Damage on the downstream side, up to a certain depth, is mainly due to thermal variations. The user can define a point of rotation, other than the downstream point of the foundation, using the window shown in Figure 78. This window is activated by the D/S Rotation Point command available in the Spillway window. This rotation point is used to evaluate the downstream overturning safety factor.

Figure 78 

The definition of the pressure distribution over the free-fall spillway is given in section Pressure distribution over free-fall spillway.