Matching Items (304)
Filtering by
- All Subjects: Civil Engineering
- Member of: Theses and Dissertations
- Resource Type: Text
- Status: Published
Description
Water utilities across the United States are facing numerous challenges, such as limited funding and increasing project complexity, in constructing and upgrading their aging infrastructure. One innovative method to overcome these challenges is through the use of alternative project delivery methods (APDM), such as construction management at-risk (CMAR) and design-build (DB). Previous research has shown that APDM have the potential to deliver higher performing water infrastructure projects when compared to the traditional design-bid-build (DBB) method. However, there is a need to further examine APDM practices and develop tools that may support utilities in the delivery of their APDM water infrastructure projects. This study fills the knowledge gap by conducting several studies that may support public and private utilities in improving the delivery of their APDM water infrastructure projects. First, APDM implementation practices for water infrastructure projects are identified by assessing the state of practice, particularly during project procurement and execution. Second, DB project administration best practices are determined to support utilities seeking to add DB to their organization’s project delivery toolbox. Third, a pioneering web-based project delivery method decision-support tool was developed to aid utilities in selecting the appropriate delivery method for their water project. Finally, project-specific factors and attributes that impact project delivery performance are investigated through exploratory modeling and analysis. The study collected data on 75 completed treatment plant projects, conducted interviews with ten utilities that successfully deliver their water projects using DB, and worked closely with several industry experts through industry workshops and panels. Key findings related to water infrastructure project delivery revealed in this study included: (1) guaranteed maximum price (GMP) is the preferred compensation type for APDM projects; (2) utilities statistically having the lowest comfort level with delivering CMAR projects; (3) qualifications-based procurement is an effective DB project delivery practice; (4) the identification of 13 key project delivery method selection factors; and (5) the three highest predictors that impact unit cost performance are project complexity, project team chemistry and communication, and project size.
ContributorsFeghaly, Jeffrey (Author) / El Asmar, Mounir (Thesis advisor) / Ariaratnam, Samuel (Thesis advisor) / Bearup, Wylie (Committee member) / Arizona State University (Publisher)
Created2020
Description
Seeking to address sustainability issues associated with food waste (FW), and fat, oil, and grease (FOG) waste disposal, the City of Mesa commissioned the Biodesign Swette Center for Environmental Biotechnology (BSCEB) at Arizona State University (ASU) to study to the impact of implementing FW/FOG co-digestion at the wastewater treatment plant (WWTP). A key issue for the study was the “souring” of the anaerobic digesters (ADs), which means that the microorganism responsible for organic degradation were deactivated, causing failure of the AD. Several bench-scale reactors soured after the introduction of the FW/FOG feed streams. By comparing measurements from stable with measurements from the souring reactors, I identified two different circumstances responsible for souring events. One set of reactors soured rapidly after the introduction of FW/FOG due to the digester’s hydraulic retention times (HRT) becoming too short for stable operation. A second set of reactors soured after a long period of stability due to steady accumulation of fatty acids (FAs) that depleted bicarbonate alkalinity. FA accumulation was caused by the incomplete hydrolysis/fermentation of feedstock protein, leading to insufficient release of ammonium (NH4+). In contrast, carbohydrates were more rapidly hydrolyzed and fermented to FAs.
The most important contribution of my research is that I identified several leading indicators of souring. In all cases of souring, the accumulation of soluble chemical oxygen demand (SCOD) was an early and easily quantified indicator. A shift in effluent FA concentrations from shorter to longer species also portended souring. A reduction in the yield of methane (CH4) per mass of volatile suspended solids removed (VSSR) also identified souring conditions, but its variability prevented the methane yield from providing advanced warning to allow intervention. For the rapidly soured reactors, reduced bicarbonate alkalinity was the most useful warning sign, and an increasing ratio of SCOD to bicarbonate alkalinity was the clearest sign of souring. Because I buffered the slow-souring reactors with calcium carbonate (CaCO3), I could not rely on bicarbonate alkalinity as an indicator, which put a premium on SCOD as the early warning. I implemented two buffering regimes and demonstrated that early and consistent buffering could lead to reactor recovery.
