Master of Science / Department of Civil Engineering / David G. Chandler / Infiltration capacity influences the ability of a soil to absorb and transmit water through macropores and micropores of the soil structure. Infiltration is primarily influenced by the soil type, which is dependent on a number of factors including parent material, climate, biological activity, and topography. Spatial controls of land use, land cover, soil texture, slope position, slope gradient and slope aspect are a few of the variables influencing infiltration capacity within a uniform soil type. The goals of the thesis are to (1) quantify the spatial distribution of soil hydraulic properties at the surface of a hillslope using one measurement method - the automated mini-disk tension infiltrometer - and several analysis methods, (2) determine the dependence of depth on soil hydraulic properties using two measurement methods, and (3) compare the results of the investigation with information from the soil survey and soil investigations. First, automated mini-disk infiltrometers were used to determine soil hydraulic properties at ten sites along a hillslope in Konza Prairie Natural Research Area. Several analysis methods were used to extract hydraulic conductivity and sorptivity values from the infiltration data. Next, large intact soil cores were extracted from three selected sites at the same hillslope and analyzed at six depths using a large disk infiltrometer. Finally, the six segments of the large soil cores were analyzed using the same methods as the field measurements with the mini-disk infiltrometers. The results of the field investigation at the ten sites show a variability of soil hydraulic properties over an assumed homogeneous landscape. The values of hydraulic conductivity and sorptivity are dependent on the method of analysis. An empirically based approach produced more realistic values than a physically based approach. The results of the laboratory investigation of the three extracted soil cores also show a dependence of method of analysis and measurement. In addition, the results show a complex relationship among landscape position, depth, and soil structure. Finally, while soil surveys and soil descriptions can provide detailed information on soil properties, an infiltration investigation at a detailed spatial scale provides quantitative values for soil hydraulic properties.

Master of Science / Department of Civil Engineering / Hayder A. Rasheed / Fiber reinforced polymer has recently become a popular replacement for steel rebar, used to reinforce concrete. Therefore much research is taking place to help develop and propose methods for best approximating the response of FRP reinforced members, to make them comparable to steel reinforced members. With this popularity comes multiple approaches to FRP deflection calculations. However, this study is significant, because it investigates the cracking moment equation adopted by ACI 318, in conjunction with state of the art deflection calculation methods. Specifically this research compares four deflection calculation methods. The first approach is proposed by Bischoff and implemented by ACI 440 in its latest revision. The second deflection calculation method is proposed by Rasheed et al. The third calculation is also suggested by Bischoff, as it is specific to four point bending. The fourth calculation method is proposed by this specific research and seeks to find a median between both the Bischoff and Rasheed equations. This fourth technique will be referred to as the Rasheed-Jacobs method, proposed to create a more conservative and relevant method for investigating the effect of cracking moment on the deflection calculations. This research was done with the help of Dr. Shawn Gross, and the database he had previously built through his investigation on FRP reinforced beams. Gross’s database shows results for 106 samples tested using the actual experimental cracking moment as well as the ultimate moment capacity values. Of these 106 samples, 56 independent samples were used to investigate three different moment levels of 0.333Mn, 0.400Mn, and 0.467Mn. From this research, Gross’s database was used to calculate the cracking moment of FRP reinforced beams based on ACI 318-08. A program was developed that uses the Gross database samples to calculate the cracking moment and deflection with the Rasheed, Bischoff, and Bischoff2 models as well as the new Rasheed-Jacobs model. This program calculates the Rasheed-Jacobs results, and then graphs the findings against the deflection values from the Rasheed, Bischoff, Bischoff2 models. These graphs showed very similar patterns amongst all four models, with the Rasheed-Jacobs results mainly falling on the more conservative side. However, when looking at the predicted deflection verse the Gross experimental deflection, the best results came from the 0.467Mn moment level, which shows consistent correlation while the lower moment levels are being less predictable using the cracking moment based on the ACI equation. It can reasonably be said that the 0.467Mn shows the best correlation between the four methods and the experimental results, because it is farther away from the actual nominal cracking moment of the FRP reinforced concrete beams.

