@article{kwag_gupta_baugh_kim_2021, title={Significance of multi-hazard risk in design of buildings under earthquake and wind loads}, volume={243}, ISSN={["1873-7323"]}, DOI={10.1016/j.engstruct.2021.112623}, abstractNote={• Development of a performance-based framework to consider multiple hazards. • Significance of multi-hazard design is shown through retrofit solutions in buildings. • Cost-effective damper design is explored under two different hazards. Traditionally, external hazards are considered in the design of a building through the various combinations of loads prescribed in relevant design codes and standards. It is often the case that the design is governed by a single dominant hazard at a given geographic location. This is particularly true for earthquake and wind hazards, both of which impart time-dependent dynamic loads on the structure. Engineers may nevertheless wonder if a building designed for one of the two dominant hazards will satisfactorily withstand the other. Prior studies have indicated that in some cases, when a building is designed for a single dominant hazard, it does not necessarily provide satisfactory performance against the other hazard. In this paper, we propose a novel framework that builds upon performance-based design requirements and determines whether the design of a building is governed primarily by a single hazard or multiple hazards. It integrates site-dependent hazard characteristics with the performance criteria for a given building type and building geometry. The framework is consistent with the burgeoning area of probabilistic risk assessment, and yet can easily be extended to traditional, deterministically characterized design requirements as illustrated herein.}, journal={ENGINEERING STRUCTURES}, author={Kwag, Shinyoung and Gupta, Abhinav and Baugh, John and Kim, Hyun-Su}, year={2021}, month={Sep} }
 @article{ryu_kwag_ju_2018, title={Fragility Assessments of Multi-Story Piping Systems within a Seismically Isolated Low-Rise Building}, volume={10}, ISSN={["2071-1050"]}, DOI={10.3390/su10103775}, abstractNote={A successful, advanced safety design method for building and piping structures is related to its functionality and sustainability in beyond-design-basis events such as extremely strong ground motions. This study develops analytical models of seismically isolated building-piping systems in which multi-story piping systems are installed in non-isolated and base-isolated, low-rise buildings. To achieve the sustainable design of a multi-story piping system subjected to strong ground motions, Triple Friction Pendulum (TFP) elements, specifically TFP bearings, were incorporated into the latter building structure. Then, a seismic fragility analysis was performed in consideration of the uncertainty of the seismic ground motions, and the piping fragilities for the seismically non-isolated and the base-isolated building models were quantified. Here, the failure probability of the piping system in the non-isolated building was greater than that in the seismically isolated building. The seismic isolation design of the building improved the sustainability and functionality of the piping system by significantly reducing the seismic energy of extreme ground motions which was input to the building structure itself.}, number={10}, journal={SUSTAINABILITY}, author={Ryu, Yonghee and Kwag, Shinyoung and Ju, Bu-Seog}, year={2018}, month={Oct} }
 @article{kwag_gupta_dinh_2018, title={Probabilistic risk assessment based model validation method using Bayesian network}, volume={169}, ISSN={["1879-0836"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85030567554&partnerID=MN8TOARS}, DOI={10.1016/j.ress.2017.09.013}, abstractNote={Past few decades have seen a rapid growth in the availability of computational power and that induces continually reducing cost of simulation. This rapidly changing scenario together with availability of high precision and large-scale experimental data has enabled development of high fidelity simulation tools capable of simulating multi-physics multi-scale phenomena. At the same time, there has been an increased emphasis on developing strategies for verification and validation of such high fidelity simulation tools. The problem is more pronounced in cases where it is not possible to collect experimental data or field measurements on a large-scale or full scale system performance. This is particularly true in case of systems such as nuclear power plants subjected to external hazards such as earthquakes or flooding. In such cases, engineers rely solely on simulation tools but struggle to establish the credibility of the system level simulations. In practice, validation approaches rely heavily on expert elicitation. There is an increasing need of a quantitative approach for validation of high fidelity simulations that is comprehensive, consistent, and effective. A validation approach should be able to consider uncertainties due to incomplete knowledge and randomness in the system's performance as well as in the characterization of external hazard. A new approach to validation is presented in this paper that uses a probabilistic index as a degree of validation and propagates it through the system using the performance-based probabilistic risk assessment (PRA) framework. Unlike traditional PRA approaches, it utilizes the power of Bayesian statistic to account for non-Boolean relationships and correlations among events at various levels of a network representation of the system. Bayesian updating facilitates evaluation of updated validation information as additional data from experimental observations or improved simulations is incorporated. PRA based framework assists in identifying risk-consistent events and critical path for appropriate allocation of resources to improve the validation.}, journal={RELIABILITY ENGINEERING & SYSTEM SAFETY}, author={Kwag, Shinyoung and Gupta, Abhinav and Dinh, Nam}, year={2018}, month={Jan}, pages={380–393} }
 @article{kwag_gupta_2017, title={Probabilistic risk assessment framework for structural systems under multiple hazards using Bayesian statistics}, volume={315}, ISSN={["1872-759X"]}, DOI={10.1016/j.nucengdes.2017.02.009}, abstractNote={Conventional probabilistic risk assessment (PRA) methodologies (USNRC, 1983; IAEA, 1992; EPRI, 1994; Ellingwood, 2001) conduct risk assessment for different external hazards by considering each hazard separately and independent of each other. The risk metric for a specific hazard is evaluated by a convolution of the fragility and the hazard curves. The fragility curve for basic event is obtained by using empirical, experimental, and/or numerical simulation data for a particular hazard. Treating each hazard as an independently can be inappropriate in some cases as certain hazards are statistically correlated or dependent. Examples of such correlated events include but are not limited to flooding induced fire, seismically induced internal or external flooding, or even seismically induced fire. In the current practice, system level risk and consequence sequences are typically calculated using logic trees to express the causative relationship between events. In this paper, we present the results from a study on multi-hazard risk assessment that is conducted using a Bayesian network (BN) with Bayesian inference. The framework can consider statistical dependencies among risks from multiple hazards, allows updating by considering the newly available data/information at any level, and provide a novel way to explore alternative failure scenarios that may exist due to vulnerabilities.}, journal={NUCLEAR ENGINEERING AND DESIGN}, author={Kwag, Shinyoung and Gupta, Abhinav}, year={2017}, month={Apr}, pages={20–34} }
 @inproceedings{kwag_gupta_2016, title={Bayesian network technique in probabilistic risk assessment for multiple hazards}, booktitle={Proceedings of the 24th International Conference on Nuclear Engineering, 2016, vol 4}, author={Kwag, S. and Gupta, A.}, year={2016} }