Civil Engineering

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Open Access
Dynamic Parking Pricing using Transaction Data
(2024-11-07) Luo, Wenhan; Nourinejad, Mehdi
Managing on-street parking in dense urban areas poses challenges due to high demand and limited parking space availability, leading to increased congestion and search times for drivers. This thesis explores the efficacy of implementing a dynamic parking pricing policy inside a parking network to mitigate these challenges. Dynamic parking pricing adjusts prices based on parking demands, aiming to balance parking occupancy across different areas. The research investigates the feasibility of utilizing transaction data to predict parking occupancy, eliminating the need for expensive occupancy detection infrastructure. A predictive Neural Network is generated, and a price-setting algorithm is proposed to optimize and change parking prices to increase availability in high-occupied areas and attract drivers to underutilized spaces.
Open Access
Towards an improved understanding of the importance hydrologically diverse data for training flood forecasting models
(2024-11-07) Snieder, Everett Joshua; Khan, Usman T.
Floods constitute a major threat to populations and infrastructure. Flood frequency and severity are projected to increase due to factors such as climate change and urbanisation. Flood early warning systems (FEWS), which rely on models that predict streamflow, provide relevant groups (e.g., transportation authorities, police, schools, etc.) with advance notice of flood risk, allowing them to respond early and minimise flood damage. However, Canada has inadequate flood forecasting infrastructure and lacks a national system. To address the projected flood risk, there is a crucial need to improve modelling capabilities in Canadian watersheds. The following manuscript-based dissertation presents a series of case studies that propose methodological improvements to hydrological modelling frameworks, focusing on the selection of training data for flood forecasting studies. The studies also demonstrate applications of machine learning (ML) to improve model accuracy and reliability. These studies span a wide range of spatiotemporal conditions, ranging from forecasting flash-flooding at sub-hourly frequencies in small urban watersheds, to nationwide, multi-day forecasts. Each of the four studies exploits the benefits of hydrologically diverse training data for improving model performance as FEWS. The first manuscript introduces a novel ensemble model framework for traditional, physics-based urban stormwater models. The method leverages the concept of equifinality to generate ensembles with diverse parameter value estimates, which are shown to outperform traditionally calibrated models. The second and third manuscripts evaluate pure ML-based ensembles. The second manuscript simplifies flood forecasting by framing it as a binary problem. The Synthetic Minority Oversampling TEchnique (SMOTE) algorithm is applied to increase the proportion of flood samples in the dataset, which is shown to improve flood forecast accuracy at the expense of an increased number of false positives. Next, three ensemble algorithms and five classifiers are systematically compared; extreme learning machines (ELMs) and support vector machines (SVMs) are found to be the strongest classifiers. The third manuscript proposes an improvement to popular ensemble algorithms, which consists of embedding synthetic oversampling within the ensemble loop, to increase the covariance of ensemble member predictions. The fourth manuscript evaluates a novel cluster-based training data selection framework for regionally trained deep learning models. The method is used to show how data from hydrologically dissimilar basins is more useful to improving performance in a target basin, compared to data from the target basin itself, or proximal basins. Collectively, the results of these studies advance techniques for achieving improvements in model performance, especially during high streamflow conditions, which are most important to flood warning systems.
Open Access
Optical Detection of Azithromycin in Water and Urine Using Molecularly Imprinted Polymer-Microfluidics Integration
(2024-11-07) Noha Mohamed Hosny Hasaneen; Brar, Satinder Kaur; Rezai, Pouya
Azithromycin (AZM) is one of the most used antibiotics worldwide. Monitoring its concentration in urine and water is essential to control the spread of antibiotic-resistant bacteria. Two new methods for AZM analysis in artificial urine were developed using fluorescence-based microscopic and spectrophotometric techniques after forming an ion-pair complex with fluorescein isothiocyanate. The fluorescence method showed higher sensitivity and precision, with a linear range of 0-31.25 µg/mL, LOD of 0.41 µg/mL, and LOQ of 1.23 µg/mL, compared to the spectrophotometric one. Moreover, it showed a narrower recovery range of AZM from artificial urine samples, indicating higher precision in complex matrices compared to the spectrophotometric one. For enhanced selectivity and portability, a study on integrating molecularly imprinted polymer (MIP) as synthetic receptor inside a microfluidic device with the fluorescence-based detection method was performed. Despite the challenges with specificity, the study constitutes a promising detailed investigation where both extraction and detection of AZM can be done on the same platform using optical techniques. This approach can be potentially extended to enable multiplexing, where a microfluidic device with multiple channels, each containing an MIP specific for a different target compound can be used.
