M.S. Theses

Permanent URI for this collection

https://digitalarchive.library.bogazici.edu.tr/handle/123456789/11707

Browse

Browsing M.S. Theses by Author "Ansal, Atilla."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Evaluating site effects for estimation of seismic ground response: a practical approach
    (Thesis (M.S.) - Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2013., 2013.) Çetiner, Barbaros.; Şafak, Erdal.; Ansal, Atilla.
    Expansion of scientific methodologies to estimate the probable extents of ground motion effects in earthquake-prone areas is crucial for proper planning, investigation, and design of engineering structures. In this regard, accurate estimation of site effects instigated by the terminal geological structure at a considered location, in the presence of a seismic tremor, plays a particularly significant role. The key emphasis of this document is to develop a practical ground response analysis procedure comprised of a line of objective, well-outlined and simple-but-adept individual processes to address this aspect of the problem. In this study, to achieve that goal, a total of 1188 ground response analyses were performed for a combination of ground motion selection/scaling and equivalent-linear site response analysis techniques – all of which by itself constitute the current agreed practice within their parts – at 10 accelerometer sites. Each location evaluated herein was selected so that the recording station is a part of the Turkish Strong Ground Motion Network, with readily accessible, detailed geotechnical and geophysical reports; and at least a single earthquake event record, that correspond to the 10 per cent exceedance level in 50 years, existing. This allowed for a direct comparison of the result patterns obtained using each analysis component with the actual earthquake response; thus a truthful appraisal of how changing different parts of the overall procedure is reflected in the attained approximation level. For each station, the main output of the proposed method is a uniform hazard spectrum (UHS), fashioned in a similar way as that in major seismic codes. Therefore, as an auxiliary outcome of this assessment, a case study presenting the insufficiency of the currently adopted site factors for faithful estimation of site effects, and a vital application regarding how the suggested approach may play a role in improving the existing seismic code practice is as well provided.
  • Thumbnail Image
    Item
    Microzonation with respect to rainfall - induced landslides
    (Thesis (M.S.)-Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2015., 2015.) İlhan, Okan.; Şafak, Erdal.; Ansal, Atilla.
    Expansion of scientific methodologies to quantify the rainfall – induced hazard paves the way for constructing proper investigation of potential landslide in interested areas. In this context, a simple, concise but sufficiently detailed to incorporate all the phenomena in itself microzonation methodology is proposed which merges two different approaches (1) Iverson (2000), which bears on the exact solution of Richards’ Equation and (2) uniform seepage condition, dependent on topographical features rather than solution to water movement equation in soil continuum. Such a straightforward concept enables utilizers to perform factor of safety calculations not exhaustive but elaborative on GIS system. In this study, hypothetical topography is at first produced to portray the efficacy of recommended algorithm with an intention that different soil conditions and fluctuations in rainfall intensities on soil mass are able to be evaluated. In addition to this, Tekirdağ City Center is selected to examine the pros and cons of proposed routine but all the required parameters for the analysis are specified by means of plenty of empirical correlations, which may lead to unexpected results. Thus, two additional methodology, Montgomery and Dietrich (1994), Mora and Vahrson (1994) are also, employed for the justification of below – stated method since the former one operates on similar parameters and the latter one sketches the potential hazardous locations in relevant area. The outcome of comparison between these three algorithms is able to be interpreted that suggested technique can fairly be presumed as one simulating the pore – pressure acumulations and corresponding factor of safety degradations properly.