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Nicolás Andrés Galano, Patricio Alejandro Moreno-Casas, Jose Antonio Abell. Extending the Particle Finite Element Method for Sediment Transport Simulation. Computer Methods in Applied Mechanics and Engineering
The present work extends the capabilities of the Particle Finite Element Method (PFEM), which allows modeling of soil-fluid-structure interaction problems, to allow the modeling of sediment transport and scouring effects. This is accomplished by implementing scouring rules on an evolving scourable-interface, i.e. the interface surface between fluid and soil. The proposed method improves upon previous proposals by jointly capturing both the temporal and spatial scales of scouring evolution, as shown in the presented validation exercise, and also because its parametrization is conforms with commonplace engineering procedures for scouring prediction. The extension preserves desirable PFEM properties such as conservation of mass, mesh-size independence, and stability of the numerical solution of the PFEM equations.
[Accepted] Haoyuan Liu, Andrea Diambra, José Antonio Abell, Federico Pisanò. Memory-enhanced plasticity modelling of sand behaviour under undrained cyclic loading. Journal of Geotech. and Geoenvironmental Eng.
This work presents a critical state plasticity model for predicting the response of sands to cyclic loading. The well-known bounding surface SANISAND framework by Dafalias & Manzari (2004) is enhanced with a `memory surface' to capture micro-mechanical, fabric-related processes directly effecting cyclic sand behaviour. The resulting model, SANISAND-MS, was recently proposed by Liu et al. (2019) , and successfully applied to the simulation of drained sand ratcheting under thousands of loading cycles. Herein, novel ingredients are embedded into Liu et al. (2019) 's formulation to better capture the effects of fabric evolution history on sand stiffness and dilatancy. The new features enable remarkable accuracy in simulating undrained pore pressure build-up and cyclic mobility behaviour in medium-dense/dense sand. The performance of the upgraded SANISAND-MS is validated against experimental test results from the literature - including undrained cyclic triaxial tests at varying cyclic loading conditions and pre-cyclic consolidation histories. The proposed modelling platform will positively impact the study of relevant cyclic/dynamic problems, for instance, in the fields of earthquake and offshore geotechnics.
Patricio A. Moreno-Casas, Felipe Scott, José Delpiano, José A. Abell, Francisco Caicedo, Raúl Muñoz, and Alberto Vergara-Fernández. Mechanistic Description of Convective Gas–Liquid Mass Transfer in Biotrickling Filters Using CFD Modeling. Environmental Science & Technology 2020 54 (1), 419-426
The gas−liquid mass transfer coefficient is a key parameter to the design and operation of biotrickling filters that governs the transport rate of contaminants and oxygen from the gas phase to the liquid phase, where pollutant biodegradation occurs. Mass transfer coefficients are typically estimated via experimental procedures to produce empirical correlations, which are only valid for the bioreactor configuration and range of operational conditions under investigation. In this work, a new method for the estimation of the gas−liquid mass transfer coefficient in biotrickling filters is presented. This novel methodology couples a realistic description of the packing media (polyurethane foam without a biofilm) obtained using microtomography with computational fluid dynamics. The two-dimensional analysis reported in this study allowed capturing the mechanisms of the complex processes involved in the creeping porous air and water flow in the presence of capillary effects in biotrickling filters. Model predictions matched the experimental mass transfer coefficients (±30%) under a wide range of operational conditions.
The modelling and simulation of cyclic sand ratcheting is tackled via a plasticity model formulated withinthe well-known critical state, bounding surface SANISAND framework. For this purpose, a third locus –termed ‘memory surface’ – is cast into the constitutive formulation, so as to phenomenologically capturemicro-mechanical, fabric-related processes directly relevant to the cyclic response. The predictive capabilityof the model under numerous loading cycles (‘high-cyclic’ loading) is explored with focus on drainedloading conditions, and validated against experimental test results from the literature – including triaxial,simple shear and oedometer cyclic loading. The model proves capable of reproducing the transition fromratcheting to shakedown response, in combination with a single set of soil parameters for different initial,boundary and loading conditions. This work contributes to the analysis of soil-structure interaction underhigh-cyclic loading events, such as those induced by environmental and/or traffic loads.
José. A. Abell, Nebojša Orbović, David B. McCallen and Boris Jeremić. Earthquake Soil Structure Interaction of Nuclear Power Plants, differences in response to 3-D, 3×1-D, and 1-D excitations. Earthquake Engineering and Structural Dynamics, in print, 2018.
In soil-structure interaction modeling of systems subjected to earthquake motions, it is classically assumed that the incoming wave field, produced by an earthquake, is unidimensional and vertically propagating. This work explores the validity of this assumption by performing earthquake soil-structure interaction modeling, including explicit modeling of sources, seismic wave propagation, site, and structure. The domain reduction method is used to couple seismic (near-field) simulations with local soil-structure interaction response. The response of a generic nuclear power plant model computed using full earthquake soil-structure interaction simulations is compared with the current state-of-the-art method of deconvolving in depth the (simulated) free-field motions, recorded at the site of interest, and assuming that the earthquake wave field is spatially unidimensional. Results show that the 1-D wave-field assumption does not hold in general. It is shown that the way in which full 3-D analysis results differ from those which assume a 1-D wave field is dependent on fault-to-site geometry and motion frequency content. It is argued that this is especially important for certain classes of soil-structure systems of which nuclear power plants subjected to near-field earthquakes are an example.
