İnşaat Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.11779/1943

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Citation - WoS: 3
Citation - Scopus: 3
Assessment of the Disaster Recovery Progress Through Mathematical Modelling
(TMMOB İnşaat Mühendisleri Odası, 2020) Dikmen, Seyyit Ümit; Sönmez, Murat; Akbıyıklı, Rıfat
Natural disasters, especially major earthquakes, cause widespread devastation in the built environment. Hence, the major component of the recovery in its aftermath constitutes a chain of projects starting at different times, having different costs and durations. In this study, the post disaster recovery curve modelled through a mathematical approach taking into account these properties of the projects. The approach followed is based on the project S-curve concept that provides the opportunity to simulate the progress by outlining the project spending. Well-known mathematical functions are adapted to model the project spending and the handover processes. Monte Carlo simulation is performed to evaluate the general behavior of the recovery curve using the model developed. Weibull distribution is used to generate the model’s parameters. Results of the Monte Carlo simulation demonstrate that the recovery process exhibits an S-shape, the duration of initial portion and the slope of the bulk portion being significantly governed by the level of preparedness of the community.
Bitişik Yapıların Deprem Performanslarının Ayrı veya Bitişik Olarak Kırılganlık Eğrileri Yardımı ile İncelenmesi
(2015) Akbulut, Ali; Boduroğlu, M. Hasan
Mevcut yapıların deprem performans, risk ve güçlendirme analizlerinde, yanındaki yapı ile olan ilişkisini uygun modelleme teknikleri ile analiz aşamasının içine dâhil ederek, sonuçların tekbaşına analiz edilmiş binalara göre olan farklılıklarını incelemek önemli bir konu olarak ortaya çıkmaktadır. Bu çalışmada, literatürdeki komşu binaların birbirleri ile olan etkileşim modelleri, statik itme analizi ve doğrusal olmayan hesap yöntemleri, deprem ivme kayıtlarının bir veri tabanından alınması ve tasarım spektrumuna göre ölçeklenmesi, zaman tanım alanına göre hesap yöntemi, hareket denkleminin Newmark-b yöntemi ile sayısal çözümü ve kırılganlık eğrileri ile bina performans seviyelerinin belirlenmesi konuları incelenmiştir. Bitişik (komşu) ve birbirine benzer binaların, deprem performanslarının birbirileri ile olan etkileşimli ve deprem yönüne göre değişen bir şekilde yapı blokları olarak ele alınıp, hasar görebilirlik-kırılganlık eğrileri yönünden değerlendirilmeleri incelenmiş ve binaların ayrı ayrı analiz edildikleri duruma göre daha farklı sonuçlar verdiği tespit edilmiştir.
Citation - WoS: 6
Citation - Scopus: 6
Case Study on Seismic Behavior of Aseismically Designed Reinforced Concrete Frame Structures
(2018) Oyguc, Evrim; Oyguc, Resat; Tönük, Gökçe
In this study, the seismic performances of two aseismically designed plan-irregular reinforced concrete frame (RCF) households damaged during the October 23, 2011 Van earthquake are assessed. Since no strong ground motion recordings from the main shock were available, first, strong ground motion parameters of the event are evaluated and then compatible with these parameters suits of real records are selected and scaled to match with the event's simulated acceleration spectrum to be used in the analytical investigations. The results of previous reconnaissance studies, in which one of the present authors was involved, are then discussed. Capacities of the considered RCF's are determined applying a 3D single-run adaptive pushover procedure that is capable of considering the effect of plan irregularities. The performance assessment procedure based on the current 2007 Turkish Earthquake Code is then applied to these investigated buildings. Additionally, nonlinear dynamic time history analyses are carried out using the previously selected time histories. The hysteretic behavior of the considered buildings is examined as the consequence of the conducted analyses and considering the different suits of selected ground motions, the seismic response of the buildings is evaluated in terms of interstorey drifts. None of the buildings are found to satisfy the expected performance level. Moreover, the numerical results are found to have good correlation with the field observation results.
