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Stopper-Bearing System – A Solution to Displacement Control of Bridge DecksTsai, Yi-Te 2009 August 1900 (has links)
Bridges play an important role in society, especially during the post-earthquake
period that enables emergency vehicles and traffic for safe egress and ingress to
minimize the loss of property and life. However, some past earthquakes have resulted in
large horizontal displacements on the superstructure that have lead to unseating of bridge
spans and unexpected pounding forces that damaged critical components such as
bearings and anchor bolts. To this end, a new bearing system, referred to as a stopperbearing
system (SBS), is proposed as one solution to address the vulnerability of bridge
bearings and other components. The horizontal displacement of a deck can be limited to
a desired range using the SBS. The nonlinear load-deformation behavior of the SBS is
obtained from ABAQUS and used to define the SBS within reinforced concrete
analytical bridge models developed in SAP2000, which are subjected to the 1999 Chi-
Chi, Taiwan earthquake ground motion (1.01g - E-W component and 0.43g - N-S
component). The results from the nonlinear time history analyses show that the SBS is
effective in limiting bridge deck displacements and pounding effects. Preliminary analytical modeling of the SBS shows promise as a solution to displacement control of
bridge decks for overall enhancement of bridge performance during seismic events.
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Seasonal and Reproductive Effects on Wound Healing in the Flight Membranes of Captive Big Brown Bats (Eptesicus fuscus)Ceballos-Vasquez, Alejandra 01 December 2014 (has links)
Bats (Order Chiroptera) are the only mammals capable of power flight. The flight membranes of bats are not only essential for locomotion, but also play vital roles in homeostasis. Although understanding wound healing in the flight membranes of bats is important because injuries in the wild are common, with the recent emergence of white-nose syndrome, understanding wound healing in bat flight membranes has become even more important.
In order to conduct my studies on wound healing in the flight membranes of bats, it was necessary to manually restrain bats. In this thesis I present a novel bat restrainer that I designed and that reduces stress experienced by restrained bats during experimentation and data collection.
Wound healing is an energy dependent process, as such it is expected that wound healing times will vary during periods of energy constraint (i.e. hibernation) and/or at times of peak demand (i.e. lactation). However, previous studies on wound healing have only looked at healing at times when there are no energy constraints. In thesis I aimed to better understand the effects of seasonality and reproduction on wound healing. Using an 8 mm circular punch, I inflicted biopsy wounds to the chiropatagium of healthy captive big brown bats, Eptesicus fuscus. I compared wound healing times between winter and summer seasons, and between reproductive (i.e. lactating) and non-reproductive females. As expected, wound healing times were longer during the winter months when bats are conserving energy. On the other hand, reproductive status did not have an effect on wound healing times. Although most bats heal, I observed impaired wound healing. This finding is important because it is the first time that impaired wound healing is reported in healthy bats. / Thesis / Master of Science (MSc)
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Finite Element Analysis of the Application of Synthetic Fiber Ropes to Reduce Seismic Response of Simply Supported Single Span BridgesTaylor, Robert Paul 05 August 2005 (has links)
Movement of a bridge superstructure during a seismic event can result in damage to the bridge or even collapse of the span. An incapacitated bridge is a life-safety issue due directly to the damaged bridge and the possible loss of a life-line. A lost bridge can be expensive to repair at a time when a region's resources are most strained and a compromised commercial route could result in losses to the regional economy. This thesis investigates the use of Snapping-Cable Energy Dissipators (SCEDs) to restrain a simply supported single span bridge subjected to three-dimensional seismic loads. SCEDs are synthetic fiber ropes that undergo a slack to taut transition when loaded.
Finite element models of six simply supported spans were developed in the commercial finite element program ABAQUS. Two seismic records of the 1940 Imperial Valley and 1994 Northridge earthquakes were scaled to 0.7g PGA and applied at the boundaries of the structure. The SCEDs were modeled as nonlinear springs with an initial slackness of 12.7mm. Comparisons of analyses without SCEDs were made to determine how one-dimensional, axial ground motion and three-dimensional ground motion affect bridge response. Analysis were then run to determine the effectiveness of the SCEDs at restraining bridge motion during strong ground motion. The SCEDs were found to be effective at restraining the spans during strong three-dimensional ground motion. / Master of Science
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