1、Designation: C1531 15C1531 16Standard 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 ye
2、ar 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 These test methods cover procedures for the determination of the average in situ mortar joint shear strength in
3、dex in existingunreinforced solid-unit and ungrouted hollow-unit masonry built with clay or concrete units. Three methods are provided:1.1.1 Method A (with Flatjacks Controlling Normal Compressive Stress)For determining mortar joint shear strength indexwhen the state of normal compressive stress at
4、the test site is controlled during the test using the flatjack method described in TestMethod C1197. Horizontal displacement of the test unit is monitored throughout the test. The test setup for Method A is shownin Fig. 1.1.1.2 Method B (without Flatjacks Controlling Normal Compressive Stress)For de
5、termining mortar joint shear strength indexwhen using an estimate of the normal compressive stress at the location of the test site. Horizontal displacement of the test unitis 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
6、Horizontal Load)For determining mortar joint shear strength index using an estimateof the normal compressive stress at the location of the test site, as shown in Fig. 3. Horizontal displacement of the test unit isgenerally not measured during this procedure.1.2 The values stated in inch-pound units
7、are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsi
8、bilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C1180 Terminology of Mortar and Grout for Unit MasonryC1196 Test Method for In Situ Compressive Str
9、ess Within Solid Unit Masonry Estimated Using Flatjack MeasurementsC1197 Test Method for In Situ Measurement of Masonry Deformability Properties Using the Flatjack MethodC1232 Terminology of MasonryE4 Practices for Force Verification of Testing Machines2.2 Other Document:International Existing Build
10、ing Code (Appendix A, Chapter A1, Seismic Strengthening Provisions for Unreinforced MasonryBearing Wall Buildings), 20143ASCE/SEI 41 Seismic Evaluation and Retrofit of Existing Buildings, ASCE Standard ASCE/SEI 41 (Chapter 11, Masonry)43. Terminology3.1 Terminology defined in Terminologies C1180 and
11、 C1232 shall apply for these test methods.1 These test methods are under the jurisdiction of ASTM Committee C15 on Manufactured Masonry Units and are the direct responsibility of Subcommittee C15.04 onResearch.Current edition approved June 1, 2015June 1, 2016. Published July 2015July 2016. Originall
12、y approved in 2002. Last previous edition approved in 20092015 asC1531 09.C1531 15. DOI: 10.1520/C1531-15.10.1520/C1531-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, ref
13、er to the standards Document Summary page on the ASTM website.3 Available from International Code Council, 4051 Flossmoor Road, Country Club Hills, IL 60478.4 Available from American Society of Civil Engineers (ASCE), 1801 Alexander Bell Dr., Reston, VA 20191, http:/www.asce.org.This document is not
14、 an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate
15、. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*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 States14.
16、Summary of Test Method4.1 The in-place shear test is used to provide an index of the in situ, horizontal shear resistance of mortar joints in unreinforcedmasonry. For Method A, a single masonry unit is removed from opposite ends of the chosen test unit as shown in Fig. 1. ForMethod B, a single mason
17、ry unit and a head joint are removed from opposite ends of the chosen test unit, as shown in Fig. 2. ForMethod C, head joints on both ends of the tested unit are removed as shown in Fig. 3. Ensure that the bed joints are not disturbedFIG. 1 Test SetupMethod AFIG. 2 Test SetupMethod BFIG. 3 Test Setu
18、pMethod CC1531 162in the unit to be tested. The test unit is then displaced horizontally relative to the surrounding masonry using a hydraulic jack orspecialized flatjacks. The horizontal force required to cause first movement of the test unit provides a measured index of the mortarjoint shear stren
19、gth.5. Significance and Use5.1 The masonry mortar joint shear strength index obtained by this test method can be related to the masonry wall shear strengthby relationships contained in referenced Codes and Standards. For example, Chapter A1 of the International Existing BuildingCode contains a formu
20、la relating shear index to wall shear strength, while a slightly different formula can be found in Chapter 11of ASCE/SEI 41. The user of this standard is cautioned that these shear strength relationships are typically empirical relationshipsbased on tests of early 20th-century unreinforced brick mas
