Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2026Effects of earthquake frequency content and isolation thickness on seismic behavior of a structure system resting on geotechnical seismic isolation layer
Ozturk, Kasif Furkan; Cakir, Tufan; Araz, Onur
Geotechnical seismic isolation (GSI) systems aim to partially dissipate the energy before it reaches the foundation of the structure system and are therefore regarded as an important alternative to structural seismic isolation systems. In addition, the use of petroleum-derived waste materials in the GSI systems fills a significant gap in the field of waste recovery. The present study investigates the changes in the dynamic responses of a 5-story building system with and without GSI, using a set of earthquakes classified according to their frequency content. For this purpose, parametric analyses were performed using analytical methods, considering three different earthquake frequency contents and six different GSI thicknesses. Furthermore, an approach for selecting the GSI thickness was suggested. The results generally show that, for structures founded on both natural soil (NS) and GSI systems, the earthquakes with low frequency content produce responses greater than the average responses calculated for all the investigated earthquakes. Although increasing the GSI thickness has a significant effect on attenuating structural responses, increasing this thickness beyond 3 m does not lead to a relatively significant reduction in the dynamic responses of the investigated structural system. Therefore, considering the structural system, NS, rubber-soil mixtures and earthquakes examined in this study, selecting a GSI thickness in the range of 2–3 m (inclusive) may be regarded as a practical approach for mitigating the dynamic responses of the structure since further increments in thickness beyond this range provide only progressively limited improvements in structural responses. Consequently, this research may provide meaningful data for the development of vibration control strategies to improve seismic resilience of structures, and the results are expected to be useful for better understanding of the GSI applications.
- BildiriYalnız künye2026Dynamic Analysis of a High-Rise Building Under Near-Fault and Far-Fault Loads Considering Soil-Structure Interaction
Kaya, Dilek; Cakir, Tufan; Ozturk, Kasif Furkan; Ilki, A.; Goksu, C.; Cinar, T.; Erdik, M.
Earthquakes that have occurred in our country and various countries around the world over the past 30 years have clearly indicated that the complex relationship between the soil, structure, and earthquake requires further research. This situation has shown that building behavior under dynamic loads can vary depending on parameters such as structural geometry, foundation soil system characteristics, and earthquake characteristics. Due to the fact that near-fault movements contain higher accelerations and higher velocity components compared to far-fault movements, high-rise structures may exhibit relatively more sensitive behavior under such loads and may be negatively affected by these earthquake contents. In this context, the aim of this study is to investigate the dynamic behavior of a 12-story building system under near-fault and far-fault ground motions, taking into account different soil properties. To this end, three-dimensional finite element models were first created for the 12-story building system, considering both fixed and flexible foundation conditions. Modal analyses were performed using finite element models created with ANSYS software, and the obtained mode periods were compared with those obtained from analytical models. Subsequently, the dynamic behavior of the 12-story building system was investigated using relative displacement, stress, and acceleration responses obtained from time-domain analyses conducted for different soil systems and fixed foundation conditions. Comparisons of the dynamic responses showed that the structural dynamic responses could be influenced not only by the soil-structure interaction system but also by nearby and distant fault earthquakes.
