Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026Scopus SJRQ1/r/munzur/1119
  Failure of a Code-Compliant Reinforced Concrete Building: Damage Patterns and Nonlinear Seismic Response

  Onat, Onur; Karaşin, İbrahim Baran; Yön, Burak; Varolgüneş, Sadık; Öncü, Mehmet Emin; Uslu, Ali

  This study investigates the seismic performance limitations of a newly constructed reinforced concrete building that collapsed during the 6 February 2023 Kahramanmaraş–Elbistan earthquake despite formal compliance with current seismic design requirements. Beyond the specific earthquake event, the study addresses a broader scientific problem: the limited understanding of the relationship between observed damage mechanisms and nonlinear dynamic response in mid-rise reinforced concrete buildings. The first part classifies recurring structural and non-structural damage patterns identified in newly constructed RC residences. The second part presents a nonlinear fiber-based static and dynamic analysis of a collapsed mid-rise building. Nonlinear dynamic analyses were conducted using ground motion records scaled to match the site-specific elastic design spectrum defined by TBDY 2018, corresponding to predefined seismic performance levels rather than an incremental dynamic analysis framework. The results indicate that an extremely low shear wall–to–floor area ratio (0.0357%) combined with asymmetric vertical element distribution significantly amplified torsional response and local shear demands. Nonlinear dynamic analyses showed that critical shear walls exceeded Collapse Prevention limits under DD2-level excitation, while system-level shear contribution limits remained within code-defined thresholds. Dynamic base shear demand corresponded to approximately 30% of the maximum nonlinear capacity obtained from pushover analysis, indicating that localized member failure rather than global strength deficiency governed the collapse mechanism. The analytically identified critical members were consistent with the observed collapse configuration, particularly at the soft ground story. The findings demonstrate that prescriptive code compliance alone may not ensure satisfactory seismic performance when structural irregularities, torsional amplification, and detailing deficiencies coexist. The results are consistent with damage patterns reported in other recent destructive earthquakes and contribute to improving the understanding of collapse mechanisms in code-compliant RC buildings.

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  AtıfScopus4·OpenAlex7

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• MakaleAçık Erişim2024Scopus SJRQ2/r/munzur/2139
  Seismic Resistance and Performance Evaluation of Masonry Dwellings After the February 6, 2023, Kahramanmaraş Earthquake Sequence in Türkiye

  Onat, Onur; Yön, Burak; Uslu, Ali; Öncü, Mehmet Emin; Varolgüneş, Sadlk; Karaşin, I.B.; Gör, Mesut

  On February 6, 2023, two catastrophic earthquakes occurred on the East Anatolian Fault. The earthquakes had magnitudes of Mw = 7.7 and 7.6 and struck Kahramanmaraş-Pazarclk and Kahramanmaraş-Elbistan, respectively. The Kahramanmaraş-Pazarclk earthquake was triggered at 04:17 local time on the Dead Sea Fault (a branch of the East Anatolian Fault). The last earthquake on the addressed fault occurred about 500 years ago. The recorded peak ground acceleration (PGA) at the Pazarclk station reached 2.05g. In addition, the Pazarclk earthquake triggered two independent earthquakes, the Nurdaǧl and Islahiye earthquakes, which occurred 10 min later than the Pazarclk earthquake. However, the last earthquake, with its epicenter in Kahramanmaraş-Elbistan, struck at 13:24 local time. The recorded PGA for the Elbistan earthquake is 0.68g. This study aims to present the fault rupture mechanism of the February 6, 2023, Kahramanmaraş earthquakes, earthquake characteristics, and to evaluate the performance of masonry dwellings during the Kahramanmaraş earthquake doublet, which affected 10 provinces and numerous towns and villages. This paper also aims to illustrate the damage and failure mechanisms of the masonry dwellings, despite unexpectedly high accelerations that exceeded the design spectrum in the field, specifically in Kahramanmaraş, Gaziantep, Hatay, and Malatya, according to the current earthquake code in use.