Contribution of Gravity Frames To Seismic Performance of Steel Moment Resisting Frames
(2018) Zorlu, Mustafa; Şeker, Onur; Akbaş, Bülent; Shen, Jay
Traditionally, lateral stiffness and strength of the gravity frames in steel buildings are neglected in structural analysis. During the past earthquakes, such as Northridge, USA, 1994 and Kobe, Japan, 1995, unexpected failures were detected at beam-to-column connections of steel moment resisting frames (MRFs). In the aftermath of these earthquakes, extensive research has been carried out to reveal the causes of these failures. Based on the detailed observations, it is likely that the reserve capacity provided by the gravity frames prevented the highly damaged steel buildings from collapsing, since majority of the moment-resisting connections failed prematurely during the Northridge earthquake (1994). Even though the influence of gravity frames (GFs) on structural behavior can be substantial, little attention is paid to evaluate its impact on structural response. With this paper, the contribution of interior GFs in seismic performance of special moment resisting steel frames (SMRFs) is evaluated. For this purpose, 4- and 9-story SMRFs were designed in accordance with the requirements of Draft Turkish Seismic Code (2016). The frames are, then, subjected to incremental dynamic analysis. To evaluate the contribution of the interior GFs on the overall seismic performance of structural system, inelastic behavior of shear tab (simple) connections at beam-to-gravity-only columns were idealized as semi-rigid joints. A general purpose structural analysis software, ETABS, is utilized for the analyses. The results of the study are presented in terms of story drifts, base shear vs. roof displacement.
Citation - WoS: 36
Citation - Scopus: 48
Cyclic and Monotonic Compression Behavior of Cfrp-Jacketed Damaged Noncircular Concrete Prisms
(2016) İlki, Alper; Dalgıç, Korhan Deniz; İspir, Medine
This paper focuses on rehabilitation/strengthening of damaged concrete prisms through external carbon-fiber-reinforced polymer (CFRP) jacketing. In order to evaluate the efficiency of the strengthening method on the damaged concrete prisms, an experimental study including 22 concrete prisms with square and rectangular cross sections was carried out. The parameters of the experimental study are the damage levels. Furthermore, effects of loading scheme (monotonic or cyclic) and cross section type (square and rectangular) were investigated in the existence of damage. The concrete prisms were tested under compression stresses up to three specified axial deformation levels to be representative of slight, moderate, and severe compression damages before strengthening. Tests were repeated after rehabilitation/strengthening of damaged specimens with CFRP jacketing. Test results showed that CFRP rehabilitation/strengthening was effective on enhancement of strength and deformability of the damaged concrete prisms. However, the efficiency of the strengthening method in terms of compressive strength tended to reduce when the level of damage increased. Furthermore, an available model is modified to include the effects of damage level, and the modified model is shown to produce accurate results. (C) 2015 American Society of Civil Engineers.
Citation - WoS: 10
Citation - Scopus: 11
Damage Accumulation Modelling of Two Reinforced Concrete Buildings Under Seismic Sequences
(Springer, 2023) Tönük, Gökçe; Oyguç, Reşat; Oyguç, Evrim; Uçak, Doruk
The extent of earthquake damage depends solely on the seismicity, site conditions and vulnerability of the building stock in a region. Hence, studies to assess the seismic behavior of building stocks with similar vulnerabilities are important to mitigate seismic risk in earthquake-prone regions. This study aims to simulate the seismic behavior of selected reinforced concrete (RC) school buildings by modelling damage accumulation under multiple earthquakes sequence. The observed data of two RC school buildings heavily damaged after the 2011 Van earthquake sequence in Turkey, namely, the Gedikbulak and Alakoy schools is used. Among these two school buildings, the Gedikbulak school building collapsed immediately after the main excitation, while the Alakoy school building withstood several seismic sequences, suffering heavy damages. In this study, three-dimensional numerical models that can consider the deterioration effects are developed and the capacities of the buildings were evaluated by conducting a force-based adaptive pushover procedure. Additionally, non-linear dynamic analyses were conducted using the concrete plastic damage model. Both degrading and conventional material models were used to examine the structural response under multiple ground motion sequences. The hysteretic behaviors of the studied buildings are presented. Consequently, analytical results are well correlated with the reconnaissance studies and neither of the considered structures are found to satisfy the design performance level.