Master of Science / Department of Civil Engineering / Robert J. Peterman / This thesis presents results from transfer length measurements on prestressed concrete railroad ties. Results are shown from the four main producers of concrete ties in the United States. Six prestressed concrete tie plants were visited by the research team to measure transfer length on ties with various mix designs and prestressing reinforcement. After all plants had been visited, a total of nine concrete-mix designs and 10 reinforcement variations were tested. Overall, 220 transfer length measurements were conducted on prestressed concrete railroad ties during the duration of this research project. This was the first coordinated effort to measure transfer lengths in concrete railroad ties ever conducted in the industry. Concrete strains were monitored using the standard Whittemore gage, as well as a non-contact procedure called laser-speckle imaging (LSI). This method to measure transfer lengths has been developed at Kansas State University (KSU). Ties measured using the Whittemore gage were sent back to the civil engineering structural laboratory at KSU so the long-term transfer lengths could be monitored. After a certain period of time, the ties were load-tested according to the American Railway Engineering and Maintenance-of-Way Association (AREMA) loading specifications of the rail-seat positive moment test.

Master of Science / Department of Civil Engineering / Mustaque A. Hossain / Over the lifetime of an asphalt concrete (AC) pavement, the roadway requires periodic resurfacing and rehabilitation to provide acceptable performance. The most popular resurfacing method is an asphalt overlay over the existing roadway. In the design of asphalt overlays, the thickness is related to the structural capacity of the existing pavement. As the layers are overlaid, their structural characteristics change due to aging of asphalt. However, currently there is no method to determine the effect of aging on the structural capacity of an existing pavement. This study examined structural characteristics of six test roadways in Kansas using three different test methods: Falling Weight Deflectometer (FWD), Portable Seismic Property Analyzer (PSPA), and Indirect Tensile (IDT) test. The results were analyzed to determine how the modulus of an AC pavement layer changes over time. The results indicate that as the AC pavement ages, its modulus decreases due to pavement deterioration, especially stripping. Two test roadways that showed little signs of stripping had a minimal reduction or even an increase in AC moduli. Thus, the stripping issue needs to be addressed to ensure longevity of AC pavements. While the correlation between test methods studied was mostly consistent for each roadway, no universal correlation was found. The structural coefficient of each AC layer was determined based on the resilient modulus of the layer. It was found the structural layer coefficients do not typically decrease with age at the same rate, and the rate of decrease is a function of the distresses observed.

Doctor of Philosophy / Department of Civil Engineering / Hayder Rasheed / The analysis of concrete columns using unconfined concrete models is a well established practice. On the other hand, prediction of the actual ultimate capacity of confined concrete columns requires specialized nonlinear analysis. Modern codes and standards are introducing the need to perform extreme event analysis. There has been a number of studies that focused on the analysis and testing of concentric columns or cylinders. This case has the highest confinement utilization since the entire section is under confined compression. On the other hand, the augmentation of compressive strength and ductility due to full axial confinement is not applicable to pure bending and combined bending and axial load cases simply because the area of effective confined concrete in compression is reduced. The higher eccentricity causes smaller confined concrete region in compression yielding smaller increase in strength and ductility of concrete. Accordingly, the ultimate confined strength is gradually reduced from the fully confined value fcc (at zero eccentricity) to the unconfined value f’c (at infinite eccentricity) as a function of the compression area to total area ratio. The higher the eccentricity the smaller the confined concrete compression zone. This paradigm is used to implement adaptive eccentric model utilizing the well known Mander Model and Lam and Teng Model. Generalization of the moment of area approach is utilized based on proportional loading, finite layer procedure and the secant stiffness approach, in an iterative incremental numerical model to achieve equilibrium points of P- and M- response up to failure. This numerical analysis is adaptod to asses the confining effect in circular cross sectional columns confined with FRP and conventional lateral steel together; concrete filled steel tube (CFST) circular columns and rectangular columns confined with conventional lateral steel. This model is validated against experimental data found in literature. The comparison shows good correlation. Finally computer software is developed based on the non-linear numerical analysis. The software is equipped with an elegant graphics interface that assimilates input data, detail drawings, capacity diagrams and demand point mapping in a single sheet. Options for preliminary design, section and reinforcement selection are seamlessly integrated as well. The software generates 2D interaction diagrams for circular columns, 3D failure surface for rectangular columns and allows the user to determine the 2D interaction diagrams for any angle  between the x-axis and the resultant moment. Improvements to KDOT Bridge Design Manual using this software with reference to AASHTO LRFD are made. This study is limited to stub columns.

