Papers by Cuneyt Vatansever
Nonlinear Behavior of Bolted Extended End-Plate Beam to Column Connections Subject to Cyclic Loading
Lecture notes in civil engineering, 2023
Experimental investigation of link beams with perforated web section in eccentrically braced frames
Advances in Structural Engineering, Jan 17, 2022
<jats:p> Eccentrically braced frame (EBF) system is one of the most effective lateral loads... more <jats:p> Eccentrically braced frame (EBF) system is one of the most effective lateral loads resisting systems for steel structures. In these systems, links are designed in such a way that they yield in shear not only to provide high ductility and rigidity but also to provide a high energy dissipation capacity. In particular, as the internal forces to be considered for the design of the members outside of the links must be calculated with the amplification factor based on the yielding of the links, the magnitude of the internal forces may become so large that they may not be met by the adjacent members. Therefore, it is challenging to develop an economic design for adjacent members and connections because of the high level of design loads obtained by the amplification factor. This paper studies the effect of the perforation arrangement in the web of shear link beams in eccentrically braced frames. Both experimental and numerical investigation were conducted to demonstrate the effectiveness of the link beam with slotted perforations in the web portion. Seven equivalent isolated link beam specimens with various slot-hole patterns were tested under quasi-static cyclic loading. The results of the study indicate that using slot-holes in the web portion reduces the link shear capacity significantly. The results also show that the failure mechanism of reduced link sections was controlled by fracture at end of the slot-holes and inelastic rotation capacities were varying between 0.025 rad and 0.065 rad depending on the slot-hole patterns. </jats:p>
Journal of The Faculty of Engineering and Architecture of Gazi University, Oct 7, 2022
Strain hardening factor for short, intermediate and long links Finite element model of link b... more Strain hardening factor for short, intermediate and long links Finite element model of link beams Finite element analyses under quasi-static cyclic loading In steel eccentrically braced frames (EBF), plastic deformations are confined to link beams under strong earthquake ground motions and seismic energy is dissipated through yielding of link beams. For an EBF, the capacity design principle requires that connections, columns, braces, and beam segments outside of the link be designed to remain essentially elastic while the link beams fully yield and strain harden during the design earthquake. For the design of all structural components other than link beams, the required strengths must be obtained with the combination of the factored gravity forces plus the forces produced by the adjusted shear strength of the link that contains the effect of strain hardening, using the load combinations including the overstrength seismic load. Strain hardening factors which are considered to obtain overstrength factor are specified in TBSC (Turkey Building Seismic Code) 2018 for the structural components outside of the link. Analysis results given in the Figure A indicate that the strain hardening factor of 1.25 which are specified in TBSC 2018 is unconservative for link beams.
Yarı-rijit kiriş-kolon birleşimli ince levhalı bir çelik perdenin tersinir yükler altında davranışı
İTÜDERGİSİ/d, Sep 5, 2011
... perdenin tersinir yükler altında davranışı Cüneyt VATANSEVER*, Nesrin YARDIMCI İTÜ Fen Biliml... more ... perdenin tersinir yükler altında davranışı Cüneyt VATANSEVER*, Nesrin YARDIMCI İTÜ Fen Bilimleri Enstitüsü, Yapı Mühendisliği Programı, 34469, Ayazağa, İstanbul Page 2. ... Hesaplarda ikinci derece polinom eğrisinin gözönüne alındığı regresyon analizinden yarar-lanılmıştır. ...
