Civil and Environmental Engineering Commons^™

Sparse Equation-Eigen Solvers For Symmetric/Unsymmetric Positive-Negative-Indefinite Matrices With Finite Element And Linear Programming Applications, Hakakizumwami Birali Runesha

Civil & Environmental Engineering Theses & Dissertations

Vectorized sparse solvers for direct solutions of positive-negative-indefinite symmetric systems of linear equations and eigen-equations are developed. Sparse storage schemes, re-ordering, symbolic factorization and numerical factorization algorithms are discussed. Loop unrolling techniques are also incorporated in the coding to enhance the vector speed. In the indefinite solver, which employs various pivoting strategies, a simple rotation matrix is introduced to simplify the computer implementation. Efficient usage of the incore memory is accomplished by the proposed "restart memory management" schemes. A sparse version of the Interior Point Method, IPM, has also been implemented that incorporates the developed indefinite sparse solver for linear …

Evaluation Of Toxicity, Bioavailability And Speciation Of Lead, Zinc And Cadmium In Mine/Mill Wastewaters, Mujde Erten-Unal, Bobby G. Wixson, Nord Gale, Jerry L. Pitt

Civil & Environmental Engineering Faculty Publications

The toxicity of common compounds of lead, cadmium and zinc was evaluated in waters similar to that found in the world's largest lead producing area in Missouri. Static, acute toxicity tests were performed using fathead minnows (Pimephales promelas) and water fleas (Daphnia magna) respectively. Test organisms were subjected to varying amounts of sulfide, carbonate, chloride and sulfate salts of lead, zinc and cadmium mixed in hard, alkaline waters typical to this region. Median lethal concentrations were calculated using nominal versus measured metal concentrations. Measured metal concentrations included four different metal fractionation (extraction/filtration) techniques at different pH …

Flexural Behavior Of Thermoplastic Beams With And Without Frp Reinforcement, Hilmi Coskun

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the results of an experimental and theoretical study of the flexural behavior of thermoplastic beams with and without fiber-reinforced plastic (FRP) rebars. Tests are conducted on commercially available thermoplastic beams known as Seatimber. The normal stress-strain relations of both the thermoplastic material and FRP rebars are obtained in tension and compression experimentally. These mechanical property curves are then used as part of the input for developing the theoretical moment-curvature relations using an iterative equilibrium procedure. The moment-curvature relations are in turn used for predicting the beam load-deflection curves via the central finite-difference procedure. Behavior predictions are made …

The Detoxification Of Petroleum Contaminated Coastal Plain Sandy Soil Using An Amended Vermicomposting Approach, John Charles Kraemer

Health Services Research Dissertations

This study explores the feasibility of utilizing an amended vermicomposting treatment approach for detoxifying petroleum hydrocarbon contaminated sandy soil. The bench-scale testing of gasoline and diesel contaminated soil using three test soil vessels and one control soil vessel was performed in a laboratory setting for a six week time period. The control soil received no treatment other than distilled water to maintain soil moisture. Treatment 1 consisted of direct application of liquid municipal biologic sludge on a weekly basis. Treatment 2 consisted of the addition of 30 Eisenia foetida earthworms and distilled water. Treatment 3 consisted of direct application of …

Specification And Verification Of Generic Cell Rate Algorithms In Pvs, Huseyin Ozgungor

Electrical & Computer Engineering Theses & Dissertations

Formal verification methods have been considered as a powerful complementary approach to define standards and to prove correctness of the systems. In this work, formal specification of Generic Cell Rate Algorithms are defined and proved. The specification process enables standardization for constructing Generic Cell Rate Algorithms. Standardization is an important process in the Asynchronous Transfer Mode (ATM) networks. By employing formal methods, the necessary standards could be constructed to allow different algorithms to be employed which still meet system requirements. Those system requirements are quantified in the Quality of Service (QOS).

Congestion management is a vital concept for networks in …

The Study Of Wave-Blocking And Current Effects On Nonlinear Interactions Of Shallow-Water Waves Using Advanced Boussinesq Models, Qin Chen

Civil & Environmental Engineering Theses & Dissertations

The first part of this work focuses on the derivation of enhanced Boussinesq-type equations for the combined motion of waves and currents in shallow water areas.

