Effects Of The Column Framing Into Cantilever Beam On Seismic Performance Of Structural Systems

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013İnşaat mühendisliği açısından düzenli bir taşıyıcı sistem her zaman arzu edilse de genellikle mimari kaygılar vb. nedenlerle uygulamada düzensiz taşıyıcı sistemlere sık sık rastlanmaktadır. Taşıyıcı sistem düzensizlikleri, yönetmelikler tarafından sınırlandırılmış ve düzensiz binalar için oluşabilecek olumsuzlukların etkisini azaltmak için birtakım yaptırımlar getirilmiştir. Bu düzensizliklerin taşıyıcı sistem üzerindeki olumsuz etkisini araştırmak amacıyla DBYBHY 2007’nin düşey doğrultuda düzensizlik durumları arasında gösterdiği ve uygulanmasına izin vermediği, kolonların konsol kirişlere oturtulması durumu sunulan bu çalışmada karşılaştırmalı olarak incelenmiştir. Bu incelemede, konsola kolon oturan çerçeve türünden düzensiz bir taşıyıcı sistem ile konsol kirişleri olan düzenli bir çerçeve, son yıllarda sıkça dile getirilen performansa dayalı tasarımın temelini oluşturan doğrusal olmayan hesap yöntemlerinden statik itme analizi ve zaman tanım alanında hesap yöntemi kullanılarak irdelenmiş ve analiz sonuçları karşılaştırılmıştır. Zaman tanım alanında hesap yönteminde kullanılacak olan üç adet deprem kaydı ilgili zemin sınıfı dikkate alınarak oluşturulan tasarım spektrumuna göre benzeştirilmiştir. Sunulan bu çalışmada statik itme analizi ile zaman tanım alanında doğrusal olmayan analiz sonuçları da karşılaştırılmıştır. Ayrıca düşey doğrultuda düzensiz olan taşıyıcı sistem için zemin kat yüksekliği bir parametre olarak belirlenmiş ve zemin kat yüksekliği değiştirilerek bunun doğrusal elastik olmayan analiz sonuçlarına etkisi incelenmiştir. Bu çalışma neticesinde, düşey doğrultuda düzensiz olan taşıyıcı sistemin yatay yük kapasitesinde, düzenli yapıya kıyasla ciddi bir azalma olduğu gözlenmiştir. Taşıyıcı sistemde eleman esas alınarak yapılan değerlendirmeler sonucunda düzensiz taşıyıcı sistemde daha büyük elastik ötesi şekil değiştirmelere talep oluştuğu görülmüştür. Ayrıca düzensiz taşıyıcı sistemde karşılaştırma kriteri olan zemin kat yüksekliği arttıkça deprem tarafından talep edilen tepe yer değiştirmesi artarken taşıyıcı sistemin yatay yük kapasitesinde önemli azalma tespit edilmiştir.When a seismic ground motion occurs, the most important factor of serious damages and destructions in building is not obey the rules of current codes. Selecting a suitable carrier system at the architectural project is one of the most important tasks of engineers. To create a good carrier system is also required to have a good architectural project. Because of mistakes in building structural system, the use of the unsuitable material for the Project, poor workmanship and inadequate controls when building under construction, it is not difficult to guess our existing buildings will not show the desired performance under earthquake force. Analysis of the natural disasters that occured over the world, earthquakes cause losses of lives and property. It is the most important factor of large losses of life and property that structures built by people not has sufficient strenght to offer adequate protection againts earthquakes. Even if time and place of an earthquake is known in advance by the latest technological developments in the near future, earthquake resistant design of our buildings is required. And also thanks to the advances made in the field of civil engineering works building behaviors will interpret better and more realistic solutions will be created. The codes of earthquake is the most significant resource that can be used to build an earthquake – resistant building. According to their geographical location, their geological and sesimic characteristics that apply within the territory and local ground conditions, countries prepare regulations that includes the rules which must be followed during building design. For this purpose, The Ministry of Public works and settlement in Turkey prepare The Regulations of Buildings that will be built in Seismic Zone 2007. Seismic loads generate the most inconvenient internal forces of the structural elements. There are different methods of calculating the force of earthquakes affecting on buildings. These are called seismic load calculation methods. After determining the essential one of the methods for our system, the force of earthquakes and its distribution over structural elements must be calculated in the way the chosen method requires. Determining the suitable methods for structures are given in Turkish seismic code. Three alternative seismic load calculation methods are presented by the seismic code. “Equivalent Seismic Load Method”, “Modal Superposition Method”, and Time Increment Methods” are indicated for seismic load