2021

Permanent URI for this collectionhttps://hdl.handle.net/1807/104121

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Now showing 1 - 20 of 91
  • ItemOpen Access
    Effects of Microbially Induced Carbonate Precipitation on Diffuse Double Layer and Particle Fabric of Oil Sands Fine Tailings
    (Canadian Science Publishing, 2021-12-20) Liu, Qianwen; Montoya, Brina
    Microbially induced carbonate precipitation (MICP) is a sustainable biological process that catalyzes carbonate mineral precipitation within geomaterials. This study evaluates the performance and mechanisms of the MICP treatment for flocculating the oil sands fine tailings (FT). Column tests showed that the untreated FT did not decant during the 31 days. However, the MICP technique shortened the dewatering process. To elucidate the mechanisms of the MICP-induced flocculation of the FT, the diffuse double layer (DDL) thickness and microstructure of the specimens were evaluated. Three chemical equilibrium scenarios that gradually considered the MICP-biochemical reactions were explored to analyze the change of the DDL thickness. The results showed that increasing of ionic strength by urea hydrolysis decreased the DDL thickness. The fabric observation indicated that the specimens with the most calcium carbonate precipitation had the densest fabric. In summary, the MICP technique densified the fabric of FT via ureolysis process and precipitating minerals.
  • ItemOpen Access
    Influence of Headwater Reservoirs on Climate Change Impacts and Flood Frequency in the Kabul River Basin
    (Canadian Science Publishing, 2021-11-08) Taraky, Yar M.; Liu, Yongbo; Gharabaghi, Bahram; McBean, Edward; Daggupati, Prasad; Shrestha, Narayan
    While climate change impacts vary globally, for the Kabul River Basin (KRB), concerns are primarily associated with frequent flooding. This research describes the influence of headwater reservoirs on projections of climate change impacts and flood frequency, and how the riparian countries can benefit from storing of floodwaters for use during dry seasons. Six climate change scenarios and two Representative Concentration Pathways (RCPs) are used in three periods of a quarter-century each. The Soil and Water Assessment Tool (SWAT) is used to assess how the proposed reservoirs will reduce flooding by ~38% during the wet season, reduce the flood frequency from five to 25 years return period, and increase low flows by ~110% during the dry season, which reflect an ~17.5% reduction in the glacier-covered area by the end of the century. The risks and benefits of reservoirs are highlighted in light of the developmental goals of Afghanistan and Pakistan.
  • ItemOpen Access
    Semi-quantitative seismic risk screening tool for existing buildings in Canada
    (Canadian Science Publishing, 2021-12-13) Fathi-Fazl, Reza; CAI, ZHEN; Corts-Puentes, W. Leonardo; Fazileh, Farrokh
    The National Research Council Canada (NRC) recently developed a semi-quantitative seismic risk screening tool (SQST) for existing buildings in Canada. The SQST aims to supersede the Manual for Screening of Buildings for Seismic Investigation developed by NRC in the early 1990s. The SQST consists of three key components: (1) a structural scoring system that quantitatively assesses the structural seismic risk based on probability of collapse; (2) a non-structural component scoring system that qualitatively assesses the seismic risk of non-structural components based on seismic demand; and (3) a ranking procedure that prioritizes potentially hazardous buildings for seismic evaluations and possible upgrading. The SQST intends to inexpensively identify and exempt buildings with acceptable life safety risk and optimize the allocation of resources to assess the seismic risk of portfolios of buildings. Seismic screening with the SQST can be completed with either paper-based screening forms or a web-based application. The applicability of the SQST is demonstrated by conducting a pilot study for 33 existing buildings across Canada.
  • ItemOpen Access
    Evaluation of electrical resistivity and maturity for estimating the early-age properties of pre-packaged concrete
    (Canadian Science Publishing, 2021-11-16) Tagliaferri De Grazia, Mayra; F. M. Sanchez, Leandro; De Souza, Diego J.; Ismail, Lamiaa; Noël, Martin; Decarufel, Sarah
    Although 28-day concrete compressive strength is often used as a quality control indicator, early-age mechanical properties are becoming more critical to optimize construction scheduling. Electrical resistivity (ER) and maturity can be used to appraise mechanical properties’ gain over time. Although these methods are well-defined for conventional concrete, there is a lack of studies using these techniques to predict strength of pre-packaged concrete mixes containing distinct materials. This paper aims to explore the feasibility of estimating early-strength gain of pre-packaged repair materials through ER and maturity. Calibration curves were developed using cylinders cured at room temperature and compared to samples cured under low/fluctuating temperature conditions. The average predicted-to-experimental strength ratios using ER and maturity method ranged from 1.07-1.17 and 0.86-1.16, respectively. Moreover, a statistical analysis of variance confirmed that there is no significant scatter within the results obtained from the same mixture.
