1、Designation: C1531 15Standard Test Methods forIn Situ Measurement of Masonry Mortar Joint ShearStrength Index1This standard is issued under the fixed designation C1531; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st 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 These test methods cover procedures for the determina-tion of the average in situ mortar joint shear strength index ine
3、xisting unreinforced solid-unit and ungrouted hollow-unitmasonry built with clay or concrete units. Three methods areprovided:1.1.1 Method A (with Flatjacks Controlling Normal Com-pressive Stress)For determining mortar joint shear strengthindex when the state of normal compressive stress at the test
4、site is controlled during the test using the flatjack methoddescribed in Test Method C1197. Horizontal displacement ofthe test unit is monitored throughout the test. The test setup forMethod A is shown in Fig. 1.1.1.2 Method B (without Flatjacks Controlling NormalCompressive Stress)For determining m
5、ortar joint shearstrength index when using an estimate of the normal compres-sive stress at the location of the test site. Horizontal displace-ment of the test unit is not monitored during this procedure.The test set up for Method B is shown in Fig. 2.1.1.3 Method C (with Flatjack Applying Horizonta
6、l Load)For determining mortar joint shear strength index using anestimate of the normal compressive stress at the location of thetest site, as shown in Fig. 3. Horizontal displacement of the testunit is generally not measured during this procedure.1.2 The values stated in inch-pound units are to be
7、regardedas standard. The values given in parentheses are mathematicalconversions 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
8、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:2C1180 Terminology of Mortar and Grout for Unit MasonryC1196 Test Method for In Situ Compressive Stress Within
9、Solid Unit Masonry Estimated Using Flatjack Measure-mentsC1197 Test Method for In Situ Measurement of MasonryDeformability Properties Using the Flatjack MethodC1232 Terminology of MasonryE4 Practices for Force Verification of Testing Machines2.2 Other Document:International Existing Building Code (A
10、ppendix A, ChapterA1, Seismic Strengthening Provisions for UnreinforcedMasonry Bearing Wall Buildings), 20143ASCE/SEI 41 Seismic Evaluation and Retrofit of ExistingBuildings, ASCE Standard ASCE/SEI 41 (Chapter 11,Masonry)43. Terminology3.1 Terminology defined in Terminologies C1180 andC1232 shall ap
11、ply for these test methods.4. Summary of Test Method4.1 The in-place shear test is used to provide an index of thein situ, horizontal shear resistance of mortar joints in unrein-forced masonry. For Method A, a single masonry unit isremoved from opposite ends of the chosen test unit as shownin Fig. 1
12、. For Method B, a single masonry unit and a head jointare removed from opposite ends of the chosen test unit, asshown in Fig. 2. For Method C, head joints on both ends of thetested unit are removed as shown in Fig. 3. Ensure that the bedjoints are not disturbed in the unit to be tested. The test uni
13、t isthen displaced horizontally relative to the surrounding masonryusing a hydraulic jack or specialized flatjacks. The horizontal1These test methods are under the jurisdiction of ASTM Committee C15 onManufactured Masonry Units and are the direct responsibility of SubcommitteeC15.04 on Research.Curr
14、ent edition approved June 1, 2015. Published July 2015. Originally approvedin 2002. Last previous edition approved in 2009 as C1531 09. DOI: 10.1520/C1531-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of A
15、STMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from International Code Council, 4051 Flossmoor Road, CountryClub Hills, IL 60478.4Available from American Society of Civil Engineers (ASCE), 1801 AlexanderBell Dr., Reston, VA 20191, http:/ww
16、w.asce.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1force required to cause first movement of the test unit providesa measured index of the mortar joint shear str
17、ength.5. Significance and Use5.1 The masonry mortar joint shear strength index obtainedby this test method can be related to the masonry wall shearstrength by relationships contained in referenced Codes andStandards. For example, Chapter A1 of the InternationalExisting Building Code contains a formu
18、la relating shear indexto wall shear strength, while a slightly different formula can befound in Chapter 11 of ASCE/SEI 41. The user of this standardis cautioned that these shear strength relationships are typicallyempirical relationships based on tests of early 20th-centuryunreinforced brick masonr
19、y. These relationships typically as-sume that wall shear strength is limited by shear of the mortarjoints rather than shear through the units.5.2 For hollow ungrouted or solid unit masonry constructionthe shear strength index is measured only for the mortar bedjoints vertically adjacent to the unit
20、being tested. When testinghollow ungrouted masonry construction, the shear strengthindex is based on the horizontal interface between the mortarand the test unit and the masonry above and below the test unit.In the case of multi-wythe construction, the measured mortarjoint shear strength index is ap
21、plicable only to the wythe inwhich the test unit is located; no headers shall exist immedi-ately above or below the test unit. The contribution of anyexisting collar joint mortar to the measured shear strengthindex is neglected, and this may lead to an overestimate of theshear strength index (see No
22、te 1).NOTE 1Some documents that reference this test method, includingASCE/SEI 41, include a reduction factor to account for the contribution ofa filled collar joint to the measured shear strength index.5.3 The test procedure listed for Method A may be con-ducted as an extension of Test Method C1197.
