Civil Engineering Commons^™

Behavior Of High Strength Concrete And Slender Reinforced Concrete Columns With And Without Steel Fibers, Lin Showmay Hsu

Dissertations

A series of compression tests are conducted on 3 in. by 6 in. cylindrical specimens using a modified testing method that give the complete stress-strain behavior for both plain and fibrous high strength concretes with or without tie confinements. The volume fractions of fiber in the concrete are 0%, 0.5%, 0.75%, and 1.0%, respectively. Empirical equations are proposed herein to represent the complete stress-strain relationships of high strength and high strength fibrous concretes with compressive strength exceeding 10,000 psi. Various parameters are studied and their relationships are experimentally determined. The comparison between the experimental and analytical results shows to have …

The Influence Of Pore Fluids On Shear Strength And Stress-Strain Behavior Of Granular Soils, Prasanna Ratnaweera

Dissertations

When a dry granular soil is subjected to an external load, the stresses are transferred through mineral to mineral contacts. The shear strength of such a soil is governed by its contact properties. Presence of a thin layer of fluid between mineral to mineral contacts in a saturated soil will alter its contact properties. Therefore any change in the physical properties of pore fluid can logically be reasoned to influence the deformation characteristics of granular soils.

To investigate the influence of pore fluid viscosity on shear strength and stress-strain behavior of a soil, a series of consolidated drained triaxial tests …

A Modified Approach To Flood Prediction In Urban Watersheds, Joseph Ofungwu

Dissertations

The purpose of this dissertation was to develop a better method for dealing with the problems of flood prediction in Urban Watersheds. It has long been realized that urbanization activity such as increased imperviousness, drainage improvements, etc. increases runoff volumes. Therefore, traditional flood prediction methods using the Log Pearson III distribution underestimate flood frequencies when applied to urban watersheds without modification.

In attempt to compensate for the effects of urbanization on streamflow, previous workers usually employed regional analysis techniques involving a number of different watersheds at various degrees of urbanization. Results obtained by this approach leave room for improvement primarily …

Behavior Of Square And L-Shaped Slender Reinforced Concrete Columns Under Combined Biaxial Bending And Axial Compression, Wen Hu Tsao

Dissertations

A numerical analysis was developed to evaluate the complete load-deflection and moment-curvature relationships for square and L-shaped slender reinforced concrete columns subjected to biaxial bending and axial load. This computer model can be used for any cross section geometry and material properties of normal concrete. The analysis was based on a deformation control and both the ascending and descending branches of curves can be studied. The finite difference method was introduced to calculate the deflections which satisfy the compatibility equations. Six square slender columns and eight L-shaped slender columns were tested to compare their experimental load-deformation results with the analytical …

Bond And Fatigue Characteristics Of High-Strength Cement-Based Composites, Somboon Chimaphant

Dissertations

The results of a series of tests on a variety of high strength cementitious composites yield a model from which an empirical equation of general normalized pull-out stress vs. pull-out displacement relationship is developed. A new variable named the "Brittleness Index" is defined and used in the proposed equation. Additionally, the concept of maximum strain is used to predict the fatigue life of high strength concrete.

Three sizes of deformed bars and two types of steel fibers with four different volume fractions were used to observe bond-slip and pull-out characteristics of high strength concrete. The results indicate that the maximum …

Air Stripping Of Volatile Organic Contaminants Using Rotating Disc Contactor, Kai-Ping Hsueh

Dissertations

Previous studies have suggested that the transfer of VOCs to the atmosphere by air stripping may be a convenient and potentially cost-effective method to remove these compounds from the water. A Rotating Disk Contactor (RDC), similarly to other aeration devices, can provide intimate contact between the VOC-bearing water and air. It is believed that under carefully selected operating conditions, the RDC system are more competitive with packed tower than other aeration methods. The objectives of this study were to evaluate the feasibility of using the RDC to strip VOCs from the contaminated water and to develop a mathematical model to …

Permeability And Volume Change Characeristics Of Bentonite-Sand Mixes In A Contaminant Environment, Yuan-Hsun Wu

Dissertations

This research was conducted to study the characteristics of permeability and volume change of bentonite-sand mixes due to contaminants. The soil specimens consisted of clean sand, bentonite, and fly ash. Test liquids included seven diluted organic and inorganic chemicals and a landfill leachate.