Deprem Yalıtımlı ve Geleneksel Binalarda Tesisatlar İçin Sismik Koruma Hesabı ve Gereksinimi
(2023) Şadan, Bahadır
İnşaat mühendisleri, olası büyük bir deprem senaryosu için, binanın taşıyıcı elemanlarını ve içinde yaşayan insanların can güvenliğini sağlamak için tasarım yapmaktadırlar. Halbu - ki, büyük bir deprem sonrası mali kayıp tabloları incelendiğinde, mali kayıpların en büyük bölümünü yapısal olmayan elemanlardaki hasarın oluşturduğunu görebiliriz. Dışarıdan bakıldığında hasarsız gözüken, taşıyıcı elemanlarında hasar olmayan bir binanın içerisine girildiğinde, sadece kendi ağırlığını taşımak için askılanmış ve doğru sismik koruma uygulan- mamış tesisatların, tavaların ve diğer tavana asılı ekipmanların, yüksek deprem ivmesi nedeni ile hasar gördüğü ve binanın kullanılamaz hale geldiği gözlemlenebilir. Bu durum özellikle deprem sonrası hemen hizmet vermesi gereken kritik binalar için (ör. hastaneler, ulaşım ve haberleşme yapıları vb.) daha büyük önem taşımaktadır. Sağlık Bakanlığı bu bağlamda, 2013 yılında yayınladığı bir genelge ile, 1. ve 2. derece deprem bölgesindeki, 100 ve üzeri yatak kapasiteli tüm devlet hastanelerinde sismik izolatörler ile deprem yalıtımını zorunlu hale getirmiştir. Deprem yalıtımı, binaya etkiyen deprem ivmelerini dolayısı ile deprem kuvvetlerini çok büyük oranda sönümleyerek, sadece bina taşıyıcı siste- minin değil aynı zamanda diğer muhteviyatın (tesisatlar, ivmeye hassas cihazlar vb.) deprem sırasında korunmasını sağlamaktadır. Fakat bu azaltma deprem etkilerini tamamen yok et- mediği için tesisatlarda sismik koruma yapılmasına gerek olmadığı anlamına gelmemektedir. Bu bildiride, 18 Mart 2018, 30364 sayılı Resmi Gazete’de yayınlanarak, 1 Ocak 2019 tarihi itibari ile resmi olarak yürürlüğe giren Türkiye Bina Deprem Yönetmeliği’ne (TBDY) göre elektrik ve mekanik tesisatların sismik koruma hesabı tariflenmektedir. Ayrıca yine TBDY’e göre deprem yalıtımlı binalarda sismik koruma hesabı gereksinimi irdelenmektedir.
Citation - WoS: 9
Citation - Scopus: 10
Determination of Building Age for Istanbul Buildings To Be Used for the Earthquake Damage Analysis According To Structural Codes by Using Aerial and Satellite Images in Gis
(Springer Verlag, 2017) Konukcu, Betül Ergün; Karaman, Himmet; Şahin, Muhammed
Istanbul is located in one of the most active seismic zones in the world. Since Istanbul is the industrial, commercial, cultural and educational center of Turkey, it attracts ongoing migration from all over Turkey. However, those migrations caused unplanned construction and those unplanned constructions led to the formation of vulnerable and undocumented building stock in Istanbul. Many scientific studies estimated that Istanbul is expecting a major earthquake and the expected damage to the structures will be extensive. Therefore, there have been a lot of building damage estimations for the possible Istanbul earthquake to recommended precautions and to be prepared. A major disadvantage of Istanbul case is the lack of knowledge for the absolute number of buildings and the ages of those buildings. Up to now, many studies for Istanbul used the building dataset of Istanbul with the number starting from 1.1 to 1.5 million without the absolute age information. To make a correct or reliable earthquake damage estimation, a building database that contains at least building age, construction type and number of floors is required in most of the earthquake loss assessment software. This paper aims to determine the buildings of Istanbul and the age of them, according to structural codes for the earthquake zones by using aerial and satellite images of Istanbul. The classification should be based on the regulation so as to minimize the age classes and maximize the accuracy. First building regulations in Turkey came into force in 1940 in order to determine essential conditions for the realization of functional, safe and disaster-resistant building design in Turkey. Last updated building code regulations have come into force in 2007 in Turkey. It was also important to investigate the proper building detection method for the aim of this study, and it was determined as the manual digitization. In this study, the buildings of Istanbul and the age of them are determined for every single building, by digitizing the selected aerial and satellite images of Istanbul based on the official structural codes in Turkey. Thus, first the exact number and location of buildings in Istanbul and every single buildings age were determined. The results were also validated with two separate studies of Istanbul for different periods of times. By this way, earthquake damage analysis for the Istanbul buildings can be run for the real building data of Istanbul with any earthquake loss assessment software.
