Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Ozturk, Kasif Furkan(2)
- Ozyurt, E.(2)
- Adanur, S.(1)
- Adanur, Suleyman(1)
- Akköse, Mehmet(1)
- Altunisik, A.C.(1)
- Altunisik, Ahmet Can(1)
- Altunişik, Ahmet Can(1)
- Bayraktar, Alemdar(1)
- Cakir, Tufan(1)
- Genç, Ali Fuat(1)
- Gunaydin, M.(1)
- Günaydin, Murat(1)
- Karahasan, Olguhan Şevket(1)
- Livaoglu, Ramazan(1)
- Okur, Fatih Yesevi(1)
- Sevim, B.(1)
- Sevim, Baris(1)
- Wang, Y.C.(1)
Yayınlar
- MakaleAçık Erişim2025Scopus SJRQ1Investigation of the effects of mainshock-aftershock sequences on the dynamic responses of pipeline considering soil-pipeline interaction
Ozturk, Kasif Furkan
Pipelines are important structural elements that are frequently used today to meet many infrastructures needs such as drainage, natural gas or water transmission. In this context, the usability of such structures, which are important elements of infrastructure systems, especially after disasters such as earthquakes, is of great importance. For this reason, within the scope of this study, a parametric investigation of the seismic behaviors of a natural gas pipeline system under mainshock-aftershock sequences have been carried out, specifically taking into account the soil-natural gas pipeline interaction (SNGPI) in the help of finite element model (FEM) proposed. Before developing the model of SNGPI system proposed using solid element, the fundamental mode frequencies of the pipeline system modeled using the solid element for the verification have been compared with those of obtained from the pipeline system modeled using the beam element and the analytical solutions. After verification of proposed model is demonstrated, SNGPI system has been modeled and its fundamental modes have been compared with mode frequencies of soil stratum obtained from well-known simple analytic solutions. After this stage, the dynamic analyses of natural gas pipeline (NGP) system in the time domain have been carried out using four different soil systems and four different mainshock-aftershock sequences. The results of the nonlinear time-history analyses have been investigated in terms of the stress and the displacement responses. Parametric evaluations show that the greatest displacements and the stresses occurring at the considered nodes of NGP system may be importantly affected from mainshock-aftershock sequences and soil stiffness changes. As the soil stiffness decreases, both the peak stresses and displacements increased significantly. On the other hand, the same responses obtained under mainshock loadings, which have relatively lower peak ground acceleration (PGA)/peak ground velocity (PGV) ratio compared to aftershock loadings, are generally larger than those obtained under aftershock loadings.
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İncele - MakaleYalnız künye2025Scopus SJRQ1Influences of chord pre-stress on CHS X-joints with high-strength-steel at various temperatures
Ozyurt, E.; Wang, Y.C.
This study examines the influence of chord pre-stress on the behaviour and load resistance of Circular Hollow Section (CHS) X-joints with High Strength Steel (HSS) at various temperatures. This investigation uses a total number of seven hundred and four Finite Element simulation results to evaluate the level of accuracy of current Eurocode and CIDECT design guidelines in predicting the high-temperature resistance of these joints. The numerical simulations investigate the effects of changing brace-to-chord diameter (β), chord semi-diameter-to-thickness (γ), and brace-to-chord thickness (τ) ratios, as well as different prestressing levels (np) and temperatures (θ). The γ and τ ratios have a limited effect on the normalised joint strength, but the β ratio, and the prestressing level are highly influential. At ambient temperature, the CIDECT design approach is a more suitable method for calculating the chord pre-stress reduction factors for S355 joints. For HSS X-joints, the constant modification coefficient of 0.80 is inadequate, and this paper has proposed a new modification coefficient as a function of the pre-stress level. At elevated temperatures, the ambient temperature resistance of CHS X-joints can be modified by the reduction factor of the Young's modulus for S355 steel and that of the yield stress for S960 steel.
AtıfScopus3WoS3OpenAlex2İncele - MakaleYalnız künye2024Scopus SJRQ1Investigation of dynamic responses of three-sided underpass culvert under near-fault and far-fault ground motions considering soil-structure interaction
Ozturk, Kasif Furkan
Three-sided underpass culverts are structural systems used to provide passing vehicle or pedestrian. It is of great importance that such infrastructure systems remain useable, especially after disasters such as earthquakes that can cause great destruction, in order to ensure that infrastructure services can be maintained continuously. In this context, the aim of this study is to investigate using finite element method (FEM) the dynamic responses of three-sided underpass culvert system under near-fault ground motions with velocity pulse and far-fault ground motions. For this aim, the modal analysis of the soil-underpass culvert interaction system has been realized using proposed soil-structure interaction (SSI) model. The frequencies of the interaction system obtained from the finite element model developed using proposed approaches have been verified comparing with the results obtained from the literature and the site periods. After showing that the modes of the interaction system can be obtained with the help of the proposed numerical model, the full transient dynamic analyses have been performed in the time history using five near-fault and far-fault records, considering four different soil systems. The comparisons shows that the variations of the soil systems and the ground motion type can significantly affect the top peak relative displacements and the dynamic stresses of the three-sided underpass culvert.
AtıfScopus16WoS13OpenAlex15İncele - MakaleYalnız künye2020Scopus SJRQ1Finite element study on axially loaded reinforced Square Hollow Section T-joints at elevated temperatures
Ozyurt, E.
