i made a plot plan for a new garage

huangyhg

i made a plot plan for a new garage
i made a plot plan for a new garage 20' wide x 18' deep on a r5 type contruction with a pitch roof.
now, buiding & safety requirements in our area (west los angeles, ca 90025) requires that
i have to provide calculation for the size of the metal column to be used (located vertically on both sides of the garage door opening) and the flat bar that will be buried under the slab on the front opening of the garage in which the 2 column (bottom part only) will be bolted together. this for earthquake safety requirement. all 3 sides of the garage has shear wall.
i need the equation to calculate 1) the size of column, 2)the size of flat bar,
3)and also to calculate the rotational stress from the top tip of the garage.