  • ItemOpen Access
    Assessment of Sediment Arsenic and Iron Occurrence and Leaching Potential in a Potable Water Treatment Wastewater Stabilization Pond System
    (Canadian Science Publishing, 2021-11-26) Ekhlasi Nia, Ali; Bull, Harrison; Asadi, Mohsen; McPhedran, Kerry
    Wastewater stabilization ponds (WSPs) are commonly used to reduce wastewater metal(loid) concentrations from drinking water treatment plants (DWTPs) through sedimentation. However, this results in increased sediment concentrations that can be released back into the overlying water. Thus, our goal was to evaluate the WSP metal(loid)s occurrence and leaching potential. Currently, a Saskatchewan based DWTP’s WSP system was investigated given historically elevated effluent As and Fe concentrations. The WSP consists of five ponds that were sampled on six occasions in 2019 and 2020. In addition, sediments were used in laboratory-based experiments to determine their leaching potential. Overall, the sediments were found to contain elevated concentrations of As and Fe with 25 to 400 and 10,000 to 45,000 mg/kg, respectively. Leaching experiments indicated that the pond sediments could potentially release As and Fe with log Kd values ranging from 2.21 to 4.31 L/kg, while Fe ranged from 3.32 to 5.53 L/kg.
  • ItemOpen Access
    Exploring Implicit Relationships between Pavement Surface Friction and Vehicle Crash Severity Using Interpretable Extreme Gradient Boosting Method
    (Canadian Science Publishing, 2021-12-04) Zhao, Guangyuan; Jiang, Yi; Li, Shuo; Tighe, Susan
    Pavement friction has been identified as crucial in traffic safety. Since the Highway Safety Manual prediction algorithm is often based on crash frequency, the crash severity distribution might be assumed unchanged before and after the countermeasure. However, pavement surface treatments can improve the friction to different levels, by which crash severity outcomes may vary greatly. To explore the implicit effects of pavement friction on vehicle crash severity, this paper first validates the extreme gradient boosting model performance and then the Shapley additive explanations interaction values are employed to interpret individual features and the nonlinear interactions among predictors. Under various scenarios, the XGBoost output probability is utilized to convert into dynamic crash severity distributions. Results also indicate that friction becomes more significant when the friction number is less than 38, and immediate corrective actions are needed when the friction number is below 20.
  • ItemOpen Access
    A life cycle thinking centred methodology for energy retrofit evaluation
    (Canadian Science Publishing, 2021-12-13) Toufeili, Rania; Ruparathna, Rajeev; Tam, Edwin
    Energy retrofits can improve the sustainability of a building by decreasing the energy consumption and resulting GHG emissions throughout its life. Adopting critical life cycle thinking is crucial when deciding on how to implement building retrofits. This article first evaluates innovative and proven building energy retrofits through a life cycle thinking lens. Next, it develops a methodological framework to assess building retrofits using four principal measures: environmental, economic, social, and technical criteria. The proposed method was demonstrated using an institutional building in Windsor, Ontario, as a case study. The case study revealed that the selected retrofit might result in the least energy savings, but it is still the preferred alternative because other factors can present valuable trade-offs that are desirable. The outcomes of this research, with the demonstrated tool, will assist building managers in determining the optimal energy retrofit for their buildings.