The most important contribution of my research is that I identified several leading indicators of souring. In all cases of souring, the accumulation of soluble chemical oxygen demand (SCOD) was an early and easily quantified indicator. A shift in effluent FA concentrations from shorter to longer species also portended souring. A reduction in the yield of methane (CH4) per mass of volatile suspended solids removed (VSSR) also identified souring conditions, but its variability prevented the methane yield from providing advanced warning to allow intervention. For the rapidly soured reactors, reduced bicarbonate alkalinity was the most useful warning sign, and an increasing ratio of SCOD to bicarbonate alkalinity was the clearest sign of souring. Because I buffered the slow-souring reactors with calcium carbonate (CaCO3), I could not rely on bicarbonate alkalinity as an indicator, which put a premium on SCOD as the early warning. I implemented two buffering regimes and demonstrated that early and consistent buffering could lead to reactor recovery.
ContributorsKupferer III, Rick Anthony (Author) / Rittmann, Bruce E. (Thesis advisor) / Young, Michelle N (Committee member) / Torres, César I (Committee member) / Arizona State University (Publisher)
Created2020
Description
There has been a renewed interest to understand the degradation mechanism of concrete under radiation as many nuclear reactors are reaching their expiration date. Much of the information on the degradation mechanism of concrete under radiation comes from the experiments, which are carried out on very small specimens. With the advent of finite element analysis, a numerical predictive tool is desired that can predict the extent of damage in the nuclear concrete structure.
A mesoscale micro-structural framework is proposed in Multiphysics Object-Oriented Simulation Environment (MOOSE) finite element framework which represents the first step in this direction. As part of the framework, a coupled creep damage algorithm was developed and implemented in MOOSE. The algorithm considers creep through rheological models, while damage evolves exponentially as a function of elastic strain and creep strain. A characteristic length is introduced in the formulation such that the energy release rate associated with each element remains the same to avoid vanishing energy dissipation with mesh refinement. A creep damage parameter quantifies the effect of creep strain on the damage that was calibrated using three-point bending experiments with varying rates of loading.
The creep damage model was also validated with restrained ring shrinkage tests on cementitious materials containing compliant/stiff inclusions subjected to variable drying conditions. The simulation approach explicitly considers: (i) moisture diffusion driven differential shrinkage along the depth of the specimen (ii) viscoelastic response of aging cementitious materials (iii) isotropic damage model with Rankine′s failure initiation criterion, and (iv) random distribution of tensile strengths of individual finite elements.
The model was finally validated with experimental results on neutron-irradiated concrete. The simulation approach considers: (i) coupled hygro-thermal model to predict the temperature and humidity profile inside the specimen (ii) radiation-induced volumetric expansion of aggregates (RIVE) (iii) thermal, shrinkage and creep effects based on the temperature and humidity profile and (iv) isotropic damage model with Rankine’s criterion to determine failure initiation.
A mesoscale micro-structural framework is proposed in Multiphysics Object-Oriented Simulation Environment (MOOSE) finite element framework which represents the first step in this direction. As part of the framework, a coupled creep damage algorithm was developed and implemented in MOOSE. The algorithm considers creep through rheological models, while damage evolves exponentially as a function of elastic strain and creep strain. A characteristic length is introduced in the formulation such that the energy release rate associated with each element remains the same to avoid vanishing energy dissipation with mesh refinement. A creep damage parameter quantifies the effect of creep strain on the damage that was calibrated using three-point bending experiments with varying rates of loading.
The creep damage model was also validated with restrained ring shrinkage tests on cementitious materials containing compliant/stiff inclusions subjected to variable drying conditions. The simulation approach explicitly considers: (i) moisture diffusion driven differential shrinkage along the depth of the specimen (ii) viscoelastic response of aging cementitious materials (iii) isotropic damage model with Rankine′s failure initiation criterion, and (iv) random distribution of tensile strengths of individual finite elements.
The model was finally validated with experimental results on neutron-irradiated concrete. The simulation approach considers: (i) coupled hygro-thermal model to predict the temperature and humidity profile inside the specimen (ii) radiation-induced volumetric expansion of aggregates (RIVE) (iii) thermal, shrinkage and creep effects based on the temperature and humidity profile and (iv) isotropic damage model with Rankine’s criterion to determine failure initiation.