Open Access
Nonlinear Seismic Assessment Criteria for Reinforced Masonry Structures in Canada
(2024-11-07) Calcagno, Marco; Pantazopoulou, Stavroula
The objective of this thesis was to bridge the knowledge gap that exists in the assessment of reinforced masonry structures in Canada under seismic loading. Despite the seismic risk present in Canada, there is no formally approved seismic risk-based assessment framework for existing RM structures, and instead, U.S. evaluation criteria (NIST, ASCE/SEI - 41, TMS 402) are used for the assessment of structures built to the Canadian design code (CSA S304). The work presented in this thesis aims to validate the extension of the ASCE/SEI-41 codes to the Canadian context through the development of a comprehensive database of over 70 reinforced masonry walls built and tested in Canadian Academic Institutions. Code-based analytical values of strengths, stiffness, mode of failure, and drift capacities, were compared with the experimentally recorded values and reported failure patterns.
Open Access
Investment and Financing of Roadway Digital Infrastructure for Automated Driving
(2024-11-07) Ahmadian Shahreza, MohammadAmir; Nourinejad, Mehdi
Connected automated vehicles (CAVs) rely on sensors to scan their environment, enabling efficient decision-making, though their limited range poses challenges. Enhancing CAV operations by leveraging cooperative sensing via vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications offers ways to improve autonomy. This study examines optimal investments in vehicular connectivity and stationary sensor deployment under different traffic conditions. Our results highlight the trade-off between roadside stationary sensors and CAV-mounted sensors. Results show that for low traffic flow and constrained budgets, infrastructure investment is preferable, while higher traffic flow favors connectivity among CAVs. Additionally, the analysis shows that an optimal toll cannot fully cover digital infrastructure costs, though if safety benefits are factored in, covering the costs of constructing such infrastructure becomes feasible. The self-financing theorem also holds for the case of digitalization of existing roads if their flow-capacity ratio exceeds a certain threshold.
Open Access
The Use of Instrumented Capillary Rise Experiments with Time-Domain Reflectometry to Determine Capillary Rise and Soil Salinity in Real-Time
(2024-11-07) Samoon, Urooma; Bashir, Rashid
The movement of saltwater in soils through capillary rise poses a concern, given its potential to affect both soil structure and hydraulic properties. This emphasizes the critical necessity of real-time monitoring to accurately measure and assess the salt concentration in the soil. Time-Domain Reflectometry (TDR) can be used to simultaneously measure the volumetric water content and bulk electrical conductivity of soil over time. Bulk electrical conductivity serves as a valuable metric for estimating pore water electrical conductivity, providing a basis for establishing a correlation with the salt concentration in the soil. Capillary rise experiments, instrumented with TDR probes, were conducted to measure the volumetric water content and bulk electrical conductivity of two distinct sand grades (30/40 and 40/50). These experiments encompassed a series of trials involving varying concentrations of salt solutions, juxtaposed with a control test utilizing deionized water. Further batch testing was conducted using the same sands to establish empirical relationships between bulk electrical conductivity and soil pore water concentration. The time series data, encompassing experimental volumetric water content and concentration from the capillary rise experiment, was used for inverse modelling to estimate soil hydraulic and solute transport properties. The findings from this study indicate that TDR provides accurate results for water content and electrical conductivity in column capillary rise experiments. The results also suggest that TDR observation data coupled with inverse modelling provides a soil water characteristic curve comparable to that measured using an evaporation method with the use of HYPROP. The outcomes of this study offer valuable insights into comprehending the intricate dynamics of water and salt within soil systems.
Open Access
Understanding the impact of the scavenging capacity on costs of the UV chlorine advanced oxidation process for drinking water treatment using the external calibration method and the development of cost curves.