- MakaleYalnız künye2025Assessment of Seismic Responses of Square-Hollow-Section Joints in a Lattice Girder with Soil-Structure Interaction
Ozturk, Kasif Furkan; Ozyurt, Emre; Araz, Onur; Cakir, Tufan
The fixed base approach is widely used to obtain the seismic behaviour of Square Hollow Section (SHS) joints in a lattice girder. However, in some cases where soil-structure interaction (SSI) can be relatively significant, this approach may result in incorrect acquisition of the natural periods and dynamic responses of the lattice girders using welded tubular joints. This situation may negatively affect the safety of the structure by causing an underestimation of the dynamic loads acting on the structure. Therefore, this study evaluates the seismic behaviour of SHS joints in a typical lattice girder exposed to different ground motions considering SSI. A nonlinear finite element analysis software, Abaqus, performs the dynamic analyses considering six earthquake excitations with three different frequency contents (a ratio of peak ground acceleration (PGA) to peak ground velocity (PGV)) and four different soil types. After verifying the numerical model, it is determined that 3D solid elements should be used to capture the actual seismic behaviour of the tubular joints in a steel truss frame with or without SSI. A comprehensive parametric study is then carried out to evaluate the peak displacement and stress values on the SHS joints with and without SSI under different ground motions with different PGA/PGV ratios. The findings show that the stresses are concentrated around the column and bottom chord connection region. Besides, the SSI mechanism significantly affects the peak stress and displacement values of the SHS joints, especially in soft soil types. Furthermore, it is observed that the PGA/PGV ratio significantly changes the seismic responses of the steel truss frame.
- MakaleYalnız künye2025Effect of frequency content of ground motion on seismic response of buildings with variable aspect ratio including soil-structure interaction
Kaya, Dilek; Cakir, Tufan; Ozturk, Kasif Furkan; Araz, Onur
Soil-structure interaction (SSI) may lead to reduction, amplification or negligible change in structural responses depending on the relationship between the nature of excitations and subsoil conditions. Since neglecting SSI effects may cause uncertainties in seismic design, it is crucial to consider them during the design process. Another important factor affecting the dynamic behavior of structures interacting with the ground is the dynamic properties of the structures. To consider this effect, three buildings with 4, 8, and 12 stories designed in accordance with the Turkish Building Earthquake Code (TBEC-2018) are analyzed. The aspect ratios of these structures are 2, 4, and 6, corresponding to squat, ordinary, and slender structures, respectively. The primary objective of this study is to simulate the combined effects of these key parameters on the dynamic response of reinforced concrete structures. In the time history analyses, six ground motions classified by three different frequency contents are considered. 3D finite element models of SSI systems are established using ANSYS software. The usability of the numerical models is demonstrated for both SSI and fixed-base cases through three different analytical approaches. The displacement, acceleration, and stress responses are examined through time history analyses. The results indicate that the SSI is not negligible and neglecting the SSI is an oversimplification that does not lead to always-conservative predictions. Moreover, both the frequency content of the excitation and the structural aspect ratio are found to be decisive parameters in seismic response.
- MakaleYalnız künye2023Effect of foundation embedment ratio in suppressing seismic-induced vibrations using optimum tuned mass damper
Araz, Onur; Cakir, Tufan; Ozturk, Kasif Furkan; Kaya, Dilek
Tuned mass damper (TMD), which is used in structures to mitigate the dynamic responses caused by environmental loads, is tuned according to the dominant frequency of the structures. The dominant frequency of structure built on soil with low stiffness is significantly affected by the soil-structure interaction (SSI). In previous studies, only the surface foundation case is considered to investigate the design parameters of TMD considering SSI effects and the embedment depth of the foundation is neglected in these studies. Thus, this paper investigates the optimization of TMD for mitigation of responses of a high-rise building considering various depths of embedment and soil properties. The optimum parameters of TMD are investigated using five different optimization algorithms (i.e., simulated annealing, sequential quadratic programming, genetic algorithm, pattern search, and particle swarm optimization). The objective function minimizes the peak acceleration amplitude at the top of the structure. The effectiveness of optimum TMD is verified to use 20 near-fault pulse-like ground motions. The comparisons show that the embedment ratio of the foundation and the soil properties significantly affect the optimization of TMD.