Citation - WoS: 54
Citation - Scopus: 56
Experimental Evaluation of Eaf Ladle Steel Slag as a Geo-Fill Material: Mineralogical, Physical & Mechanical Properties
(2017) Yıldırım, İrem Zeynep; Prezzi, Monica
Despite of significant efforts in the last decades towards utilization of steel slag in the construction industry, steel slag stockpiling and landfilling operations do not seem to be declining in steel-producing countries. Use of steel slag as a construction material requires understanding of its engineering properties and development of a methodology to address its swelling potential. This paper focuses on the results of a series of laboratory tests (grain-size analysis, X-ray diffraction, specific gravity, compaction, maximum and minimum dry unit weight, direct shear, and long-term swelling tests) performed on samples of electric-arc-furnace ladle (EAF(L)) steel slag to assess its potential to be used as a geo-material. Direct shear test results indicated that the EAF(L) steel slag exhibits comparable frictional properties to angular crushed sand. Based on the leachate concentration levels from TCLP analyses, the EAF(L) steel slag tested was classified as Type III Solid Waste. The long-term, one-dimensional (1D) swelling test results showed continued volumetric expansion even after more than 16 months of monitoring. Replacing 5-10% by weight of EAF (L) steel slag with Class C fly ash reduced the 1D swelling to negligible levels. (C) 2017 Elsevier Ltd. All rights reserved.
Citation - WoS: 5
Citation - Scopus: 7
Factors Affecting Site-Specific Response Analysis
(Taylor and Francis, 2022) Tönük, Gökçe; Ansal, Atilla M.
The engineering purpose of a site-specific response analysis is to estimate the uniform hazard acceleration spectrum on the ground surface for a selected hazard level. One of the mandatory components for site response analyses is one or more representative acceleration time histories that need to be scaled with respect to the calculated seismic hazard level for the selected site. The selection and scaling procedures of earthquake acceleration records play an important role in this approach. The effects and differences in using two different scaling approaches are studied: scaling with respect to ground motion parameters and response spectrum scaling. A set of homogeneous ground motion prediction relationships are developed for peak ground acceleration, peak ground velocity, root-mean-square acceleration, Arias intensity, cumulative absolute velocity, maximum spectral acceleration, response spectrum intensity, and acceleration spectrum intensity based on a uniform set of acceleration records for ground motion parameter scaling.The uncertainties associated with site response analysis are considered as epistemic and aleatory uncertainties in source characteristics, soil profile, and soil properties. Aleatory variability is due to the intrinsic randomness of natural systems; it cannot be reduced with additional data (Passeri et al. 2020), however; its variability may be modeled by probability distribution functions. Thus, one possibility is to determine the probability distribution of the acceleration spectrum calculated on the ground surface for all possible input acceleration records, site profiles, and dynamic soil properties. The variability in the earthquake source and path effects are considered using a large number of acceleration records compatible with the site-dependent earthquake hazard in terms of fault mechanism, magnitude, and distance range recorded on stiff site conditions. Likewise, a large number of soil profiles may be considered to account for the site condition variability. The uncertainties related to dynamic soil properties may be considered as possible variability of maximum dynamic shear modulus in site response analyses. A methodology is proposed to estimate a uniform hazard acceleration spectrum on the ground surface based on the probabilistic assessment of the factors involved in site response analysis. The uniform hazard acceleration spectra obtained from a case study are compared with the spectra calculated by probabilistic models proposed in the literature.
Citation - WoS: 5
Citation - Scopus: 5
Gis-Based Assessment of Seismic Vulnerability Information of Old Masonry Buildings Using a Mobile Data Validation System
(American Society of Civil Engineers (ASCE), 2021) Özsoy Özbay, Ayşe Elif; Ünen, Hüseyin Can; Karapınar, Işıl Sanrı
This study proposes a geographic information system (GIS)–based rapid visual screening approach for seismic vulnerability assessment of masonry buildings in culturally and architecturally important historical regions. Through the application of the proposed methodology, a prioritization strategy for seismic vulnerability assessment of the heritage masonry buildings in Galata, a historical center of Istanbul, Turkey, was performed. This approach is based on an integrated methodology including a data collection process conducted through visual inspections and standard survey forms filled on site, generation of a georeferenced building database enabling the calculations and mapping of the vulnerability scores, and camera-based data validation process. The validation process provides an online collaborative mobile mapping system through georeferenced images gathered from the field. By the updatable data validation process, the reliability and efficiency of the GIS-based building database are enhanced by minimizing the errors during the visual screening and the cost of data correction due to reinspection is reduced.