The strategy proposed in this work is to couple two known methods which are the sponge layer concept suitable for short waves and Sommerfeld radiation condition for currents. This coupling method provides satisfactory non-reflective boundaries for the simulation of fully coupled wave/current motion as demonstrated by the numerical experiments. We verify the model against the well known solutions based on the existing theories and good agreement has been observed. The numerical results confirm the …

A Sociotechnical Systems Analysis Of The Approval Process For A Complex Public Works Proposal, James C. Pyne

Engineering Management & Systems Engineering Theses & Dissertations

This research applied sociotechnical systems theory to explore the process used by two elected bodies to decide upon adoption of a complex technical engineering proposal. The research used a modified sociotechnical systems conceptual framework that was developed by Pava (1983) for application to non-traditional work settings. Pava applied the conceptual framework to what he termed non-routine office work which is characterized by non-linear conversion flow, multiple, concurrent conversion processes and vocational separatism (Pava, 1983).

The research was designed as a multiple case study of two town councils each undertaking a decision process to approve or reject a public works proposal …

Characterization Of Rainfall Runoff Quality From A Shipyard Drydock, Peter Pommerenk

Civil & Environmental Engineering Theses & Dissertations

Water quality and hydrological data were collected during seventeen rain events and additional data was obtained from laboratory experiments to characterize the quality of stormwater runoff from a drydock located on the Elizabeth River in Norfolk, Virginia.

The results indicated that the concentrations of dissolved constituents in drydock runoff increased with decreasing flow rate, while solids concentrations exhibited positive correlation to flow rate, suggesting that the mobilization of particulate matter is velocity driven. Approximating the runoff hydrograph due to a storm event using a simple model enabled derivation of the average time that rainwater resides on the drydock surface before …

Modeling A High-Efficiency Ozone Injection Contactor, L. Bernard Garrett Jr.

Civil & Environmental Engineering Theses & Dissertations

Significant research over the last several years has focused on applying modeling equations for estimating design parameters of ozone contactors. Much of this research has focused on fine bubble diffusers, which are the more widely used injection system for ozone contactors in the U.S. A recently developed design incorporates a new ozone injection system called a sidestream venturi injector (SVI) which is used with a co-current downflow column to achieve very high ozone mass transfer efficiencies. A pilot study conducted at the Harwood's Mill water treatment plant in Newport News, Virginia, from June to December 1993 demonstrated the high mass …

The Crash Simulation And Analysis Of The Friendly Mobile Barrier, Bryan Edward Marz

Mechanical & Aerospace Engineering Theses & Dissertations

Mass transportation is an ever increasing alternative being researched and evaluated in today's society. With the increase of demand for such transportation, an increase in safety is also needed. This research entails the analysis of a new idea, The Friendly Mobile Barrier, in railroad crossing barrier design. The design is meant to prevent any approaching vehicle from crossing a railroad track and be survivable for those impacting the barrier.

Research conducted involves the crash simulation and analysis of the Friendly Mobile Barrier. The Friendly Mobile Barrier was analyzed structurally using finite element analysis. An advanced lumped-mass mathematical model software, Crash …

Long-Term Effects Of Seawalls On The Adjacent Nonwalled Beaches Of A Historically Receding Shoreline, Bryan Norton Jones

Civil & Environmental Engineering Theses & Dissertations

Great debate has arisen in recent years over the effects seawalls may or may not have on the erosion rate of a historically receding shoreline. A primary obstacle to the formation of definite conclusions about this subject is the lack of long-term physical data, which must be collected prior to and following seawall construction. This thesis presents the results of a study using 15 years of beach profile data to determine how seawalls influence the existing erosional trends of the beach at Sandbridge, Virginia.

