Engineering Commons^™

Heat Of Hydration Thermal Performance And Flexural Capacity Of Stainless-Steel Reinforced Concrete Sections, Mokhtar Khalifa

Electronic Thesis and Dissertation Repository

Stainless steel (SS) is increasingly used in the construction field due to its high strength and corrosion resistance. However, its coefficient of thermal expansion is different from that of concrete. This difference raises concerns about the potential for concrete cracking during the hydration process. To address this concern, a thermal-structural finite element model was developed to predict the stresses in SS reinforced concrete (RC) sections during the hydration process. Different curing regimes were taken into consideration. The analysis was performed in two stages. First, a transient thermal analysis was performed to determine the temperature distribution within the concrete section as …

Seismic Performance Of Reinforced Concrete Frames Retrofitted Using External Superelastic Shape Memory Alloy Bars, Yamen Ibrahim Elbahy, Maged A. Youssef, Mohamed E. Meshaly

Civil and Environmental Engineering Publications

Pre-1970s designed and built reinforced concrete frame structures are considered unsafe when subjected to seismic loads. Insufficient anchorage of the beam reinforcement in the beam-column joints of these structures is considered a main deficiency. Newly built frame structures are seismically designed for safety, where high inelastic deformations can occur under moderate to strong earthquakes. Minimizing these inelastic deformations makes the structure repairable. One way to minimize these residual deformations is by using smart materials such as superelastic shape memory alloys (SMAs). In this paper, the seismic performance of RC frames retrofitted using external superelastic SMA bars is investigated and compared …

Aversion And Warning Factors For Assessing Existing Reinforced Concrete Structures, Marcie Van Weerdhuizen

Electronic Thesis and Dissertation Repository

In a world of aging infrastructure, sustainability initiatives require additional investment in the assessment of existing reinforced concrete structures. Reliability-based assessment should minimize costs by reducing conservatism, while ensuring levels of safety equivalent to those for new designs. Current Canadian and US provisions assign target reliability levels for structural assessment based on criteria including occupancy type, expected failure behaviour, and the effect of element failure on the overall structural integrity. These criteria are defined using discrete and qualitative parameter values. It is shown that the true structural conditions can be better represented by verifying the applicability and completeness of these …

Quantification Of Uncertainties In Inline Inspection Data For Metal-Loss Corrosion On Energy Pipelines And Implications For Reliability Analysis, Tammeen Siraj

Electronic Thesis and Dissertation Repository

One of the major threats to the oil and gas transmission pipeline integrity is metal-loss corrosion. Pipeline operators periodically inspect the size of the metal loss corrosion in a pipeline using in-line inspection (ILI) tools to avoid pipe failure which may lead to severe consequences. To predict pipe failure efficiently, reliability-based corrosion management program is gaining popularity as it effectively incorporates all the uncertainties involved in the pipe failure prediction. The focus of the research reported in this thesis is to investigate the unaddressed issues in the reliability-based corrosion assessment to assist in better predicting pipe failure.

First, a methodology …

Eco-Efficient Preplaced Recycled Aggregate Concrete Incorporating Recycled Tire Waste Rubber Granules And Steel Wire Fibre Reinforcement, Saud A. Alfayez

Electronic Thesis and Dissertation Repository

With increasing world population and urbanization, the depletion of natural resources and generation of waste materials is becoming a considerable challenge. As the number of humans has exceeded 7 billion people, there are about 1.1 billion vehicles on the road, with 1.7 billion new tires produced and over 1 billion waste tires generated each year. In the USA, it was estimated in 2011 that 10% of scrap tires was being recycled into new products, and over 50% is being used for energy recovery, while the rest is being discarded into landfills or disposed. The proportion of tires disposed worldwide into …

Flexural Behaviour Of Reinforced Concrete Elements Retrofitted Using External Unbonded Superelastic Shape Memory Alloy Bars, Yamen Ibrahim Elbahy

Electronic Thesis and Dissertation Repository

Steel reinforced concrete (RC) framed structures are seismically designed for safety, where the earthquake energy is dissipated through yielding of the steel bars. During strong earthquakes, high inelastic deformations are allowed to take place. This allowance results in significant residual deformations. Thus, following an earthquake, the structure might be deemed irreparable, requiring its demolishing and replacement. If the frame can be designed to regain its original shape following an earthquake, then the structure will be repairable. This kind of design can be achieved by using smart materials such as Shape Memory Alloys (SMAs).

