Collaborative recorded data based response studies of four tall buildings in California

Seismic instrumentation, recorded earthquake responses, and collaborative studies of the response records from four tall California buildings are summarized in this summary paper. These buildings include the tallest San Francisco building, the 61-story Salesforce Tower, and the tallest California building, the 73-story Wilshire Grand Tower, as well as a 51-story residential building in Los Angeles and a 24-story government building in San Diego. Various system identification methods are used to analyze the largest earthquake response records retrieved from seismic arrays installed in each of the four buildings. Significant structural dynamics characteristics (fundamental periods and critical damping percentages) are extracted. In general, critical damping percentages for the first mode are <2.5%, consistent with recent studies and recommendations.