A seismic design category is a code-based classification that sets seismic design and detailing requirements for a building.
Definition
A seismic design category groups a building into a classification used by applicable codes to establish seismic design and detailing requirements. Determining it involves code-defined inputs, which can include seismic hazard, site conditions, occupancy or risk characteristics, and other building properties. The design team confirms the governing code and project information before applying the classification. Firms may assign responsibility for gathering inputs and documenting the determination differently across structural and geotechnical scopes. The category can affect analysis methods, detailing, coordination, and effort, but it is not a forecast that a specific earthquake will occur or a prediction of damage. It also does not describe the site’s hazard by itself. Owners benefit from identifying the applicable criteria and required inputs early, then carrying the determination consistently into design documents. Requirements depend on the jurisdiction and the code adopted for the project.
How owners use it
- Confirm which project code and jurisdiction govern before using the classification in design criteria.
- Coordinate the building inputs and site information needed for the determination with the structural and geotechnical teams.
- Example: If a project’s code-defined inputs place it in category C, use category C requirements for the applicable design checks.
- Track classification assumptions in the design basis so changes to occupancy or site data can be reviewed.
