CN110376049A - A kind of temperature stress testing machine improving strain acquisition system - Google Patents
A kind of temperature stress testing machine improving strain acquisition system Download PDFInfo
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- CN110376049A CN110376049A CN201910653007.6A CN201910653007A CN110376049A CN 110376049 A CN110376049 A CN 110376049A CN 201910653007 A CN201910653007 A CN 201910653007A CN 110376049 A CN110376049 A CN 110376049A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
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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
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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
- G01N3/06—Special adaptations of indicating or recording means
- G01N3/066—Special adaptations of indicating or recording means with electrical indicating or recording means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/38—Concrete; Lime; Mortar; Gypsum; Bricks; Ceramics; Glass
- G01N33/383—Concrete or cement
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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
- G01N2203/0058—Kind of property studied
- G01N2203/006—Crack, flaws, fracture or rupture
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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
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0075—Strain-stress relations or elastic constants
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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
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/022—Environment of the test
- G01N2203/0222—Temperature
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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
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0682—Spatial dimension, e.g. length, area, angle
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Abstract
The present invention designs a kind of concrete temperature stress testing machine: the concrete temperature stress testing machine includes free test specimen strain acquirement part and constraint test specimen strain acquirement part；The free test specimen strain acquirement part directly measures concrete deformation by measuring the relative displacement for the prism bar being embedded in concrete and across movable-component hole；The strain acquirement part of the constraint test specimen can calculate perpendicular prism bar deflection by dibit displacement sensor and obtain true strain under constraint condition.The present invention improves the strain acquirement method of temperature stress testing machine instantly under the premise of guarantee test insulation, the small and demoulding that rubs are convenient, improves the reproducibility and reliability of test；Devise a kind of temperature stress testing machine easy to operate, measurement accuracy is high, freedom is different with constraint test specimen strain acquirement mode.
Description
Technical field
The present invention relates to concrete construction fields, and in particular to a kind of concrete temperature stress testing machine.
Background technique
Due to the variation, chemical reaction and temperature of contained humidity in concrete in concrete coagulation initial stage or hardening process
The phenomenon that volume contraction that the reasons such as variation will appear.
When concrete in a free state, concrete shrinkage not will lead to apparent adverse consequences.But in actual work
Cheng Zhong, concrete structure is restrained by basis, reinforcing bar or adjacent part can be in different restrained conditions, and concrete pulling is caused to be answered
Power, since concrete tensile strength is not high, concrete shrinkage crack is easily generated.The generation of distress in concrete gently then influences structure
Bearing capacity and service life, it is heavy then will lead to catastrophic accident, bring massive losses to national economy, give people's safety
Bring grave danger.Therefore evaluation concrete is significant in the cracking risk of early stage.
Temperature stress testing machine (TSTM) is the important tool for studying concrete early-stage crack resistance, by constraint test specimen, certainly
It is made of four contraction test specimen, temperature control system and computer control system parts.It is freely become by record early concrete
The characteristics such as shape, restrained deformation, temperature change and restraint stress evaluate concrete with parametric synthesis such as Cracking Temperature, crack stress
Cracking resistance and cracking risk.It is one of current evaluation state-of-the-art equipment of concrete cracking risk.
But there is obvious deficiencies for the method for existing TSTM measurement concrete deformation.
On the deformation measurement of constraint test specimen, people most start the variation table for directly measuring relative distance between motor cross-peen
Show the deformation of confined concrete test specimen.But have certain spacing between die trial and concrete, the contraction and expansion of concrete cannot and
When transmitting be die trial movement.Similarly, on the deformation measurement of free shrink test specimen, someone utilizes measurement dog bone coagulation
The shrinkage of the movable end of native die trial being displaced to indicate free test specimen.It is even more have ignored die trial and upper layer lid and
The frictional resistance of lower layer's sliding rail.
