RISK-TARGETED SEISMIC DESIGN MAP FOR IRAN: ACHIEVEMENTS AND CHALLENGS

Iran is located in a very high seismic zone. Following the devastating earthquake of Buin-Zahra (Ms7.2) in 1962 which left 12000 deaths, the first draft of Iranian national seismic design code for buildings was presented and updated in 1987 as the first standards for this purpose, referred as Standard No. 2800 (STD-2800). To date, four editions of this code have been published, the latest of which was in 2014 (BHRC, 2014). The current version of STD-2800 employs the Design Basis Earthquake (DBE) based on the uniform hazard philosophy. In recent years, several studies have shown that defining design basis earthquake based on the uniform hazard philosophy does not lead to design of structures with a uniform probability of collapse in different regions. The reasons for this are uncertainty in collapse capacity of structures and differences in the shape of hazard curves (Luco et al., 2007). In this paper, using an algorithm developed by Luco et al. (2007) a new seismic design map referred as risk-targeted seismic design map, has been developed for Iran in order to provide a tool for designing buildings with equal or at least harmonized collapse probability across the country.For the collapse risk assessment of the buildings conforming the STD-2800, same hazard curves resulted in the seismic zonation map of the code are required. However, since such models are not available, the seismic hazard curves of the EMME14 project were employed for this purpose. The resulted hazard curves were classified into four seismic zones corresponding to categories of seismicity in STD-2800. Subsequently, using the resulted hazard curves, the PGA values corresponding to 10% probability of exceedance in 50 years (DBE) were obtained for the whole country. A significant difference is observed between the resulted values of PGA based on EMME14 hazard curves and the DBE introduced by STD-2800.

Keywords:

Risk-targeting , Seismic hazard , Fragility function , Seismic design map