For concrete foundation walls in Seismic Category D, what is the thickness requirement if the wall is no more than 4 feet 6 inches high?

In Seismic Category D, the requirements for concrete foundation walls are designed to ensure structural integrity and safety in areas prone to seismic activity. For a concrete foundation wall that does not exceed a height of 4 feet 6 inches, the minimum thickness requirement is set at 6 inches.

This thickness is established based on various factors including load-bearing capacity, durability, and the need to withstand lateral forces that may be exerted during seismic events. A wall of this thickness is typically sufficient to provide the necessary strength and stability while also accommodating the structural demands placed upon it.

Walls thicker than 6 inches are allowed, as they can offer increased strength and additional safety margins. However, the code specifies 6 inches as the minimum requirement for this specific height, ensuring that even under the duress of seismic activity, the foundation walls retain their functional and structural characteristics important for the safety of the building and its occupants.