ContributorsSaklani, Naman (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramanian (Committee member) / Mobasher, Barzin (Committee member) / Hoover, Christian (Committee member) / Chawla, Nikhilesh (Committee member) / Arizona State University (Publisher)
Created2020
Description
The National Oceanic and Atmospheric Administration (NOAA)’s National Water Model (NWM) will provide the next generation of operational streamflow forecasts at different lead times across United States using the Weather Research and Forecasting (WRF)-Hydro hydrologic system. These forecasts are crucial for flood protection agencies and water utilities, including the Salt River Project (SRP). The main goal of this study is to calibrate WRF-Hydro in the Oak Creek Basin (OCB; ~820 km2), an unregulated mountain sub-watershed of the Salt and Verde River basins in Central Arizona, whose water resources are managed by SRP and crucial for the Phoenix Metropolitan area. As in the NWM, WRF-Hydro was set up at 1-km (250-m) resolution for the computation of the rainfall-runoff (routing) processes. Model forcings were obtained by bias correcting meteorological data from the North American Land Data Assimilation System-2 (NLDAS-2). A manual calibration approach was designed that targets, in sequence, the sets of model parameters controlling four main processes responsible for streamflow and flood generation in the OCB. After a first calibration effort, it was found that WRF-Hydro is able to simulate runoff generated after snowmelt and baseflow, as well as magnitude and timing of flood peaks due to winter storms. However, the model underestimates the magnitude of flood peaks caused by summer thunderstorms, likely because these storms are not captured by NLDAS-2. To circumvent this, a seasonal modification of soil parameters was adopted. When doing so, acceptable model performances were obtained during calibration (2008-2011) and validation (2012-2017) periods (NSE > 0.62 and RMSE = ~2.5 m3/s at the daily time scale).
The process-based calibration strategy utilized in this work provides a new approach to identify areas of structural improvement for WRF-Hydro and the NWM.
The process-based calibration strategy utilized in this work provides a new approach to identify areas of structural improvement for WRF-Hydro and the NWM.
ContributorsHussein, Abdinur Jirow (Author) / Mascaro, Giuseppe (Thesis advisor) / Vivoni, Enrique (Thesis advisor) / Xu, Tianfang (Committee member) / Arizona State University (Publisher)
Created2020
Description
This report analyzed the dynamic response of a long, linear elastic concrete bridge subject to spatially varying ground displacements as well as consistent ground displacements. Specifically, the study investigated the bridge’s response to consistent ground displacements at all supports (U-NW), ground displacements with wave passage effects and no soil profile variability (U-WP), and ground displacements with both wave passage effects and soil profile variability (V-WP). Time-history ground displacements were taken from recordings of the Loma Prieta, Duzce, and Chuetsu earthquakes. The two horizontal components of each earthquake time-history displacement record were applied to the bridge supports in the transverse and longitudinal directions. It was found that considering wave passage effects without soil profile variability, as compared with consistent ground displacements, significantly reduced the peak total energy of the system, as well as decreasing the maximum relative longitudinal displacements. The maximum relative transverse displacements were not significantly changed in the same case. It was also found that including both wave passage effects and soil profile variability (V-WP) generally resulted in larger maximum transverse relative displacements, across all earthquake time-histories tested. Similarly, it was found that using consistent ground displacements (U-NW) generally resulted in larger maximum longitudinal relative displacements, as well as larger peak total energy values.
ContributorsSeawright, Jordan Michael (Author) / Hjelmstad, Keith (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Kavazanjian, Edward (Committee member) / Arizona State University (Publisher)
Created2019
Description
Expansive soils pose considerable geotechnical and structural challenges all over the world. Many cities, towns, transport systems, and structures are built on expansive soils. This study evaluates stabilization of expansive soils using silicate solution extracted from rice husk taking advantage of an agricultural material waste. Rice husk ash production was optimized considering several factors including rinsing solution, rinsing temperature, burning time, and burning temperature. Results indicated that washing the rice husk with HCl (1M) produced an ash with surface area of 320 m2/g and 97% of silicon oxide. Two local soils were treated with sodium silicate solution, silica gel at pH 1.5, and silica gel at pH 4 to evaluate its mechanical properties at curing times of 1 day, 7 days, and 14 days. Results indicated that sodium silicate solution reduced the one-dimensional swell by 48% for Soil A, however, swell for soil B remained about the same. Silica gel at pH 1.5 reduced the one-dimensional swell by 67% for soil A and by 35% for soil B. Silica gel at pH 4 did also reduce the free swell by 40% for soil A and by 35% for soil B. Results also indicated that the swell pressures for all treated soils increased significantly compared to untreated soils. Soils treated with sodium silicate solution showed irregular compaction curves. Silica gel-treated soils showed a reduction in the maximum dry unit weight for both soils but optimum water content decreased for soil A and increased for soil B. Atterberg limits were also reduced for sodium silicate and silica gels-treated soils. Swelling index for bentonite showed a reduction by 53% for all treated bentonites. Soil-water characteristics curves (SWCC) for sodium silicate-treated soils remined almost the same as untreated soils. However, silica gels-treated soils retain more water. Surface area (SSA) decreased for sodium silicate-treated soil but increased for all silica gels-treated soils. It was concluded that curing times did not show additional improvement in most of the experiments, but the results remained about the same as 1-day treatment. The study demonstrated that silicate solution is promising and sustainable technique for stabilization of expansive soils.
