Engineering Commons^™

Behavior Of Wind Turbine Towers And Blades Under Tornado Wind Fields, Mohamed Abugazia

Electronic Thesis and Dissertation Repository

The installation rate of wind turbines around the world is increasing significantly. Therefore, wind turbine farms are constructed in plentiful wind resources areas that put a considerable number of wind turbine towers under severe wind conditions. As a result, failures due to unexpected wind loads on either the blades or the tower are increasing. In addition, wind turbines are designed to resist synoptic wind loads as per the current guidelines, which do not consider high-intensity wind (HIW) events such as tornadoes. The built-in-house numerical code “HIW-WT” has been developed in this study to model wind turbines under three-dimensional wind fields …

Experimental Simulation Of Tornado-Like Vortices And Their Impact On High-Rise Buildings, Arash Ashrafi

Electronic Thesis and Dissertation Repository

One of the most crucial research areas in wind engineering is tornadoes due to the widespread damages to infrastructure and the environment in North America and other parts of the world. The proper scaling of tornadoes in experimental facilities, generating tornado-like vortices (TLVs) is, therefore, an essential part of evaluating tornado-indued damages on engineered buildings. The capability of producing TLVs of length scales in the range between 1:300 and 1:150 inside the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University has already been demonstrated using only one mode of the full potential of this simulator. A new mode …

Active Fluids: Rheological Properties And Response To Light Of Suspensions Of Synechocystis Sp. Cpcc 534, Zahra Habibi

Electronic Thesis and Dissertation Repository

Despite our current understanding of active fluid mechanics, more knowledge is required to fully understand their rheological properties, response to light, and details of the interactions between cells in diluted suspensions.

The focus of this thesis is on investigating the rheological properties of suspensions of cyanobacterium Synechocystis sp. CPCC 534 under shear, induced by stirring. Experiments were conducted at different stirring rates and results are compared with the stationary condition. A notable increase in growth and biomass of Synechocystis sp. under various shear conditions was observed and the yield was nearly doubled. Besides, the data showed Newtonian behavior for suspensions …

Crack Self-Healing In Alkali-Activated Materials: From Mechanisms To Strategies For Enhancing The Healing Efficiency, Lei Zhang

Electronic Thesis and Dissertation Repository

The increasing concern for decarbonizing concrete manufacturing is calling for sustainable construction materials since portland cement production contributes about 8% of global anthropogenic carbon dioxide emissions. Alkali-activated materials (AAMs) have emerged as promising alternative binders to curb carbon dioxide emissions from portland cement production and allow more sustainable construction. In addition, AAMs have desirable mechanical properties and high resistance to acidic and sulphate attacks.

Like conventional concrete, AAMs are quasi-brittle materials with low tensile strength, demonstrating susceptibility to cracking. Cracking-initiated deteriorations such as reinforcing steel corrosion, sulphate attack, and freeze-thaw damage, pose severe threats to the service life of concrete …

Estimation Of Tropical Cyclone Rain Hazard For Sites In Coastal Region Of Mainland China, Jiyang Gu

Electronic Thesis and Dissertation Repository

China experiences heavy national-wide rainfall events with distinct regional and seasonal characteristics. The tropical cyclones (TCs) originating from the Pacific ocean could cause intense rainfall along the coastal region of mainland China. Besides the severe rainfall, tropical cyclones could also cause high winds, storm surges, and large waves. Increasing direct economic loss is always caused by these tropical cyclones.

The mapping of TC wind hazard for the coastal region in mainland China could be carried out using the wind field model and empirical TC track model. The commonly used TC wind field models employed in TC wind hazard assessment are …

A Case Study On Medium And High Rise Timber Buildings, Moustafa El-Assaly

Electronic Thesis and Dissertation Repository

Heavy timber is the upcoming and rising star in the construction industry in the European and north American market. However, this topic is yet to be discovered. Light frame wood LFW has been used for decades but was always restricted to certain limits. Limits that heavy timber can overcome easily. In this thesis, topics related to the application of heavy timber in the construction of buildings are searched. First, a comparative study based on the Canadian market discussing the alternatives heavy timber can offer such as glulam and cross laminated timber (CLT) in comparison with LFW when applied to mid-rise …

