Civil & Environmental Engineering Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2753
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Item PERFORMANCE OF REPAIRED CONCRETE COLUMNS UNDER AXIAL LOADING(2019) Seyidoglu, Murat; Zhang, Yunfeng; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The purpose of this research was to determine the performance and axial load capacity of repaired reinforced concrete columns under compressive loading. While various concrete column strengthening methods, using concrete or carbon fiber reinforcing polymer (CFRP) jacketing, have been exhaustively researched, there is an insufficient amount of research regarding the performance of column repairs utilizing concrete removal and replacement. To research this topic, nine reinforced, one-third scale concrete columns were cast; and, six of these columns were repaired with conventional concrete repair methods recommended by the American Concrete Institute’s Guide to Concrete Repair (546-14). Shallow (extending up to the exterior faces of column ties) and deep repairs (extending behind the vertical bars) were performed at the bases of the columns by chipping the concrete with a handheld chipping hammer and patching with a shrinkage compensated repair mortar as it is commonly done for repairing corrosion related spalls. Results of the axial compression loading tests and failure patterns of the repaired columns were compared to that of the control samples. It was found that all repaired concrete columns achieved comparable load capacity values and exhibited the same failure mode as the intact columns.Item Seismic Resilience Study of Steel Concentrically Braced Frame Structure with Dual Viscous and Metallic Hysteretic Damper(2019) Xu, Jianshu; Zhang, Yunfeng; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Steel concentrically braced frames（CBF）are popular seismic resistant structural systems widely used all over the world due to their high elastic stiffness and moderate ductility for many decades. However, conventional CBFs are subject to soft-story damage pattern which may lead to collapse caused by overly large drift concentrated in one story in strong earthquakes; measures to enhance the seismic resilience of CBFs is thus desirable. This study looks into quantifying the seismic resilience of CBFs with and without dual-action damping devices by following the newly released 2018 ed. FEMA P58 procedure. The dual-action damping device includes a viscous damper and metallic hysteretic dampers which are activated at different timing: viscous damper always active and effective in controlling story drift during small and moderate earthquakes, while metallic hysteretic dampers are activated only when the story drift exceeds a pre-specified value during strong earthquakes. A six-story steel CBF and a three-story steel CBF buildings designed by SAC Steel Project research (1999) are adopted as prototype building to demonstrate the effectiveness of dual-action damping device in enhancing the seismic resilience of CBFs. Nonlinear static analyses as well as nonlinear time-history analysis are performed to obtain the Engineering Demand Perimeters (EDP) required for seismic resilience evaluation. Collapse Fragility is developed based on incremental dynamic analysis (IDA) by SPO2IDA Tool. The distribution function of Decision Variables (DV), including Repair cost, Repair time, Casualties etc., is obtained through Monte-Carlo simulation of prior nonlinear time-history analysis EDP by Performance Assessment Calculation Tool (PACT). It is found from this study that the Collapse Risk and the Potential Loss of the prototype structure with dampers have been significantly reduced, suggesting the dual-action damping device provides a beneficial alternative for enhancing the seismic resilience of CBFs.Item Urban Heat Projections and Adaptations in a Changing Climate, Washington D.C. as a Case Study(2019) Zhang, Yating; Ayyub, Bilal M; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Carbon emission from human activities has changed the Earth’s overall climate and intensified extreme weather and climate events. Climate risks are regionally uneven due to different vulnerability levels of populations, infrastructures, and natural resources. Assessing local-scale risk is important in supporting climate preparation, adaptation planning, and policy development for cities to overcome climate change. This dissertation developed the Asynchronous Regional Regression Model (ARRM) that statistically downscales data of Coupled Model Intercomparison Project Phase Five (CIMP5) into locations of observing stations, employed the Weather Research and Forecasting (WRF) model that dynamically downscales data of Community Earth System Model version one (CESM1) into fine-grid results, and proposed a framework to assess adaptation strategies for vulnerable infrastructure systems incorporating the probabilistic risk approach. Based on those models and methods, this dissertation projected the trend and level of the urban heat island (UHI) effect and heat waves in the rest of the 21st century for Washington D.C. and its surrounding areas, evaluated mitigation options for heat waves, and assessed adaptation strategies for electrical power systems in such area. Projections based on the higher greenhouse gas (GHG) concentration scenario, Representative Concentration Pathway (RCP) 8.5, indicate a growing trend of heat waves at Washington D.C. in the rest of the century. The amplitude of heat waves may grow by 5.7°C, and frequency and duration may increase by more than twofold by the end of the century. The UHI effect may increase in summer and decrease in winter. The lower scenario, RCP 2.6, leads to slight decay of heat waves after a half-century of increase, and a minor change in the UHI effect. Five heat wave mitigation strategies based on cool roofs, green roofs, and reflective pavements were evaluated in three future time periods. Results indicated that applying cool roofs and green roofs in the city scale can effectively reduce heat wave amplitude and duration, whereas the effectiveness of reflective pavements is negligible. However, reflective pavements can be more cost-effective than green roofs because of their low initial and maintenance costs. Electrical power systems are particularly vulnerable to extreme heat. Results indicated that power outage risk caused by temperature rise may increase seventyfold in the Washington metro area by the end of the century. If summer peak load on the electrical grid is cut by three quarters, there would be a