Doctor of Philosophy / Civil Engineering / Mustaque A. Hossain / Geocellular confinement systems (geocells), three-dimensional honeycomb-like structures containing an infill of available materials such as sand or crushed limestone, vastly improve shear strength of infill materials. Geocells are potential solutions for challenges associated with low-volume paved road reconstruction. The objectives of this study were to test geocell designs with various infill materials and a thin hot-mix asphalt overlay under full-scale traffic load and to numerically model this problem. Therefore, eight pavement test sections were constructed at the Civil Infrastructure System Laboratory at Kansas State University, Manhattan, Kansas. Repeated loads (80-kN, single axle) were applied to the pavement sections using an accelerated pavement testing machine till failure. Pavement sections were modeled three-dimensionally using Abaqus, a commercially available finite element software package. Effects of geocell height and location were simulated in the geocell-reinforced bases, and pavement structures were modeled as three-layered systems. Results showed that proper geocell height, infill material and cover depth to protect the geocells during construction are necessary to ensure long-term performance of geocell-reinforced pavements. Such pavement structures with low- quality infill materials can perform as well as conventionally-constructed pavement structures.

Master of Science / Civil Engineering / David R. Steward / With an increasing population, municipalities in the United States are struggling to secure safe, reliable water sources for future water demands. Alternative water sources are being considered to improve the overall water management picture. Wastewater reuse, reusing wastewater effluent for beneficial purposes, is an alternative water source that is gaining popularity in the United States. In this study a theoretical framework was developed to enable a region to quickly assess the feasibility of reusing wastewater for irrigation needs. Three criteria were established for the framework; they are, regulations and guidelines for reuse, adequate flow ratio, and cost benefit analysis. As a region moves through the framework and criteria a list of feasible wastewater facilities and end users are established. A model was developed for the cost benefit analysis based on regional input. As regulatory frameworks and economic factors evolve over time the model can be updated to assess how these changes will affect water reuse in a region. The model will provide a useful tool for a region to integrate wastewater reuse into the water resource management process. The Lower Arkansas River Basin (LARK) was highlighted by the Kansas Water Office as a region that should investigate the role of reuse in water conservation. Results from this report indicate 963 million gallons per year (MG/yr) of wastewater effluent could feasibly be used to irrigate 9 hole and 18 hole golf courses in the region. The results determined that any 18 hole golf course within a 15.9 mile radius of a wastewater treatment facility in the LARK could payback the capital costs for wastewater reuse within 10 years. This information is a useful tool for the region to start the discussion for implementing wastewater reuse in the region. The results from this report indicate wastewater reuse for golf course irrigation is economically feasible in the LARK. Establishing a safe reliable water source for the future is paramount to the future of Kansas. Future research is needed to determine how the wastewater diversion affects the environmental balance of the permitted discharge location.

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.

Master of Science / Department of Civil Engineering / Hayder Rasheed / The technology of FRP strengthening has matured to a great extent. However, there is always room for performance improvements. In this study, external bonding of GFRP and near surface mounting (NSM) of regular steel bars is 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 the GFRP. An experimental program is conducted in which four rectangular cross-section beams are designed, built, and tested in four-point bending. The first beam is tested as a control beam failing at about 12.24 kips. The second beam is strengthened using two #5 steel NSM bars and 1 layer of GFRP, both extending to the support. This beam failed at 31.6 kips. The third beam is strengthened with the same system used for the second beam. However, the NSM steel bars were cut short covering 26% of the shear-span only while the GFRP was extended to the support. This beam failed at 30.7 kips due to reaching the full flexural capacity of the section at the NSM bars cut off point and the shear stress concentration at the steel bar cut off point. The fourth beam was strengthened with same system as the third beam but then submerged in a highly concentrated saline solution for six months and then tested. This beam failed at a maximum applied load of 29.8 kips, which shows that the GFRP sheet provided good corrosion resistance from the saline solution.

Master of Science / Department of Civil Engineering / Kyle Riding / The relationship between in-place concrete strength and permeability with concrete cylinder strength and permeability with time is of interest - especially when supplementary cementitious materials (SCMs) are used. A joint research project between The University of Kansas was undergone to quantify these relationships. The permeability of concrete is directly tied to its ability to mitigate certain failure mechanisms such as corrosion and sulfate attack. The three concrete mixtures being tested by Kansas State University (KSU) vary in cementitious content as follows: (1) 100% ordinary portland cement (OPC), (2) 25% Class F fly ash (F-ash) and 75% OPC, (3) 25% Class C fly ash (C-Ash) and 75% OPC. The mixtures were also placed in three different seasons to present differing curing environmental effects. The summer slabs were cast during July and August. The fall slabs were cast in October and November. The final set of slabs were cast in March and April. Three sets of concrete specimens (lab cured, field cured and in-situ core specimens) were tested at 28, 56, 90, 180, and 360 days for strength and permeability properties. The permeability performance tests being utilized are ASTM C1202 and ASTM C642. The results have shown very desirable permeability and strength data for the mixes using blended fly ash cements. The F-ash exhibited the best high early strength and low permeability data for the summer placement season and slower strength and permeability performance at cold weather. The C-ash performed the best overall for all seasons and had the least environmental effects. The OPC performed the worst in regards to permeability and did not reach as high long term strength.