calculations in our seismic code. Equivalent Seismic Load Method is a widespread seismic load calculation method and it can be found in many seismic codes in the world. In Mode Superposition Method, the maximum internal forces and displacements are obtained by the calculation of the maximum contributions of each adequate vibration modes that combined statisticly. In Tıme Increment Methods, in order to investigate the structural behavior of the building under seismic loading, an earthquake is assigned to the building as lateral load and the time history analysis is carried out. To take place within the framework of the principles of earthquake – resistant design the loads on the structure should be transferred from slabs to beams, from beams to columns, from columns to foundation by the shortest path. Consequently slabs should be seated to beams, it should be pay attention to beams are continuous, two sides of beams should be supported, columns should be seated to columns, column axes and beams axes should be overlaped and it is prevented the vertical discontinuity. Among all important factors that affect the behavior of the earthquake, it is also important that structural system is whether regular or irregular. Due to irregularities in the structural system, forces that may entangle in structure can’t be transferred in structure to foundation in short path and will be cause poor regions on the system. A large number of existing buildings in Turkey and other countries, built according to design codes of the 70s and 90s shows that many of them behave poorly and have insufficient seismic safety. Importance of determination of earthquake performance of existing structures which is constructed using linear elastic method has improved. In addition to that, retrofit of unsafe structures is another subject which becomes a trend all around the world. This case contributed to the emergence of displacement – based design criteria. Because of preferring Non-linear analysis methods in the thesis, to handle more realistic behavior of the structure and analysis the developments in the field of civil engineering. In Civil Engineering, the arrangement of regular structural system is important; actually in practice, it is not possible due to some problems like architectural concerns etc. Structural system irregularities are limited by codes and some rules are set to minimize the negative effects on behavior of buildings which have irregular structural system. In this study it is examined comparatively the negative impact of these irregularities on the structural system that nonsitting the cantilever beams to columns due to “DBYBHY2007” in the vertical direction shown by the cases of irregularity and does not allow the application of these columns. And also two types of structural systems those irregular frameworks which columns supporting on cantilevers and regular frameworks which have cantilever beams are compared after examining and analyzing with the methods that static pushover analysis and time history analysis which form the basis of performance based design, mentioned frequently in recent years. The static pushover analysis is becoming a popular methods for seismic performance evaluation of existing and new structures. The expectation is that the pushover analysis will provide adequate information on seismic demands imposed by the design ground motion on the structural system. Time history analysis is another seismic calculation method for existing and new structures in our seismic code. The method makes use of earthquakes acceleration – time records that occured previously or similar artificial records which constituted. In the thesis, three earthquake records which will be used in time history analysis simulated to design spectrum as taking notice of related soil class. In the present study, the static pushover analysis and non-linear time history analysis results are compared. Furthermore, the ground floor height defined as a parameter for irregular structural system in the vertical direction and by changing the height of ground floor height, the effect of linear, inelastic analyze results are investigated. According to this study, the decrease of horizontal load capacity is observed when the building have irregular structural systems which in vertical direction in comparison regular structural system. In a structural system, as a result of the evaluations bases on the element, it is seen that an irregular system needs more inelastic deformations. Besides, it is determined when the ground floor height – the comparison parameter of irregular structural system – rises; it is observed that a significant decrease in horizontal load capacity while an increase the peak displacement that demanded by earthquake.Yüksek LisansM.Sc