Mr. Manu

for you case as below :

L15 L11+L12+L13+L14 (OCC)****

in this case you taken OCC case as L15 : -(win1+win2+win3+win4).

this is not possible. at a time wind from all direction ( north,east,west & south ) not possible. So your last case L15 is not correct to be considered as OCC case.
anyway this is my opinion & exeprts( in this forum) opinion awaited.

Regards,
ajay damle