Pamukkale University Journal of Engineering Sciences, 2020
The aim of this paper is to investigate the nonlinear behavior of space truss roofs subject to di... more The aim of this paper is to investigate the nonlinear behavior of space truss roofs subject to different load accumulation forms considering the effect of initial imperfection and slenderness ratio of the truss members. For this, a typical space truss roof using MERO-connection type with flat double-layer was selected as a sample. 3D model of the roof was developed and analyzed by using OpenSEES. Nonlinear behavior of each typical bar of the space truss roof, which, was mainly composed of particular sub-elements such as a tubular element, bolts, sleeves and spheres was represented by a single truss bar. Axial load-displacement relationship of each single truss bar was obtained from nonlinear analysis performed under reversal cyclic loading. Besides, three different types of load distribution that simulates accumulation of rainwater or drifted snow were taken into account as an external load acting on upper layer of the roof system. Analyses results showed that load carrying capacity of the space truss roofs was susceptible to the form of accumulation and reduces abnormally when the accumulation, in particular, occurred locally. Furthermore, failure mode of the system designed with optimal solution was dominated by buckled truss bars and brittle failure occurred. Also initial imperfection had a negative effect on the members in compression. Bu çalışmada uzay kafes çatı sistemlerinin çeşitli yük birikme senaryoları altındaki doğrusal olmayan davranışı, çubuk eleman başlangıç kusurları ve çubuk eleman narinlikleri de dikkate alınarak incelenmiştir. MERO düğüm noktasına sahip iki adet örnek uzay kafes çatı sistemi OpenSEES yazılımı üç boyutlu olarak modellenerek analizler gerçekleştirilmiştir. Bulonlar, somunlar ve düğüm noktası kürelerinden oluşan her bir çubuk elemanın davranışı tekil çubuklar üzerinde tanımlanarak genel sisteme aktarılmıştır. Her bir çubuk elemanın eksenel yük-yerdeğiştirme davranışları çevrimsel tekrarlı yükler altında analizler gerçekleştirilerek elde edilmiştir. Genel sistem analizleri çatının tamamında, yarısında ve dörtte birinde yağmur suyu veya kar yükü yığılmalarını yansıtacak şekilde belirlenen yükleme altında gerçekleştirilmiştir. Analizler sonucunda uzay kafes çatı sistemlerinin yük yığılmalarına karşı hassas oldukları ve lokal bölgelerde oluşan yük yığılmalarının sistemin taşıma kapasitesini düşürdüğü görülmüştür. Bunun yanında, en ekonomik kesitlerle boyutlandırılan sistemde göçme basınç çubuklarının burkulması ile gevrek bir şekilde meydana gelmiştir. Ayrıca, çalışma kapsamında başlangıç kusurlarının çubuk elemanların basınç kapasitelerini düşürdüğü görülmüştür.
Teknik Dergi, Jul 1, 2022
This paper presents the influence of gravity framing on the collapse risk of steel frame building... more This paper presents the influence of gravity framing on the collapse risk of steel frame buildings with perimeter special moment frames (SMFs) designed in Turkey. For this, fourand eight-story buildings have been designed considering the related current specifications and codes. Header end-plate connections are used for the beam-to-column joints of the gravity frame system. A nonlinear analytical model that simulates the hysteretic behavior of header end-plate connections is calibrated with past experimental data. Nonlinear static pushover analysis (NSPA) and nonlinear response history analyses (NRHAs) were implemented for both four-story and eight-story SMFs with and without the gravity framing to quantify their collapse performance and monitor the system-level seismic response of the building through collapse. The advantage of presence of the gravity framing is investigated and differences in structural responses between the models are also examined. When the models were excited by different ground motions, median responses of the detailed models showed an increase in lateral force carrying capacity and a decrease in first-story drift demand, compared to the nonlinear static pushover analyses results. Furthermore, the results demonstrate that gravity frames in a structure profoundly decrease the possibility of collapse.
Engineering Failure Analysis, Dec 1, 2019
Some bars of space truss roof a major shopping market chain in Adana, Turkey have experienced fle... more Some bars of space truss roof a major shopping market chain in Adana, Turkey have experienced flexural buckling without any circumstance of overloading induced by snow and rain together with wind that has led to the buckling phenomenon. However, according to the on-site geotechnical surveys that have demonstrated that an increase in consolidation settlement of foundation soil has occurred, it has been realized that differential support settlements may cause the truss bars to buckle. This paper investigates the probable cause of the buckling phenomenon observed in some truss bars based on the soil condition. For this, a photogrammetric survey has initially been performed to determine the existing vertical position of the roof supports located on the top of the cantilever columns. To obtain the amount of settlements of the supports, initial vertical coordinates of the tips of the columns that were determined before assembling of the roof are subtracted from those obtained by the photogrammetric measurement with respect to the reference point. An observation has also been made in site to visually inspect the distribution pattern of the buckled truss bars. A 3D analytical model of the roof has been developed to understand whether or not the buckling failure of the truss bars is resulted from the soil settlement under the individual foundations. When the observed distribution pattern of the buckled truss bars is compared to that obtained by the nonlinear analysis, a reasonably good agreement has been achieved, which shows that the truss bars have buckled because of the effects caused by differential settlements among the individual foundations due to increase in consolidation settlement occurred within the soil that surrounds the structure.
Analytical investigation of thin steel plate shear walls with screwed infill plate
Steel and Composite Structures, Nov 25, 2015
A behavior model for screw connections is developed to provide a better representation of the non... more A behavior model for screw connections is developed to provide a better representation of the nonlinear response of thin steel plate shear walls (TSPSWs) with infill plates attached to the boundary frame members via self-drilling screws. This analytical representation is based on the load-bearing deformation relationship between the infill plate and the screw threads. The model can be easily implemented in strip models of TSPSWs where the tension field action of the infill plates is represented by a series of parallel discrete tension-only strips. Previously reported experimental results from tests of two different TSPSWs are used to provide experimental validation of the modeling approach. The beam-to-column connection behavior was also included in the analyses using a four parameter rotational spring model that was calibrated to a test of an identical frame as used for the TSPSW specimens but without the infill plates. The complete TSPSW models consisting of strips representing the infill plates, zero length elements representing the load-bearing deformation response of the screw connection at each end of the strips and the four parameter spring model at each beam-to-column connection are shown to have good agreement with the experimental results. The resulting models should enable design and analysis of TSPSWs for both new construction and retrofit of existing buildings.