23、 The two-flatjacktest, conducted in accordance with Test Method C1197, pro-vides half of the required test setup for Method A. At thecompletion of both the C1197 and the C1531 Method A test,one would know the deformability of the masonry at the testand the relationship between the expected joint she
24、ar strengthindex and the normal compressive stress.6. Apparatus6.1 The following equipment is required for both Method Aand Method B:FIG. 1 Test SetupMethod AFIG. 2 Test SetupMethod BFIG. 3 Test SetupMethod CC1531 1526.1.1 Equipment to measure load; two options exist: (1)Ahydraulic jack with an appr
25、opriate working pressure range toload the test unit. The force output of the jack throughout itsworking pressure range shall be known, to facilitate conversionbetween hydraulic pressure and force applied to the masonry;(2) For more precision, use a load cell to measure the forceapplied by the hydrau
26、lic jack. Verify load in accordance withPractices E4. Place the load cell between the spherical seat andthe bearing plate nearest the test unit.6.1.2 Steel bearing plates shall be provided at each end ofthe test jack to distribute the load uniformly across the ends ofthe test unit and the reaction u
27、nit as shown in Fig. 1. Thebearing plates shall have a minimum thickness equal to18 thevertical dimension of the bearing plate. The bearing plates shallhave a vertical dimension that is18 in. (3.2 mm) less than theheight of the unit; the plate shall be centered vertically on theend of the unit. The
28、bearing plate shall have a horizontaldimension that equals or exceeds the thickness of the unit. Thebearing plate surface in contact with the loaded unit shall befaced with a neoprene pad116 in. (1.6 mm) thick; the pad shallhave a durometer hardness in the range of 50 to 60.6.1.3 An electrically or
29、manually operated hydraulic pumpwith hydraulic hoses to pressurize the loading jack. Measurepressure using gauges calibrated to a traceable standard havingboth an accuracy of 1 % of full hydraulic scale and anappropriate operating range. The pressure gage shall have apeak hold feature to indicate th
30、e maximum hydraulic pressureattained during specimen loading. The hydraulic system shallbe capable of maintaining constant pressure within 1 % of fullscale for at least 5 min.6.2 The following additional apparatus is required forMethod A:6.2.1 Flatjacks and associated equipment to measure thestate o
31、f compressive stress as described in Test Method C1196.Test Method C1197 describes apparatus necessary to apply aknown state of normal compressive stress to the masonry at thetest site using flatjacks.6.2.2 Use mechanical extensometers or electronic devices tomeasure horizontal displacement of the u
32、nit. The method ordevice used to measure deformation shall be capable ofdeformation measurements up to14 in. (6 mm). Deformationmeasurements shall have an accuracy of at least 0.005 % ofgage length. Fasten brackets or other attachment devicessecurely to the surface of the masonry using a rigid adhes
33、ive.6.3 The following equipment is required for Method C:6.3.1 A small rectangular flatjack that is sized to fit in thehead joint on one side of the test unit. The flatjack dimensionsmust not exceed the dimensions of the end of the tested unit toprevent load application to the mortar joints.6.3.2 If
34、 load-deformation data are required, use instrumen-tation as described in 6.2.2.7. State of Normal Compressive Stress7.1 The magnitude of normal compressive stress will have adirect effect on the measured joint shear strength index andmust be determined beforehand.7.2 Method A (with Flatjacks Contro
35、lling Normal Compres-sive Stress)Apply normal compressive stress using flatjacks.Place an upper flatjack two courses above and centered overthe test unit to within a tolerance of 618 in. (3 mm). Place alower flatjack five courses below the upper flatjack, centeredunder the test unit to within a tole
36、rance of 618 in. (3 mm). Asingle masonry unit, located on the centerline midway betweenthe two flatjacks, is the unit to be tested for measurement ofjoint shear strength. The slots and flatjack installation shall bein accordance with Test Method C1197.7.3 Method B (without Flatjacks Controlling Norm
