Çerçeve Ve Perdeli Sistemli Betonarme Binalarda Yönetmeliklere Göre Maliyet Hesabı

Abstract

Türkiye’de yürürlükte olan “Deprem Bölgelerinde Yapılacak Binalar Hakkında Yönetmelik” e göre ülke topraklarının %66’sı, nüfusumuzun %71’i, toplam belediyelerin %68 i 1. ve 2. Deprem bölgelerinde bulunmaktadır. Bu nedenle can ve mal kayıplarının fazlalığı açısından deprem, doğal afetler içerisinde ayrı bir öneme sahiptir. İmar afları ve siyasi politikalar sonucu mühendislik hizmeti almamış yapıların günden güne artması deprem bilincinin kaybolmasına neden olmuştur. Mühendislerin depreme karşı perde önlemi ilk olarak 13 Mart 1992 Erzincan depremi sonrası gündeme gelmiştir. Son yayınlanan DBYBHY-2007’de ise daha ayrıntılı ele alınmıştır. Perdeler statik anlamda yapıların yanal ötelenmelerini sınırlandırdığı gibi uygulamadaki hataları da çerçeve sistemlere nazaran daha iyi tölere edebilmektedirler. Günümüz müteahitleri arasındaki genel kanının tersine perdeler inşaat maliyetine olumlu yönde katkı yapmaktadır. Kaba İnşaat malzeme maliyetleri içinde en maliyetli kalem inşaat demiridir. Perdeli sistemlerde rijitlik, dayanım ve süneklilik çerçeve sistemlere göre daha verimli bir şekilde sağlanabilmektedir. Yüksek sünek tasarlanan perdeler demir metrajını azaltmakta, kiriş boyutlarının küçülmesine izin vermekte ve böylece beton metrajınıda etkilemektedir. Çalışmada genel hatlarıyla perdelere gereksinim nedenleri, depreme karşı dayanıklı yapı tasarımındaki önemi, inşaat maliyetine olumlu etkileri vurgulanmaktadır. Ayrıca perdelerin DBYBHY-2007’ye göre konstrüktif kuralları açıklanmaktadır. Bu kuralların kullanılan paket programlarından STA4CAD’e opsiyon yardımı ile nasıl etki ettirilecekleri, opsiyon ayarları gösterilerek anlatılmaktadır. ETABS ve STA4CAD programları ile çift çözüm yapılmış ve toplam yapı kütlesi, periyod gibi dinamik kuvvet unsurları karşılaştırılmıştır. Aynı özellikteki yapıların farklı programlarla, farklı sonuçlar vermesinin sebebi tartışılmıştır. Çerçeve sisteme, belirli bir sistematik içerisinde eklenen perdeler ile malzeme metrajlarındaki değişim belirlenerek “ Malzeme Maliyet Eğrileri” oluşturulmuş ve perde elemanların maliyete etkileri açıklanmıştır. Bu etkinin farklı zemin sınıflarında nasıl değiştiği de aynı modellerin değişik zemin sınıfı için analiz edilmesiyle yeni “Malzeme Maliyet Eğrisi” oluşturulmuştur. Çalışmanın sonuç kısmında paket programların sonuçlarının mertebe olarak kontrol edilmesi, perdelerin depreme dayanıklı yapı tasarımındaki önemli rolü ve maliyete olumlu katkıları anlatılmaktadır.

