Advanced nondestructive neutron technology has been utilized to study fundamental issues in the Lost Foam Casting (LFC) process and in the mechanical behavior of infrastructure materials. Time lapsed neutron radiography combined with digital image processing was used to investigate the real-time LFC process. Behavior and characteristics of the pyrolysis front in the LFC processes were discussed. Evidence shows that neutron radiography offers new insights into the pyrolysis front and the dynamics of the processes involved with the casting. Behavior and characteristics of the pyrolysis front and the molten metal interface in the LFC processes were revealed. The proposed approach will prove to be a powerful tool to characterize the degradation behavior of the expanded polystyrene foam during the LFC process and the interactions of liquid metal. The stress-strain relationship of particulate materials is complex, and depends on the initial state of packing, past stress history, and the applied stress path. A novel in-situ study methodology has been developed using neutron scattering technique to obtain strains both globally and locally. The significant differences between the global deformation and the local lattice strain for silica sand have been found and discussed. The measured lattice strain was at least one order of magnitude smaller than the measured related global strain. However, the actual stress within the particles could be much higher than the applied global stress. Research results from this study will be useful for developing suitable elasto-plastic constitutive models of frictional granular materials. Residual stress has a significant impact on the mechanical behavior materials. It is difficult to be measured or predicted using analytical methods, and can lead to premature failure of materials if not appropriately considered in design. Residual strains of identical steel tubular specimens after being subjected to either torsion or tension corresponding to a target equivalent strain invariant were probed using both reactor and spallation neutron sources. The lattice strains based on the hkl reflections that are reported to be both weakly and strongly affected by intergranular strain for tension stress path were investigated. The results indicate the essential difference between tension and torsion from the perspective of yield and failure criteria for materials. An innovative approach has been developed to study the complete 3-D strain tensor using the 2nd Generation Neutron Residual Stress Facility at Oak Ridge National Laboratory. A procedure was also established to understand the mechanism and to analyze the errors of the calculated strain tensor. This newly developed approach makes it possible to study the strain/stress state in materials under complex conditions.

The purpose of this study was to examine the load experienced by a steel blast cubicle from a surface blast test. An important objective was to determine the blast load experienced at different standoff distances and the blast resistance capability of the blast cubicle. Three cubicles with standoff distances of 20, 25, and 30ft respectively were simultaneously subjected to a 50lb TNT explosive. The manual Structures to Resist the Effects of Accidental Explosions, Army TM 5-1300 conservatively predicted the blast pressure loadings obtained from the pressure transducers mounted on the cubicles. Data collected from accelerometers was compared to results from the analysis program SDOF. The cubicle walls exhibited elastic behavior without any visible permanent deformation. The wall facing the blast was found to experience the greatest loading and was the critical member. The roof, however, experienced substantial deformation. As the standoff distance from the blast increased the pressure loading experienced by the cubicles decreased. The cubicle closest to the blast was likely close to its limit. Thus the structural design of the blast cubicle was efficient and economical without waste of construction material.

The objective of this research study is to analyze the preliminary structural behavior of a pile framed tie back retaining wall concept created by the Tennessee Department of Transportation (TDOT). Instrumentation is used to measure the forces and moments on the steel piles, loads on the anchors, and the pressure and displacement of the retained soil over time. Data collection for steel pile analysis consisted of the comparison of strain gage readings. Stress values were calculated from the readings and reduced down to an axial and bending force along the pile. Soil pressures that built up behind the wall were also evaluated over time by comparing gage readings and then calculating a pressure value. Preliminary results confirmed assumptions of rigid conditions of the retaining wall and negligible movement of the retained soil.

