Engineering Commons^™

Bi-Directional Cyclic Behaviour And Liquefaction Analysis Of A Silica-Carbonate Sand, Keyvan Mirbaha

Electronic Thesis and Dissertation Repository

The cyclic behavior and liquefaction behavior of reconstituted samples of a local silica-carbonate sand are examined by performing monotonic and cyclic simple shear tests in addition to bender element shear wave velocity measurements. Shear wave velocity was found to vary with effective overburden stresses by an average power of 0.25. Maximum shear modulus (G_max) was also computed from the shear wave velocity measurements and a correlation was developed between G_max, effective stress and void ratio. Small strain and cyclic strain dependent shear modulus of the soil were determined, and shear modulus reduction curves were obtained. The …

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 …

Pressure Equalization Of Wind-Induced Pressures On Residential Vinyl Siding Cladding In Full-Scale, Randy A. Van Straaten

Electronic Thesis and Dissertation Repository

Residential vinyl siding cladding system failures have been observed in high wind events. North American vinyl siding design standards allow a 64% pressure equalization factor, which yield relatively low wind load resistance for these products. The allowance is based on testing, which is questioned based on the literature review. The modified discharge equation analytical model, developed by others, accurately predict extent of pressure equalization found in scaled wind tunnel measurements. The model provides value in informing testing standards, product design and forensic investigations. However, it has only been validated based on scaled wind tunnel testing which may present scaling effect …

Estimation Of Turbulence Effects On Wind-Induced Suctions On The Roof Of A Low-Rise Building, Chieh-Hsun Wu

Electronic Thesis and Dissertation Repository

The effects of turbulence in the atmospheric boundary layer (ABL) on surface pressures of a typical low-rise building roof are investigated in this thesis. A 1/50 geometrically-scaled model of the Texas Tech University Wind Engineering Field Research Lab (WERFL) building model is used for pressure measurements in wind tunnel experiments. ABL wind turbulence intensities ranging from about 10% to 30%, and length scales ranging from 6 to 12 times of the building height (H) are generated. The effects of ABL turbulence on the mean roof pressures within the separated flow are explained from the time-averaged Navier-Stokes equations. The pressure fields …

Static And Dynamic Properties Of Controlled Low-Strength Materials Incorporating Treated Oil Sands Waste, Ahmed Mneina

Electronic Thesis and Dissertation Repository

Controlled Low-Strength Materials (CLSM) is a self-compacted self-leveling cementitious material with compressive strength of 8.3 MPa or less. It is used as an alternative of soil backfill materials in geotechnical and infrastructure applications. This study investigates the effects of incorporating treated oil sand wastes (TOSW) as a partial replacement of sand or fly ash on fresh and hardened properties of CLSM. In addition, the environmental impact of the proposed new mixtures was evaluated. The results show that CLSM mixtures incorporating TOSW had satisfied the limits and requirements of ACI committee 229 for CLSM with no environmental hazards. The incorporation of …

Tensile And Impact Behaviour Of Shape Memory Alloy Fibre Reinforced Engineered Cementitious Composites, Mohamed Ali El-Sayed Mahmoud Ali

Electronic Thesis and Dissertation Repository

Extreme loading events such as impact, blast, and earthquakes have often led to partial or total collapse of structures, associated with economic and human life loss. Therefore, civil engineers have been seeking innovative materials and systems that would allow designing resilient and smart structures which can withstand such catastrophic events. Recently, engineered cementitious composites (ECC) and shape memory alloys (SMA) have emerged as strong contenders in the production of smart and resilient structural systems.

The aims of this study are to explore the possible synergy between ECC and SMA for developing a novel hybrid fibre-reinforced ECC incorporating randomly dispersed SMA …

System Reliability Analyses And Optimal Maintenance Planning Of Corroding Pipelines, Changqing Gong

Electronic Thesis and Dissertation Repository

The failure of corroding pipeline joints may induce severe consequences. However, maintenance is expensive due to the cost of excavating and repairing a single joint and typically a significant number of joints that need repair. It is central to develop an optimal cost-effective maintenance strategy that balances cost and safety. A key component of the strategy is the reliability based condition evaluation of pipeline joints. The focus of the research reported in this thesis is therefore developing efficient reliability assessment methods for pipeline individual joints, and developing an optimal maintenance framework for the entire pipeline system.

