Engineering Commons^™

Numerical Modelling Of Downburst Interaction With Bluff Body, Aditi Jog

Electronic Thesis and Dissertation Repository

The objective of this study is to investigate the interaction of a bluff body with a downburst flow. Numerical investigation of the flow field using CFD analysis was carried out for three different downburst sizes (h/d=1, 2, 4) under suitable boundary conditions subjected to constant jet velocity. The downburst-structure interaction study was conducted for two jet diameters (h/d=1 and 4) and two radial locations from the downburst center.

The results showed that the downburst size greatly dominates the intensity of the flow. The largest downburst resulted in the highest velocity magnitude near the ground and also covered a larger area …

Numerical And Experimental Analysis Of Retrofit System For Light-Framed Wood Structures Under Wind Loading, Ryan B. Jacklin

Electronic Thesis and Dissertation Repository

Past high speed wind events have exposed the vulnerability of the roof systems of existing light-framed wood structures to the uplift forces resulting from high speed winds, contributing greatly to economic and human loss. This research focuses on developing a retrofit system to increase the uplift capacity of these structures using numerical and experimental techniques. The proposed system provides the uplift forces an alternate load path to the ground, reducing the demand placed on the weak, nailed connections within the structure. A three-dimensional finite-element model of a roof system of full-scale wood structure has been developed. The model is compared …

Finite Element Analyses Of Single-Edge Bend Specimens For J-R Curve Development, Yifan Huang

Electronic Thesis and Dissertation Repository

The fracture toughness resistance curve such as the J-integral resistance curve (J-R curve) is widely used in the integrity assessment and strain-based design of energy pipelines with respect to planar defects (i.e. cracks). Two studies about the development of the J-R curve are carried out and reported in this thesis. 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 the single-edge bend (SE(B)) specimen is developed based on the three-dimensional (3D) finite element analysis (FEA). The main …

Second-Order Analysis Of Cable-Stayed Bridge Deck Slabs, Zachary Mcneil

Electronic Thesis and Dissertation Repository

Current provisions in CSA S6-06 “Canadian Highway Bridge Design Code” for computing second-order effects in slender concrete beam-columns were derived for columns in buildings, where these effects can often be neglected, so their applicability to extremely slender cable-stayed bridge decks warrants investigation. The research reported in this thesis first reviews the provisions in CSA S6-06, as well as eight equations proposed by others, for computing the flexural rigidity, EI, of slender concrete beam-columns. Methods for quantifying the rotational restraint provided at deck slab supports by steel or concrete floorbeams are presented and validated: steel floorbeams provide negligible restraint but …

Capacity Assessment Of A Transmission Tower Under Wind Loading, Thomas G. Mara

Electronic Thesis and Dissertation Repository

Transmission towers play a vital role in power distribution networks and are often subject to strong wind loads. Lattice tower design is often based on a linear elastic response to wind loading using methodology derived for atmospheric boundary layer (ABL) winds. A number of failures have been attributed to high intensity wind (HIW) events such as downbursts and tornadoes. This thesis investigates extreme winds on a self-supported lattice transmission tower and ultimately makes comparisons of the capacity under ABL and HIW. The force-deformation relation between the base shear and the displacement of the tip of the tower are used to …

Stochastic Simulation Of Multiple-Station Ground Motions And Its Applications, Taojun Liu

Electronic Thesis and Dissertation Repository

Approaches to simulate single- and multiple-component multiple-station ground motion records with target spatial coherency and spatial correlation structures are developed for scenario events in this study. To develop the approaches, spatial correlation of the Fourier amplitude spectrum for a random orientation and for two orthogonal directions is assessed, and empirical equations are suggested. Moreover, spatial coherency of ground motions for two orthogonal horizontal directions is estimated using actual records from seven seismic events. Empirical coherency function is suggested for the components of records in two orthogonal horizontal directions at single and multiple recording stations. It was also found that the …

Prediction Of Wind Loads On Tall Buildings: Development And Applications Of An Aerodynamic Database, Bernard Kim

Electronic Thesis and Dissertation Repository

The Western University Aerodynamic Database (WAD) has been developed as an alternative means for structural engineers to estimate the preliminary design wind loads on tall buildings. The database consists of aerodynamic loads obtained from either the force-balance or pressure model tests on 56 tall buildings in their simulated actual surroundings carried out in the Boundary Layer Wind Tunnel Laboratory at Western University. The data for a given building include the statistics of the normalized aerodynamic loads such as the means, root-mean squares, and power spectral density functions of the base bending moments in two orthogonal directions and base torque. To …

Concrete Bridge Girders With Exposed Flexural Reinforcement, Trevor K. Scott

Electronic Thesis and Dissertation Repository

Reinforced concrete highway bridge girders are regularly repaired by replacing deteriorated concrete with new concrete, temporarily exposing the flexural reinforcement. The absence of bond between the concrete and steel at this stage makes it difficult to compute the flexural capacity and the current code criteria provide no guidance to assist practitioners.

The research reported in this thesis rectifies this knowledge gap. A thorough examination is presented of experimental and analytical investigations by others to determine the typical behaviour, including probable failure modes, of reinforced concrete specimens with exposed flexural reinforcement. Based on these findings, two analytical approaches are developed to …

Simplified Tools For Performance-Based Design Of Reinforced Concrete Frames Exposed To Fire, Salah El-Din F. El-Fitiany

Electronic Thesis and Dissertation Repository

Fire safety of Reinforced Concrete (RC) buildings is an important design aspect that ensures structural integrity during fire events. As new codes are moving towards performance based design, practitioners are in need of rational design tools to assess the strength and serviceability of individual RC elements and the structure as a whole during fire. This thesis provides such tools for RC frames.

A previously developed sectional analysis method is extended to cover RC beams subjected to fire from three sides. An extensive parametric study is conducted to evaluate the equivalent stress-block parameters at elevated temperatures.

A novel method to track …

Precast Deck Joints Using Frp And Ultra-High Performance Concrete, Augustine K. Banson

Electronic Thesis and Dissertation Repository

The need for rapid construction or replacement of highway bridge decks can be addressed by precast concrete elements reinforced with Glass Fiber Reinforced Polymer (GFRP) bars with cast-in-place joints made using Ultra-High Performance Concrete (UHPC). This thesis investigates the bond between GFRP bars and UHPC and splice length optimization to obtain narrow joints and simplified bar geometries. Multiple linear regression analyses of existing bond data indicate that the bar’s Young’s Modulus and embedded length are the most significant parameters that influence the average bond strength of sand-coated GFRP bars in UHPC: increasing either decreases the average bond strength. Linear-elastic uncracked …