This study numerically investigates the elevated temperature resistance of collar plate and doubler plate reinforced Square Hollow Section (SHS) T-joints subjected to brace axial compressive load. The extensive numerical simulations were performed to examine the effects of the geometrical parameters of main members and reinforcing plate on the fire resistance of reinforced SHS T-joints after verification of the numerical models based on the available test results. The corresponding unreinforced joints were also analysed as reference resistance at five different temperature levels (20 °C, 400 °C, 500 °C, 600 °C, and 700 °C). Results indicate that the elevated temperature capacity of SHS T-joints can be significantly increased by using a collar plate or a doubler plate. Although the initial stiffness of the doubler plate reinforced joints was higher than the collar plate reinforced joints, their capacity was similar to each other. Also, the fire resistance of the reinforced joints mainly depended on the brace-to-chord width ratio and reinforcing plate thickness to chord wall thickness ratio. However, there was no beneficial effect on the fire resistance of reinforced joints when the thickness of the reinforcing plate was greater than 1.5 times the chord wall thickness. Moreover, there was an insignificant effect of half-width to thickness ratio of the chord, reinforcing length and reinforcing type as long as the required limit values of the reinforcing length and width were used based on the Eurocode 3 EN 1993-1-8. It is worth mentioning that modifying the steel yield strength in the ambient temperature design method to calculate the capacity of the reinforced SHS T-joints at elevated temperatures may be unsafe. A new design method was developed to predict the capacity of a collar plate and doubler plate reinforced SHS T-joints subjected to brace compressive load in fire.
AtıfScopus14WoS13OpenAlex14İncele - MakaleYalnız künye2018Scopus SJRQ1Dynamic response of a historical armory building using the finite element model validated by the ambient vibration test
Altunişik, Ahmet Can; Genç, Ali Fuat; Günaydin, Murat; Okur, Fatih Yesevi; Karahasan, Olguhan Şevket
In this paper, the aim was to determine the nonlinear dynamic response of historical masonry armory buildings using a validated finite element model. Eight ambient vibration tests were conducted on the building, using three different measurement test setups to extract the dynamic characteristics using the Enhanced Frequency Domain Decomposition method. A finite element model was constructed in ANSYS and the dynamic characteristics were obtained numerically. It can be seen that there is a good correlation between the mode shapes, but there are differences in natural frequencies with maximum values of 10.1%, 7.4% and 13.4% for first the three modes. To determine the nonlinear dynamic response, the validated finite element model was analyzed using the Kocaeli earthquake motion. The Drucker–Prager criterion and Willam–Warnke surface were considered for the nonlinear material models. At the end of the analyses, maximum displacements, principal stresses and strains are given in detail using contour diagrams. It is evident that the displacements show an increasing trend from the base to the top point of the building. Stresses occurred on the corners, openings and transition segments. In addition, crack distribution diagrams were drawn up to illustrate the stress accumulation points.
AtıfScopus26WoS25OpenAlex23İncele - MakaleAçık Erişim2015Scopus SJRQ2Static and dynamic responses of Halgavor footbridge using steel and FRP materials
Gunaydin, M.; Adanur, S.; Altunisik, A.C.; Sevim, B.
In recent years, the use of fiber reinforced polymer composites has increased because of their unique features. They have been used widely in the aircraft and space industries, medical and sporting goods and automotive industries. Thanks to their beneficial and various advantages over traditional materials such as high strength, high rigidity, low weight, corrosion resistance, low maintenance cost, aesthetic appearance and easy demountable or moveable construction. In this paper, it is aimed to determine and compare the geometrically nonlinear static and dynamic analysis results of footbridges using steel and glass fiber reinforced polymer composite (GFRP) materials. For this purpose, Halgavor suspension footbridge is selected as numerical examples. The analyses are performed using three identical footbridges, first constructed from steel, second built only with GFRP material and third made of steel-GFRP material, under static and dynamic loadings using finite element method. In the finite element modeling and analyses, SAP2000 program is used. Geometric nonlinearities are taken into consideration in the analysis using P-Delta criterion. The numerical results have indicated that the responses of the three bridges are different and that the response values obtained for the GFRP composite bridge are quite less compared to the steel bridge. It is understood that GFRP material is more useful than the steel for the footbridges.
AtıfScopus12WoS12OpenAlex9İncele - MakaleYalnız künye2013Scopus SJRQ2Experimental 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.
AtıfScopus8WoS9OpenAlex7İncele - MakaleYalnız künye2012Scopus SJRQ1Estimation of Elasticity Modulus of a Prototype Arch Dam Using Experimental Methods
Sevim, Baris; Altunisik, Ahmet Can; Bayraktar, Alemdar; Akköse, Mehmet; Adanur, Suleyman
Using experimental methods, this study presents the estimation of the dynamic and static ( secant) elasticity modules of a prototype arch dam. These experimental methods are ambient vibration tests, uniaxial compression tests, and ultrasonic velocity tests. Implementation of the methods on a prototypical arch dam-reservoir-foundation model of the dam, constructed under laboratory conditions, allows estimation of the elasticity modules. Random impact loads excite the arch dam during ambient vibration testing, which creates response signals for measurement. Commercially available software transfers the signals, and processing those signals allows estimation of the experimental natural frequencies of the arch dam. Analysis of a three-dimensional (3D) finite element model (FEM) of the arch dam determines natural frequencies. The estimation of the elasticity modules of the arch dam arises from a comparison of the experimental and analytical frequencies. The uniaxial compression tests use several specimens of the fresh and hardened concrete of the prototype model, and those tests provide the compressive strengths and stress-strain relationships. The ultrasonic velocity tests apply several velocity measurements to the arch dam and foundation, resulting in estimation of the elasticity modulus from empirical equations related to concrete mix design, compressive strength, and velocity values. This study discusses the difficulties of the determination of the elasticity modulus and suggests that ambient vibration testing and the finite element method are useful for overcoming these difficulties. DOI: 10.1061/(ASCE)MT.1943-5533.0000361. (C) 2012 American Society of Civil Engineers.
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