Mevcut betonarme bir binanın çelik kat ilavesi sonrası güçlendirilerek 2018 TBDY kapsamındaperformansının değerlendirilmesi
Evaluation of the performance of an existing reinforced concrete building retrofitted after steel floor addition under the scope of 2018 TBEC
Yazar: UFUK YILMAZ
Danışman: PROF. DR. GÜLİZ BAYRAMOĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / İnşaat Mühendisliği Ana Bilim Dalı / Yapı Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: İnşaat Mühendisliği = Civil Engineering

Özet:
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MEVCUT BETONARME BİR BİNANIN ÇELİK KAT İLAVESİ SONRASI GÜÇLENDİRİLEREK 2018 TBDY KAPSAMINDA
PERFORMANSININ DEĞERLENDİRİLMESİ
ÖZET
Dünyada meydana gelen depremlerin sonuçlarının analiz edilmesiyle birlikte yeni yapılacak binaların depreme dayanıklı tasarımı, mevcut binaların deprem etkisindeki hasar seviyesinin belirlenmesi ve depreme yeterli dayanıklılığı gösteremeyecek binaların güçlendirilmesi ile ilgili birçok çalışma yapılmıştır. Bu çalışmaların sonucunda performansa dayalı tasarım ve değerlendirme yöntemleri geliştirilmiş ve günümüzde yaygınlaşarak kullanılmaya başlanmıştır.
Ülkemiz nüfusunun yarısından fazlasının aktif deprem bölgelerinde yaşadığı düşünüldüğünde can ve mal kayıplarının önüne geçilebilmesi için gerekli tedbirlerin alınması zorunludur. Bu tedbirlerin alınabilmesi için ülkemizde tasarım ve değerlendirme kurallarını içeren yönetmelikler oluşturulmuştur.
Mevcut veya güçlendirilmiş binaların performansının değerlendirilmesi için doğrusal (Eşdeğer Deprem Yükü Yöntemi ve Mod Birleştirme Yöntemi) ve doğrusal olmayan (Tek Modlu İtme Yöntemleri, Çok Modlu İtme Yöntemleri ve Zaman Tanım Alanında) hesap yöntemleri kullanılabilmektedir.
İlk olarak "2007 Deprem Bölgelerinde Yapılacak Binalar Hakkında Yönetmelik" ile birlikte ülkemizde mevcut binaların değerlendirilmesi ve güçlendirilmesi ile ilgili bir bölüm yönetmeliğimizde yer almıştır. 01.01.2019 tarihinde yürürlüğe giren "Türkiye Bina Deprem Yönetmeliği " ile performansa göre değerlendirme ve tasarım yaklaşımı aynı zamanda yeni inşa edilecek yapıların tasarımını da kapsayacak şekilde geliştirilmiştir.
Beş bölümden meydana gelen bu tez çalışmasında birinci durum mevcut binayı, ikinci durum binaya çelik katların eklenmesini, üçüncü durum ise binanın güçlendirilmiş halini temsil etmektedir. Giriş bölümünde performansa dayalı tasarımın gerekliliğinden bahsedilmiştir.İkinci bölümde doğrusal olmayan hesap yöntemleri tanıtılarak, kullanılan malzemelerin doğrusal olmayan özellikleri anlatılmıştır. Üçüncü bölümde bina analizinde kullanılacak TBDY-2018'in tasarım esasları açıklanmıştır. Dördüncü bölümde 2007 yönetmeliğine uygun bir şekilde konut yapısı olarak inşa edilen binanın kullanım amacı hastane olarak değiştirilerek TBDY-2018'e göre PERFORM-3D programı yardımıyla "Zaman Tanım Alanında Doğrusal Olmayan Analiz Yöntemi" ile analiz edilmiştir. Bu bölümde yapının bulunduğu coğrafi koordinatları esas alan Türkiye Deprem Tehlikeleri Haritalarından (https://tdth.afad.gov.tr/) DD-1 deprem yer hareketi düzeyi için elde edilen spektrumlara göre TBDY-2018'de verilen basit ölçeklendirme yöntemi ile 11 adet gerçek deprem kaydı ölçeklendirilmiş ve daha sonra yapıya etkitilmiştir. Beşinci bölümde analizi yapılan 3 durum için sonuçlar kıyaslanmıştır. Son bölümde tezden elde edilen sonuçlar yorumlanmıştır.

Abstract:
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EVALUATION OF THE PERFORMANCE OF AN EXISTING REINFORCED CONCRETE BUILDING RETROFITTED AFTER STEEL FLOOR ADDITION UNDER THE SCOPE OF 2018 TBEC
SUMMARY
The boundaries of plates, where the plates forming the earth's crust, rub against each other, compress each other, climb on top of each other or come under them, emerge as the places where earthquakes occur. A movement occurs when the frictional force is exceeded between one plate being pushed and the other plate. This movement occurs in a very short time unit and it is a shock. Eventually, waves of earthquakes (concussion) propagate far and far away. At the same time, earth fractures can be seen, sometimes visible, extending for kilometers and called fault. These fractures can sometimes be obscured by the surface layers. According to the theories, at any point, depending on time, the energy stored elastically by the gradual unit deformation accumulation, when it reaches a critical value, overcomes the frictional force along the fault plane and forms the relative movements of rock blocks on both sides of the fault line. This event is a sudden displacement movement. Faults are generally named according to their direction of movement. The faults that occur mostly as a result of horizontal movement are called "strike slip fault". The North Anatolian Fault in our country is a strike-slip fault line.
