UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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2004 - 200912010 - 20181

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    THE EFFECTS OF UNMITIGATED IDLE TIME ON THE PERFORMANCE OF MAGNETORHEOLOGICAL DAMPERS AS A STRUCTURAL PROTECTIVE SYSTEM.
    (2018) Khan, Sami Ur-Rahman; Phillips, Brian; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This thesis discusses the long-term performance degradation of seismic protective systems due to age and inactivity (termed “idle time effects”). Over the lifetime of a structures there is the potential for a significant reduction in ability for the structural control systems to mitigate earthquakes. This can affect the resilience of the structure and lead to uncertainty in engineering judgement when designing seismic protective systems. Further research into these idle time effects could help to create solutions to mitigate age-dependent performance loss. This paper will use magneto-rheological (MR) dampers, which serve as a good analog for other semi-active control devices, to study idle time effects on seismic protection. MR dampers provide controllable damping through the magnetization of small MR particles in a carrier fluid. These particles can settle over time, influencing their performance. Using a model MR fluid, accelerated testing was performed to analyze the consequences of idle time.
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    AN EVALUATION OF FLOOR RESPONSE SPECTRA FOR ACCELERATION-SENSITIVE NONSTRUCTURAL COMPONENTS SUPPORTED ON REGULAR FRAME STRUCTURES
    (2004-05-12) Kingston, Kevin M.; Medina, Ricardo A.; Civil Engineering
    This study evaluates the acceleration response of elastic nonstructural components (NSCs) subjected to earthquake-induced supporting structure motions. The objective is to provide insight into the development of the floor response spectrum (FRS) and its dependence on critical ground motion and structural system parameters such as the ground motion intensity, modal periods of the supporting structure, fundamental period of the NSC, strength of the structure, and location of the NSC with respect to the height of the supporting structure. The focus is on NSCs supported on regular moment-resisting frames. Results indicate that the FRS is highly dependent on the ratio of the period of the NSC to the modal periods of the supporting frame, the level of inelastic behavior of the frames and the location of the NSC. This study demonstrates that in several cases these effects are not adequately represented in floor design spectra recommended by current building codes.