Seismic design of buildings in the context of regions: A case study of a site in Semnan city, Iran

The seismic codes focus on single buildings and ignore the interdependencies between various sectors and infrastructure. This approach cannot ensure resilient communities and ignores essential aspects of seismic risk (e. g., exposure element). This paper proposes a regional-based design (RBD) method that considers the performance of individual components as well as the interactive consequences of their design on the communities. Unlike most studies, the proposed RBD method considers a dynamic behavior for a region/city and utilizes its master plan to model the stochastic variations in the future built environment. The method determines buildings' seismic design requirement (SDR) by considering the building-level and regional goals. Building-level goals address the most important performance objectives (e.g., safety in residential buildings) and should be satisfied for each structural system and occupancy. However, the method satisfies the regional goals for any structural system. This implies that if (hypothetically) all the buildings in a region/city were designed and constructed with only one structural system (e.g., special steel moment resisting frames, SMRFs), the regional goals should be satisfied. The method starts with the determination of the SDRs by satisfying equal building-level objectives for each occupancy in various locations of the region with one structural system. Then, to achieve the regional goals, the calculated SDRs are uniformly raised to improve the performance of the buildings (if required). The method also considers factors other than the buildings/facilities' performance that could affect the achievement of the regional goals (e. g., emergency response capacity). As a proof-of-concept, the proposed method is used in a site in Semnan City, Iran, to determine the SDR of steel SMRFs. The case study shows that there might be situations where elevating the seismic design requirements of the buildings could not guarantee the achievement of some regional goals. Moreover, the results indicate that factors like the design of the built environment could affect regional risks. Therefore, attention to factors other than the buildings' seismic performance is also essential in achieving the regional goals.