Half disp. range means to consider an "amplitude" only in the analysis (e.g. reversing +/-10mm disp, consider 10mm only in analysis; NOT 20mm). Read ASME-III-NB/NC, stated for "reversing and non-reversing" dynamic loads, consider half-disp. range only (an amplitude).
In Full Displacement stress range, we have to considered Temperature (T1), hog (D1), Sag (D2), Structural Displacement in X dir (D3), Structural Displacement in Y dir (D4),How we considered the load case for the above conditions