(2024-11-07) Lima-Thompson, Reece Curtis; Gora, Stephanie
UV-driven advanced oxidation processes (e.g. UV/H2O2, UV/Cl) that couple UV irradiation with oxidizing chemicals to generate highly reactive species such as ·OH radicals and reactive chlorine species are increasingly being recommended for the removal of recalcitrant organic contaminants in drinking water and wastewater. Establishing the doses of UV and oxidant required to achieve treatment objectives is challenging because many species besides the contaminant(s) of interest exert a scavenging capacity for the highly reactive species generated in advanced oxidation processes. Overall, the aim of this research was to establish whether a colour-based test developed to measure the hydroxyl radical scavenging capacity of water samples could be adapted to measure the scavenging capacity of reactive chlorine species in addition to hydroxyl radicals. The results were used to estimate the cost implications of installing a UV/H2O2 or UV/Cl reactor in a drinking water treatment plant. Initial capital and ongoing operational and maintenance cost curves were developed to characterize the potential cost savings of utilizing the method to treat a well-known contaminant of concern.
Open Access
Investigating Bisulfide Sorption onto Bentonite through Laboratory Experiments and Numerical Modelling
(2024-11-07) Papry, Sifat Azad; Krol, Magdalena
The long-term performance evaluation of the Canadian deep geologic repository (DGR) relies significantly on bentonite clay, a crucial material in the engineered barrier system. One safety concern is microbiologically influenced corrosion of the used fuel containers (UFCs) which may occur if bisulfide (HS-) transports through the bentonite buffer to the UFC surface. HS- sorption onto bentonite can reduce the corrosion risk, but its dynamics are not yet well-understood, especially in DGR environments. Hence, this study offers a comprehensive insight into HS- sorption process onto bentonite through extensive laboratory experiments and numerical modelling. First, a robust methodology was developed to build confidence in the experimental procedure. Subsequently, six sets of batch experiments (including desorption tests) were performed as a function of temperature (10-40°C), contact time (1-120 hours), liquid to solid mass ratios (L:S) (100-1000), initial HS- concentration (1-6 mg L-1), pH (9-11), and ionic strength (0.01 M-1 M NaCl). The experimental results indicated that HS- sorption onto bentonite occurred faster, and the equilibrium sorption capacity increased (by 3%) with increasing temperature. However, sorption decreased with increasing pH and ionic strength. Several established kinetic and isotherm models were applied to the experimental data to provide insight into HS- sorption dynamics onto bentonite. In addition, desorption test results indicated that HS- was irreversibly sorbed on bentonite. Surface analyses conducted using scanning electron microscopy along with energy dispersive spectroscopy, suggested that sorption might have occurred due to chemical reactions of HS- with the iron (Fe) present in bentonite. Lastly, a thermodynamic-based sorption model was developed in PHREEQC assuming that sorption was driven by three key processes: (i) redox reaction with the structural Fe3+ sites, (ii) surface precipitation as iron sulfide, FeS (likely mackinawite), and (iii) surface complexation reactions with surface hydroxyl group (OH) at the edge sites of montmorillonite. The model successfully described the experimental trends and provided valuable insights into the relative contribution of each process to the total sorption mechanism. Altogether, this study provides novel insights from experimental and numerical modelling that enhance the understanding of HS- sorption onto bentonite, which supports the Canadian DGR design and other nuclear repositories worldwide.
Open Access
Evaluation of the Flexural Response of Steel Reinforced UHP-FRC Beams Using Distributed Sensing
(2024-10-28) Giuseppe Domenico Garisto; Butler, Liam; Pantazopoulou, Stavroula
The interaction between ultra-high-performance fibre-reinforced concrete (UHP-FRC) and steel reinforcement significantly affects the displacement ductility of UHP-FRC beams in flexure, leading to a brittle failure mechanism due to crack localization. Previous studies faced limitations in fully exploring this interaction due to conventional sensors. Distributed fibre-optic sensors (DFOS), particularly based on optical frequency domain reflectometry (OFDR), offer new insights. In our study, DFOS and strain gauges monitored strains along longitudinal reinforcement and support wire during four-point loading tests on beams with varying fibre contents (1% and 3%) and reinforcement ratios (1.5% and 2.3%). Results showed that lower fibre content and higher reinforcement ratio led to greater ductility, indicated by increased curvature and strain peaks. Finite element modelling underestimated experimental responses, suggesting a need for improved material property characterization.