Most researchers are embedded in the steel pole of two constant spacings in concrete side, and the connection of steel pole top with
The parallel carbon fiber stock of concrete, another steel pole connect linear variable differential displacement sensor (LVDT).Remembered using LVDT
The displacement for recording carbon fiber bar indicates the deformation of concrete measurement zone.In view of the mobility and thermal requirements of fresh concrete,
The aperture of mold side should not be too big.Therefore, this method is compared with the experience for depending on operator.And steel pole is difficult to ensure level
And it is not contacted with die trial.If the opening contacts of overhanging steel pole and die trial, steel pole will twist, what should be measured is to shrink
Expansion is measured instead.In addition the deformation of concrete complexity is it is also possible that steel pole twists.This explains temperature-fall period very
What more test datas measured is dilatancy instead.
In order to solve this problem, someone is measured horizontally across concrete, and with LVDT in two sides end with two bars
Relative displacement, then with two sides read average value represent concrete measurement district center deformation.This deformation measurement side
Method may bring very big difficulty to dismantling concrete test specimen after test, so that the precision of damage instrument.
There is researcher to devise a kind of large-scale " environmental cabinet ", it contains concrete sample in measurement process and all sets
It is standby.Also entire room is even transformed into " environmental cabinet " by someone, and the deformation of concrete is surveyed also by two sides insertion steel pole
Amount.Since displacement sensor is in " environmental cabinet ", it is difficult to ignore temperature change carrying out some compensation deals to measurement dress
The influence set, this gives the data measured to increase very big uncertainty.Importantly, since environmental cabinet is excessive, concrete
Moisture, which is difficult to ensure, not to be scattered and disappeared, and it is big that the temperature change of concrete also hardly results in timely environmental cabinet compensation, the sensitivity of temperature control
It gives a discount.In addition, high cost also makes this method be difficult to promote.
Also someone tests " true strain " of concrete in the embedded direct Transducers Embedded in Concrete of displacement sensor.This
Kind method is sufficiently expensive, because sensor is used only once, along with deformation of its test is the local deformation of concrete, and
Overall deformation cannot be represented.
It is noted that the free test specimen of Current Temperatures pressure tester and constraint test specimen are acquired using identical deformation
Method.This is unnecessary, because constraint test specimen acquires difficulty since the limitation of loading end increases deformation, and free test specimen is complete
Concrete deformation directly directly can be reflected by the relative displacement at both ends entirely.
Theoretically, as long as guaranteeing that the environment such as the temperature humidity of two test specimens influence and itself pouring quality is identical, accurately
The concrete deformation measured should be identical, and unrelated with measurement method.
In addition to this, TSTM is the comprehensive test of a consideration multifactor impact, while precise measurement deformation
It needs to guarantee the following:
1, concrete needs insulation as closed as possible, guarantees to scatter and disappear without humidity.The control needs of temperature are sensitive as far as possible,
Temperature gradient will not be generated because of the suddenly change of external environment.In addition the Temperature Distribution of concrete needs as uniform as possible.
2, concrete and the friction of external device (ED) are reduced as far as possible and are contacted.In addition, concrete is made to have enough spaces
Expansion and contraction.The uniformity of concrete stress is not upset.
3, to guarantee the convenience of concrete demoulding, the accurate attribute of TSTM testing machine determines necessary when concrete removal
It is simple quiet as far as possible, avoid violent vibration and percussion.
In conclusion needing to improve under the premise of guarantee test insulation, the small and demoulding that rubs are convenient instantly warm
The strain acquirement method for spending pressure tester, improves the reproducibility and reliability of test.
Summary of the invention
The present invention improves temperature stress instantly under the premise of guarantee test insulation, the small and demoulding that rubs are convenient
The strain acquirement method of testing machine, improves the reproducibility and reliability of test；Devise it is a kind of it is easy to operate, measurement accuracy is high,
The freely temperature stress testing machine different with constraint test specimen strain acquirement mode.
A kind of concrete temperature stress testing machine, including free test specimen strain acquirement part and constraint test specimen strain acquirement portion
Point；The free test specimen strain acquirement part is embedded in the prism bar in concrete and passing through movable-component hole by measurement
Relative displacement come directly measure concrete deformation；The strain acquirement part of the constraint test specimen can be counted by dibit displacement sensor
It calculates perpendicular prism bar and deflects and then obtain true strain under constraint condition.
