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Articles 1 - 19 of 19
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Simulation Of Fracture Of Concrete Using Micropolar Peridynamics, Asadollahi Aziz
Simulation Of Fracture Of Concrete Using Micropolar Peridynamics, Asadollahi Aziz
Civil Engineering ETDs
The main goal of the thesis is to develop a constitutive damage model for simulating tensile fracture of concrete using the micropolar peridynamics model. Micropolar peridynamics was proposed by Gerstle in 2007 as a generalization to the bond based peridynamics method introduced by Silling in 2000, which was only capable of handling materials with specific Poissons ratios. Inspired by the bilinear cohesive model in the cohesive crack approach, a new constitutive damage model is proposed to simulate the tensile fracture of a normal-strength concrete. Laboratory experimental data for crack mouth opening displacement vs. load of notched beams, obtained by Chapman …
Synthesis And Multi-Scale Characterization Of Calcium Silicate Hydrate At Multiple Cao/Sio2 Mixture Ratios, Michelle Begaye
Synthesis And Multi-Scale Characterization Of Calcium Silicate Hydrate At Multiple Cao/Sio2 Mixture Ratios, Michelle Begaye
Civil Engineering ETDs
Calcium Silicate Hydrate (C-S-H) is the primary binding agent that is responsible for setting and hardening, strength, dimensional stability, and durability of Portland cement paste. Although Portland cement hydration produces C-S-H, Calcium hydroxide (CH), ettringite, and other hydration products are also acquired from this process and make it difficult to characterize C-S-H exclusively. C-S-H was first synthesized by mixing calcium oxide (CaO), created by calcining calcium carbonate (CaCO3) that was heated to 950 \xbaC for 24 hours with fumed silica (SiO2) and deionized water (H2O) under nitrogen which produced the synthetic gel-like C-S-H slurry. This composition mixture of synthetic C-S-H …
Community Analysis Of A Unique Full-Scale Wastewater Treatment Plant As Revealed By 454-Pyrosequencing, Meghan Preut
Community Analysis Of A Unique Full-Scale Wastewater Treatment Plant As Revealed By 454-Pyrosequencing, Meghan Preut
Civil Engineering ETDs
Activated sludge is one of the most commonly applied biological treatment processes for wastewater treatment. The microorganisms grown in activated sludge systems are responsible for the removal and transformation of wastewater contaminants. These bacterial populations are sensitive to wastewater characteristics, plant design and operational parameters. Because the effectiveness of activated sludge relies on microbial activity, a better understanding of the microbial communities and how they respond to constraints may be useful for improving plant performance. Environmental conditions in the activated sludge process are complex and the identification and classification of the communities present has proven a challenge for engineers as …
Soil Moisture Measurements And Modeling At A Geomorphically Reclaimed Coal Mine In New Mexico, Shahedur Rahman
Soil Moisture Measurements And Modeling At A Geomorphically Reclaimed Coal Mine In New Mexico, Shahedur Rahman
Civil Engineering ETDs
Geomorphic reclamation is a relatively new technique in which landforms are built to be similar to those that eventually form in nature given the particular conditions of a location, making them self-sustaining and functional. The near surface water balance will have a large impact on the establishment and health of vegetation which in turn is important for maintaining a stable landform. This study developed a one-dimensional water balance model for a geomorphically reclaimed site and used the model to investigate seed germination and plant survival for a range of slope aspects and climate conditions. Disturbed and undisturbed samples of reclaimed …
The State-Based Peridynamic Lattice Model, Raybea Richardson
The State-Based Peridynamic Lattice Model, Raybea Richardson
Civil Engineering ETDs