Open Access
The Electric Cargo Cycle Routing Problem: An Enhanced Approach with Predictive Battery Performance
(2024-07-18) Garcia Santana, Adonai Manace; Gingerich, Kevin
This thesis explores the optimization of electric cargo cycles (ECCs) for urban logistics, focusing on battery performance and routing efficiency. By analyzing two ECCs under different operational scenarios, a novel Electric Cargo Cycle Battery (ECCB) model is developed for battery performance forecasting. This extends to the creation of the Electric Cargo Cycle Routing Problem (ECCRP), an adaptation of the capacitated vehicle routing problem, and its Enhanced version (E-ECCRP), incorporating battery constraints and the flexibility of battery swapping. Comparative analysis of these models reveals the benefits of integrating battery performance into routing strategies, underscoring ECCs' role in eco-friendly urban logistics. This research offers valuable insights into electric mobility utilization for sustainable city transport solutions, providing a foundation for optimizing ECC usage in urban environments.
Open Access
Development of a Kinetically Engineered Microbial Community for Nitrite Shunt as a B-Stage Process Using Different Aeration Strategies
(2024-03-16) Soliman, Moomen Mahmoud Moharram Abdallah; Eldyasti, Ahmed K.
Nowadays, depleted energy resources, increasing worldwide energy demand and global climate change has been witnessed. In accordance, wastewater treatment plants (WWTPs) have prioritized minimizing its energy use, maximizing resources recovery, while efficiently treating the received wastewater. Shortcut BNR (SBNR) has been proposed as an energy-efficient nutrients removal process towards lowering the energy use of the current WWTPs. Nonetheless, full-scale implementation of SBNR in mainstream conditions has been hindered by the major challenge of nitrite oxidizing bacteria (NOB out-selection. To address such a key bottleneck, this dissertation proposes, for the first time, a novel kinetic-adaptation based strategy to engineer the microbial community to maintain NOB out-selection at mainstream conditions. The successful implementation of such a strategy and its underlying mechanisms was demonstrated and investigated for more than 400 days. In result, an ammonia removal efficiency of 99.4±0.4% and nitrite accumulation rate of 87.4±0.6% under low DO levels of 0.1–0.2 mg/L was reached. Afterwards, the potential to employ the developed strategy to perform mainstream nitrite shunt was investigated considering the limited carbon availability in the A-stage effluent, its fractionation, and the applied aeration strategy. At carbon to nitrogen (C:N) ratio as low as 6.0, ammonia, COD and total inorganic nitrogen (TIN) removal efficiencies of 99.2±0.7, 94.0±0.1 and 93.2±1.6% were successfully achieved under continuous low DO aeration strategy. Investigations revealed that maintaining NOB suppression played a key role in achieving high TIN without the need for external carbon addition. Two more aeration strategies were investigated, low DO intermittent aeration and high DO intermittent aeration. At C:N ratio as low as 6, higher TIN removal of 95.8±0.9% was achieved at low DO compared to high DO which achieved a TIN removal of 73.8±1.7%. Therefore, it was concluded that the developed kinetic-adaptation strategy can be utilized along with different aeration strategies with slight advantage to low DO intermittent aeration for its higher TIN removal with limited carbon. The findings of this dissertation present a novel strategy that blaze a trail to overcome the major bottleneck of NOB out-selection to implement nitrite shunt at mainstream as energy and resources efficient B-stage process.
Open Access
Understanding Freight Fluidity in Peel Region with Emphasis on Arterial Roads
(2024-03-16) Jain, Prateek; Park, Peter Y.
This thesis examines the concept of freight fluidity and seeks to analyze the correlation between truck collisions and freight fluidity measures in the Region of Peel. The study employed a multidisciplinary approach, incorporating data processing, visualization, and correlation techniques. The research involved developing a dashboard that depicts freight fluidity measures and truck collisions. A descriptive data analysis was conducted to identify trends related to freight fluidity measures and collisions. The maximum congestion for trucks was observed in the afternoon period. Brampton showed the highest level of congestion and collisions among all the municipalities. By statistically analyzing the correlation between freight fluidity measures and truck collisions, the study provided insights into how freight fluidity can lead to safer and efficient freight transportation. A statistically significant correlation was observed between collisions and freight fluidity measures. The findings of this thesis will provide valuable insights for transportation planners in the Region of Peel.