Lessons From the Rector of the First Fully Flipped Learning University
(FLR The Flipped Learning 3.0 Magazine, 2018) Şahin, Muhammed
Sahin: MEF Educational Institutions was founded in the 1970s by İbrahim Arıkan, an educator and businessman. In 1996, he founded MEF national and international K-12 schools in Istanbul and Izmir. In 2013, he founded MEF University. As both educator and entrepreneur, Arıkan was in a unique position to establish a university. He was aware the educational system was not well suited to the current needs of students and society and envisioned a totally new educational approach for MEF University. To find this approach, he brought me on board as founding rector. Having been rector of Istanbul Technical University from 2008 to 2012, I had a strong background in innovations in education. During our first meeting, Arıkan made it clear that if he was going to establish a university, it needed to be unique and take a different mentality to the educational needs of today’s students. I vividly remember Ibrahim emphatically declaring that if he could not make a change to higher education, he would call a halt to his aspirations for opening a university.
Citation - WoS: 4
Citation - Scopus: 6
Modal Identification of the First Bosporus Bridge During Hanger Replacement
(Taylor & Francis, 2020) Dikmen, Seyyit Ümit; Aytulun, Emre; Luş, Hilmi; Safak, Erdal; Soyöz, Serdar; Apaydın, Nurdan
As the oldest of the three suspension bridges spanning the Bosporus, the (First) Bosporus Bridge wascommissioned in 1973. Its main span of 1074 m was originally designed to be suspended by inclinedhangers; in 2015, the original inclined hangers were replaced by vertical ones. In-situ ambient vibra-tion measurements were taken at different stages of this operation to gain an understanding of theeffects of the hanger cable orientation on the overall dynamic behaviour of the bridge. Measurementswere also recorded for various periods spanning several weeks to observe operational variations onthe modal frequencies of vibration. Measurements were made on the tower, the deck and the hang-ers. It was observed that, as a result of the hanger replacement, frequencies of the modes involvingpredominant deck motion decreased on the order of 6 to 16% while the frequencies of the modesinvolving predominant tower motion showed almost no change. A finite element model of the Bridgewas also developed to further investigate the physical reasons behind the observed changes in modalfrequencies and similar trends were observed in the modal frequencies yielded by the finite elementmodels developed for the inclined and the vertical hanger configurations.
Citation - WoS: 10
Citation - Scopus: 16
Out-Of Seismic Performance of Bed-Joint Reinforced Autoclaved Aerated Concrete (aac) Infill Walls Damaged Under Cyclic In-Plane Displacement Reversals
(Elsevier Sci Ltd, 2023) İlki, Alper; Demir, Uğur; Halıcı, Ömer Faruk; Zabbar, Yassin
The infill walls made of Autoclaved Aerated Concrete (AAC), which is a lightweight, fire resistant and energy efficient material, provide effective insulation solutions for building types of structures and becoming more and more popular in earthquake prone regions. Although the number of experimental tests examining the seismic response of clay brick infills is extensive, the amount of prior research on infill walls built of AAC blocks is rather limited. Past research revealed that the use of bed-joint reinforcement is one of the promising solutions to improve the global seismic response of masonry walls by enhancing strength and displacement capacity. In this study, the out-of-plane (OOP) seismic performance of AAC infill walls with flat-truss and innovative cord-type bed-joint reinforcement is experimentally evaluated. Also, consideration is given to the prior in-plane (IP) damage, which was found to degrade the seismic performance of infills in OOP direction. For this purpose, three IP and four OOP, in total, seven experimental tests were performed on four full-scale AAC infill wall specimens. The test parameters were selected in such a way as to make it possible to parametrically compare the OOP performance of AAC infills with flat-truss and cord-type bed-joint reinforcements with unreinforced AAC infill walls, together with the effect of prior IP damage on the OOP response of unreinforced AAC infill walls. It was found that the use of innovative cord-type bed-joint reinforcement improved the OOP strength to a similar extent to what was obtained from the truss-type reinforced specimen. In terms of ultimate displacement and energy dissipation capacity enhancement, the specimen with cord-type reinforcement performed better. In addition, the damages formed due to IP cyclic displacement reversals up to 0.005 drift ratio, which is defined as the drift limit for buildings with brittle infill walls in certain design codes, resulted in a significant reduction in the OOP strength and stiffness properties of AAC infills. The theoretical OOP strength calculations were found to provide unconservative strength values for the IP-damaged specimens.
