1、Designation: C 1196 09Standard Test Method forIn Situ Compressive Stress Within Solid Unit MasonryEstimated Using Flatjack Measurements1This standard is issued under the fixed designation C 1196; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of theaverage compressive stress in existing unrei
3、nforced solid-unitmasonry (see Note 1). This test method concerns the measure-ment of in-situ compressive stress in existing masonry by useof thin, bladder-like flatjack devices that are installed in sawcut mortar joints in the masonry wall. This test methodprovides a relatively non-destructive mean
4、s of determiningmasonry properties in place.NOTE 1Solid-unit masonry is that built with stone, concrete, or clayunits whose net area is equal to or greater than 75 % of the gross area.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathema
5、ticalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and healt
6、h practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E74 Practice of Calibration of Force-Measuring Instru-ments for Verifying the Force Indication of Testing Ma-chines3. Summary of Test Method3.1 When a slot is formed in the
7、masonry, compressivestress at that point will cause the masonry above and below theslot to move together. Compressive stress in the masonry maybe measured by inserting a flatjack into the slot and increasingits internal pressure until the original distance between pointsabove and below the slot is r
8、estored. The state of compressivestress in the masonry is approximately equal to the flatjackpressure multiplied by factors which account for the physicalcharacteristics of the jack and the ratio of (a) the bearing areaof the jack in contact with the masonry to (b) the bearing areaof the slot.4. Sig
9、nificance and Use4.1 Stress is applied as pressure over the area of the flatjack.In the case of multi-wythe masonry, stress is estimated only inthe wythe in which the flatjack is inserted. Stress in otherwythes may be different.5. Apparatus5.1 Flatjack:5.1.1 Aflatjack is a thin envelope-like bladder
10、 with inlet andoutlet ports which may be pressurized with hydraulic oil.Flatjacks may be of any shape in plan, and are designed to becompatible with the masonry being tested. Typical configura-tions are shown in Fig. 1.5.1.2 For determination of the state of compressive stress,dimension A should be
11、equal to or greater than the length of asingle masonry unit, but not less than 8 in. (200 mm).Dimension B should be equal to or greater than the thicknessof one wythe and not less than 3 in. (75 mm). The radius, R, forcircular and semi-rectangular flatjacks shall be equal to theradius of the circula
12、r saw blade used to cut the slot.5.1.3 Flatjacks shall be made of metal or other material suchthat the flatjack in a slot in masonry will be capable of applyingoperating pressures up to the expected maximum flatjackpressure. See Note 2. Metal flatjacks suitable for this purposeshall be made of type
13、304 stainless steel sheet of 0.024 in. (0.6mm) to 0.048 in. (1.2 mm) in thickness with welded seamsalong the edges and incorporating hydraulic inlet or outletports.NOTE 2A maximum operating pressure of 1000 psi (6.9 MPa) or lessis often adequate for older existing masonry, but flatjacks with highero
14、perating pressures may be required for more recently constructedbuildings. Flatjacks manufactured with flexible polymers that have oper-ating pressure ranges of less than 1000 psi (6.9 MPa) may be useful forstress measurements in some historic masonry.1This test method is under the jurisdiction of A
15、STM Committee C15 onManufactured Masonry Units and is the direct responsibility of SubcommitteeC15.04 on Research.Current edition approved June 1, 2009. Published July 2009. Originally approvedin 1992. Last previous edition approved in 2004 as C 1196 04.2For referenced ASTM standards, visit the ASTM
16、 website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr H
17、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.1.4 Calibrate all flatjacks as described in Section 7 todetermine their pressure-applied load characteristics.5.2 Hydraulic SystemA hydraulic pump with hydraulichoses is required. Hose connections shall fit the flatjack inle
18、tport. Measure pressure using gages calibrated to a traceablestandard having both an accuracy of 1 % of full hydraulic scaleand an appropriate operating range. The hydraulic system shallbe capable of maintaining constant pressure within 1 % of fullscale for at least 5 min.5.3 Displacement Measuremen
19、tMeasure displacementsof the masonry by a mechanical gage extensometer whichmeasures the distance between fixed gage points on themasonry as shown in Fig. 2. The method or device used tomeasure deformations shall be capable of deformation mea-surements up to316 in. (5 mm). Deformation measurementssh
