Risk-Targeted Seismic Design Maps with Aleatory and Epistemic Uncertainty in Tehran and Surrounding Areas

Abstract

ABSTRACT This study aims to introduce a risk-targeted probabilistic model that facilitates seismic design hazard mapping. Here, we investigate how to incorporate hazard regional variations and different structural fragility typologies so as to achieve a uniform target risk across the map. This paper takes Tehran, the capital city, and its surrounding area as a case study and explores the highly digitized hazard curves conditioned on the time-dependent occurrence of an earthquake at a 50-year exposure time. We introduce a new set of parameterized quantile functions for Risk-targeted design Intensity Measure (IMR) as the seismic design hazard. A group of IMR maps is subsequently prepared based on a 1% collapse probability during the next 50-year lifetime. Furthermore, the quantile function corresponding to each fragility type is able to show the aleatory uncertainty at each site on the region map. The uncertainty maps illustrate relatively less inherent variability than what exists in the hazard curves themselves. Then, we tackle the source of uncertainty arising from percentile hazard curves into IMR, known as epistemic uncertainty, by deriving a new closed-form expression, which allows for a sampling-free estimation of the epistemic uncertainty. The risk-targeted seismic design hazard with its accompanying uncertainties can lead to a promising seismic design hazard with potential applications for the insurance industry, urban planners, and risk-aware building owners.