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Book of Abstracts BOOK OF ABSTRACTS Hosted by Vanderbilt University May 22-25, 2016 BOOK OF ABSTRACTS EMI 2016 / PMC 2016 411: 20 Year Old Real-Time Sensor and Management Systems Chung Song, University of Nebraska-Lincoln Dong D. Yoon, GS Construction Incheon International Airport in South Korea was built on an artificial island. This artificial island primarily consisted of clayey and silty hydraulic filled materials overlain by marine soft clayey soils. Due to the inherent low strength and high settlement expected from these weak soils, massive ground improvement techniques were designed. Additionally, a pilot test fill was built with several different ground improvement techniques with 965 sensors for performance monitoring, and performance was supposed to be reported on daily basis.To meet the reporting frequency requirement, an automatic data logging (called “tele-measuring” at that time) system and real time data analysis/reporting system was adapted. With this system, daily performance reporting could be made without any difficulties – it even could predict the future settlement, possible completion time of consolidation, and amount of extra fill materials needed. In addition the system could predict the impending failure of a 21 ft. high slope on a rainy day – the contractor was immediately alerted for the retrofitting work and failure was prevented.This presentation contains most components that modern Cyber Infrastructure Management System contains in an old fashioned way. But it clearly shows some insight on the capability of modern Cyber Infrastructure Management System. 149: 2D Meso-Scale Modeling of Masonry Elements Using Cohesive Elements Shenghan Zhang, Ecole Polytechnique Fédérale de Lausanne (EPFL) Seyedeh Mohadeseh Taheri Mousavi, Ecole Polytechnique Fédérale de Lausanne (EPFL) Nicolas Richart, Ecole Polytechnique Fédérale de Lausanne (EPFL) Jean-François Molinari, Ecole Polytechnique Fédérale de Lausanne (EPFL) Katrin Beyer, Ecole Polytechnique Fédérale de Lausanne (EPFL) Many stone masonry structures that were constructed in the past centuries are now counted towards the cultural heritage. The low strength and brittle behavior make these heterogeneous structures very vulnerable to various natural or man-made disasters such as earthquakes. In order to ensure their structural safety and to implement appropriate interventions, engineers need to understand the failure mechanism and to estimate the force and deformation capacity. Since it is difficult to obtain detailed material properties and simulate strong discontinuities, advanced simulation techniques have only been applied recently to masonry structures. In this paper, we simulate stones and mortar separately on a meso level and use cohesive zone modeling for simulating dynamic crack propagation. With this approach, cracks are modelled explicitly and the properties of the crack interface can be easily reflected. We apply the extrinsic cohesive zone model developed by Snozzi and Molinari, 2013. In the extrinsic method, the cohesive element will not be inserted until the stress on the corresponding element edge meets a certain criterion. The finite element analysis is developed using the open source software Akantu, newly developed by LSMS, EPFL. The available cohesive element is enhanced to consider the transfer of friction across interfaces and the added code is parallelized to make use of the high performance computing capacities of Akantu. We conduct parametric studies to investigate the influence of several variables on the force-deformation characteristics of stone masonry (e.g., strength ratio between mortar and interface, the friction coefficient). The influence of the randomness of the material properties on the masonry mechanical behavior is also examined and the effect of different assumptions with regard to the correlation of variables explored. 249: 3D Experimental Investigation of Fabric Evolution During Triaxial Compression of Granular Materials BOOK OF ABSTRACTS EMI 2016 / PMC 2016 Andrew Druckrey, University of Tennessee Khalid Alshibli, University of Tennessee Fabric of granular materials is used to describe particle-to-particle association within a mass of a granular material. It is well known that fabric has a significant influence on the behavior of granular materials. Microstructural directional data in granular materials such as branch vectors or contact normal vectors can be quantified by fabric tensors to describe fabric anisotropy. Such 3D experimental measurements have been elusive until recently. Synchrotron micro-computed tomography (SMT) imaging technique was used to acquire multiple in-situ images during triaxial compression experiments on rounded spherical glass beads and angular silica sand. Contact normal vector and branch vector fabric elements are quantified for both materials. Fabric element orientation is analyzed and fabric tensors are calculated at incremental strain levels. Internal fabric anisotropy within the two materials, defined by the normalized second invariant of the second order deviatoric fabric tensor, correlates well with the global loading of the material. The presentation will discuss the effects of particle-scale morphology on the initial fabric and fabric evolution within sheared specimens of granular materials. 