Master of Science / Department of Architectural Engineering and Construction Science / Kimberly W. Kramer / Reinforced concrete is a common building material used for blast resistant design. Adding fibers to reinforced concrete enhances the durability and ductility of concrete. This report examines how adding steel fibers to reinforced concrete for blast resistant design is advantageous. An overview of the behavior of blasts and goals of blast resistant design, and advantages of reinforced concrete in blast-resistant design, which include mass and the flexibility in detailing, are included in the blast resistant design section. The common uses for fiber-reinforced concrete, fiber types, and properties of fiber reinforced concrete varying with fiber type and length, and concrete strength are discussed in the fiber-reinforced concrete section. Two studies, Very High-Strength Concrete for Use in Blast-and-Penetration Resistant Structures and Blast Testing of Ultra-High Performance Fiber and FRP-Retrofitted Concrete Slabs, are reviewed. Lastly, the cost, mixing and corrosion limitations of using steel fiber-reinforced concrete are discussed. Reinforced concrete has been shown to be a desirable material choice for blast resistant design. The first step to designing a blast resistant reinforced concrete structure is to implement proper detailing to ensure that structural failures will be contained in a way that preserves as many lives as possible. To design for the preservation of lives, a list of priorities must be met. Preventing the building from collapse is the first of these priorities. Adding steel fibers to concrete has been shown to enhance the concrete’s post-crack behavior, which correlates to this priority. The second priority is reducing flying debris from a blast. Studies have shown that the failure mechanisms of steel fiber reinforced concrete aid in reducing flying debris when compared to conventional reinforced concrete exposed to blast loading. The major design considerations in designing steel fiber reinforced concrete for blast resistant design include: the strength level of the concrete with fiber addition, fiber volume, and fiber shape. As research on this topic progresses, the understanding of these factors and how they affect the strength characteristics of the concrete will increase, and acceptance into the structural design industry through model building codes may be possible.

The integration of photocatalytic advanced oxidation into solar disinfection is a robust method of improving the microbial and chemical quality of treated water. This study evaluates the performance of photocatalytic solar irradiated batch reactors through an analytical model that reduces treatment parameters by simplifying photoreactor geometry and relating performance to reactor configuration. Accompanying experiments compare the performance of titanium dioxide coated foams of varying pore size to suspended and fixed film configurations through degradation of organic dyes (acid orange 24 and methylene blue), Escherichia coli, and 1,4-dioxane. Results indicate that a catalyst immobilized on a foam support can match the performance of a suspension due to effective mass transport and association between analyte and foam. Additionally, the potential treatment capacity of solar photocatalysis was compared to conventional treatment methods. Results of this comparison stress the fundamental limitation of solar photocatalysis if visible light wavelengths are not harnessed.

The EPA Lead and Copper Rule set action limits for lead and copper concentrations in drinking water, but accelerated corrosion of lead in distribution systems due to a galvanic connection to copper. Prior research has demonstrated that the effects of galvanic corrosion can be controlled by water chemistry. This study not only investigated the main effects of alkalinity, natural organic matter (NOM), nitrate, disinfectant and inhibitor to galvanic corrosion, but also the interplay between these factors. A 2-level factorial (2v5-1) design was adopted which resulted in 16 testing conditions. Results of bench-scale experiments using static pipes with lead and copper segments demonstrated that alkalinity, disinfectant, inhibitor and alkalinity-inhibitor interaction had a significant impact on galvanic current. The significant factors affecting total lead release were alkalinity, NOM, disinfectant, alkalinity-inhibitor interaction, NOM-nitrate interaction, NOM-disinfectant interaction, NOM-inhibitor interaction, nitrate-disinfectant interaction and disinfectant-inhibitor interaction.

The integration of photocatalytic advanced oxidation into solar disinfection is a robust method of improving the microbial and chemical quality of treated water. This study evaluates the performance of photocatalytic solar irradiated batch reactors through an analytical model that reduces treatment parameters by simplifying photoreactor geometry and relating performance to reactor configuration. Accompanying experiments compare the performance of titanium dioxide coated foams of varying pore size to suspended and fixed film configurations through degradation of organic dyes (acid orange 24 and methylene blue), Escherichia coli, and 1,4-dioxane. Results indicate that a catalyst immobilized on a foam support can match the performance of a suspension due to effective mass transport and association between analyte and foam. Additionally, the potential treatment capacity of solar photocatalysis was compared to conventional treatment methods. Results of this comparison stress the fundamental limitation of solar photocatalysis if visible light wavelengths are not harnessed.

