Design and Assessment of Seismic Resilient Structures by the Endurance Time Method

A framework to calculate a quantitative measure of seismic resilience using the Endurance Time (ET) method is introduced. ET method is a response-history based analysis procedure where structures are subjected to gradually intensifying dynamic excitations and their performance is assessed based on their response at different excitation levels, reducing the required computational effort. First, a prototype hospital building is optimally designed through three distinct design philosophies: Prescriptive design code, Performance based design criteria and Value based seismic design method. In value based design method the design sections of structural elements are assumed as optimization parameters and a design with minimum total cost during its life span is being sought. For each candidate design the damages due to probable earthquakes is estimated by the ET method and the expected cost of damages is calculated using Life Cycle Cost Analysis (LCCA). Next, the resilience of each design in continuous range of hazard intensities are compared introducing “Resilience Curve”. Although the optimization objectives in design process are not based on resiliency measures, the value based design showed the best resiliency in the case of seismic hazards. This methodology and potential benefits when considering the need for moving towards more resilient cities is discussed.