where the I/ is the angle to the vertical axis and varies between h/2. This assumption
adds a considerable degree of complexity to the calculation of SFFOR and only
increases the SFFOR by about 10 to 29%. Note that if rg < (h - y)/2, the shielding
angle is negative per Eq. 20 (see the next section). Considering the distribution of the
stroke angle, as a limit, near-horizontal strokes could occur.
The definition of a negative shielding angle is illustrated in Fig. 9.