The reigning material model of today is continuum mechanics. Continuum mechanics assumes that a material is continuous and can be represented by mathematical functions. This is an unreasonable assumption for concrete due in part to the fact that concrete cracks and the continuum mechanics model cannot directly handle fracture. In response to some of the limitations of continuum mechanics, Silling proposed a new method called peridynamics. Peridynamics assumes that a material is made up of particles which interact with each other via forces. In this thesis we introduce the state-based peridynamic lattice model (SPLM) and describe its fundamental assumptions. SPLM …
Structural Scaling Metrics For Tensioned-Blanket Space Systems, Jeremy Banik
Structural Scaling Metrics For Tensioned-Blanket Space Systems, Jeremy Banik
Civil Engineering ETDs
Structural metrics have been used for nearly a century to provide designers with simple, rational tools for comparing the mass performance of aircraft and spacecraft platforms. Large space structures designers and evaluators rely on metrics to compare boom, telescope, and long antenna architectures. In this work, scaling metrics are established for rectangular flexible blanket solar array structural architectures. The approach takes advantage of the fact that an ideal solar array structure is a system of coupled beam and tensioned blanket components rather than the typical simplifying approach of considering only one beam with a distributed mass as the blanket. A …
Managing Complex Water Resource Systems For Ecological Integrity: Evaluating Tradeoffs And Uncertainty, Ryan Morrison
Managing Complex Water Resource Systems For Ecological Integrity: Evaluating Tradeoffs And Uncertainty, Ryan Morrison
Civil Engineering ETDs
Water resource systems often contain numerous components that are intertwined or contradictory, such as power production, water delivery, recreation, and environmental needs. This complexity makes it difficult to holistically assess management alternatives. In addition, hydroclimatic and ecological uncertainties complicate efforts to evaluate the impacts of management scenarios. We need new tools that are able to inform managers and researchers of the tradeoffs or consequences associated with flow alternatives, while also explicitly incorporating sources of uncertainty. My research addresses this limitation using two modeling approaches: stochastic system dynamics modeling and Bayesian network modeling. Specifically, the objectives of my research were 1) …
On Dynamic Modulus Of Asphalt Concrete For Moisture Damage, Mekdim Weldegiorgis
On Dynamic Modulus Of Asphalt Concrete For Moisture Damage, Mekdim Weldegiorgis
Civil Engineering ETDs
Dynamic modulus (E*) test has gained substantial acceptance in recent years for evaluating Hot Mix Asphalt (HMA) rutting and fatigue cracking performances. Indeed, the recently developed Mechanistic Empirical Pavement Design Guide (MEPDG) uses E* data for stress and strain calculation, and E*-based models for prediction fatigue and rutting performances of a HMA pavement. Unfortunately, neither HMA mix design method nor the MEPDG uses E* value to evaluate moisture damage characteristics of HMA pavements. In fact, moisture damage is a very complex problem, and there exists no models for inclusion in the MEPDG for predicting moisture damage performance of HMA pavements. …
Impacts Of Diurnally Exposed Slime Layer Hydrogen Sulfide Concentrations In Sewer Atmosphere, Mark Holstad
Impacts Of Diurnally Exposed Slime Layer Hydrogen Sulfide Concentrations In Sewer Atmosphere, Mark Holstad
Civil Engineering ETDs
Hydrogen sulfide (H2S) is a major issue in wastewater collection systems. H2S can cause rapid damage to wastewater infrastructure, affects the publics quality of life through odor issues and is a safety concern for sewer workers. Relatively recent development and introduction of H2S data loggers has shown that H2S concentrations in the sewer headspace demonstrate a diurnal pattern that is not explained by current models. Odor complaints and toxicity are primarily a result of the peak concentration levels and may be more accurately predicted through a better understanding of the diurnal H2S concentration patterns. Biological slime layer grows in the …
A New Cfrp-Uhpc System For Strengthening Reinforced Concrete T-Beams, Moneeb Genedy
A New Cfrp-Uhpc System For Strengthening Reinforced Concrete T-Beams, Moneeb Genedy
Civil Engineering ETDs