According to current regulations, Specifications for Buildings to be build in Seismic Zones, %66 of our country, %71 of our population, %68 of the municipalities are in the first or second seismic zone. Therefore, earthquake is essential because of loss of life and property. Because of the remission of development and political strategies, there are a lot of structures without engineering services therefore, earthquake consciousness disappeared. Engineers have made the wall provision for earthquake at first time after 1992 Erzincan earthquake.More details and information about the walls are given in Specifications for Buildings to be build in Seismic Zones.Walls can not only limit the horizontal displacements of structures but also tolerate the faults which make during construction period, better than the column-beam systems. Walls have benefits to coast of the construction. Rebars have the highest coast of the rough construction.About the rigidity, durability and strength, The walls are better than the column-beam systems. The wall, designed high ductility, can reduce the rebar amount and let the smaller beam dimmensions therefore coast of the concrete will be more affordable. In this study, the requirements of using walls, its importance for Earthquake Resistant Structures benefit to the coast of construction are emphasized. According to Specifications for Buildings to be build in Seismic Zones the construction rules of walls are explained. Structural informations are defined according to Specifications for Buildings to be build in Seismic Zones. Seismic Zone class is determined as Zone 1 therefore Effective Ground Acceleration Coefficient is 0.4 g. Local Site Class is Z2 therefore Spectrum Characteristic Periods are between Ta = 0.15 s. and Tb= 0.40 s. The structures were analyzed by 2 different softwares, STA4CAD and ETABS. STA4CAD is a software developed for structural engineering to determine the safety and design of a building under dead load, seismic, temperature, wind and lateral soil effects. The software can run static and RC analysis with taking into account several Turkish and international codes. The program applies matrix-displacement method with 6 unknowns for each node in 3D space.It applies rigid flooor diapghrams also. ETABS is a software that allows model creation, modification, execution of analysis, design optimization, and results review from within a single interface. Section designer allows definations of complex sections. Intended purpose of building is determined as residential therefore Importance factor of structure is taken into account as 1. Structural Behaviour Factors can change according to ductility level of structure. There are 3 types of building structural system.These are Cast-In-Situ Reinforced Concrete Buildings, Prefabricated Reinforced Concrete Buildings, Structural Steel Buildings. Structural Behaviour Factors can be classified as 2 different groups according to its ductility level. These are Systems of Nominal Ductulity Level and Systems of High Ductulity Level. Every building structural system has 4 groups and each group has 2 different structural behaviour factors. For Cast-In-Situ Reinforced Concrete Buildings, first group is Buildings in which seismic loads are fully resisted by frames, second group is buildings in which seismic loads are fully resisted by coupled structural walls, third group is buildings in which seismic loads are fully resisted by solid structural walls, fourth group is buildings in which seismic loads are fully resisted by frames and solid and/or coupled structural walls. For these groups, Systems of nominal ductulity level is 4. For second and fourth group, Systems of High Ductulity Level is 7. For first group, Systems of High Ductulity Level is 8. For third group, Systems of High Ductulity Level is 6. For Prefabricated Reinforced Concrete Buildings, first group is Buildings in which seismic loads are fully resisted by frames with connections capable of cylic moment transfer, second group is Buildings in which seismic loads are fully resisted by single storey frames with columns hinged at top.Third group is Prefabricated buildings in which seismic loads are fully resisted by prefabricated or cast-in-situ solid and/or coupled structural walls with hinged frame connections.Fourth group is Buildings in which seismic loads are jointly resisted by frames with connections capable of cylic moment transfer and cast-in-stu solid and/or coupled structural walls. For first and fourth group, Systems of nominal ductulity level is 3.For first group, Systems of High Ductulity Level is 7. For second group, Systems of High Ductulity Level is 3. For third group, Systems of High Ductulity Level is 5. For fourth group, Systems of High Ductulity Level is 6. Models are determined as High Ductulity Level , 7. 10 different models were analysed with structural informations which are explained above. Therefore the wall effect to the coast can be seen easily. After rebar and concrete quantities have been calculated, for site class Z2, rebar cost decreases %18.2 and concrete cost increases %7.3.For site class Z3, rebar cost decreases %21.5 and concrete cost decreases %8.76. As it is understood, If the number of walls increases, the rebar quantities can be reduced. Concrete coast does not change dramatically. Local site class change to Z3 from Z2 therefore, site effect can be seen. As we understood, walls benefit to coast of rough construction.These structural elements improve rigidity and strength too. When model 1 and model 10 were designed with ETABS, there are a difference about total weight of building calculated by considering Live Load Participation Factor.If all properities are same, why is there a difference between STA4ACD and ETABS? STA4CAD is a fully integrated software that can detect depth and width. Beams and columns are defined as frame elements with ETABS therefore, intersection with columns-slabs, beams-slabs calculate twice on ETABS. This is the main reason of the difference. Finally, structures always should analyse with 2 software. Results should be checked.Walls are essential to design earthquake resistant structures.