21、onry. These relationships typically assume that wall shear strength islimited by shear of the mortar joints rather than shear through the units.This test method provides a means of evaluating thehorizontal in-plane shear behavior of mortar joints in existing unreinforced masonry assemblies (see Note
22、 1).NOTE 1The masonry mortar joint shear strength index obtained by this test method can be related to the masonry wall shear strength by relationshipscontained in referencing Codes and Standards. For example, formulas relating shear index to wall shear strength are found in Chapter A1 of theInterna
23、tional Existing Building Code and Chapter 11 of the Seismic Evaluation and Retrofit of Existing Buildings, ASCE Standard ASCE/SEI 41. Theuser of this standard is cautioned that these shear strength relationships are typically empirical relationships based on tests of early 20th-centuryunreinforced b
24、rick masonry. These relationships typically assume that wall shear strength is limited by shear of the mortar joints rather than shear throughthe units5.2 For hollow ungrouted or solid unit masonry construction the shear strength index is measured only for the mortar bed jointsvertically adjacent to
25、 the unit being tested. When testing hollow ungrouted masonry construction, the shear strength index is basedon the horizontal interface between the mortar and the test unit and the masonry above and below the test unit. In the case ofmulti-wythe construction, the measured mortar joint shear strengt
26、h index is applicable only to the wythe in which the test unit islocated; no headers shall exist immediately above or below the test unit. The contribution of any existing collar joint mortar to themeasured shear strength index is neglected, and this may lead to an overestimate of the shear strength
27、 index (see Note 12).NOTE 2Some documents that reference this test method, includingASCE/SEI 41, include a reduction factor to account for the contribution of a filledcollar joint to the measured shear strength index.5.3 The test procedure listed for Method A may be conducted as an extension of Test
28、 Method C1197. The two-flatjack test,conducted in accordance with Test Method C1197, provides half of the required test setup for MethodA.At the completion of boththe C1197C1197 and the C1531C1531 Method A test, one would know the deformability of the masonry at the test and therelationship between
29、the expected joint shear strength index and the normal compressive stress.6. Apparatus6.1 The following equipment is required for both Method A and Method B:6.1.1 Equipment to measure load; two options exist: (1) A hydraulic jack with an appropriate working pressure range to loadthe test unit. The f
30、orce output of the jack throughout its working pressure range shall be known, to facilitate conversion betweenhydraulic pressure and force applied to the masonry; (2) For more precision, use a load cell to measure the force applied by thehydraulic jack. Verify load in accordance with Practices E4. P
31、lace the load cell between the spherical seat and the bearing platenearest the test unit.6.1.2 Steel bearing plates shall be provided at each end of the test jack to distribute the load uniformly across the ends of thetest unit and the reaction unit as shown in Fig. 1. The bearing plates shall have
32、a minimum thickness equal to 18 the verticaldimension of the bearing plate. The bearing plates shall have a vertical dimension that is 18 in. (3.2 mm) less than the height ofthe unit; the plate shall be centered vertically on the end of the unit. The bearing plate shall have a horizontal dimension t
33、hat equalsor exceeds the thickness of the unit. The bearing plate surface in contact with the loaded unit shall be faced with a neoprene pad116 in. (1.6 mm) thick; the pad shall have a durometer hardness in the range of 50 to 60.6.1.3 An electrically or manually operated hydraulic pump with hydrauli
34、c hoses to pressurize the loading jack. Measure pressureusing gauges calibrated to a traceable standard having both an accuracy of 1 % of full hydraulic scale and an appropriate operatingrange.The pressure gagegauge shall have a peak hold feature to indicate the maximum hydraulic pressure attained d
35、uring specimenloading. The hydraulic system shall be capable of maintaining constant pressure within 1 % of full scale for at least 5 min.6.2 The following additional apparatus is required for Method A:6.2.1 Flatjacks and associated equipment to measure the state of compressive stress as described i