Three analysis methods using three time scales (historic, seasonal, and storms) were used to answer three …

Comprehensive Conjunctive-Use Management Of Connected Surface Water Groundwater Systems Using Stochastic Inputs And Uncertainties, Seshadri Suryanarayana

Civil & Environmental Engineering Theses & Dissertations

A comprehensive conjunctive-use management model is developed. The dynamics of flow and solute transport processes in connected surface water groundwater systems are integrated by a dual programming management model. The governing aquifer flow parameters and streamflows are treated as stochastic random processes. Multiple realizations of the random field are generated and are explicitly incorporated in a non-linear optimization model along with other system, environmental, and management constraints. To facilitate management of large aquifer systems, a linked simulation-optimization approach is used. The simulation program generates the response matrices for flow and transport processes. The management model then determines optimal well discharges …

Energy Use Analysis Of A Multi-Unit Housing Facility A Parametric Study, Brian David Cooper

Mechanical & Aerospace Engineering Theses & Dissertations

In the continuing effort to reduce the energy use of buildings, design engineers and architects are called upon to design facilities which are more efficient and use less energy. The prediction of the energy used by a building's systems and occupants, for different design options and combinations, is an important part of the design of an energy efficient building.

An energy use analysis was conducted to determine the accuracy of a computerized building energy analysis simulation when only preliminary design information is available. Additional studies were made to determine the accuracy of the simulation as more detailed design, construction and …

Organic Matter Characterization Of Virginia Rivers And Reservoirs, Susanne Margaret Lockhart

Civil & Environmental Engineering Theses & Dissertations

Research was conducted on characterizing the DOC characteristics and to discern whether spatial and temporal variations exist in these characteristics as impacted by seasonal, hydrologic or other factors. Data was cumulative of two studies: the State-Wide Survey in which water samples were taken in March and July 1995 from surface waters in four physiographic regions of Virginia and the James River Peninsula Survey concentrating on reservoirs and rivers on the James River Peninsula.

Results illustrate that the two largest fractions of DOC were the hydrophilic and hydrophobic acid fractions. An increase in DOC was observed between the mountains and the …

A Receiving Water Quality Model For Dissolved Metal Runoff From A Floating Drydock, Thomas O. Fenn

Civil & Environmental Engineering Theses & Dissertations

A methodology for modeling the water quality mixing zone of dissolved metal bearing storm water runoff is presented with specific application to floating drydocks in a tidal estuary. The method relies upon a solution of the mass balance equation as contained in the computer program, Water Quality Analysis Simulation Program (WASPS), an Environmental Protection Agency (EPA) model. Separate applications are presented for dissolved metal and solid settling to optimize the WASPS program capabilities.

WASPS provides the capability to evaluate the mass balance equation in a finite difference scheme applied over a large number of small volume segments. The program may …

A One-Dimensional Model For Storm Breaching Of Barrier Islands, Cheol Shik Shin

Civil & Environmental Engineering Theses & Dissertations

A set of numerical models is developed for simulating the four stages of barrier breaching characterized by one horizontal spatial dimension.

The SBEACH model is employed for the first stage of dune/beach erosion. The Lax-Wendroff two-step explicit scheme for Stage II is developed to simulate initiation of ocean flood propagation on initially dry barrier islands and the method of characteristics (MOC), is employed to compute additional boundary data. The development of the Preissmann implicit scheme for water motion and a forward time centered space explicit scheme for sediment motion in Stages III and IV provide a tool to study the …

The Progressive Failure Analysis Of Cut Slope In Anisotropic Strain Softening Soils, Jong Woon Choi

Civil & Environmental Engineering Theses & Dissertations

The failure phenomena in earth structures such as slopes and embankments on clay foundations are a consequence of the formation of failure surfaces.

A finite difference computer code, FLAC (Itasca Consulting Group, 1993), with the isotropic Mohr-Coulomb plasticity model, is used to analyze the undrained progressive failure of a strain softening soil during a slope excavation process. The focus of the study is on the short-term stability of slopes. In the first series of analyses, which are aimed at the evaluation of anisotropic strength effect on slope stability, the isotropic Mohr-Coulomb plasticity model is slightly modified to implement the anisotropic …

A Two-Dimensional Model For Watershed Runoff And Pollutant Transport, Laura Jean Howard

Civil & Environmental Engineering Theses & Dissertations

A two-dimensional mathematical model is developed for the quantitative and qualitative analysis of watershed runoff for a given rainfall event. The runoff is routed through a receiving channel. The model is designed for use on a personal computer. Full documentation is included in the Appendix. The model is capable of accommodating downstream boundary conditions, temporally varied effective rainfall conditions, and spatially varied watershed conditions. Output takes the form of flow depths, discharges, and concentrations. The model was tested for quantity and quality using existing experimental data, and the results are presented herein.

