DIN 51302-2-2000 Materials testing machines - Strain cylinder test method for compression testing machines for concrete《材料试验机 拉伸 加压和弯曲试验机的检验 建筑材料压力试验机的钩检验》.pdf

1、Ref. No. DIN 51302-2 : 2000-12English price group 07 Sales No. 010708.02DEUTSCHE NORM December 200051302-2Continued on pages 2 to 6. No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,

2、has the exclusive right of sale for German Standards (DIN-Normen).Strain cylinder test for verifying compressiontesting machines for testing concreteTranslation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.ICS 19.060Werkstoffprfma

3、schinen Dehnzylinder-Prfverfahren frDruckprfmaschinen fr BetonIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.ForewordThis standard has been prepared by Technical Committee Werk

4、stoffprfmaschinen of the Normenaus-schuss Materialprfung (Materials Testing Standards Committee). Appendix A of DIN EN 12390-4 deals witha strain cylinder*) test to be carried out using compression testing machines, leaving users the option ofusing alternative methods of testing. Because DIN EN 1239

5、0-4 does not describe the strain cylinder testprocedure in sufficient detail, it was decided to deal with the method in a revised edition of DIN 51302-2.AmendmentsThis standard differs from the August 1986 edition in that references have been updated and the standardhas been editorially revised.Prev

6、ious editionDIN 51320-2: 1986-08.All dimensions are in millimetres.1 ScopeThis standard describes the verification of class 1 and class 2 compression testing machines as inDIN EN 12390-4 by means of a strain cylinder test. Regardless of the maximum capacity of the testingmachine, this test is carrie

7、d out at forces between 200 kN and 2000 kN (see subclause 5.1). Compressiontesting machines as in DIN EN 12390-4 manufactured after publication of this standard shall be tested usinga strain cylinder as specified in clause 4.NOTE: The strain cylinder test is used to evaluate test results from differ

8、ent compression testing machines.It is essential that the seating of the upper platen functions correctly, and that there is correct coordina-tion between all parts of the system (e.g. the contact faces of the platens are flat and the upper and lowerplatens are properly aligned).This standard, toget

9、her withDIN EN 12390-4, December2000 edition, supersedesDIN 51302-2, August 1986edition.*) Translators note: Term as used in specialist literature. Referred to in DIN EN 12390-4 as strain gaugedcolumn.Page 2DIN 51302-2 : 2000-122 Normative referencesThis standard incorporates, by dated or undated re

10、ference, provisions from other publications. These norma-tive references are cited at the appropriate places in the text, and the titles of the publications are listed below.For dated references, subsequent amendments to or revisions of any of these publications apply to thisstandard only when incor

11、porated in it by amendment or revision. For undated references, the latest edition ofthe publication (including any amendments) referred to applies.DIN EN 12390-4 Testing hardened concrete Part 4: Compressive strength Specification for testing ma-chines3 Scope of testingIt shall be checked whethera)

12、 the test force is applied centrally when the test piece is installed centrally (see subclause 5.3);b) the seating of the upper platen allows the latter to align itself with the surface of the test piece on makingcontact;c) the seating of the upper platen locks as the load is increased, so that its

13、position is retained in spite ofany eccentric loading (e.g. due to irregularities in the test piece) (see subclause 5.4).4 Measuring systemA strain cylinder with four complete strain gauge bridges shall be used, permitting measurement of the strain(single values and mean) at four points evenly distr

14、ibuted along the circumference.The display may be digital, with a selector switch allowing separate access to each of the bridges (measuringpoints) and enabling separate zeroing for each measuring point and the mean value to be read for all four points.4.1 Material and dimensions of strain cylinderT

15、he strain cylinder shall be made of steel with a yield point of at least 1200 N/mm. It shall have a diameter, d,of (100 t 0,1) mm and a height, h, of (200 t 1) mm. Its contact faces shall be ground. The deviation from flatnessshall be no more than 0,01 mm per 100 mm, the deviation from parallelism o