242: 3D Experimental Investigation of Local Shearing in Triaxial Testing of Sand Andrew Druckrey, University of Tennessee Khalid Alshibli, University of Tennessee Strain localization into zones of intensive shearing known as shear bands has been extensively investigated in the literature. The failure mode of specimens tested under axisymmetric triaxial compression is commonly manifested through shear bands or diffuse bifurcation (bulging). However, particles may not shear along a single band during the hardening regime before the development of the specimen global failure. To investigate particle shearing during pre-peak loading stage, a thorough grain scale approach is required to determine the behavior of the granular material. 3D synchrotron micro-computed tomography (SMT) scans of sand and glass beads were acquired at multiple strains during in-situ triaxial testing. Individual particles were identified and tracked through incremental strains and particle translation was calculated. Each particle’s neighboring particles were determined, and translation fields for each of the neighboring particles were calculated. The Euclidian length differences between the particle translation vector and neighboring particles translation vectors were averaged, resulting in a translation gradient relative to the particle’s neighboring translation vectors. The translation gradient can be utilized to determine localized shearing within granular materials. Progression of local shearing into a final well defined single or multiple shear bands provides a micro-mechanics insight into mechanisms that cause failure within sheared granular materials. 41: 3D Modeling of Grain Boundaries Using a Fully-Nonlocal and High-Performance Realization of the Quasicontinuum Method Ishan Tembhekar, California Institute of Technology Dennis Kochmann, California Institute of Technology Grain boundary-dislocation interactions have been a subject of great interest for studying and predicting deformation mechanisms in polycrystalline materials. Grain boundaries are generally responsible for size effects in the effective properties of polycrystals, e.g., affecting their strength through the Hall-Petch relation or alternative plastic mechanisms of grain boundary sliding and rotation in nano-crystalline systems. For small-scale BOOK OF ABSTRACTS EMI 2016 / PMC 2016 structures where the geometric feature size is on the same order as the characteristic microstructural size, such interactions have been shown to produce more complex size effects that may change material properties significantly. Modeling grain boundaries and studying their interactions with dislocations gives us insight into the underlying mechanisms that give rise to the aforementioned size effects. Here, we investigate the interaction of dislocations with grain boundaries in aluminum and study the energy and strength of the grain boundary. Dislocations are created by nanoindentation and travel towards the grain boundary. To overcome size limitations in atomistic models, we use a fully-nonlocal quasicontinuum (QC) method which enables us to coarsen the model away from the grain boundary and to dramatically decrease the degrees of freedom in the system. Therefore, QC allows for the modeling of simulation sizes beyond the scope of traditional molecular dynamics, which are comparable to nano-crystalline structures that are studied experimentally. We use fully non-local energy-based QC with an optimal summation that minimizes force artifacts and energy errors usually associated with other existing QC frameworks. This results in an adaptive framework which reduces full atomistic resolution to those regions where it is indeed required (e.g., around the moving dislocation or near the grain boundary). We will summarize the methodology and discuss representative results for grain boundary-dislocation interactions in aluminum. 704: A 2D Fluid-Structure Interaction Method for Modeling the Performance of Resetting Semi-Passive Stiffness Dampers (RSPSD) Antonio Velazquez, Ohio University Ken Walsh, Ohio University Natural and man-made hazards, such as earthquakes, hurricanes or implosive loads, have the potential to cause large-scale forfeiture on civil infrastructure in general, often compromising
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