Open Access
Performance Assessment and Retrofit Strategies for Unreinforced Masonry Structures
(2024-03-16) Pezeshki, Mina; Pantazopoulou, Stavroula
This research project provides a detailed investigation into the seismic assessment of Unreinforced Masonry (URM) heritage structures, emphasizing their cultural and historical importance and vulnerability to earthquakes. It focuses on advanced seismic evaluation methods, including 3-D finite element modeling, to address specific challenges such as the unique characteristics of these buildings, like distributed stiffness and mass, and the absence of diaphragm action. The project aims to bridge knowledge gaps in the dynamic, nonlinear behavior of URM structures during seismic events, and involves comparative evaluation of different computational modeling methods. Additionally, it addresses the calibration and validation of computational models, analysis of dynamic response and failure characteristics, and evaluates retrofitting strategies to mitigate seismic risks. The research aligns with international preservation conventions and aims to contribute to the effective seismic risk mitigation strategies for unreinforced masonry heritage buildings.
Open Access
Experimental Investigation on Microplastics Biofouling Rate in an Aquatic System
(2024-03-16) Mohammadiun, Malihe; Karimpour, Shooka; Brar, Satinder
Microplastics (MPs), small plastic particles under 5 millimeters, are a growing environmental concern in freshwater and marine ecosystems. They originate from numerous sources, can easily move due to their small size, and hold the potential to transport pollutants through their movements in marine and freshwater ecosystems. Hence, formulating the distribution and movement of these microplastics within aquatic environments is very important. However, MP distribution and mobility in water are complex processes which depend on many environmental and physical factors. One of the factors contributing to the dynamic nature of microplastics is biofouling. Biofouling, a process where MPs undergo surface changes and accumulate microorganisms, is a key factor influenced by factors like size, shape, and environmental conditions. Water quality in Lake Ontario is impacted by urban and wastewater discharge and across the lake MPs are reported at different levels. The wastewater effluent influences biofilm formation on MPs and in turn, affects their movement in the lake. Despite increased research on microplastic biofouling in freshwater, a significant research gap still exists especially in experimental works. To address this gap, in this study, a series of lab-based experiments, simulating Lake Ontario conditions, were conducted to analyze bacterial growth and biofilm formation on different microplastic sizes. The study investigated factors such as bacteria type, nutrient availability, shaking speed, microplastic size, and flow rate on MP biofouling formation and growth. This study highlights the significance of biofouling on microplastics, focusing on how bacterial competition, nutrient supply, and the rate of water flow affect the formation of biofilms. This understanding is crucial for addressing hydro-environmental issues related to biofouling and microplastics, providing insight into mitigation measures.
Open Access
An analysis of 100 years of post-fire streamflow responses of British Columbia watersheds
(2024-03-16) Abogadil, Karen Elaine; Khan, Usman T.
Wildfires are becoming larger and more severe due to climate change. This trend is destructive to the forest ecosystem, disrupting many eco-hydrologic processes in forested watersheds. Effects can include rapid runoff responses, increased surface runoff, and elevated erosion, leading to lower water quality and long-lasting effects on hydrologic ecosystem services (such as flood regulation). However, post-fire hydrology studies often have variable and contrasting results, making cross-study comparisons difficult. Studies are typically short-term and focused on single wildfire events. This research aims to determine accurate indicators for post-fire flow responses. The study area includes 257 drainage basins (grouped into five ecozones) in British Columbia, Canada, known for its susceptibility to wildfires and floods. The study analyzes wildfire data from 1910 to 2020. Post-fire percent changes for four hydrological metrics (low, high, peak flows and runoff ratio) were calculated using pre-fire and post-fire values for multiple temporal bands. Using streamflow, precipitation, temperature, wildfire perimeters, and topographic data, statistical analyses including hypothesis testing and multiple linear regression were done. The two-sample Kolmogorov-Smirnov test results comparing the fire group against the two control groups resulted in highly variable p-values. Multiple linear regression was done to predict the percent changes for all flows. Regression yielded poor model performance, suggesting that the hydrometeorological parameters alone cannot explain the post-fire changes observed. The most frequently influential watershed indicators in post-fire streamflow responses were percent burn, maximum daily temperature, and elevation. Results across multiple temporal bands, ecozones and hydrological metrics over 100 years will aid future research on the wildfire effects on hydrology in forested watersheds.