Master of Science / Department of Civil Engineering / Hayder A. Rasheed / Damage detection and structural health monitoring are topics that have been receiving increased attention from researchers around the world. A structure can accumulate damage during its service life, which in turn can impair the structure’s safety. Currently, visual inspection is performed by experienced personnel in order to evaluate damage in structures. This approach is affected by the constraints of time and availability of qualified personnel. This study aims to facilitate damage evaluation and detection in concrete bridge girders without the need for visual inspection while minimizing field measurements. Simply-supported beams with different geometric, material and cracking parameters (cracks’ depth, width and location) were modeled in three phases using Abaqus finite element analysis software in order to obtain stiffness values at specified nodes. In the first two phases, beams were modeled using beam elements. Phase I included beams with a single crack, while phase II included beams with up to two cracks. For phase III, beams with a single crack were modeled using plane stress elements. The resulting damage databases from the three phases were then used to train two types of Artificial Neural Networks (ANNs). The first network type (ANNf) solves the forward problem of providing a health index parameter based on the predicted stiffness values. The second network type (ANNi) solves the inverse problem of predicting the most probable cracking pattern, where a unique analytical solution is not attainable. In phase I, beams with 3, 5, 7 and 9 stiffness nodes and a single crack were modeled. For the forward problem, ANNIf had the geometric, material and cracking parameters as inputs and stiffness values as outputs. This network provided excellent prediction accuracy measures (R2 > 99%). For the inverse problem, ANNIi had the geometric and material parameters as well as stiffness values as inputs and the cracking parameters as outputs. Better prediction accuracy measures were achieved when more stiffness nodes were utilized in the ANN modeling process. It was also observed that decreasing the number of required outputs immensely improved the quality of predictions provided by the ANN. This network provided less accurate predictions (R2 = 68%) compared to ANNIf, however, ANNIi still provided reasonable results, considering the non-uniqueness of this problem’s solution. In phase II, beams with 9 stiffness nodes and two cracks were modeled following the same procedure. ANNIIf provided excellent results (R2 > 99%) while ANNIIi had less accurate (R2 = 65%) but still reasonable predictions. Finally, in phase III, simple span beams with 3, 5, 7 and 9 stiffness nodes and a single crack were modeled using plane stress elements. ANNIIIf (R2 > 99%) provided excellent results while ANNIIIi had less accurate (R2 = 65%) but still reasonable predictions. Predictions in this phase were very accurate for the crack depth and location parameters (R2 = 97% and 99%, respectively). Further inspection showed that ANNIIIi provided more accurate predictions when compared with ANNIi. Overall, the obtained results were reasonable and showed good agreement with the actual values. This indicates that using ANNs is an excellent approach to damage evaluation, and a viable approach to obtain the, analytically unattainable, solution of the inverse damage detection problem.

Doctor of Philosophy / Department of Civil Engineering / Kyle A. Riding / The cement industry is an important component in the quest to reduce global greenhouse gas emissions because of vast amounts of cement used annually. Incorporating supplementary cementitious materials (SCMs) into concrete is one alternative to reduce cement production and thereby reduce greenhouse gas emissions. This study investigated three types of agricultural residues, namely corn stover, wheat straw, and rice straw, in addition to bioethanol byproducts as potential resources for SCM production for concrete applications. Pretreatments, commonly used in bioethanol production, were used to improve pozzolanic reactivity of corn stover ash (CSA), wheat straw ash (WSA), and rice straw ash (RSA) in cementitious systems. In the first part of this research, the impact of distilled water and dilute hydrochloric acid pretreatments on pozzolanic reactivity of WSA, RSA, and CSA were studied. Results showed that pretreatments, particularly dilute acid, improved pozzolanic properties of CSA, WSA, and RSA by removing potassium and phosphorous from the biomass prior to ashing. In addition, WSA and RSA were shown to have similar pozzolanic reactivity to that of silica fume. In the second part of this study, suitability of high lignin residue (HLR), a bioethanol byproduct, for SCM production was investigated. It was shown that burning high lignin residue produces HLR ash that is very reactive in cementitious materials and can be used as a reactive SCM in concrete. The impact of each step in the production of bioethanol on the quality of bioethanol byproduct for subsequent burning and use in concrete was also studied. Sodium hydroxide and sulfuric acid pretreatments and enzymatic hydrolysis were used. Results revealed that sodium hydroxide pretreatment of the biomass have negative impact on biomass ash properties for concrete use because sodium hydroxide pretreatment did not remove phosphorous and other crystalline phases out of the biomass. However, sulfuric acid pretreatment of biomass greatly improved ash properties. It was also shown that enzymatic hydrolysis could have beneficial impact on ash properties because, during enzymatic hydrolysis, some phosphorous was leached out of the biomass.

