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Full-Text Articles in Engineering

Numerical Simulations Of The Hall–Petch Relationship In Aluminium Using Gradient-Enhanced Plasticity Model, Yooseob Song, Jaeheum Yeon, Byoungjoon Na Dec 2019

Numerical Simulations Of The Hall–Petch Relationship In Aluminium Using Gradient-Enhanced Plasticity Model, Yooseob Song, Jaeheum Yeon, Byoungjoon Na

Civil Engineering Faculty Publications and Presentations

+e Hall-Petch relation in aluminium is discussed based on the strain gradient plasticity framework. +e thermodynamically consistent gradient-enhanced flow rules for bulk and grain boundaries are developed using the concepts of thermal activation energy and dislocation interaction mechanisms. It is assumed that the thermodynamic microstresses for bulk and grain boundaries have dissipative and energetic contributions, and in turn, both dissipative and energetic material length scale parameters are existent. Accordingly, two-dimensional finite element simulations are performed to analyse characteristics of the Hall–Petch strengthening and the Hall–Petch constants. +e proposed flow rules for the grain boundary are validated using the existing experimental …


Heat Wave Intensity Duration Frequency Curve: A Multivariate Approach For Hazard And Attribution Analysis, Omid Mazdiyasni, Mojtaba Sadegh, Felicia Chiang, Amir Aghakouchak Oct 2019

Heat Wave Intensity Duration Frequency Curve: A Multivariate Approach For Hazard And Attribution Analysis, Omid Mazdiyasni, Mojtaba Sadegh, Felicia Chiang, Amir Aghakouchak

Civil Engineering Faculty Publications and Presentations

Atmospheric warming is projected to intensify heat wave events, as quantified by multiple descriptors, including intensity, duration, and frequency. While most studies investigate one feature at a time, heat wave characteristics are often interdependent and ignoring the relationships between them can lead to substantial biases in frequency (hazard) analyses. We propose a multivariate approach to construct heat wave intensity, duration, frequency (HIDF) curves, which enables the concurrent analysis of all heat wave properties. Here we show how HIDF curves can be used in various locations to quantitatively describe the likelihood of heat waves with different intensities and durations. We then …


A Physically Based Constitutive Model For Dynamic Strain Aging In Inconel 718 Alloy At A Wide Range Of Temperatures And Strain Rates, George Z. Voyiadjis, Yooseob Song Sep 2019

A Physically Based Constitutive Model For Dynamic Strain Aging In Inconel 718 Alloy At A Wide Range Of Temperatures And Strain Rates, George Z. Voyiadjis, Yooseob Song

Civil Engineering Faculty Publications and Presentations

Dynamic strain aging has a huge effect on the microstructural mechanical behavior of Inconel 718 high-performance alloy when activated. In a number of experimental researches, significant additional hardening due to the dynamic strain aging phenomenon was reported. A constitutive model without considering dynamic strain aging is insufficient to accurately predict the material behavior. In this paper, a new constitutive model for Inconel 718 high-performance alloy is proposed to capture the additional hardening, which is caused by dynamic strain aging, by means of the Weibull distribution probability density function. The derivation of the proposed constitutive relation for the dynamic strain aging-induced …


A Comparison Of Three Types Of Permeable Pavements For Urban Runoff Mitigation In The Semi-Arid South Texas, U.S.A, Taufiqul Alam, Ahmed Mahmoud, Kim D. Jones, Juan Cesar Bezares-Cruz, Javier Guerrero Sep 2019

A Comparison Of Three Types Of Permeable Pavements For Urban Runoff Mitigation In The Semi-Arid South Texas, U.S.A, Taufiqul Alam, Ahmed Mahmoud, Kim D. Jones, Juan Cesar Bezares-Cruz, Javier Guerrero

Civil Engineering Faculty Publications and Presentations

This study examines the hydrologic and environmental performance of three types of permeable pavement designs: Porous Concrete Pavement (PCP), Permeable Interlocking Concrete (PICP), and Interlocking Block Pavement with Gravel (IBPG) in the semi-arid South Texas. Outflow rate, storage, Normalized Volume Reduction (NVR), Normalized Load Reductions (NLR) of Total Suspended Solids (TSS), and Biochemical Oxygen Demand (BOD5) were compared to results obtained from adjacent traditional pavements at different regional parking lots. A notable percentage of peak flow attenuation of approximately 31–100% was observed when permeable pavements were constructed and implemented. IBPG was capable to hold runoff from rainfall depths …