Cyclic behavior and numerical modelling of a semi-rigid frame
Steel Construction, Sep 1, 2010
It is clear that semi‐rigid frames exhibit completely non‐linear behaviour under cyclic loading d... more It is clear that semi‐rigid frames exhibit completely non‐linear behaviour under cyclic loading due to gradual yielding of connection components. The current study presents the experimental results from the test of a semi‐rigid frame specimen, comprising a single storey and one bay, and the analysis results obtained from a finite element model of the specimen. In this study, semi‐rigid joints with header plates are used for beam‐tocolumn connections. The initial stiffness and moment‐carrying capacity of the connection, designed as a semi‐rigid and partial strength connection type, were determined in accordance with Eurocode 3. In the modelling of the semi‐rigid beam‐to‐column connection behaviour, four‐parameter non‐linear representation of the moment—rotation curve obtained using the Ramberg‐Osgood formula was employed. Loading of the test specimen consisted of quasi‐static cycles with displacement control. The cyclic response of the specimen is characterized by a stable hysteretic behaviour. When comparing the envelope of the hysteresis loops from the cyclic test of the specimen with the pushover curve achieved by non‐linear finite element analysis, the model gives a good prediction of the ultimate strength and initial stiffness of the frame.
Experimental investigation of thin steel plate shear walls with different infill-to-boundary frame connections
Steel and Composite Structures, May 25, 2011
ABSTRACT To make direct comparisons regarding the cyclic behavior of thin steel plate shear walls... more ABSTRACT To make direct comparisons regarding the cyclic behavior of thin steel plate shear walls (TSPSWs) with different infill-to-boundary frame connections, two TSPSWs were tested under quasi-static conditions, one having the infill plate attached to the boundary frame members on all edges and the other having the infill plate connected only to the beams. Also, the bare frame that was used in the TSPSW specimens was tested to provide data for the calibration of numerical models. The connection of infill plates to surrounding frames was achieved through the use of self-drilling screws to fish plates that were welded to the frame members. The behavior of TSPSW specimens are compared and discussed with emphasis on the characteristics important in seismic response, including the initial stiffness, ultimate strength and deformation modes observed during the tests. It is shown that TSPSW specimens achieve significant ductility and energy dissipation while the ultimate failure mode resulted from infill plate fracture at the net section of the infill plate-to-boundary frame connection after substantial infill plate yielding. Experimental results are compared to monotonic pushover predictions from computer analysis using strip models and the models are found to be capable of approximating the monotonic behavior of the TSPSW specimens.
Challenge journal of structural mechanics, Sep 4, 2018
In seismically active regions such as Turkey, the context of the nonlinearity provided by a build... more In seismically active regions such as Turkey, the context of the nonlinearity provided by a building is based on the behaviors of structural components; beams, columns and their connections constituting the seismic force resisting system of the structure. Of these members, beam-to-column connections can play a considerably important role even if they have a capability of limited stiffness and flexural strength. Structural steel connections are mainly classified as a pinned or a moment connection. However, some beam-to-column connections having limited stiffness and flexural strength, which are called semi-rigid connections such as header end-plate connections designed so as to transmit only shear forces, can be characterized by moment-rotation relationship. This paper investigates the behavior of header end-plate connections using finite element (FE) modeling. The FE models include material, geometrical and contact nonlinearities. FE modeling technique was first verified through the test results of the experimental research performed by Aggarwal (1990). Then the effect of header end-plate thickness upon moment-rotation relationship was investigated. According to the analyses results, in addition to shear stresses, axial tensile stresses have been observed to occur in the bolts at the tension side and thickness of the header end-plate and beam web play a governing role in the development of initial rotational stiffness and the flexural strength of header end-plate connections.
Experimental and Numerical Investigation of Unreinforced Masonry Walls with and without Opening
International Journal of Architectural Heritage, Jun 14, 2022
Engineering Failure Analysis, Sep 1, 2017
This paper addresses the snow induced collapse of hail protection canopies of a major car dealers... more This paper addresses the snow induced collapse of hail protection canopies of a major car dealership in Istanbul, Turkey. Each of them with different plan dimensions has been built to provide an enclosed space of over 50,000 square meters for parking. The structural system of each hail protection canopy consists of successive steel frames spaced at 5.0 m intervals. Some of these canopies collapsed on January 1st, 2016. The rest has been saved thanks to the immediate intervention provided by the employees allowing accumulated snow to slide off the roof. Following the incident, a site investigation has been conducted to inspect the structural failures and a numerical 3D model to represent the whole structure was developed using OpenSEES to understand the collapse mechanism of the hail protection canopies. In addition, the scope of the structural design calculations was examined to check for potential incorrect design assumptions. Consequently, site observations and analysis results indicate that the hail protection canopies collapsed due to a combination of erroneous design assumptions on snow load and the poor design and construction of structural members and their connections.