Contributorsalharbi, hani (Author) / Zapata, Claudia (Thesis advisor) / Kavazanjian, Edward (Committee member) / van Paassen, Leon (Committee member) / Khodadaditirkolaei, Hamed (Committee member) / Arizona State University (Publisher)
Created2020
Description
Enzyme-induced carbonate precipitation (EICP) is an emerging technology for ground improvement that cements soil with calcium carbonate to increase strength and stiffness. EICP-improved soil can be used to support new facilities or it can be injected under existing facilities to prevent excessive deformation. The limitations for commercial adoption of EICP are the cost and the lack of implementation at field-scale. This research demonstrated two ways to reduce the cost of EICP treatment at field-scale. The first was a modification to the EICP solution such that lower amounts of chemicals are needed to achieve target strengths. The second was to use a simple and inexpensive enzyme extraction method to produce the enzyme at a large-scale. This research also involved a two-stage scale-up process to create EICP biocemented soil columns using a permeation grouting technique. The first stage was at mid-scale where 0.6 m x 0.3 m-diameter EICP biocemented soil columns were created in boxes. This work confirmed that conventional permeation grouting equipment and methods are feasible for EICP soil treatment because the columns were found to have a uniform shape, the injection method was able to deliver the EICP solution to the edges of the treatment zone, and downhole geophysics was effectively used to measure the shear wave velocity of the biocemented soil mass. The field-scale stage was performed in the Test Pit facility at the Center for Bio-mediated and Bio-inspired Geotechnics' Soils Field Laboratory. Seven biocemented soil columns were created with diameters ranging from 0.3-1 m and heights ranging from 1-2.4 m. Effective implementation at this scale was confirmed through monitoring the injection process with embedded moisture sensors, evaluating the in situ strength improvement with downhole geophysics and load testing, and testing of the excavated columns to measure shear wave velocity, dimensions, carbonate content, and strength. Lastly, a hotspot life cycle assessment was performed which identified ways to reduce the environmental impacts of EICP by using alternative sourcing of inputs and extraction of byproducts. Overall, this research project demonstrates that EICP is a viable ground improvement technique by way of successfully producing field-scale biocemented soil columns.