37、al Com-pressive Stress)Estimate and record the average normalcompressive stress on the unit based upon the location of thetest unit in the structure and the estimated dead and acting liveloads.NOTE 2Estimates of normal compressive stress typically assumeuniform stress distributions that often result
38、 in overestimates of normalstress and corresponding underestimates of shear index. The effects ofinaccurate dead and acting live load estimation can be minimized bylocating tests beneath windows, beneath other wall openings, near the topsof walls, or in other areas with minimal load.7.4 Method C (wi
39、th Flatjack Applying Horizontal Load)Estimate the average normal compressive stress using themethod described in 7.3.8. Preparation of Test Site8.1 The location at which the joint shear strength index ismeasured is dictated by engineering objectives. Avoid areas inwhich the mortar joints appear to b
40、e nonparallel. The unit to betested must be in the stretcher orientation. Locate the test sitefar enough from wall openings or ends so that the loading jackbears against enough masonry to resist forces generated duringloading of the test unit. The basic arrangement is illustrated inFig. 1 for Method
41、 A, in Fig. 2 for Method B, and in Fig. 3 forMethod C. At the desired location the following steps must betaken to prepare the site for testing:8.1.1 For Method A or Method B, provide a space for theloading jack by removing a unit on one end of the test unit. Donot remove a unit for Method C.8.1.2 F
42、or Method A, if the joint shear strength index inopposite directions is to be determined, remove the unit at bothends of the test unit to isolate the joints being investigated.Otherwise, follow the procedure of 8.1.3. The mortar in thejoints above and below the test specimen shall not extendbeyond t
43、he vertical ends of the unit being tested.8.1.3 For Method B, remove a masonry unit on one side ofthe test unit and the head joint on the opposite end of the testunit. The mortar in the joints above and below the testspecimen shall not extend beyond the vertical ends of the unitbeing tested.8.1.4 Fo
44、r Method C, remove the head joints on both ends ofthe test unit. The mortar in the joints above and below the testunit shall not extend beyond the vertical ends of the unit beingtested.8.2 For solid unit and solid grouted masonry construction,measure the width and length at the top and bottom of the
45、 testunit to an accuracy of132 in. (0.8 mm). For hollow ungroutedmasonry construction, measure the length at mid-height ofeach face to an accuracy of132 in. (0.8 mm) and measure theC1531 153minimum thickness of each face shell at a point12 in. (12.7mm) above the mortar-bed plane to an accuracy of132
46、 in. (0.8mm).9. Procedure9.1 Method A (with Flatjacks Controlling Normal Compres-sive Stress):9.1.1 Instrument the test unit by attaching a dial gage orelectronic displacement transducer as shown in Fig. 1. Placethe loading jack, spherical seat, and bearing plates with bearingpads into the space nex
47、t to the test unit. Shim the jack toprovide a centered horizontal force on the test unit.9.1.2 Set the pressure in the two flatjacks equal to 10 psi(0.07 MPa) or less and close the valve. Increase pressure in thehorizontal loading jack gradually, such that failure of the jointoccurs between 30 s and
48、 2 min after initial loading, recordingdisplacement of the unit at small increments of horizontal load.Monitor the flatjack pressure during loading and adjust theinternal pressure, if necessary, to provide a constant normalcompressive stress. When the bond between the unit andmortar joints is broken
49、, the unit will begin to displace continu-ously under constant horizontal load. This represents themaximum horizontal load for this level of normal compressivestress.9.1.3 Increase the pressure in the flatjacks to induce the nextdesired level of normal compressive stress and repeat theprocess of horizontal loading until the maximum horizontalload for this level of normal compressive stress is reached.Repeat the sequence in this manner to determine the bed jointshear stress at various levels of normal compressive stress.9.1.4 To investigate the effect of shear