Since Fiber Reinforced Polymer (FRP) was introduced to the construction field, strengthening of reinforced concrete beams using FRP laminates became a common repair and retrofit technique. Traditionally, Reinforced Concrete (RC) beams are strengthened by adhering FRP laminates to the tension side of the beam to work as an additional tensile reinforcement. Although this technique has been proven as an efficient strengthening technique, in many cases reaching the tension side of the beam is challenging due to the existing of ducts, pipes or cables underneath the beam in buildings. This challenge is magnified in bridges crossing water canals or major highways …
Water Resources Impacts Of Uranium Mining In The San Juan Basin, New Mexico, Kent Steinhaus
Water Resources Impacts Of Uranium Mining In The San Juan Basin, New Mexico, Kent Steinhaus
Civil Engineering ETDs
The objective of this research was to improve understanding of the groundwater impacts of uranium mining in the San Juan Basin by estimating the volumetric amount of water removed from the underlying Westwater Canyon member aquifer. This was achieved by modeling a conceptual mine that is based on the physical characteristics present near the proposed Roca Honda Mine near Grants, New Mexico. An analysis of the uncertainty of the physical, situational, and model parameters and their associated sensitivities was conducted so that an understanding of potential groundwater withdrawals for uranium mining could be gathered. Uranium mining in the San Juan …
Searching For The Factor Of Safety: A Study Of Wood Roof System Capacity As It Applies To Solar Photovoltaic Installation, Alfred Sanchez Iii
Searching For The Factor Of Safety: A Study Of Wood Roof System Capacity As It Applies To Solar Photovoltaic Installation, Alfred Sanchez Iii
Civil Engineering ETDs
The recent drive to install residential installation of photovoltaic roof systems has generated the need to re-examine the structural capacity of residential structures. Currently, a perspective exists that residential wood roofs may not be able to carry the additional load of a photovoltaic (PV) array. This research seeks to address how the addition of PV installations can affect the structural capacity of residential wood roof systems and to investigate the current methods in which roof systems are assigned their working strengths. With the goal of finding ultimate capacities of wood roof systems, empirical tests were conducted in a laboratory setting …
New Generation Polymer Concrete Incorporating Carbon Nanotubes, Sherif Daghash
New Generation Polymer Concrete Incorporating Carbon Nanotubes, Sherif Daghash
Civil Engineering ETDs
Polymer Concrete (PC) is one of three types of polymers in concrete that was introduced in the 1950s and has had many successful civil engineering applications. PC is recognized in the industry as a mix of aggregate and polymer resin with no Portland cement. PC has been favoured over conventional Portland cement concrete when special characteristics such as low permeability, high adhesion, and/or high durability for service in aggressive (e.g. chemical) environments are required. In this research, a new generation of PC incorporating Multi-Walled Carbon Nano-Tubes (MWCNTs) was produced and its mechanical properties were investigated. Four mixes of PC with …
Permeability And Moisture Damage Characteristics Of Asphalt Pavements, Mohiuddin Ahmad
Permeability And Moisture Damage Characteristics Of Asphalt Pavements, Mohiuddin Ahmad
Civil Engineering ETDs
In the past, numerous studies have been conducted on the topics of moisture damage and permeability, but very few studies have correlated permeability with moisture damage in Asphalt Concrete (AC). This study evaluates whether such a relation exists or not. In addition, correlations of permeability with AC mix volumetrics and pores are evaluated. Also, correlation of laboratory permeability with field permeability is examined. In this study, a field survey is conducted to identify a set of eight pavements (bad) that are known to suffer from moisture damage and a set of eight pavements (good) that do not exhibit moisture damage. …
Assessment Of Antistripping Agents On Adhesion Of Damaged Asphalt By Neural Network, Sanjida Ahsan
Assessment Of Antistripping Agents On Adhesion Of Damaged Asphalt By Neural Network, Sanjida Ahsan
Civil Engineering ETDs