20、all have an accuracy of at least 60.005 % of gage length.5.4 Gage PointsUse adhered metal discs or embeddedmetal inserts as gage points during the measurement process.Attach gage points securely to the masonry (using a rigidadhesive for discs or cementitious grout for plugs) which willprevent moveme
21、nt and ensure the required measurement accu-racy. The gage points shall have a conical depression at theircenter, compatible with the pointed elements of the extensom-eter. The angles of the depression of the cone and theextensometer points shall be the same.6. Preparation of Slots6.1 Slots in mason
22、ry are normally prepared by removing themortar from masonry bed joints to avoid disfiguring themasonry. Remove all mortar in the bed joint, so that pressureexerted by a flatjack shall be directly against the surfaces of themasonry units.6.2 The plan geometry of the slot shall be similar to that ofth
23、e flatjack being used. Plan dimensions of the prepared slotshall not exceed those of the flatjack by more than12 in. (12mm).6.3 Slots:6.3.1 Rectangular slots into which rectangular flatjacks areto be inserted may be formed by drilling adjacent or overlap-ping holes (stitch drilling) and subsequently
24、 using a drill, bar,or tool to remove mortar and produce a slot of desireddimensions with smooth upper and lower surfaces.6.3.2 Cut slots for circular and semi-rectangular flatjacksusing circular saws of sufficient radius to provide the depthrequired (Fig. 1, dimension B). Use carbide or diamond tip
25、pedblades to remove all mortar from the slot.7. Calibration7.1 A flatjack has an inherent stiffness which resists expan-sion when the jack is pressurized. Therefore, the fluid pressurein the flatjack is greater than the stress the flatjack applies tomasonry. A flatjack must be calibrated to provide
26、a conversionfactor, Km, to relate internal fluid pressure to stress applied.7.2 Calibrate flatjacks in a compression machine of at least100 kip (450 KN) capacity which has been calibrated accord-ing to Practice E74.7.3 Place a 2 in. (50 mm) thick steel bearing plate on thelower platen of the compres
27、sion machine. The bearing plateshall be of sufficient size to completely cover the flatjack beingcalibrated. Place the flatjack on the lower bearing plate suchthat the edge of the flatjack with the inlet/outlet ports iscoincident with the edge of the bearing plate. Place steelspacers around the othe
28、r edges of the flatjack. The thickness ofthe spacers shall be equal to approximately 113 times thecombined thickness of the two sheets used in fabrication. Placethe upper 2 in. (50 mm) thick bearing plate on top of the shimsand flatjack, and align it to be directly above the lower bearingplate. Posi
29、tion the bearing plate/flatjack/shim assembly on thelower platen such that the centroid of the area of the flatjack iswithin14 in. (6 mm) of the axis of thrust of the test machine.The calibration setup is illustrated in Fig. 3.7.4 Raise the moveable platen such that the non-moveableplaten is in cont
30、act with the top bearing plate. Apply a pre-loadsufficient to provide full contact between the bearing plates andthe spacers, equivalent to 10 psi (0.07 MPa) over the gross areaof the flatjack.7.5 The distance between platens must be held constantduring the calibration procedure. Fix the displacemen
31、t of thetest machine at this point if using a displacement-controlmachine. If not, attach displacement gages (mechanical orelectrical) such that the distance between platens established byFIG. 1 Flatjack Configurations (Plan View)FIG. 2 Flatjack Test Setup for In Situ Stress MeasurementC1196092the p
32、rocedures of paragraph 7.4 can be held constant whenusing a force-control test machine.7.6 Pressurize and depressurize the flatjack three times overthe full operating pressure range. Do not exceed the maximumflatjack operating pressure.7.6.1 While holding the distance between the platens con-stant,
33、increase the pressure in the flatjack in equal incrementsto within 5 percent of the maximum flatjack operating pressure.Use at least 10 equal increments between 0 psi and themaximum flatjack operating pressure. At each increment,record flatjack hydraulic pressure and force applied by the testmachine
34、.7.7 Calculate the load applied by the flatjack as internalpressure times gross flatjack area. Plot flatjack load versus loadmeasured by the test machine with the flatjack load on thehorizontal axis of the plot. The slope of the line is equal to theflatjack constant, that is, the conversion factor:K
