Doctor of Philosophy / Civil Engineering / Kyle Riding / Air voids are purposefully entrained in concrete to provide freeze-thaw durability of prestressed concrete railroad ties. Durability assurance requires consistent provision of an air void system comprised of small, well-distributed bubbles in sufficient quantity for durability and a quality control method for testing tie freeze-thaw durability. Manufacturing processes at three concrete manufacturing plants were investigated in order to determine the effects of process variability on resulting concrete air void system variability. Variation in the concrete air void system and other rheological properties occurred as results of the manufacturing process and vibration. Freezing and thawing durability testing of prestressed concrete ties is currently performed by applying ASTM C666 on 3 x 4 x 11 to 16 in. specimens cut from the shoulders of concrete ties. However, excising these specimens from prestressed concrete could lead to stress changes in the sample and cracking, potentially causing false interpretations of results. Therefore, testing was undertaken to understand the effects of prestressing and sample extraction on freeze-thaw durability measured by ASTM C666. In order to assess the effects of sampling and testing procedures on freeze-thaw quality control testing results of prestressed concrete railroad ties, full ties, half ties, and 3 x 4 x 11 in. excised samples were tested. Freeze-thaw testing included determination of the optimal method to measure freeze-thaw deterioration in large sections, the effects of saw-cutting, and the presence of reinforcement. Results indicated that the Ultrasonic Pulse Velocity accurately represented deterioration in large sections. The presence of reinforcement in excised samples led to faster deterioration compared to cast ASTM C666 samples, while saw-cutting without reinforcement did not significantly affect freeze-thaw durability.

Master of Science / Department of Civil Engineering / Hani G. Melhem / The objective of this research is to use structure ambient random vibration response to detect damage level and location. The use of ambient vibration is advantageous because excitation is caused by service conditions such as normal vehicle traffic on a highway bridge, train passage on a railroad bridge, or wind loads on a tall building. This eliminates the need to apply a special impact or dynamic load, or interrupt traffic on a bridge in regular service. This research developed an approach in which free vibration of a structure is extracted from the response of this structure to a random excitation in the time domain (acceleration versus time) by averaging out the random component of the response. The result is the free vibration that includes all modes based on the sampling rate on time. Then this free vibration is transferred to the frequency domain using a Fast Fourier Transform (FFT). Variations in frequency response are a function of structural stiffness and member end-conditions. Such variations are used as a measure to identify the change in the structural dynamic properties, and ultimately detect damage. A physical model consisting of a 20 × 20 × 1670 -mm long steel square tube was used to validate this approach. The beam was tested under difference supports conditions varying from a single- to three-span continuous configuration. Random excitation was applied to the beam, and the dynamic response was measured by an accelerometer placed at various locations on the span. A numerical model was constructed in ABAQUS and the dynamic response was obtained from the finite element model subjected to similar excitation as in the physical model. Numerical results were correlated against results from the physical model, and comparison was made between the different span/support configurations. A subsequent step would be to induce damage that simulates loss of stiffness or cracking condition of the beam cross section, and that would be reflected as a change in the frequency and other dynamic properties of the structure. The approach achieved good results for a structure with a limited number of degrees of freedom. Further research is needed for structures with a larger number of degrees of freedom and structures with damage in symmetrical locations relative to the accelerometer position.

