Risk based approach to PML estimation for single-storey reinforced concrete industrial buildings and its impact on earthquake insurance rates

Abstract

Estimating earthquake losses is an important issue for many private and public bodies. As a major stakeholder, insurers need realistic Probable Maximum Loss (PML) values to foresee the possible losses they would face after a major earthquake and also to calculate optimal insurance premiums. Insurers generally use fragility curves to manage their portfolio by calculating overall PML values. There are, however, serious impacts of risk based PML estimation on earthquake insurance rates, and in this respect fragility curves, which represent regional losses rather than individual losses, could lead to suboptimal decisions. In this study, a rapid earthquake loss estimation methodology is proposed for single-storey reinforced concrete industrial buildings based on parameters determined after investigating more than 80 industrial building projects in Turkey. 384 analytical structural loss estimation curves were obtained via the non-linear structural performance analysis method proposed in the 2007 Turkish Seismic Design Code. To provide a detailed evaluation of the proposed methodology’s performance, fragility curves representative of the structural types and the design levels of the buildings investigated were also developed. Finally, total insurance premiums corresponding to PML values of the inventory buildings were calculated, using the two aforementioned estimation methods and others previously published, by addressing issues such as reinsurance cost, capital cost and profit. Results reveal considerable differences in PML values and eventually earthquake insurance rates for the buildings investigated between the risk based structural loss estimation method and the existing methods, indicating possibilities for improved portfolio analysis and management tools.