The fixing end component is used to fixed displacement sensor, and remains stationary against mould ends.
The mobile terminal component is lightweight, hard, the good material of insulation effect on material.It is supported in concreting
Firmly film is used to prevent concrete from flowing, and in addition prevents scattering and disappearing for concrete temperature.
The displacement sensor rosette displacement, the rosette surface polish smooth, the rosette
It is fixed on prism bar top, prism bar passes through the hole of mobile terminal without the constraint by mobile terminal.
Bloom is clipped among mobile terminal and fixing end, prevents its movement for withstanding mobile terminal in casting concrete, to
It is removed after concrete initial set.
Institute's displacement sensors select the sensor of LVDT high-precision (measurement accuracy is not less than 1 micron) to carry out displacement survey
Amount.
In die trial each side place one group described in fixing end component and mobile terminal component.The fixing end group
Part uses the good material at low cost of the big durability of stainless steel isodensity, is used to fixed displacement sensor, and abut mould ends
Keep homeostasis motionless.
The bloom helps out, and in casting concrete, bloom is clipped between fixing end component and mobile terminal component,
Fix mobile terminal component.When starting measurement, small rigid block is removed, mobile terminal component can occur with the expansion of concrete at this time
It is mobile, it will not then prevent concrete mobile when concrete shrinkage, ensure that measurement the data obtained is freely becoming for concrete
Shape.
The prism bar is the hard low density material of low temperature expansion rate, such as small engineering plastic is influenced by temperature change
Material.The rosette polished smooth is screwed into the screw hole of prism boom end.The hole that prism passes through mobile terminal component is inserted into again
Mold.To keep prism bar level to fix, upper rigid foam circle is padded in the hole of mobile terminal component, is kept prism horizontal and is not occurred
Sedimentation.The low-density sponge circle that foam circle changes Kong Geng great is removed when concrete initial set, before guaranteeing prism free displacement
Putting prevents temperature to scatter and disappear.Concrete is represented finally by the relative horizontal displacement for the left and right prism for being embedded in inside concrete
Free Transform.Eliminate the influence of concrete torsional deflection.Finally displacement sensor is mounted in fixing end and is compressed in
The rosette of prism boom end guarantees that tension and compression have enough measurement ranges up to intermediate suitable position, by being embedded in concrete
The relative horizontal displacement of the internal digonous mast in left and right represents the Free Transform of concrete.
The die trial lid oversite concrete test specimen and two sides mobile terminal, without covering the components such as displacement sensor.This
The core component of the above-mentioned test concrete deformation of sample is identical as ambient enviroment, is not influenced by concrete temperature variation.
The free test specimen strain acquirement part of the concrete temperature stress testing machine, by fixing end, bloom and mobile terminal
Component is placed on the two sides of die trial against mould ends, and bloom, which is clipped among mobile terminal and fixing end, to be used in casting concrete
Withstanding mobile terminal prevents its movement.The hole of mobile terminal component is passed through after rosette is screwed into the screw hole of prism boom end
It is inserted into mold, keeps horizontal fixed with rigid foam.For casting concrete in die trial, vibrating spear jolt ramming makes it encase prism bar.To
After concrete initial set, removes cushion block and the foam circle on hole prism bar changed to there are the soft sponge rings of macropore, by displacement sensing
Device is mounted in fixing end, and adjustment position is pressed in displacement sensor on the rosette of prism boom end.Finally by pre-buried
The Free Transform of concrete is represented in the relative horizontal displacement of the left and right prism bar of inside concrete.
The constraint test specimen strain acquirement part of concrete temperature stress testing machine of the present invention includes: mold, installing frame
Frame, displacement sensor, prism bar and its rosette component, foam fixing plate, foam heat-insulating board and lightweight sponge block.
Institute's displacement sensors are the displacement for measuring prism bar different height using upper and lower double LVDT, it is contemplated that concrete
Torsional deformation, pass through the real displacement for calculating available concrete centre.
The installation frame is fixed on the girder steel of testing machine two sides.Dibit displacement sensor is installed on installation frame.Frame
Frame is using the material that temperature deformation coefficient is low, intensity is high and stability is high.