ContributorsMartin, Kimberly Kathryn (Author) / Kavazanjian, Jr., Edward (Thesis advisor) / Zapata, Claudia E. (Committee member) / van Paassen, Leon (Committee member) / Arizona State University (Publisher)
Created2021
Description
There is a high demand for customized designs of various types of cement-based materials in order to address specific purposes in the construction field. These demands stem from the need to optimize the cementitious matrix properties and reinforcement choices, especially in high reliability, durability, and performance applications that include infrastructure, energy production, commercial buildings, and may ultimately be extended to low risk/high volume applications such as residential applications. The typical tools required to guide practicing engineers should be based on optimization algorithms that require highly efficient capacity and design alternatives and optimal computational tools. The general case of flexural design of members is an important aspect of design of structural members which can be extended to a variety of applications that include various cross-sections such as rectangular, W-sections, channels, angles, and T sections. The model utilized the simplified linear constitutive response of cement-based composite in compression and tension and extends into a two-segment elastic-plastic, strain softening, hardening, tension-stiffening, and a multi-segment system. The generalized parametric model proposed uses a dimensionless system in the stress-strain materials diagram to formulate piecewise equations for an equilibrium of internal stresses and obtains strain distributions for the closed-form solution of neutral axis location. This would allow for the computation of piecewise moment-curvature response. The number of linear residual stress implemented is flexible to a user to maintain a robust response. In the present approach bilinear, trilinear, and quad-linear models are addressed and a procedure for incorporating additional segments is presented. Moreover, a closed-form solution of moment-curvature can be solved and employed in calculating load-deflection response. The model is adaptable for various types of fiber-reinforced and textile reinforced concrete (FRC, TRC, UHPC, AAC, and Reinforced Concrete). The extensions to cover continuous fiber reinforcement such as textile reinforced concrete (TRC, FRCM) strengthening and repair are addressed. The theoretical model is extended to incorporate the hybrid design (HRC) with continuous rebar with FRC to increase the ductility and ultimate moment capacity. HRC extends the performance of the fiber system to incorporate residual capacity into a serviceability-based design that reduced the reliance on the design based on the limit state. The design chart for HRC and as well as conventional RC has been generated for practicing engineering applications. Results are compared to a large array of data from experimental results conducted at the ASU structural lab facilities and other published literature.
Contributorspleesudjai, chidchanok (Author) / Mobasher, Barzin (Thesis advisor) / Neithalath, Narayanan (Committee member) / Rajan, Subramaniam (Committee member) / Arizona State University (Publisher)
Created2021
Description
In the structural engineering industry, the design of structures typically follows a prescriptive approach in which engineers conform to a series of code requirements that stipulate the design process. Prescriptive design is tested, reliable, and understood by practically every structural engineer in the industry; however, in recent history a new method of design has started to gain traction among certain groups of engineers. Performance-based design is a reversal of the prescriptive approach in that it allows engineers to set performance goals and work to prove that their proposed designs meet the criteria they have established. To many, it is an opportunity for growth in the structural design industry. Currently, performance-based design is most commonly utilized in regions where seismic activity plays an important role in the design process. Due to its flexible nature, performance-based design has proven extremely useful when applied to unique structures such as high-rises, stadiums, and other community-centric designs. With a focus placed on performance objectives and not on current code prescriptions, engineers utilizing performance-based design are more adept to implement new materials, design processes, and construction methods, and can more efficiently design their structures to exist on a specific area of land. Despite these many cited benefits, performance-based design is still considered an uncommon practice in the broad view of structural design. In order to ensure that structural engineers have the proper tools to practice performance-based design in instances where they see fit, a coordinated effort will be required of the engineers themselves, the firms of which they are employed, the professional societies to which they belong, and the educators who are preparing their next generation. Performance-based design holds with it the opportunity to elevate the role of the structural engineer to which they are informed members of the community, where the structures they create not only perform according to design prescriptions, but also perform according to the needs of the owners, engineers, and society.
ContributorsMaurer, Cole (Author) / Hjelmstad, Keith (Thesis advisor) / Chatziefstratiou, Efthalia (Committee member) / Dusenberry, Donald (Committee member) / Arizona State University (Publisher)
Created2021
Description
The construction industry requires effective communication between project stakeholders in various locations. This communication can be facilitated through in person site visits or phone calls, but these methods can also lead to wasted travel time and misunderstandings from omitting critical site details, respectively. Theoretically, Augmented Reality (AR) can be as effective as in person site meetings. The vast majority of studies that have explored AR, for communication, have done so in controlled environments. This work investigates the efficacy of AR calls in uncontrolled settings (i.e., construction sites), by interviewing practitioner participants to identify common beneficial and detrimental behaviors and perceptions. Furthermore, the author examines the factors that might impact exchanges between people using AR as a tool of communication. The combination of these findings concludes that AR is effective in supporting remote communication between multiple locations. The contribution of this work is in documenting the challenges and opportunities of using AR in a live construction environment, where factors may be present that have not yet been studied by researchers exploring AR in a controlled setting. This contribution will guide subsequent academic research, as well as practical adoption of emerging AR tools in the industry.
ContributorsKassis, Rita (Author) / El Asmar, Mounir ME (Thesis advisor) / Ayer, Steven SA (Thesis advisor) / Parrish, kristen KP (Committee member) / Arizona State University (Publisher)
Created2021