traditional reinforcing bar or the like, solved some problems to a certain extent, but still failed thoroughly to deal with problems.Because fiber-reinforced polymer (FiberReinforced Polymer, below brief note is for FRP) possess material property designability, specific strength height, corrosion-resistant, non-conductive, not magnetic conduction, be easy to superior function such as cutting, so become an effective way that addresses the above problem more up hill and dale with the muscle material and the anchor pole of its making; But FRP belongs to hard brittle material, and anisotropy, its modulus difference is also bigger during the difference fiber reinforcement, the anchoring property of FRP muscle and anchor pole and concrete, the soil body or rock mass also is different from reinforcing bar and steel anchor rod, apply it to go a series of basic problems and the problem of application to need research in the actual engineering.
The Chang Zuowei presstressed reinforcing steel uses the FRP muscle because its intensity is higher, during the FRP anchor pole is used also be apply prestressed, therefore understand the basic work that its stress relaxation characteristics is an applying FRP muscle (anchor pole), the method for testing of correspondingly setting up its stress relaxation characteristics of the effective test of cover seems very necessary and meaningful.
The clamping of the test piece end of relevant FRP rib stress relaxation characteristics test and reinforcement mode do not have ripe scheme in the document, adopt strand tapered anchorage, be difficult to eliminate the slippage of ground tackle, if attempt is revised by continuous compensation according to the indication of extensometer, certainly will the drawing-in system error, and the compensation destruction in advance that often causes test specimen repeatedly; Adopt splicing type ground tackle, be difficult to eliminate the draw of tackifier, and to the bad adaptability of testing machine; Therefore develop a kind of new, more effective test material preparation method and just seem very necessary.
Summary of the invention
Test piece end is strengthened the method for grip when the object of the present invention is to provide a kind of FRP of test rib stress relaxation characteristics, it has introduced the gradient transition section at test piece end, concentrate to eliminate the obvious stress that exists at clamping end near zone near free section, strengthen section simultaneously and be provided with external thread, cooperate fixing with the anchor clamps that contain internal thread, it is a kind of FRP muscle influences the factors of test result in regional slippage that takes place of the end of test specimen grip and creep etc. when carrying out stress relaxation test effective ways of eliminating or significantly reduce, also can be used as a kind of method of test piece end reinforcement of the FRP of test muscle tensile property, its advantage is that metal splint is reusable.
For reaching above purpose, solution of the present invention is:
A kind of when testing FRP muscle test specimen the end strengthen the method for grip, it is provided with one section gradient transition section by the reinforcement section at test piece end, concentrate with the stress of eliminating this place, and transition section is provided with external thread, its with the threads engaged of the anchor clamps that contain internal thread to eliminate the slippage and the creep in grip zone, end.
Further, it is by twining one section fiber cloth of having flooded the realization gradient transition of resin at test piece end, then lay out an external thread by predetermined pitch at the section that twines fiber cloth with thin rope bundle before resin solidification, the internal thread of external thread and anchor clamps is complementary.
These anchor clamps are metal splint, and two metal splints prefabricated, that scribble release agent fasten on the screw thread that winds out, and locate, lock by the pin and the bolt that have applied release agent.
This fiber cloth be shaped as trapezoidal shape wide at the top and narrow at the bottom, the width on top is that datum length adds transition section length, the width of bottom is got datum length, the length of fiber cloth and width be according to the diameter of test specimen and the length of anchor clamps, the diameter of internal thread, the THICKNESS CALCULATION of two-way fiber cloth, and the external diameter that the length of cloth can guarantee to be wound in behind the test specimen is advisable than the big 2～3mm of diameter of anchor clamps internal thread.
This fiber cloth is glass fibre, carbon fiber, aramid fiber, basalt fiber cloth.
This metal splint adopts aluminium alloy, and internal thread pitch is 4～5mm on it.
Owing to adopted such scheme, the present invention to have following characteristics: the grip method is strengthened in end of the present invention, and the stress relaxation test that it can be applicable to the FRP muscle has solved the problem that regional slippage that takes place of end grip and creep etc. influence test result; It also can be applicable to the Erichsen test of FRP muscle, and used anchor clamps can reuse.