The prism bar same material of the prism bar and free test specimen, and be the prism of rectangular cross-sectional.The insertion of prism bar
It is allowed to deform with concrete synchronous in the middle part of to concrete, and is used to fill rosette apart from constant spacing setting screw hole, up and down
Displacement sensor is pressed respectively against the displacement of recording disc on corresponding rosette, reflects the true of the central core of concrete by calculating
Consolidation shape.
The foam fixing plate is that one piece of raised certain altitude is used to fix prism, the foam material for preventing it from tilting and settling
The slab of matter covers the both ends in dog bone die trial respectively, when specific dimensions prism bar upper section is inserted into foam fixing plate, Ke Yibao
The other end of prism is demonstrate,proved in the positive medial position of die trial.
The foam heat-insulating board is one piece there are the foam slabs of big rectangular opening, and the setting of the rectangular opening makes in test process
Foam heat-insulating board does not contact prism bar, does not influence prism bar with concrete and generates displacement.Foam is fixed after concrete initial set
Plate changes foam heat-insulating board into, and the extremely low sponge block of one layer of quality is in addition covered on prism and guarantees the macropore on cystosepiment by sponge
Block covering is reduced in measurement process and is scattered and disappeared by the temperature of hole under the premise of guaranteeing not influencing the displacement of prism bar.
Application of concrete temperature stress testing machine under the conditions of constraining test specimen strain acquirement:
Two blocks of fixed foam plates are covered into the both ends in dog bone die trial respectively, prism bar is inserted perpendicularly into and guarantees its bottom in die trial
Positive medial position.Fixed foam plate is changed into after concrete initial set and stays eurypyloue foam heat-insulating board, in addition on prism bar
It covers one layer of extremely low sponge block of quality and guarantees that the macropore on cystosepiment is covered by sponge block.Two LVDT are mounted on respectively
It frames up on frame, and is compressed in it on rosette on prism bar, upper and lower two contact points are respectively apart from prism bar bottom
L1And L2.After a certain period of time, it is respectively X that the difference for calculating left and right sides LVDT record data, which obtains contact point translation distance up and down,1
And X2, the true strain of concrete center is Xr, then XrIt can be calculated by formula 1.
The mold and lid of the temperature stress testing machine are provided with temperature control device, and the temperature control device passes through setting water
Pipe, and lead to hot water in water pipe to achieve the purpose that temperature control；In the setting of temp.-controlling water inlet pipe, using water inlet pipe and outlet pipe interval
Distribution can make in concrete heating temperature-fall period, and concrete surface heats more evenly.
The bottom that the position of test specimen is placed in the temperature stress testing machine, is equipped with lubricating oil, vinyl from bottom to top
Film, lubricating oil, vinyl film.The advantages of selecting double-layer films, which is preferably to reduce, rubs, and moisture is prevented to scatter and disappear.
The two sides that the position of test specimen is placed in the temperature stress testing machine, are provided with the thin foamed board of brush oil, work as coagulation
When native hydration heat initial stage expands, foamed board can absorb lateral expansion, reduce lateral confinement and then reduce friction.
