The REDi Rating System: A Framework to Implement Resilience-based Earthquake Design for New Buildings

Abstract

The earthquake performance expectation of national building codes – which has not changed for many decades – is to provide ‘life safety’ for building occupants in a design level earthquake; the code accepts that building damage is likely to occur and may not be economically repairable. Even those buildings which are designed to minimize structural damage through a performance-based seismic design approach are likely to have significant damage to architectural components and facades, MEP equipment, and building contents. The consequences of this damage are direct economic losses from earthquake repairs and indirect losses – such as business interruption, the loss of culture and sense of community, and quality of life – due to downtime. With the support of stakeholders and multi-disciplinary design professionals, we have developed a comprehensive Resilience-based Earthquake Design Initiative (REDi) Rating System. It is written as a set of guidelines to help stakeholders better understand earthquake risks and presents a single integrated and actionable framework for owners, architects and engineers to achieve much higher seismic resilience objectives than are embodied in code designs. For example, a REDi Platinum building aims to be operational within 3 days after a major earthquake compared to code-designed buildings which may not regain functionality for more than a year according to some of the latest research. The REDi resilience objectives are achieved through adopting design and planning measures in each of three Resilience Categories – Building Resilience, Organizational Resilience, and Environmental Resilience. Some of the measures are mandatory, others are recommendations which may be selected depending on the type of facility and the Rating level being targeted. The success of the resulting design in meeting quantitative loss and downtime objectives is then demonstrated by performing a FEMA P-58 based Loss Assessment. Building Resilience focuses on minimizing damage to structural and non-structural components through enhanced design such that only minor repairs may be required. Organizational Resilience addresses contingency planning for utility disruption, to maintain livable conditions and business continuity. It also introduces concepts to reduce downtime associated with delays to repairs (such as access to post-disaster financing, and contractor and engineer mobilization). Finally, Environmental Resilience addresses site considerations which can help to minimize site access restriction and damage to the building from external earthquake-induced hazard such as tsunamis or surrounding buildings. The REDi framework is suitable for future adaptation to achieve resilience against any type of extreme event, including floods, hurricanes, terrorism, and climate change.