16、f the two faces shall not exceed0,03 mm per 100 mm and the deviation from squareness of the cylinder in relation to the contact faces shall notexceed 0,1 mm per 100 mm (i.e. 3).Vertical lines at the foot of the cylinder shall be used to indicate the exact position of the measuring points.4.2 Attachi

17、ng the strain gaugesThe strain gauges shall be attached and the measuring points arranged as shown in figure 1.Other arrangements may be used if they produce equivalent results. The effects of ambient temperature canbe largely compensated for by electrical balancing of the bridges.4.3 Checking the e

18、quality of the output signals from the four measuring pointsReliable measurements depend on all four strain gauges being equally sensitive. This shall be checked oncea year using a rotation test, which may, for example, be carried out on a class 1 compression testing machine.In this test, the upper

19、machine platen shall be set parallel to the contact face of the strain cylinder, and four seriesof measurements shall be carried out with the strain cylinder installed centrally (see subclause 5.1).After each series of measurements, the strain cylinder shall be turned by 90 so that, viewed from the

20、operatingside, the measuring point is at the front for series no. I; on the left for series no. II; at the back for series no. III; on the right for series no. IV.At each discrete test force, the readings at the four measuring points shall be recorded and the mean ratio,Rn, shall be calculated as th

21、e criterion for the equality of signal from them (see clause 6). Table 1 gives thelimiting values for Rn.5 Verification5.1 Putting the strain cylinder in place and taking measurementsThe cylinder shall be placed in the compression testing machine, concentric with the machine axis (to within0,2 mm),

22、using the lower platen or a centred auxiliary platen as the datum. It shall be ensured that the cylindermaintains its position under axial loading, using a fixture such as that shown in figure 2.Page 3DIN 51302-2 : 2000-12When testing using eccentric loading, the strain cylinder shall be displaced b

23、y (6 t 0,1) mm from the machineaxis forwards, backwards, to the left and to the right, and locked in each position. The strain cylinder shall bepositioned so that, viewed from the operating side, measuring point no. 1 is at the front. Measurements shallbe carried out at test forces of 200 kN, 400 kN

24、, 800 kN, 1600 kN and 2000 kN. If the capacity of the testingmachine is less than 2000 kN, measurements shall also be carried out at this force.Figure 1: Arrangement of strain gaugesGauge grid length:20 mm to 30 mm80mm to 90mmMeasuring point no. 1Gauge gridlength6 mm to 10 mmMeasuring point no. 2Mea

25、suring point no. 1Measuring point no. 3Measuring point no. 4Page 4DIN 51302-2 : 2000-12Figure 2: Fixture for putting a strain cylinder in place5.2 Safety requirementsDuring all measurements and especially when the strain cylinder is in an eccentric position, care shall be takento ensure that at none

26、 of the measuring points does the reading exceed the nominal value for the strain cylinderat an axial load of 3 000 kN, i.e., measurements shall only be made up to the test force at which this nominalvalue is recorded at one of the measuring points.The strain cylinder shall be clearly marked as foll

27、ows: “Maximum permitted force to be applied centrally:3 000 kN”. A visual check shall be undertaken to ensure that the safety requirements have been fulfilled.If the strain cylinder is overloaded in an eccentric position, there is a risk of the resulting one-sided compressionof the cylinder producin

28、g horizontal forces which exceed the friction forces between the contact faces of thetesting machine and those of the cylinder, causing the latter to be ejected violently from the testing area.5.3 Checking the central application of force and the self-alignment of the upper machineplatenThe strain c

29、ylinder shall be centred in the testing machine. Four series of measurements shall be carried out,for each of which the upper platen shall be tipped by 3 in a different direction and shall align with the surfaceof the strain cylinder before loading.For measurement series no. 1: platen tipped forward

30、;for measurement series no. 2: platen tipped back;for measurement series no. 3: platen tipped to the left;for measurement series no. 4: platen tipped to the right.The mean, Rn, shall be calculated for each test force from the values recorded at the four measuring points andthe greatest difference be

