Risk targeted hazard spectra for seismic design in New Zealand (2020)
Type of ContentPosters
- Posters 
AuthorsHorspool, Nick, Elwood, Ken, Gerstenberger, Mattshow all
New Zealand, like many other countries, designs buildings for ground motions with a uniform probability of occurrence such as the 1 in 500-year ground motion. If the expected response of a structure to the design ground motion is known with certainty, then this uniform hazard approach results in uniform risk of exceeding this limit state across a region. However, in reality, structures have uncertainty in their response due to variations in design, construction practices, strength of materials, and code compliance and this variability leads to non-uniform risk across a region. An alternative approach is to use risk targeted hazard spectra that are derived through convolution of hazard curves with representative fragility functions and result in uniform risk across a region. The use of risk targets allows performance objectives of building codes to be set in terms of acceptable levels of risk such as life safety, economic loss and downtime, and be developed with societal input. In this study, risk targeted hazard spectra are developed for New Zealand using multiple risk targets for individual and societal risk at the building and city scale. The results show how risk targeted hazard spectra can be incorporated in the existing NZS1170.5 loading standards with minimal changes. The proposed framework can be used to achieve uniform seismic risk in the building code and design for the performance of individual buildings as well as the performance of cities using multiple risk targets.