twentyfold increase instead. This reduction is achievable by installing solar panels on building roofs, which can add an average generation capacity of 13.02 GW to the existing power system. Increasing the use of rooftop photovoltaics (PV) can increase the level of benefits.Item THE IMPACT OF MULTIPLE SPATIAL LEVELS OF THE BUILT ENVIRONMENT ON NONMOTORIZED TRAVEL BEHAVIOR AND HEALTH(2019) Mahmoudi, Jina; Zhang, Lei; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Over the past several decades, the primacy of the automobile in American travel culture has led to rising congestion and energy consumption levels, rampant air pollution, sprawled urban designs, pervasiveness of sedentary behaviors and lifestyles, and prevalence of many health problems. Nonmotorized modes of travel such as walking and bicycling are sustainable alternatives to the automobile and suitable remedies to the adverse environmental, economic, and health effects of automobile dependency. As research continues to reveal the many benefits of nonmotorized travel modes, identification of the factors that influence people’s levels of walking and bicycling has become essential in developing transportation planning policies and urban designs that nurture these activities, and thereby promote public health. Among such factors are the built environment characteristics of the place of residence. To date, research on the impact of the built environment on nonmotorized travel behavior has been focused on neighborhood-level factors. Nonetheless, people do not stay within their neighborhoods; they live and work at a regional scale and travel to different places and distances each day to access various destinations. Little is known, however, about the impact of built environment factors at larger scales including those representing the overall built environment of metropolitan areas on nonmotorized travel behavior and health status of residents. Guided by the principles of the ecological model of behavior, this dissertation systematically tests the impact of the built environment at hierarchical spatial scales on nonmotorized travel behavior and health outcomes. Advanced statistical techniques have been employed to develop integrated models allowing comprehensive examination of the complex interrelationships between the built environment, nonmotorized travel, and health. Through inclusion of built environment factors from larger spatial scales, this research sheds light on the overlooked impact of the macro-level built environment on nonmotorized travel and health. The findings indicate that built environment factors at various spatial scales—including the metropolitan area—can influence nonmotorized travel behavior and health outcomes of residents. Thus, to promote walking and bicycling and public health, more effective policies are those that include multilevel built environment and land use interventions and consider the overall physical form of urban areas.Item 3D IMAGE ANALYSIS OF CT DATA OF CONCRETE CYLINDER SUNDERGOING DELAYED ETTRINGTIE FORMATION(2019) Shi, Kuo; Amde, Amde M; Livingston, Richard A; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The strains in a concrete caused by delayed ettringite formation (DEF) are conventionally expressed in terms of the one-dimensional linear expansion. However, concrete is not a homogeneous material, and differences in the volume change between the inert aggregates and the reactive cement paste will produce variations in local displacements that cannot be detected by the linear expansion variable. With CT slices offered by Simultaneous neutron and X-ray computed tomography (SNXCT), this thesis applies image analysis algorithms to quantify the distortion of cylinder over time due to delayed ettringite formation. The research reported in this thesis concerned the development of several MATLAB programs to apply image analysis algorithms to quantify the distortion of cylinder over time in terms of summary variables. These included mean radial expansion, deviation from circularity, vertical tilt angle and rotation, void area fraction and the displacement of microbead internal reference points.Item ADVANCED DATA ANALYTICS AND MESOSCOPIC DYNAMIC TRAFFIC ASSIGNMENT SIMULATION FOR TRAFFIC IMPACT ANALYSIS OF MARYLAND CASINOS(2019) Donaldson, David; Zhang, Lei; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Three full-service casinos recently opened in Maryland: Live! Casino at the Arundel Mills Mall (June 2012), Horseshoe in Downtown Baltimore (August 2014), and MGM at the National Harbor (December 2016). The increased travel demand associated with such large entertainment complexes prompted an effort to quantify each facility’s impact on regional and local traffic patterns; therefore, a three-pronged analysis was conducted. First, historic vehicle probe data were analyzed to quantify and visualize the observed, local traffic impact for selected months before and after each casino became operational. Subsequently, an open-source mesoscopic DTA simulator named DTALite modeled the regional impact of the before/after scenarios as well as a special event scenario (e.g. Baltimore Ravens’ football game). The paper’s final component explored two innovative trip generation estimation methods to supplement the ITE Manual’s data limitation for casinos by utilizing aggregated mobile device trip data and an origin-demand adjustment system imbedded within DTALite. Ultimately, the data analytics and simulation-based modeling revealed no major traffic impact was generated by any casino. Moreover, upon comparison with ground truth count data, the origin-demand estimation technique out-performed both the ITE-based and location-based trip estimation methods.Item DEVELOPMENT NEEDS AND CRITICAL CHALLENGES IN THE APPLICATION OF CONSTRUCTION AUTOMATION AND ROBOTICS(2019) WANG, HEQIN; Skibniewski, Miroslaw; Cui, Qingbin; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Construction automation and robotics is a construction technology by which the process is conducted without or with limited human assistance, with the goal of advancing construction. With many procedures in the construction life cycle, there are plentiful applications construction automation and robotics can be applied in those steps, including excavation, framing, surveying, painting, pre-fabrication, tunneling, inspection and maintenance, etc. This study compared automation and robotics entities between 2010s and 1980s-1990s, distributed a questionnaire survey in the construction industry after which critical needs for applying the technology and