Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 11Citation - Scopus: 12An Improved Passive Tuned Mass Damper Assisted by Dual Stiffness(Elsevier, 2023) Roozbahan, Mostafa; Turan, GürsoyA tuned mass damper (TMD) is one of the oldest and most commonly used passive control devices attached to structures to absorb lateral loads of energy from main systems. In the last decades, several novel tuned mass dampers have been designed to increase the performance of TMDs in decreasing the structural responses during excitation vibrations. Moreover, several formulations and numerical optimization methods have been developed to optimize the TMDs parameters. This paper proposes a novel passive tuned mass damper with dual stiffness (DSTMD). The DSTMD includes mass, primary and secondary springs, dashpot, and motion limiting chamber. The performance of DSTMDs depends on their properties such as mass, primary and secondary stiffness, damping coefficient, and the length of the motion limiting chamber. Thus, a metaheuristic optimization algorithm, called the Mouth Brooding Fish algorithm, was used to optimize the DSTMDs parameters. The effectiveness of the optimum DSTMD on two different linear ten-story structures under several earthquakes has been studied and compared with the effectiveness of classical optimum TMDs. According to the study, optimum DSTMDs generally show better effects for certain excitations, and as an average performance, they are superior compared to the classical optimum TMDs in reducing maximum displacement of the buildings. At last, structural yielding is considered, and the performance analysis on this structure shows that the DSTMD has a superior effect in reducing the maximum displacement and is among the best methods for the calculated absolute yielding amount.Research Project Deprem simülatörü (masaüstü)(2007) Turan, Gürsoy; Kınay, GökçeTaşınabilir boyutta ve servo motoru ile çalışan tek boyutlu bir deprem simülatörü imal edilmiştir. Hareketli tabla 40 cm x 40 cm'lik alana sahip olup, 20 kg'lık bir yükü 2g'lik ivme (1g=9.81 m/s2 ) ile hareket edebilmektedir ve en çok 16 cm yer değiştirme imkanına sahiptir. Herhangi bir depremin ivme-zaman verisini okuyan arayüz programı iki girdiyi dikkate almaktadır. Birincisi, benzetilmek istenen deprem hareketin en büyük hızı motorun üretebileceğinden büyük olmamalıdır (25 cm/s). İkincisi, benzer şekilde, depremin en büyük yer değiştirmesi de tablanın hareket sınırlarını (16 cm) aşmamalıdır. Bu değerler aşılıyorsa, istenen hareketin sinyali bir küçültme katsayı ile çarpılmaktadır.Research Project Değişken sönümleme katsayılı amortisörlerin deprem simülasyonu ile üç katlı bir yapıya olan etkisinin değerlendirilmesi(2010) Turan, Gürsoy; Aydın, ErsinBu çalışmada deprem etkisi altında üç katlı bir model yapının yarı aktif olarak kontrollü dinamik davranışı deneysel ve teorik olarak araştırılmıştır. İlk olarak tek yönlü deprem simülatörü üzerine boyutları normal ölçülere göre indirgenmiş üç katlı çelik yapı inşaa edilmiştir. Seçilen model yapının dinamik karakteristikleri önce teorik olarak belirlenmiş daha sonra deneyler ile bulunarak, sonuçların uyumluluğu gözlenmiştir. Yapıyı yarı aktif olarak kontrol edecek olan amortisör, yatlarda kullanılan bir dümen pistonu modifiye edilerek ve bir deşarz hattı eklenerek imal ettirilmiştir. Eklenen deşarz hattına yerleştirilen bir vana ve bu vananın üstüne vanayı kontrol edecek bir step motor monte edilmiştir. Tasarlanan amortisör yarı aktif bir sönümleyici olarak yapının birinci katı ile zemin arasına yerleştirilmiştir. Bu işlemden önce tasarlanan sönüm elemanının matematik modelinin kurulması için amortisör deneyleri yapılmış ve matematik model ortaya çıkarılmıştır. Kontrol işlemi, deşarz hattı üzerindeki vananın açıklığının değiştirilmesi ve bu değişime göre sönümleyici amortisörün sönüm katsayısının değişimi ile gerçekleştirilmiştir. Model yapının deprem etkisi altındaki davranışı amortisörsüz ve amortisörlü olarak deneyler ile test edilmiştir. Ayrıca, amortisörün sönüm özelliği sabit tutularak da deneyler yapılmış ve sonuçlar teorik hesap değerleri ile karşılaştırılmıştır. Yapılan deneyler ve sayısal analizler göstermiştir ki, yarı aktif kontrol edilen amortisör model yapının deprem davranışını oldukça iyileştirmektedir.Article Mesnetlerinden Farklı Yer Hareketlerine Maruz Çok Katlı Çerçevelerin Deplasman Yüklemesine Göre Analizi(Turkish Chamber of Civil Engineers, 2019) Hızal, Çağlayan; Turan, GürsoyIn seismic analysis of structures, generally it is assumed that all supports are subjected to identical ground motions. This approach is assumed to be realistic when the foundation of the structure is formed