In this study, Neural Network (NN) model is developed to quantify nano-level adhesion force of moisture damaged asphalt binder using Atomic Force Microscopy (AFM) test data. AFM data contains five point force-distance values determined for some specific asphalt chemical functional groups. Asphalt binder samples contain different types and percentages of polymer modifiers and antistripping agents (ASA). Due to complex and nonlinear interaction between the asphalt properties and adhesion force of asphalt, it is difficult to assess the effects of asphalt binder properties on the adhesion forces using laboratory AFM testing. NN has the ability to recognize and trace the complex …
Material Characteristics Of Hot Mix Asphalt And Binder Using Freeze-Thaw Conditioning, Ghazanfar Barlas
Material Characteristics Of Hot Mix Asphalt And Binder Using Freeze-Thaw Conditioning, Ghazanfar Barlas
Civil Engineering ETDs
Depending on the region, in a single year, the pavement undergoes many cycles of freezing and thawing. Freeze-thaw, as well as traffic loading, are important parameters in the study of damage in asphalt pavement. In areas of wide ranging temperatures, pavements are susceptible due to thermal cracking. This study investigates the effect of freeze-thaw on fatigue life and material characteristics of Hot Mix Asphalt (HMA) and binder. Since, temperature is variable throughout the year, a constant temperature should not be assumed when finding the fatigue life and material characteristics of HMA. To evaluate the damage, flexure test is conducted to …
Evaluation Of Moisture, Suction Effects And Durability Performance Of Lime Stabilized Clayey Subgrade Soils, Md Tahmidur Rahman
Evaluation Of Moisture, Suction Effects And Durability Performance Of Lime Stabilized Clayey Subgrade Soils, Md Tahmidur Rahman
Civil Engineering ETDs
Resilient modulus (MR) of soils is well-accepted and essential parameter for structural design of flexible pavements using the Mechanistic Empirical Pavement Design Guide (MEPDG). A comprehensive laboratory study is undertaken to evaluate the moisture, suction effects and durability performance on resilient modulus (MR) and unconfined compressive strength (UCS) of lime treated clayey subgrade soils. Two subgrade soils: the AASHTO class A-6 and A-7-6 are collected from US 491 road site in New Mexico. Cylindrical soil specimens are prepared according to NCHRP 1-28A at three lime percentages: 0%, 5% and 7% which are selected based on pH test. MR tests on …
Jemez River Case Study: Utilizing A Froude Number Similitude Physical Model, 1-D Mobile Bed Numerical Model, And A 2-D Fixed Bed Numerical Model For Weir Design Insight, Emile Kareem Saint-Lot
Jemez River Case Study: Utilizing A Froude Number Similitude Physical Model, 1-D Mobile Bed Numerical Model, And A 2-D Fixed Bed Numerical Model For Weir Design Insight, Emile Kareem Saint-Lot
Civil Engineering ETDs
Physical and numerical models have been widely used to describe flooding patterns and to gain further understanding of river hydraulics around complex structures. Located on the Jemez River in New Mexico, the Jemez Weir stops the upstream progression of stream degradation and supports healthy upstream riparian vegetation. Localized bed scour began to occur just downstream of the Jemez Weir following construction. The United States Army Corps of Engineers (USACE) built the structure in 2003 and developed a HEC-RAS model in 2010 to re-evaluate the long term bed degradation downstream of the weir to assess structure stability. Additionally, the USACE estimated …
Modeling Moisture-Induced Damage In Asphalt Concrete, Mohammad Hossain
Modeling Moisture-Induced Damage In Asphalt Concrete, Mohammad Hossain
Civil Engineering ETDs
Moisture damage in Asphalt Concrete (AC) is not new but an unsolved problem. For decades laboratory studies have been conducted on both loose and compacted mix to understand the effects of moisture on the AC damage. Adhesive and cohesive damages are the two major types of damages occur inside the AC. Adhesive damage is a separation between aggregate and coated mastic or matrix materials and cohesive damage is the degradation of strength of matrix materials within the AC samples. In this study, Finite Element Method (FEM) modeling technique is used to identify initiation and progression of adhesive and cohesive damage. …