Master of Science / Department of Civil Engineering / David R. Steward / Kansas relies on groundwater for nearly 85 percent of the total water used each year, most of which is used for irrigation. Over the last 30 years, declining groundwater levels in some areas have put pressure on agricultural industries. Ongoing research on the usage of groundwater resources will be necessary to sustain agriculture. In this study, two groundwater models were developed to investigate groundwater availability and use in western Kansas. The first model, called the Saturated Thickness Model (STM), investigated how groundwater resources will change over the next century. The second model, called the Change in Water Level Model (CWLM), was used to forecast water use trends for three agricultural districts in western Kansas by relating the change in groundwater levels over time to the volume of water pumped for irrigation. To understand how these changes would affect the agricultural industry, the research investigated historical trends in reported groundwater use, corn production and cattle in feedyards. The results showed significant decreases in the modeled saturated thickness over the next 100 years in western Kansas. Modeled groundwater use matched reported groundwater use data relatively well. The model showed significant decreases in groundwater use over the next 100 years, with the largest decrease being in the southwest district. Overall, forecast water use trends were in agreement with current outlooks for each area. The results from the correlation analysis showed a negative relationship between groundwater use and irrigated corn production, indicating improved irrigation efficiency and crop species over the past 30 years. Further correlations showed the number of cattle on feed in a particular area increased with the amount of irrigated corn production in the same area. This implies the cattle feedyards tendency toward local source of grain. As groundwater resources decline, corn production will decrease, and changes in the agricultural landscape will require adaptation. Feedyards will need to find new sources of corn grain or change to a less water dependent feed. Further research is needed to determine where corn grain will be produced in the next 100 years, and how corn grain will be transported to feedyards in southwest Kansas.

Doctor of Philosophy / Department of Civil Engineering / Robert J. Peterman / This dissertation describes a testing program to evaluate the bond and splitting propensity characteristics of 5.32-mm-diameter prestressing wires. Prestressing wire reinforcement is used primarily in the production of prestressed concrete railroad ties. Twelve different 5.32-mm-diameter wires were tested in this study in order to measure bonding characteristics of the reinforcement. Establishment of the bond-slip characteristics of these reinforcement at both transfer of prestress (transfer bond) and under flexural loading (flexural bond) is necessary to enable the accurate modeling of these ties using finite elements. Transfer bond and flexure bond of various indent patterns were tested using tensioned pullouts. Specimens of various sizes with single or multiple wires were tested to determine the effects of cover and wire number on bond. Indents were machined on smooth prestressing wires to accurately compare indent geometries. Lateral expansion was tested to determine which wires have higher propensity to cause cracking or splitting. Crossties were instrumented to compare resulting lateral expansion with results found in the laboratory. The results from the testing program showed that the tensioned pullout test was able to be used to predict the transfer length of prisms made with the same reinforcement. The results also showed that the indent geometries were able to be used to predict the splitting of specimens based on the amount of slip the wire had experienced. The testing also showed the importance of concrete cover with the relation to splitting potential.

Master of Science / Department of Civil Engineering / Robert J. Peterman / With aging and deterioration of bridges, evaluation of existing conditions of their structural elements becomes vital to engineers and public officials when deciding how to repair or replace the structures. The ability to obtain necessary information on these conditions is often expensive and time consuming, especially for concrete bridges where the reinforcement is not available for inspection. Employing the surface-strain relief method could allow for accurate evaluation of aged or damaged prestressed members. The surface-strain relief method was developed to measure initial or pre-existing strains in a concrete member. It involves relieving the strain in the member and measuring the change in strain. Two methods were tested—one used a linear electrical-resistance strain gage and a three-inch-diameter diamond concrete core bit to cut around the gage, and the second method used a laser-speckle imaging device and a diamond cutting wheel to create notches perpendicular to the axis of maximum strain. Both methods measured the change in strain and related it to within 10 percent of the actual fse. The method of cutting notches and the laser-speckle imaging device provided a simpler method to be implemented in the field, while the coring method achieved a higher level of accuracy and precision.