Shown below is a brace frame for a four (4) story building with an overall building height of 40 feet. The columns support the vertical loads shown and are supported on spread footings that weigh 15 kips each. Lateral wind load is 8 kips per floor and 4 kips at the roof. Determine the following:
a. What is the overturning factor of safety for the building with the wind loads shown below? Consider that the wind loads can act in either direction. Neglect the height and width of the spread footings.
b. How many floors can be added to the building while maintaining the code required overturning factor of safety of 2.0? Assume the roof supports a wind load of 4 kips and all floors below support a wind load of 8 kips.