Ryan Miller Architects provides seismic assessments conforming to Level 1 Investigation as defined by ASTM E 2026-24, ASTM E 2557-24, and ASCE 41-23. We can also further use ST-RISK software, if required. ST-RISK is an industry-standard software package used to perform site-specific earthquake risk analysis for individual buildings. It is primarily used to calculate a building’s vulnerability to earthquake damage and to generate Probable Maximum Loss (PML) reports for lending and insurance decisions. Our goal is to provide a seismic risk assessment with a low degree of uncertainty.

In special cases, such as high rise buildings in downtown San Francisco or elsewhere designed and constructed in the 1950s or 1960s or displaying structural irregularities, a Level 1 Investigation is supplemented with more refined methods of analysis, such as nonlinear computer analysis. The Level of Investigation is related to the seismic assessment level of uncertainty.

If a building utilizes one or more lateral force resisting systems in its structural configuration we perform separate risk analyses for each system; we estimate a loss value for the building based on the contribution to the loss of each analyzed system. For properties including more than one building, we average the loss values using appropriate methods as well as engineering judgment.

The seismic assessment culminates in the estimation of Scenario Upper Loss (SUL) value. The SUL value is determined for a 475-year ground motion and has a 10% probability of being exceeded or 90% confidence of damage estimate. The PML90 value indicates the maximum damage expected to occur at 9 or 10 buildings that share locational and similar construction characteristics with the subject property. The ASCE 41-23 analysis is based on a 20% probability of exceedance in 50 years