Catalina Fortuño, Juan Carlos de la Llera, Charles W. Wicks, and José A. Abell - Synthetic Hybrid Broadband Seismograms Based on InSAR Coseismic Displacements. Bulletin of the Seismological Society of America published ahead of print November 18, 2014, doi:10.1785/0120130293
Conventional acceleration records do not properly account for the observed coseismic ground displacements, thus leading to an inaccurate definition of the seismic demand needed for the design of flexible (long-period) structures. Large coseismic displacements observed during the Feb 27, 2010, Maule earthquake, suggest that this effect should be included in the design of flexible structures by modifying the design ground-motions and spectra considered. Consequently, Green’s Functions are used herein to compute synthetic low-frequency seismograms that are consistent with the coseismic displacement field obtained from interferometry using synthetic aperture radar images. In this case, the coseismic displacement field was determined by interfering twenty SAR images of the ALOS-PALSAR satellite taken between 10/12/2007 and 05/28/2010. These images cover the region affected by the M w 8.8 2010, Maule earthquake. Synthetic broadband seismograms are built by superimposing the low-pass filtered synthetic low-frequency seismograms with high-frequency strong-motion data. The broadband seismograms generated are then consistent with the coseismic displacement field and the high-frequency content of the earthquake. A sensitivity analysis is performed using three different fault and slip parameters, the rupture velocity, the corner frequency, and the slip rise time. Results show that the optimal corner frequency of the low-pass filter
José A. Abell, Juan Carlos de la Llera, Charles W. Wicks - Enhancement of long period components of recorded and synthetic ground motions using InSAR. Soil Dynamics and Earthquake Engineering 01/2011; 31(5):817-829. DOI:10.1016/j.soildyn.2011.01.005
Tall buildings and flexible structures require a better characterization of long period ground motion spectra than the one provided by current seismic building codes. Motivated by that, a methodology is proposed and tested to improve recorded and synthetic ground motions which are consistent with the observed co-seismic displacement field obtained from interferometric synthetic aperture radar (InSAR) analysis of image data for the Tocopilla 2007 earthquake (Mw=7.7) in Northern Chile. A methodology is proposed to correct the observed motions such that, after double integration, they are coherent with the local value of the residual displacement. Synthetic records are generated by using a stochastic finite-fault model coupled with a long period pulse to capture the long period fling effect.It is observed that the proposed co-seismic correction yields records with more accurate long-period spectral components as compared with regular correction schemes such as acausal filtering. These signals provide an estimate for the velocity and displacement spectra, which are essential for tall-building design. Furthermore, hints are provided as to the shape of long-period spectra for seismic zones prone to large co-seismic displacements such as the Nazca-South American zone.
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Yuan Feng, José Abell, Sumeet Kumar Sinha, Han Yang, Fatemah Behbehani, Hexian Wang, Nebojša Orbović, David B McCallen and Boris Jeremić. Verification for the Real ESSI Simulator. In proceedings of Structural Mechanics in Reactor Technology (SMiRT) 24 conference, Busan, South Korea, August 20-25, 2017.
J. A. Abell, J. G. F. Crempien, and B. Jeremić - Physics-Based Scenario Modeling for Earthquake-Soil-Structure Interaction of Buildings in Proceedings of the 16th. World Conference on Earthquake Engineering, 2017.
José Antonio Abell Mena, Sumeet Kumar Sinha, Boris Jeremić - Wavelet Based Synthetic Earthquake Sources for Path and Soil Structure Interaction Modeling: Stress Testing of Nuclear Power Plants Proceedings of IAEA conference on: Best Practices in Physics-based Fault Rupture Models for Seismic Hazard Assessment of Nuclear Installations, Vienna, Austria, November 1820, 2015
Nebojša Orbović, Boris Jeremić, José Antonio Abell Mena, Chao Luo, Robert P. Kennedy and Andrei Blaihoanu - Use of Nonlinear, Time Domain Analysis for Design of NPPs in Proceedings of the Structural Mechanics in Reactor Technology (SMiRT) 2015 Conference, Manchester, August 10-14, 2015.
N.Tafazzoli, F. Pisanò, J. A. Abell M., B. Kamrani, C.-G. Jeong, B. Aldridge, R. Roche, A. Kammerer, and B. Jeremic - * ESSI Simulator Program, Current Status* . Proceedings of the 22nd. Structural Mechanics in Reactor Technology (SMiRT 22) Conference, San Francisco, California, U.S.A.
Earthquake-Soil-Structure Interaction Modeling of Nuclear Power Plants for Near-Field Events - Ph.D. Dissertation - University of California at Davis, March 2016
InSAR Compatible Ground Motions for Northern Chile - Masters Thesis - Pontificia Universidad Católica de Chile, August 2009