Engineering Commons^™

The Study Of Permeability In Concrete, Jie Yuan

Theses

In this study, samples of regular, high performance, expansive and the polymer concrete and mortar were prepared for test of permeability and mechanical property. In the permeability measurement, water and an aqueous chemical solution were employed as the permeant.

The test results of the samples, ranging from 5.7 x 10-9 cm/sec to 1.0 x cm/sec for the permeability and 3800 psi to 10600 psi for compression strength, indicated that the polymer coated concrete has the lowest permeability among the concretes and high performance concrete has the highest compression strength . The finding leads to the possibility that a high strength …

Local Stresses On Lateral Pipe-Nozzle With 45 Degree Angle Intersection, James Jin Xu

Dissertations

This dissertation presents a comprehensive study of local stresses, due to internal pressure around a pipe-nozzle with 45 degree angle intersection_ The resulting circumferential and longitudinal stresses on the pipe around the pipe-nozzle region are normalized as local stress factors and plotted as function of beta, β, (the radius of the nozzle/the radius of the pipe) and gamma, y, (the radius of the pipe/the thickness of the pipe) through the finite element method. The range of beta, [3, is from 0.1, to 1.0, and gamma, y, from 10 to 300. Comprehensive studies were made for the boundary parameters, such as …

Stress-Strain Behavior Of High Strength Concrete Cylinders, Danqing Chen

Theses

Due to the recent development of high strength concrete in engineering and construction, it has become more important to study the behavior of materials in structures.

No results have been previously published in the literature regarding the influence of aspect ratio in plain high strength concrete cylinders on stress-strain behavior under uniaxial compression.Thus at present study, compression tests were conducted on 3x6 in., 3x9 in., and 3x12 in. plain high strength concrete cylinders to study their stress-strain behavior. Plain normal strength concrete cylinders were also tested and used for comparative study.

Based on the present investigations, attempting to obtain a …

Behavior Of Concrete And Slender Reinforced Concrete Columns Under Cyclic Axial Compression With Bidirectional Eccentricities, Byong Youl Bahn

Dissertations

A rational analysis of reinforced concrete (R/C) structures requires satisfactory modeling of the behavior of concrete under general loading patterns. The behavioral characteristics of concrete dominantly depends upon its load history. For the study of concrete behavior, parametric study and experimental investigation into the behavior of concrete under load history of random cycles are performed. Through parametric study, the applicability of the previous concrete models is examined and a physically motivated modeling for the cyclic stress-strain relationships is proposed. The present modeling of concrete under general cyclic loading is initiated to provide substantial applicability, flexibility of mathematical expressions and furthermore …

Tensile Behavior Of Concrete And Mortar Under Direct Impact Tensile Load, Kayumars Emad

Dissertations

Structures are often subjected to impact loadings during their lifetime. Most structural specifications including the special provisions for seismic design in the current ACI building codes, have been developed on the basis of quasi-static assumptions. Cement composites are strain rate sensitive materials therefore, their properties determined under quasi-static condition should not be used to predict their performance under high strain rates.

The objectives of this investigation are:

• to develop a standard test set-up for direct tensile testing of cementitious composites.
• to study the tensile behavior of mortar and concrete under direct impact tensile load.
• to develop a simplified formula to …

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 …

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 …

On Local Stresses And Spring Constants Of A Sphere-Nozzle Connection, Ban-Li Lyow

Dissertations

This dissertation studies the local stresses and spring constants of a spherical shell with a nozzle attachment when it is under various loadings, namely radial force, overturning moment, horizontal shear force, and torsional moment. Because of the mathematical difficulty in modeling the nozzle-sphere configuration, particularly with nozzle opening, the finite element method (ANSYS package) is utilized in this study. The model used in this study is a quadrilateral thin shell element model when the γ_s (spherical radius/thickness) value is larger than 10. Otherwise the isoparametric solid element is used. The resulting stresses are basically biaxial state of stresses. It …

On Local Stresses And Spring Constants Of Pipe-Nozzle Connection, Hson-Chih Sun

Dissertations

This thesis presents a comprehensive study of local stresses and spring coefficients of pipe with a nozzle connection, analyzed by the finite element method (FEM). Six types of loading are discussed: radial force, circumferential moment, longitudinal moment, circumferential shear force, longitudinal shear force, and torsional moment.