as a rigid plate, but it cannot consider the dynamic effects of the earthquake wave propagation if the supports are able to move independently. In this study, the multi-support excitation analysis of multi-story, multi bay frames is performed by using displacement loading which defines the seismic load depending on the ground displacement. The modal analysis procedure of the structures subjected to multi-support excitations is given in detail and the effect of pseudo-static displacement on the dynamic response of the structure is highlighted. A static correction approach is implemented with a numerical example to reflect the higher mode effects which are a natural result of displacement loading.Article Citation - WoS: 15Citation - Scopus: 16A Mode Shape Assembly Algorithm by Using Two Stage Bayesian Fast Fourier Transform Approach(Academic Press Inc., 2019) Hızal, Çağlayan; Turan, Gürsoy; Aktaş, Engin; Ceylan, HasanOperational modal analysis may require identifying global modal shapes by using multiple setup measurements. For this purpose, various algorithms have been developed which make use of the Bayesian approach to estimate the global mode shapes. The main motivation of the available Bayesian approaches is based on the estimation of the optimal global mode shape vector directly from Fast Fourier Transform data or assembling the local mode shapes that are identified in the individual setups by using Gaussian approximation. In this study, the two-stage Bayesian Fast Fourier Transform Approach which is originally applied to single setups is implemented to multiple setup problems for well separated modes. Analytically it is shown that the resulting formulation is the same for the mode shape assembly by using the Gaussian approximation. In addition, the weights of individual setups in the global mode shape vector is analytically calculated which depend on the Hessian matrix for local mode shapes. To validate the proposed methodology, a numerical example that considers setup-to-setup variability of modal signal-noise ratios is presented. For comparison purposes a ten-story shear frame model is experimentally investigated, and the measurements of a benchmark bridge structure are considered in the verification of the current procedure. (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 5Pre-Identification Data Merging for Multiple Setup Measurements With Roving References(Springer Verlag, 2020) Ceylan, Hasan; Turan, Gürsoy; Hızal, ÇağlayanOne-time operational modal analysis (OMA) of large civil structures requires measurements of the vibrations, which, according to the number of channels to be measured, are generally expensive and arduous to obtain. In this study, identification of modal parameters of civil structures has been investigated by using multiple setups with a roving reference channel. In this manner, a limited amount of equipment becomes sufficient for OMA of structures. The procedure consists of a transformation function between measurement setups, which transforms all measured data to the time frame of a selected reference setup. To illustrate the procedure, an existing 10 story laboratory shear frame model is considered. A numerical and an experimental investigation have been carried out to identify its modal characteristics. The validity of the procedure has been explained in detail by making use of a coherence function in-between the multi-setup measurements. According to the results, OMA by using only a few sensors with the performed procedure can be equivalent to OMA by using a full measurement setup. Against a common believe, the results of this study reveal that synchronization among the setups does not prominently affect the identification results.Article Citation - WoS: 29Citation - Scopus: 29A Two-Stage Bayesian Algorithm for Finite Element Model Updating by Using Ambient Response Data From Multiple Measurement Setups(Academic Press, 2020) Hızal, Çağlayan; Turan, GürsoyThis study presents a two-stage Bayesian finite element model updating procedure by using acceleration response measurements obtained from multiple setups. In the presented methodology, parametric uncertainties for the modal parameters are estimated by using the Bayesian Fast Fourier Transform Approach (BFFTA). Different from the previous Bayesian methods, a block diagonal covariance matrix is modeled for prior estimation of measured modal parameters. In addition, the modelling error in the eigenvalue equations is considered as soft constraints to be updated. Numerical and experimental studies are presented to validate the proposed method. The effect of soft constraints on the identification results as well