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Author Antico, F.C.; De la Varga, I.; Esmaeeli, H.S.; Nantung, T.E.; Zavattieri, P.D.; Weiss, W.J. pdf  doi
openurl 
  Title Using accelerated pavement testing to examine traffic opening criteria for concrete pavements Type
  Year 2015 Publication Construction And Building Materials Abbreviated Journal Constr. Build. Mater.  
  Volume 96 Issue Pages 86-95  
  Keywords Early age-cracking; Opening to traffic; Accelerated pavement testing; Modeling; Finite element  
  Abstract The risk of cracking in a concrete pavement that is opened to traffic at early ages is related to the maximum tensile stress sigma(I), that develops in the pavement and its relationship to the measured, age dependent, flexural strength of a beam,f(r). The stress that develops in the pavement is due to several factors including traffic loading and restrained volume change caused by thermal or hygral variations. The stress that develops is also dependent on the time-dependent mechanical properties, pavement thickness, and subgrade stiffness. There is a strong incentive to open many pavements to traffic as early as possible to allow construction traffic or traffic from the traveling public to use the pavement. However, if the pavement is opened to traffic too early, cracking may occur that may compromise the service life of the pavement. The purpose of this paper is two-fold: (1) to examine the current opening strength requirements for concrete pavements (typically a flexural strength from beams, f(r)) and (2) to propose a criterion based on the time-dependent changes of sigma(I)/f(r), which accounts for pavement thickness and subgrade stiffness without adding unnecessary risk for premature cracking. An accelerated pavement testing (APT) facility was used to test concrete pavements that are opened to traffic at an early age to provide data that can be compared with an analytical model to determine the effective sigma(I)/f(r), based on the relevant features of the concrete pavement, the subgrade, and the traffic load. It is anticipated that this type of opening criteria can help the decision makers in two ways: (1) it can open pavement sections earlier thereby reducing construction time and (2) it may help to minimize the use of materials with overly accelerated strength gain that are suspected to be more susceptible to develop damage at early ages than materials that gain strength more slowly. (C) 2015 Elsevier Ltd. All rights reserved.  
  Address [Antico, F. C.; De la Varga, I.; Esmaeeli, H. S.; Zavattieri, P. D.; Weiss, W. J.] Purdue Univ, Lyles Sch Civil Engn, W Lafayette, IN 47907 USA, Email: zavattie@purdue.edu;  
  Corporate Author Thesis  
  Publisher Elsevier Sci Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0950-0618 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000361402700010 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 750  
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Author Aylwin, R.; Jerez-Hanckes, C.; Schwab, C.; Zech, J. doi  openurl
  Title Domain Uncertainty Quantification in Computational Electromagnetics Type
  Year 2020 Publication Siam-Asa Journal On Uncertainty Quantification Abbreviated Journal SIAM-ASA J. Uncertain. Quantif.  
  Volume 8 Issue 1 Pages 301-341  
  Keywords computational electromagnetics; uncertainty quantification; finite elements; shape holomorphy; sparse grid quadrature; Bayesian inverse problems  
  Abstract We study the numerical approximation of time-harmonic, electromagnetic fields inside a lossy cavity of uncertain geometry. Key assumptions are a possibly high-dimensional parametrization of the uncertain geometry along with a suitable transformation to a fixed, nominal domain. This uncertainty parametrization results in families of countably parametric, Maxwell-like cavity problems that are posed in a single domain, with inhomogeneous coefficients that possess finite, possibly low spatial regularity, but exhibit holomorphic parametric dependence in the differential operator. Our computational scheme is composed of a sparse grid interpolation in the high-dimensional parameter domain and an Hcurl -conforming edge element discretization of the parametric problem in the nominal domain. As a stepping-stone in the analysis, we derive a novel Strang-type lemma for Maxwell-like problems in the nominal domain, which is of independent interest. Moreover, we accommodate arbitrary small Sobolev regularity of the electric field and also cover uncertain isotropic constitutive or material laws. The shape holomorphy and edge-element consistency error analysis for the nominal problem are shown to imply convergence rates for multilevel Monte Carlo and for quasi-Monte Carlo integration, as well as sparse grid approximations, in uncertainty quantification for computational electromagnetics. They also imply expression rate estimates for deep ReLU networks of shape-to-solution maps in this setting. Finally, our computational experiments confirm the presented theoretical results.  
  Address [Aylwin, Ruben] Pontificia Univ Catolica Chile, Sch Engn, Santiago 7820436, Chile, Email: rdaylwin@uc.cl;  
  Corporate Author Thesis  
  Publisher Siam Publications Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2166-2525 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000551383300011 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 1207  
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Author Beltran, J.F.; Nunez, E.; Nunez, F.; Silva, I.; Bravo, T.; Moffat, R. pdf  doi
openurl 
  Title Static response of asymmetrically damaged metallic strands: Experimental and numerical approach Type
  Year 2018 Publication Construction And Building Materials Abbreviated Journal Constr. Build. Mater.  
