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Seismic Performance and Design of Steel Chevron and Split-X Braced Frames
No full textChevron and split-X steel concentrically braced frames (CBFs) are widely used as the lateral load-resisting system of buildings. Under seismic loading, lateral displacements tend to concentrate in one or a few storeys of such braced frames due to the poor hysteretic behaviour of their braces. This response can impose significant flexural demands on the columns, which may lead to the formation of plastic hinges in the presence of a large axial force and P-Δ effects. Furthermore, damage concentration may lead to brace low-cycle fatigue fracture due to significant axial deformation in the braces of the storeys experiencing large lateral deformations. Although chevron and split-X braced frames have been the subject of numerous studies in the past, their seismic design still requires further improvement, namely, seismic-induced demands on their beams and columns, influence of beam yielding on their seismic performance, moment ratio for stability design of their columns, brace loading scenarios for the design of beams, columns, connections and footing, and mitigation techniques for damage concentration should be addressed.
This M.Sc. research project aims to examine the seismic behaviour of moderately ductile (Type MD) chevron and split-X CBFs designed to the Canadian steel design standard, assess the adequacy of the seismic provisions in this standard, and propose improved seismic design methods with a focus on column flexural demands, brace-induced unbalanced forces on the beams, and mitigation of drift concentration. A wide range of CBFs are generated by varying key design parameters, representing potential design scenarios. A fibre-based numerical model is then developed to examine the seismic response of frames and create a database of CBF response through nonlinear response history analysis. Analysis results showed that lateral deformation concentrated in one or a few storeys, rather than being distributed as anticipated in the design. Peak response parameters obtained from dynamic analyses confirmed that the Canadian steel design standard may underestimate column moment demands, damage concentration may not be prevented despite strict design requirements, and brace loading scenarios specified in this standard may not accurately estimate brace unbalanced forces induced on the beams. New system-specific seismic design guidelines are proposed for chevron and split-X frames. These guidelines include new moment ratios for the stability design of columns, predictive equations to estimate column moment demands, relaxation on the total height of chevron braced frames with yielding beams, new brace loading scenarios for chevron frames with yielding beams and split-X frames to compute unbalanced brace forces on their beams, and a new method to identify the storey(s) susceptible to drift concentration and minimize potential drift concentration by adjusting the braced frame design
Dental Trauma Education Among North American Dental Schools: Results from Multi- Center Interviews with Dental Educators
Get PDFBackground/aims: The prevalence of traumatic dental injuries (TDI) in North America reaches
20–30% of the population. Studies highlight the inability of many general dentists to effectively
manage dental trauma (DT) cases. DT education at the predoctoral level varies globally, spread
across multiple disciplines, with little known about North American dental schools. This gap in
understanding could explain deficiencies in general dentists’ treatment of DT cases. This study
aimed to gain insights into the existing predoctoral DT education across North American dental
schools, identify gaps, and recommend improvements to refine and unify DT education.
Methods: Interviews were conducted with DT instructors and curriculum coordinators from North
American dental schools. A validated questionnaire was used for the interviews. Questions were
categorized into three sections: DT curriculum, student assessments, and clinical exposure during
predoctoral training. Qualitative data were analyzed individually and grouped for common
findings.
Results: The overall response rate was 62.6% (n=52) universities. Sixty-three instructors from 48
dental schools participated in the analysis. Four schools opted out of the study. DT education was
found to be fragmented in 47 schools, with a mean of 5.7±1.57 hours allocated to DT teaching.
Only nine schools tested students following DT coursework, and just one conducted a final
examination solely on DT. All instructors reported insufficient clinical exposure to DT cases
during rotations.