as their posterior uncertainties are investigated. According to the results, it is shown that the proposed methodology can identify the most probable finite element model parameters with high level of accuracy. In addition, the posterior uncertainties obtained by the proposed procedure are significantly small when compared to the methods that consider rigid constraints for prediction and/or modelling error. (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2Effect of Seismic Wave Velocity on the Dynamic Response of Multi-Story Structures on Elastic Foundation(Elsevier Ltd., 2018) Hızal, Çağlayan; Turan, GürsoyTraveling wave effects are generally considered with three main cases: (i) Wave passage effect that results with time delay in earthquake motion. (ii) incoherence effect which is defined as loss of coherency in the ground motion due to the reflection and refraction of waves, and (iii) local site effects. For multi-story structures whose supports are close to each other, the incoherence and local site effect may be omitted. In this case, traveling waves result only in a pure time delay in the earthquake motion (wave passage effect). Due to the wave passage effect of vertical and/or horizontal ground motion, the superstructure needs to be analyzed by multi-support excitation. Raft foundations cannot constrain vertical deformations and/or rotations, but they cause a diaphragm effect in the horizontal direction which results in uniform excitation. In this study, the effect of vertical earthquake motions onto multi-story buildings on elastic soil is investigated. Multi support excitation is considered by using displacement loading, which defines the equivalent seismic loads in terms of the ground displacement. According to the performed simulations of the selected structures, it is shown that structural height has a direct influence that results in member force magnifications with slow traveling wave effect. Among these, the ground floor column axial forces are most affected.Article Citation - WoS: 27Citation - Scopus: 32Distribution of Strong Earthquake Input Energy in Tall Buildings Equipped With Damped Outriggers(John Wiley and Sons Inc., 2018) Morales-Beltran, Mauricio; Turan, Gürsoy; Yıldırım, U.; Paul, JoopThe seismic design of optimal damped outrigger structures relies on the assumption that most of the input energy will be absorbed by the dampers, whilst the rest of the structure remains elastic. When subjected to strong earthquakes, nevertheless, the building structure may exhibit plastic hinges before the dampers begin to work. In order to determine to which extent the use of viscously damped outriggers would avoid damage, both the host structure's hysteretic behaviour and the dampers' performance need to be evaluated in parallel. This article provides a parametric study on the factors that influence the distribution of seismic energy in tall buildings equipped with damped outriggers: First, the influence of outrigger's location, damping coefficients, and rigidity ratios core-to-outrigger and core-to-column in the seismic performance of a 60-story building with conventional and with damped outriggers is studied. In parallel, nonlinear behaviour of the outrigger with and without viscous dampers is examined under small, moderate, strong, and severe long-period earthquakes to assess the hysteretic energy distribution through the core and outriggers. The results show that, as the ground motion becomes stronger, viscous dampers effectively reduce the potential of damage in the structure if compared to conventional outriggers. However, the use of dampers cannot entirely prevent damage under critical excitations.Article Citation - WoS: 1Citation - Scopus: 1Kablolu Bir Köprünün Deprem Davranışının Μ-sentezli Aktif Kontrolü(TMMOB İnşaat Mühendisleri Odası, 2009) Turan, Gürsoy; Voulgaris, Petros; Bergman, Lawrence A.Bu çalışmada çeşitli kontrol algoritmalarının etkinliğini birbiriyle karşılaştırmak amacıyla oluşturulmuş bir kablolu köprü kontrol model örneği [1, 2] baz alınmıştır. Köprünün sonlu elemanlar modeli modal önem sırasına göre küçültülerek 1/6 boyutunda bir kontrol tasarım modeli elde edilmiştir. Köprünün deprem hareketi sırasındaki kritik noktaları dikkatle gözlenmiş, ve yol seviyesinde kule kesme kuvvetlerinin oluştuğu noktaların kontrolü en zor noktalar olduğunu ortaya konmuştur. Kontrol amaçlı olarak hidrolik pistonlar kullanılmıştır. Belirsizliği tolere edebilen bir tasarım önerisiyle, tasarım modeli ile değerlendirme modeli arasındaki fark sınanmıştır. Ayrıca μ-sentezi esas alınarak bir kontrol denklemi kurgulanmıştır ve bununla birlikte davranış benzetimi gerçekleştirilmiştir.