For the local stresses, the bending and membrane stress factors due to each of these loadings are presented in a series of plots with various gamma (piping radius/thick-ness) and beta (nozzle radius/pipe radius) values. These stress factors will readily replace those previously published in WRC No. 107. This work not only gives more accurate …

Stress Analysis Of A Stepped Shaft With A Keyway, Irfan Hussain Sabir

Theses

A stress concentration case which is encountered in practice more than any other is the shoulder fillet. Shafts, axles, spindles, rotors etc., usually involve, in each case, a number of diameters connected by shoulders with fillet radii and very often it is necessary for a keyway to be near a shoulder. The objective in this study is to analyse the stresses in a shouldered shaft with a keyway subjected to an axial tensile load and to study the dependence of the keyway-end stresses on the distance between the shoulder fillet and the keyway end. This is done by performing a …

Behavior Of Thin-Walled Channel Shaped Reinforced Concrete Columns Under Combined Biaxial Bending And Compression, Subash Yalamarthy

Theses

Next to rectangular, circular and L shapes, Channel section may be the most frequently encountered reinforced concrete columns since they can be used as box wall for elevators. Nevertheless, information about the load deformation behavior is not generally available to structural engineers. Most of the investigations have been emphasized on the ultimate strength of column sections under combined biaxial bending and axial compression and the resulting interaction surface. No attention is paid to load deformation behavior.

Current code provisions do not provide adequate guidelines for assessing the strength and ductility of biaxially-loaded reinforced concrete columns. Therefore, this investigation is aimed …

Behavior Of Tee-Shaped Reinforced Concrete Columns Subjected To Biaxial Bending And Axial Compression, Antoun Romanos Nader

Theses

The investigation deals with the effect of eccentric loading on the moment-curvature relationship of reinforced concrete tee columns.

The test program consisted of two series of tee-shaped reinforced concrete columns, loaded biaxially at constant angle from the principle axes. Their end conditions were assumed to be pinned-ended.

Loads, at constant rate, were gradually applied until failure. At each loading stage, measurements were made for the strains and deflections at the mid span section.

The experimental and theoretical results of the load- deformation and moment-curvature were compared and found that the analytical approach proposed by Hsu is applicable to irregular sections …

Analysis And Tests [Of] L-Shaped Reinforced Concrete Column Under Combined Biaxial Bending And Axial Compression, Alaedin Majlesi

Theses

A total of five tests on biaxially loaded column specimens were conducted to investigate the complete behavior of load-deformation characteristics from zero load until failure. The specimens were tested under horizontal position with 60 ton hydrolic jack. Pin end was used for both ends to obtain higher accuracy of plotting curves.

Two specimens were tested with dial gages to obtain load-deflection curves and the other three specimens were tested with demec and strain gages to obtain load strain and moment-curvature curves. The strain gages were measured by weston bridge and deme-gages were measured by mechanical dial gage.

The above moment-curvature …

Failure Surface For L-Shaped Reinforced Concrete Short Columns, Mon-Chen Liu

Theses

Combined bending and axial compression for L-shaped reinforced concrete short columns is a common problem. But the present ACI Building Code (ACI 318-77), handbooks and texbooks pay no attention to this problem. A numerical analysis and computer program developed by Hsu fora reinforced concrete member subject to biaxial bending and axial load has been used Using this computer program, the interaction diagrams and failure surface were developed for L-shaped members under combined bending and axial compression. A comparison between theoretical and experimental results was included to examine the validity of failure surface.

The Creep And Stress Relaxation Behavior Of Silver Bearing Copper Wire, Alfred Fox

Theses

Creep and stress-relaxation experiments were performed on silverless and silver bearing copper in the temperature range 73F to 250F. The creep experiments were conducted at constant load and temperature, the stress-relaxation tests at constant total strain and temperature for a total time period of 1000 hours. The effect of silver addition of up to 0.2 percent w/o (60oz per ton) on the creep and stress-relaxation behavior of spectrographically pure copper (99.999+ Cu) as well as on that of tough pitch and oxygen free coppers of lesser purity was studied. Spectrographically pure copper was found to be much more susceptible to …

Dynamic Stress Concentrations About An Epilliptical Discontinuity In An Elastic Solid, Kenneth Roy Schroll

Dissertations

The redistribution of dynamic stresses caused by the presence of an elliptical discontinuity in an infinite isotropic homogeneous elastic solid is examined. The solutions are obtained for the special cases of the rigid immovable inclusion and the vacuous cavity inclusion, and numerical results are presented.

The solutions to the wave equations in elliptical coordinates are expressed in series of the elliptical geometry eigenfunctions. Application of the boundary conditions, vanishing displacements for the rigid immovable inclusion and vanishing stresses for the cavity inclusion, yields in each case two infinite sets of linear algebraic equations for the expansion coefficients of the series …