  Volume 192 Issue Pages 538-554  
  Keywords Asymmetric damaged strands; Surface damage; Numerical model; Finite element simulation; Experimental test; Static capacity curve  
  Abstract In this study, the effect of the presence of broken wires (damage) asymmetrically distributed on metallic strands surfaces on their static response is assessed. To this end, a general mechanical model for multi layered strands is presented, in which damaged strands are treated as a 1D nonlinear beam under uncoupled biaxial bending and axial load (NLBM). The NLBM is validated by comparisons with the results obtained from an experimental program especially designed for studying the effect of surface damage distribution on strands response and 3D nonlinear finite element simulations. Analyses are carried out on two strand constructions: 1 x 7 and 1 x 19, in which the damage levels and strand diameters vary from 5% to 40% and from 3.5 mm to 22.2 mm, respectively. Results indicate that the NLBM accurate predicts the static response (residual strength, stiffness, axial strain field, and deformed configuration) of the asymmetrically damaged strands, achieving good computational efficiency and numerical robustness. (C) 2018 Elsevier Ltd. All rights reserved.  
  Address [Felipe Beltran, Juan] Univ Chile, Dept Civil Engn, Blanco Encalada 2002 Of 440, Santiago, Chile, Email: jbeltran@ing.uchile.cl;  
  Corporate Author Thesis  
  Publisher Elsevier Sci Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0950-0618 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000453494600046 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 953  
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Author Fuenzalida, C.; Jerez-Hanckes, C.; McClarren, R.G. doi  openurl
  Title Uncertainty Quantification For Multigroup Diffusion Equations Using Sparse Tensor Approximations Type
  Year 2019 Publication Siam Journal On Scientific Computing Abbreviated Journal SIAM J. Sci. Comput.  
  Volume 41 Issue 3 Pages B545-B575  
  Keywords multigroup diffusion equation; uncertainty quantification; sparse tensor approximation; finite element method  
  Abstract We develop a novel method to compute first and second order statistical moments of the neutron kinetic density inside a nuclear system by solving the energy-dependent neutron diffusion equation. Randomness comes from the lack of precise knowledge of external sources as well as of the interaction parameters, known as cross sections. Thus, the density is itself a random variable. As Monte Carlo simulations entail intense computational work, we are interested in deterministic approaches to quantify uncertainties. By assuming as given the first and second statistical moments of the excitation terms, a sparse tensor finite element approximation of the first two statistical moments of the dependent variables for each energy group can be efficiently computed in one run. Numerical experiments provided validate our derived convergence rates and point to further research avenues.  
  Address [Fuenzalida, Consuelo] Pontificia Univ Catolica Chile, Sch Engn, Santiago, Chile, Email: mcfuenzalida@uc.cl;  
  Corporate Author Thesis  
  Publisher Siam Publications Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1064-8275 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000473033300033 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 1023  
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Author Markou, G.; Genco, F. pdf  doi
openurl 
  Title Seismic assessment of small modular reactors: NuScale case study for the 8.8 Mw earthquake in Chile Type
  Year 2019 Publication Nuclear Engineering And Design Abbreviated Journal Nucl. Eng. Des.  
  Volume 342 Issue Pages 176-204  
  Keywords Small Modular Reactors; Chile 2050 energy policy; 3D Detailed Finite Element Modeling; Seismic resistance; Soil-Structure Interaction; Reinforced concrete  
  Abstract Reducing greenhouse gas emissions and improving energy production sustainability is a paramount of Chile's 2050 energy policy. This though, is difficult to achieve without some degree of nuclear power involvement, given that the geography of the country consists of many areas that are practically off-grid, whereas cannot be developed and financially exploited due to the lack of basic commodities such as water and electricity. Recently small modular reactors (SMRs) have gained lots of attention by both researchers and world policy makers for their promised capabilities of enhanced safety systems, affordable costs and competitive scalability. SMRs can be located in remote areas and at this time are being actively developed in Argentina, USA, Brazil, Russia, China, South Korea, Japan, India and South Africa. Chile's 2010 earthquake and Fukushima's 2011 nuclear disaster have increased significantly both the population's fear and opposition to Nuclear Power Energy for the possible consequences of radiation on the lives of people. This paper aims to study the seismic resistance of a typical nuclear structure, being at time proposed in Small Modular Reactors, by using earthquake conditions typically seen in Chile. Since many designs are under study, a NuScale reactor from USA is analyzed under these extreme loading conditions. The major advantages of the NuScale reactor are in the power scalability (it can go from 1 to 12 reactor cores producing from 60 to 720 MWe), limited nuclear fuel concentration, modules allocated below grade and high strength steel containments fully immersed in water. The cooling effect beyond Design Basis Accident is ensured indefinitely, which induces a significant safety factor in the case of an accident. For the purpose of this study a detailed 3D detailed structural model was developed, reproducing the NuScale reactor's reinforced concrete framing system, where nonlinear analyses was performed to assess the overall mechanical response of the structure. The framing system has been tested under high seismic excitations typically seen in Chile (Mw > 8.0), showing high resistance and capability to cope with the developed forces due to its design. Based on a Soil-Structure Interaction analysis, it was also found that the NuScale framing system manages to maintain a low-stress level at the interaction surface between the foundation and the soil, where the structural system was found to be able to withstand significant earthquake loads. Finally, further investigation is deemed necessary in order to study the potential damages of the structure in the case of other hazards such as tsunami events, blast loads, etc.  
  Address [Markou, George] Univ Pretoria, Dept Civil Engn, Pretoria, South Africa, Email: george.markou@up.ac.za;  
  Corporate Author Thesis  
  Publisher Elsevier Science Sa Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0029-5493 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000454924700016 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 968  
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