The cyclic triaxial modulus and damping test provides parameters that may be considered for use in dynamic, linear and non-linear analytical methods. These test methods are used for the performance evaluation of both natural and engineered structures under dynamic of cyclic loads such as caused by earthquakes, ocean wave, or blast.
One of the primary purposes of these test methods is to obtain data that are used to calculate Youngrsquo;modulus.
Note 18212;The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D 3740
1.1 These test methods cover the determination of the modulus and damping properties of soils in either undisturbed or reconstituted states by either load or stroke controlled cyclic triaxial techniques.
1.2 The cyclic triaxial properties of soil are evaluated relative to a number of factors including: strain level, density, number of cycles, material type, saturation, and effective stress.
1.3 These test methods are applicable to both fine-grained and coarse-grained soils as defined by the unified soil classification system or by Classification D 2487. Test specimens may be undisturbed or reconstituted by compaction in the laboratory.
1.4 Two test methods are provided for using a cyclic loader to determine Young''s modulus (
1.4.1 Test Method AThis test method requires the application of a constant cyclic load to the test specimen. It is used for determining the Young''s modulus and damping under a constant load condition.
1.4.2 Test Method BThis test method requires the application of a constant cyclic deformation to the test specimen. It is used for determining the Young''s modulus and damping under a constant stroke condition.
1.5 The development of relationships to aid in interpreting and evaluating test results are left to the engineer or office requesting the test.
1.6 LimitationsThere are certain limitations inherent in using cyclic triaxial tests to simulate the stress and strain conditions of a soil element in the field during an earthquake.
1.6.1 Nonuniform stress conditions within the test specimen are imposed by the specimen end platens.
1.6.2 A 90 change in the direction of the major principal stress occurs during the two halves of the loading cycle on isotropically confined specimens and at certain levels of cyclic stress application on anisotropically confined specimens.
1.6.3 The maximum cyclic axial stress that can be applied to a saturated specimen is controlled by the stress conditions at the end of confining stress application and the pore-water pressures generated during testing. For an isotropically confined specimen tested in cyclic compression, the maximum cyclic axial stress that can be applied to the specimen is equal to the effective confining pressure. Since cohe......
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