SMAs have unique properties, which make them …

Design And Probabilistic Analysis Of Mid- And High-Rise Wood Buildings Subjected To Earthquake Excitations, Shucheng Yang

Electronic Thesis and Dissertation Repository

Mass timber products, such as the glulam or cross laminated timber (CLT), are less frequently used construction materials at present for mid-rise and high-rise buildings. The feasibility and possible advantages of applying timber materials for constructing mid- and high-rise buildings are under investigation. One of the issues that needs to be addressed for the use of heavy timber materials is the safety of such constructions under seismic excitations. To address this issue, the nonlinear inelastic seismic responses and capacity curves of a wood buildings must be assessed. For this, the 10-, 15- and 20-storey buildings are designed using heavy timber …

Experimental And Numerical Investigation Of Emulative Connections In Precast Concrete Walls, Mohamed Gamal Elsayed

Electronic Thesis and Dissertation Repository

Grouted connections are widely used in the precast concrete construction. For instance, in precast concrete walls, they are used to connect assemblies of vertically stacked panels. The connection is comprised of a grout cylinder bound by a corrugated metallic duct, which is used to house a large diameter reinforcing bar bridging the horizontal gap of stacked panels. The connection is used to provide vertical continuity to the assembly, and to help resist tensile demands from in-plane bending. Current design guidelines consider such connections through a bar-in-concrete treatment, disregarding its composite nature and the confinement effect of the duct. This has …

Condition Assessment Of Concrete Bridge Decks Using Ground And Airborne Infrared Thermography, Tarek Omar

Electronic Thesis and Dissertation Repository

Applications of nondestructive testing (NDT) technologies have shown promise in assessing the condition of existing concrete bridges. Infrared thermography (IRT) has gradually gained wider acceptance as a NDT and evaluation tool in the civil engineering field. The high capability of IRT in detecting subsurface delamination, commercial availability of infrared cameras, lower cost compared with other technologies, speed of data collection, and remote sensing are some of the expected benefits of applying this technique in bridge deck inspection practices. The research conducted in this thesis aims at developing a rational condition assessment system for concrete bridge decks based on IRT technology, …

Seismic Fragility Assessment Of Superelastic Shape Memory Alloy Reinforced Concrete Shear Walls, Emad A. Abraik, Maged A. Youssef

Civil and Environmental Engineering Publications

Mitigation of seismic damage can be achieved through self-centering techniques. One of the potential techniques involves the use of Superelastic Shape Memory Alloy (SE-SMA) bars in Reinforced Concrete (RC) structures. This study explores the use of such bars in the plastic-hinge regions of RC walls. The seismic performance and vulnerability of SE‑SMA RC walls of ten- and twenty-story buildings are analytically assessed using fragility curves. The maximum inter-story drift, residual drift, and fragility are evaluated using multi strip analysis. The results clearly demonstrate the superior seismic performance of SE-SMA RC walls as compared to steel RC walls.

Seismic Performance Of Modular Steel Frames Equipped With Shape Memory Alloy Braces, Papia Sultana, Maged A. Youssef

Civil and Environmental Engineering Publications

The demand for modular steel buildings (MSBs) has increased because of the improved quality, fast on-site installation, and lower cost of construction. Steel braced frames are usually utilized to form the lateral load resisting system of MSBs. During earthquakes, the seismic energy is dissipated through yielding of the components of the braced frames, which results in residual drifts. Excessive residual drifts complicate the repair of damaged structures or render them irreparable. Researchers have investigated the use of superelastic shape memory alloys (SMAs) in steel structures to reduce the seismic residual deformations. This study explores the potential of using SMA braces …

A Performance Based Design Approach For Tall Buildings Under Wind Loading, Fouad Y. Elezaby

Electronic Thesis and Dissertation Repository

The wind design of buildings is typically based on strength provisions under ultimate loads. This is unlike the ductility-based approach used in seismic design, which allows inelastic actions to take place in the structure under extreme seismic events. This research investigates the application of a similar concept in wind engineering. In seismic design, the elastic forces resulting from an extreme event of high return period are reduced by a load reduction factor. A load reduction factor is chosen by the designer and accordingly a certain ductility capacity needs to be achieved in the structure. Two reasons have triggered the investigation …