Gövdesi Boşluklu Bağ Kirişleri Üzerine Bir Araştırma
Uluslararası Teknolojik Bilimler Dergisi, May 31, 2019
The context of the nonlinearity provided by a building is based on the behaviors of structural co... more The context of the nonlinearity provided by a building is based on the behaviors of structural components; beams, columns and their connections constituting the seismic force resisting system of the structure. Of these members, beam-to-column connections can play a considerably important role even if they have a capability of limited stiffness and flexural strength. Structural steel connections are mainly classified as a pinned or a moment connection. However, some beam-to-column connections having limited stiffness and flexural strength, which are called semi-rigid connections such as header end-plate connections can be characterized by moment-rotation relationship. For this characterization, the effect of some parameters such as thickness of the header end-plate, depth of the connection and number of the bolt rows on the behavior of header end-plate connections has been investigated by the help of finite element (FE) models. These models include material, geometrical and contact nonlinearities. Each material for each member is defined by true stress-true strain curve. According to the analyses results, in addition to shear stresses, axial tensile stresses have been observed to occur in the bolts at the tension side. Thickness of the header end-plate, depth of the connection and beam web play a governing role in the development of initial rotational stiffness and the flexural strength of the header end-plate connections. However, for the equal connection depth, increasing the number of bolt rows has not influenced the connection behavior remarkably. An additional study has also been conducted on yield line analysis to identify the behaviors of header endplates. Analyses results have shown that header end-plate connections have limited stiffness and flexural strength. However, they seem to be promising to provide the structural systems with additional stiffness, ductility and strength.
Uluslararası Teknolojik Bilimler Dergisi, May 31, 2019
In eccentirally-braced frames (EBFs), link-to-column connections and the structural elements outs... more In eccentirally-braced frames (EBFs), link-to-column connections and the structural elements outside of the links must resist the internal forces generated by fully yielded and strain-hardened links. Using slotted perforated web section concept in shear link may help to prevent difficulty in design of link-tocolumn connections and all other frame members by limiting the link capacity without loss of its stability. For this, a shear link beam with a section of W10×33 was selected and three different slot hole pattern were generated in its web to form three different specimens. Finite element models of these specimens were developed using ABAQUS software. Material of link beam was ASTM A992 steel. A series of analyses were performed under quasi-static cyclic loading to study the behavior of link beam with reduced web section. 10.6% of area reduction in the web section with different hole arrangements were investigated and the effect of slotted perforated web on shear links was examined. Finite element analyses have revealed that equally spaced 6×4mm slots in the web had stable hysteresis behavior whereas strength degredation was occured when equally spaced 3×8mm slots were used in the web. The results of this study indicate that using high number of slot holes may help to limit forces transmitting to the link-to-column connections and all other frame members.
Seismic Performance of Multistory Chevron‐braced Steel Structures with Yielding Beams
ce/papers
Lateral loads are resisted by braces in concentrically braced frames. Therefore, braces meet the ... more Lateral loads are resisted by braces in concentrically braced frames. Therefore, braces meet the demand for the load combination based on the seismic provisions. The rest of the system including the connections are determined according to the capacity‐based design, where the brace members yield under tension and buckle under compression. Chevron or inverted V‐braced frames are generally preferred because they allow large openings for doors and windows. However, the seismic‐design requirements in current building codes lead to deep, heavy chevron beams to resist the unbalanced load at beam members due to pre‐ and post‐buckling compressive strength deterioration and full tensile yielding of the braces. This results in uneconomical design. Recent large‐scale experiments of chevron‐braced frames have demonstrated that limited beam yielding is not detrimental to chevron‐braced frame behavior and on the contrary, it utilizes a second yielding mechanism and thereby increases the story drif...
Pamukkale Üniversitesi Mühendislik Bilimleri Dergisi, Jun 9, 2021
Bu çalışma, taşıyıcı sistemini beton dolgulu kompozit kolonlar ile çelik kirişler içeren süneklik... more Bu çalışma, taşıyıcı sistemini beton dolgulu kompozit kolonlar ile çelik kirişler içeren süneklik düzeyi yüksek moment aktaran çerçevelerin oluşturduğu çok katlı bir binanın,
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Papers by Cuneyt Vatansever