İnşaat Mühendisliği Bölümü Koleksiyonu

Bu koleksiyon için kalıcı URI

https://hdl.handle.net/20.500.12428/2661

Listeleniyor 1 - 20 / 25

Prescreening of Sedimentation Potential in Harbor Approach Channels: A Parametric Model
(Asce-Amer Soc Civil Engineers, 2025) Baysal, Selman; Kırca, V. Ş. Özgür
In this study, a parametric model was developed to prescreen the sedimentation potential and maintenance dredging frequency for harbor approach channels under the action of combined current and nonbreaking waves. The model is fast, easy to implement, and well-suited for preliminary assessment for a given set of ship, metocean, and sediment characteristics. To resolve the velocity profile, a refined wave-altered current profile was implemented in the model in favor of a simple power-law current profile, which improved the model performance substantially. The model was first validated against the results reported in an experimental study, and then verified against field measurements of the Damietta Harbor approach channel. Finally, a parametric study was conducted to investigate the influences of (1) median grain size of seabed sediment, (2) wave severity, and (3) depth-averaged current velocity on the sedimentation in approach channels. The results showed that the dredging frequency of approach channels is mainly governed by the wave characteristics, i.e., wave severity, in the case of combined waves and current. It was further shown that representing the wave-altered current profile in simplified models is particularly important. Otherwise, the model would yield unrealistically high dredging frequencies when the current velocity approaches zero, even under severe waves.
Tek Boyutlu Zemin Büyütme Analizlerinde Transfer Fonksiyonunun Değiştirilmiş Sonlu Elemanlar Taşıma Matrisi Yöntemi ile Elde Edilmesi
(Afet ve Acil Durum Yonetimi Baskanligi (AFAD), 2021) Bilican, Öznur; Bozdoğan, Kanat Burak; Keskin, Erdinç
In this study, a method is proposed to obtain Transfer functions used in one-dimensional soil amplification analysis. Within the scope of the study, the Modified Finite Element Transfer Matrix (MFETM) method, which was used to find the soil fundamental period in the literature, was adapted to the problem of finding transfer functions used in soil amplification analysis. In the classical finite element method, the system matrix size that increases depending on the number of elements is independent of the number of elements in the MFETM method. At the end of the study, the suitability of the proposed method was shown on two examples. The examples discussed were solved using both the MFETM method presented in this study and the method in the literature, and the results were compared. A program was written in Scilab for the application of the presented method.
Development and validation of a degree of saturation prediction model using time domain reflectometry for compaction control
(Elsevier, 2023) Özgür, Mehmet
Compaction quality is directly related with the shear strength of soils. Inadequately compacted soils have lower shear strength that decrease the load bearing capacity and increase the differential settlement of the pavement, which may endanger safety and durability of the highways. Although intelligent compaction technology has enhanced the quality control of the compaction, conventional evaluation methods adopting sampling from random locations to determine relative compaction are extensively used in most of the earthwork projects. However, relative compaction may lead misjudgment, since the compaction energy level and the soil type inplace cannot match exactly with the given specifications of an earthwork project. Recent studies have shown that soil degree of saturation (Sr) can be utilized as an alternative control parameter for compaction quality. Sr inplace is usually determined with sand cone method. The method is time consuming as well as prone to error due to potential water seepage and deformation of soft soils. With its ability to provide remote and continuous monitoring in real time, Time Domain Reflectometry (TDR) has the potential to serve as a viable alternative method for determination Sr in-place. This research presents models developed using different calibration methods for the prediction of Sr with TDR measured dielectric permittivity. The accuracy of the models was evaluated with cross-validation. The results show that TDR is able to predict the Sr with less than & PLUSMN;5% deviation for 93% of the specimens in the validation set within the saturation ratio range of 0.01-0.93 cm3 cm-3 with an appropriate model.