Along with the analysis of the consequences of the earthquakes in the world, many studies have been carried out on earthquake resistant design of new buildings, determination of damage levels of existing buildings and retrofitting of buildings that do not have enough earthquake resistance performance. As a result of these studies, performance-based design and evaluation methods have been developed and nowadays it has become widespread.
Performance-based calculation methods were introduced during the end of the 20th century in the United States during the determination of earthquake reliability of structures in earthquake zones and retrofiting of structures with insufficient strenght. However, it was later found that these methods could also be used in the design of new structures.
First regulations of performance-based design were included as a chapter in Turkish Earthquake Code "Regulation on Buildings to be Built in Earthquake Zones,2007". Entered into force on 01.01.2019, "Turkey Earthquake Building Regulations" has also been enhanced to include the performance-based design of buildings to be newly built along with the evaluation and retrofitting of existing buildings.
Considering that more than half of our country's population lives in active earthquake zones, necessary precautions should be taken to prevent loss of life and property. In order to take these measures, regulations including design and evaluation rules have been established in our country.
In addition, Regulation on Design, Calculation and Construction Principles of Steel Structures undan was published in 2016 as there was a need to develop regulations on the design of steel structures. With this regulation, steel structure design has been dealt with with two different design philosophies, namely safety allowable stress
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design (ASD) and load resistence factor design (LRFD). It is expected that and load resistence factor design will be replaced with allowable stress design in the future.
Linear (Equivalent Earthquake Load Method and Mode Superposition Method) and nonlinear (Single Mode Pushover Methods, Multi-Mode Pushover Methods and Time History) calculation methods can be fulfilled to evaluate the performance of existing or retrofitted buildings.
Even though linear elastic method solution is linear, the evaluation method takes into consideration the inelastic behavior of the system. In the nonlinear assessment method, the difficulties arise in the two phases in the solution stages, since it is necessary to consider the inelastic behavior in a more realistic manner. One of these difficulties is the need for more parameters of the structural bearing system. This sometimes creates uncertainties that are difficult to overcome for existing buildings. The other difficulty is that the existing linear solution softwares cannot be used and there is a need for more detailed solution techniques. While nonlinear dynamic analysis methods are more accurate with a realistic three dimensional model with ground motions consisting of multi-component records compatible with the site-specific earthquake design spectrum, it will not be realistic to expect all engineering offices overcome this complex method for all kinds of buildings . Therefore, nonlinear static push-over analysis methods will continue to emerge as a more reasonable and simple method since they work directly with design spectrum. It should be known that when such methods deviate from reality , time history method should be applied when the damage can be predicted adequately.
The non-linear calculation methods that used to determine the performance of existing buildings under the earthquake loads, are used to calculate the plastic deformations due to ductile behavior, plastic rotations and the internal force values due to brittle behavior. Performance evaluation is made by comparing demand values with deformation and internal force capacities.
As a result of the evaluation of the performance of the existing buildings, it is possible to improve the behavior of the buildings under earthquake impact by retrofiting the buildings that do not meet the desired target performance levels.
It is appropriate to evaluate the strenghtening techniques under two general categories,first element reinforcement (techniques applied individually to the bearing elements that are found to be inadequate) and second is system behavior improvement (avoiding earthquake hazards of bearing elements by changing the general character of the structural system).
In cases of a slight number of insufficient elements or limited structural insuffciency area in the building, an element strengthening approach is required; however, in cases where the number of inadequate elements is large or if all vertical bearing elements need to be strengthened due to insufficient lateral stiffness, it is appropriate to adopt the system behavior improvement approach instead.
The strenghtening strategies for Turkey has to be based on the system behavior improvement approach because of the insufficient lateral stiffness, reinforcement arrangement faults and the use of very low quality concrete.
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As a result of such a process, since most of the seismic forces are carried by the newly formed lateral stiffness elements, the majority of the insufficient frame elements becomes sufficient because they only have to bear the forces from vertical loads. However, it is natural that a small number of bearing elements stay still inadequate or some elements to be strengtened (such as beams that turn into shear wall transverse beams) which subject to functional changes., There is no difficulty in strengthening of a small number of elements individually
Turkey has the retrofiting technology for strenghtening applications which will be applied in this approach., in most cases even offers various options to the engineers.
This approach also seems to be feasible in terms of performance level perspective.
Considering the economical situation of the country and priority of decreasing the loss of lives, this approach can easily applied according to the life safety performance level. Also, when a different performance level is selected, there is no obstacle to the apply with this approach.
In this thesis, which consists of five parts, the first case represents the existing building, the second case represents the addition of steel floors to the building, and the third case represents the retrofitted status of the building. While the necessity of performance-based design is mentioned in the introduction, In the second section, nonlinear calculation methods are introduced, also the nonlinear properties of the materials used are explained. The design principles of Turkish Earthquake Code-2018 which will be used in the analysis are explained in third section. In the fourth section, changing the intended use of an existing building which was designed and constructed as a residential building in accordance with the Turkish Earthquake Code,2007, analysis carried out by PERFORM 3D with Time History Nonlinear Analysis Method. The spectra is obtained from Turkey Earthquake Hazards Map (https://tdth.afad.gov.tr/) according to the global coordinates of the building for DD1 earthquake ground motion level. Thereafter, 11 real earthquake records scaled by the simple scaling method of TBEC-2018 and impacted to the building. In the fifth chapter, the results were compared for the three analyze cases. In the last chapter, the consequences obtained from the thesis are interpreted.