  • ItemOpen Access
    OPTIMIZED MAINTENANCE PLAN FOR OIL AND GAS PIPELINES
    (Canadian Science Publishing, 2021-01-31) El-Abbasy, Mohammed Saeed; Zayed, Tarek; Mirahadi, Farid; Parvizsedghy, Laya; Senouci, Ahmed
    Oil and gas pipelines transport millions of dollars of products every day making the optimization of their long-term maintenance strategies an essential target for practitioners. Thus, this paper aims to optimize the maintenance plan of such pipelines by maximizing their lifetime average condition with the minimum possible cost. This is achieved in three steps: (1) developing a life-cycle cost model for such pipelines to determine their net present value (NPV) based on the different rehabilitation actions applied throughout their lifetime; (2) establishing a strategy to determine the condition index of such pipelines before and after any rehabilitation action applied throughout their lifetime; and (3) formulating the optimization model and applying the elitist non-dominated sorting genetic algorithm (NSGA-II) to determine the optimum maintenance plans for such pipelines. The optimization model is applied on a real-life case study to demonstrate its applicability.
  • ItemOpen Access
    Monotonic Property of Steel-RC Composite Beams Strengthened with Externally Pre-stressed Tendons
    (Canadian Science Publishing, 2021-12-13) El-Zohairy, Ayman; Alsharari, Fahad; Salim, Hani H; Arafa, Ibrahim; Nawar, Mahmoud
    This study presents an experimental investigation on composite beams (CB) to explore the effectiveness of adding external post-tensioning (EPT) force, as a strengthening technique, on the monotonic flexural performance of composite samples. Two experiments on CB were conducted under three-point loading. High strength steel strands post-tensioned to 46% of the ultimate strength were used to apply the EPT. Moreover, a Finite Element (FE) model is developed to present numerical investigations on the monotonic and fatigue behaviors of the CB with and without EPT by considering the slip between the concrete slabs and steel beams as well as the fatigue deterioration in the concrete slabs. A FE parametric study is conducted using the proposed FE model to investigate the effect of steel beam grade, tendon eccentricity, span-to-depth ratio, and fatigue loading. The optimum span-to-depth ratio to obtain the maximum contribution of the EPT force in improving the CB capacities is 9.0.
  • ItemOpen Access
    Performance Comparison of Asphalt Emulsion Stabilized Granular Base Modified with Cement or Asphaltenes
    (Canadian Science Publishing, 2021-11-09) Uddin, Muhammad Misbah; Kamran, Farshad; Hashemian, Leila
    Asphalt emulsion is a common material used for pavement base course stabilization, and cement is usually added as an active filler to improve the stability of asphalt emulsion mixtures further. However, using cement in these mixes has several drawbacks, including high material costs and environmental issues. On the other hand, asphaltenes is a waste by product derived from the processing of Alberta oil-sands bitumen that could be used for the same purpose. This investigation compares the impact of cement and asphaltenes as additives to asphalt emulsion-stabilized layers. To compare the performance properties, cement- and asphaltenes-modified mixtures are prepared at different concentrations. The performance properties of the modified mixtures are investigated by conducting a series of tests including Marshall stability, indirect tensile strength, IDEAL-CT, and tensile strength ratio. In addition, to evaluate low-temperature cracking resistance of the mixtures, indirect tensile strength test is conducted at 0 C and −10 C.
  • ItemOpen Access
    Improvements in the Airtightness of Housing in Richmond, British Columbia
    (Canadian Science Publishing, 2021-11-20) Foroushani, Sepehr
    Controlling air leakage through the building envelope remains a challenge, especially in light of the imperative to transition to a net-zero energy building sector and the increasing importance of indoor air quality during extreme weather events such as wildfires. The British Columbia Energy Step Code is a performance-based compliance option in the British Columbia Building Code which is intended to provide a transition pathway to net-zero energy ready construction by 2032. For small residential buildings, performance targets entail thresholds for the measured air leakage rate through the building envelope. This paper reports on the airtightness of the first 145 single- and two-family dwellings built under the Energy Step Code in Richmond, BC. Although the first phase of the implementation of the Energy Step Code in Richmond entailed no airtightness targets (only testing), results indicate improvement compared to the historical levels of airtightness in the region.