A Method for Determining the Fundamental Site Period and the Average Shear Wave Velocity
(World Scientific Publ Co Pte Ltd, 2024) Bozdoğan, Kanat Burak; Keskin, Erdinç
The soil-structure interaction plays a crucial role in determining the displacement and internal forces of multi-story buildings subjected to strong ground motion. One of the critical dynamic characteristics influencing soil-structure interaction is the fundamental site period and the average shear wave velocity associated with it. This study introduces an original equation to determine these parameters. In addition, for the first time in the literature, the version of the Rayleigh method used for finding the fundamental periods of buildings is used to find the fundamental site period. The soil is modeled as an equivalent shear beam to obtain the proposed equation. The peak displacement is obtained by acting the soil mass as an external load on the equivalent shear beam. For single-layer soil, the fundamental site period is proportional to the square root of the peak displacement of the equivalent shear beam. The least squares method generalizes the proposed relation for single-layer soils to multi-layer soil profiles. Modified Finite element Transfer matrix method is used for calibration in the least squares method. The equations used in the literature and earthquake codes for determining the fundamental site period and average shear velocity are tested on various examples, and it is shown that the method proposed in this study, along with the Rayleigh method, gives better results than these equations. The performances of these two methods and the five commonly used equations are tested and compared on different soil profiles. Transfer functions, Finite Element Method (SAP200) and Modified Finite Element Transfer Matrix Method are used for verification. For all soil profiles, the results obtained from the transfer function, Finite Element Method (SAP200) and Modified Finite Element Transfer Matrix Method are found to be in agreement. The true percent relative error found in the results obtained with the proposed method is 4.47%.
A Practical Method for Determining Dynamic Characteristics of Buildings Under the Effect of Foundation Rotations
(World Scientific Publ Co Pte Ltd, 2024) Bozdoğan, Kanat Burak; Keskin, Erdinç; Öztürk, Duygu
In multi-storey buildings, unforeseen foundation rotations can change the building's behavior. Therefore, these effects should be taken into account in the analysis. In the studies conducted in the literature, the impact of the rotation of the foundation on the building behavior under static loads has been investigated. In this study, an approach is proposed to determine the dynamic behavior of buildings under the effect of foundation rotation, regardless of the type of bearing system. The multi-storey building was modeled as an equivalent flexural-shear beam in the study. In the study, the axial displacements of the columns, which are neglected in the flexural-shear beam model, are also considered, which is different from the literature. The equation of motion representing the dynamic analysis of the equivalent flexural-shear beam was solved with the help of the Differential Transform Method. The period coefficients, effective mass ratio and peak displacement coefficient for five cases were determined and plotted. A code was prepared using Matlab for the analysis with the Differential Transform Method. As a result of the study, the dynamic characteristics obtained depending on the dimensionless building behavior coefficient have been graphed. Using the given graphs, the dynamic characteristics of the buildings under the effect of foundation rotation can be determined quickly and practically. The method presented in this study can be used for Response spectrum analysis of all systems with pure shear beam, pure bending beam and bending-shear beam behavior. In addition, an approach has been proposed to consider P - Delta effects within the scope of the study. The results obtained in the study were interpreted, and the impact of rotation on dynamic characteristics was discussed. At the end of the study, for the convenience of the presented method, two examples, one for wall-frame and the other for frame systems, were solved with the proposed method, and the results were compared with the SAP2000 program.
A Method for Determination of Moment Contribution Ratio under Foundation Rotation in Shear Wall-Frame Systems
(Mdpi, 2024) Bozdoğan, Kanat Burak; Keskin, Erdinç
In shear wall-frame systems, the foundation rotation that may occur under the shear walls changes the displacements and interstory drift ratios and changes the internal force distribution. This study investigates the effect of foundation rotations under shear walls on internal force distribution in shear-frame systems. The originality of the study lies in considering parabolic loads and dynamic analysis (first mode), in addition to static uniform or triangular distributed loads, when determining the shear wall moment contribution ratio under the influence of foundation rotation. The shear wall contribution ratio, a key parameter in many earthquake codes, is defined as the ratio of the sum of bending moments taken by the shear walls at the base to the overturning moment. It plays a crucial role in determining the building's behavior. Depending on this ratio, the load-reduction coefficient is changed. This study investigates the effect of foundation rotation on the moment distribution at the base for three different static load cases and the first mode in the dynamic analysis. The multi-story building is modeled as an equivalent sandwich beam. The moment contribution ratio (MCR) was calculated with the help of analytical solutions of the differential equations written for three different load cases in static conditions, and graphs were created for practical use directly calculating the MCR. In the methodology of the study, the initial step involves the calculation of the equivalent sandwich beam stiffness parameters and the foundational rotational spring. Subsequent to these calculations, the MCR values can be directly obtained with the help of graphs. This approach facilitates the rapid and practical determination of the MCR and can be used in the preliminary sizing phase to eliminate possible errors in the data entry of software that performs detailed analysis. In addition, in the presented study, it has been shown that taking a single mode into account is sufficient when calculating MCR values in dynamic analysis.
