Risk‐targeted seismic design: Prospects, applications, and open issues, for the next generation of building codes

Abstract

Risk-targeted seismic design: Prospects, applications, and open issues, for the next generation of building codesSeismic design targeting a specific failure risk (i.e., seismic structural reliability) has been invoked as the desired landing of building codes for over than half a century now. 1 On one hand, it has been missed, as most codes worldwide are still based on the seismic adaptation of load-resistance factor design, whose limitations are known. Most notably, it does not enable explicitly controlling the failure probability of the designed construction and does not necessarily warrant comparable seismic structural safety among sites with different seismic design hazards. 2 Since reaching a broad consensus around performance-based earthquake engineering (PBEE) 3 more than two decades ago, research is increasingly proposing results about risk-targeted design, suggesting it is a now-viable approach for earthquake practice. On the other hand, the development of building codes may be slow in implementing scientific innovations, waiting for enough time to transpire after these results have been consolidated and formalized.Earthquake Engineering and Structural Dynamics (EESD) dedicates selected issues of the journal, normally no more than two per year, to special topics. The special issue (SI) publication is planned to be attractive to authors and readers. To authors, it should provide a forum to present their work in a publication of related papers on one subject. To readers, it should give a comprehensive overview of a topical subject. The objective of this SI was to be a venue to review the stateof-the-art research about risk-targeted design, present new advancements and/or extensions, set objectives, and propose calibration for application-ready use, and finally discuss open issues. The SI was expected to be a reference about design based on target seismic reliability and risk. It ideally connects to the EESD SI on PBEE of more than twenty years ago, 4 which has published some among the landmarking papers of contemporary earthquake engineering.After the call for papers launched in March 2022, over thirty-five manuscripts were submitted to the issue within the deadline, confirming the current interest in the topic. Eighteen papers were finally accepted after the usual, multipleround, rigorous review process enforced by the journal. The accepted papers come from four of the five dwelled continents, with Africa being the only one not represented, and are authored by some of the most reputed researchers among those currently active in the field, feeding the hope of an impactful issue.The accepted papers revolve around several topics that can be roughly grouped as follows. The works of Badal and Sinha, 5 Ordaz et al., 6 Bodenmann et al.,7 Heresi and Miranda, 8 Bahnu et al., 9 and Franchin and Noto 10 (who present the re-calibration of partial safety factors for the second generation of the European building code), explicitly deal with risk-and reliability-based design methods for the various facets of risk-targete...

Some issues in the practical application of risk‐targeted ground motions

“…8,9 One potential way of alleviating the seismic reliability discrepancy among sites, is to move away from the uniform hazard concept and tailor the design actions for meeting a specific probabilistic performance objective, which a way to achieve so-called risk-targeted design, to which this journal recently dedicated a special issue. 10 This entails choosing an appropriate target rate of failure (often taken as interchangeable with the annual failure probability) to meet said objective, 𝜆 * 𝑓 , and making some a-priori assumptions about the corresponding structural fragility, that is, the conditional probability of failure, given the level of shaking intensity. 11,12 Despite the apparent simplicity of linking the seismic design actions to a risk objective, in practice this approach of deriving, so-called, risk-targeted ground motion (RTGM), presents some issues 13 that this study explores by implementing the original proposal for their derivation by Luco and co-authors, 14 for seven Italian sites.…”