The EPA Lead and Copper Rule set action limits for lead and copper concentrations in drinking water, but accelerated corrosion of lead in distribution systems due to a galvanic connection to copper. Prior research has demonstrated that the effects of galvanic corrosion can be controlled by water chemistry. This study not only investigated the main effects of alkalinity, natural organic matter (NOM), nitrate, disinfectant and inhibitor to galvanic corrosion, but also the interplay between these factors. A 2-level factorial (2v5-1) design was adopted which resulted in 16 testing conditions. Results of bench-scale experiments using static pipes with lead and copper segments demonstrated that alkalinity, disinfectant, inhibitor and alkalinity-inhibitor interaction had a significant impact on galvanic current. The significant factors affecting total lead release were alkalinity, NOM, disinfectant, alkalinity-inhibitor interaction, NOM-nitrate interaction, NOM-disinfectant interaction, NOM-inhibitor interaction, nitrate-disinfectant interaction and disinfectant-inhibitor interaction.

Experimental research was conducted to investigate the influence of axial load and prestress on the shear strength of web-shear critical reinforced concrete elements. The ability of two design codes, the ACI code and the CSA code, to accurately predict the shear strength of web-shear critical reinforced concrete elements was investigated through two sets of experiments performed for this thesis, the panel tests and the beam tests. The experimental results indicated that the CSA code provided better predictions for the shear strength of web-shear critical reinforced concrete members subjected to combined axial force and shear force than the ACI code. A total of six panels, reinforced almost identically, were tested under different combinations of uni-axial stress and shear stress. In addition to the panel tests, a total of eleven I-shaped beams, with the same web thickness, were tested under different combinations of axial force and shear force. The parameters for these beams were the amount of longitudinal reinforcement, the amount of transverse reinforcement, and the thickness of the flanges. The beams were simply supported, but the loading geometry was specially designed to simulate the loading conditions in continuous beams near points of inflection. The experimental results from the panel tests and the beam tests followed a similar trend of variations. Both the inclined cracking strength and the ultimate shear strength were increased by compression and were reduced by tension. The specimens subjected to very high compression failed explosively without developing many cracks. The inclined cracking strength could be predicted with good accuracy if the influence of the co-existing compression on the cracking strength of the concrete and the non-uniform distribution of the stresses over the depth of the cross-section were considered. The strength predictions using the ACI code for these tests were neither accurate nor consistent. The ACI code was unconservative for members subjected to compression and was excessively conservative for members subjected to tension. In contrast, the strength predictions using the CSA code for these tests were generally conservative and consistent. The CSA code accurately predicted the response of specimens subjected to compression and was somewhat conservative in predicting the shear strength of specimens subjected to tension.

The thesis numerically explores the use and behavior of Active Hydraulic Devices (AHDs), creating a new capability to simulate and control a pipe system’s transient performance. Automatic control valves are the first type of AHDs studied in this research. Due to the challenges inherent in the design of a pressure relief valve (PRV), the general principles of PRV use and selection are studied along with the system’s response to the PRV parameters. A new application of PID (proportional, integral and derivative) control valve is envisioned that combines a remote sensor at the upstream end of a pipeline to create a non- or semi- reflective boundary at the downstream end. Case studies show that, with such a boundary, the reflection and resonance of pressure waves within the pipeline are sometimes eliminated and invariably limited. The second type of AHDs studied in this research is the governed hydro turbine, the most complicated hydraulic component in terms of transient analysis and waterhammer control. A complete numerical model is developed for the turbine installations in either urban water networks or conventional hydropower generation systems. Using the model, transient simulations for several realistic hydro projects are presented along with various transient control measures.

Doctor of Philosophy / Department of Civil Engineering / Hayder A. Rasheed / Spherical shells are widely used in aerospace, mechanical, marine, and other industrial applications. Accordingly, the accurate determination of their behavior becomes more and more important. One of the most important problems in spherical shell behavior is the determination of buckling loads either experimentally or theoretically. Therefore, in this study some elastic and plastic buckling problems associated with spherical shells are investigated. The first part of this research study presents the analytical, numerical, and experimental results of moderately thick and thin hemispherical metal shells into the plastic buckling range illustrating the importance of geometry changes on the buckling load. The hemispherical shell is rigidly supported around the base circumference against horizontal translation and the load is vertically applied by a rigid cylindrical boss (Loading actuator) at the apex. Kinematics stages of initial buckling and subsequent propagation of plastic deformation for a rigid-perfectly plastic shell models are formulated on the basis of Drucker- Shield's limited interaction yield condition. The effect of the radius of the boss used to apply the loading, on the initial and subsequent collapse load is studied. In the numerical model, the material is assumed to be isotropic and linear elastic perfectly plastic without strain hardening obeying the Tresca or Von Mises yield criterion. Finally, the results of the analytical solution are compared and verified with the numerical results using ABAQUS software and experimental findings. Good agreement is observed between the load-deflection curves obtained using three different fundamental approaches. In the second part, the Southwell’s nondestructive method for columns is analytically extended to spherical shells subjected to uniform external pressure acting radially. Subsequently finite element simulation and experimental work shown that the theory is applicable to spherical shells with an arbitrary axi-symmetrical loading too. The results showed that the technique provides a useful estimate of the elastic buckling load provided care is taken in interpreting the results. The usefulness of the method lies in its generality, simplicity and in the fact that, it is non-destructive. Moreover, it does not make any assumption regarding the number of buckling waves or the exact localization of buckling