Static, Dynamic and Stability Analysis of Tall Buildings by the Transfer Matrix Method Using Replacement Timoshenko Beam
(Springer Int Publ Ag, 2024) Cruz, Mao Cristian Pinto; Bozdoğan, Kanat Burak
In this study, an approach is proposed for the analysis of structures that can be represented by the Timoshenko beam model. In this study, the Transfer matrix method, which has been previously developed in the literature for static, dynamic and stability analysis of all types of multi-story buildings, is formulated in this study specifically for the analysis of symmetric buildings consisting of only shear walls or only frames, which can be represented behaviorally as Timoshenko beams. The size of the Transfer matrix, which is 6*6 in the literature by considering all effects in the symmetric state, is obtained as 4*4 due to the characteristics of the systems considered in this study. In the study, firstly, the differential equation system and boundary conditions representing the Timoshenko beam model were obtained in accordance with Hamilton's principle. Then, the element Transfer matrix was obtained by solving the obtained differential equation system. With the presented approach, both static, dynamic and stability analysis can be performed. The most important advantage of the presented method is that the sizes of the matrices used in the analyses are small. With the Transfer matrix method, the size of both the element and the system Transfer matrix is 4*4. At the end of the study, to show the suitability of the presented method with the finite element method, two examples, one consisting of pure walls and the other consisting of pure frames, were solved with the presented approach and the results were evaluated.
What psychological and socio-demographic factors can influence people's intention to use ridesharing during the war? A case study in Ukraine
(Elsevier Sci Ltd, 2025) Dadashzadeh, Nima; Volkova, Natalia; Ekmekçi, Mustafa; Horpenko, Daniil; Woods, Lee; Nikitas, Alexandros
Public transport services can be disrupted by natural or human-made crises, such as the recent war in Ukraine. Ridesharing has the potential to be used as an alternative to public transport during such crises. However, peoples' attitudes and intentions towards ridesharing during war has not been studied. This study aims to address this critical gap by collecting and analysing travel behaviour data in two Ukrainian cities: Kyiv and Odessa. Exploratory factor analysis identified ten factors influencing ridesharing, namely: attitudes, perceived behavioural control, subjective norm, ease of use, usefulness, moral norms, trust, perceived safety, emotions, and discrimination. Then, a combined conceptual model based on the Theory of Planned Behaviour, and the Technology Acceptance Model was proposed, to incorporate potential psychological and socio-demographic in the context of a war situation. Structural equation modelling was used to explore the causal relationships between these factors and ridesharing. In the context of war, perceived 'usefulness' affected attitudes, while perceived 'ease of use' influenced perceived behavioural control. Moral norms strongly impacted the ridesharing intention; trust influenced attitudes; and gender played a major role by indirectly affecting ridesharing intention. This can provide transport planners and policy-makers with insights as to how ridesharing can be more attractive and become a genuine tool for enhancing human mobility resilience.
A practical modification to coaxial cables as damage sensor with TDR in obscured structural members and RC piles
(Techno-Press, 2023) Özgür, Mehmet; Arsoy, Sami
Obscured structural members are mostly under-evaluated during condition assessment due to lack of visual inspection capability. Insufficient information about the integrity of these structural members poses a significant risk for public safety. Time domain reflectometry (TDR) is a novel approach in structural health monitoring (SHM). Ordinary coaxial cables as is without a major modification are not suitable for SHM with TDR. The objective of this study is to propose a practical and cost-effective modification approach to commercially available coaxial cables in order to use them as a cable sensor for damage detection with the TDR equipment for obscured structural members. The experimental validation and assessment of the proposed modification approach was achieved by conducting 3-point bending tests of the model piles as a representative obscured structural member. It can be noted that the RG59/U-6 and RG6/U-4 cable sensors expose higher strain sensitivity in comparison with non-modified as is versions of the cables used. As a result, the cable sensors have the capability of sensing both the presence and the location ofa structural damage with a maximum aberration of 3 cm. Furthermore, the crack development can be monitored by the RG59/U-6 cable sensor with a simple calibration.