Open Access
Analysis of Drinking Water Distribution Systems using the Engineering Design Process
(2024-03-16) Moghaddam-Ghadimi, Sara; Gora, Stephanie
Our research has identified that issues pertaining to distribution infrastructure are a leading cause of water safety vulnerability. These challenges are exacerbated within small communities which experience a disproportionate number of boil water advisories compared to larger communities. This study used the engineering design process to explore the root causes and potential solutions to water safety hazards within the water distribution system. A systematic literature review thoroughly examined data-backed evidence of issues causing potential threats to drinking water safety. Potential solutions involving the implementation of distributed treatment using UV LEDs installed at different points in the distribution system were identified through research and stakeholder consultation and compared to one another using EPANET software. The results of this analysis indicated that installing UV LEDs at the point-of-entry could potentially be used to reduce the impact of water safety hazards within the distribution system.
Open Access
Optimizing Truck Parking Facilities with Major Distribution Centres in Pandemic Conditions
(2024-03-16) Annalingam, Elanakayon; Park, Peter; Gingerich, Kevin
The Covid-19 pandemic has had a disproportionate impact on truck drivers facing inadequate rest space availability due to exacerbated by pandemic conditions. GPS data is used in this thesis to understand trends of freight parking and the critical locations in which freight activity is occurring. The data is also used to compare pre-pandemic patterns in 2019 with pandemic conditions in 2020. An optimization scheme is developed using a P-median approach to optimize travel from rest areas to major distribution centres. This scheme identifies the best locations where truck drivers can park and rest before accessing distribution centres. It is also proposed to be used to identify top locations for potential expansion for rest areas. The Region of Peel is used as the study area for this analysis as a major freight centre and documented impact from the Covid-19 pandemic.
Open Access
Biodegradation of Perfluorocarboxylic Acid in Landfill Leachate
(2024-03-16) Shu, Xuhan; Brar, Satinder K.
Long-chain perfluoro carboxylic acids (LC-PFCAs), a subset of perfluorochemicals (PFCs), were identified in landfill leachate during the sampling period from June 2022 to July 2023. In this thesis, the exclusive focus is on the chemical degradation of PFCAs, omitting biological degradation experiments due to their persistent nature. The leachate analysis revealed a seasonal fluctuation in its chemical characteristics including nitrogen, phosphate, alkalinity, pH, and chemical oxygen demand (COD). Interestingly, the selected C9 and C10 LC-PFCAs were consistently present in the leachate but did not show any significant seasonal variation. Concentrations of LC-PFCAs ranged from 100 ng/L to 800 ng/L. To assess the biodegradability of C9 and C10 PFCA in the leachate using native microorganisms, a bench-scale experiment was conducted. The microbial community exhibited biphasic growth when exposed to the specified PFCAs (10-100 mg/L) for 6 days. Notably, the C9 and C10 PFCAs displayed a biodegradation efficiency of up to 58% within this 6-day period.