  • ItemOpen Access
    Integrating acceleration signal processing and image segmentation for condition assessment of asphalt roads
    (Canadian Science Publishing, 2021-10-28) Sprague, William; Rezazadeh Azar, Ehsan
    A proactive road maintenance system enables agencies to better allocate resources to manage their road networks. An inventory of the roads’ conditions is an essential component of such maintenance program. This research project proposes a hybrid system to asses the condition of the asphalt roads, which uses a dashboard-mounted smartphone to simultaneously collect the acceleration response of a vehicle and the video footage of the road surface while driving. The system analyzes acceleration data for anomalous events that could indicate a defect. Then the computer vision module of the system applies semantic segmentation in the corresponding frame to the detected anomaly to identify defects. This system demonstrated 84% recall and 88% precision rates in detection of anomalies in two road segments. Despite these promising results, the system can only detect the defects that are passed over and it could miss some defects with small acceleration responses, such as traverse cracks.
  • ItemOpen Access
    Investigation of Climate Change Impacts on Early-Age Cracking of Jointed Plain Concrete Pavements in Canada
    (Canadian Science Publishing, 2021-10-31) Shafiee, Mohammad; Maadani, Omran
    Canada’s climate is warming at a rate about double the global average, leading to potential negative impacts on public infrastructures such as Jointed Plain Concrete Pavement (JPCP). In light of this reality of changing climate, the work contained in this paper is aimed at evaluating JPCP’s early-age behavior in response to environmental conditions. HIPERPAV software and the associated models developed by the U.S. Federal Highway Administration (FHWA) were used to identify cracking potential. A sensitivity analysis was performed to assess the effect of different levels of air temperature, mix temperature, base layer temperature, wind speed and relative humidity. Additionally, projected extreme temperatures predicted by Canadian Regional Climate Model (CanRCM) were used to determine the relative impact of climate change on cracking risk. The results demonstrated the increased cracking risk under changing climate in several Canadian cities by mid-century and highlighted the importance of developing a pathway forward for climate adaptation.
  • ItemOpen Access
    Nonlinear soil-structure behavior of a deployable and compliant anchor system
    (Canadian Science Publishing, 2021-10-31) Sychterz, Ann; Bernardi, Isabella; Tom, Joe G; Beemer, Ryan D.
    This paper presents a novel compliant geo-structural systems bio-inspired by awns on grass seeds for increasing anchor capacity while minimizing material usage. A compliant deployable structure is here defined as a system that reacts to global displacements by continued elastic shape change and awns are slender flexible structures rigidly connected to the exterior of an anchor. When the anchor is loaded in tension, the awns react off the soil mass and deploy outwards from the pile shaft, enabling space-saving measures for transportation. This paper creates a structural pushover model to establish awn deformations and stress values, a scale model of the compliant system fabricated using additive manufacturing, geo-plasticity numerical models of soil awn interaction, and a finite element model of an example application. This research elucidates the soil displacement mechanisms around the awns, the structural deformation of individual awns, and the enhancement of overall anchor capacity due to awn deployment.
  • ItemOpen Access
    Generating Labour Cost Budget for a Construction-Oriented Fabrication Facility: Simulation-based Resource Scheduling Approach
    (Canadian Science Publishing, 2021-10-31) Zahedi, Leila; Lu, Ming
    A novel labour-hour budgeting methodology is proposed by integrating productivity concepts in project scheduling and budgeting to enhance the accuracy of labour cost budgeting for planning labour-intensive projects. The proposed methodology applies discrete event simulation approach to represent crew formation, labour resource utilization and labour resource flowing between consecutive activities, which allows for quantitatively characterizing the impact of labour semi-productive time on labour cost budgeting as a time-dependent variable. Simulation-based assessment of variations in crew sizes and labour allocations is conducive to reducing semi-productive time and thus enhancing the cost performance of the whole project. The proposed methodology is then applied in a real-world case study for planning steel girder fabrication projects in construction of highway bridges. Not limited to budgeting for labour resources in construction-oriented fabrication facility, the research contributions are also significant to other construction planning settings where limited resources are shared and utilized among different activities.
  • ItemOpen Access
    Automated Framework for Extracting Sidewalk Dimensions from Images Using Deep Learning
    (Canadian Science Publishing, 2021-10-14) Halabya, Ayman; El-Rayes, Khaled
    State and local governments are required by federal and state laws to provide and maintain accessibility on their sidewalks and pedestrian facilities. They need to conduct and frequently update self-evaluation to assess the compliance of their sidewalks and pedestrian facilities with accessibility requirements and identify any barriers that limit or deny access for people with disabilities to public programs, services, or activities. This paper presents the development of an automated framework that is capable of (1) providing a cost-effective and practical methodology for conducting self-evaluations using sidewalk images, (2) creating 3D models of existing sidewalks that can be used in analyzing their conditions, and (3) automatically extracting sidewalk dimensions and geometry from sidewalk input images. A case study of a small pedestrian network that includes 830 meters of sidewalks was analyzed to test the framework performance and demonstrate its novel and practical capabilities.