Hasar Görebilirliğin Hakim Periyoda Bağlı Belirlenmesi İçin Bir Yaklaşım: Çanakkale İl Merkezi Örneği
(2024) Bozdoğan, Kanat Burak; Aktan, Selen
Hasar görebilirliğin önemli bir göstergesi göreli kat ötelemesi değeridir. 0.01 göreli kat ötelemesi sınırı ATC-40’a göre hemen kullanım performans seviyesine karşılık gelmekte olup, bu göreli kat ötelemesi sınır değerinin altında binalar elastik davranış göstermektedirler. Bu çalışmada, Çanakkale il merkezindeki düzenli betonarme binaların hasar görmemeleri için hakim periyot değerlerinin hangi aralıklarda olması gerektiği belirlenmiştir. Çalışma; ZC, ZD ve ZE zemin sınıflarında ve DD-1 ve DD-2 deprem düzeyleri için gerçekleştirilmiştir. Bu kapsamda, maksimum göreli kat ötelemesi oranının belirlenmesi için salt perdeli yapılar için eğilme kirişi kabulü yapılırken, salt çerçeveli yapılar için kayma kirişi kabulü yapılmıştır. Çalışmada literatürden farklı olarak daha gerçekçi sonuçlar elde etmek için eğilme kirişi ve kayma kirişi modelinde kütleler ayrık olarak kat hizalarında dikkate alınmıştır. Bu modelden yararlanılarak maksimum göreli kat ötelemesi oranı için hakim periyoda bağlı bir bağıntı SAP2000 programı yardımıyla elde edilmiştir. Elde edilen bağıntı 0.01 göreli kat ötelemesi değerine eşitlenerek binaların hasar görmemesi için gereken minimum hakim periyot değerleri hesaplanmıştır. Elde edilen sonuçlar grafik ve tablolar üzerinde gösterilerek sonuçlar yorumlanmıştır.
Seismic Risk Evaluation of Existing Reinforced Concrete Buildings: A Case Study for Çanakkale-Türkiye
(Çanakkale Onsekiz Mart University, 2024) Benek, Muhammed; Aktan, Selen
Türkiye is in an important earthquake zone, and most of the population is under seismic hazard. The high loss of lives in the past earthquakes indicates that our existing building stock is vulnerable. In this study, a field survey was carried out to determine the existing earthquake risks of reinforced concrete buildings in İsmetpaşa, Barbaros, Cevatpaşa, Kemalpaşa, Namıkkemal, Esenler, and Fevzipaşa Neighborhoods of Çanakkale city center. This study was conducted to specify the regional distribution of risky buildings to be examined by the street survey method called \"Simplified methods that can be used to determine the regional risk distribution of buildings\" in the implementation regulation of Law No. 6306. For this purpose, 585 reinforced concrete buildings were examined with this method, and the earthquake performance scores of these buildings were determined. The performance scores calculated as a result of reflecting the number of stories, earthquake hazard zone, type of structural system, and structural irregularities of the buildings were evaluated based on different parameters. It was seen that soft stories with values ranging from 50% to 100% and heavy overhangs with values ranging from 37% to 63% were the most common irregularities in existing buildings in Çanakkale.
Betonarme Çerçeve ve Kolonlarda İtme Analizi
(Çanakkale Onsekiz Mart University, 2024) Özkarabulut, Aydın; Köksal, Hasan Orhun
Bu makale, 1950'lerden bu yana betonarme çerçeve ve kolonların karmaşık davranışlarının modellenmesine yönelik devam eden deneysel ve analitik çalışmaların, günümüz yönetmeliklerindeki statik itme analizlerine olan etkileri üzerine odaklanmıştır. Bu noktada yapı elemanlarının moment eğrilik ilişkilerinin analizlere gerçekçi bir şekilde yansıtılması, davranışı belirleyici nitelik taşımaktadır. Bu çalışmada, Koksal-Erdogan tarafından önerilen çok eksenli basınç altındaki beton davranış modeli kullanılarak geliştirilen bir program aracılığıyla elde edilen moment-eğrilik ilişkileri, analizlerde kullanılmıştır. Geliştirilen yapısal analiz programı ise, tek açıklıklı ve tek katlı boş betonarme çerçeve ile ankastre tekil kolonların deneysel olarak belirlenmiş davranışlarını tahmin etmekte kullanılmıştır. Yapılan analizlerin sonucunda, deney çerçeve ve kolonlarına ait yatay deplasmanlar ve kuvvetlerin, Koksal-Erdogan modeli ile birlikte karşılaştırmalı bir şekilde Mander modelinden elde edilen moment-eğrilik diyagramları kullanılarak başarıyla tahmin edilebildiği belirlenmiştir. Makalede ayrıca, Mander modeli ile Koksal-Erdogan modeli arasında gerilme-şekildeğiştirme ilişkileri bakımından da karşılaştırmalar yapılmış ve sonuçların oldukça uyumlu olduğu ancak Koksal-Erdogan modelinin biraz daha düşük gerilme değerleri verdiği belirtilmiştir. Geliştirilen moment-eğrilik programının geçerliliğini göstermek amacıyla, literatürde bulunan SEMAp programıyla bazı karşılaştırmalar yapılmış ve iki program arasında benzer sonuçlar elde edildiği belirlenmiştir. Koksal ve Mander modellerine göre incelenen kolonlar ve çerçeve için elde edilen iç kuvvet şekil değiştirme tahminlerinin, deney sonuçlarıyla uyumlu olduğu gözlenmiştir.
