PY curves are either generated for static or cyclic conditions, the static or cyclic option is controlled within the lateral soil input tab. By default it is set to CYCLIC. Whether a particular method is affect by the static or cyclic option is shown in the Lateral_Soil_Methods table.
The PY can be changed by the use of modifiers, which can be applied either to the lateral pressure (P) or to the displacement (Y) part of the curve. For instance a Y modifier could be used to soften lateral response by applying a YMod of greater than 1.0 to the PY curves. The PY curve modifiers are only applied during the finite element analyses of the pile and not in the PY curves which are output.
Y shifts can be added to the PY curves under the lateral input tab. Y shifts may be applicable where it is necessary to model loss of soil contact with the pile, or to model the effect of a landslide on a pile. It is first necessary to ensure that the “Allow Y shifts” checkbox is checked, this then allows an extra column in the lateral soil input table. A Y shift is an optional parameter for each layer and if no value is entered then no change is made to the PY curve.
Lateral parameters which are specific to a method are discussed in the relevant sections (e.g. Xr in the CLAYAPI method).