Description of drawings
Fig. 1 strengthens grip mode synoptic diagram for embodiment of the invention test piece end.
Fig. 2 is the cut-open view of A-A profile line among Fig. 1.
Fig. 3 is a fiber cloth shape synoptic diagram.
Synoptic diagram when Fig. 4 carries out relaxation test for the test specimen that adopts the present invention's processing.
Embodiment
The present invention is further illustrated below in conjunction with the accompanying drawing illustrated embodiment.
If directly utilize the strand tapered anchorage grip in the end of test specimen, no matter adopting the winding fiber cloth to strengthen still overlapping one deck soft metal in the end of test specimen in advance strengthens, all can't avoid between intermediate plate and the anchor cup and the relative slippage between the muscle material of intermediate plate and retaining part, thereby make the distortion of test section can't be constant, Ce Shi stress relaxation data can not truly reflect the stress relaxation characteristics of FRP muscle material according to this, and because the anti-extrusion ability of FRP muscle material is relatively poor, also cause squeeze and destroy easily at the grip position, make test failure; The end need long splicing section usually, and the creep of tackifier is bigger if adopt splicing type ground tackle, certainly will be also the displacement of end be incorporated in the test, and the distortion that influences test section is constant, makes test findings become no longer reliable.
A kind of brand-new lax test piece end reinforcement of carrying out and the method for grip have been proposed for this reason, and used the previous patent of invention that proposes of inventor " method of test piece end reinforcing in FRP muscle/anchor rod tensile property test " (application number: partial content 200810201342.4), the gradient transition section is strengthened having adopted in the end, concentrates to avoid the end obvious stress to occur.
The present invention strengthens and the grip method by adopting new end, the end is approximately zero slippage when having realized relaxation test, the influence of creep also has been limited in the coverage of creep of metal fixture block and testing machine system, usually because the metalwork stress level is lower, the influence of its creep can be ignored.So, when carrying out stress relaxation test, the distortion total amount of test section can keep constant after adding to corresponding stress level, and test can be carried out smoothly.In addition owing to adopted transition section simultaneously, avoided since the muscle material strengthen the stress that the sudden change in cross section, position causes in the end concentrated, thereby reinforcement grip of the present invention system also can be applicable to the test of the tensile property of FRP muscle.
The method of end reinforcement and grip is as follows: twining one section fiber cloth 2 of having flooded the gradient transition realized of resin respectively at the two ends of test specimen muscle material 1 (can be glass fibre, carbon fiber, aramid fiber, basalt fiber cloth etc.), before resin solidification, then lay out an external thread 21 by predetermined pitch at the section that twines fiber cloth with thin rope bundle, require this screw thread 21 and the screw thread 31 of the metal splint 3 of band internal thread 31 to be complementary, prefabricated with being about to, two metal splints 3 that have been coated with release agent fasten on the screw thread 21 that winds out, and with getting ready in advance, the pin and the bolt 4 that have applied release agent are equally located two metal splints 3, locking, treat that two ends all dispose and at room temperature can consider further to place baking oven to carry out (80 ℃ of aftertreatments after the curing, 2 hours), the basic end of test specimen 1 processing so far.Metal splint 3 with the removable end of the situation of backsight testing machine, also can and do suitable processing with clamping plate 3 completely knocked downs at two ends, treat that test specimen 1 is fastening with clamping plate 3 by bolt 4 again again during clamping on testing machine, bolt 4 is under the effect of certain pretightning force, the metal splint 3 and the thread segment of compound substance are interlocked.