Beton Yüzey Çatlaklarının YOLOv8 Derin Öğrenme Algoritması ile Tespit Edilmesi
(Çukurova Üniversitesi, 2024) Altun, Muhammet Gökhan; Altun, Ahmet Hakan
Beton kullanım ömrü boyunca takip edilmeli, varsa hasarlar tespit edilmeli ve gerekli işlemler zamanında yapılmalıdır. Bundan dolayı doğru zamanda doğru tespit betonun dayanıklılığı açısından oldukça önemlidir. Çatlaklar, betonarme yapıların zarar gördüğünün en erken sinyalleridir. Türkiye gibi deprem riski yüksek bölgelerde yapıların dayanıklılığı ve güvenliği açısından çatlakların erken tespiti hayati öneme sahiptir. Çatlakları manuel olarak tespit etmek genellikle zaman, işgücü, maliyet, yüksek hata olasılığı ve uygulamadaki zorluklar açısından oldukça dezavantajlıdır. Manuel tespite alternatif olarak görüntü işleme teknikleri, makine öğrenmesi ve derin öğrenme tabanlı algoritmaların bu alanda kullanımı yaygınlaşmaktadır. Bu çalışmada, Orta Doğu Teknik Üniversitesi kampüsündeki farklı binalardan elde edilen görüntülerden oluşan METU veri kümesi kullanılarak beton yüzeyindeki çatlakların görüntü işleme yöntemi ile tespit edilmesi amaçlanmıştır. Veri kümesinden 550 adet örnek görüntü seçilmiş olup bu görüntülerin 500 adedi pozitif, kalan 50 adedi ise negatif görüntüden oluşmaktadır. Veri seti çeşitli veri artırma teknikleri ile 1330 örneğe genişletilmiştir. Veri seti %88 eğitim, %8 doğrulama, %4 test kümesi olarak bölünmüştür. Sonuç olarak 1170 adet görüntü eğitim, 105 adet görüntü doğrulama ve 55 adet görüntü ise test için kullanılmıştır. Eğitim işlemi Google Colab ortamında gerçekleştirilmiştir. Model olarak YOLO serisinden YOLOv8 modeli kullanılmıştır. Elde edilen sonuçlara göre modelin çatlak tahminlerinde çok az yanlış pozitif sonuç verdiği ve farklı sınıfları ayırt etmede yüksek başarı gösterdiği tespit edilmiştir.
Numerical Investigation of the Interacted Behavior of Embankment-Slope System Under Seismic Loading Conditions
(Springer Nature, 2024) Akbay Arama, Zülal; Akın, Muhammed Selahaddin; Dalyan, İlknur; Gençdal, Hazal Berrak
In this study, the integrated effects of the geometrical characteristics of slope and the geotechnical strength properties of clayey foundation soils are investigated, considering the relative distance of the embankment from the slope edge under dynamic loading conditions with performing numerical analysis. In this context, a finite-element-based two-dimensional commercial software is used to perform pseudo-static analysis concerning the consideration of the Samos-İzmir earthquake in October 2020. The outcomes of the studies were evaluated in terms of the determining factor of safety values to interpret the effects of the envisaged variants on stability.
