Engineering Commons^™

Determination Of Anisotropy Of Granular Materials And Its Relation To Liquefaction Resistance Under Cyclic Loading, Omer Faruk Capar

Civil & Environmental Engineering Theses & Dissertations

Granular materials such as sand deposits have anisotropic characteristics due to the gravitational forces during depositional process and various stress histories. These anisotropic characteristics make evaluation of liquefaction resistance of soil very complex. Since obtaining undisturbed soil specimens for laboratory tests from discrete elements like sandy soils is very laborious, the soil specimens are reconstituted in laboratory with regards to the in-situ density of soil. Reconstituting the soil changes the soil fabric or anisotropic characteristics in comparison with field conditions. Many researchers have pointed out that liquefaction resistance is highly influenced by differences in the structure of the soil (or …

Feasibility Study To Extract Iron And Chromium From Chromium Contaminated Soils, Wiwat Kamolpornwijit

Dissertations

Chromium contaminated soils, besides being recognized for toxic and hazardous hexavalent chromium, contain high iron concentrations. At some sites, concentrations of iron oxide are higher than 30%. Both iron and chromium in soils have recyclable value provided they can be either concentrated in the oxide form or separated as metal. The concentrated oxide can be used as a substitute for the iron ore. The extracted metal can also be recycled in the steel industry. The objective of this study is to study the feasibility of extracting iron and chromium from soils.

Chromium contaminated soils, can be classified into two groups, …

A Delay Model For Exclusive Right-Turn Lanes At Signalized Intersections With Uniform Arrivals And Right Turns On Red, Mohammad A. Qureshi

Doctoral Dissertations

Right turn on red (RTOR) is an established part of today’s driving patterns. However,despite several revisions of the Highway Capacity Manual (HCM), the procedures for estimating delay at signalized intersections do not adequately incorporate the effects of RTOR. The HCM currently removes RTOR from the analysis.

This dissertation has developed models of uniform delay that incorporate RTOR based on queuing theory. Queuing accumulation polygons (QAP) were developed that include RTOR. The research developed a classification system for describing any signal phasing into one of 4 classes based on the sequence of 3 red regimes and one green regime.

It was …

Formulation And Assessment Of A Customizable Procedure For Pavement Distress Index, Zongren Wang

Doctoral Dissertations

A customizable procedure for the formulation of Pavement Distress Index (PDI) based on human rating behavior is presented in this dissertation. This procedure formulates PDI as the maximum PDI value in a user-defined scale minus the Total Deduct Value (TDV), which is the sum of the product of each individual Deduct-Value (DV) and its corresponding weight. These weights, defined as a function of corresponding DV-percentages, i.e. individual DV over TDV, are identified using data simulated according to the studies by Sun and Yao (1991) and PAVER, a Pavement Management System (PMS) developed by the U. S. Army Corps of Engineers. …

Multimedia Modeling Of Organic Contaminants In The Passaic River Watershed, Lansana Coulibaly

Dissertations

A dynamic fate and transport multimedia environmental model was developed and applied to assess the release of five priority contaminants in the Passaic River Watershed, including: napthalene, toluene, trichloroethylene, 1-1-1 trichloroethane and xylene. The model uses the current releases of contaminants as well as cross-boundary advection to determine the fate and environmental distribution of these chemicals in the watershed. The model was developed using a dynamic fugacity approach in order to allow for scenario analysis such as source reductions and no-action alternatives. This modeling effort is expected to achieve a comprehensive assessment of contaminants not only in the proximity of …

Internal Forces In A Reinforced Concrete Box Culvert, Scott Mitchell Wood

Masters Theses

In 1996, a reinforced concrete box culvert with approximately 19 meters of embankment fill was instrumented with strain gages and pressure cells to determine the internal forces applied to the culvert. Strain and pressure readings were taken for a period of 3 years during and after the construction of the embankment. From a knowledge of the culvert's dimensions and material properties, the strain readings were converted to forces and bending moments. These forces were then compared to the allowable criteria from the American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Highway Bridges. A computer model of …

Computational Investigation Of Stress, Contact Conditions, And Buckling Of Thin-Walled Pipe Liners, Meihuan Zhu

Doctoral Dissertations

Thin walled polymeric liners are often used to rehabilitate deteriorated pipe lines. The host pipes into which these liners are installed are typically assumed to be structurally sound, and the liner is only expected to carry the external pressure exerted by the groundwater. This external pressure will induce creep deformation and radial deflections that may eventually result in collapse of the liner within the host pipe. The aim of this work is use computational modeling to better understand the evolution of conditions leading up to collapse so that improved liner design models can be developed. Emphasis is placed on a …

Empirical Evaluation Of The Civil Engineer Career Pyramid And Career Guidance, Travis K. Leighton

