CN103940682A - Test device of concrete shear creep coefficient and test method thereof - Google Patents
Test device of concrete shear creep coefficient and test method thereof Download PDFInfo
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- CN103940682A CN103940682A CN201410178518.4A CN201410178518A CN103940682A CN 103940682 A CN103940682 A CN 103940682A CN 201410178518 A CN201410178518 A CN 201410178518A CN 103940682 A CN103940682 A CN 103940682A
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- rood beam
- beam test
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Abstract
The invention discloses a test device of a concrete shear creep coefficient and a test method thereof. The test device comprises a bracket which is used for supporting a long edge of a cross beam specimen, so that the support end of the cross beam specimen rotates along a support line, wherein a loading bracket is arranged on the other long edge of the specimen; a loading weight is placed on the loading bracket; and a strain transducer is respectively arranged at the intersected position at the center of the cross beam specimen along the long edge, and conveys the collected signal to a collection case through a lead. The test method comprises the following steps: casting the specimen into the cross beam specimen, and measuring compressive strain and tensile strain in idle load; mounting the loading bracket on which the loading weight is placed, and measuring the compressive strain and the tensile strain after loading; computing the elastic strain of the load age by comparing with the numerical value in idle load; obtaining the elastic strain at any moment by long-term continuous collection; finally computing the shear creep coefficient according to the formula. Thus, reverse loading is carried out through the bending of the cross beam; the test device and the test method are simpler, more convenient and safer to operate.
Description
Technical field
The present invention relates to a kind of proving installation and method of testing thereof of concrete coefficient, be specifically related to a kind of proving installation and method of testing thereof of concrete shearing Creep Coefficient.
Background technology
Xoncrete structure is in the time of space-load, in structure, the stress of any point can represent (Ferdinand P.Beer by three normal stresses and three shear stresses, E.Russell Johnston, John T.Dewolf, etc., Mechanics of Materials (5th edition) (M), New York, Mc Graw Hill, 2009).In the time calculating concrete beam-type structure, mostly ignore the impact (Li Liankun of shear stress, structural mechanics (the 5th edition) (M), Beijing: Higher Education Publishing House, 2010), and between last decade, the concrete structure particularly excessive problem of TERM DEFORMATION of long span concrete beam formula structure starts to occur, practical distortion value is often greater than calculated value (Lou Zhuanhong, the large Major Diseases [J] across footpath beam bridge, highway communication science and technology, 2006, 23 (4), 84-87) (Burgoyne Chris, Scantlebury Richard, Why did Palau bridge collapse[J], The Structural Engineer, 2006, 84 (11), 30-37), the impact of the shear stress of large-sized concrete structure starts to cause concern.TERM DEFORMATION is mainly relevant to the Creep Characteristics of the stressed and material of structure.Aspect the Creep Characteristics research of material, for the existing certain means of testing of axial Creep Coefficient, pertinent literature (Cao Guohui, local records, the development of Creep Loading Equipment and application. laboratory study and exploration [J], laboratory study and exploration, 2005,24 (10), 31-42) test the pressurized Creep Characteristics of creeping by axial pressure, when eliminating, become factor, also there is certain research for concrete modulus of shearing etc., pertinent literature (Shi Shi Noboru, concrete shearing strength, modulus of shearing and elastic modulus [J], civil engineering work journal, 1999, 32 (2): 47-52) by the method for reversing, concrete modulus of shearing is tested, document (Frank J.Vechchio, Michael P.Collins, The modified compression-field theory for reinforced concrete elements subjected to shear[J], ACI Journal, 1986, March-April:219-231) by concrete slab edge load application, the computing method of shear stress are studied.Not yet there is at present the test method for concrete shearing Creep Coefficient.
Summary of the invention
The object of the invention is to for above-mentioned defect of the prior art, provide one to utilize rood beam bending oppositely to load, proving installation and the method for testing thereof of concrete shearing Creep Coefficient easy to operate and safe.
To achieve these goals, proving installation of the present invention comprises a long limit for supporting rood beam test specimen, and the support that can make the supported end of rood beam test specimen rotate along supporting-line, on another long limit of rood beam test specimen, install and be placed with the loaded carrier that adds load-carrying;
Along place, long limit is furnished with strain transducer to the center crossover location of described rood beam test specimen respectively, and strain transducer sends the signal collecting to collection cabinet by wire.
Described support is welding steel or pedestal type structure.