Assessment Of Dynamic Effect Of Transmission Line Conductor Longitudinal Reaction Due To Downburst Loading, Ibrahim Ibrahim

Electronic Thesis and Dissertation Repository

Due to the locality and non-stationary nature of downburst wind loading events, their effect on the structural response of transmission line structures is of special nature that differs from conventional atmospheric boundary layer wind loading. Acknowledging such difference, the current thesis aims to quantify the dynamic effect associated with downburst loading on transmission line systems. To achieve that, several steps had to be realized, including experimentally verifying the numerical model used for analysis using wind field that was generated using computational fluid dynamics. The verified model was extended from model scale to full scale, where the wind field used for …

Investigation Of Ductile Crack Growth And Normalization Method For Se(T) Specimen Using Finite Element Analyses, Cheng Qian

Electronic Thesis and Dissertation Repository

The fracture toughness resistance curve (e.g. J-R curve) is widely used in integrity assessment and strain-based design of oil and gas pipelines with respect to planar defects (i.e. cracks). This thesis includes two-dimensional (2D) and three-dimensional (3D) finite element analyses (FEA) of ductile crack growth of X80-grade pipeline steel based on the Gurson-Tvergaard-Needleman (GTN) constitutive model, and investigation of the normalization (NM) method to generate the J-R curve for the single-edge tension (SE(T)) specimen.

First, the GTN model implemented in the computational cell is adopted in the commercial software ABAQUS to calibrate the micromechanical parameters for the pipeline steel. Subsequently, …

Partial Material Strength Reduction Factors For Aci 318, Tong Zhang

Electronic Thesis and Dissertation Repository

The strength reduction factors, phi, defined in ACI 318-14 for different structural actions and elements lead to inconsistent results. This study proposes partial material strength reduction factors for concrete, phi_c, and reinforcing steel, phi_s, that yield similar design strengths and more consistent reliability indices. Three structural actions are investigated: moment; shear; and, combined moment and axial force. The first-order, second-moment method is used to compute reliability indices for moment and shear, and Monte Carlo simulation is used for combined moment and axial force. The statistical parameters assumed for the professional factor for shear strength significantly impact …

Behaviour Of Pre-Stressed Concrete Transmission Poles Under High Intensity Wind, Ahmed M. Ibrahim

Electronic Thesis and Dissertation Repository

Among different types of electrical transmission line structures, pre-stressed concrete transmission poles have the advantages of low installation and maintenance costs, appropriate delivery time, and high corrosion resistivity. Typically, these poles are designed to resist synoptic wind loading. Current design codes do not consider the effect of high intensity wind (HIW) events in the form of downbursts and tornadoes on pre-stressed concrete poles despite the fact that those weather events are the main cause of failure of transmission line structures. The first comprehensive study conducted to assess the behaviour of pre-stressed concrete transmission poles under HIW is presented in this …

Seismic Performance Of Steel Helical Piles, Moustafa K. El-Sawy

Electronic Thesis and Dissertation Repository

Recent earthquakes have highlighted the need for safe and efficient construction of earthquake resilient structures. Meanwhile, helical piles are gaining popularity as a foundation for new structures and retrofitting solution for existing deficient foundations due to their immense advantages over conventional driven pile alternatives. In addition, helical pile foundations performed well in recent earthquakes, proving they can be a suitable foundation option in seismic regions. The objective of this thesis is to evaluate the seismic performance of helical piles by conducting full-scale shaking table tests and nonlinear three-dimensional numerical modeling using the computer program ABAQUS/Standard. The experimental setup involved installing …

Analysis Of Framing Failures In Wood-Frame Residential Roofs Under Wind Load, Sarah A. Stevenson

Electronic Thesis and Dissertation Repository

Wood-frame residential roof failures are among the most common and expensive types of tornado damage. Hip roofs are commonly understood to be more resilient during extreme wind in relation to gable roofs. However, inspection of damage survey data from recent tornadoes has revealed a previously unstudied failure mode in which hip roofs suffer partial failure of the framing structure. This research focuses on proving the concept of framing failures in hip roofs. Evidence of partial framing failures and statistics of their occurrence are explored and discussed, and common roof design and construction practice is reviewed. Two-dimensional finite element models are …

