Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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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: 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.Article Citation - WoS: 24Citation - Scopus: 30Energy Dissipation and Performance Assessment of Double Damped Outriggers in Tall Buildings Under Strong Earthquakes(John Wiley and Sons Inc., 2019) Morales-Beltran, Mauricio; Turan, Gürsoy; Dursun, Onur; Nijsse, RobThe use of a single set of outriggers equipped with oil viscous dampers increases the damping ratio of tall buildings in about 6–10%, depending on the loading conditions. However, could this ratio be further increased by the addition of another set of outriggers? Should this additional set include dampers too? To answer these questions, several double damped outrigger configurations for tall buildings are investigated and compared with an optimally designed single damped outrigger, located at elevation 0.7 of the total building's height (h). Using free vibration, double outrigger configurations increasing damping up to a ratio equal to the single-based optimal are identified. Next, selected configurations are subjected to several levels of eight ground motions to compare their capability for avoiding damage under critical excitations. Last, a simplified economic analysis highlights the advantages of each optimal configuration in terms of cost savings. The results show that, within the boundaries of this study, combining a damped outrigger at 0.5h with a conventional outrigger at 0.7h is more effective in reducing hysteretic energy ratios and economically viable if compared with a single damped outrigger solution. Moreover, double damped outrigger configurations for tall buildings exhibit broader display of optimal combinations, which offer flexibility of design to the high-rise architecture.Book Part Citation - Scopus: 1Hybrid Control of a 3-D Structure by Using Semi-Active Dampers(Springer Verlag, 2014) Turan, GürsoyA base isolated three storey 3-D building is semi-actively controlled not to exceed the maximum allowable base displacement. Large displacements are likely to cause failure in the isolation system, and hence, failure in the superstructure is expected. If a base isolated structure is positioned next to a very long fault line, such as the North Anatolian Fault, the structure will mostly undergo far field type excitations. Near field effects will be seen less occasionally, but design considerations should be made to account for both types of excitations. In case of nearby seismic action, the isolated building should be smart enough to modify its isolation impedance to resist against large ground displacement and velocities. For this study, an isolated three storey building model together with four dampers, which are all placed at the base level, is considered. The dampers have controllable orifices (damping coefficients) and the magnitudes of these damping coefficients are assigned by using a linear quadratic regulator (LQR). During an earthquake excitation, the storey displacements and velocities are used as feedback in the calculation of the optimal control force that is producible by viscous dampers, at each time step. This force, however, is applied only at times when critical displacements and/or velocities occur. The performance of the set of controllers is presented via time simulations of the system for three recorded earthquakes. In addition, these records are time shifted five folds to see the effect of near field action. The results indicate that the control effectively reduces the maximum displacements of the isolation system, while maintaining a reasonable isolation to the superstructure.Article Citation - WoS: 4Citation - Scopus: 5Importance of Static Correction and Damping in the Analysis of a Cable-Stayed Bridge Subjected To Displacement Loading(American Society of Civil Engineers (ASCE), 2017) Hızal, Çağlayan; Turan, GürsoyCable-stayed bridges with long spans are excited by different support vibrations on both sides of the main span. Therefore, a realistic seismic structural analysis of the bridge must involve multiple-support excitation. The dynamic equation of motion, in which all degrees of freedom are solved at once, can be solved directly. A modal analysis might also be possible, but care must be taken with the number of modes used in the analysis. If the ground motion is described in terms of displacement and velocity, which is referred to as displacement loading, then a static correction that will account for the unconsidered higher modes must be performed. In this study, the procedure of multiple-support excitation through the use of modal transformation is explained in detail. The effects of changes in damping levels that affect the analysis results are investigated by using the static correction method in displacement loading. An example is given to illustrate the mentioned problem by using a finite-element model of the cable-stayed Bill Emerson Memorial Bridge.Article Citation - WoS: 11Citation - Scopus: 14Structural Health Monitoring for Bolt Loosening Via a Non-Invasive Vibro-Haptics Human-Machine Cooperative Interface(IOP Publishing Ltd., 2015) Pekedis, Mahmut; Mascerañas, David; Turan, Gürsoy; Ercan, Emre; Farrar, Charles R.; Yıldız, HasanFor the last two decades, developments in damage detection algorithms have greatly increased the potential for autonomous decisions about structural health. However, we are still struggling to build autonomous tools that can match the ability of a human to detect and localize the quantity of damage in structures. Therefore, there is a growing interest in merging the computational and cognitive concepts to improve the solution of structural health monitoring (SHM). The main object of this research is to apply the human-machine cooperative approach on a tower structure to detect damage. The cooperation approach includes haptic tools to create an appropriate collaboration between SHM sensor networks, statistical compression techniques and humans. Damage simulation in the structure is conducted by releasing some of the bolt loads. Accelerometers are bonded to various locations of the tower members to acquire the dynamic response of the structure. The obtained accelerometer results are encoded in three different ways to represent them as a haptic stimulus for the human subjects. Then, the participants are subjected to each of these stimuli to detect the bolt loosened damage in the tower. Results obtained from the human-machine cooperation demonstrate that the human subjects were able to recognize the damage with an accuracy of 88 ± 20.21% and response time of 5.87 ± 2.33 s. As a result, it is concluded that the currently developed human-machine cooperation SHM may provide a useful framework to interact with abstract entities such as data from a sensor network.Article Citation - Scopus: 100Phase Ii Benchmark Control Problem for Seismic Response of Cable-Stayed Bridges(Pitagora Editrice, 2003) Caicedo, Juan Martin; Dyke, Shirley J.; Moon, Seokjun; Bergman, Lawrence A.; Turan, Gürsoy; Hague, Steven T.This paper presents the problem definition for the second generation of benchmark structural control problems for cable-stayed bridges. The goal of this study is to provide a testbed for the development of strategies for the control of cable stayed-bridges. Based on detailed drawings of the Bill Emerson Memorial Bridge, a three-dimensional evaluation model has been developed to represent the complex behavior of the full-scale benchmark bridge. Phase II considers more complex structural behavior than phase I, including multi-support and transverse excitations. Evaluation criteria are presented for the design problem that are consistent with the goals of seismic response control of a cable-stayed bridge. Control constraints are also provided to ensure that the benchmark results are representative of a control implementation on the physical structure. Each participant in this benchmark bridge control study is given the task of denning, evaluating and reporting on their proposed control strategies. Participants should also evaluate the robust stability and performance of their resulting designs through simulation with an evaluation model which includes additional mass due to snow loads. The problem and a sample control design have been made available in the form of a set of MATLAB equations.