Winslamm Simulation Of Hydrologic Performance Of Permeable Pavements—A Case Study In The Semi-Arid Lower Rio Grande Valley Of South Texas, United States, Taufiqul Alam, Ahmed Mahmoud, Kim D. Jones, Juan Cesar Bezares-Cruz, Javier Guerrero Sep 2019

Winslamm Simulation Of Hydrologic Performance Of Permeable Pavements—A Case Study In The Semi-Arid Lower Rio Grande Valley Of South Texas, United States, Taufiqul Alam, Ahmed Mahmoud, Kim D. Jones, Juan Cesar Bezares-Cruz, Javier Guerrero

Civil Engineering Faculty Publications and Presentations

his study used the Source Loading and Management Model for Windows (WinSLAMM) to develop a set of calibrated hydrologic models for three types of regional permeable pavements—porous concrete pavement (PCP), permeable interlocking concrete pavement (PICP), and interlocking block pavement with gravel (IBPG). The objective was to assess the hydrologic performance of permeable pavements, including the runoff depth, peak discharge, percentage increment in runoff reduction of pavements as a function of rainfall depth, development area, and base aggregate porosity, respectively. The permeable pavements were monitored over a wide range of rainfall events in the semi-arid Lower Rio Grande Valley of South …


Effects Of Epoxy Adhesive Layer Thickness On Bond Strength Of Joints In Concrete Structures, Jaeheum Yeon, Yooseob Song, Kwan Kyu Kim, Julian Kang Jul 2019

Effects Of Epoxy Adhesive Layer Thickness On Bond Strength Of Joints In Concrete Structures, Jaeheum Yeon, Yooseob Song, Kwan Kyu Kim, Julian Kang

Civil Engineering Faculty Publications and Presentations

In the construction field, adhesives are frequently used to improve adhesion between two objects. Epoxy adhesives are applied as long-term solutions, improving the bond between repair materials and existing concrete structures. Experimental investigations of the relationship between the thickness of an adhesive layer and its shear strength have been conducted by a number of industries outside of the construction sector. However, that research used metal plates as adherends when determining the shear strengths of epoxy adhesives. Therefore, this study examines epoxy adhesives’ shear strength development when applied to concrete adherends. The test results show that the thickness of the bond …


Incorporating Antecedent Soil Moisture Into Streamflow Forecasting, Abdoul Oubeidillah, Glenn Tootle, Thomas Piechota Jun 2019

Incorporating Antecedent Soil Moisture Into Streamflow Forecasting, Abdoul Oubeidillah, Glenn Tootle, Thomas Piechota

Civil Engineering Faculty Publications and Presentations

This study incorporates antecedent (preceding) soil moisture into forecasting streamflow volumes within the North Platte River Basin, Colorado/Wyoming (USA). The incorporation of antecedent soil moisture accounts for infiltration and can improve streamflow predictions. Current Natural Resource Conservation Service (NRCS) forecasting methods are replicated, and a comparison is drawn between current NRCS forecasts and proposed forecasting methods using antecedent soil moisture. Current predictors used by the NRCS in regression-based streamflow forecasting include precipitation, streamflow persistence (previous season streamflow volume) and snow water equivalent (SWE) from SNOTEL (snow telemetry) sites. Proposed methods utilize antecedent soil moisture as a predictor variable in addition …


Predicting Power-Transformer Bushings’ Seismic Vulnerability: Mounting Stiffness And Coupling, Jon Bender, Arvin Farid Jun 2019

Predicting Power-Transformer Bushings’ Seismic Vulnerability: Mounting Stiffness And Coupling, Jon Bender, Arvin Farid

Civil Engineering Faculty Publications and Presentations

Large power transformers are both expensive and vulnerable to seismic failure. Excessive amplification of earthquake loading to power transformer bushings beyond the bushings’ rated strength can occur if the system’s structural dynamics produce unpredictable and unfavorable resonance behavior. Determining the degree of vulnerability to large seismic amplifications is not straight-forward, and general design recommendations do not always resolve problems that can potentially arise. This paper considers a number of Case studies in an attempt to postulate a set of critical factors, which might facilitate better prediction of bushing amplification. Further, several additional Case studies are summarized in order to add …


Tree-Ring Reconstructions Of Streamflow For The Tennessee Valley, Sallyrose Anderson, Ross Ogle, Glenn Tootle, Abdoul Oubeidillah Apr 2019

Tree-Ring Reconstructions Of Streamflow For The Tennessee Valley, Sallyrose Anderson, Ross Ogle, Glenn Tootle, Abdoul Oubeidillah