Theses and Dissertations

Air Force civil engineer officers rely on published guidance to assist in establishing their career objectives. This thesis uses empirical data to evaluate the published Air Force career guidance. The data set is comprised of complete duty histories from all active duty lieutenant colonels in the civil engineer career field. The guidance implies a career path to become a civil engineer squadron commander but provides no empirical validation. This thesis follows a rigorous procedure to objectively evaluate the Air Force guidance. The guidance is translated into 24 research questions based on its main tenets. Each duty occurrence is categorized by …

The Influence Of Outsourcing On Job Satisfaction And Turnover Intentions Of Air Force Civil Engineer Company Grade Officers, James F. Kennedy

Theses and Dissertations

A survey was distributed to 865 active duty Air Force Civil Engineer company grade officers (CGOs) assigned to locations throughout the world. The survey was designed to assess the CGOs' current job satisfaction and their intentions towards making a career out of the Air Force. Additionally, the survey measured the CGOs' perceptions of outsourcing, and how they feel that it will influence the Civil Engineer career field. Relationships were evaluated between the perceptions of outsourcing and job satisfaction, and between job satisfaction and turnover intentions. Overall, Civil Engineer CGOs reported a slightly positive level of satisfaction and a negative perception …

Performance-Based Seismic Engineering Of Low And Medium-Rise Steel Frames, Saeid Rashidi

Dissertations

The performance level of low and medium-rise steel frames designed according to the common force/strength approach of the UBC or NEHRP is determined. Several combinations of soil profile type, lateral-force-resisting system, and frame-member proportioning are included in the designs.

To evaluate the expected damage, nonlinear models of the designed frames are subjected to a number of actual and simulated ground motion accelerograms and appropriate structural response parameters such as, interstory drift, ductility demand, and dissipated hysteretic energy are obtained. In addition, a modified form of Park-Ang damage index is calculated for moment-resisting frames. The seismic performance of the steel frames …

The Influence Of High Performance Matrices On Fracture Behavior Of Concrete, Pusit Lertwattanaruk

Dissertations

Modification of cement matrices by the addition of micro particle pozzolanic materials such as silica fume and fly ash is known to improve the strength of concrete, but its contributions to fracture behavior remains unclear. In this study, the influence of replacing cement by silica fume and fly ash on the cement matrix-coarse aggregate interfacial bond, compressive stress-strain behavior and fracture behavior of concrete is investigated.

While the linear elastic fracture mechanics (LEFM) concept is not appropriate for concrete, a nonlinear fracture model based on the load vs. load-line deflection and the load vs. crack-mouthopening displacement (CMOD) responses of the …

Utilization Of Municipal Solid Waste Incinerator Fly Ash In Cement Mortars, Manaskorn Rachakornkij

Dissertations

Disposal of municipal solid waste has become a major problem in many countries around the world. With the benefits of substantial weight and volume reduction and potential energy recovery, incineration has become a promising municipal solid waste (MSW) management option. Despite the fact that incineration reduces volume and mass of the wastes by as much as 80%, there are still residues to be properly managed. This research is aimed at evaluating the potential of different types of MSWI fly ash from an incineration facility to be used in cement mortars by using existing standard test methods for cement and coal …

Finite Fraction Method For Tracking Desinfection By-Product Precursors In Water Treatment, Doanh Van

Dissertations

Dissolved Organic Matter (DOM) has been the subject of recent regulatory activities and agenda. Among them are the Infonnation Collection Rule (ICR), the Disinfectants/Disinfection By-Product Rule (D/DBPR) and the Interim Enhanced Surface Water Treatment Rule (ESWTR). Both the latter two have provisions to limit the formation of disinfection by-products (DBP) by controlling reactivity and removal of DOM or both. Brief regulatory review of these rules was given.

Although the topic of DBP formation potential and DBP precursor removal have been studied by many researchers since Rooks (1974), the efficacy of methods that have been developed to date has been handicapped …

Post-Cracking Tensile Properties Of Advanced Cementitious Materials And Ductility Of High Performance Concrete Beams, Wonsiri Punurai

Theses

In present direct tension tests, the complete stress-deformation curves, the resulting energy dissipated by damage, and the fracture energy of different types of cementitious composites, namely plain concrete, high strength concrete, normal fibrous concrete, high strength fibrous concrete, are studied and a ductility factor is calculated. It has been found that with the increasing strength of concrete due to the addition of the pozzoians such as silica fume and fly ash and when changing from normal strength to high strength, concrete ductility decreases. However, when fibers are combined with these matrices, concrete ductility increases. It is because of ductile steel …

Improved Regression-Based Streamflow Forecasting Considering Large-Scale Climate Variability, Austin R. Fisher

Dissertations and Theses

The Natural Resources Conservation Service (NRCS) produces water supply forecasts for most of the streams in the western United States. The NRCS produces forecasts starting in January, when snow course measurements of snow water equivalent were available. Although the seasonal streamflow volume forecasts made by the NRCS are useful, many water supply managers need information at the beginning of the water year in October and would like to see forecasts in the form of a monthly hydrograph.

An investigation into the effect of decadal scale variability, as reflected by the Pacific Decadal Oscillation (PDO), show important relationships that may be …