Evalution the seismic performance of a special concentrically braced frame

First of all, it is very important to design economic and sufficiently safe buildings in the seismically critic zones. It is related with the load bearing system of the structure's non-linear behaviour and its ductility under the earthquake effects, to design sufficient safety and economically structures that is affected seismically. In the light of massive earthquakes that had happened past years, unless frame geometry and connection details are designed suitable in steel structures, they can not be perform adequately even if structural elements in high capacity in the earthquake effects. As a conclusion of all these reasons, buildings in which civil engineers design need to strong horizontally load bearing systems against the wind and earthquake effects. For lateral load resistance and seismic loads, steel braced frame systems are frequently used. The eartquake situations that is mentioned in the first paragraph is very crucial for the structure, so braced frame systems should prefer at design of load bearing system of tall steel structures because of strength of high dynamic effects. There are two types of braced systems in the CYTHYEY 2016. The first one is eccentrically braced frames and the second one is concentrically braced frames. In this study, Special concentrically braced frame (SCBF) system is used for swallowing the seismic energy. Special concentrically braced frames are widely used in steel structures as lateral load bearing system in the high level seismic zones. In this type of braced frames, even if some braces are buckled in the compression effect, there is no strength loss susbstantially in the system. As a result of this situation, special concentrically braced frames have less ductility than moment frame systems. At the same time, compression members by buckling and the tension members by yielding with tension force absorb seismic energy significantly. In brief, SCBF systems have an elastic behaviour. Additionally, since all lateral forces are conveyed by braced members, it is allowed that plastic deformations occur in this members. Therefore it demanded that columns, beams and joints is in elastic zone. In this study, special concentrically braced frame systems that are constituted for both x and y dimensions are based on CYTHYEY 2016 and draft Turkish Seismic Code (TBDY 2016). After that the structure performed by using non linear pushover and dynamic time history analysis. In the first part of the master's thesis, a general introduction is given to the subject and then general information about the purpose of the study and about the study are given respectively. After that, in the second part, some important information is given about the special concentrically braced frames and the benefits of special concentrically braced frames are discussed according to this study. By the way design principles and general rules are explained in the draft TBDY 2016. In the third part of that study, geometric characteristics of the example structure of the system, feature of load bearing system, the wind and earthquake load cases that affected the structure and their characteristics are mentioned generally. Section properties which are designed by using SAP2000 described and brace, column and beam sections and also design calculations are given in detail. Design of column and beam sections are made by using mechanism method and increased earthquake load method separataly and finally the dominant method is used. Besides, in the time that buckling of one of the braces under the compression forces, behaviour of the beams are examined in this part. These studies methods and its results are given schematically at the end of this section. In the fourth part, the structure that designed related with guide lines had been analyzing by using OpenSEES (Open system for earthquake engineering simulation). In this non linear analyze, the system was modeled in two dimensions. First of these non linear analyzes is pushover analyze. Pushover analyze was applied for four different frame models. Base shear forces (Vy) got for each frame model in consequence of non linear pushover analyze. After, coefficient of strength excess (D) and structure of the system behavioral coefficient (R) were calculated according to result of non linear pushover analyze. Second non linear analyze is dynamic time history analyze. Three seismogram that belonging to three different earthquake such as ChiChi, Kocaeli and Northridge were used in this analyze. As a result of this analyze, timewise variation of capacity ratio of brace, column and beam members was obtained for each floor. In addition, drift values were calculated for each story and also controlled for 2%. Finally, in the last part, all study is explicated briefly. Comparison of the behaviour of elements which are obtained by non linear analysis using with OpenSEES and calculations are given. All this results are discussed and evaluated.