- MakaleYalnız künye2023Influences of Wall Configurations on Earthquake Behavior of Cantilever Retaining Walls Considering Soil-Structure Interaction Effects
Ozturk, Kasif Furkan; Cakir, Tufan; Araz, Onur
Cantilever walls are frequently and necessarily built not only in earthquake prone regions but also on different foundation subsoils with various physical and mechanical characteristics. The response of these structures is a complicated soil-structure interaction (SSI) problem, in which the relative stiffness between the soil and structure is of critical importance. In addition to different soil conditions and earthquake motions, the wall configurations have an important role in the cantilever retaining wall design. Thus, the major objective of this work is to investigate the effects of various configurations on seismic response of the cantilever retaining walls considering SSI. Accordingly, the seismic response of the interaction systems is revealed using the 3D finite element models (FEM) in time domain, assuming linearly elastic behavior for the wall, and elastoplastic behavior for backfill and foundation soil. Viscous absorbent boundaries are employed to both simulate radiation scenario and avoid undesirable wave reflections generated by soil lateral boundaries. Backfill-wall interfaces are modeled using the unidirectional interface elements with nonlinear force-deflection abilities. The interaction systems are analyzed considering three different cantilever wall configurations (inverted T-type, L-type, and the wall with a base key), four different ground motion records, and four different subsoil systems. Nonlinear seismic analyses are carried out to visit how considering the variation of these parameters influences the wall behavior. The results from parametric studies show that the wall configuration, SSI effects and ground motions are remarkably influential on seismic responses of the cantilever walls such as the stresses and horizontal displacements.
- MakaleYalnız künye2022Effect of earthquake frequency content on seismic-induced vibration control of structures equipped with tuned mass damper
Araz, Onur; Cakir, Tufan; Ozturk, Kasif Furkan
The main goal of this paper is to investigate the influence of the earthquake frequency content on the optimization of tuned mass damper (TMD) for multi-story buildings. Earthquake frequency content is divided into three groups (i.e., low, intermediate and high frequency content) according to the ratio of peak ground acceleration to the peak ground velocities. Time-domain analyses are performed to obtain the dynamic responses of 10-story and 40-story shear buildings equipped with a TMD under twelve different earthquake records. Advanced firefly algorithm is used to obtain the optimum parameters of the TMD such as the frequency ratio and the damping ratio. The optimization criterion is selected as the minimization of the maximum top story displacement of the building with TMD. The optimum parameters of TMD designed by this paper and its control performance are compared with those of other previous works available in the literature. Compared to the other methods, the optimum TMD designed by this study especially performs better in reducing the maximum top story displacements. Furthermore, it is discussed why TMD is ineffective in reducing the maximum floor accelerations of 40-story building, and then the effect of different mass ratios and objective functions in reducing the maximum responses of both buildings under critical earthquake excitation is investigated in detail. The results also show that the frequency content of earthquake ground motions has a significant effect on the optimum parameters of TMD and its control performance.
- MakaleYalnız künye2022A comparative study to determine seismic response of the box culvert wing wall under influence of soil-structure interaction considering different ground motions
Ozturk, Kasif Furkan; Cakir, Tufan; Araz, Onur
The present study deals with evaluation of the effects of different ground motions, backfill-structure interaction (BSI) and soil-structure interaction (SSI) on dynamic response of a box culvert wing wall. In obtaining numerical results, five different earthquake records with different frequency contents, five different backfill types and four different subsoil types are taken into account. Firstly, a finite element model (FEM) and three analytical models are proposed for analysis of the wing wall-backfill system under fixed-base case, and these fixed-base models are compared with each other through both modal analysis and displacement time-history analysis under the assumption of linear-elasticity. After validating the ability of the FEM approach, by extending the fixed-base FEM to take account of elastoplastic behavior of soil and SSI, a three dimensional (3-D) model has been described, and 3-D nonlinear analyses have been carried out in time domain. The numerical results show that the seismic response of the wing walls are affected remarkably by the SSI, BSI and frequency content of the earthquake.