Citation - WoS: 28
Citation - Scopus: 41
Performance of High-Damping Rubber Bearings for Seismic Isolation of Residential Buildings in Turkey
(Elsevier, 2021) Murota, N.; Tuzun, C.; Mori, T.; Şadan, Bahadır; Wakishima, K.; Suzuki, S.; Sutcu, F.; Erdik, M.
The applicability of high-damping rubber bearings for seismic isolation of residential buildings in Turkey is studied using numerical and experimental approaches. Seismic isolation system composed of high-damping rubber bearings is designed according to the recently updated Turkish Building Seismic Code-2018 (TBSC2018). Three model buildings of different height at assumed seismically active area are chosen from an actual building database, on which, equivalent lateral force procedure, and time history analyses are carried out. The seismic responses of the buildings are evaluated and the seismic isolation system's efficiency is confirmed. It is pointed out that the requirements in the new code in terms of the maximum allowable shear strain of elastomeric isolators are excessively conservative for those isolators with much larger capacity which is verified by sufficient test data, and as a result, designed isolator size becomes larger than necessary from a practical aspect. In order to verify the isolator design without compliance of shear strain limitation in the code, full-scale prototypes of high-damping rubber bearings are specially designed, developed and are subjected to dynamic loading test under test protocol specified in the code. The specific values of test conditions, such as compressive force, shear displacement and frequency, are developed referring several projects in Turkey. The results are comprehensively discussed and the applicability of high-damping rubber bearing for seismic isolation of residential buildings in Turkey is concluded with numerical and experimental approaches and a possible modification of TBSC2018 regarding maximum shear strain is proposed.
Citation - WoS: 1
Citation - Scopus: 1
Probabilistic Seismic Microzonation for Ground Shaking Intensity, a Case Study in Türkiye
(Springer, 2023) Tönük, Gökçe; Ansal, Atilla
The purpose of seismic microzonation is to estimate earthquake characteristics on the ground surface based on a probabilistic approach to mitigate earthquake damage in the foreseeable future for the new buildings, as well as for the existing building stock. The probabilistic analysis and related results are very important from an engineering perspective since the nature of the problem can only be dealt with in a probabilistic manner. The uncertainties associated with these analyses may be large due to the uncertainties in source characteristics, soil profile, soil properties, and building inventory. At this stage, the probability distribution of the related earthquake parameters on the ground surface may be determined based on hazard-compatible input acceleration-time histories, site profiles, and dynamic soil properties. One option, the variability in earthquake source and path effects may be considered using a large number of acceleration records compatible with the site-dependent earthquake hazard. Likewise, large numbers of soil profiles may be used to account for the site-condition variability. The seismic microzonation methodology is proposed based on the probabilistic assessment of these factors involved in site response analysis. The second important issue in seismic microzonation procedure is the selection of microzonation parameters. The purpose being mitigation of structural damage, it is possible to adopt earthquake parameters like cumulative average velocity (CAV) or Housner intensity (HI) that was observed to have better correlation with building damage after earthquakes. A seismic microzonation procedure will be developed with respect to ground shaking intensity considering probabilistic values of the cumulative average velocity (CAV) or Housner intensity (HI).
Citation - WoS: 3
Citation - Scopus: 2
Reconnaissance and Discussion on Ground Motion Induced by the 2023 Türkiye-Syria Earthquake
(Taylor and Francis Ltd., 2025) Towhata, I.; Çağlayan, P.Ö.; Tönük, G.; Erginağ, U.C.; Sendir Torisu, S.
This paper discusses the output from the damage reconnaissance conducted after the 2023 Türkiye-Syria earthquake. First, a large landslide occurred in a limestone gentle slope without much ground water. Second, the ground subsidence in the coastal area does not comply the the local soil conditions and other observed post-seismic situations. Third, the acceleration records exhibit stronger motion with longer period and shorter duration towards the western end of the causative fault and suggest supershear rupture. To understand these features of the ground motion, this paper proposes a hypothetical model that can reproduce these observations to a good extent. © 2025 Taylor & Francis Group, LLC.