36、n Test Method C1196. TestMethod C1197 describes apparatus necessary to apply a known state of normal compressive stress to the masonry at the test siteusing flatjacks.6.2.2 Use mechanical extensometers or electronic devices to measure horizontal displacement of the unit. The method or deviceused to
37、measure deformation shall be capable of deformation measurements up to 14 in. (6 mm). Deformation measurements shallhave an accuracy of at least 0.005 % of gagegauge length. Fasten brackets or other attachment devices securely to the surface ofthe masonry using a rigid adhesive.6.3 The following equ
38、ipment is required for Method C:C1531 1636.3.1 A small rectangular flatjack that is sized to fit in the head joint on one side of the test unit. The flatjack dimensions mustnot exceed the dimensions of the end of the tested unit to prevent load application to the mortar joints.6.3.2 If load-deformat
39、ion data are required, use instrumentation as described in 6.2.2.7. State of Normal Compressive Stress7.1 The magnitude of normal compressive stress will have a direct effect on the measured joint shear strength index and mustbe determined beforehand.7.2 Method A (with Flatjacks Controlling Normal C
40、ompressive Stress)Apply normal compressive stress using flatjacks. Placean upper flatjack two courses above and centered over the test unit to within a tolerance of 618 in. (3 mm). Place a lower flatjackfive courses below the upper flatjack, centered under the test unit to within a tolerance of 618
41、in. (3 mm). A single masonry unit,located on the centerline midway between the two flatjacks, is the unit to be tested for measurement of joint shear strength. Theslots and flatjack installation shall be in accordance with Test Method C1197.7.3 Method B (without Flatjacks Controlling Normal Compress
42、ive Stress)Estimate and record the average normalcompressive stress on the unit based upon the location of the test unit in the structure and the estimated dead and acting live loads.NOTE 3Estimates of normal compressive stress typically assume uniform stress distributions that often result in overe
43、stimates of normal stress andcorresponding underestimates of shear index. The effects of inaccurate dead and acting live load estimation can be minimized by locating tests beneathwindows, beneath other wall openings, near the tops of walls, or in other areas with minimal load.7.4 Method C (with Flat
44、jack Applying Horizontal Load)Estimate the average normal compressive stress using the methoddescribed in 7.3.8. Preparation of Test Site8.1 The location at which the joint shear strength index is measured is dictated by engineering objectives.Avoid areas in whichthe mortar joints appear to be nonpa
45、rallel. The unit to be tested must be in the stretcher orientation. Locate the test site far enoughfrom wall openings or ends so that the loading jack bears against enough masonry to resist forces generated during loading of thetest unit. The basic arrangement is illustrated in Fig. 1 for Method A,
46、in Fig. 2 for Method B, and in Fig. 3 for Method C. At thedesired location the following steps must be taken to prepare the site for testing:8.1.1 For Method A or Method B, provide a space for the loading jack by removing a unit on one end of the test unit. Do notremove a unit for Method C.8.1.2 For
47、 Method A, if the joint shear strength index in opposite directions is to be determined, remove the unit at both endsof the test unit to isolate the joints being investigated. Otherwise, follow the procedure of 8.1.3. The mortar in the joints aboveand below the test specimen shall not extend beyond
48、the vertical ends of the unit being tested.8.1.3 For Method B, remove a masonry unit on one side of the test unit and the head joint on the opposite end of the test unit.The mortar in the joints above and below the test specimen shall not extend beyond the vertical ends of the unit being tested.8.1.
49、4 For Method C, remove the head joints on both ends of the test unit. The mortar in the joints above and below the test unitshall not extend beyond the vertical ends of the unit being tested.8.2 For solid unit and solid grouted masonry construction, measure the width and length at the top and bottom of the test unitto an accuracy of 132 in. (0.8 mm). For hollow ungrouted masonry construction, measure the length at mid-height of each face toan accuracy of 132 in. (0.8 mm) and measure the minimum thickness of each face shell at a point 12 in. (12.7 mm) abov
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