What are “Sms” and “Sm1” in seismic design?

In seismic design, "Sms" and "Sm1" specifically refer to the adjusted spectral response accelerations for short and long periods, respectively. These values are derived from site-specific parameters and seismic hazard assessments, and they play a crucial role in determining the seismic design forces and displacement for structures.

Sms, or the maximum considered short-period spectral response acceleration, quantifies how a structure responds to short-duration seismic events, typically those that affect structures with periods under 0.6 seconds. Sm1, which represents the maximum considered spectral response acceleration at a one-second period, addresses the structural behavior during longer seismic events. The distinctions between these spectral accelerations help engineers design buildings that can adequately withstand different types of seismic forces depending on their height and mass characteristics.

As a result, understanding these spectral response accelerations allows engineers to appropriately size and reinforce structures to ensure safety and effectiveness during seismic events.