Numerical And Experimental Analysis Of A Retrofit System For Light-Framed Wood Structures Under Wind Loading, Joshua D. Rosenkrantz

Electronic Thesis and Dissertation Repository

the sheathing and rafters, and toenail connections between the rafters and stud walls. However, these connections have poor resistance to uplifting forces, as occurs in high wind speed events, causing sheathing or roof-to-wall-connection (RTWC) failures. The improvements made to building codes after Hurricane Andrew affected only new construction, and the economic losses caused by roof failures in homes built prior to 1993 from Hurricane Katrina pointed to a need to retrofit older structures. This paper will investigate the design, analysis, and testing of a temporary cable-netting roof harness as an alternative to other relatively expensive and invasive retrofitting options. To …

Bim Assisted Design Process Automation For Pre-Engineered Buildings (Peb), Mohammad Delavar

Electronic Thesis and Dissertation Repository

The effective adoption and implementation of Building Information Modeling (BIM) is still challenging for the construction industry. However, studies and reports show a significant increase in the rate of BIM implementation and adoption in mainstream construction activities over the last five years. In contrast, Pre-Engineered Building (PEB) construction, a specialized construction system which provides a very efficient approach for construction of primarily industrial buildings, has not seen the same uptake in BIM implementation and adoption. The thesis reviews the benefits and the main applications of BIM for the PEB industry as well as challenges of its practical implementation. To facilitate …

Numerical Modeling Of Tornado-Like Vortex And Its Interaction With Bluff- Bodies, Zoheb Nasir

Electronic Thesis and Dissertation Repository

The study the flow structure of tornado-like vortices and their impact over engineering structures is important due to the extent of tornado induced fatalities and damages observed each year in North America and around the world. In the present study, a numerical modeling approach inspired by the WindEEE Dome and the modified version of Ward’s Tornado Simulator has been developed. Using a full-scale numerical simulator, tornadoes of different intensities have been simulated for different swirl ratio values to study flow structures in comparison with previous studies. The effect of topographic features on the tornado-like vortex has been investigated for the …

Shape Memory Alloy Reinforced Concrete Frames Vulnerable To Strong Vertical Excitations, M A. Elfeki, Maged A. Youssef

Civil and Environmental Engineering Publications

Reinforced concrete (RC) framed buildings dissipate the seismic energy through yielding of the reinforcing bars. This yielding jeopardizes the serviceability of these buildings as it results in residual lateral deformations. Superelastic shape memory alloys (SMAs) can recover inelastic strains by stress removal. This paper extends previous research by the authors that optimized the use of SMA bars in RC frames considering the horizontal seismic excitation by addressing the effect of the vertical seismic excitation. A steel RC six-storey building designed according to current seismic standards is considered as case study. Five different earthquake records with strong vertical components are …

Ductile Corrosion-Free Gfrp-Stainless Steel Reinforced Concrete Elements, Maged A. Youssef, Mohamed E. Meshaly, Ahmed Elansary

Civil and Environmental Engineering Publications

Corrosion of steel rebars is known to cause deterioration of concrete structures that can lead to catastrophic failures. To mitigate this problem, steel rebars can be replaced with Glass Fiber-Reinforced Polymer (GFRP) rebars. However, the lack of ductility of GFRP-reinforced elements has prevented their use in many structural applications, especially in seismic areas. Stainless Steel (SS) rebars are corrosion resistant and have adequate energy absorption and ductility. However, they are much more expensive than steel rebars. This paper proposes the combined use of SS and GFRP rebars to achieve ductile and corrosion-free elements. The first challenge for such a proposal …

Investigation Of Grouted Dowel Connection For Precast Concrete Wall Construction, Douglas J. Provost-Smith

Electronic Thesis and Dissertation Repository

The grouted dowel connection is a simple and cost-effective connection used in many precast concrete structural systems. The required dowel length is currently designed as a regular bar in reinforced concrete, which underestimates the bond strength, thus resulting in excessive connection lengths. Furthermore, precast wall construction continues throughout cold weather, where in-situ heating of the grout used in the grouted dowel connections is usually conducted for short periods of time. Hence, early-age exposure to subfreezing conditions may affect the quality of the grout and subsequently the bond strength of the connection, which can compromise structural integrity.