The measurement method of concrete center real displacement, the measurement side are carried out using concrete temperature stress testing machine
Method the following steps are included:
Step 1: oil and vinyl film are laid in free die trial；
Step 2: by two groups of fixing end components, bloom and mobile terminal component are placed on the two sides of die trial；Rosette is twisted
Into the screw hole of prism boom end；Mold is inserted into the hole that prism passes through mobile terminal component again, to keep prism bar level to fix
And do not settle, upper rigid foam circle is padded in the hole of mobile terminal component；
Step 3: casting concrete is in die trial, and vibrating spear jolt ramming, concrete is not above die trial.Ethylene is covered after floating
Base film simultaneously seals insulation cover at once.Prism bar is adjusted by level meter, fixes its holding level；
Step 4: after concrete initial set, removing cushion block and the foam circle on hole prism bar changed to there are the soft seas of macropore
Silk floss circle, displacement sensor is mounted in fixing end, adjusts the round metal that position makes displacement sensor be compressed in prism boom end
On disk, freely becoming for concrete is represented finally by the relative horizontal displacement for the left and right prism bar for being embedded in inside concrete
Shape；
Step 5: laying oil and vinyl film by the antifriction method in constraint die trial；
Step 6: casting concrete is in die trial, and vibrating spear jolt ramming, concrete is not above die trial.It is covered after covering film
Insulation cover；
Step 7: two blocks of fixed foam plates being covered into the both ends in dog bone die trial respectively, the hole of tightening up a screw of prism bar is just complete
When being inserted into fixed foam plate, guarantee that displacement sensor in the positive medial position of die trial, is installed in the other end of prism bar, it first will installation
Frame is fixed on die trial both ends, and then dibit displacement sensor is mounted on installation frame respectively, and adjustment installation frame position makes
Displacement sensor is compressed in the small rosette on prism bar, and guarantees that tension and compression have measurement model enough to intermediate suitable position
It encloses, frame is fixedly mounted；
Step 8: upper and lower two contact points are respectively L apart from prism bar bottom1And L2, after a certain period of time, calculate the left and right sides
It is respectively X that the difference of LVDT record data, which obtains contact point translation distance up and down,1And X2, constraint test specimen center deformation is Xr, then Xr
It is calculated by formula 1.
The invention has the advantages that:
(1) sensor is placed directly in by free test specimen strain acquirement by the way of die trial inbuilt displacement sensor
Concrete self-shrinkage is measured in die trial, more the directly self-constriction amount of available concrete, during reducing displacement transfer
The error of generation increases measurement accuracy.
(2) for constraining test specimen strain acquirement, using dibit displacement sensor, it is contemplated that the distortion of prism bar rotates, and utilizes
The reading of two sensors can calculate the real displacement at concrete center, improve the reliability of concrete deformation measurement.
(3) demoulding of free test specimen is more convenient, in off-test, can directly using the prism bar of exposure by concrete from
It is removed in mold.
(4) side-friction for considering concrete and die trial absorbs lateral expansion using the thin foamed board of brush oil, reduces horizontal
It rubs to constraining and then reducing.
Detailed description of the invention
Fig. 1 is that the three-view diagram of free test specimen core component includes: the fixed end elevation of (a) side view (b) top view (c)
(d) mobile end elevation.
Fig. 2 is the placement schematic of free test specimen core component during the test.
Fig. 3 is to constrain the axonometric drawing of test specimen core component during the experiment.
Fig. 4 is the schematic diagram for constraining the fixed prism bar of test specimen.
In figure, 1 is fixing end component, and 2 be mobile terminal component, and 3 be the supporting plate for placing displacement sensor, and 4 is for inserting rib
The hole of mast, 5 be the hole for being inserted into displacement sensor, and 6 be bloom, and 7 be displacement sensor (LVDT), and 8 be prism bar, and 9 are
Rosette, 10 be die trial, and 11 be die trial lid, and 12 be installation frame and its foot-supporting frame, and 13 be double LVDT, and 14 be rosette
Component, 15 be prism bar, and 16 be insulation foam plate, and 17 be fixed foam plate.
Specific embodiment
Below in conjunction with specific embodiment, the present invention is further explained.
One, free test specimen strain acquirement, referring to Fig. 1 and Fig. 2, including coaxial and horizontally disposed fixing end component 1, movement
Hold component 2 and supporting plate 3.The hole 4 that prism passes through on the component of two sides mobile terminal is placed in parallel with die trial longitudinal axis.Displacement sensor
It is inserted into the hole 5 on supporting plate 3, is pressed on the rosette 9 on prism.
The measurement of age early stage concrete free shrink is carried out using above-mentioned measuring device and method, comprising the following steps:
1. laying oil and vinyl film by the antifriction method in die trial.
2. bloom 6 and mobile terminal component 2 are placed on the two sides of die trial by two groups of fixing end components 1.Rosette 9 is twisted
Into the screw hole of 8 end of prism bar.Mold is inserted into the hole 4 that prism passes through mobile terminal component again.To keep prism bar 8 horizontal solid
Determine and do not settle, upper rigid foam circle is padded in the hole of mobile terminal component 4.
