Dissertations for Structural Engineering (Str.E)

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https://bspace.buid.ac.ae/handle/1234/923

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Browsing Dissertations for Structural Engineering (Str.E) by Author "Dr Gul Ahmed Jokhio"

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    Comparative Study of the Structural Behaviour of Cast Acrylic & Laminated Glass Under the Impact of Dynamic Loading in Aquatic Applications
    (The British University in Dubai (BUiD), 2023-12) ABUZOUR, MOHAMMED A. E.; Dr Gul Ahmed Jokhio
    Laminated glass (LG) and cast acrylic (CA) materials have differences in their structural behaviors regarding the impact of dynamic loading in aquatic applications. The difference can be due to these materials' consistency and mechanical properties. This study aimed to distinguish the differences in structural behaviors of cast acrylic and laminated glass in aquatic applications under the impact of dynamic loading and what industry guidelines and standards can be developed to ensure their safe and effective use in this setting. The study starts in Phase I by selecting the strip method for both LG and CA to observe the deflection magnitudes of hydrostatical pressure of a 40mm thickness tank wall that has a depth of 6m, and then a shell element model for both materials was built using CSI SAP software to establish accurate statistical modeling of the tank with same wall thickness and exerted hydrostatic pressure depth. The results in Phase I exhibited that CA sheets had 10% to 15% more deflection than it was in LG, and experienced negative bending moments of about 90 kN.m near the base edges, and around 40 kN.m as maximum positive bending moments. Whereas LG’s straining actions recorded a magnitude close to 100 kN.m as positive bending moments and almost 180 kN.m as negative bending moments near the edges at the same parameters of the study. In Phase II of the study, the materials were submitted to dynamic loads analysis to examine their structural boundaries. The model was established using LS Dyna software to mimic an accidental collision incident of amphibians and/or mammal creatures to the LG and CA tank walls. Masses, velocities, hydrostatic pressure, and wall thicknesses were all included in Phase II of the study to assess the impact of each variable on the built model. The study achieved accurate simulations since there were four different parameters in each analysis running cycle allowing sophisticated investigations of both materials by pushing their structural behavior under the impact loads of collisions to their extreme boundaries, especially when gradual incremental changes in the magnitude of each parameter are applied. The model was adjusted to compare the actual deflection and applied stress criteria with the aforementioned four variable parameters. The obtained results exposed the superiority of CA sheets in most of the collision cases in contrast with LG. CA sheets had the least deflection and stress values in regard to wall thickness, however, they showed a gradually increasing deflection against higher velocities in contrast with LG which revealed rather constant deflections versus the same set of velocity increments. LG sheets expressed a dramatic increase in the applied stress against the increment of the colliding mass, however, they could remain more conservative against recorded deflection magnitudes under the same increment set of moving mass. Finally, CA sheets recorded slightly lower deflection values than it was in LG under the increasing effect of hydrostatic pressure (collision depth) and eventually showed almost a constant behavior of stress but significantly lower than those recorded in LG sheets.
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    Modal Dynamics of Combined Offshore Wind Turbine and Monopile Foundation System: A Seismic Impact Assessment Study on System Dynamism
    (The British University in Dubai (BUiD), 2023-12) VENUGOPAL, HARIKUMAR; Dr Gul Ahmed Jokhio
    For the sustainability transition to evolve at a rapid pace, complex engineering systems are required to be reliable and effective in their operability. Even though offshore wind energy systems are a few decades old now, global adoption is not strong due to reliability issues, construction, operation, and maintenance complexities. The primary uncertainty in the structural engineering of this system lies in the dynamic behavior which is almost impossible to accurately compute. Seismic interactions at the seabed further complicate this. This dissertation conducts an in-depth modal dynamics analysis of an integrated offshore wind turbine and monopile foundation system, employing finite element analysis techniques. The study encompasses frequency domain analysis, eigenvalue extraction, and modal dynamic steps, incorporating seismic loads inspired by significant earthquake events, and the seismic impact on the system's dynamism is evaluated by evaluating system field and history outputs across system modal dynamics. Critical insights regarding the geometric variation effects on the dynamic traits of the combined system are retrieved by careful comparative evaluation.