Civil and Environmental Engineering electronic theses and dissertations (MU)
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The items in this collection are the theses and dissertations written by students of the Department of Civil and Environmental Engineering. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item The fate of polyfluoroalkyl substances (precursors) in drinking-water treatment processes(University of Missouri--Columbia, 2025) Sun, Runze; Xiao, FengPer- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals whose widespread use in consumer and industrial products, including aqueous film-forming foams (AFFFs), has led to extensive environmental contamination and poses considerable risks to human health. Conventional drinking water treatment systems often inadequately remove PFAS. Moreover, these processes can transform polyfluoroalkyl compounds (or precursors) into highly stable perfluoroalkyl acids (PFAAs), a critical transformation pathway historically overlooked in drinking water treatment, which creates more persistent compounds often subject to stricter regulation. While separation technologies like granular activated carbon (GAC) are commonly employed, significant challenges remain, including variable adsorption efficiencies in complex water matrices, the management of spent media, and the potential for forming hazardous products of incomplete destruction (PIDs) during thermal regeneration of PFAS-landed media. This dissertation aims to address critical knowledge gaps regarding the transformation, treatability, and ultimate destruction of precursors and perfluorinated counterparts during drinking-water treatment (coagulation, flocculation, disinfection, GAC adsorption) and the thermal regeneration and reactivation of spent GAC. The results will provide valuable insights into optimizing PFAS removal strategies, improving the sustainability of water treatment processes, and minimizing the formation of hazardous byproducts. Within conventional drinking water treatment, coagulation demonstrated limited effectiveness (4%-28%) for cationic and zwitterionic precursors in AFFFs, whereas anionic PFAS exhibited higher removal rates (up to 54%). Flocculation subsequently improved overall removal efficiency to approximately 44%. Chlorine disinfection investigations revealed complex mechanisms where AFFF-derived polyfluoroalkyl substances (precursors) transformed into more stable perfluorinated acids, predominantly via chlorine attacks on susceptible -NH- functional groups, resulting in persistent perfluorinated by-products. Chlorination degraded all tested precursors effectively; however, reaction rate constants significantly decreased (over 50%) due to interference from dissolved organic matter (DOM). Reactivity varied notably among PFAS, with nitrogen-containing and longer-chain compounds undergoing more extensive degradation. These findings provide the first comprehensive assessment of conventional water treatment processes for AFFF-contaminated water samples. Thermal regeneration analyses demonstrated effective regeneration of PFAS-laden activated carbon using conventional coil heaters (muffle or tube furnaces) or novel induction heating methods, in both air and nitrogen atmospheres. Spectroscopic analyses indicated that PFAS thermal degradation initiated via bond cleavage, forming perfluoroalkyl radicals and subsequent organofluorine PIDs (e.g., perfluoroalkenes). Critically, the generation of tetrafluoromethane (CF4) was not detected, but carbonyl fluoride (CF2O) formed exclusively under specific conditions from potassium perfluorooctanesulfonate. Incorporating additives like GAC and noble metal catalysts significantly enhanced PFAS mineralization and minimized PID formation. Overall, this dissertation advances the mechanistic understanding of precursor transformation, adsorption behaviors, and thermal degradation processes in engineered systems. These findings support optimized and sustainable treatment strategies, providing critical insights for comprehensive environmental management practices and regulatory frameworks aimed at mitigating PFAS-associated risks.Item Dynamic analysis of cold-formed steel roof truss systems under blast loads(University of Missouri--Columbia, 2025) Helal, Zinab; Salim, Hani[EMBARGOED UNTIL 05/01/2027] Cold-formed steel (CFS) roof truss systems are widely used in structural applications due to their high strength-to-weight ratio and construction efficiency. However, such systems are not explicitly addressed in existing blast-resistant design standards such as the Unified Facilities Criteria (UFC), and their complex failure mechanisms, ranging from local buckling to connection rupture, pose unique challenges under extreme dynamic loading. This dissertation presents a comprehensive investigation into the dynamic response of full-scale CFS roof