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Stacy L. Hutchinson / Precipitation impacts hydrologic structures, agricultural production, water resources management, and recreational activities, all of which significantly affect a state’s economy. Water control structure design is based on the maximum runoff rate resulting from storms with a specific return period and duration. The Rainfall Frequency Atlas (National Weather Service Technical Paper 40, 1961) (TP-40) provided statistical rainfall analysis as the basis for hydrologic structure design until the information was updated for Kansas in February 2013 (National Oceanic and Atmospheric Administration Atlas 14, volume 8) (Atlas-14). With growing concern about the effects of global climate change and predictions of more precipitation and extreme weather events, it is necessary to explore rainfall distribution patterns using the most current and complete data available. In this work, the changes in rainfall patterns were studied using the daily rainfall data from 23 stations in Kansas and 15 stations from adjacent states with daily rainfall data of 1890 through 2012. Analysis showed an increase in extreme precipitation events in Kansas with increase in magnitude from the northwest to southeast part of the state. A comparison of results of the TP-40 analysis to period 1980–2009, showed that approximately 84% of the state had an increase in short-term rainfall event magnitudes. In addition, trend analyzes on the total annual rainfall indicated a gradual increase at 21 out of 23 stations, including eight statistically significant trends. A change-point analysis detected a significant sudden change at twelve stations as early as 1940 and as recently as 1980. The increasing trend, particularly after the significant change-points, is useful in updating water management plans and can assist with agricultural production decisions such as crop selection and new plant variety development. A comparison between 10-yr, 24-hr storms from TP-40 and Atlas-14 indicated a change of -12% to 5% in Kansas. However, the number of exceedances from the 10-yr, 1-, 2-, 3-, 4-, 7-, and 10-day storms demonstrated a tendency towards more exceedances, particularly in the last five decades. Results of this study are useful for hydrologic structure design and water resources management in order to prevent accepting additional risk of failure because of the current changing climate.

Doctor of Philosophy / Department of Civil Engineering / Yacoub M. Najjar / Access to databases after the digital revolutions has become easier because large databases are progressively available. Knowledge discovery in these databases via intelligent data analysis technology is a relatively young and interdisciplinary field. In engineering applications, there is a demand for turning low-level data-based knowledge into a high-level type knowledge via the use of various data analysis methods. The main reason for this demand is that collecting and analyzing databases can be expensive and time consuming. In cases where experimental or empirical data are already available, prediction models can be used to characterize the desired engineering phenomena and/or eliminate unnecessary future experiments and their associated costs. Phenomena characterization, based on available databases, has been utilized via Artificial Neural Networks (ANNs) for more than two decades. However, there is a need to introduce new paradigms to improve the reliability of the available ANN models and optimize their predictions through a hybrid decision system. In this study, a new set of ANN modeling approaches/paradigms along with a new method to tackle partially missing data (Query method) are introduced for this purpose. The potential use of these methods via a hybrid decision making system is examined by utilizing seven available databases which are obtained from civil engineering applications. Overall, the new proposed approaches have shown notable prediction accuracy improvements on the seven databases in terms of quantified statistical accuracy measures. The proposed new methods are capable in effectively characterizing the general behavior of a specific engineering/scientific phenomenon and can be collectively used to optimize predictions with a reasonable degree of accuracy. The utilization of the proposed hybrid decision making system (HDMS) via an Excel-based environment can easily be utilized by the end user, to any available data-rich database, without the need for any excessive type of training.

Master of Science / Department of Civil Engineering / Kyle Riding / Concrete is most widely used material in construction industry, which is made up of cement, water and aggregates as its major ingredients. Aggregates contribute to 60 to 75 % of the total volume of concrete. The aggregates play a key role in the concrete durability. The U.S Midwest has many aggregates that can show distress in the field under freezing and thawing conditions. The objective of this research was to determine if the Test Method for the Resistance of Unconfined Coarse Aggregate to Freezing and Thawing, method CSA A23.2-24A, could be used to differentiate good from poor performing aggregates in concrete. In this study fifty one KDOT aggregates (including twelve ledge and thirty nine production samples) were tested for freeze thaw resistance using CSA A23.2-24A test method and were compared to the results of the standard KDOT aggregate qualification tests. In addition to performing the CSA test method using a 3% sodium chloride solution, a subset of the aggregates were tested using either a 3% magnesium chloride or calcium chloride solution to determine the effects of the salt type on the aggregate performance. No correlation was found between the CSA A23.2-24A test method results and the standard KDOT aggregate qualification tests. The results also indicated that the mass loss in the CSA A23.2-24A was similar for the aggregate sizes tested. The use of alternate salt solutions like MgCl2 and CaCl2 resulted in increased freeze thaw mass loss in limestone aggregates.