As Fig. 1-shown in Figure 2, the making step of test specimen is as follows:
At first, select the intact muscle material of same batch of some standby;
The second, cut out the muscle material 1 of respective length with cutting machine according to the test specimen length dimension;
The 3rd, according to the diameter of muscle material 1 and the ultimate load of estimating, the metal splint 3 of Design and Machining one cover band internal thread 31, the preferential aluminium alloy of the material of metal splint 3 (LY12), internal thread diameter is than the big 6～10mm of muscle material diameter, and pitch adopts 4～5mm; Assort corresponding pin and fastening bolt 4, further deoil, cleaning, release agent application be standby;
The 4th, calculate the length and the width of fiber cloth according to the diameter of muscle material 1 and the length of metal splint 3, the diameter of internal thread 31, the thickness of two-way fiber cloth 2 etc., and cut out standby down with scissors.Fiber cloth 2 be shaped as trapezoidal shape wide at the top and narrow at the bottom, the width on top is that datum length adds transition section length (general desirable 3～5cm), the width of bottom is got datum length.The shape of fiber cloth 2 as shown in Figure 3.The external diameter that the length of cloth can guarantee to be wound in behind the muscle material 1 is advisable than the big 2～3mm of diameter of metal splint 3 internal threads.As diameter is the muscle material of 13mm, if the length of metal splint 3 is got 150mm, screw thread is selected T20 * 4 for use, the bolt centre distance of fastening bolt 4 is got 40mm, minor diameter of thread is 16mm, thick about 0.2mm after the two-way fiber cloth individual layer application of resin, the external diameter that expectation is twined after the fiber cloth reaches 19mm, and then the length of required fiber cloth is about π (19
2-13
2)/4/0.2mm, width 150+ (30～50) mm on top, the width 150mm of bottom;
The 5th, the preparation resin is coated with on the fiber cloth 2 of quantity of resin under cutting out, and fiber cloth 2 is wound on the relevant position of muscle material 1, forms the transition section of expectation; And then lay out one section external thread 21 with the moderate fibrous bundle of a branch of thickness by the pitch of metal internal thread 31 on the fiber cloth that has just twined, be the screw thread 21 that obtains suiting, during the winding rope bundle, tension force will be controlled at about 3KG;
The 6th, the metal splint of getting ready 3 is fastened on the external thread 21 that winds out, two metal splints 3 are located, locked by the pin hole 33 on the metal splint 3, bolt hole 32 with same pin and the bolt 4 that has applied release agent, the locking torque of bolt 4 is consistent as far as possible;
The 7th, repeated for the 5th, the 6th step, strengthen an other end of test specimen;
The 8th, treat that it solidifies after, can consider further to place baking oven to carry out aftertreatment (80 ℃, two hours);
The 9th, according to the metal splint 3 of the removable end of the situation of testing machine, also can the clamping plate completely knocked down at two ends is standby;
The tenth, the end face load of the metal splint 3 that clamps by two ends during test, and then effective interlock of the internal thread 31 by metal splint 3 and the compound substance external thread 21 that winds out with Load Transfer to FRP muscle material 1.
Synoptic diagram when Fig. 4 carries out relaxation test for the test specimen that adopts the present invention's processing, its fixing test specimen 1 on test rack 8 carries out the stress relaxation characteristics test by pressure transducer 6 and moving beam 7.
The above-mentioned description to embodiment is can understand and apply the invention for ease of those skilled in the art.The person skilled in the art obviously can easily make various modifications to these embodiment, and needn't pass through performing creative labour being applied in the General Principle of this explanation among other embodiment.Therefore, the invention is not restricted to the embodiment here, those skilled in the art should be within protection scope of the present invention for improvement and modification that the present invention makes according to announcement of the present invention.
Claims (5)
1. a test piece end when testing the FRP rib stress relaxation characteristics is strengthened the method for grip, it is characterized in that: it is provided with one section gradient transition section by the reinforcement section at test piece end, concentrate with the stress of eliminating this place, and strengthen section external thread is set, its with the threads engaged of the anchor clamps that contain internal thread to eliminate the slippage and the creep in grip zone, end, it specifically is by twining one section fiber cloth of having flooded the realization gradient transition of resin at test piece end, then lay out an external thread by predetermined pitch at the section that twines fiber cloth with thin fiber rope bundle before resin solidification, the internal thread of external thread and anchor clamps is complementary.
