Thesis Defense - Onur Cem Aygın (MSCE)

Onur Cem Aygın - M.Sc. Civil Engineering

Asst. Prof. Taner Yılmaz - Advisor 

Date: 26.08.2020

Time: 10:00

Location: This meeting will be held ONLINE. Please send an e-mail to gizem.bakir@ozyegin.edu.tr in order to participate in this defense.

TIME-DEPENDENT SEISMIC FRAGILITY ASSESSMENT OF AGING ORDINARY HIGHWAY BRIDGES SUBJECT TO FLOOD-INDUCED SCOUR

Thesis Committee:

Asst. Prof. Taner Yılmaz, Özyeğin University

Asst. Prof. Derya Deniz, Özyeğin University

Prof. Alp Caner, Middle East Technical University

Abstract:

Time-dependent seismic vulnerability of bridges is a topic that attracts significant research interest in recent years. This issue has begun to surface itself recently in the United States and Europe, where most of the concrete bridges are older than 70 years of age by today. Seismic performance of bridges may reduce in time due to several aging mechanisms such as chloride-induced corrosion in reinforced concrete members. Because of that, damage and loss estimations which are traditionally being conducted upon the pristine state of a structure may yield inaccurate results regarding future earthquake scenarios. Furthermore, performance of river-crossing bridges may be affected from scouring at pier foundations after a flood event due to the removal of soil around bridge piers. Unexpected increase in expected damage due to such mechanisms may lead to an increased risk for bridge infrastructure systems under the multi-hazard of earthquakes and floods. This study aims to present a stochastic framework to evaluate the time-dependent seismic fragility of highway bridges subject to flood-induced local scour.

In this thesis study, firstly, two different approaches for the development of seismic fragility curves are compared for their applicability and feasibility. Following that, possible aging mechanisms in an ordinary highway bridge are depicted and three-dimensional finite element models of the study bridge for different ages are generated incorporating various levels of scour to develop the time-dependent seismic fragility curves of bridges. Then, a ground motion data set representing the general seismicity of Turkey is assembled. For the combinations of all considered scour depths and bridge ages, nonlinear time-history analyses are performed to obtain the seismic demands. After a binary damage assessment, Method of Maximum Likelihood is employed to estimate the fragility parameters. Finally, seismic fragility surfaces are developed for different ages of the bridge. The outcomes of this study can be utilized in future efforts towards calculating the lifetime risk of ordinary highway bridges under the multi-hazard risk of earthquakes and floods.

Bio: 

Onur Cem Aygın was born on February 7th, 1995 on Tokat, Turkey, and raised there until his university years. He graduated from Tokat Teacher Training High School in 2013, and started his training for the Bachelor of Science degree in Civil Engineering on Ozyegin University, which he obtained in 2018. He continued his studies in Ozyegin University to obtain the Master of Science degree in Civil Engineering. His research is focused on the seismic vulnerability of ordinary highway bridges, incorporating the effects of structural deterioration and flood-induced scour. During his studies, he subsequently worked as a Teaching Assistant in the Civil Engineering Department of Ozyegin University.

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Kişisel Verilerin Korunması/Aydınlatma Metni

Özyeğin Üniversitesi Fen Bilimleri Enstitüsü bünyesindeki programlarda, izleyici olarak katılınan online platformlarda gerçekleştirilen aleni akademik faaliyetlerin sadece idari ve yasal yükümlülüklerin yerine getirilmesi amacıyla kayıt altına alındığı, söz konusu kayıt ile elde edilen kişisel verilerin ilgililer tarafından başka bir amaçla kullanılamayacağı hususunda şahsınızı aydınlatır, toplantıya gönüllü katılım ile bu hususu beyan ve taahhüt etmiş olduğunuzu belirtir, gereğini önemle rica ederiz. 

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