Stress-strain model for high-strength concrete tied columns under concentric compression
(Elsevier Ltd, 2021) Köksal, H.O.; Erdoğan, A.
Providing accurate constitutive stress–strain relationships for confined concrete can increase the reliability of the moment curvature (MC) analyses in the displacement-based seismic design of reinforced concrete (RC) columns. This paper presents a new stress–strain model for high-strength concrete (HSC) tied square columns which exhibit a more brittle behavior than normal strength concrete (NSC) members. Introducing the concept of least confined volume in the damage localization zone at the middle of the concrete core, a new approach is developed for the confinement stress distribution of lateral ties. In order to determine the lateral stresses acting on the vertical surfaces of the least confined volume, the effective confinement stresses are reduced considering the tie configuration. The peak strength and the ductility of the column should therefore be calculated for the confined concrete in this region. A concrete failure criterion applicable to multi-axial compression due to the reduced confinement stresses in two orthogonal directions, is then used to determine the ultimate strength of HSC columns. Moreover, plotting the compression meridian of the failure criterion, a simple and design-oriented formula is proposed for the ultimate strength of HSC tied columns. The validity of the proposed approach and the performances of two well-known analytical models are verified against the test results of eighty-six HSC columns from five different experimental studies for both the axial stress–strain behavior and the ultimate strength. Besides, the implementation of the concept of the reduced confinement stress in the Mander's model leads to a significant improvement in its capability of predicting the triaxial strength of HSC.
Hydrogeochemical Assessment of Groundwater for Drinking and Agricultural Use: A Case Study of Rural Areas of Alwar, Rajasthan
(Springer, 2021) Aggarwal, Ankur; Soni, Jigyasa; Sharma, Khyati; Sapra, Mohnish; Karaca, Öznur
Groundwater contributes substantially to the development of arid and semi-arid regions around the globe. The present study integrates groundwater quality and its suitability for drinking and irrigation around Alwar city of Rajasthan state, where agriculture is the major land use. The application for drinking was assessed by comparing the observed value with prescribed standards of WHO. Groundwater was found suitable for drinking at most of the locations. The suitability of groundwater for irrigation was determined by calculating ion-based ratios and comparing them against the suggested ratios and indices for agricultural quality. Suitability for irrigation was assessed against electrical conductivity (EC), percentage sodium (%Na), residual Na2CO3 (RSC), per cent soluble sodium (SSP), sodium adsorption ratio (SAR), Mg hazard and permeability index (PI) etc., and the quality was compromised for EC, %Na and Mg Hz. Since the soil was sandy, the groundwater was found suitable for irrigation over long-term use, with the only problem of magnesium hazard. Based on the different ratios of anions and cations, silicate weathering was observed to be regulating groundwater chemistry, and the groundwater belonged to mixed CaMgCl and CaHCO3− type based on Piper’s classification and relative abundance of ions. Further, meteoric genesis classification showed that the groundwater in the study region had direct base exchange and shallow meteoric water percolation. Presence of kaolinite and quartz minerals in soil confirmed that silicate weathering is the major process controlling groundwater chemistry.
Spatial and Seasonal Variability of Long-Term Sea Surface Temperature Trends in Aegean and Levantine Basins
(Springer, 2021) Saraçoğlu, Fevziye Ayça; Aydoğan, Burak; Ayat, Berna; Saraçoğlu, Kebir Emre
This study aims to estimate the spatial variability of the long-term trends of Sea Surface Temperature (SST) in the Eastern Mediterranean Sea including the Aegean Sea for 39 years between 1982 and 2020. Two datasets consisting of in-situ daily mean SSTs provided by the Turkish State Meteorological Service for the 12 stations located along the Aegean and Levantine coasts of Turkey and gridded daily mean Optimum Interpolation Sea Surface Temperature version 2.1 (OISSTv2.1) data obtained from the National Centers for Environmental Information (NCEI) of the United States National Oceanic and Atmospheric Administration (NOAA) are used for this aim. The trend of change in SST is computed using a non-parametric Theil-Sen estimator methodology. The significance of trends is computed using the Mann–Kendall test. As well as the long-term trends of monthly mean SST, the trends of monthly minimum and maximum SSTs are analyzed to reveal the long-term variations of extreme SSTs. It is concluded that there is a statistically significant upward trend within the study area. The annual basin-averaged upward trends of monthly mean, minimum, and maximum SSTs are estimated as 0.039 °C/year, 0.043 °C/year, and 0.037 °C/year, respectively. Coastal in-situ data present different characteristics for the Aegean Sea and the Levantine Basin. Aegean Sea stations show that the annual maximum SST has a higher rate of upward trend than the annual mean and minimum SSTs, while measurements from the Levantine Basin show minimum SST values increasing at a greater rate than both the annual means and maximums. Analysis of in-situ data at 12 stations provides statistically significant trends between 0.024 °C/year and 0.055 °C/year, 0.025 °C/year and 0.093 °C/year, and 0.031 °C/year and 0.071 °C/year for annual mean, annual minimum, and annual maximum SSTs, respectively. Seasonal analysis of the monthly mean SST trends shows that the highest upward trend occurs in August at the Dikili station (Aegean Sea) with a rate of 0.110 °C/year. SST in the study area is significantly affected by the Atlantic Multidecadal Oscillation (AMO), Eastern Atlantic (EA), and East Atlantic/West Russia (EA/WR) indices.
