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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2010 - 20182

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    CABLE RELIABILITY OF CABLE-STAYED BRIDGES
    (2018) Ganesh, Shashank; Fu, Chung C; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Redundancy is achieved by studying critical load paths and finding alternatives to implement them so that system’s function is not altered after the failure of one or several structural members. Reliability is considered during system operation and helps greatly in monitoring system’s health by applying techniques to the data collected and predicting failure of components of the system. James River Bridge, a harp-shaped cable-stayed bridge located 20 miles south-east of Richmond, Virginia is selected in this study. CSIBridge was used for developing a linear elastic model of the bridge to analyze the effect of a moving load during the event of a cable failure and time history response was recorded. ANSYS Mechanical APDL (ANSYS Parametric Design Language) which was further used to create a framework by developing a tool to integrate with MATLAB and calculate the probability of exceedance of the limit state of the cable.
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    Seismic assessment of curved bridges using modal pushover analysis
    (2010) Ahmed, Mohamed Salah; Fu, Chung C; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The assessment of existing bridge structures against earthquake threat has become a major issue lately, motivated by the maturity of seismic design of new structures, on one side, and by the recognition of the inadequate level of seismic protection, the aging and the constant need of maintenance of the existing ones, on the other. While nonlinear time history analysis (NL-THA) is the most rigorous procedure to compute seismic demands, many seismic-prone countries, such as United States, New Zealand, Japan and Italy, have recently released standards for the assessment of buildings, all of which include the use of the non-linear static analysis procedure (NSP), the so-called pushover. Recently Chopra and Goel (2002) proposed the modal pushover analysis (MPA) procedure that considers the effect of higher modes on the behavior of buildings. This research investigation is intended to evaluate the accuracy of the modal pushover analysis (MPA) procedure in estimating seismic demands for curved bridges after proposing some modifications that would render the MPA procedure applicable for bridges. For verification purpose, the nonlinear time history analysis (NL-THA) is also performed in order to quantify the accuracy of MPA. Three bridges were analyzed using both the MPA and NL-THA in addition to the standard pushover analysis (SPA). Maximum Demand displacements, total base shear and plastic rotations obtained from SPA and MPA are compared with the corresponding values resulting from the NL-THA. Comparison shows a good agreement between MPA and NL-THA results and MPA is deemed to be accurate enough for practical use. Furthermore, to evaluate the applicability of the MPA method for a wide range of bridges, a parametric study using both the MPA and NL-THA is performed. Results from the MPA for demand displacement and base shear are compared with results from the NL-THA. Also, the influence of different parameters on the behavior of curved bridges is studied. Parameters included the girder cross section (steel I vs. steel BOX), span length, number of spans, radius of curvature, and pier height. Pier height is found to have the most significant effect on bridge behavior as well as span length, while radius of curvature is found to have less influence on the behavior of curved bridges.