Index tests included liquid limit, expansion, cracking, and sedimentation tests. Expansion tests proved to be the most useful for permeability evaluation in a contaminant environment.

The conventional consolidometer permeameter and flexible wall permeameter proved to be not completely satisfactory for testing soft bentonite mixes. A triple ring permeameter was developed to compensate for the limitations of these …

Adsorption Of Organic Compounds By Microbial Biomass, Ariamalar Selvakumar

Dissertations

The adsorption of hazardous organic compounds such as phenol, 2-chlorophenol, 2-nitrophenol, chlorobenzene, and ethylbenzene onto two types of inactive microbial biomass (activated sludge and nitrifying bacteria) was studied. The adsorption isotherms could be expressed by the Freundlich adsorption isotherm and were found to be nearly linear over the range of concentrations (50 - 200 mg/1) studied. Desorption studies showed that the adsorption process was partially reversible. Heat of sorption was estimated and indicate that the biosorption process involves a physical rather than a chemical mechanism. The adsorptive capacity of biomass is about two to three orders of magnitude less than …

Removal Of Fluoborate From Electroplating Rinse Water By Ion Flotation, Ray Haralson

Dissertations

A problem exists in the removal of fluoborate from electroplating waste rinse water. The normally used waste treatment methods are not effective and the vacuum evaporation process now being tried is expensive and energy intensive. Experiments were conducted and an alternative treatment process which shows substantial removals of the fluoborate was developed. This can be effectively done using ion flotation techniques. A broad range of surfactants were screened for usefulness in this process and it was found that an aliphatic amine acetate was usable in this process. Operating parameters for the process were investigated, and the removal mechanism was determined …

Mathematical Modeling And Analytical Solutions Of Dissolved Oxygen And Biochemical Oxygen Demand Profiles Under Three-Dimensional, Unsteady-State Conditions, Uing Woong Kim

Dissertations

Mathematical models describing the temporal and spatial distribution of Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD) for both pervious and impervious channel conditions in 3-dimensions have been constructed, and their analytical solutions were obtained. The solutions were implemented through the application of a digital computer, and their results are presented.

It has been found that there are significant differences in terms of DO and BOD distribution with respect to time and space in relatively deep and wide channels, thus necessitating the use of a 3-D, unsteady-state model.

An Investigation Of The Dynamic Response Of The Activated Sludge Process, Tin-Bai Pan

Dissertations

A new mathematical model, derived from first principles of mass balance, is proposed for describing the mass transfer response of an activated sludge aeration tank in terms of a fluidized bed. The operational data to verify the proposed model were taken from an existing conventional wastewater treatment plant and a bench scale pilot plant.

The mass transfer rate, (K_dA_s), was presented by an empirical dimensionless group function as follows:

((K_dA_s)D_p/D_v) = fA_c (uD_p/ν)a ((ν/D_ν)(MLSS))^b

Or

Sh = f(A_c/A_s ) …

Development And Verification Of A Laboratory Model For Use In The Study Of A Continuous Flow Pressurized Activated Sludge Process, Wayne Frederick Nolte

Dissertations

Investigations concerning the responses of domestic wastewater treated at elevated pressures have demonstrated an acceleration in the rate of biological assimilation of the waste material. The literature is not extensive, but presents much conflicting data. There has been a lack of a coherent approach to the investigation of pressure in wastewater treatment. This demonstrates the need for standard testing apparatus and procedures.