Master of Science / Department of Civil Engineering / Dunja Peric / The purpose of this research was to investigate the effects of drying on the strength gain of masonry sand stabilized with a co-product from wood pulping called calcium lignosulfonate. Lignin is an amorphous polymer found in plant cell walls. It provides protection against disease and allows the transport of water and nutrients. Adhesive properties of lignin generated interest in adding its modifications to soils as means to prevent erosion from wind and vehicle traffic on unpaved roads. Lignin has the potential to become a more sustainable alternative to traditional stabilizers because its source is renewable and abundant, and its toxicity is negligible. Extensive testing has recently been completed to quantify the stress-strain relationships and Mohr-Coulomb strength parameters of sand- calcium lignosulfonate-water (S-CaL-W) mixes at early age (Bartley, 2011). The experimental program consisted of performing Standard Proctor Tests to determine maximum densities and optimum moisture contents for mixes having different gravimetric lignin contents and direct shear tests on selected sample configurations. Based on these results, it was decided to conduct shear strength testing of the samples containing 4%, 6% and 9% of calcium lignosulfonate after they had been exposed to air drying. To this end, responses of the selected sample configurations to drying at 71° F and 27% relative humidity were measured to determine the target water contents for shear strength testing. Drying curves were obtained by plotting the measured water content or water to CaL ratio versus the elapsed time. Drying times for shear strength were chosen based on how long it took the moisture contents to decrease by specified levels. The available results of direct shear tests show that drying significantly increases both the cohesion and the friction angle of the S-CaL-W mixes with respect to the early age cohesion and friction angle. In addition to the direct shear test program a laboratory compaction test was conducted on CaL and water only, thus providing the maximum dry density of CaL and the corresponding optimum water to CaL ratio. It is also noted that relative humidity was discovered to be the limiting factor in the strength gain of S-CaL-W mixes. The reasons behind its sensitivity to water are due to the presence of HPLC sugars within the calcium lignosulfonate structure. These sugars hold the water through the chemical interaction of the sugars with hydrogen ions and water molecules.

Master of Science / Department of Civil Engineering / Hayder A. Rasheed / Nowadays, using the technology of FRP strengthening has become acknowledged by engineers and has reached a full acceptance. However, researchers are always looking for improvement in performance. In this study, external bonding of GFRP and near surface mounting of regular steel bars are combined to improve the behavior, delay the failure and enhance the economy of the strengthening. E-Glass FRP is selected due to its inexpensive cost and non-conductive properties to shield the NSM steel bars from corrosion. On the other hand, the use of NSM bars gives redundancy against vandalism and environmental deterioration of GFRP. An experimental program was conducted in which four full scale T beams were designed and built. All four specimens were fabricated with Grade 70 steel reinforcement and 8000 psi concrete. Only one beam was loaded beyond first cracking then exposed to highly concentrated deicing salt water to accelerate the corrosion process. All beams were tested by monotonic loading until failure. The load rate was 1 kips/min. The first specimen is tested as a control beam failing at about 15 kips. The second specimen is strengthened using two #5 steel NSM bars and 1 layer of GFRP, both extending to the support. This beam failed at 38.4 kips by GFRP debonding. The third specimen is strengthened with the same system used for the second beam. However, the NSM steel bars were cut short covering only 30% of the shear-span while the GFRP was extended to the support. This beam failed at 25.9 kips by GFRP debonding and NSM delamination due to the lack of sufficient development of the NSM steel bars and the shear stress concentration at the steel bar cut off point. Nevertheless, the fourth beam is strengthened with the same system used for the third beam. The fourth specimen was exposed to severe attack of deicing salt by immersing it in concentrated deicing salt solution for three continuous months. In order to accelerate the corrosion process, the beam was loaded beyond its cracking load before the corrosion procedure. After the completion of the three months, the beam was tested monotonically to failure. It failed at 23.2 kips indicating that some deterioration might have taken place. The failure mode was by GFRP debonding and NSM delamination like the case of Beam 3.However, it was observed after failure that the NSM bars were very well protected by the surrounding epoxy.