Chemistry & Biochemistry Research Works
Permanent URI for this collectionhttp://hdl.handle.net/1903/15
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Item Quantifying modeling uncertainties in seismic analysis of dams: Insights from an international benchmark study(Wiley, 2023-12-19) Hariri-Ardebili, Mohammad AminAdvances in nonlinear dynamic analysis of dams have not completely resolved concerns over modeling confidence and analysis accuracy. Verification and validation offer accuracy assessment, but uncertainties persist during performance evaluation due to both epistemic (modeling) and aleatory (parametric) sources. Epistemic uncertainties arise from simplifications and modeling techniques. This paper addresses epistemic uncertainties in a gravity dam seismic analysis using data from the International Comnission on Large Dams (ICOLD) benchmark study. While the benchmark formulation included the finite element model of the dam, mechanical material properties, and dynamic loads, participants retained the flexibility to opt for best-practice modeling assumptions, simplifications, and other specifics. Notable response variability emerged, particularly in crack profiles and damage predictions. This study examines sources of variability, quantifying modeling uncertainty for the benchmark problem. More specifically, the modeling variability is quantified using the logarithmic standard deviation, also known as dispersion. This metric enables its incorporation into other seismic risk assessment and fragility studies. Under relatively low-intensity motion (peak ground acceleration [PGA] of 0.18 g in this case), modeling dispersion of 0.45, 0.30, 0.32, and 0.30 were calculated for the maximum dynamic crest displacement, maximum hydrodynamic pressure at the heel, heel and crest maximum acceleration, respectively. Additionally, the dispersion of the failure PGA was determined to be 0.7. Findings underscore the need for systematic seismic response modeling in dam engineering to enhance prediction accuracy. A better understanding of the sources and magnitudes of modeling uncertainties can help improve the reliability of dam seismic analysis and contribute to the development of more effective risk assessment and mitigation strategies.Item Comments regarding “Seismic damage analysis due to near-fault multipulse ground motion” by Guan Chen, Jiashu Yang, Ruohan Wang, Kaiqi Li, Yong Liu, Michael Beer; Earthquake Engineering & Structural Dynamics, 2023(Wiley, 2023-11-27) Hariri-Ardebili, Mohammad AminThis discussion is based on the paper by Chen et al. in 2023 (hereafter referred to as “the original paper/authors”). In their study, the original authors conducted a series of analyses using nonpulse, single-pulse, and multipulse ground motion records, evaluating their impact on a frame structure, a slope, and a gravity dam. Their key finding suggests that multipulse ground motion leads to more severe structural damage compared to nonpulse and single-pulse ground motions. However, it is important to note that the seismic damage analysis of the gravity dam in this paper does not adhere to state-of-the-practice recommendations. Consequently, drawing a definitive conclusion regarding the influence and importance of multipulse ground motion records on the seismic response of concrete dams requires further justification. This necessitates the incorporation of high-fidelity numerical models and probabilistic performance evaluation. We will discuss the significance of modeling assumptions, specifically addressing the dam–rock dynamic interaction in crack propagation and failure in dams.