Master of Science / Department of Civil Engineering / Stacey Kulesza / In Kansas, mechanically stabilized earth (MSE) retaining walls are typically backfilled with coarse aggregate. Current backfill material testing procedures used by the Kansas Department of Transportation (KDOT) utilize on-site observations for construction quality assurance and the American Association of State Highway and Transportation Officials standard T 288-12 (“Standard Method of Test for Determining Minimum Laboratory Soil Resistivity”). AASHTO T 288-12 is designed to test a soil sample’s electrical resistivity (ER) that correlates to its corrosion potential. However, the test, based on material passing through a No. 10 sieve, is inappropriate for coarse aggregate typically used by KDOT as the aggregate will be retained on a No. 10 sieve and potentially leads to over-conservative designs. However, ER imaging provides a two-dimensional (2D) profile of bulk ER of backfill material, thereby yielding more information regarding backfill uniformity compared to traditional sampling. The objective of this study was to characterize bulk ER of in-place MSE wall backfill aggregate. In this study, MSE walls selected by KDOT were tested using ER imaging during construction to determine bulk ER of the backfill. Variations within backfill ER may be a result of varying aggregate material, inclusions of fines, thoroughness of compaction, and the presence of water. ER imaging was used on five walls: four MSE walls and one gravity retaining wall that contained no reinforcement. One MSE wall contained metal reinforcement, while the other four walls contained geosynthetic. The ER imaging field method produced a 2D profile that depicted ER uniformity for bulk analysis. A post processing algorithm was generated to remove the subjective nature of the ER imaging results. The program determines the bulk ER based upon the ER imaging results. These results indicate that the laboratory analysis of AASHTO T 288-12 under-estimates the bulk ER of in-situ backfill material. Identification of a material’s bulk ER will help characterize the ER of aggregates in a complementary KDOT project. Results of this study will be used to recommend an in-situ test method for aggregate used by KDOT.

Doctor of Philosophy / Civil Engineering / Sunanda Dissanayake / Safe and efficient flow of traffic through work zones must be established by improving work zone conditions. Therefore, identifying the factors associated with the severity and the frequency of work zone crashes is important. According to current statistics from the Federal Highway Administration, 2,372 fatalities were associated with motor vehicle traffic crashes in work zones in the United States during the four years from 2010 to 2013. From 2002 to 2014, an average of 1,612 work zone crashes occurred in Kansas each year, making it a serious concern in Kansas. Objectives of this study were to analyze work zone crash characteristics, identify the factors associated with crash severity and frequency, and to identify recommendations to improve work zone safety. Work zone crashes in Kansas from 2010 to 2013 were used to develop crash severity models. Ordered probit regression was used to model the crash severities for daytime, nighttime, multi-vehicle and single-vehicle work zone crashes and for work zones crashes in general. Based on severity models, drivers from 26 to 65 years of age were associated with high crash severities during daytime work zone crashes and driver age was not found significant in nighttime work zone crashes. Use of safety equipment was related to reduced crash severities regardless of the time of the crash. Negative binomial regression was used to model the work zone crash frequency using work zones functioned in Kansas in 2013 and 2014. According to results, increased average daily traffic (AADT) was related to higher number of work zone crashes and work zones in operation at nighttime were related to reduced number of work zone crashes. Findings of this study were used to provide general countermeasure ideas for improving safety of work zones.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Chih-Hang John Wu / Quality is a result of product design and production control. Product design must maximize the ability to function across variations in production and environment. Production control must monitor and maintain the key design characteristics necessary for the intended function. Failure to do so results in premature part failure and increased costs. This has occurred in the production of modern cross ties. By designing quality into the product and production process, performance is maximized. This research presents a methodology for incorporating quality into the product design and production process. For product design, a relationship between product performance and design parameters is established by modeling techniques. These models provide a means to redesign the product to maximize performance and to understand the sensitivity of the design to fluctuation in production and environment. These models also establish the key design parameters that are critical for sustaining quality. For production, a method of monitoring the key design parameters is presented that provides an affordable means of automated inspection. Automated inspection removes operator error from the inspection process and allows for greater sampling rates to be achieved. The methodology presented allows for a potential of 100% inspection to be achieved with minimal impact to production costs. The research is applied to the analysis and quality control of pre-stressing steel reinforcement for concrete cross-ties. This application provides an opportunity to test and verify the research findings on a real world problem. Novel automated 3D spatial analysis algorithms are presented. This research furthers the state of the art of performing Geometrical Dimensioning and Tolerancing (GD&T). A cost effective method of non-contact surface profiling was developed with high resolution and high density surface profiles. The combined research findings present a methodology of achieving quality by design.