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  AtıfScopus16·OpenAlex22

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• MakaleYalnız künye2023Scopus SJRQ2/r/munzur/1825
  An Estimation Proposal for Engineering Properties of Modified Concrete by using Standalone and Hybrid GRELM

  Cemalgil, Selim; Onat, Onur; Aruntaş, Hüseyin Yılmaz

  The presented study pertains to an attempt to propose a novel prediction model to predict the flexural and compressive strengths of concrete modulated using steel fiber (SFb) and silica fume (SF). A completed experimental investigation is adopted for the current study, and a research plan is employed. Three different superplasticizers amount (SP), different SF replacement ratios, and a constant amount of SFb were used by the weight of cement to meet the C25 target strength. A sum of 16 distinct mixtures designed by changing SP and SF ratios were developed. Furthermore, SFb was added at a fixed rate of 65 kg/m3 to all planned concrete mixes. In addition, SFb was used to create a 16-mix design. Finally, a total of 32 distinct mix designs were created. Produced, hardened specimens were exposed to two different curing conditions. This research uses the mechanical characteristics of concrete treated with SF, SP, and SFb to estimate by conducting standalone and hybridized generalized extreme learning machine (GRELM) algorithms based on available experimental data in terms of the metaheuristic aspects of this work. With continuous input data, four separate data sets were constructed. Compressive strength and flexural strength were estimated separately. With the aid of the Grey Wolf Optimization (GWO) and Particle Swarm Optimization (PSO) algorithms, binary and ternary hybrid approaches were developed and tested on the data. Four distinct estimation models were suggested. Two quality metrics were used to evaluate the estimation performance: Root Mean Square Error (RMSE) and correlation of determination (R2). The estimation results showed that the hybridized GRELM-PSO-GWO estimation model that was built for prediction was relatively successful in all sets.

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  AtıfScopus4·WoS3·OpenAlex2

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• MakaleYalnız künye2022Scopus SJRQ1/r/munzur/3039
  A novel prediction model for durability properties of concrete modified with steel fiber and Silica Fume by using Hybridized GRELM

  Cemalgil, Selim; Gül, Enes; Onat, Onur; Yılmaz Aruntaş, Hüseyin

  The service life performance of conventional and modified concrete subjected to harsh climatic condition environment is directly related to durability properties of concrete like abrasion, freezing and thawing cycles. These properties are critical issues that should be predicted before performing experimental test. On this basis, the basic purpose of this paper is to predict the abrasion loss, freezing and thawing properties of concrete modified with silica fume (SF) and steel fiber (SFb) by using mix design and additional properties. From this point of view, a conducted experimental study was selected as a case study. In the control concrete (CC) mixtures, Portland cement, crushed stone aggregate, and superplasticizer (SP) were used in the selected experimental study. SP in concrete mixtures was used in the amounts of 1.0%, 1.5%, and 2.0% by weight of cement, and so modified concrete was produced with and without SFb according to the target strength of C25. Furthermore, SF and SFb were used in different amounts to modify the concrete. The SF was replaced with cement in the amounts of 7.5%, 10.0%, and 15.0%. In total, 16 different mix designs were prepared with different SP and SF ratios. In addition, SFb was added to all mixtures of designed concrete at a constant amount of 65 kg/m3. Additionally, a 16-mix design was prepared with SFb. Cumulatively, 32 different mix designs were prepared for the experimental study. Tests on the fresh, hardened, and life-cycle performance properties of the concrete were conducted. As for the metaheuristic part of this study, on the basis of the available experimental data, life-cycle performance parameters of the concrete modified with SF and SFb are predicted by using single and hybrid generalized extreme learning machine methods. Eight different data sets were generated with gradually extended input data. Two different outputs were considered: abrasion resistance (AL) and freezing/thawing (FT). Particle Swarm Optimization (PSO) and Grey Wolf Optimization (GWO) algorithms were used to produce binary and ternary hybrid methods. Four different models were proposed as listed: single use of Generalized Extreme Learning Machine (GRELM), binary use of GRELM-PSO, and GRELM-GWO. Finally, PSO and GWO were hybridized and integrated into GRELM. Two quality indicators, namely Root Mean Square Error (RMSE) and correlation of determination (R2), were considered to see the performance of the prediction. The results showed that the proposed ternary prediction model composed of GRELM-PSO-GWO provided more accurate results in all sets from 74% to 91% by extending input parameters, even if complicated parameters are inserted in as an input to the data set.

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  AtıfScopus28·WoS22·OpenAlex25

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• MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2433
  Field reconnaissance and structural assessment of the October 30, 2020, Samos, Aegean Sea earthquake: an example of severe damage due to the basin effect

  Onat, Onur; Yön, Burak; Öncü, Mehmet Emin; Varolgüneş, Sadık; Karaşin, Abdulhalim; Cemalgil, Selim

