Taşıyıcı sistemi beton dolgulu kompozit kolonlar içeren dışmerkez çaprazlı çerçevelerden oluşan bir binanın tasarımı ve doğrusal olmayan analizi
Design and nonlinear analysis of a building with eccentrically braced frames having steel-concrete composite columns
Yazar: OĞUZCAN HADİM
Danışman: DR. ÖĞR. ÜYESİ CÜNEYT VATANSEVER
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / İnşaat Mühendisliği Ana Bilim Dalı / Yapı Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2018
Konu: İnşaat Mühendisliği = Civil Engineering

Özet:
Deprem bölgelerinde yapılacak yüksek binalarda güçlü yatay yük taşıyıcı sistemlerin kullanılmasına ihtiyaç duyulmaktadır. Yatay yük taşıyıcı sistemlerdeki en önemli yapı elemanlarından birİ kolonlardır. Yapı yüksekliği arttıkça daha güçlü, dolayısıyla planda daha büyük alan kaplayan kolonlara ihtiyaç duyulmaktadır. Deprem bölgelerinde yapılacak olan binalarda kompozit kolonlar ile güvenli ve estetik bir yatay yük taşıyıcı sistem oluşturulabilir. Bu çalışmada, yatay yük taşıyıcı sistemi, kompozit kolonlar içeren süneklik düzeyi yüksek dışmerkez çaprazlı çerçevelerden oluşan bir binanın tasarımını ve deprem etkileri altında doğrusal olmayan davranışının araştırılmasını kapsamaktadır.
Kompozit kolonlar, beton dolgulu kompozit kolonlar ve çelik gömme kompozit kolonlar olarak iki sınıfa ayrılır. Beton dolgulu kompozit kolonlar, yapısal çelik malzemesinden imal edilmiş kutu ya da boru profillerin içine beton doldurularak elde edilen kompozit kolonlardır. Çelik gömme kompozit kolonlar ise yapısal çelik malzemesinden imal edilmiş I veya H profillerin yüksek dayanımlı betonla çevrelenmesi ile oluşur. Kompozit kolonların enkesitlerinin davranışı, esas itibariyle, betonarme kolonlarınkine benzerdir. Ancak betonarme kolonlara göre daha narin olarak boyutlandırılmaları nedeniyle, tasarım sırasında burkulma sınır durumunun da araştırılması gerekmektedir.
Yüksek lisans tezi olarak hazırlanan bu çalışmanın amacı Çelik Yapıların Tasarım, Hesap ve Yapım Esaslarına Dair Yönetmelik 2018 ve Türkiye Bina Deprem Yönetmeliği 2018 'e göre tasarlanan kompozit kolonlardan oluşan dışmerkez çaprazlı sistemlerin deprem davranışlarının incelenmesidir. Bu çalışmada kolonları beton dolgulu kompozit kolon, yatay yük taşıyıcı sistemi dışmerkez çaprazlı çerçevelerden oluşan 8 katlı bir binaın deprem etkileri altında davranışı incelenmiştir. Model bina yönetmeliklere göre doğrusal analiz kullanılarak boyutlandırılacak ve zaman tanım alanında doğrusal olmayan analiz kullanılarak deprem etkileri altında davranışı incelenecektir.
Çalışmanın birinci bölümünde, tez çalışmasının kapsamı ve amacı belirtilmiş ve konu ile ilgili yapılmış çalışmalar incelenmiştir.
İkinci bölümde, kompozit kolonların tanımı yapılarak avantajları ve dezavantajları belirtilmiştir. Bununla birlikte kompozit kolonlu yatay yük taşıyıcı sistemlerin American Institute of Steel Construction 341.16 'a göre tasarım esasları ve mekanizma durumları yer almaktadır.
Üçüncü bölümde Türkiye Bina Deprem Yönetmeliği (TBDY-2018) 'ne göre analizlerde kullanılan doğrusal ve doğrusal olmayan hesap yöntemleri ile ilgili bilgiler verilmiştir. Ayrıca bu bölümde kullanılan malzeme modelleri, yapı elemanlarının modellenmesi, Opensees programı hakkındaki gerekli bilgiler ve zaman tanım alanında doğrusal olmayan analizlerin gerçekleştirilmesi ile ilgili detaylı açıklamalara yer verilmiştir.