trusses subjected to blast loading, combining experimental testing, finite element (FE) modeling, and analytical methods. A validated three-dimensional transient dynamic FE model, developed in ANSYS Workbench 2023, accurately predicted peak deflection with a deviation of less than 2% from full-scale experimental field data. Parametric studies were conducted to examine the influence of truss height, chord thickness and widths, web thickness, yield strength, and roof slope across symmetric, asymmetric, and inclined truss configurations. Key findings showed that increasing yield strength and chord thickness reduced peak deflection by up to 43% and 64%, respectively, with diminishing improvements beyond 600 MPa and 1.85 mm. Asymmetric trusses exhibited increased torsional deformation and local instability. Inclined roof trusses with a 14° slope experienced over 85% higher deflections compared to flat trusses, due to increased reflected pressures and complex dynamic behavior. An analytical framework for evaluating the blast response of Cold-Formed Steel (CFS) roof trusses through the development of a static resistance function and a Single-Degree-of-Freedom (SDOF) dynamic model has been developed. The analytical model incorporates material properties, geometric nonlinearity, and boundary conditions to capture the nonlinear resistance of CFS trusses, demonstrating strong correlation with experimental results, with deviations typically within 5--10%. The SDOF approach was successfully validated against experimental and finite element (FE) analysis results, demonstrating its effectiveness in predicting dynamic structural response under blast loads. Furthermore, the limitations of current blast load estimation methods were evaluated. The ASCE procedure overestimated response by up to 214.6%, whereas the proposed Calculated Pressure Wave (CPW) method achieved improved accuracy with a maximum error of 41%. These findings confirm the need for refined blast load modeling and structural response prediction in CFS systems. Overall, this work delivers validated modeling strategies, analytical tools, and design recommendations for CFS trusses under blast loads. It supports the advancement of blast-resistant design practices and provides a strong foundation for updating UFC and ASCE guidelines to better reflect the behavior of CFS roof systems in extreme dynamic environments.Item Dynamic response of curved laminated glass panels(University of Missouri--Columbia, 2025) Elgholmy, Lamies; Salim, Hani[EMBARGOED UNTIL 05/01/2027] Extreme events, such as blasts, pose a severe threat to a building's structural integrity. The building envelope serves as the primary defense against external explosions, with blast hazards continuing to pose a significant threat to occupant safety. To address such challenges, the development of blast-resistant materials and structures remains a critical area of research and innovation. Laminated glass (LG) plays a crucial role in enhancing the blast resistance of structures. It consists of multiple layers of glass bonded with a polymeric interlayer, which effectively holds glass fragments together and prevents hazardous spall during blast loading. While significant research has focused on the dynamic response of flat laminated glass panels, there is a notable gap in understanding the dynamic behavior of curved laminated glass (CLG) panels, particularly under blast loads. This dissertation investigates the dynamic response of CLG windows, which are critical in applications where safety against blast loads is paramount. The primary goal of this research is to bridge the knowledge gap by comprehensively studying the nonlinear deformation and failure mechanisms of CLG windows under various blast load conditions. This study involves performing quasistatic tests on full-scale CLG panels using a water chamber to simulate the static load conditions, coupled with dynamic tests using a shock tube to replicate blast load scenarios. These experiments aim to assess the resistance and identify the predominant failure modes of CLG panels under diverse loading conditions, providing critical data on the behavior of these panels when subjected to real-world blast impacts. An advanced numerical model will be developed using ANSYS AUTODYN to predict the dynamic response of CLG panels. This model will be validated against the experimental results to ensure its accuracy in simulating the deformation, damage, and failure mechanisms of CLG windows subjected to blast loads. The validated model will serve as a robust tool for further studies and design optimizations. Utilizing the validated numerical model, this research will conduct an extensive parametric study to explore the influence of key design parameters on the performance of CLG windows under dynamic conditions. This study will evaluate factors such as the degree of