35、m5 Pmachine4 Pflatjack(1)7.8 Recalibrate flatjacks after using five times or whendistortion appears excessive.8. Procedure8.1 The location at which compressive stress estimates areperformed is dictated by engineering objectives. The basicarrangement is illustrated in Fig. 2. At the desired location
36、orlocations the following steps should be taken:8.2 Select and mark a visible line on the masonry to definethe location and length of slots to be formed.8.3 Attach at least four pairs of equally spaced gage discs orembedded plugs vertically aligned above and below the slot asshown in Fig. 2. Each ro
37、w of gage points thus formed shall beequally spaced above and below the flatjack. The minimumgage length shall be 0.3 times the length, A, where A is thelength of the flatjack as shown in Fig. 1. The maximum gagelength shall be 0.6 times the length, A, of the flatjack. The firstand last locations sh
38、all be located not less than18 of dimensionAinward toward the center of the slot from each end, as shownin Fig. 2.NOTE 3Alternative instrumentation configurations are acceptable ifcontrolled laboratory tests are conducted to verify the validity of thealternate instrumentation approach. Examples of a
39、lternate configurationsare shown in Fig. 4. These references provide additional information aboutalternate instrumentation for flatjack testing.3, 4, 53Ronca, P., “The Significance of the Gauging System in the Flatjack In-SituStress Test for Masonry: Experimental Investigation,” The Masonry SocietyJ
40、ournal, Vol 14, No. 1, August 1996.4Schuller, M., “Flatjack Methods for Diagnosis of Modern Masonry,” Proceed-ings, On-Site Control and Evaluation of Masonry Structures, Binda, L., deVekey, R.,editors, RILEM, 2001.5Coombs J., Tanner J.E., “Development of Laboratories for Masonry Testing andNon-Destr
41、uctive Evaluation,” The Masonry Society Journal, Vol 26, No. 2, 2008,pp. 9-20.FIG. 3 Flatjack Calibration Setup (Elevation View)FIG. 4 Examples of Alternative Instrumentation ApproachesC11960938.4 Measure the initial distance between each pair of gagepoints.8.5 Prepare the slot (see Note 4) (see Sec
42、tion 6) and recordthe measured slot dimensions and the time. Clean slots of allmortar and brick particles prior to the insertion of flatjacks.NOTE 4The location of the slot shall be at least 112 flatjack lengthsfrom wall openings or ends.8.6 Repeat step 8.4 after the slot has been prepared to obtain
43、the initial deviation from the original gage distances.8.7 Insert the flatjack into the slot. Shim as required toachieve a tight fit and bridge over any interior voids in themasonry. See the Annex for a description of flatjack shims andtheir use.8.8 Connect hydraulic hoses and fill the calibrated fl
44、atjackwith hydraulic oil until pressure begins to develop.8.9 In order to seat the flatjack and any shims, pressurize theflatjack to approximately 50 % of the estimated maximumflatjack pressure (which corresponds to the estimated compres-sive stress in the masonry). Reduce the flatjack pressure toze
45、ro.8.10 Increase pressure in the flatjack to 25 %, 50 %, and75 % of the estimated maximum pressure holding the pressuresteady at each level.At each increment, measure and record thedistance between each pair of gage points. Three repetitions ofdisplacement measurement are required at each gage point
46、. It isrecommended that the test be conducted as soon as possibleafter formation of the slot: the time taken for load applicationshall be approximately equal to the time elapsed since forma-tion of the slot to minimize the effects of creep deformations.8.11 Continue pressurizing until the original g
47、age distancesare restored. The allowable average deviation from the originalgage length shall be the greater of 60.0005 in. (60.013 mm)or120 th of the maximum initial deviation, with no singledeviation exceeding the greater of 60.001 in. (60.025 mm) or110 th of the maximum deviation. Tests in which
48、these limitsare exceeded shall be considered invalid. Record the finalflatjack pressure.8.12 Reduce the flatjack pressure to zero.8.13 A second repetition of 8.10 and 8.11 is recommendedto verify the final flatjack pressure.8.14 Disconnect hoses and remove the flatjack. The slotmay be filled with mo
49、rtar or other suitable material of a colorand strength similar to the original mortar.9. Calculation9.1 Calculate the average compressive stress in the masonry,fm, as:fm5 KmKap(2)where:Km= a dimensionless constant which reflects the geometri-cal and stiffness properties of the flatjack, as deter-mined by Section 7,Ka= the ratio of measured area of the flatjack to theaverage measured area of the slot, andp = flatjack pressure required to restore the gage points tothe distance initially measured between them withinthe tolerance allowed, psi or MPa.10. Report10.1 Report