Dördüncü bölümde kompozit kolonlar içeren dışmerkez çaprazlı çelik çerçeveli binanın taşıyıcı sistemi tanımlanmıştır. TBDY-2018 esasları kullanılarak yapının deprem etkileri, sistem analizi ve mekanizma durumları belirlenmiş, ÇYTHYE-2018 'de gözönünde tutularak elemanların boyutlandırılması sağlanmıştır.
Beşinci bölüm, kompozit kolonlardan oluşan dışmerkez çaprazlı yatay yük taşıyıcı sisteme sahip binanın Opensees bilgisayar yazılımı yardımı ile yapılan zaman tanım alanında doğrusal olmayan analizini kapsamaktadır.
Son bölümde, zaman tanım alanında doğrusal olmayan analizler sonunda elde edilen sonuçlar, tasarımda esas alınan prensipler doğrulutusunda değerlendirilmektedir.

Abstract:
In seismic regions, strong lateral load carrying systems are required for high-rise structures. Columns are one of the most leading structural elements for lateral load carrying systems. When the rise of structure is getting higher, stronger and consequently more place occupied columns are become necessities. With the composite columns, in the structures will be made in seismic zones it is likely to make a safer and more aesthetic resisting system. Generally, the use of composite columns to prevent usage of mega-columns and to control lateral deformation. Composite columns represent a very attractive option for the increase of building strength, stiffness and deformation capacity in structures. In this study, widespread composite columns' behaviour in an earthquake is analyzed when they are used in steel strustures as an element of lateral load resisting system.
Composite columns are categorised in two, which are concrete-encased composite members and concrete-filled composite members. Concrete-encased composite members are made from structural steel material, are the composite columns that filled with concrete in pipe or tube profiles. As for conctrete-filled composite member, they are made from structural steel material,which is I or H profiles, is covered by concrete. Concrete-filled composite members can be either circular or square or rectengular in cross section. In concrete-filled tube composite construction, the steel material increases the strength and ductility of the concrete because of its confinining effectt also concrete prevent local bucling of steel section. In concrete-encased conposite members, the concrete part delays the local buckling of the steel part and acts as fireproofing. As a concept, composite columns are similar to structural concrete's work principle. However, because of that composite columns displays higher resistance, buckling case ought to be considered.
The aim of this study, which was prepared as a master thesis, according to Turkish Structural Steel Design Code 2018 (Çelik Yapıların Tasarım, Hesap ve Yapım Esaslarına Dair Yönetmelik 2018) and Turkish Earthquake Code 2018 (Türkiye Bina Deprem Yönetmeliği 2018) is an analysis of concentrically braced frames', which are comprised of composite columns, behaviours in an earthquake. In this study, composite column whose columns are filled with concrete and their lateral load resisting systems are made from eccentrically braced frames one eight stroies structure's behaviour in an earthquake have been analyzed. According to codes, modal structures will be designed by the usage of lineer analysis and with the usage of non-lineer time history analysis in the earhquake behaviours will be analyzed.
There is no chapter on the eccentrically braced frames structures containing composite column in Turkish Earthquake Code 2018. In this study, it is desired to add eccentrically braced frames structures with composite columns section to the Turkish Earthquake Code 2018.
In the first chapter of this study, the main subject of the thesis is defined, and the scope and purpose of the study indicated. Also, the studies had been made about this topic were stated.
Second chapter covers the definition of composite columns and also their advantages and disadvantages. Having said that, according to American Institute of Steel Construction 341-16 the design fundamentals of lateral load resisting systems with composite columns and their mecanisms take place.
In the third section, according to Turkish Earthquake Code 2018, lineer and non-lineer analysis methods were indicated. Also, material models, structural element modellings, acknowledgements of Opensees Software and the details about non-linear time history analysis were explained. In nonlinear analysis, nonlinear time history analysis was performed in addition geometric and material nonlinearity was taken into consideration.
In the fourth part of this study, the structures with eccentrically braced frames' , which are made from composite columns, lateral load-resisting systems are defined. With Turkish Earthquake Code 2018 fundamentals, structures' earthquake loads, system analysis and mecanisms are stated and with Turkish Structural Steel Design Code 2018 fundamentals elements designing was made. Also in this section, design of composite columns, their interaction equations and the findings of their capacities were shown.
