SGH performed nonlinear static pushover analysis following ASCE 41 guidelines. We established performance objectives to provide Life Safety in a 500-year earthquake and Collapse Prevention in a 2500-year earthquake. Highlights of our retrofit design include the following:
Reduced the high drift demand of the soft-story structure by adding eight diagonal braces
Used friction dampers in the braces to limit the force transferred into the existing structure and reduce the demands on brace connections to the existing structure
Improved the building’s tolerance to drift by jacketing concrete columns with steel shells, increasing the ductility
Our approach necessitated a more intensive structural analysis, but allowed us to develop a more cost-effective and constructible solution than could be achieved with code-based procedures and elastic analyses. SGH performed the analysis, design, and production of construction documents for the alternative solution on a expedited schedule to meet the scheduled design completion date.