For an abutment with a spill-through slope:
Kt = 0.55 +0.05 (1/(SF) - 1)Where the shape factor (SF) = X1/X2
For abutments with wing-walls:
Kt = 0.82 + 0.02((1/(SF) - 1)Where the shape factor (SF) = X1/X2
For vertical wall abutments,
Kt = 1.0For all abutments shapes, If SF<0.1, then Kt=1.0