CN103940682B - A kind of testing arrangement of concrete shearing Creep Coefficient and method of testing thereof - Google Patents

Abstract

A kind of testing arrangement of concrete shearing Creep Coefficient and method of testing thereof, testing arrangement comprises a long limit for supporting rood beam test specimen, the support that can make the supported end of rood beam test specimen rotate along supporting-line, another of test specimen is provided with loaded carrier on long limit, is placed with and adds load-carrying in loaded carrier; Along place, long limit is furnished with strain transducer to the center crossover location of rood beam test specimen respectively, and strain transducer sends the signal collecting to collection cabinet by wire. Method of testing comprises builds test specimen to become rood beam test specimen, the compressive strain while recording zero load and tensile strain; Install to place again and add the loaded carrier of load-carrying, record tension and compressive strain after loading, the numeric ratio when with zero load, calculates the elastic strain of load age; Obtain the elastic strain of any time by long-term continuous acquisition; Finally calculate shear creep coefficient according to formula. By utilizing rood beam bending oppositely to load, operate handy and safe more.

Description

A kind of testing arrangement of concrete shearing Creep Coefficient and method of testing thereof

Technical field

The testing arrangement and the method for testing thereof that the present invention relates to a kind of concrete coefficient, be specifically related toA kind of testing arrangement of concrete shearing Creep Coefficient and method of testing thereof.

Background technology

Xoncrete structure is in the time of space-load, and in structure, the stress of any point can be by three normal directionStress and three shear stresses represent (FerdinandP.Beer, E.RussellJohnston,JohnT.Dewolf,etc.,MechanicsofMaterials(5thedition)(M),NewYork,McGrawHill, 2009). In the time calculating concrete beam-type structure, mostly ignore to shear and answeredThe impact of power (Li Liankun, structural mechanics (the 5th edition) (M), Beijing: Higher education publishingSociety, 2010), and between last decade, concrete structure is long span concrete beam formula particularlyThe excessive problem of TERM DEFORMATION of structure starts appearance, and 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）（BurgoyneChris,ScantleburyRichard,WhydidPalaubridgeCollapse[J], TheStructuralEngineer, 2006,84 (11), 30-37), large-sized concreteThe impact of the shear stress of structure starts to cause concern. TERM DEFORMATION main with the stressed of structure withThe Creep Characteristics of material is relevant. Aspect the Creep Characteristics research of material, for axially creeping beThe existing certain means of testing of number, pertinent literature (Cao Guohui, local records, the grinding of Creep Loading EquipmentSystem and application. laboratory research and exploration [J], laboratory research and exploration, 2005,24 (10),31-42) test the pressurized Creep Characteristics of creeping by axial pressure; When eliminating, become factor, rightAlso there is certain research in concrete modulus of shearing etc., pertinent literature (Shi Shi Noboru, concreteShearing strength, modulus of shearing and elastic modelling quantity [J], civil engineering journal, 1999,32 (2):47-52) by the method for reversing, concrete modulus of shearing is tested document (FrankJ.Vechchio,MichaelP.Collins,Themodifiedcompression-fieldtheoryforreinforcedconcreteelementssubjectedtoshear[J],ACIJournal,1986,March-April:219-231) by the calculating of concrete slab edge load application to shear stressMethod is 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, provides one to utilize tenWord beam deflection oppositely loads, the test of concrete shearing Creep Coefficient easy to operate and safeDevice and method of testing thereof.

To achieve these goals, testing arrangement of the present invention comprises for supporting rood beam test specimenA long limit, and the support that rotates along supporting-line of the supported end that can make rood beam test specimen, tenOn another long limit of word beam test specimen, install and be placed with the loaded carrier that adds load-carrying;

Along place, long limit is furnished with strain to the center crossover location of described rood beam test specimen respectivelySensor, 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 by rood beam test specimenA long limit be placed on support;

Second step, at the center of rood beam test specimen crossover location, along place, strain is arranged on long limit respectivelySensor, and strain transducer is connected with collection cabinet by wire, obtaining unloaded pressurized shouldBecome ε_c1And unloaded tensile strain ε_t1；

The 3rd step is installed loaded carrier on another long limit of rood beam test specimen, and is loadingOn bracket, place and add load-carrying, gather the strain stress after loading_c2And ε_t2, calculate two groups of sensingsDevice is at the elastic strain ε of 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, a certain momentThe long-term overall strain ε of t_ct、ε_ttThe strain data that equals this moment deducts unloaded data ε_c1And ε_t1，The shear creep of a certain moment tWhat load age was t0 is mixedSolidifying soil is at the shear creep coefficient in t momentWherein γ₀For 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; Initial bulletWhen property strain is large along the long limit configuration reinforcement of rood beam.

Compared with prior art, testing arrangement of the present invention passes through bracket supports rood beam test specimen, a long limit is installed and is placed with the loading holder that adds load-carrying on another long limit of rood beam test specimenFrame, bear tension, and compression is born on the long limit being supported under the effect that adds load-carrying,The center crossover location of rood beam test specimen is the long limit layout strain transducer along place respectively, and strain passesSensor sends the signal collecting to collection cabinet by wire, finally calculates by correspondingFormula can access concrete shear creep coefficient. Apparatus of the present invention are simple in structure, operationConvenient, reduce loading difficulty, there is higher security.