A bench scale pressurized activated sludge process was designed and constructed. The apparatus was tested over a broad range of conditions and was found to give reproducible results. Kinetic responses of the pressurized process are presented.

The Use Of Natural Sorbents For The Treatment Of Industrial Sludge Leachate, Mung Shium Jack Sheih

Dissertations

A sorbent treatment process has been developed which uses natural clay soils and fly ashes as sorbents in the treatment of the hazardous contaminants of potential sludge leachate emanating from industrial landfills. Natural sorbents (i.e., vermiculite, illite, kaolinite, zeolite, acidic and basic fly ashes) were evaluated for the removal of specific cations, anions, and organics from leachates generated from three industrial sludges (i.e., calcium fluoride, metal finishing, and petroleum). The laboratory results indicate that, rather than a single sorbent, a combination of acidic and basic sorbents in a layered system is required to reduce for the measurable contaminants present in …

Paper Recycling : Recovery Of Secondary Fibers By Selective Wettability, Gary Keith Welshans

Dissertations

A separation process has been developed which recovers similar paper grades from a mixed stock by selective wettability. This process capitalizes on the various paper additives which are intended to resist water wetting and result in paper flotation. While water can be used to achieve many desirable paper separations, the detention times required are excessive, and therefore, limit any industrial application. Surface-active agents, in low concentrations, can be used advantageously by reducing the detention times for all paper while the structure of the surfactant can be used to selectively recover similar papers over a controlled time period. Detention times have …

Nonlinear Buckling Of Deep Cylindrical Shell Panels With Imperfections, Madhusudan H. Jhaveri

Dissertations

The work presented in this dissertation is devoted to the analysis of nonlinear buckling of thin cylindrical shells with imperfections. The nonlinearity of the problem treated in this dissertation is that associated with large displacements in the linear elastic range. The method used is not restricted by the magnitude of the displacements provided that the strains do not exceed the limit of proportionality.

Thus, based upon the large deflection theory, cylindrical shell panel is investigated for buckling under the action of uniform external pressure. Certain higher order infinitesimal terms which are usually neglected in the shallow shell theories, have been …

An Analysis Of The Passenger Vehicle Interface Of Street Transit Systems With Applications To Design Optimization, Walter H. Kraft

Dissertations

This research analyzes the Passenger Vehicle Interface of the street transit systems and presents applications for design optimization. The Passenger Vehicle Interface (PVI) is defined as the interaction between the passenger and vehicle elements of the street transit system.

Human observer and photographic studies were conducted in 17 cities in the United States and Canada to measure the time for queues of passengers to board various transit vehicles. The data were analyzed by considering seven factors that affect the Passenger Vehicle Interface: Human Factor, Modal Factor, Operating Practices, Operating Policies, Mobility, Climate and Weather, and Other System Elements. Those effects …

Optimal Planning Of Fixed Route Bus Transit Systems : A Systems Approach, Young Lee

Dissertations

A new bus transit planning tool is developed for application in determining operating policies of a fixed-route bus transit system. The objective of the study is to model a bus transit system which functions under time-varying passenger demands and service characteristics.

The two phase transit model developed in this research is intended for use as a mass transit planning tool, to solve transit problems confronting the mass transit planner. The model is used to compute cost differentials in transit system options. These alternatives of expanding, abandoning or modifying service depend upon the service frequency, fleet size and other system attributes …

A Simulation Modeling Approach To Central City Dynamics, Leonard William Schaper Jr.

Dissertations

This dissertation describes a computer simulation model of a central city with emphasis on its application to Newark, New Jersey. The work begins with a review of the Forrester Urban Dynamics Model; the first attempt to simulate the entire system of the city. The objections to this model which have appeared in the literature are discussed, and the model is viewed in the light of other work in the field. A set of guidelines to aid the "second generation" model building effort is developed. The actual construction of a model which attempts to follow these guidelines is described. First, the …