Method of testing of the present invention comprises:
The first step, makes rood beam test specimen, according to target load age t0, a long limit of rood beam test specimen is placed on support;
Second step, at the center of rood beam test specimen crossover location, along place, strain transducer is arranged on long limit respectively, and strain transducer is connected with collection cabinet by wire, obtains unloaded compressive strain ε
c1and unloaded tensile strain ε
t1;
The 3rd step is installed loaded carrier on another long limit of rood beam test specimen, and places and add load-carrying in loaded carrier, gathers the strain stress after loading
c2and ε
t2, calculate the elastic strain ε of two sensors in load age
c0=ε
c2-ε
c1and ε
t0=ε
t2-ε
t1;
The 4th step, carries out long-term continuous acquisition to the strain data of rood beam test specimen, the long-term overall strain ε of a certain moment t
ct, ε
ttthe strain data that equals this moment deducts unloaded data ε
c1and ε
t1, the shear creep of a certain moment t
the concrete that load age is t0 is at the shear creep coefficient in t moment
wherein γ
0for initial shear distortion, by ε
c0and ε
t0utilize above-mentioned formula to calculate.
Described rood beam test specimen initial strain hour directly adopts plain concrete to make; When initial elasticity strain is large along the long limit configuration reinforcement of rood beam.
Compared with prior art, proving installation of the present invention is by a long limit of bracket supports rood beam test specimen, on another long limit of rood beam test specimen, install and be placed with the loaded carrier that adds load-carrying, under the effect that adds load-carrying, bear tension, and compressive stress is born on the long limit being supported, at the center of rood beam test specimen crossover location, along place, strain transducer is arranged on long limit respectively, strain transducer sends the signal collecting to collection cabinet by wire, finally can access concrete shear creep coefficient by corresponding computing formula.Apparatus of the present invention are simple in structure, easy to operate, reduced loading difficulty, have higher security.
Preferably, support of the present invention, for welding steel or pedestal type structure, has ensured that the supported end of rood beam test specimen can rotate along supporting-line, avoids test result to impact.
Compared with prior art, first method of testing of the present invention is built test specimen to become rood beam test specimen by rood beam formwork, and a long limit of rood beam test specimen is placed in to compressive strain and the tensile strain while recording zero load on support; On another long limit, loaded carrier is installed again, and place and add load-carrying in loaded carrier below test specimen, now tension is born on this length limit, compressive stress is born on the long limit being supported, record tension and compressive strain after loading, numeric ratio when with zero load, calculates the elastic strain of load age; By long-term continuous acquisition, and then obtain the elastic strain of any time; According to formula
calculate the shear creep in a certain moment, the concrete that load age is t0 at the shearing factor in t moment is
method of testing is clear and definite, simple to operate.
Brief description of the drawings
The structural representation of Fig. 1 apparatus of the present invention;
The intersection region force diagram of Fig. 2 rood beam test specimen;
In accompanying drawing: 1. rood beam test specimen; 2. support; 3. loaded carrier; 4. add load-carrying; 5. strain transducer; 6. gather cabinet.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in further detail.
Referring to Fig. 1, the inventive system comprises welding steel or pedestal type structure for supporting a long limit of rood beam test specimen 1, the support 2 that can make the supported end of rood beam test specimen 1 rotate along supporting-line, installs and is placed with the loaded carrier 3 that adds load-carrying 4 on another long limit of rood beam test specimen 1; Along place, long limit is furnished with strain transducer 5 to the center crossover location of rood beam test specimen 1 respectively, and strain transducer 5 is sent to the signal collecting gather cabinet 6 by wire.
Referring to Fig. 2, bracket supports is passed through on a long limit of rood beam test specimen, on another long limit, loaded carrier is installed again, and place and add load-carrying in loaded carrier below test specimen, under the effect that adds load-carrying, tension is born on this length limit, and compressive stress is born on the long limit being supported, and two intersection girders of rood beam bear respectively positive and negative moment of flexure, certain some concrete in intersection region bears two vertical direction tensions and compressive stress, actual in pure shearing.