Uncertainties In Internal Pressure Of Oil Pipelines And Implications For The Reliability Analysis, Yue Liu

Electronic Thesis and Dissertation Repository

The internal pressure is the most important operational load for oil and gas pipelines. The maximum operating pressure (MOP) is the maximum pressure the pipeline is qualified to be operated according to a given standard. In deterministic fitness-for-service (FFS) assessment of in-service pipelines containing flaws such as corrosion defects and cracks, the remaining pressure containment capacity of the pipeline is evaluated and compared with MOP multiplied by a factor of safety to determine if immediate rehabilitation actions for the pipeline are necessary. However, the actual internal pressure of an in-service pipeline is however uncertain and fluctuates with time. Due to …

Implication Of City Growth On Wind-Induced Loads For Cladding And Structural Design, Hadil M. Abdallah

Electronic Thesis and Dissertation Repository

As cities grow, the urban topology changes in density resulting in continuous variations in wind flow. The interaction of flow with this changing surrounding environment drives the aerodynamics to become more complex and varying, subjecting the building to significant changes in wind-induced-loads both on structural and non-structural elements. In this study, a series of boundary layer wind tunnel tests are conducted to investigate the impact of city growth on cladding and structural loading by using a typical tall building adopted from the Commonwealth Advisory Aeronautical Council (CAARC) building model. The city growth is represented by five different generic surrounding configurations, …

A Partial-Turbulence Approach To Estimate Peak Wind Loads On Low-Rise Building Roofs, Yitian Guo

Electronic Thesis and Dissertation Repository

Quasi-steady (QS) theory is a commonly-used tool in wind engineering for the assessment of wind loads on structures induced by large-scale gusts. However, the QS-based approach tends to underestimate peak loads significantly since it fails to capture the effects of small-scale and body-generated turbulence. The objective of this thesis is to develop a method to estimate peak wind loads on low-rise roofs based on a partial-turbulence approach, i.e., using the QS vector model for loads induced by large-scale fluctuations from the incident flow, and a separate statistical model to account for the effects due to body-generated turbulence.

Wind tunnel tests …

Full-Scale Field Study Of A Geogrid-Reinforced Unpaved Road System, Abdalla El Tawati

Electronic Thesis and Dissertation Repository

Geogrids are widely used to improve the performance of unpaved roads constructed over weak subgrade. However, the behavior of geogrids under traffic loads and their reinforcing mechanisms, as well as the resulting benefits to the roadway performance are not well understood. A full-scale field study was conducted to quantify the effectiveness of geogrids in unpaved roads, evaluate their reinforcing mechanism, and identify which geogrid properties are most directly related to performance improvement. Ten full-scale unpaved road test sections were constructed with varying relevant parameters including geogrid aperture shape, geogrid tensile modulus, and thickness of the base course layer. Five of …

Finite Element Analysis Of Buckling Capacity Of Conical Steel Tanks Considering Field-Measured Initiation Imperfections – A Case Study, Haoyi Zhang

Electronic Thesis and Dissertation Repository

The geometric imperfection in elevated steel conical water tanks is a key factor that influences the buckling capacity of the tank. Current considerations of imperfections in the design of conical tanks are based on theoretical analysis, whereby the imperfection shapes and locations are assumed to have the most critical impact on the capacity. This thesis investigates the initial imperfections of an actual stiffened liquid-filled steel conical tank (LFCT) based on high-resolution laser scan measurement data of the tank geometry.

In the first part of this study, detailed analyses of the laser scan data were carried out to extract the global …

Experimental Study Of Tornado-Induced Pressures, Aya Kassab

Electronic Thesis and Dissertation Repository

The increased devastation associated with tornadic flow-fields in terms of human lives or destruction of properties and their subsequent economic losses highlights the significance of understanding the tornado vortex structure, particularly near the ground where the majority of this destruction happens. While the body of research in this area is increasing there is a lack of resolution associated with physical near-surface measurements in tornado-like vortices (TLVs) and the effects of translation, surface roughness, and surface vortex dynamics are not yet well understood.

In order to address these gaps, high spatial and temporal surface pressure measurements were carried out at WindEEE …