Open Access
Spatialized probabilistic flood risk assessment in urban areas protected by levees
(2024-03-16) Mainguenaud, Florence Marianne; Khan, Usman T.; Sharma, Jit
Flood hazard assessment is a necessary input to a flood risk assessment. Integrated flood hazard assessment methods provide a good overview and distinguish three steps: assessment of the flooding event probability, reliability assessment of the flood defense system, flood propagation using numerical simulations. Flood hazard assessment results in one or several flood maps, each dependent on the intensity and duration of the modeled flooding event. A definition of flood risk assessment is the combination of hazard, exposure, and vulnerability. We identified several gaps in each step of the flood risk assessment process. Gaps found in flood hazard assessment include: the lack of decisive method to estimate a combined levee failure probability of various failure mechanisms and few probabilistic flood hazard assessments include levee failure scenarios. One of Integrated Flood Risk Management (IFRM) aims is to provide a standard for risk assessments to enable comparisons between different studies and better management on the long run. To address those gaps, we propose a method, which estimate earthen levee failure probabilities for several return periods and failure mechanisms (backward erosion, slope stability, and overflow). We used limit equilibrium method and Monte-Carlo simulations to estimate sliding failure, compared seepage gradients to a critical gradient to estimate backward erosion failure, and used expert judgment to estimate overflowing failure probabilities. We aggregated failure mechanism probabilities into a global fragility curve using Monte-Carlo simulations, hence providing a comprehensive fragility curve for an earthen levee segment. We defined several scenario of flood and levee failure for backward erosion and overflowing mechanisms to compute a probabilistic flood hazard map. We modeled six flood events, each challenging the levee reliability, enabling the breaching of each levee segment. For each scenario, the resulting flood maps of water depth and velocity are associated with a flood occurrence probability and a levee failure probability. The maps are combined into a single probabilistic flood hazard map where for each pixel, a cumulative probability curve of depth and velocity is available. Future works will propose a probabilistic flood risk map building on the probabilistic flood hazard method, and applying new vulnerability considerations.
Open Access
Numerical Evaluation of Square Reinforced Concrete Slabs Incorporating High Volumes of Recycled Materials
(2024-03-16) Ikpotokin, Peace Osalumhense; Butler, Liam J.
Concrete remains the most widely used building material in the world, due to its locally available constituent materials, versatility of form and shape, functionality, and durability. However, due to the processes involved in the manufacturing of cement, the sustainability of concrete both globally and in local communities, is often called into question. Cement production accounts for approximately 7 percent of CO2 emissions globally and, as the resources required for concrete production (e.g., aggregates, sand, potable water, etc.) continue to diminish, this poses a series problem for the long-term viability for the concrete construction industry. A three-pronged solution to this problem is therefore required which focuses on reducing, reusing, and recycling our concrete infrastructure. As urban populations are only expected to increase in the coming decades, concrete structures will continue to be constructed. This research is aimed at investigating the flexural response of two-way slabs produced using low-carbon concrete (LCC) containing recycled and secondary materials. Given that concrete floor slabs account for the largest portion of concrete in a typical building, the use of LCC in slabs has the potential to have a significant reduction in the structure’s overall CO2 footprint. The primary objective of this research is to examine the effects of replacing portland cement with high volumes of slag, fine and coarse recycled concrete aggregates (RCAs). To address the main research objective, a three-phase experimental program was completed. The first phase involved the material characterization of the various constituent materials including cement, slag, natural sand, natural coarse limestone aggregates, and fine and coarse RCAs. The second phase focused on concrete mixture design development. An experimental matrix included the batching and testing of several low carbon concrete mixtures consisting of one target strength class (30 MPa) and combinations of up to 100% replacement of natural limestone and sand with fine and coarse RCAs and up to 50% replacement of portland cement with ground granulated blast furnace slag. The next phase of experimental testing program was then completed to help better understand the individual and combined effects of the various constituent materials on fresh (e.g., slump, density, air content) and hardened concrete properties (e.g., compressive and splitting tensile strength) of low carbon concrete. Based on the top performing concrete mixtures, the third phase incorporated their measured material properties into a finite element model. Four two-way slabs (one control slab and three slabs containing different LCC mixtures) were then analyzed to evaluate and compare the maximum flexural capacity, deformational characteristics, and crack patterns. The obtained flexural and deformation response of the slabs were then compared with results obtained from the yield line analysis, Response 2000 sectional analysis which is based off the moment capacity and results were compared to CSA empirical code equations. Findings showed that firstly, the predicted pattern of failure from the finite element analysis was in concordance with that of the yield line analysis, secondly an inverse relationship between density LCC and the replacement ratio of recycled/secondary materials was obtained, and thirdly, that 50% of the numerical deflection values were in alignment with ACI crossing beam method. In terms of flexural capacity, relatively low decreases in load of 4.6%, 8.7%, and 9.8%, were computed for LC-C, LC-CF, LC-CFS, respectively. These results are promising for demonstrating the feasibility of utilizing LCC incorporating high volumes of recycled and secondary materials in two-way slab systems.