The Influence Of Seawalls On Beach Responses To Storms, Seasonal Transitions And Long-Term Erosion, John Marshall Hazelton

Civil & Environmental Engineering Theses & Dissertations

It has been argued that seawalls have a detrimental effect on the adjacent beaches. These effects may only be noticeable over a period of years or may be short-term effects associated with storms or with seasonal transitions of the beach. Many theories on beach and seawall interaction have been speculative and have lacked actual field or laboratory evidence for their basis.

This study uses four years of monthly and post-storm beach profile data to examine what influences the seawalls at Sandbridge, Virginia have on the adjacent beaches. Long-term effects of the seawalls are analyzed using fourteen years of profile data. …

Development Of A Knowledge-Based System For Wastewater Pipeline Rehabilitation, David Allen Reaves

Engineering Management & Systems Engineering Theses & Dissertations

The purpose of this thesis is to study and develop a knowledge-based system to make decisions for the rehabilitation of wastewater pipelines. Development includes justification for the use of an expert system, data acquisition from knowledge experts, program model development, model testing, implementation and future considerations including expansion. The model is developed and implemented using an expert system shell called XIPlus ®.

This knowledge-based system is designed specifically for the Navy Public Works Center Utilities Department at Norfolk Naval Base in Norfolk, Virginia for making decisions for the rehabilitation of the 50-year-old wastewater collection system. Recent sewer collapses and a …

Landfill Leachate Production And Gas Generation Numerical Model, John Edward Riester Jr.

Civil & Environmental Engineering Theses & Dissertations

Numerous processes occur in landfills which lend themselves to modeling. Many of the processes are mutually interdependent. An unsteady numerical model is developed combining the major processes. The three-dimensional moisture transport equations and boundary conditions are solved using an implicit finite difference scheme. The boundaries are determined through a two-dimensional runoff model for the landfill surface and a one-dimensional leachate liner flow model at the bottom of the landfill. The runoff model accounts for evapotranspiration, runoff, infiltration, and leachate recirculation. Richard's equation is solved for saturated and unsaturated vertical flows and Darcy's Equation is solved for lateral flow between adjacent …

Statistical Variations In Beach Parameter Change Rates For Walled And Non-Walled Profiles At Sandbridge, Virginia, Douglas Allen Bellomo

Civil & Environmental Engineering Theses & Dissertations

The interaction of seawalls {bulkheads) and beaches is a highly controversial subject today. In many locations all over the United States, seawalls have been both praised and ridiculed. It is well documented that Sandbridge, Virginia is, and has been, experiencing shoreline recession. Many believe however, that the recent construction of the seawalls has worsened this existing situation.

Fortunately, historical maps, and beach profiles are available to help determine if this is truly the case. The following defines several visible beach parameters, and describes how these parameters were calculated from two different data sources. Several methods and statistical techniques are then …

Elasto-Plastic Analysis Of Buried Pipelines Subjected To The Large Fault Movement, Luo-Jia Wang

Civil & Environmental Engineering Theses & Dissertations

The responses of buried pipelines subjected to a large fault movement are examined based upon a new non-linear cantilever beam analogy. This analogy assumes that the pipeline in the large deformation zone behaves like a cantilever beam subjected to a transversely concentrated shear at the inflection point and a uniformly distributed soil pressure along the entire span. Tangent modulus approach is adopted to analyze the coupled axial force-bending moment interaction effect on pipeline deformation in the inelastic range. Parametric studies of both tensile and compressive responses of buried pipeline to various fault movements, crossing angles, buried depths, pipe diameters and …

An Experimental Study For The Effect Of Specimen Size On Shear Behavior Of Granular Materials, Clifton Linwood Parker Iv

Civil & Environmental Engineering Theses & Dissertations

An experimental study was undertaken to look into the effect of specimen size on the volumetric behavior of granular triaxial specimens. It was hypothesized that the specimen preparation mold creates a unique particle arrangement near the perimeter of the specimen and thus, for smaller specimen diameter relative to the particle size, it will exhibit a greater effect of the unique particle arrangement on the volumetric behavior. particles was used A single distribution of spherical glass throughout the testing. The tested specimens were 3.6, 2.8, 2.0, 1.4, 1.0, and 0.6 inches in diameter with a fixed two to one specimen height …

Materially Nonlinear Finite Element Analyses Of Trusses And Slab-On-Grade Problems, Moayyad Moh'd Al-Nasra

Civil & Environmental Engineering Theses & Dissertations

The overall approach is to employ the finite-element method along with specified material models to account for material nonlinearity. This study includes two different applications: truss structures and slabs-on-grade.

