4-8 katlı konut yapılarında taşıyıcı sistem maliyetini tahmine yönelik bir yaklaşım önerisi

Abstract

Dünyada bugün her şeyin en iyisini yapmakla beraber bunu ekonomik yapmak genel bir amaç olarak sayılmaktadır. Bunun ya nında kaynakların da giderek azaldığı dikkate alınırsa ekonomi, malzeme, işgücü ve araç-gereç yönünden en çok uyulması gereken unsur haline gelmiştir. Malsahibi ile mimar arasındaki ilişki de günümüzde paraya dayanmaktadır. Mimarın tasarladığı bina fonksiyonel ihtiyaçları her ne kadar sağlıyorsa da müşteri düşündüğünden fazla para harcamış ise mimar tasarımında başarısız görünür. Müşterinin istekleri içinde binanın toplam maliyetinin daha önce kendisine belirtilen tahmini geçmemesi veya bu tahmine yakın olması vardır. Ayrıca bina kendisi için kabul edilebilir bir maliyete çıkmalıdır. Görüldüğü gibi yukarıda sayılan neden lerde müşterinin belirgin bir maliyet kaygısı hissedilmektedir. Bina maliyeti olarak ilk yatırım maliyetinden yok etme maliyeti ne kadar olan maliyetler zincirinde inşaat maliyeti hiç kuşkusuz binanın oluşumu göz önüne alındığında en büyük paylardan birine sahip olacaktır. Tübitak Yapı Araştırma Enstitüsü ' nün yapmış olduğu araştırmada maliyet yüzdeleri açısından binanın taşıyıcı sistemi, toplam bina inşaatında %40'ı aşan bir paya sahiptir. Bu çalışmada taşıyıcı sistemi etkilediği düşünülen bazı tasarım değişkenlerinin kullanıcıya yaşatacağı mekanlar açısından mima rın tasarımına etken olacağı düşünülmüştür. Bu çalışmada maliyet tahmin modellerinden tanımlayıcı mo del olan korelasyon tekniği ile tasarımcıya önemli kararlarını verirken bu tasarım değişkenlerinin maliyeti nasıl etkilediğini göstererek yardımcı olacak bir öneri sunulmuştur. Ele alman inşaatı bitmiş örnek 30 projenin, metrekare birim taşıyıcı mali yeti ile şu tasarım değişkenleri arasında ilişkiler aranmıştır: 1. Bina toplam alanı. 2. Binanın normal kat alanı. 3. Binanın kat sayısı. 4. Binada çıkma yönü. 5. Binada zemin oturum alanı. 6. Binanın temel sistemi. 7. Binanın kolon-perde yüzdesi. 8. Kirişlerde saplama- süreklilik yüzdesi. 9. Binanın döşeme tipi. 10. Binada çekirdeğin yeri. Böylece mimara daha tasarımının ilk başlarında maliyet ta vanını aştırmayacak bir takım ipuçları vermek mümkün olacaktır. Bu yöntem sayesinde mimar tasarımıyla, müşteri de parasıyla daha gerçekçi düşünme imkanına sahip olacaktır.