Master of Science / Department of Geology / Abdelmoneam Raef / Geotechnical site characteristics are a function of the subsurface elastic moduli and the geologic structures. This study integrates borehole, surface and laboratory measurements for a geotechnical investigation that is focused on investigating shear-wave velocity (Vs) variation and its implication to geotechnical aspects of the Ogden test site in eastern Kansas. The area has a potential of seismicity due to the seismic zone associated with the Nemaha formation where earthquakes pose a moderate hazard. This study is in response to recent design standards for bridge structures require integrating comprehensive geotechnical site characterization. Furthermore, evaluation of dynamic soil properties is important for proper seismic response analysis and soil modeling programs. In this study, near surface geophysical site characterization in the form of 2D shear-wave velocity (Vs) structure that is compared with laboratory measurements of elastic moduli and earth properties at simulated in situ overburden pressure conditions and synergy with downhole Acoustic Televiewer time and amplitude logs, proved very robust “validated” workflow in site characterization for geotechnical purposes. An important component of a geotechnical site characterization is the evaluation of in-situ shear modulus, Poisson’s ratio and reliable and accurate elastic modulus ([lambda]) and shear modulus ([mu]) estimates are important in a good geotechnical site characterization. The geophysical site characterization, undertaken in this study, will complement and help in extrapolating drilling and core-based properties deduced by the geotechnical engineers interested at the test site.

Master of Science / Department of Civil Engineering / Hayder A. Rasheed / Throughout history natural fiber was used as one of the main building materials all over the world. Because the use of such materials has decreased in the last century, not much research has been conducted to investigate their performance as a reinforcing material in cement and concrete. In order to investigate one of the most common natural fibers, wheat fibers, as a reinforcing material, 156 mortar specimens and 99 concrete specimens were tested. The specimens were tested in either uniaxial compression or flexure. The uniaxial compression test included 2 in (50.8 mm) mortar cubes and 4x8 in (101.6 x 203.2 mm) concrete cylinders. As for the flexure test, they were either 40x40x160 mm cementitious matrix prisms or 6x6x21 in (152.4x152.4x533.4 mm) concrete prisms. Several wheat fibers percentages were studied and compared with polypropylene fiber as a benchmarking alternative. The average increase in the uniaxial compression strength for cementitious matrix cubes reinforced with 0.5% long wheat fiber exceeded that of their counterparts reinforced with polypropylene fiber by 15%. Whereas for concrete cylinders reinforced with 0.75% long wheat fiber, their strength exceeded that of their counterparts reinforced with polypropylene fiber by 5% and that of the control by 7%. The flexural strength of cementitious matrix prisms reinforced with 0.75% long wheat fiber exceeded that of their counterparts reinforced with polypropylene fiber by 27%. Meanwhile, concrete prisms reinforced with both long wheat fiber and polypropylene fiber showed deterioration in strength of up to 17%. Finally, ABAQUS models were developed for concrete cylinders and prisms to simulate the effect of inclusion of the wheat fibers.