curvature, type of glass and interlayer, and thickness of glass and interlayers, multi-layer CLG, asymmetric LG, layup configurations, and layup orientations, which are critical in optimizing the design and enhancing the performance of CLG panels. The findings from this comprehensive study are expected to significantly advance our understanding of the nonlinear deformation and failure modes of CLG panels. This will contribute to the development of improved design guidelines and standards for the use of curved laminated glass in structures that are subjected to dynamic loads, thereby enhancing their safety and resilience. This dissertation aims not only to fill the existing research gap but also to pave the way for future innovations in the field of blast-resistant architectural design.Item Development of novel chitosan-based ion-imprinted polymers for selective recovery of rare earth elements from mine waste(University of Missouri--Columbia, 2025) Earwood, John; Deng, Baolin[EMBARGOED UNTIL 05/01/2026] This dissertation investigates the development of alkali/urea dissolved chitosan hydrogels (AUCH) for the selective recovery of critical rare earth elements (REEs) from mine waste. Through a systematic approach advancing from single-element to multi-element systems, the research demonstrates exceptional selectivity, high adsorption capacity, and robust performance across diverse environmental conditions. First, the AUCH platform was established by optimizing crosslinking strategies with glutaraldehyde (AUCH-G) and 1,2,7,8-diepoxyoctane (AUCH-D), achieving neodymium adsorption capacities up to 174.7 mg/g with maintained selectivity across pH 2-10. The research then expanded to target heavy REEs, with AUCH-D achieving maximal capacities of 162.53 mg/g for Tb(III) and 132.05 mg/g for Dy(III), revealing differences in adsorption mechanisms through thermodynamic and kinetic analyses. These investigations demonstrated that despite more favorable thermodynamic parameters for Dy(III), Tb(III) exhibited superior adsorption performance, highlighting the complex interplay between ionic radius, coordination geometry, and entropy-driven binding. Further advancing the technology, the study demonstrated ratio-controlled extraction of adjacent lanthanides through dualtemplate imprinting, maintaining specific Nd ratios (1:1, 2:1, and 4:1) that mirror commercially relevant didymium compositions. Thermodynamic analyses revealed consistently lower energy requirements for Nd(III) binding compared to Pr(III), providing mechanistic insights into selective adsorption. Finally, optimal regeneration protocols were established through comparative evaluation of mineral acids and chelating agents, where 0.05M EDTA achieved optimal balance between elution efficiency and material preservation, with degradation rather than binding site saturation identified as the primary mechanism of capacity loss. Collectively, this work advances fundamental understanding of selective REE binding mechanisms while demonstrating practical applications for critical materials recovery from secondary resources.Item Effects of acoustic wave velocities in bridge steels on ultrasonic testing(University of Missouri--Columbia, 2025) Agbede, Joshua Olaoluwa; Washer, Glenn[EMBARGOED UNTIL 05/01/2026] Ultrasonic testing (UT) Is commonly used in the manufacturing of steel bridges to assure weld quality by identifying discontinuities that are either acceptable or rejectable. However, UT accuracy is influenced by the differences in acoustic properties between the material under inspection and the calibration reference standard. Variations in shear wave velocity can change the refracted angle and amplitude of ultrasonic waves, resulting in misclassification or missed indications. This research investigates acoustic anisotropy and its effects in a variety of modern bridge steels, including as-rolled, controlled-rolled, thermomechanically controlled processed (TMCP), quenched and tempered (QT), CR-50 stainless steel, and additively manufactured (AM) materials. Velocity measurements in several propagation directions were carried out using pulse-echo ultrasonic methods, and the second-order elastic constants (Cij) were calculated by analyzing twelve wave modes and observed densities. The findings reveal that elastic and acoustic properties vary greatly depending on manufacturing process and orientation relative to the rolling direction, with anisotropy affecting both wave velocity and signal amplitude. The study also examines the implications of beam splitting in anisotropic materials and how it affects shear wave sensitivity during weld inspection. The findings highlight the need of accounting for materialspecific acoustic properties in UT calibration, as well as providing input data for finite element modeling and simulation in ultrasonic inspection software like CIVA.