From the earliest times people have needed some idea of what a new building was going to cost before they started to work on it. After traditional settled economic and social order has turned into something more sophisticated and dynamic, the clients needs has turned upside-down as well. Economic and social development of the 20th. century has made money an adorable item. In according to this progress, the building clients' main needs has changed also relationed with money. The architect and other design consultants would have completed most of their work and would require a substantial proportion off their fees, as would the quantity surveyor, irrespective of whether the job went ahead or not. In addition the client would probably have bought the land for the project and this money would now be locked up in an unproductive asset, in addition to which he might have made plans for the use of the building which would have to be abondoned with consequent loss. An alternative to abandonment of course, would be complete redesign on a more modest scale and the seeking of fresh tenders but this would involve a further loss on time and would not relieve the client the abortive expenditure on the first scheme. It was therefore important that the client should have a good idea of what the building was likely to cost before he had committed himself very far, and this was done by the means of an "approximate estimate". This was an attempt to forecast the cost of a building at seme stage. prior to the completion of the Bill of Quantities. The client is always anxious to have seme idea of his commintments as early as possible, and the architect wants to know whether his design was financially possible before he had gone too far with it. Today the contact between client the owner and architect the designer based on money. Therefore in spite of architect's design corresponds every functional need, if the client spends ?VI»- Every building client will have a set of needs, some of which are more important to him than others. A confirmed cynic once described architecture as the design of beautiful buildings that satisfy only the architect and not the client. The success of any construction project can be measured against several different criteria. The requirement's can be summarized as follows and a successful combination of these factors is necessary in order to provide a project for a satisfied client: 1. Performance Appearance Quality Function Durability Maintenance 2. Time Design Length Start Date Hand-Over Completion 3 - Cost Budget Estimate Tender Final Account Cost-in-use In order to understand the fact better, let's summarize the client needs in the following: 1. The building must correspond the client's needs. If not, the architect would be unsuccessful in his design. 2. The building must be ready to work the time which contract determine. 3. The total cost of the building must be equal or closer to the estimated cost which has given to the client at the design stage. -via- As seen in these sentences, the client has an evident anxiety of the building cost. The total cost of the building can be summarized simply as follows : a. Cost of land. b. Legal etc. costs of acquiring and preparing the site. c. Demolition or other physical preparation of the site. d. Building cost. e. Professional fees in connection with last. f. Furnishings, fittings, machinery, etc. g. Costs in connection with disposal (sale, letting, etc..) where the building is to be disposed of that completion. h. Cost of financing the project (this principally represents interest, on the moneys expended before any return is obtained either by of income or of use. i. Cost of management, running and maintenance where the building is to be retained by the client, for sue or only partially disposed of, or where the building is let to a tenant but the owner has made himself responsible for some or all of these costs. It is important to realize that "building cost" is only one of nine items of total cost which is paid by the client, and that in end it is the total which count. Being just one of those nine items does not make building cost an unimportant item. Because the building is what you get after the work has done totally. And the very important percentage of the clients money has gone to the building's physical cost. Materials, manpower and machinery are the main expenses of the building cost. The Turkish Scientific and Technical Research Association's Building Research Institute has made a research of cost percentages of building cost. The percentages of the elemental units in a building are as follows: -VIÎİ- 1. Sub-covering %14. 4 2. Side-covering % 8.9 3. Upper-covering % 9.3 4. Frame %17.2 5. Horizontal Partition %19.2 6. Vertical Partition % 7.2 7. Vertical Connection % 1.9 8. Equipment % 0.2 9. Installation %12.9 10. Outer Works % 3.0 11. Transportation % 6.7 TOTAL %100.0 As seen above the cost of construction which carries all of the building and contains frame and horizontal partition of the building has a total percentage nearly %40. This explains the importance of construction cost in total cost of the building. The research of the Institute Of Building Research contains reinforced buildings made by frame technology. In a statistical manner, The Institute Of Statistics Of The Prime Ministry Of The Turkish Republic has made a research and they reached to a conclusion of Reinforced Concrete Frameworks preference in Türkiye has a percentage of 82%, the massive work has 18% and the others has nearly a zero percent in house construction. In this work of thesis, it is believed that some constructional design variables has a relationship with the cost of the building. These design variables are very effective factors to the architect's design in means of living places which are designed for the client. This work has an aim of giving some clues of cost with these constructional design variables at the design stage to the architect, so he wouldn't pass over the cost limit. The architect's main problem is not knowing the amount of money in the client's pocket and how much he's going to spend, as well as design. -?x- In this work the construction design variables are accepted and searched as follows: 1. Total area of the building. 2. The ratio of the characteristic floor area to the total area of the building. 3. The ratio of ground floor area to the total area of the building. 4. The storey number of the building. 5. The console direction of the building. 6. The foundation system of the building. 7. The ratio of the area of curtain walls to the total area of the vertical construction. 8. The ratio of the number of secondary beams to the total number of beams in a characteristic flat of the building. 9. The floor type of the building. 10. The place of the stairway of the building. It is believed that these design variables has a relationship with the construction cost of the building. In this work, this relationship is searched by a descriptive cost model. The correlation method is used in this model. The correlation is searched between the unit cost of construction and the design variables which are told above. Using this method, will make the architect think much more realistic with his design and will also make the building client think much more realistic with his money.