Procedures for materially nonlinear analysis of truss structures, which apply for both determinate and indeterminate cases are proposed. The proposed procedures are simple and can handle a variety of different stress-strain functions, and the applied load does not have to be incremental. Proposed procedures results are verified with the output of NASTRAN.

A finite-element model for slab-on-grade is introduced. The concrete slab is represented by eight-node brick elements, and the joints …

Inelastic Stability Of Nonproportionally Loaded Steel Sway Beam-Columns And Space Frames, Saleh Ali Eidan

Civil & Environmental Engineering Theses & Dissertations

A comprehensive study of the inelastic stability of steel beam-columns and frames subjected to nonproportional loads is conducted. A set of materially nonlinear differential equations of equilibrium for planar and biaxially loaded beam-columns are first formulated including sidesway. The analysis includes the effect of flexible connections, and initial imperfections in the form of member crookedness and residual stresses. Also, hollow rectangular sections are adopted for the study. First, an iterative numerical solution procedure is formulated for sway beam-columns utilizing central finite-differences with second-order truncation errors. Next, using the beam-column analysis, an inelastic frame analysis procedure is formulated by a conversion …

Seismic Response Of Pipeline Systems In A Soil Liquefaction Environment, Hongzhi Zhang

Civil & Environmental Engineering Theses & Dissertations

This research is a study of the general seismic response behavior of buried pipeline systems during a soil liquefaction process. To aid the design of buried pipelines in a soil liquefaction environment, the purpose of this research is to provide the basic dynamic seismic response of different pipeline systems. Several important parameters such as pipe diameter, buried depth, additional mass and the size of the liquefiable soil zone have been introduced. The pipeline systems under study are cross-types, T-types and straight pipelines, with or without a manhole, buried in a soil liquefiable zone.

Time-varying soil spring constants are used for …

An Experimental Study On Anisotropic Behavior Of Granular Materials, Jong Woon Choi

Civil & Environmental Engineering Theses & Dissertations

Two types of mixtures of glass bead assemblies (large beads and small beads) were used to investigate the source of the anisotropy of granular materials in volume change behaviors during shearing process. Most tests (7 series) were conducted in the conventional triaxial device while a series of the experiments were in the hollow cylinder test device. All the specimens were first isotropically consolidated up to 137.9 kPa and were subjected to shearing in triaxial compression and triaxial extension modes with a constant effective mean normal stress (137.9 kPa). The test results indicated that all the specimens had a strong but …

Parallel-Vector Design Sensitivity Analysis In Structural Dynamics, Yongxing Zhang

Civil & Environmental Engineering Theses & Dissertations

In this study, the design sensitivity analysis is for the purpose of providing constraint derivative information for structural optimization under dynamic loads. Various existing formulations are reviewed, and the direct differentiation method is justified as the best one for design sensitivity analysis in structural dynamics. An alternative formulation for design sensitivity analysis with direct differentiation method is developed. The alternative formulation works efficiently with the reduced system of dynamic equations, and it eliminates the need for expensive and complicated eigenvector derivatives, which is required in the existing reduced system formulation. The relationship of the alternative formulation and the existing reduced …

Parallel-Vector Computation For Geometrically Nonlinear Frame Structural Analysis And Design Sensitivity Analysis, Majdi A. Baddourah

Civil & Environmental Engineering Theses & Dissertations

Parallel-vector algorithms are presented for solving the geometrically nonlinear structural problems and obtaining design sensitivity information. A new algorithm is also presented for parallel generation and assembly of the finite element stiffness and mass matrices. The presented assembly algorithm is based on a node-by-node approach rather than the more conventional element-by-element approach. Three different methods, Newton Raphson, Modified Newton Raphson, and the BFGS, are used in the analysis of the nonlinear structural problems. A study is made to determine the performance of each of the mentioned methods in a parallel-vector computer environment. Medium to large-scale, practical problems are solved to …