  An earthquake with a magnitude ranging from Mw = 6.9 (KOERI) to Mw = 7.0 (USGS) struck Samos Island in the Aegean Sea on October 30, 2020, with an epicentre 70 kms from the İzmir city centre in Turkey. The earthquake took place at 14:51 local time (11:51 UTC). The peak ground acceleration (PGA) of this earthquake was recorded to be 0.179 g at the epicentre of the earthquake. This earthquake occurred at a depth of 17.26 km (AFAD (2020) İzmir Earthquake Report, (In Turkish)) and lasted 16 s. The main shock from the earthquake triggered a tsunami that hit the building stocks built near the coast. During the gradual deregulation of COVID-19 pandemic regulations, various events caused considerable damage to the building stock, particularly in the Izmir Seferihisar and Bayraklı regions and resulted in a massive disruption of daily habits. The main shock caused 117 deaths in both Turkey and Greece, and 1632 people were also injured in Turkey. Moreover, several injuries occurred in Greece. A total of 103 buildings collapsed, 700 were severely damaged, 814 buildings were moderately damaged, and 7889 were slightly damaged. The basic aim of this paper is to briefly present the past and present seismotectonic characteristics of the region, present building stock, and former structural conditions before the earthquake, assess structural performance and classify distinguished earthquake-induced failures and damage due to the basin effect.

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  AtıfScopus30·WoS28·OpenAlex29

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• MakaleAçık Erişim2021Scopus SJRQ1/r/munzur/2581
  24 January 2020 Sivrice-Elazığ, Turkey earthquake: geotechnical evaluation and performance of structures

  Sayın, Erkut; Yön, Burak; Onat, Onur; Gör, Mesut; Öncü, Mehmet Emin; Tuğrul Tunç, Esra; Bakır, Dursun; Karaton, Muhammet; Calayır, Yusuf

  The January 24, 2020 Sivrice-Elazığ (Mw = 6.8) earthquake occurred on the East Anatolian Fault zone. Main shock of this earthquake was occurred 20:55 at local time. The Peak Ground Acceleration was equal to 0.3 g at the epicenter (Sivrice district) of the earthquake. Even though the main shock was moderate, its effects on the structures were rather serious. The main shock caused significant damage and resulted in 41 casualties. 1540 buildings were damaged moderately, while 8519 buildings were damaged heavily and collapsed. This main shock effected four cities surrounded the epicenter due to its shallow earthquakes. The purpose of this paper is to summarize past and present seismic characteristics of the earthquake region. In addition, the aim of this paper is to summarize the seismotectonic of the region, the general characteristics of the earthquake and more specifically to report on the structural damage, and structural damage caused by the earthquake, observed during the site investigation. The damages were classified for reinforced concrete structures, masonry dwellings and non-residential structures. All distinguished earthquake induced failures and damages were discussed. Moreover, lessons learned were presented in this study.

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  AtıfScopus74·WoS68·OpenAlex93

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• MakaleYalnız künye2021Scopus SJRQ3/r/munzur/2530
  Seismicity of East Anatolian of Turkey and Failures of Infill Walls Induced by Major Earthquakes

  Doǧangün, Adem; Yön, Burak; Onat, Onur; Emin Öncü, Mehmet; Saǧlroǧlu, Serkan

  There are three major fault zones in Turkey scattered around the country known as East Anatolian Fault (EAF), North Anatolian Fault (NAF) and Anatolian-Aegean Subduction Zone (AASZ). Last two decades, EAF has been rather quiescent compared with NAF. However, this quiescence was broken in the beginning of the millennium. The strong shaking was started in 2003 with Bingöl earthquake (Mw = 6.3) and the last earthquake on the EAF is the Sivrice-Elazlǧ (Mw = 6.8) on January 24, 2020. Strong seismicity of these faults damaged the structures severely and caused death of the habitants. This study aims to present, seismotectonic of the region, general characteristics of the earthquakes and more specifically to report structural damage of infill walls of the structure's damages caused by these earthquakes. Damage evaluation and identification of the observed infill wall damages due to 2003 Bingöl, 2011 Van earthquakes and January 24, 2020 Sivrice-Elazlǧ earthquake occurred Turkey's Eastern region, were presented, and possible solutions were suggested. Moreover, the effects of the infill walls on the behavior of structures under static and dynamic load cases are discussed that experienced in these earthquakes. Damages are classified according to formations such as in-plane or out-of-plane, evaluations and the results obtained from the discussions are presented for each category.

