Stress Integration Approach in Resonant Column and Torsional Shear Testing for Soils

Stress integration approach to evaluate damping ratio in torsional tests

“…Figure 3 presents the R eq based on damping ratio with the modified hyperbolic model using different curvature coefficients. Rotations are normalized with respect to reference rotation, θ r 2. As shown in Figure 3, the ranges of R eq value are wider at high strains.…”

“…A more general approach to account for nonuniform stress–strain than the conventional equivalent radius approach, the stress integration approach was developed 2. The nonuniform stress–strain was accounted for more precisely by integrating the stress over the radius of soil specimen to obtain a twist–torque relationship.…”

“…The nonuniform stress–strain was accounted for more precisely by integrating the stress over the radius of soil specimen to obtain a twist–torque relationship. Using closed‐form integration with hyperbolic model, a theoretical twist–torque relationship was developed by Sasanakul and Bay 2.…”

“…At a given rotation, T 1 can be obtained from the closed‐form integration of the twist–torque relationship 2. By linearizing the problem, T 2 can be determined using the following equation: where G = 2· D min· G eff .…”

“…Evaluation of damping requires identification of a specific strain associated with the effective damping ratio at a given twist. Hence, attempts have been made to deal with nonuniform stress–strain effects occurring over the radius of soil specimen in the resonant column and torsional shear (RC/TS) test with an equivalent radius approach by Chen and Stokoe 1 and stress integration approach by Sasanakul and Bay 2.…”