In this thesis, full-scale …

Development Of Design Loads For Transmission Line Structures Subjected To Downbursts Using Aero-Elastic Testing And Numerical Modeling, Amal Elawady

Electronic Thesis and Dissertation Repository

The failure of transmission line structures due to severe High Intensity Wind (HIW) events is one of the major problems facing the electrical utility companies in various places around the globe including Canada. An extensive research program focusing on this problem started about fifteen years ago at The University of Western Ontario (UWO). In this Thesis, two major milestones are achieved leading to the advancement of the knowledge in this field. The first milestone is conducting, for the first time, a test on an aero-elastic model of a multi-span transmission system under reduced–scale simulated downbursts. The first objective of the …

Behavior Of Fire-Exposed Rc Frames Before And After Jacketing, M. Monir M. Ajan Alhadid

Electronic Thesis and Dissertation Repository

Analysis and design of fire-exposed Reinforced Concrete (RC) frames before and after jacketing with concrete layers are commonly performed using prescriptive methods that rely on the concept of fire rating. These methods were developed based on empirical results on individual RC members subjected to certain fire conditions. In typical fire scenarios, the residual capacity, stiffness and thermal deformations affects not only the local performance of each fire-exposed member, but also the load redistribution and global behavior of the entire frame. In terms of fire safety, the philosophy of the new building codes considers objective-based design as an alternative of the …

Enhancing The Seismic Performance Of Steel Structures Utilizing Superelastic Shape Memory Alloys, Papia Sultana

Electronic Thesis and Dissertation Repository

Although conventional earthquake-resisting structural systems provide the life safety level during earthquakes, they experience significant structural damage when exposed to strong ground shaking that render structural retrofitting as uneconomical. Superelastic shape memory alloys (SMAs) can be used in steel structures to reduce the residual deformations due to their recentering capability, which can facilitate post-seismic retrofitting. The primary aim of this thesis is to enhance the seismic performance of both regular and modular steel structures using an optimum amount of superelastic SMAs material in terms of maximum inter-storey drift, residual drift, and damage scheme.

First, a simplified method based on pushover …

Numerical Studies For Improving Fracture Toughness Resistance Curve Testing Using Single-Edge (Notched) Tension Specimens, Yifan Huang

Electronic Thesis and Dissertation Repository

The fracture toughness resistance curve, i.e. the J-integral resistance curve (J-R curve) or the crack tip opening displacement resistance (CTOD-R) curves, is widely used in the integrity assessment and strain-based design of energy pipelines with respect to planar defects (i.e. cracks). This thesis deals with issues related to the experimental determination of the J(CTOD)-R curves using the newly-developed single-edge (notched) tension (SE(T)) specimens. In the first study, the plastic geometry factor, i.e. the η_pl factor, used to evaluate J in a J-R curve test based on …

Innovating Two-Stage Concrete With Improved Rheological, Mechanical And Durability Properties, Manal F. Najjar

Electronic Thesis and Dissertation Repository

Two-stage concrete (TSC), also known as preplaced aggregate concrete, is a special type of concrete that is produced using a unique procedure which differs from that of conventional concrete. TSC is distinguished by its high coarse aggregate content and exceptional placement technique, whereby aggregates are first pre-placed in the mold then injected with a special grout. The preplacement of aggregates saves substantial energy since only the grout needs mechanical mixing; the grout is self-leveling and needs no vibration and no mechanical compaction. However, TSC applications are still limited despite substantial advancement of modern concrete technology. Therefore, there is a need …

Mat-705: Improving The Efficiency Of Zinc Sacrificial Anodes In Repaired Concrete, Ahmed G. Bediwy, Mohamed T. Bassuoni, Martin Beaudette

Canadian Society for Civil Engineering

Zinc sacrificial anodes are considered an effective and economical method to prevent the electrochemical corrosion of steel bars by providing cathodic current to bars, which can provide corrosion protection at low galvanic current densities in the range of 0.2 to 2 mA/m2. Sacrificial anodes are commonly used in RC structures particularly in bridge decks to mitigate a critical phenomenon that occurs in the original concrete beside the repaired patches, which is known as the ‘halo effect’. One of the key factors affecting the efficacy of zinc anodes is the resistivity of concrete or cementitious repair material in which these anodes …