1、Designation: C 1196 04Standard 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 (e) 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 unre
3、inforced solid-unit2masonry. This test method concerns the measurement of in-situcompressive stress in existing masonry by use of thin, bladder-like flatjack devices that are installed in saw cut mortar jointsin the masonry wall. This test method provides a relativelynon-destructive means of determi
4、ning masonry properties inplace.1.2 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of th
5、e user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E 74 Practice for Calibration of Force Measuring Instru-ments for Verifying the Load Indication of Testing
6、Ma-chines3. Summary of Test Method3.1 When a slot is formed in the 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 unti
7、l the original distance between pointsabove and below the slot is restored. 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
8、 contact with the masonry to (b) the bearing areaof the slot.4. Significance 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. Ap
9、paratus5.1 Flatjack:5.1.1 A flatjack is a thin envelope-like bladder 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. Typically configu-rations are shown in Fig. 1.5.1.2 For d
10、etermination of the state of compressive stress,dimension A should be 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
11、 semi-rectangular flatjacks shall be equal to theradius of the circular 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.4Metal
12、 flatjacks suitable for this purpose shall bemade of type 304 stainless steel sheet of 0.024 in. (0.6 mm) to0.048 in. (1.2 mm) in thickness with welded seams along theedges and incorporating hydraulic inlet or outlet ports.5.1.4 Calibrate all flatjacks as described in Section 7 todetermine their pre
13、ssure-applied load characteristics.5.2 Hydraulic SystemAn electrically or manually oper-ated hydraulic pump with hydraulic hoses is required. Hoseconnections shall fit the flatjack inlet port. Measure pressure1This test method is under the jurisdiction of ASTM Committee C15 onManufactured Masonry Un
14、its and is the direct responsibility of SubcommitteeC15.04 on Research.Current edition approved January 1, 2004. Published February 2004. Originallyapproved in 1992. Last previous edition approved in 2003 as C 1196 - 03.2Solid-unit masonry is that built with stone, concrete, or clay units whose neta
15、rea is equal to or greater than 75 % of the gross area.3For referenced ASTM standards, visit the ASTM 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.4A max
16、imum operating pressure of 1000 psi (6.9 MPa) or less is often adequatefor older existing masonry, but flatjacks with higher operating pressures may berequired for more recently constructed buildings. Flatjacks manufactured withflexible polymers that have operating pressure ranges of less than 1000
17、psi (6.9MPa) may be useful for stress measurements in some historic masonry.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.using gages calibrated to a traceable stand
18、ard having both anaccuracy of 1 % of full hydraulic scale and an appropriateoperating range. The hydraulic system shall be capable ofmaintaining constant pressure within 1 % of full scale for atleast 5 min.5.3 Displacement MeasurementMeasure displacementsof the masonry by a mechanical gage extensome
19、ter 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 measurementsshall have an accuracy of at least 60.005 % of gage length.5.4 Gage P
20、ointsUse 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 movement and ensure the required measurement accu-racy. The gage points s
21、hall 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 masonry are normally prepared by removing themortar from masonry bed joi
22、nts to avoid disfiguring themasonry. Remove all mortar in the bed joint, so that pressureexerted by a flatjack shall be directly against the cleanedsurfaces of the masonry units.6.2 The plan geometry of the slot shall be similar to that ofthe flatjack being used. Plan dimensions of the prepared slot
23、shall 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 using a drill, bar,or tool to remove mortar and produce a
24、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 tippedblades to remove all mortar from the slot.7. Calibration
25、7.1 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 a conversionfactor, Km, to relate internal fluid pressure t
26、o 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 E 74.7.3 Place a 2 in. (50 mm) thick steel bearing plate on thelower platen of the compression machine. The bearing plateshall be of sufficient size
27、 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 other edges of the flatjack. The thickness ofthe spacers shall
28、 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. Position the bearing plate/flatjack/shim assembly on thelower
29、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 contact with the top bearing plate. Apply a pre-loadsufficient
30、 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 displacement of thetest machine at this point if using a displacement
31、 controllablemachine. If not, attach displacement gages (mechanical orelectrical) such that the distance between platens established bythe procedures 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 ope
32、rating pressure range. Do not exceed the maximumflatjack operating pressure.7.6.1 While holding the distance between the platens con-stant, increase the pressure in the flatjack in equal incrementsFIG. 1 Flatjack ConfigurationsFIG. 2 Flatjack Test Setup for In Situ Stress MeasurementC1196042to withi
33、n 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.7.7 Calculate the load applied by the flatjack as internalpressu
34、re 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:Km5 Pmachine4 Pflatjack(1)7.8 Recalibrate flatjacks after using fi
35、ve 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 orlocations the following steps should be taken:8.2 Select and ma
36、rk 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 row of gage points thus formed shall beequally spaced above and bel
37、ow 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 shall be located not less than18 of dimensionA inward toward the ce
38、nter of the slot from each end, as shownin Fig. 2.8.4 Measure the initial distance between each pair of gagepoints.8.5 Prepare the slot5(see Section 6) and record the mea-sured slot dimensions and the time. Clean slots of all mortarand brick particles prior to the insertion of flatjacks.8.6 Repeat s
39、tep 8.4 after the slot has been prepared to obtainthe 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
40、Connect hydraulic hoses and fill the calibrated flatjackwith 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
41、in the masonry). Reduce the flatjack pressure tozero.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 ofdispl
42、acement measurement are required at each gage point. 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 deformati
43、ons.8.11 Continue pressurizing until the original gage 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)
44、 or5The location of the slot shall be at least 112 flatjack lengths from wall openingsor ends.FIG. 3 Flatjack Calibration SetupC1196043110 th of the maximum deviation. Tests in which these limitsare exceeded shall be considered invalid. Record the finalflatjack pressure.8.12 Reduce the flatjack pres
45、sure 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 mortar or other suitable material of a colorand strength similar to the original mortar.9. Calculation9.1 Calculate the
46、 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 = flatja
47、ck pressure required to restore the gage points tothe distance initially measured between them withinthe tolerance allowed, psi or MPa.10. Report10.1 Report each in situ stress determination including thefollowing information:10.2 Description of the testing conditions, for example, site,geographical
48、 location, environmental conditions, (for example,temperature), building identification, date of construction (ifavailable), and name of the engineer/technician conducting thetest. Include details of the type and quality of construction.10.3 Identity and description of the specific test location int
49、he structure and reason for the test.10.4 Description and sources (if possible) of the masonrymaterials at the test location including a general conditionstatement, an elevation drawing, and other pertinent materialdata.10.5 Method of forming the slot, a diagram of the slot,adjacent masonry, location of gage points, and all pertinentdimensions.10.6 Description and source of the flatjack used, instrumen-tation, hydraulic system, flatjack installation, that is, use ofshims, and other pertinent information.10.7 Data sheets listing measurements taken at each pres-sure level.10.8
