What is the seismic design category for "Moderate to high risk level"?

The seismic design categories are defined by the International Building Code (IBC) based on a combination of factors including the geographic region's seismic risk and the type of occupancy of the structures. For moderate to high risk levels, the appropriate seismic design category would be "D," which pertains to buildings that require a higher level of detailing and analysis to ensure they can withstand seismic forces.

Category D is typically assigned to areas with a moderate to high probability of seismic events, where design considerations must account for the potential for significant ground shaking. Buildings in this category would need to incorporate better materials, structural systems, and construction practices to mitigate the risks associated with earthquakes.

The other categories are defined for different levels of seismic risk. Category A applies to areas with very low seismic risk, while E and F pertain to higher seismic risks; however, the specifics of what constitutes "moderate to high" in terms of building codes align more closely with Category D. Therefore, when determining the seismic design category for a region identified as having a moderate to high risk level, D is indeed the correct classification.