2. test piece end is strengthened the method for grip during test as claimed in claim 1 FRP rib stress relaxation characteristics, it is characterized in that:
These anchor clamps are metal splint, and two metal splints prefabricated, that scribble release agent fasten on the screw thread that winds out, and locate, lock by the pin and the bolt that have applied release agent.
3. test piece end is strengthened the method for grip during test as claimed in claim 1 FRP rib stress relaxation characteristics, it is characterized in that: this fiber cloth be shaped as trapezoidal shape wide at the top and narrow at the bottom, the width on top is that datum length adds transition section length, the width of bottom is got datum length, the length of fiber cloth and width be according to the diameter of test specimen and the length of anchor clamps, the diameter of internal thread, the THICKNESS CALCULATION of two-way fiber cloth, and the external diameter that the length of cloth can guarantee to be wound in behind the test specimen is advisable than the big 2～3mm of diameter of anchor clamps internal thread.
4. test piece end is strengthened the method for grip during test as claimed in claim 1 FRP rib stress relaxation characteristics, and it is characterized in that: this fiber cloth is glass fibre, carbon fiber, aramid fiber, basalt fiber cloth.
5. test piece end is strengthened the method for grip during test as claimed in claim 2 FRP rib stress relaxation characteristics, it is characterized in that: this metal splint adopts aluminium alloy, and internal thread pitch is 4～5mm on it.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100451058A CN101477005B (en) | 2009-01-09 | 2009-01-09 | Specimen end clipping reinforcement method during FRP rib stress relaxation characteristics test |
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| CN2009100451058A CN101477005B (en) | 2009-01-09 | 2009-01-09 | Specimen end clipping reinforcement method during FRP rib stress relaxation characteristics test |
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| CN101477005A CN101477005A (en) | 2009-07-08 |
| CN101477005B true CN101477005B (en) | 2010-12-01 |
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Families Citing this family (11)
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| CN101858838A (en) * | 2010-06-02 | 2010-10-13 | 沈阳建筑大学 | Intelligent rib end pressurizing mold |
| CN101979991A (en) * | 2010-09-16 | 2011-02-23 | 南京林业大学 | Test specimen for testing tensile property of bamboo or wooden material |
| CN104111197B (en) * | 2014-08-06 | 2016-06-01 | 东北石油大学 | A kind of joint coal petrography direct tensile test device and test method |
| CN105716949B (en) * | 2016-04-13 | 2018-07-03 | 桂林理工大学 | A kind of test method for testing FRP cloth stress relaxation |
| CN105699190B (en) * | 2016-04-13 | 2018-07-03 | 桂林理工大学 | A kind of experimental rig for testing FRP cloth stress relaxation |
| CN106568646A (en) * | 2016-10-19 | 2017-04-19 | 江苏大学 | FRP reinforcement tension test apparatus and test method |
| CN106568650B (en) * | 2016-11-09 | 2019-01-18 | 江苏法尔胜研发中心有限公司 | A kind of carbon fiber composite reinforcement stress relaxation ability test method |
| CN112881163B (en) * | 2021-01-26 | 2022-09-20 | 郑州大学 | FRP (fiber reinforced plastic) rod end anchoring and fixing device with telescopic butterfly-shaped clamp and method |
| CN113073790B (en) * | 2021-04-07 | 2022-12-09 | 浙江大学 | Mechanical anchoring method for FRP (fiber reinforced Plastic) section bar in FRP reinforced concrete composite structure |
| CN113640120B (en) * | 2021-09-07 | 2024-04-05 | 郑州大学 | Device and method for testing tensile mechanical properties of high polymer grouting material |
| CN118531955A (en) * | 2024-06-05 | 2024-08-23 | 重庆交通大学 | Simple FRP rib anchoring device and processing method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101235663A (en) * | 2008-03-11 | 2008-08-06 | 东南大学 | Clip type anchorage applying to carbon fiber reinforced polymeric material prestressing force rib |
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- 2009-01-09 CN CN2009100451058A patent/CN101477005B/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101235663A (en) * | 2008-03-11 | 2008-08-06 | 东南大学 | Clip type anchorage applying to carbon fiber reinforced polymeric material prestressing force rib |
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