  • ItemOpen Access
    Ultrasonic and acoustic pulse velocity methods for non-destructive detection of early decay in wood poles
    (Canadian Science Publishing, 2021-03-13) Tallavo, Fernando J.; Pandey, Mahesh D; Cascante, Giovanni G; Lara, Cristobal Abraham
    Wood poles are widely used to support overhead distribution and transmission power lines in North America and the world. These poles are vulnerable to internal deterioration due to extreme weather conditions, requiring a large number of poles to be inspected every year. This paper presents a comparative study of four stress wave-based nondestructive testing methods commonly used for condition assessment of wood poles. These include the traditional approaches of sounding, sonic pulse velocity, and ultrasonic pulse velocity tests; and a new approach that considers the orthotropic characteristics of wood, uncertainties in the elastic properties, ultrasonic wave velocity and attenuation. Two poles with an internal hole of 4\% of the cross-section are evaluated and compared by each method. Ultrasonic measurements of wave velocity and attenuation considering orthotropic characteristics of wood and uncertainties in the elastic properties provide a reliable wave-based NDT method for the detection of early decay in wood poles.
  • ItemOpen Access
    Assessment of a wastewater stabilization pond system for removal of arsenic, iron, and ammonia from reverse osmosis water treatment plant residual wastewater
    (Canadian Science Publishing, 2021-10-04) Bull, Harrison; Ekhlasi Nia, Ali; Asadi, Mohsen; McPhedran, Kerry
    Drinking water treatment plants (DWTPs) produce wastewaters with elevated concentrations of heavy metals, metalloids, ammonia, and other contaminants. These wastewaters require treatment via processes including wastewater stabilization ponds (WSPs). This study assessed the arsenic (As), iron (Fe), and ammonia (NH3) concentrations in a Saskatchewan DWTP WSP system of five sequential ponds. Drone imaging combined with flow and depth data was used to estimate retention times which increased from 7-9 to 8-10 days after the DWTP upgrade. Concentration trends showed Fe decreased from Pond 1 to 3 and increased in Ponds 3 and 5, while As decreased from Pond 1 to 5. Average effluent As concentrations of 10.6 g/L were over the 5.0 g/L guideline, while both Fe and NH3 concentrations guidelines were easily met post-upgrade in 2020. Several actions are recommended to ensure adequate WSP operation including dredging, aeration, and installing macrophytes capable of As uptake.
  • ItemOpen Access
    Review of “Hydraulic Engineering of Dams” by Willi H. Hager, Anton J. Schleiss, Robert M. Boes, and Michael Pfister
    (Canadian Science Publishing, 2021-11-23) Micovic, Zoran
    No abstract. This is a book review.
  • ItemOpen Access
    Fuzzy Analytic Hierarchy Process Framework for Quantifying the Flood Resilience of Housing Infrastructure Systems
    (Canadian Science Publishing, 2021-04-30) Sen, Mrinal Kanti; Dutta, Subhrajit; Golam, Kabir; Laskar, Shamim Ahmed
    Housing constitutes a basic need for all living beings. Unfortunately, natural hazards, including floods, pose a severe threat to housing infrastructure systems. In turn, this paper develops a framework to quantify the resilience of housing infrastructure systems against flood hazards. The parameters for this resilience are based on the literature and knowledge from experts. This paper gauges the significance of each resilience parameter is evaluated using the analytic hierarchy process (AHP) and the fuzzy AHP. The evaluated values are then compared to observe the effectiveness of fuzzy AHP over AHP. The evaluated importance of each parameter will help stakeholders focus on the most important parameters and, in turn, boost the flood resilience of infrastructure. This paper then implements the developed framework in a study area to quantify local flood resilience. This resilience value will help stakeholders in the considered area to understand the resilience of local housing infrastructure.