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1、International Standard 6891 INTERNATIONAL ORGANIZATION FOR STANDARDlZATION*MEWYHAPOAHAR OPAHH3Al b) equipment to measure joint slip under load with an ac- curacy of + 1 % or better, or for slips of less than 2 mm with an accuracy of f 0,02 mm. The equipment shall en- sure that eccentricities, twist,
2、 etc. have no influence on the measurements.2) 8 Loading procedure 8.1 Estimation of maximum load The estimated maximum load, Fest, for the type of joint to be tested shall be determined on the basis of experience, calcula- tion or preliminary tests, and should be adjusted as required in 8.6, 8.2 Ap
3、plication of load The loading procedure shown in figure 1 should generally be followed. The load shall be applied up to 0,4 Fest and maintained for 30 s. The load shall then be reduced to 0,l Fest and maintained for 30 s. Thereafter the load shall be increased until the ultimate load or slip of 15 m
4、m is reached.31 Below 0,7 Fest a constant rate of load or slip corresponding to 0,2 Fest per minute f 25 % shall be used.,Above 0,7 Fest, a constant rate of slip shall be used; so adjusted that the ultimate load or a slip of 15 mm is reached in 3 to 5 min additional testing time (total testing time
5、about 10 to 15 min). The test may be stopped when the ultimate load is reached, or when the slip is 15 mm. For particular tests, the preload cycle up to 0,4 Fest may be omitted with a corresponding adjustment to the total testing time. 8.3 Measurement of slip The slip measurements vol, vM, v14, vll,
6、 v21, 24, v, and V shown in figure 2 shall be recorded for each test specimen. The slip at maximum load, Fmx, shall also be recorded. When a load/slip diagram is not available, measurements of slip should be taken at each 0,l Fest increment of load (see figure I). 8.4 Measurement of load The load re
7、ached before or at a slip of 15 mm, shall be recorded as the maximum load, Fmax, for each specimen. 1) Test methods for joints made with punched metal plate fasteners, nails and staples will form the subject of future International Standards. 2) Equipment that can continuously record load and slip i
8、s recommended; exceptionally, slips may be measured at chosen load levels provided the measurements can be made without significantly influencing the continuity of load application. A sufficient number of load levels should be chosen to ensure that the calculations (see 8.5) and the adjustments (see
9、 8.8) can be made. 3) The requirement that the load be maintained constant for 30 sat 0,4 and 0,l Fest is to permit adequate time for the loading to be reversed, it is not intended to provide information on creep behaviour. 2 Copyright International Organization for Standardization Provided by IHS u
10、nder license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 22:11:42 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 6891-1983 (El I,0 ot9 018 0,7 u Figure 1 - Loading.procedure Time, min 0 Joint slip, v Figure 2 - Idealized load-defo
11、rmation curve and measurements 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 22:11:42 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 6891-1983
12、(El 8.5 Calculations From the recorded measurements, the following values, if rele- vant, shall be determined for each test : 1) maximum load F IllSX 2) estimated maximum load F est 3) initial slip Vi = VW 4) modified initial slip 5) joint settlement11 6) elastic slip v, = yi - Vi,mod 2 Ve =3(vt4 +
13、V24 - Vll - v211 7) initial slip modulus ki = 0,4 Festlq 8) slip modulus ke = OA b) quality, strength properties and surface finish of the materials of the fasteners (including anti-corrosive protec- tion); c) dimensions of the joints, size and number of fasteners, details of gaps between members; d
14、) conditioning of timber and test specimens before and after manufacture, moisture content of the timber at manufacture and at test, fissures etc; e) the loading procedure used (by reference to this Inter- national Standard) and a statement of any deviations; f) individual test results and any relev
15、ant information regarding adjustments, mean values and standard devia- tions, and descriptions of the modes of failure. 1) It should be noted that many load-slip curves are initially convex upwards so that v, will be negative. 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 22:11:42 MDTNo reproduction or networking permitted without license from IHS -,-,-