- MakaleYalnız künye2022Effect of different objective functions on control performance of tuned mass damper for a high-rise building considering soil–structure interaction
Araz, Onur; Ozturk, Kasif Furkan; Cakir, Tufan
This paper deals with the optimization of the tuned mass damper (TMD) with different objective functions for high-rise building under earthquake motions considering soil–structure interaction (SSI). A study is conducted to search for the TMD that outperforms five objective functions (i.e., OF-1–OF-5) containing combinations of the structural responses and foundation responses. The main goal of the present study is to evaluate and compare the control performance of these five objective functions. The optimum parameters of TMD are obtained by particle swarm algorithm (PSA) to minimize the acceleration transfer function. To determine the dynamic response of a 40-story building under the influence of SSI, six different foundation soil conditions and eight different earthquake records are considered. The results show that the SSI effects on the dynamic response of the high-rise building resting on relatively soft soil types such as SD and SE are of critical importance. It is shown that the effectiveness of the optimum TMD designed by OF-1 is better than the others in suppressing the peak response values for all soil types. After OF-1, the best performances are obtained for OF-3 and OF-5 which yield approximately the same effectiveness. It is also found that different earthquake records, soil types and objective functions are very effective on the effectiveness of TMD.
- MakaleYalnız künye2020AN OVERVIEW TO THE DYNAMIC BEHAVIOUR OF THE INVERTED T TYPE CANTILEVER RETAINING WALL TAKING INTO ACCOUNT SOIL STRUCTURE INTERACTION PHENOMENON
Cakir, Tufan; Ozturk, Kasif Furkan
The dynamic response of the cantilever retaining walls is affected by many factors such as the geometry of the wall, the earthquake frequency content, the wall flexibility, the backfill characteristics, and the soil structure interaction. Therefore, it may not be possible to analyse all aspects of the dynamic response of the cantilever retaining walls in spite of their simplicity. It is also well known that some unfavourable effects on the behaviour of the walls may impair the balance of the wall. In this context, the study aims to investigate the dynamic response of the T type cantilever retaining wall considering soil structure interaction. In line with this purpose, the soil structure interaction system is produced with a three dimensional finite element model. The seismic analyses are performed in time domain using C-OLC360 component of 1983 Coalinga earthquake, and four different foundation soil systems are used in these analyses. The elasto-plastic behaviour of the backfill and the foundation soil are represented with Drucker-Prager material model. In order to reflect the material damping of the system, Rayleigh damping is utilized considering mass and stiffness proportional dampings. In addition, the viscous boundary dashpot elements which consider the criteria of Lysmer and Kuhlemeyer for wave propagation, are placed around the boundaries of the numerical model. The results are examined in terms of both the stresses and displacements. The findings have revealed that the dynamic response of the T shaped cantilever retaining walls is considerably affected by the soil structure interaction.
- MakaleYalnız künye2017Assessment of effect of material properties on seismic response of a cantilever wall
Cakir, Tufan
Cantilever retaining wall movements generally depend on the intensity and duration of ground motion, the response of the soil underlying the wall, the response of the backfill, the structural rigidity, and soil-structure interaction (SSI). This paper investigates the effect of material properties on seismic response of backfill-cantilever retaining wall-soil/foundation interaction system considering SSI. The material properties varied include the modulus of elasticity, Poisson’s ratio, and mass density of the wall material. A series of nonlinear time history analyses with variation of material properties of the cantilever retaining wall are carried out by using the suggested finite element model (FEM). The backfill and foundation soil are modelled as an elastoplastic medium obeying the Drucker-Prager yield criterion, and the backfill-wall interface behavior is taken into consideration by using interface elements between the wall and soil to allow for de-bonding. The viscous boundary model is used in three dimensions to consider radiational effect of the seismic waves through the soil medium. In the seismic analyses, North-South component of the ground motion recorded during August 17, 1999 Kocaeli Earthquake in Yarimca station is used. Dynamic equations of motions are solved by using Newmark’s direct step-by-step integration method. The response quantities incorporate the lateral displacements of the wall relative to the moving base and the stresses in the wall in all directions. The results show that while the modulus of elasticity has a considerable effect on seismic behavior of cantilever retaining wall, the Poisson’s ratio and mass density of the wall material have negligible effects on seismic response.