The focus of this investigation was the determination of air flotation parameters to perform solid liquid separation treatment in an activated sludge treating grease waste by promoting filamentous bacteria. The treatment was intended to achieve a pretreatment level, previous to the application of the typical activated sludge process. Generally solid liquid separation in activated sludge is performed by gravitational settling, but it is been demonstrated that the presence of an overgrowth population of filamentous microorganism in activated sludges hinder the settling properties of it. For this reason, gravitational settling may result in an inefficient treatment. Therefore, an alternative treatment has to be applied. The treated waste in this project has a density lighter than water; additionally filamentous microorganisms tend to trap fine bubbles therefore causes floating. These specific conditions make air flotation a suitable alternative technology. The ranges of minimum operation for Dissolve Air Flotation (DAF) controlling parameters (air pressure, recycle rate, rise rate, air to solid ratio, and solids recovery) were determined. For this purpose a descriptive model for the treatment was developed. The research determined that the traditional gravitational settling was not adequate for separating the biomass from the liquid phase. In contrast dissolve air flotation showed that it was possible to achieve the pretreatment level (300 mg/L in the final effluent). In the analysis the correlations between the parameters under study (air pressure and recycle rate) and the response variables (rise rate, air to solid ratio, suspended solids in the subnatant, and solids recovery) were determined. With the relationships defined, the minimum ranges for the parameters of operation of a DAF unit were determined. The results showed that in order to achieve the pretreatment level air pressure should range between 45-70 psi and the recycle rate between 30-35%. All the values for the rest of the response variables were determined to be within the ranges of the typical application of DAF, therefore the same equipment used for the typical application can be used to apply this treatment under these specific conditions.

Increased globalization has caused large increases in truck traffic on the nation’s interstate system, with much additional growth expected in the coming years. This growth has elevated interest in developing new strategies to address rising levels of truck traffic, especially in dense and congested urban areas. This thesis focuses on the evaluation of several alternative lane management configurations as they compare to the current lane configuration in search of the best fit for operational improvement. This task was performed in two ways – survey and simulation. A survey of 500 long-haul truck drivers was administered in Knoxville, Tennessee, at the crossroads of major north-south and east-west interstate highways. The dataset was evenly divided between owner-operators and truck-company employed drivers. The survey suggested the alternative truck lane management configurations and most of the respondents supported moving truck lanes to the inside travel lanes to avoid merging and lane changing cars, either through traditional truck lanes restrictions or truck only lanes. The alternative lane configurations and the current lane configuration were simulated in VISSIM. Parameters such as speed, travel time, delay, and lane change were used for evaluating the configurations during simulation. A statistical test was applied to the results of the simulations. Each configuration yielded significantly different results in most cases and a few insignificant changes in other cases. One of the configurations – the optional truck only lane configuration, stood out as the best fit for operational improvements by offering high speeds, shorter travel times, smaller delay times and greater delay cost savings, and increased highway safety. Such configuration could potentially address the challenges faced by increasing truck traffic in congested urban areas.

At the present time a large portion of America’s bridge infrastructure is aging, and in many cases approaching its design live. Therefore, there is a need for structurally sound, low-maintenance, and rapidly constructible alternatives for conventional materials. Due to this need there has been a renewed interest in structural glass fiber reinforced polymer (GFRP) products. A large portion of the US is regularly subjected to freezing temperatures and therefore the numerous gaps in our knowledge and understanding of the low-temperature response of GFRP materials need to be addressed. Although strides have been made in researching the cold climate responses of GFRP materials, a lack of comparable testing procedures and reproducible results has lead to confusion and a lack of confidence applying them. Therefore this thesis presents a detailed theoretical analysis of a structural GFRP bridge deck panel, and documents a research program that observed the effects of low-temperature and strain levels on the longitudinal modulus of GFRP samples. A series of GFRP coupon laminates were tested at 1000, 2000, and 3000 micro-strain levels at temperatures down to –31 F [-35 C]. Both biaxial and uniaxial samples subjected to 1000 micro-strain showed an increase in stiffness as the temperature was lowered, and no significant reduction in stiffness was seen when the samples were warmed back up to room temperature and retested. However samples subjected to the higher strain levels did show significant stiffness degradation when retested. The degree of degradation was noticeably larger for samples subjected to the low temperatures than for control samples that were subjected to the equivalent number of cycles at room temperature. It was also noted that the degradation due to load cycles or temperature coupled with load cycles was noticeably less for uniaxial samples than for biaxial samples.