Conclusions: Significant deficiencies were reported by dental educators in relation to DT
education in North American dental schools. Limited clinical exposure and an inconsistent
curriculum may leave students ill-prepared for managing DT cases. Increased hands-on experience
and curriculum standardization across schools could improve DT education and preparedness
Failure Mode Prediction and Experimental Analysis of 2D Tubular Braided Composites with Twisted Fibers Using Stereo Digital Image Correlation
No full textTubular braided composites (TBCs) are useful and highly tailorable materials. They are fabricated
from the mixture of a textile yarn in a braided structure with a surrounding matrix material. These
resultant structures are strong under tension and allow the distribution of complex loads across the
braided textile material. Recently, textile twist was implemented into the structure of TBCs and
found to improve their mechanical stiffness and strength in tensile stress states. Conversely, TBCs
are generally weak in pure compression. This work seeks to begin exploratory work into the
implementation of textile twist in TBCs and whether it can serve to improve compressive
performance. Their compression has three distinct failure modes: Euler buckling, diamond shaped
buckling and micro buckling. These failure modes are based on geometric and material properties
and can be made into a shape efficiency map to predict the failure of different TBC structural
configurations. The configurations chosen herein were 1” inner diameter TBCs with 35°, 45° and
55° braid angles, with and without 5° yarn twist, and with and without graphene infused in the
epoxy. All configurations were predicted to fail due to diamond shaped buckling. The
configurations were then manufactured (except for the graphene infused epoxy) to experimentally
validate their failure mode and determine whether any mechanical improvements are attained. The
experiments were done using stereo digital image correlation for the strain measurements. The
samples failed due to the same mechanism as predicted. The elastic modulus and ultimate
compressive strength of the samples both decreased with the inclusion of textile twist as opposed
to untwisted samples. Furthermore, the stiffness decreased inversely to the braid angle for the
untwisted samples, albeit statistically insignificant. The 35° and 45° samples failed before fully
settling into the compression from the platens due to the increased stiffness of the yarns and the
reduced cover factor caused by the twisted yarns. Additional experimentation with samples having
cover factors near one would be beneficial to further our understanding of TBCs compressive
behaviour
Consequences of Morpheme Access During the Comprehension and Production of Three Types of Pseudo-Compounds
No full textDatasets and Stata analysis files for:
Gagné, C.L., Auch, L. & Spalding, T.L. (in press) Consequences of Morpheme Access During the Comprehension and Production of Three Types of Pseudo-Compounds. *Morphology*. Accepted 2025.08.19
Real-time Reinforcement Learning for Achieving Goals in Big Worlds
Get PDFIn this dissertation, I motivate the need for real-time learning and propose algorithms that can learn in real time. I argue that such algorithms are needed for achieving goals in large and partially observable environments---big worlds. I then present my algorithms, developed in collaboration with others, in two parts.
In Part I, I present algorithms that can learn quickly and reliably in the linear function approximation setting. I introduce an algorithm for learning temporal predictions---SwiftTD---and use it to develop an algorithm for decision-making---Swift-Sarsa. The key property of these algorithms is that they can learn with large step-size parameters online without the instability associated with quick online learning.
In Part II, I present algorithms for learning non-linear recurrent features efficiently. I introduce the idea of continual imprinting for generating useful candidate features, and I present an algorithm for efficiently computing the gradients of recurrent features online
Culture and Perception: Cultural Variation in Cognition and Self-Perception in European Canadians and Mongolians.
Get PDFStudies in cultural psychology have reported cultural variations in cognition and perception between Eastern and Western cultures. However, recent studies have given serious consideration to the "WEIRD" discourse, emphasizing the necessity of data from cultures that have been underrepresented. The current research focuses on Mongolians, representing Central Asia's nomadic pastoral culture, and contrasts them to European Canadian counterparts, representing Western sedentary cultures. Participants engaged in existing cognitive and perceptual tasks, which included (1) the framed line task, (2) the causal attribution task, (3) the self-inflation task, (4) the engaged/disengaged emotion task, (5) the culture of honor questionnaire, and (6) self-construal measures. The results indicated that the holistic tendency among Mongolians is higher than that of European Canadians. Still, the self-assertiveness was generally as strong as their European Canadian counterparts. The current study succeeded in gaining compelling patterns of findings that depict nomadic-pastoral people’s psychological minds in a limited number of existing findings. Finally, we discuss that the unique Mongolian patterns of independence and interdependence with holistic cognitive style may play an important role in portraying the nomadic mind and further developing cultural psychological theory beyond the East West dichotomy