- BildiriAçık Erişim2015Finite Element Based Investigation of Backfill Effects on Seismic Behavior of a Cantilever Wall
Cakir, Tufan; Drusa, M; Marschalko, M; Yilmaz, I; Segallini, A; Ferrero, AM; Bednarik, M
A series of finite element analyses were conducted to investigate the backfill effects on seismic behavior of a cantilever retaining wall incorporating backfill and subsoil interactions. Considering four different backfill soil conditions, the dynamic analyses of backfill-cantilever wall-soil/foundation system were carried out in time domain through ANSYS general purpose finite element computer program. The cohesionless soil was modelled as an elasto-plastic medium with viscous boundary applied on the artificial boundary of soil to simulate the wave energy absorption. Backfill-cantilever wall interface behavior was taken into account by using interface elements between the wall and soil to allow for de-bonding. The magnitudes of lateral displacements and stresses were determined. The obtained results show that the earthquake behavior of cantilever retaining walls can change considerably due to the backfill interaction. Thus, the backfill interaction should be considered in design criteria of cantilever walls. (C) 2015 The Authors. Published by Elsevier B.V.
- MakaleYalnız künye2014Backfill and subsoil interaction effects on seismic behavior of a cantilever wall
Cakir, Tufan
The main focus of the current study is to evaluate the dynamic behavior of a cantilever retaining wall considering backfill and soil/foundation interaction effects. For this purpose, a three-dimensional finite element model (FEM) with viscous boundary is developed to investigate the seismic response of the cantilever wall. To demonstrate the validity of the FEM, analytical examinations are carried out by using modal analysis technique. The model verification is accomplished by comparing its predictions to results from analytical method with satisfactory agreement. The method is then employed to further investigate parametrically the effects of not only backfill but also soil/foundation interactions. By means of changing the soil properties, some comparisons are made on lateral displacements and stress responses. It is concluded that the lateral displacements and stresses in the wall are remarkably affected by backfill and subsoil interactions, and the dynamic behavior of the cantilever retaining wall is highly sensitive to mechanical properties of the soil material.
- MakaleYalnız künye2014Influence of wall flexibility on dynamic response of cantilever retaining walls
Cakir, Tufan
A seismic evaluation is made of the response to horizontal ground shaking of cantilever retaining walls using the finite element model in three dimensional space whose verification is provided analytically through the modal analysis technique in case of the assumptions of fixed base, complete bonding behavior at the wall-soil interface, and elastic behavior of soil. Thanks to the versatility of the finite element model, the retained medium is then idealized as a uniform, elastoplastic stratum of constant thickness and semi-infinite extent in the horizontal direction considering debonding behavior at the interface in order to perform comprehensive soil-structure interaction (SSI) analyses. The parameters varied include the flexibility of the wall, the properties of the soil medium, and the characteristics of the ground motion. Two different finite element models corresponding with flexible and rigid wall configurations are studied for six different soil types under the effects of two different ground motions. The response quantities examined incorporate the lateral displacements of the wall relative to the moving base and the stresses in the wall in all directions. The results show that the wall flexibility and soil properties have a major effect on seismic behavior of cantilever retaining walls and should be considered in design criteria of cantilever walls. Furthermore, the results of the numerical investigations are expected to be useful for the better understanding and the optimization of seismic design of this particular type of retaining structure.
- MakaleYalnız künye2013Evaluation of the effect of earthquake frequency content on seismic behavior of cantilever retaining wall including soil-structure interaction
Cakir, Tufan
A three-dimensional backfill-structure-soil/foundation interaction phenomenon is simulated using the finite element method in order to analyze the dynamic behavior of cantilever retaining wall subjected to different ground motions. Effects of both earthquake frequency content and soil-structure interaction are evaluated by using five different seismic motions and six different soil types. The study mainly consists of three parts. In the first part, following a brief review of the problem, the finite element model with viscous boundary is proposed under fixed-base condition. In the second part, analytical formulations are presented by using modal analysis technique to provide the finite element model verification, and reasonable agreement is found between numerical and analytical results. Finally, the method is extended to further investigate parametrically the effects of not only earthquake frequency content but also soil/foundation interaction, and nonlinear time history analyzes are carried out. By means of changing the soil properties, some comparisons are made on lateral displacements and stress responses under different ground motions. It is concluded that the dynamic response of the cantilever wall is highly sensitive to frequency characteristics of the earthquake record and soil-structure interaction.