Speed limits for large trucks have been reduced at many locales for air quality and safety reasons. To realize an improvement in air quality and safety, however, diligent enforcement and fitting punishment have to be implemented. This may put a strain on already tight resources and manpower for state and local agencies. To this end, this paper presents a license plate recognition (LPR) technology based heavy vehicle speed enforcement system that requires relatively minimal initial investment and no increase in enforcement personnel, cruisers, or pursue/pull-over activities. The efficiency of the system is achieved by catching speeding trucks in the act and then enforcing the law at weigh stations, which all trucks, with few exceptions, are required to enter. The configuration of the system for the Knoxville, TN study site is presented. Strategic placement of LPR units on I-40 and I-75 enables the speed tracking and enforcement process. Identified trucks are checked against the CVEIW national database for additional inspection, enforcement, and citation activities.

The behavior of a novel pile framed retaining wall developed by the Tennessee Department of Transportation (TDOT) is investigated using a 2D non-linear finite element (FE) analysis for. The wall design eliminates the need for a construction right of way behind the wall; thus it is ideal for urban areas. The design concept consists of vertical and battered H pile sections as the structural frame, and a concrete facing that is installed as the soil is excavated during top-down construction. Vertical tie-down anchors and a concrete cap and facing are used to counteract overturning moments. A 2-D FE analysis of the wall system was conducted to understand how the earth pressures are applied to the sloped wall, and how the loads are distributed throughout the piling frame. An increased understanding of the performance of this new system will lead to more economic pile sections and spacing under service loads. In addition, the construction sequence was modeled to investigate the non-linear response of the wall system. Parametric studies were conducted to investigate wall performance for different soil conditions, boundary conditions, wall heights, and tie-down forces. The results show that active earth pressures are adequate for design and that TDOT’s original design was conservative.

Computer simulation has become a very useful and flexible tool in the planning process of passenger facilities. By this means the probability of queues, congestion and delays can be determined, and different design concepts and operational disciplines can be considered experimentally. Within this thesis two different check-in disciplines, restricted flight system, and common system are compared. The stochastic simulation models developed to evaluate the performance of the alternative check-in systems examined the impact of 1) changes in the number of passengers boarding per flight, 2) reduction in the number of counters, and 3) different time value to the passengers. Input to the model including 1) service times, 2) passengers rate of arrivals, 3) characteristics of the passenger groups, etc. allowed for testing both alternatives. Output from the model included 1) queuing times, 2) number of persons in queue, 3) density of crowds, and 4) counter utilization. After calibrating the model with data gathered at Knoxville's airport, it was found that the common system has better performance than the restricted system. Also it was determined that the restricted system became inefficient for a large number of persons checking in per flight. Finally, by assigning monetary value to the passenger time, it was possible to select the number of counters which represented the minimum cost to the airlines, the airport operator, and the passengers.

This thesis consists of the analytical study and the experimental investigation of larger diameter strands in AASHTO Type I girders. The main purpose of this study was to verify that the 2 inch minimum spacing recommended by ACI 318-08 and AASHTO (2008) can be used for 0.7 inch diameter strands by comparing various effects in girders using 0.7 and 0.6 inch diameter strands. Based on the parametric analysis it was concluded that by using 0.7 inch strands there was a considerable saving in the material. For example, an AASHTO BT-72 with 0.6 inch strand could be replaced with AASHTO BT-54 with 0.7 inch strand for the same span capacity. In order to fully realize the benefits and to verify the adequacy of 2 inch spacing, a three dimensional finite element analysis was performed with two full-scale AASHTO Type I girders with 0.6 inch and 0.7 inch diameter strands. Only the effects due to the prestressing force at transfer were studied in the two models. The maximum principal stress and the axial stress in the concrete along the direction of the strands were determined. Based on the analytical results from the FE model it was found that the girder with the 0.7 inch diameter strand was more vulnerable to cracking at the transition zone between the bottom flange and the web. This defect could be overcome by placing the required amount of confinement reinforcement at the end zone of the girder. Based on the analytical study, two I-girder specimens, one with larger 0.7 in. strand and other with high strength 0.62 in. strand were cast. The transfer lengths of both the girders were measured and compared with the current AASHTO 2008 and ACI 318-08 equations. It was found that both strands exhibited a shorter transfer length than obtained in the equations. Based on these experimental results further studies are to be carried out for the implementation of these highly efficient strands.