Method of testing of the present invention is:
The first step, makes rood beam test specimen 1, and rood beam test specimen 1 initial strain hour directly adopts plain concrete to make; When initial elasticity strain is large along the long limit configuration reinforcement of rood beam; According to target load age t0, a long limit of rood beam test specimen 1 is placed on support 2, under supporting role, bears compressive stress;
Second step, at the center of rood beam test specimen 1 crossover location, along place, strain transducer 5 is arranged on long limit respectively, and strain transducer 5 is connected with collection cabinet 6 by wire, obtains unloaded compressive strain ε
c1and unloaded tensile strain ε
t1;
The 3rd step is installed loaded carrier 3 on another long limit of rood beam test specimen 1, and places and add load-carrying 4 in loaded carrier 3 below rood beam test specimen 1, gathers the strain stress after loading
c2and ε
t2, calculate the elastic strain ε of two sensors in load age
c0=ε
c2-ε
c1and ε
t0 =ε
t2-ε
t1;
The 4th step, carries out long-term continuous acquisition to the strain data of rood beam test specimen 1, the long-term overall strain ε of a certain moment t
ct, ε
ttthe strain data that equals this moment deducts unloaded data ε
c1and ε
t1, the shear creep of a certain moment t
the concrete that load age is t0 is at the shear creep coefficient in t moment
wherein γ
0for initial shear distortion, by ε
c0and ε
t0utilize above-mentioned formula to calculate.
Claims (4)
1. the proving installation of a concrete shearing Creep Coefficient, it is characterized in that: comprise a long limit for supporting rood beam test specimen (1), and the support (2) that can make the supported end of rood beam test specimen (1) rotate along supporting-line, on another long limit of rood beam test specimen (1), install and be placed with the loaded carrier (3) that adds load-carrying (4);
Along place, long limit is furnished with strain transducer (5) to the center crossover location of described rood beam test specimen (1) respectively, and strain transducer (5) is sent to the signal collecting gather cabinet (6) by wire.
2. the proving installation of concrete shearing Creep Coefficient according to claim 1, is characterized in that: described support (2) is welding steel or pedestal type structure.
3. a method of testing for concrete shearing Creep Coefficient, is characterized in that:
The first step, makes rood beam test specimen (1), according to target load age t0, a long limit of rood beam test specimen (1) is placed on support (2);
Second step, at the center crossover location long limit layout strain transducer (5) along place respectively of rood beam test specimen (1), and is connected by wire strain transducer (5) with collection cabinet (6), obtain unloaded compressive strain ε
c1and unloaded tensile strain ε
t1;
The 3rd step is installed loaded carrier (3) on another long limit of rood beam test specimen (1), and adds load-carrying (4) upper placement of loaded carrier (3), gathers the strain stress after loading
c2and ε
t2, calculate the elastic strain ε of two sensors in load age
c0=ε
c2-ε
c1and ε
t0 =ε
t2-ε
t1;
The 4th step, carries out long-term continuous acquisition to the strain data of rood beam test specimen (1), the long-term overall strain ε of a certain moment t
ct, ε
ttthe strain data that equals this moment deducts unloaded data ε
c1and ε
t1, the shear creep of a certain moment t
the concrete that load age is t0 is at the shear creep coefficient in t moment
wherein γ
0for initial shear distortion, by ε
c0and ε
t0utilize above-mentioned formula to calculate.
4. the method for testing of concrete shearing Creep Coefficient according to claim 3, is characterized in that: described rood beam test specimen (1) initial strain hour directly adopts plain concrete to make; When initial elasticity strain is large along the long limit configuration reinforcement of rood beam.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105092393A (en) * | 2015-09-10 | 2015-11-25 | 长安大学 | Torsion test device and method for concrete shear creep |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102010006163A1 (en) * | 2010-01-20 | 2011-07-21 | Technische Universität Dresden, 01069 | Thrust testing device for determining shearing strength of materials, has frame parts connected to frame, and load introduction elements for introduction of test load at pivots that lie diagonally opposite to each other |
| CN102645382A (en) * | 2012-04-01 | 2012-08-22 | 郑州宇通客车股份有限公司 | Test method for measuring shear strength of welding spots and dedicated tester thereof |
| CN203479605U (en) * | 2013-09-06 | 2014-03-12 | 南京理工大学 | Test piece supporting device for type-III fracture testing experiment |
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2014
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102010006163A1 (en) * | 2010-01-20 | 2011-07-21 | Technische Universität Dresden, 01069 | Thrust testing device for determining shearing strength of materials, has frame parts connected to frame, and load introduction elements for introduction of test load at pivots that lie diagonally opposite to each other |
| CN102645382A (en) * | 2012-04-01 | 2012-08-22 | 郑州宇通客车股份有限公司 | Test method for measuring shear strength of welding spots and dedicated tester thereof |
| CN203479605U (en) * | 2013-09-06 | 2014-03-12 | 南京理工大学 | Test piece supporting device for type-III fracture testing experiment |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105092393A (en) * | 2015-09-10 | 2015-11-25 | 长安大学 | Torsion test device and method for concrete shear creep |
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