Composite special eccentrically braced frame systems consist of either encased or filled composite colums. Exapmle building in this study, Composite special eccentrically braced frame system consist of tube hollow structural section filled composite colums. The building has eigth stories. The first floor's story height is four meters and the other stories' story heights are three and a half meters. In plas view, the building has three openings as eight meters in X direction and the building has five opennigs as eight meters in Y direction. The structure is a high ductile eccentrically braced frame structure. Structural steel material used in the sample building is S275 which has 275 MPa yield stress and the concrete material C50 which has 50 MPa tensile stress. The sections of the beams and braces designed as HEB profiles. For secondary steel beams, IPE sections are used. Equiavalent eqarthquake load method used in linear eqarthquake analysis. In the sample model, rigid diaphram assumption was made and equivalent  earthquake force from each floor was calculated and applied to the center of gravity considering eccentricity. Equivalent seismic load method was applied by using Turkish Earthquake Code 2018 Section 4.7. In the implementation of this method, after the natural vibration period of the structure is determined, equivalent seismic forces from each floor are found. The second order effects of the structure were made by using direct analysis method and reduced rigidity was applied. Story drifts of the structure were found while non-reduced stiffnesses were used.
In eccentrically braced frame systems, lateral forces are resisted by a combination of flexure, shear and axial forces in the framing members. The link becomes the focal point in the design and detailing of an eccentrically braced frame system, as it is intended to be the primary location for the inelactic behavior in the frame. The reminder of the members and connections are intended to remain essentially elastic and required to have sufficient strength to withstand forces corresponding to the expected strenght of the link, including strain hardening. Eccentricallt braced frame systems include a reduction in the seismic base shear force due to the higher R factor than other braced frame systems, which may result in savings in the costruction of the diaphram. The link must satisfy the width-to-thickness requirements for highly ductile members. There is an exception for the flanges of short, shear dominated links with I-shaped sections. For link lengths less than 1.6Mp/Vp, the flanges need only satisfy the width-tothickness requirements for moderately ductile members.
Another consideration in the design of the link is the link length, e. Consideration of link length relates to the behavior of the link itself in the inelastic range. From simple mechanics, it can be demonstrated that when e = 2.0Mp/Vp, the yield condition is balanced between shear and flexure. For values less than 1.6Mp/Vp, the link behavior is generally controlled by shear, whereas for values greater than 2.6Mp/Vp it is controlled by flexure. To achieve shear controlled behavior, it started the design of the link using a value of 1.3Mp /Vp. This allows some flexibility in changing the link beam size and frame geometry while still maintaining a final link length consistent with the 1.6Mp/Vp goal.
Structure mechanizm is determined as the plastic deformation of the link beams by the effect of shear force. The design of the columns, braces and the beam outside of the link elements are based on the internal forces that these elements can receive due to the plastic deformation of the link beams. The diagonal brace is required to have a combined axial and flexural strength due to seismic loading equal to the forces generated by the adjusted link shear strength. The adjusted link shear strength is defined as the expected shear strength of the link, RyVn, multiplied by a factor to account for strain hardening. The design of the beam outside of the link is similar, but differs slightly from the design requirements for braces. It is also designed for the forces due to the adjusted shear strength of the link. The columns must be designed to resist the forces due to the adjusted shear strengths of all links above the level of the column.
The last and fifth chapter covers the nonlinear analysis of the structure, which have the eccentrically braced frames made by the composite columns designed in the fourth chapter, with Opensees Software.
In the nonlinear analysis model, secondary steel beams are not modeled and the masses are placed at the story end of the columns. Nonlinear beam-column elements are used in colums, beams and braces but equivalent spring pattern are used in link elements.
Eleven earthquake acceleration record were used in nonlinear analysis an these records were effected in both (X) and (Y) directions by rotating 90 degrees. These acceleration records are scaled to be compatible with elastic design spctrum.
In the last part of the thesis, with the summarizing of accounts the consequences will be compared through codes, also the consequences of lineer and non-lineer analysis results will be compared.