- MakaleYalnız künye2013Experimental analysis on FEM definition of backfill-rectangular tank-fluid system
Cakir, Tufan; Livaoglu, Ramazan
In the present study, the numerical and experimental investigations were performed on the backfill- exterior wall-fluid interaction systems in case of empty and full tanks. For this, firstly, the non-linear three dimensional (3D) finite element models were developed considering both backfill-wall and fluid-wall interactions, and modal analyses for these systems were carried out in order to acquire modal frequencies and mode shapes by means of ANSYS finite element structural analysis program. Secondly, a series of field tests were fulfilled to define their modal characteristics and to compare the results from proposed approximation in the selected structures. Finally, comparing the theoretical predictions from the finite element models to results from experimental measurements, a close agreement was found between theory and experiment. Thus, it can be easily stated that experimental verifications provide strong support for the finite element models and the proposed procedures themselves are the meritorious approximations to the real problem, and this makes the models appealing for use in further investigations.
- MakaleYalnız künye2012Fast practical analytical model for analysis of backfill-rectangular tank-fluid interaction systems
Cakir, Tufan; Livaoglu, Ramazan
The paper describes a simple, efficient and reasonably accurate analytical model for analysis of backfill-rectangular tank-fluid interaction systems. The presented model uses Housner's two-mass approximation for fluid interaction and mass-spring-dashpot system for backfill interaction and accommodates a variety of features that may affect the behavior of rectangular tanks including fluid volume, backfill geometry, soil properties and flexible/rigid wall types. Unlike the conventional finite element and the finite difference models that require considerable effort and knowledge to prepare the input data, the proposed model requires only a few pieces of data to define the problem and control the analysis. A series of finite element simulations were also fulfilled on two real rectangular tanks subjected to backfill and fluid effects. A reasonably good accord was obtained comparing the analytical predictions to results from numerical simulations. Thus, it can be stated that the model may be used effectively to perform a broad suite of parametric studies at the design stage and also as a reliable tool for estimating the system behavior. The results obtained from parametric seismic analyses indicated that backfill interaction, wall flexibility and fluid interaction considerably affect the lateral displacements. The sloshing response, however, was not practically affected by the backfill interaction and the wall flexibility.
- MakaleYalnız künye2011Effects of backfill on seismic behavior of rectangular tanks
Livaoglu, Ramazan; Cakir, Tufan; Dogangun, Adem; Aytekin, Mustafa
The reliability and/or stability of the lifeline structures against failure under seismic loads are of critical concern, and must be studied carefully. Therefore, the main objective of this paper is to demonstrate the commonly encountered backfill effects on the dynamic response of rectangular tanks. However, only the exterior wall of the tank which interacts with both the backfill and fluid is tackled, as each part of the structure shows considerable differences in terms of both the load bearing mechanisms and the geometrical and positional differences. Finite element analyses are employed, taking into consideration the fluid-wall-backfill interaction. The analyses are conducted to observe whether or not both backfill and wall behavior can be affected by variation of the internal friction angle. For that purpose, some comparisons are made on vertical displacements of the backfill, roof displacements, stress responses, etc., by means of internal friction angle variations of the backfill from 25 degrees to 40 degrees. Consequently, it is observed that the variations on maximum vertical displacements are affected considerably. In contrast, the maximum stress responses are affected partially. However, the inertial effects of the backfill show that pseudo-static approximations may be insufficient to understand the dynamic behavior of the backfill-wall-fluid system. (C) 2011 Elsevier Ltd. All rights reserved.