  AtıfScopus35·WoS32

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• MakaleYalnız künye2021Scopus SJRQ1/r/munzur/2500
  Effect of pumice powder and artificial lightweight fine aggregate on self-compacting mortar

  Etli, Serkan; Cemalgil, Selim; Onat, Onur

  An experimental program was conducted to investigate the fresh properties, mechanical properties and durability characteristics of the self-compacting mortars (SCM) produced with pumice powder and Artificial Lightweight Fine Aggregate (aLWFA). aLWFA was produced by using fly ash. A total of 16 different mixtures were designed with a constant water-binder ratio of 0.37, in which natural sands were partially replaced with aLWFA and pumice powder at different volume fractions of 5%, 10% and 15%. The artificial lightweight aggregates used in this study were manufactured through cold bonding pelletisation of 90% of class-F fly ash and 10% of Portland cement in a tilted pan with an ambient temperature and moisture content. Flowability tests were conducted on the fresh mortar mixtures beforehand, to determine the self-compacting characteristics on the basis of EFNARC. To determine the conformity of the fresh mortar characteristics with the standards, mini-slump and mini-V-funnel tests were carried out. Hardened state tests were conducted after 7, 28 and 56 days to determine the flexural strength and axial compressive strength respectively. Durability, sorptivity, permeability and density tests were conducted at the end of 28 days of curing time. The test results showed that the pumice powder replacement improved both the fresh state and the hardened state characteristics of the mortar and the optimum mixture ratio was determined as 15%, considering other studies in the literature. In the aLWFA mixtures used, the mechanical and durability characteristics of the modified compositions were very close to the control mixture. It is concluded in this study that mixtures with pumice powder replacement eliminated the negative effects of the aLWFA in the mortars and made a positive contribution.

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  AtıfScopus16·WoS15·OpenAlex17

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• MakaleYalnız künye2021Scopus SJRQ1/r/munzur/2411
  Effect of waste textile dye adsorbed almond shell on self compacting mortar

  Cemalgil, Selim; Onat, Onur; Tanaydın, Mehmet Kayra; Etli, Serkan

  The aim of the current experimental study is to investigate the effect of waste textile dye absorbed almond shell on fresh and mechanical characteristics of self-compacting mortar (SCMs). In this context, eight SCMs were designed by substituting Violet Dye Solution adsorbed Almond shell (VDSA) at the rate of 0%, 2.5%, 5.0%, 7.5%, 10.0%, 12.5%, 15.0% and 17.5% as a cement on weight basis including the control mix. To measure the rheological properties of SCMs, mini slump and V-Funnel tests were conducted. A total of 72 beams of 40x40x160 mm3 dimension specimens were casted and immersed in water curing at the end of the 7, 28 and 56 days to determine the mechanical parameters. 48 cubes of 50x50x50 mm3 dimensions were casted and kept in the curing tank to determine durability characteristics such as porosity, sorptivity and specific gravity. Quantitative analyses are also performed by using Scanning Electron Microscopes (SEM), X-ray Diffraction Analysis (XRD), Energy-Dispersive X-ray Spectroscopy (EDS) and Fourier Transform Infrared (FTIR). The experimental results indicated that as the content of VDSA enchases, a remarkable enhancement in flexural strength at early days age and 28 days age strength. Whereas, increasing the content of VDSA resulted in a considerable decrease in compressive strength higher than 5%.

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  AtıfScopus20·WoS16·OpenAlex26

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• MakaleYalnız künye2020Scopus SJRQ1/r/munzur/3826
  Impact of mechanical properties of historical masonry bridges on fundamental vibration frequency

  Onat, Onur

  The fundamental frequency of a historical monument like a masonry bridge or any other structure provides a better and detailed seismic assessment of its demand to provide protection against unexpected seismic ground motion. On this basis, this paper aims to develop an empirical formulation to fit the ambient vibration frequency of historical masonry bridges using a nonlinear regression model. For this purpose, data series were collected from the literature especially focused on both ambient vibration measurement and finite element models of historical masonry bridges modeled on a full scale to get the first global natural frequency. The first approach is to forecast the natural vibration frequency by using only physical characteristics of the historical masonry bridges obtained from the literature-based experimental ambient vibration frequency data. The second approach consists of forecasting the first natural vibration frequency considering the unit weight and elasticity modulus of the dominant construction material based on the homogenization approach. In addition to mechanical characteristics, physical properties of historical masonry bridges were used, such as the length, height, width, and Main Arch Span (MAS) length of the masonry bridge, to predict the first natural vibration frequency. Among the proposed equations, a maximum accuracy of 58% was reached with the literature-based experimental approach. Moreover, an empirical formulation with 81% accuracy was proposed by using both physical characteristics and mechanical properties of the bridges on the basis of finite element model results. Also, this study highlights that this accuracy decreases to 35% if the modulus of elasticity and unit weight are ignored. In addition, the developed formulations are compared with other empirical formulations using the Mean Square Error (MSE), as a measure of the average of the squares of the errors. Consequently, the smallest MSE value of 1.95 was obtained with the proposed equation, whose accuracy was 81% in this study.

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  AtıfScopus17·WoS19·OpenAlex21

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