3. casting concrete is in die trial, vibrating spear jolt ramming, concrete is not above die trial.It is thin that vinyl is covered after floating
Film simultaneously seals insulation cover at once.Prism bar is adjusted by level meter, fixes its holding level.
4. removing cushion block after concrete initial set and the foam circle on 4 hole prism bar of hole being changed to there are the soft sponges of macropore
Circle is reduced in measurement process and is scattered and disappeared by the temperature of hole under the premise of guaranteeing not influencing the displacement of prism bar.LVDT7 is pacified
In fixing end, adjustment position is compressed in LVDT7 on the rosette 9 of prism boom end, and extremely intermediate suitable position is protected
Card tension and compression have enough measurement ranges.Come finally by the relative horizontal displacement for the left and right prism bar 8 for being embedded in inside concrete
Represent the Free Transform of concrete.
Two, test specimen strain acquirement is constrained, referring to Fig. 3 and Fig. 4, including installation frame and its foot-supporting frame 12, double displacement sensings
Device 13 is separately mounted to away from the installation frame 12 at prism bottom end 175mm and 225mm, and is allowed to and the metal on prism bar 15
The compression of 14 phase of disk.
Utilize the measurement of above-mentioned measuring device and method progress concrete under constrained, comprising the following steps:
1. laying oil and vinyl film by the antifriction method in die trial.
2. casting concrete is in die trial, vibrating spear jolt ramming, concrete is not above die trial.Heat preservation is covered after covering film
Lid.
3. being covered the fixed foam plate 17 of two pieces of thickness 50mm upper lobes cylinder height 100mm respectively the two of dog bone die trial
Head, when the hole of tightening up a screw of 250mm prism 15 is just fully inserted into fixed foam plate 17, (hole of tightening up a screw is apart from concrete surface
When 150mm), guarantee the other end of prism bar 15 in the positive medial position of die trial.Fixed foam plate is changed into after concrete initial set
Eurypyloue cystosepiment 16 is stayed, the extremely low sponge block of one layer of quality is in addition covered on prism bar 15 and guarantees the macropore on cystosepiment
It is covered by sponge block, under the premise of guaranteeing that not influencing prism bar 15 is displaced, reduces in measurement process and dissipated by the temperature of hole
It loses.
4. installing sensor: installation frame 12 being fixed on die trial both ends first, is then respectively mounted on double LVDT13
(respectively away from concrete surface 100mm, 150mm) on installation frame 12, adjustment 12 position of installation frame makes LVDT be compressed in prism
Small rosette 14 on bar 15, and guarantee that tension and compression have enough measurement ranges to intermediate suitable position, frame 12 is fixedly mounted.
Test is to obtain the strain of concrete by the displacement of detection prism bar 15.
5. calculating concrete center to be displaced, if the difference for calculating left and right sides LVDT record data obtains contact point up and down and puts down
Moving distance is respectively X1And X2, then practical concrete deformation X can be by formulaIt is calculated.
Claims (11)
1. a kind of concrete temperature stress testing machine, it is characterised in that: the concrete temperature stress testing machine includes freely
Test specimen strain acquirement part and constraint test specimen strain acquirement part；The free test specimen strain acquirement part is embedded in by measurement
Concrete deformation is directly measured in concrete and across the relative displacement of the prism bar of movable-component hole；The constraint examination
The strain acquirement part of part can calculate perpendicular prism bar deflection by dibit displacement sensor and obtain really becoming under constraint condition
Shape.
2. concrete temperature stress testing machine according to claim 1, it is characterised in that: the free test specimen strain acquirement
Part, comprising: fixing end component, die trial, mobile terminal component and die trial lid；
The die trial two sides are fixing end component, bloom and mobile terminal component, and the bloom is clipped among mobile terminal and fixing end；
It is fixedly installed with the supporting plate for placing displacement sensor on the fixing end component, displacement sensor is installed above supporting plate；
A hole is provided on the mobile terminal component, prism bar one end passes through the hole of mobile terminal without the pact by mobile terminal
Beam, the rosette component polished smooth are screwed into the end of the prism bar other end.