31、tween the values, DRn, shall be calculated (see clause 6).Neither Rn, as a measure of the applied force nor DRnas a criterion for the self-alignment capacity of the upperplaten shall exceed the limiting values given in table 1.Auxiliary markMagnets withon/off switchAuxiliary marksSpacerPage 5DIN 513

32、02-2 : 2000-125.4 Checking the locking action of the seating of the upper platenThe upper machine platen shall be set parallel to the upper contact face of the strain cylinder. Four measurementseries shall be carried out using eccentric loading, shifting the strain cylinder as follows: 6 mm forward

33、for measurement series no. 5; 6 mm back for measurement series no. 6; 6 mm to the left for measurement series no. 7; 6 mm to the right for measurement series no. 8.Calculate the change in Rnfor each mm of displacement, WV,Hor WL,R, for each test force from the values readat each of the four measurin

34、g points (see clause 6).WV,Hand WL,Rare to be taken as the measure of the misalignment of the upper platen under eccentric loading,with their maximum limits being given in table 1.Table 1: Limiting values for strain cylinder and testing machineLimiting values forLimiting values for testing machine f

35、orTest force, in kN strain cylinder forRnRnDRnWV,Hor WL,R200 t 0,02 0,06400800t 0,01t 0,10 0,100,051 6002 0000,046 Evaluation of resultsFigure 1 shows the arrangement of the measuring points.enreading at measuring point n, i.e. n = 1, 2, 3 or 4;e mean value displayed: =44321eeeee+=(1)Rnstrain ratio

36、for measuring point neeeR=nn(2)Rn,1strain ratio for measuring point n of series no. 1R2,3strain ratio for measuring point no. 2 of series no. 3Rnmean ratio for measuring point n from measurement series nos. 1 to 4 or I to IV (as in subclause 4.3), takinginto account signs preceding the measured valu

37、es.44,3,2,1, nnnnnRRRRR+= (3)DRndifference between the greatest and smallest strain ratios for a measuring point for a test force frommeasurement series 1 to 4 (the operational signs preceding the measurement values shall be taken intoaccount.)DRn= Rn,max Rn,min(4)WV,Hchange in the strain ratio per

38、mm of eccentricity of the strain cylinder (to the front or back) frommeasurement series nos. 5 and 624)()(6,26,15,15,2RRRRW+=HV,(5)WL,Rchange in the strain ratio per mm of eccentricity of the strain cylinder (to the left or right) from measure-ment series nos. 7 and 824)()(8,38,47,47,3RRRRW+=RL,(6)P

39、age 6DIN 51302-2 : 2000-12Annex AExplanatory notesResults obtained when testing the compression strength of concrete cubes may be subject to a high level ofscatter, irrespective of whether machines of the same type are used for testing or not. Figure A.1 shows theresults obtained from two testing ma

40、chines, the results for which exhibit the same level of scatter, but wherethe mean is different for each. Ideally, the means would be identical, but this is not feasible and requirementsneed to be modified so that scatter is acceptable provided it is sufficiently low. This standard has adopted,virtu

41、ally unchanged, the method developed by Foote 1 using the results of compressive strength tests ob-tained from a reference machine to assess the technical quality of other machines to be tested.1 Testing machine as in DIN 51223, December 1977 edition2 Testing machine as in DIN 51223-1, December 1981

42、 draft, and DIN 51302-1, March 1985 edition3 Testing machine as in DIN 51223-1, December 1981 draft, DIN 51302-1, March 1985 edition andDIN 51302-2, August 1986 editionFigure A.2: Results of qualitative reproducibility tests presented as normal distributionBibliography1 Foote, P., A proving device f

43、or concrete tube testing machines (obtainable from: British Cement andConcrete Association, Wexham Springs, Slough SL3 6PL, United Kingdom).FrequencyCompressivestrength, bvMachine no. 1 Machine no. 2Figure A.1: Frequency distribution of the compressive strength of an equal number of specimensmade from the same concrete of a specified quality, determined using two different testing machinesFrequency, fCompressive strength, bv