Citation - WoS: 17
Citation - Scopus: 19
Seismic Assessment of Ductile Concentrically Braced Frames With Hss Bracings
(Elsevier, 2019) Akbaş, Bülent; Şeker, Onur; Faytarouni, Mahmoud; Shena, Jay
A study on the seismic ductility demands on square HSS braces in special concentrically braced frames (SCBFs) is presented to address the seismic risk of braces in existing SCBF buildings designed according to both previous and current AISC Seismic Provisions. First, the paper discusses the development of ductility-based fragility curves by employing specimens with various width-to-thickness and slenderness ratios collected from 16 experimental programs from 1978 to today. Second, the constructed fragility curves are used to estimate the vulnerability of square HSS braces to the damage state of fracture using the brace ductility demand as engineering demand parameter. Then, the seismic risk of braces in terms of fatigue life is evaluated under 30 earthquake ground motions using a seven-story office building designed following requirements of previous and current design practice. The study concludes that braces in SCBF designed in compliance with the previous and current AISC Seismic Provisions are subject to a high probability of fracture under earthquake ground motions characterized by different intensity levels, which in turn might lead to underestimation of the overall seismic risk.
Seismic Behavior and Design of Reinforced Autoclaved Aerated Concrete Load-Bearing Panel Walls
(Taylor & Francis Ltd, 2026) Ugurlu, Koray; Halici, Omer Faruk; Demir, Cem; Comert, Mustafa; Ilki, Alper
Since the 1970s, numerous low-rise buildings in T & uuml;rkiye constructed with AAC load-bearing panels have withstood devastating earthquakes without significant damage, demonstrating a lightweight yet robust solution for seismic regions. This study investigates the seismic performance of AAC load-bearing panel wall systems through material tests, member-level cyclic in-plane testing, and finite element micro-modeling. The experimental results showed that individual panel behavior initiated at low lateral drift ratios of 0.25-0.50%, accompanied by measurable uplift and rocking at panel bases, with flexure governing failure in two-panel walls and combined flexure and diagonal tension - shear governing failure in four- and six-panel walls. Numerical models exhibited adequate reliability in terms of strength, stiffness, and cumulative energy, when validated against experimental data. The load-bearing capacity in the numerical simulations increased with both the number of panels and higher axial loads, consistent with observed experimental trends. These combined findings were used to determine seismic design factors leading to recommended values of D = 2 for overstrength and R = 4 for structural behavior. Experimental results were compared with corresponding design documents, including ACI 523.4 R and the Turkish Building Earthquake Code (TBEC). The findings indicated that flexure predominantly governed the failure of two-panel walls, while combined flexure and diagonal tension - shear mechanisms governed the failure of four- and six-panel walls. Accordingly, a revised diagonal tension capacity expression is proposed for the seismic design of AAC systems in future versions of TBEC.
Citation - WoS: 8
Citation - Scopus: 8
Site Response Analysis in Performance Based Approach
(Elsevier Sci Ltd, 2024) Ansal, Atilla; Tönük, Gökçe; Sadeghzadeh, Shima
A performance based approach for site response analysis requires a probabilistic approach accounting for the observed variability in soil stratification and engineering properties of the soil layers. The major variability in site-specific response analysis arises from the uncertainties induced by the (a) local seismic hazard assessment, (b) selection and scaling of the hazard compatible input earthquake time histories, (c) soil stratification and engineering properties of encountered soil and rock layers, and (d) method of site response analysis. Even though the uncertainties related to first item, local seismic hazard assessment, has primary importance on the outcome of the site-specific response analyses, the discussion in this article focuses on the possible uncertainties in selection and scaling of the hazard compatible input earthquake time histories, soil stratification, thickness, type and their engineering properties, depth of ground water table and bedrock and properties of the engineering bedrock. One alternative may be to conduct site response analyses for large number of soil profiles generated by Monte Carlo simulations using relatively large number of hazard compatible acceleration time histories to assess probabilistic performance based design acceleration spectra and acceleration time histories calculated on the ground surface with respect to different performance levels. A remaining issue may be considered as the variability induced by 1D, 2D, and 3D site response analysis.

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