A multi‐objective performance‐based seismic design framework for building typologies. (18th February 2022) - Badal, Prakash S.
Abstract: A vast majority of the world's reinforced concrete (RC) buildings are designed using prescriptive force‐based methods. In addition to safety, there is growing demand to meet additional performance objectives to limit economic losses and minimize disruption after smaller earthquakes. A framework is proposed that allows prescriptive design standards to deliver multi‐objective risk targets. It adopts an explicitly probabilistic approach considering uncertainty in seismic demand and structural capacity. A rational basis for targeting multiple performance metrics is actualized. The framework provides the first step of a practical strategy to migrate to the performance‐based design of buildings in a phased manner. Using the framework, risk‐targeted safety factors (RTSF) are derived in conjunction with the prescriptive design method to meet different target risk spaces. The framework proposes the replacement of importance factor, which does not quantify performance or risk or considers the building typology, with RTSFs. The framework is illustrated using six example RC buildings representing special moment frame typology conforming to prevalent Indian standards. The results indicate that such typology has an annual frequency of collapse of 1 × 10 −4, an annual loss‐of‐operationality of 20 × 10 −4, and an expected annual loss of 3 × 10 −4 . For the same typology, a four‐fold reduction requires an RTSF value of 1.6 for collapse risk, whereas the risk of loss‐of‐operationality necessitates a larger RTSF of 2.0. The larger RTSFs for higher performance illustrates additional design requirement that can only be obtained when considering multiple performance objectives. The framework is universally applicable for any lateral load‐resisting system and selected performance metrics.