3. concrete temperature stress testing machine according to claim 2, it is characterised in that: set in the hole of mobile terminal component
Set fixed device.
4. concrete temperature stress testing machine according to claim 2, it is characterised in that: the die trial lid only covers mixed
Solidifying soil test specimen and two sides mobile terminal.
5. concrete temperature stress testing machine according to claim 2, it is characterised in that: the sensor uses LVDT
High-precision sensor.
6. concrete temperature stress testing machine according to claim 1, which is characterized in that the constraint test specimen strain acquirement
Part includes: installation frame, die trial, measuring part；
The installation frame is fixed on the girder steel of concrete temperature stress testing machine two sides；
The measuring part is arranged on frame, and the measuring part includes the dibit displacement sensor being mounted on frame,
Sensor is connected on prism bar by rosette；
The foam heat-insulating board is one piece there are the foam slabs of big rectangular opening, is fixed after concrete initial set to replace foam
Plate.
7. concrete temperature stress testing machine according to claim 6, it is characterised in that: cover sponge block on prism and guarantee
Macropore on cystosepiment is covered by sponge block.
8. concrete temperature stress testing machine according to claim 1, it is characterised in that: in the temperature stress testing machine
The two sides for placing the position of test specimen are provided with the thin foamed board of brush oil.
9. concrete temperature stress testing machine according to claim 1, it is characterised in that: the die trial of temperature stress testing machine
It is provided with temperature control device with die trial lid, the temperature control device reaches temperature control by leading to hot water in setting water pipe and water pipe
Purpose；In the setting of temp.-controlling water inlet pipe, it is spaced apart using water inlet pipe and outlet pipe.
10. concrete temperature stress testing machine according to claim 1, it is characterised in that: the temperature stress testing machine
The bottom of the middle position for placing test specimen, is equipped with lubricating oil, vinyl film, lubricating oil, vinyl film from bottom to top.
11. a kind of carry out concrete center real displacement using concrete temperature stress testing machine described in claim 1-10
Measurement method, it is characterised in that the measurement method the following steps are included:
Step 1: oil and vinyl film are laid in free die trial；
Step 2: by two groups of fixing end components, bloom and mobile terminal component are placed on the two sides of die trial；Rosette is screwed into rib
The screw hole of mast end；Mold is inserted into the hole that prism passes through mobile terminal component again, for holding prism bar level fixation and not
It settles, upper rigid foam circle is padded in the hole of mobile terminal component；
Step 3: casting concrete is in die trial, and vibrating spear jolt ramming, concrete is not above die trial.It is thin that vinyl is covered after floating
Film simultaneously seals insulation cover at once.Prism bar is adjusted by level meter, fixes its holding level；
Step 4: after concrete initial set, removing cushion block and the foam circle on hole prism bar changed to there are the soft sponges of macropore
Circle, displacement sensor is mounted in fixing end, adjusts the rosette that position makes displacement sensor be compressed in prism boom end
On, the Free Transform of concrete is represented finally by the relative horizontal displacement for the left and right prism bar for being embedded in inside concrete；
Step 5: laying oil and vinyl film by the antifriction method in constraint die trial；
Step 6: casting concrete is in constraint test specimen die trial, and vibrating spear jolt ramming, concrete is not above die trial.After covering film
Cover insulation cover；
Step 7: two blocks of fixed foam plates being covered into the both ends in dog bone die trial respectively, the hole of tightening up a screw of prism bar is just fully inserted into
When fixed foam plate, guarantee that displacement sensor in the positive medial position of die trial, is installed, first by installation frame in the other end of prism bar
Die trial both ends are fixed on, then dibit displacement sensor is mounted on installation frame respectively, adjustment installation frame position makes to be displaced
Sensor is compressed in the small rosette on prism bar, and guarantees that tension and compression have enough measurement ranges to intermediate suitable position, Gu
Determine installation frame；
Step 8: two contact points are respectively L apart from prism bar bottom1And L2, after a certain period of time, calculate left and right sides LVDT record
It is respectively X that the difference of data, which obtains contact point translation distance up and down,1And X2, constraint test piece deformation is Xr, then XrIt is calculated by formula 1
It obtains.
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