| Soil Spring Generation Method |
Select the method used to generate soil springs. Either supplied values of program generated soil spring values can be used. For program generated, either the Richart-Whitman method or Veletsos method may be selected. These models assume uniform soil conditions throughout the range of interest for the foundation. The program uses horizontal and vertical springs for analysis. Rocking and torsion springs are ignored.
- Direct Input – If soil spring values are provided by a geotechnical engineer, select this option and enter the values in the Soil Spring Stiffness and Damping group.
- Richart-Whitman Method – Vertical and horizontal mass and damping ratios are calculated based on ACI 315.3R-04 clause 4.2.1.1 equations 4-12a and 4-12b. The vertical spring stiffness is calculated based on equation 4-13a and horizontal spring stiffness is calculated based on equation 4-13b.
- Veletsos Method – This method uses soil impedance, where the real () portion of soil impedance indicates soil spring stiffness and the imaginary () portion of soil impedance indicates the damping constant. The damping ratio is calculated from damping constant per ACI 351.3R-04 clause 4.2.1.1 equatoin 4-12a. The vertical spring stiffness is calculated per equation 4-15a and horizontal spring stiffness is calculated per equation 4-15b.
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| Add Effect of Material Damping |
Set this option to consider material damping effect for soil-spring calculations. |
| Soil Properties |
For either of the calculated method of soil spring generation (i.e., Richart-Whitman or Velestos), type the soil property values in the fields. |
| Embedment Impedance |
| Setting | Description |
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| Soil Type |
Select the soil type from the drop-down list. |
| Consider Embedment Impedance |
Set this option to modify soil springs and damping constants due to soil embedment based on ACI 351.3R-04 clause 4.2.3 equations 4-21a and 4-21b. |
| Soil Embedment Depth |
Type a soil embedment depth and select the units of length. |
| Back Fill Shear Modulus |
Type a shear modulus value for the soil in the back fill, in the selected units of pressure. |
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| Soil Spring Stiffness and Damping |
(Direct Input only) If soil spring values have been provided by a geotechnical engineer, type those here. |