Master of Science / Department of Civil Engineering / Mustaque Hossain / Reclaimed Asphalt Pavement (RAP) is a useful alternative to virgin aggregates in hot-mix asphalt (HMA) as it reduces cost, conserves energy, and enables reuse of existing asphalt pavement. However, use of higher percentage of RAP sometimes leads to drier mixes that are often susceptible to early cracking. In this study, cracking resistance of Superpave mixtures with varying asphalt and RAP contents were investigated. HMA specimens were prepared based on Superpave mix design criteria for 12.5-mm (1/2-inch) nominal maximum aggregate size (NMAS). Specimens were compacted using the Superpave gyratory compactor. Static and repeated semi-circular bending (SCB) tests and Texas overlay tests (OT) (TEX-248-F) were performed in order to evaluate cracking resistance of Superpave mixtures containing three different asphalt contents (5.2%, 4.9%, and 4.6%) and three RAP percentages (20%, 30%, and 40%) from two distinct sources. Results from both crack tests showed that, with decreased asphalt content, cracking propensity increases. In general, higher percentage of RAP decreases cracking resistance. Statistical analysis of the results indicated a strong positive correlation between the asphalt film thickness and the number of load cycles before failure. Comparison of mean test results suggested that the Texas overlay test could do better evaluation of cracking resistance than the R-SCB test. This study was limited to mixtures with two sources of RAP. Because of such limitations and conflicting results from these RAP sources, a general conclusion regarding the minimum binder and maximum RAP contents without compromising cracking resistance could not be made. However, separate conclusions were drawn depending upon the characteristics of the RAP source.

Master of Science / Department of Civil Engineering / Kyle A. Riding / Air void clustering around coarse aggregate in concrete has been identified as a potential source of low strengths in concrete mixes by several Departments of Transportation around the country. Research was carried out to (1) develop a quantitative measure of air void clustering around aggregates, (2) investigate whether air void clustering can be reproduced in a laboratory environment, (3) determine if air void clustering can blamed for lower compressive strengths in concrete mixes, (4) and identify potential factors that may cause clustering. Five types of coarse aggregate and five different air entraining agents were included in the laboratory study to see if aggregate type or chemical composition of air entraining agent directly relates to air void clustering. A total of 65 mixes were made, implementing the frequently used technique of retempering that has been previously associated with air void clustering around aggregates. Compressive strength specimens as well as samples for hardened void analysis were made. Compressive strength at 7 and 28 days was determined and the automated hardened void analysis (including a new method of clustering evaluation) was performed on all samples. It was found that it is possible to reproduce air void clustering in laboratory conditions. However, the results have shown that retempering does not always cause air void clustering. It was also observed that air void clustering is not responsible for a decrease in compressive strength of retempered concrete as neither aggregate type nor chemical composition of air entraining agent had a significant impact on severity of void clustering around coarse aggregate particles. It was also found that the total air content and an inhomogeneous microstructure and not air void clustering were responsible for lower strengths.

Master of Science / Department of Civil Engineering / Sunanda Dissanayake / Although extensive research has been conducted on urban freeway capacity estimation methods, minimal research has been carried out for rural highway sections, especially sections within work zones. This study filled that void for rural highways in Kansas. This study estimated capacity of rural highway work zones in Kansas. Six work zone locations were selected. An average of six days’ worth of field data was collected, from mid-October 2013 to late November 2013, at each of these work zone sites. Two capacity estimation methods were utilized, including the Maximum Observed 15-minute Flow Rate Method and the Platooning Method divided into 15-minute intervals. The Maximum Observed 15-minute Flow Rate Method provided an average capacity of 1469 passenger cars per hour per lane (pcphpl) with a standard deviation of 141 pcphpl, while the Platooning Method provided a maximum average capacity of 1195 pcphpl and a standard deviation of 28 pcphpl. Based on observed data and analysis carried out in this study, the recommended capacity to be used is 1500 pcphpl when designing work zones for rural highways in Kansas. This research provides the proposed standard value of rural highway work zone capacities so engineers and city planners can effectively mitigate congestion that would have otherwise occurred due to impeding construction/maintenance.