More Like this

1. Probabilistic Calibration and Prediction of Seismic Soil Liquefaction using quoFEM

   Satish, AB; Yi, S; Nair, AS; Arduino, P (September 2022, Springer, Cham)

   Wang, L; Zhang, JM; Wang, R (Ed.)

   Liquefaction under cyclic loads can be predicted through advanced (liquefaction-capable) material constitutive models. However, such constitutive models have several input parameters whose values are often unknown or imprecisely known, requiring calibration via lab/in-situ test data. This study proposes a Bayesian updating framework that integrates probabilistic calibration of the soil model and probabilistic prediction of lateral spreading due to seismic liquefaction. In particular, the framework consists of three main parts: (1) Parametric study based on global sensitivity analysis, (2) Bayesian calibration of the primary input parameters of the constitutive model, and (3) Forward uncertainty propagation through a computational model simulating the response of a soil column under earthquake loading. For demonstration, the PM4Sand model is adopted, and cyclic strength data of Ottawa F-65 sand from cyclic direct simple shear tests are utilized to calibrate the model. The three main uncertainty analyses are performed using quoFEM, a SimCenter open-source software application for uncertainty quantification and optimization in the field of natural hazard engineering. The results demonstrate the potential of the framework linked with quoFEM to perform calibration and uncertainty propagation using sophisticated simulation models that can be part of a performance-based design workflow. 

   more » « less
2. Probabilistic Calibration and Prediction of Seismic Soil Liquefaction Using quoFEM

   Bangalore Satish, A.; Yi, S.-ri; Nair, A.S.; Arduino, P. (September 2022, Proceedings of the 4th International Conference on Performance Based Design in Earthquake Geotechnical Engineering (Beijing 2022))

   Liquefaction under cyclic loads can be predicted through advanced (liquefaction-capable) material constitutive models. However, such constitutive models have several input parameters whose values are often unknown or imprecisely known, requiring calibration via lab/in-situ test data. This study proposes a Bayesian updating framework that integrates probabilistic calibration of the soil model and probabilistic prediction of lateral spreading due to seismic liquefaction. In particular, the framework consists of three main parts: (1) Parametric study based on global sensitivity analysis, (2) Bayesian calibration of the primary input parameters of the constitutive model, and (3) Forward uncertainty propagation through a computational model simulating the response of a soil column under earthquake loading. For demonstration, the PM4Sand model is adopted, and cyclic strength data of Ottawa F-65 sand from cyclic direct simple shear tests are utilized to calibrate the model. The three main uncertainty analyses are performed using quoFEM, a SimCenter open-source software application for uncertainty quantification and optimization in the field of natural hazard engineering. The results demonstrate the potential of the framework linked with quoFEM to perform calibration and uncertainty propagation using sophisticated simulation models that can be part of a performance-based design workflow. 

   more » « less
3. Constitutive modeling of the cyclic loading response of low plasticity fine-grained soils

   https://doi.org/https://doi.org/10.1007/978-981-13-0125-4_1  

   Boulanger, R. W.; Price, A. B.; Ziotopoulou, K. (May 2018, GSIC 2018, Proceedings of GeoShanghai 2018 International Conference: Fundamentals of Soil Behaviours, A. Zhou et al. (Eds.), Springer Nature Singapore Pte Ltd.)

   Calibrations of the PM4Silt constitutive model are presented for two low-plasticity fine-grained soils that exhibit significantly different cyclic loading be-haviors. The PM4Silt model is a stress-ratio controlled, critical state compatible, bounding surface plasticity model that was recently developed for representing low-plasticity silts and clays in geotechnical earthquake engineering applications. The low-plasticity clayey silt and silty clay examined herein were reconstituted mixtures of silica silt and kaolin with plasticity indices (PIs) of 6 and 20. Un-drained monotonic and undrained cyclic direct simple shear (DSS) tests were per-formed on normally consolidated, slurry deposited specimens. Calibration of the PM4Silt model was based on the monotonic and cyclic DSS test data, plus em-pirical relationships for strain-dependent secant shear moduli and equivalent damping ratios. The calibration process and performance of the PM4Silt constitu-tive model are described for each soil. The results illustrate that PM4Silt is capa-ble of reasonably approximating a range of monotonic and cyclic loading behav-iors important to many earthquake engineering applications and is relatively easy to calibrate. 

   more » « less
4. On Suitability of Element Tests to Represent Constitutive Response of Liquefiable Soils

   https://doi.org/ascelibrary.org/doi/abs/10.1061/9780784480779.227  

   Manzari, M.T.; Yonten, K.Y. (July 2017, Sixth Biot Conference on Poromechanics)

   Calibration and validation of constitutive models and numerical modeling techniques used in analysis of soil liquefaction and its effects are often based on extensive comparisons with the results of element tests and centrifuge experiments. While good quality experimental data are available to understand and quantify the stress-strain-strength response of liquefiable soils in monotonic and cyclic drained/undrained element (triaxial and direct simple shear) tests, the results of these experiments are often less repeatable when the soil approaches liquefaction state and relatively large deviatoric strains suddenly develop within a few cycles of loading. The main source of these less repeatable patterns of soil behavior appears to be instability rather than the attainment of a state of material failure. The goal of this paper is to investigate the role of instability on the stress-strain response of liquefiable soils by using a critical state sand plasticity model that is enriched with an internal length scale representing the potential shear bands that may develop during monotonic or cyclic loading conditions. Through a series of numerical simulations, it is shown that the global stress-strain response measured in the element tests is a good approximation of the soil constitutive response before an unstable condition such as shear banding or liquefaction develops in the soil specimen. 

   more » « less
5. Sensitivity Analysis and Bayesian Calibration of OpenSees Models Using quoFEM

   Yi, Sr.; Satish, A.B.; Nair, A.S.; Arduino, P.; Zsarnóczay, A.; McKenna, F. (April 2023, Proceedings of the 2022 Eurasian OpenSees Days)

   The NHERI SimCenter is a nine-year research project that aims to advance the simulation of natural hazard impact on the built environment and communities. The SimCenter is developing several open-source workflow applications and an underlying scientific application framework. All applications built on this framework provide an OpenSees interface that enables users to use their existing models in advanced simulation studies, such as local and regional performance assessment, and uncertainty quantification (UQ). SimCenter applications provide researchers an opportunity to explore different extensions of their models by lowering the interdisciplinary barrier and encouraging collaboration. Among the applications, quoFEM provides access to UQ analyses with an easy-to-use, standardized interface. This work demonstrates the research enabled by quoFEM through the example of model calibration using PM4Sand, a soil constitutive model available in OpenSees. After an initial sensitivity analysis, the model is calibrated using Bayesian inference based on observations of hysteretic soil response from cyclic direct simple shear tests. The uncertainty in the model parameters is used in forward propagation to explore plausible lateral spreading scenarios due to seismic liquefaction. The results demonstrate the utility of quoFEM to the OpenSees community as a UQ-enabling tool. 

   more » « less