First, efficient system reliability …

Liquefaction Assessment Of Carbonate-Silica Silty Sands Using Energy, State Parameter And Shear Wave Velocity, Naemeh Naghavi

Electronic Thesis and Dissertation Repository

The liquefaction behaviour and dynamic properties of reconstituted natural carbonate-silica silty sand samples were investigated in a series of monotonic and cyclic triaxial tests. The critical state parameters of the mixtures with different levels of fines were obtained through monotonic triaxial compression tests. Bender element tests were performed at the consolidation stage to characterize soil’s initial state and small strain properties. The results demonstrated that soil contraction capacity, liquefaction potential and undrained brittleness increase by increasing the state parameter. A general correlation between shear wave velocity and state parameter was established. The susceptibility and triggering of liquefaction under cyclic loading …

Estimation Of Cavity Pressures In Air-Permeable, Multi-Layer Systems Using A Lumped-Leakage Approach, Rahul Prabhakaran Nair Sreedevi

Electronic Thesis and Dissertation Repository

For conventional buildings, the proper estimation of wind-induced pressures on the external façade, the roof surface, or the net pressures across elements like a canopy or parapet, which are exposed to wind on both sides, can be easily done using conventional wind tunnel tests. But in the case of air-permeable multi-layer systems, which have gaps or porosity in the external layer along with a cavity between the external and inner layers, the estimation of wind loading across the external layer or in the inner cavity by wind tunnel tests can be quite difficult due to practical difficulties in exactly simulating …

Wall Pressure Coefficients For Low- To High-Rise Buildings, Emilio S. Hong

Electronic Thesis and Dissertation Repository

Currently, the design of wall cladding and components are based on provisions provided in building codes, such as ASCE 7 for the United States. These codes provide pressure coefficients based on the tributary area, position on the building and the building category. For ASCE 7, low-rise and high-rise buildings are separated by an artificial boundary at 60 ft. (18.2 m). The reasoning for this artificial boundary is unclear. This work investigates the wall pressure coefficients for various buildings, based on aspect ratios, motivated by the large differences in design pressure coefficients for low-rise and high-rise buildings.

For this study, a …

Uncertainty Modeling In The Assessment Of Climate Change Impacts On Water Resources Management, Sohom Mandal

Electronic Thesis and Dissertation Repository

Climate change has significant impacts on water resource systems. The objective of this study is to assess climate change impacts on water resource management. The methodology includes (a) the assessment of uncertainty introduced by choice of precipitation downscaling methods; (b) uncertainty assessment and quantification of the impact of climate change on projected streamflow; and (c) uncertainty in and impact of climate change on the management of reservoirs used for hydropower production. The assessment is conducted for two future time periods (2036 to 2065 and 2066 to 2095). The study area, Campbell River basin, British Columbia, Canada, consists of three reservoirs …

Effects Of Turbulence On The Separating-Reattaching Flow Above Surface-Mounted, Three-Dimensional Bluff Bodies, Abul Fahad Akon

Electronic Thesis and Dissertation Repository

Investigations of separated and reattaching flows over three-dimensional bluff bodies in turbulent boundary layers are important because of the large aerodynamic loads that these flows cause. For example, roofs of low-rise buildings are vulnerable to this kind of wind loading. Turbulence in the upstream flow affects the pressure distributions and the mean size of separation bubbles formed on bluff body surfaces. Whereas a number of studies have focussed on two-dimensional separation bubbles and surface pressures, a comprehensive understanding of the surface pressures and the separating-reattaching flows in relation to the turbulence in the incident boundary layers for surface-mounted, three-dimensional bluff …

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 …