A Hand Method for Assessment of Maximum IDR and Displacement of RC Buildings
(Springer Science and Business Media Deutschland GmbH, 2023) Bozdoğan, Kanat Burak; Özturk, Duygu
Maximum displacement and the maximum interstorey drift ratio are the important factors for the measurement of the vulnerability of multistorey buildings. For this reason, in this paper a method was proposed to calculate the maximum displacement and maximum interstorey drift ratio (IDR) values. In this model, reinforced concrete multistorey structure was modeled as an equivalent flexural-shear frame. Maximum displacement and the maximum IDR were calculated according to the Equivalent Static Loads Method and The Response Spectrum Method using the continuum model and the results were tabulated. With the help of the obtained tables by this study, the maximum displacement and the maximum IDR of the regular multistorey structures can be calculated quickly and practically. The axial deformation of the vertical elements (columns and shear walls) were approximately considered in the study. The convergence of the presented method to the Finite Elements Method was investigated by two examples in the last part of the study.
Single and Multi Effects of Polycarboxylate Main and Side Chain Lengths on Setting Time, Viscosity, and Yield Stress of Cementitious Mixtures Containing Fly Ash
(American Society of Civil Engineers (ASCE), 2023) Altun, Muhammet Gökhan; Özen, Süleyman; Karakuzu, Kemal; Mardani, Ali; Ramyar, Kambiz
In this study, polycarboxylate polymers having different main chain lengths, side chain lengths, and main chain and side-chain lengths at constant molecular weight were synthesized. Cementitious mixtures with 0%, 15%, 30%, and 45% fly ash substitution levels were tested with polycarboxylate based admixtures (PCEs). As the main and side chain length of the PCE increased up to a certain value, regardless of the fly ash content, the fluidity of the mixtures was positively affected. However, after a certain length, both the electrostatic and steric effects of the PCE decreased, as the polymers intercalated and flocculated, adversely affecting the flow properties of the mixtures. Regardless of the PCE structure, the use of fly ash adversely affected the setting times and rheological properties of the mixtures.
Utilization possibilities of steel slag as backfill material in coastal structures
(Nature Research, 2023) Tozsin, Gülşen; Yonar, Fatih; Yücel, Onuralp; Dikbaş, Atilla
The aim of this study is to investigate the utilization possibilities of steel slags, basic oxygen furnace (BOF) and electric arc furnace (EAF) slags, as backfill material in coastal structures. Within the scope of the study, physical, mechanical and chemical properties of the steel slags were investigated and their potential to create environmental risks were evaluated. The results showed that soundness loss and filler content ratio were below the limit values for steel slags to be used as backfill material. It was determined that the density, porosity, water absorption and Los Angeles abrasion ratios of steel slags were generally higher than natural aggregates. In order to reach the California Bearing Ratio (CBR) limit (> 25%), the maximum particle size of the steel slag was reduced to 25 mm. In this particle size, CBR of the slag samples generally gave better results compared to the natural aggregate (38%), except for Kardemir and Asil samples. In addition, the concentration values of heavy metals (Cu, Cd, Cr, Pb, Ni, Zn, Hg and As) were below the limit values specified in the regulation. It is suggested that EAF slags should be aged for at least 6 months and BOF slags for at least 24 months in open air conditions before being used as backfill material in coastal structures after the maximum particle size is reduced to 25 mm.

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