influential factors in applying the technology are studied, and conducted case studies of typical companies that embraced construction automation. An international conference on this topic was held to provide professional opinions on future automation application. The results reveal development needs and critical challenges in the application of automation and robotics and provide guidance in future studies.Item Success Factors for 3D Printing Technology Adoption in Construction(2019) Pimpley, Pankhuri; Skibniewski, Miroslaw J; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)3D printing or Additive Manufacturing (AM) technology is taking small, slow steps in the construction industry. It is dominantly used for prototyping purposes, and even with the several benefits it can bring to building technology, it is not being adopted on the desired scale. Several inter-organizational and intra-organizational factors play a critical role in determining the extent of 3D printing technology adoption in construction. This dissertation uses various technology innovation theories and studies to identify factors which might affect the 3D printing technology adoption in construction. The research investigates these elements from different stakeholder’s perspective and categorizes and analyzes them. The approach includes elaborate literature review, correspondence with professionals, and case studies. The success factors are assessed based on questionnaire responses from organizations and personnel who are interested in or are working with construction 3D printing. This research will help in understanding the implementation of the 3D printing technology in construction and provide a framework to guide efforts in the direction of technology adoption into the construction practice.Item Development of a Traffic Incident Management Support System(2019) Won, Minsu; Chang, Gang-Len; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Highway incidents, primary contributors to traffic congestion, often cause not only significant delays to the daily roadway users, but also the reliability of transportation systems and even the productivity of the supply-chains of some vital industry sectors. To mitigate the impacts of such incidents and to recover the performance of highway systems as safely and quickly as possible, it is essential that the responsible highway agencies shall operate an efficient system to detect an incident, estimate the required clearance duration, assess the resulting traffic impacts, and then take necessary control actions. To do so, the most critical task is to have a reliable estimate of a detected incident’s impacts. However, providing the information of time-varying incident impacts to the general public at the desirable level of accuracy is a challenging task due to difficulties in having sufficient data and the complex relations between key factors contributing to the incident impacts. The purpose of this study is to develop a traffic incident management (TIM) support system which is capable of providing robust and reliable information with respect to the estimated clearance duration and capacity drop of a detected incident and its temporal as well as spatial evolution of traffic impact patterns. The proposed incident management support system consists of two main components, one for estimating the incident duration and the other for computing the resulting capacity drop of the roadway segment plagued by the incident. The first component servers to provide a robust incident duration estimate, using several specially-designed methods to effectively tackle the unique distribution patterns of the incident duration data and their complex correlations among contributing factors, which includes classification model, continuous model, and supplemental rules to first produce an initial interval estimate, and then a point estimate along with the outlier information. The second component is designed to estimate the additional roadway capacity reduction (i.e., capacity drop) due to the lane blockages by incidents and the response operations, allowing the control center operators to assess the spatial and temporal incident impacts on the highway network, and take necessary control actions in a timely manner. The proposed TIM support system has the following key features: 1) providing the initial estimate of incident duration, based on limited data available at the early stage of incident responses and operations; 2) updating the estimated incident duration with a specially-design process and models when more data become available; 3) implementing an integrated estimation methodology to circumvent the variances due to the unique characteristics associated with recorded incident data (e.g., highly skewed distribution, complex correlations among the explanatory variables, mixed qualitative and quantitative variables, and heteroscedasticity); 4) generating the estimated additional capacity reduction for the highway segment plagued by the lane-closure and lane-changing activities during the incident clearance operations using a reliable and trackable analytical model; and 5) providing a convenient and effective computation process to estimate time-varying incident impacts, such as queues and delays, in the highway network for real-time applications.Item SOLUBLE SALTS REDUCTION AND METALS BEHAVIOR OF DREDGED SEDIMENT FOR REUSE IN HIGHWAY SLOPE APPLICATIONS(2019) Huffert, Michelle B; Davis, Allen P.; Aydilek, Ahmet H.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Waterways are dredged routinely to maintain navigation channels, resulting in large quantities of dredged materials (DM) that require disposal. This study examines the innovative reuse of DM as a topsoil alternative in highway slopes. The dredged material met Maryland Department of Transportation, State Highway Administration (MDOT SHA) topsoil requirements for pH, organic matter, and particle size distribution, and required 122 cm (48 inches) of rainwater to leach soluble salts to below limits. Column leach tests were performed on DM and topsoil to evaluate metal leaching behavior; extractions were performed to determine total and potentially mobile metals content. DM leached metals concentrations below drinking water maximum contaminant levels (MCLs) for >95% of the samples tested, and passed a toxicity characteristic leaching procedure (TCLP). Extraction data showed higher total concentrations of arsenic, chromium, and lead as compared to topsoil, but similar concentrations in the EDTA-extracted fractions indicating that metals are strongly bound.