Preferably, support of the present invention, for welding steel or pedestal type structure, has ensured rood beam examinationThe supported end of part can rotate along supporting-line, avoids test result to impact.

Compared with prior art, first method of testing of the present invention passes through rood beam formwork by test specimenBuild and become rood beam test specimen, a long limit of rood beam test specimen is placed in and on support, records zero loadTime compressive strain and tensile strain; On another long limit, loaded carrier is installed again, and in examinationIn the loaded carrier of part below, place and add load-carrying, now tension is born on this length limit, is supportedLong limit bear compression, record tension and compressive strain after loading, when with zero loadNumeric ratio, calculates the elastic strain of load age; By long-term continuous acquisition, and thenObtain the elastic strain of any time; According to formulaCalculateThe shear creep in a certain moment, the concrete that load age is t0 is at the shearing factor in t momentForMethod 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. strainSensor; 6. gather cabinet.

Detailed description of the invention

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 tenA long limit of word beam test specimen 1, can make the supported end of rood beam test specimen 1 rotate along supporting-lineSupport 2, on another long limit of rood beam test specimen 1, install and be placed with the loading that adds load-carrying 4Bracket 3; Along place, long limit is furnished with strain biography to the center crossover location of rood beam test specimen 1 respectivelySensor 5, 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, longer at anotherLoaded carrier is installed on limit, and places and add load-carrying in loaded carrier below test specimen, addingUnder the effect of load-carrying, tension is born on this length limit, and compression is born, rood beam in the long limit being supportedTwo intersect girders bear respectively positive and negative moment of flexure, hold at certain some concrete of intersection regionBe subject to two vertical direction tensions and compression, actual in pure shearing.

Method of testing of the present invention is:

The first step, makes rood beam test specimen 1, and 1 initial strain hour of rood beam test specimen is directly adoptedMake of plain concrete; When initial elasticity strain is large along the long limit configuration reinforcement of rood beam; According toTarget load age t0 is placed in a long limit of rood beam test specimen 1 on support 2, in supportingUnder effect, bear compression;

Second step, at the center of rood beam test specimen 1 crossover location, along place, long limit layout should respectivelyBecome sensor 5, and strain transducer 5 is connected with collection cabinet 6 by wire, obtain skyCarry 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, andIn the loaded carrier 3 of rood beam test specimen 1 below, place and add load-carrying 4, gather the strain after loadingε_c2And ε_t2, calculate the elastic strain ε of two sensors in load age_c0=ε_c2-ε_c1Withε_t0 ⁼ε_t2-ε_t1；

The 4th step, carries out long-term continuous acquisition to the strain data of rood beam test specimen 1, and certain for the momentCarve the long-term overall strain ε of t_ct、ε_ttThe strain data that equals this moment deducts unloaded data ε_c1Withε_t1, the shear creep of a certain moment tLoad age is t0Concrete at the shear creep coefficient in t momentWherein γ₀For initial shear distortion,By ε_c0And ε_t0Utilize above-mentioned formula to calculate.

Claims (4)

1. a testing arrangement for concrete shearing Creep Coefficient, is characterized in that: comprise forA long limit of supporting rood beam test specimen (1), and can make the supporting of rood beam test specimen (1)The support (2) that end rotates along supporting-line, installs on another long limit of rood beam test specimen (1)Be placed with the loaded carrier (3) that adds load-carrying (4);

Along place, long limit is furnished with the center crossover location of described rood beam test specimen (1) respectivelyStrain transducer (5), strain transducer (5) sends by wire the signal collecting toGather cabinet (6).

2. the testing arrangement of concrete shearing Creep Coefficient according to claim 1, its spyLevy and be: 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, make rood beam test specimen (1), according to target load age t0 by rood beamA long limit of test specimen (1) is placed on support (2);

Second step, each along length limit, place respectively at the center crossover location of rood beam test specimen (1)Arrange one group of strain transducer (5), and by two groups of strain transducers (5) by wire with adoptCollection cabinet (6) connects, and 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 add load-carrying (4) upper placement of loaded carrier (3), gather the strain stress after loading_c2And ε_t2，Calculate the elastic strain ε of two groups of strain transducers (5) in load age_c0＝ε_c2-ε_c1Withε_t0＝ε_t2-ε_t1；

The 4th step, carries out long-term continuous acquisition to the strain data of rood beam test specimen (1), certainThe long-term overall strain ε of one 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 tLoad age isThe concrete of t0 is at the shear creep coefficient in t momentWherein γ₀For initial shear distortion,By ε_c0And ε_t0Utilize formula ${\mathrm{\γ}}_0=\frac{\mathrm{\π}}{2}-2\arctan \left(\frac{1-{\mathrm{\ϵ}}_{c0}/2}{1+{\mathrm{\ϵ}}_{t0}/2}\right)$ Calculate.

4. the method for testing of concrete shearing Creep Coefficient according to claim 3, its spyLevy and be: described rood beam test specimen (1) initial elasticity strain hour directly adopts plain coagulationSoil is made; When initial elasticity strain is large along the long limit configuration reinforcement of rood beam.