Civil Engineering Faculty Publications and Presentations

This study reports the preliminary results from a statistical screening of tree-ring width records from the International Tree-Ring Data Bank (ITRDB), to evaluate the strength of the hydrological signal, in dendrochronological records from the Tennessee Valley. We used United States Geological Survey (USGS) streamflow data from 11 gages, within the Tennessee Valley, and regional tree-ring chronologies, to analyze the dendroclimatic potential of the region, and create seasonal flow reconstructions. Prescreening methods included correlation, date, and temporal stability analysis of predictors to ensure practical and reliable reconstructions. Seasonal correlation analysis revealed that large numbers of regional tree-ring chronologies were significantly correlated …


A Robust Decision Support Leader-Follower Framework For Design Of Contamination Warning System In Water Distribution Network, Mohammad S. Khorshidi, Mohammad Reza Nikoo, Elham Ebrahimi, Mojtaba Sadegh Mar 2019

A Robust Decision Support Leader-Follower Framework For Design Of Contamination Warning System In Water Distribution Network, Mohammad S. Khorshidi, Mohammad Reza Nikoo, Elham Ebrahimi, Mojtaba Sadegh

Civil Engineering Faculty Publications and Presentations

In recent years, several models have been proposed to inoculate Water Distribution Systems (WDS) against impacts of accidental and/or intentional compromised water quality through optimal deployment of online monitoring sensors in the network, which is referred to as Contamination Warning Systems (CWS). Translating such modeling efforts to real-world practice is, however, a challenge as different involved parties may pursue conflicting goals and modeling-based recommendations may not justify all stakeholders’ criteria. It is, hence, pivotal to develop conflict resolution methodologies to support engagement of different stakeholders in securing a safe water distribution. The decision making structure for CWS design is often …


Climate‐Induced Changes In The Risk Of Hydrological Failure Of Major Dams In California, Iman Mallakpour, Amir Aghakouchak, Mojtaba Sadegh Feb 2019

Climate‐Induced Changes In The Risk Of Hydrological Failure Of Major Dams In California, Iman Mallakpour, Amir Aghakouchak, Mojtaba Sadegh

Civil Engineering Faculty Publications and Presentations

Existing major reservoirs in California, with average age above 50 years, were built in the previous century with limited data records and flood hazard assessment. Changes in climate and land use are anticipated to alter statistical properties of inflow to these infrastructure systems and potentially increase their hydrological failure probability. Because of large socioeconomic repercussions of infrastructure incidents, revisiting dam failure risks associated with possible shifts in the streamflow regime is fundamental for societal resilience. Here we compute historical and projected flood return periods as a proxy for potential changes in the risk of hydrological failure of dams in a …


Evaluating Shallow Mixing Protocols As Application Methods For Microbial Induced Calcite Precipitation Targeting Expansive Soil Treatment, Bhaskar C. S. Chittoori, Tasria Rahman, Malcolm Burbank, Arif Ali Baig Moghal Jan 2019

Evaluating Shallow Mixing Protocols As Application Methods For Microbial Induced Calcite Precipitation Targeting Expansive Soil Treatment, Bhaskar C. S. Chittoori, Tasria Rahman, Malcolm Burbank, Arif Ali Baig Moghal

Civil Engineering Faculty Publications and Presentations

Expansive soils, also known as swell-shrink soils, undergo substantial volumetric changes due to moisture fluctuations from seasonal variations. These volumetric changes cause millions of dollars in damages annually. Microbial Induced Calcite Precipitation (MICP) is a promising soil improvement technique, which uses urease producing bacteria to precipitate calcium carbonate. In this study, a stabilization alternative for expansive soils was studied using MICP. Specifically, indigenous bacteria were stimulated by mixing enrichment and cementation solutions with expansive natural soils to precipitate calcium carbonate and make soil stronger and less expansive. This study examined three expansive soils with varying plasticity and mineralogical characteristics. Two …


Coupled Numerical Analysis Of Variations In The Capacity Of Driven Energy Piles In Clay, Arvin Farid, Daniel P. Zimmerman Jan 2019

Coupled Numerical Analysis Of Variations In The Capacity Of Driven Energy Piles In Clay, Arvin Farid, Daniel P. Zimmerman

Civil Engineering Faculty Publications and Presentations

Energy piles are an emerging alternative for the reduction of energy consumption to heat and cool buildings. Most of the research to date has focused on thermodynamic properties or axial and radial stress and strain of piles. This paper focuses on the effects of temperature fluctuation on the capacity of driven energy piles in clayey soils. Consolidation of clay surrounding driven piles affects the pile capacity (i.e., set up in clay). The heating and cooling periods of energy piles can create the excess pore-water pressure (EPWP, ue) or relax the existing one (e.g., due to pile driving or …