Yapıda malzeme seçimi için bir yaklaşım: Metal esaslı cephe kaplama malzemesi örneği
An approach to material selection in construction: A review of metal facade cladding material
Yazar: ŞAFAK GÖKTEPE
Danışman: PROF. DR. LEYLA TANAÇAN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Mimarlık Ana Bilim Dalı / Çevre Kontrolü ve Yapı Teknoloji Bilim Dalı
Derece: Yüksek Lisans, 2023
Konu: Mimarlık = Architecture

Özet:
Tasarım, malzeme ve sistemin hem kullanıcı taleplerini karşılaması hem de çeşitli başarım beklentilerini karşılayacak şekilde değerlendirilmesi ve en uygun olanın seçilmesi çok yönlü düşünülmesi gereken zor bir süreçtir. Mimarlar bir yapı tasarımı boyunca çoğu zaman bölgesel zorunlu yönetmelik ve standartlar dışındaki performans beklentilerini ve kullanıcı beklentilerini dikkate alan farklı ölçüt ve seçenekleri göz önünde bulundurmak zorunda kalmıştır. Bu süreç sonunda tüm ölçüt ve beklentilerin doğru değerlendirilmesi kullanıcı konforu ve yapının yaşam döngüsü boyunca en uygun başarımı gösterecek malzemenin seçilmesi açısından önemlidir. Malzemesi seçimi izlenecek süreç yedi aşamada özetlenmiştir. 
Bu aşamalar sırasıyla;
i) Seçim amacının belirlenmesi
ii) Amaca yönelik muhtemel seçeneklerin belirlenmesi
iii) Seçim için gerekli başarım özeliklerinin belirlenmesi
iv) Başarım ölçütlerinin belirlenmesi
v) Başarım özeliklerinin nicel ve öznel önem değerlerinin belirlenmesi
vi) Nicel ve öznel önem değerlerinin ikili kıyaslamalarının yapılması
vii) Seçeneklerin çok ölçütlü seçim yöntemi kullanarak en uygun alternatifin belirlenmesi
Çalışma kapsamında yapıda ürün ve malzeme seçimi için bir yaklaşık orta konmuş bu yaklaşım kapsamında en uygun metal esaslı cephe kaplama malzemesi seçimi yapılmıştır. İkinci aşamada belirlenen amaç doğrultusunda literatür araştırması yapılarak muhtemel seçenekler belirlenmiştir. Üçünü aşamada seçeneklerin değerlendirilmesi için metal esaslı cephe kaplamaları için başarım özelikleri belirlenmiştir. Belirlenen başarım özelikleri her bir seçenek için Cambridge Engineering Selector (CES) 2015 malzeme veritabanı kullanılarak ölçütler belirlenmiş olup bu ölçütler Analitik Ağ Süreci (AAS) çok ölçütlü karar verme yöntemi ölçeğinde 1 (en az) ila 9 (en çok) aralığında değerlere normalleştirilerek nicel önem değerleri tespit edilmiştir. Daha sonra her bir başarım özeliği için önem sıralamaları yapılmış yine aynı şekilde 1 ila 9 arasında değer alacak şekilde anket yöntemiyle mimarlara sorularak başarım özelikleri öznel önem değerleri belirlenmiştir. Altıncı aşamada belirlenen başarım özelikleri değer puanları AAS yöntemi ölçeğinde ikili karşılaştırmaları yapılarak her bir başarım özeliğinin birbiriyle sahip oldukları önem puanı farkları kadar negatif ve pozitif bağıntıları oluşturulmalıdır. İkili karşılaştırmalar sonucu elde edilen verilen AAS yöntemi seçim aracı superdecision uygulamasına veri olarak işlenmiş ve sonucunda en uygun metal esaslı cephe kaplama malzemesi seçilmiştir. Seçim için belirlenen metal esaslı cephe kaplama malzemeleri sırasıyla; titanyum-çinko, paslanmaz çelik, alüminyum, bakır ve çelik olarak belirlenmiş başarım özelikleri ise; çevresel etki değerlendirmesi, maliyet ve teknik özelikler olarak üç ana başlıkta ele alınmıştır. Teknik özelikler başarım özeliği; korozyon dayanımı, sertlik, eğilmede çekme, ısıl genleşme, güneş ışığı UV dayanımı, aşınma dayanımı ve yanma dayanımı olarak yedi alt başarım özeliğe ayrılmıştır.

Abstract:
There are various decision-making processes in building design. Through the determination of various building elements and materials, the transformation of the abstract idea in the mind of the designer into buildng is possible with the determination of the material. One of these selection processes is to determine which material will be used on the facade, which determines the identity of the building, creates its aesthetic appearance and protects the building from external effects. Today, metal- based materials are widely used due to their flexibility in design and their ability to meet various performance expectations. In order to make a choice on any subject, it is necessary to determine the options and the criteria to be used for the selection. Within the scope of this study, various sources were examined to determine the commonly used metal-based facade claddings and to examine their material properties. After determining the options and performance characteristics, it should be decided which selection tool or method will be used for the right selection. Within the scope of this study, multi-criteria decision making methods, which are widely used in many sectors, were examined. Among these methods, it was decided to use the Analytic Network Process method (ANP). The first step to be determined in the product or system selection in the structure is to create the purpose and target inputs. First of all, if there is a designer, user (customer), other stakeholders should decide together for the selection. The designer should conduct literature review and market research for the determined purpose, and inform the users and stakeholders about the possible alternatives and the required performance characteristics. Five metal-based facade cladding alternatives have been identified. These; titanium-zinc, stainless steel, aluminum, copper and steel and there are three main criteria determined for the evaluation of the selection. These; life-cycle environmental impact assessment, cost and technical specifications. The technical specifications criterion is divided into seven sub-criteria. These sub-criteria are; corrosion resistance, hardness, flexural strength, thermal expansion, radiation UV sunlight, wear resistance and flammability. After the alternatives and performance criteria are determined, which criteria are more important in comparison with each other and their degree of importance should be determined in line with the views of the designer and the user. Since there is no specific user or designer within the scope of the study, the subjective importance values of the performance characteristics determined for the most suitable metal-based facade cladding are determined by the survey method by asking the architects, master architects and doctor architects working in the sector, using the multi-criteria decision- making method and the evaluation scale of this method. After the subjective importance values of the performance features are determined by the survey method, the performance feature values of each option should be determined.
Cambridge Engineering Selector (CES) Selector 2015 Material Universe database was used for performance characteristics values (Ashby, 2015). These property values were normalized to a quantitative significance value between 1 and 9 on the ANP method scale. Quantitative significance values between 1 and 9 were determined for the performance feature of each option. The performance characteristics, subjective significance values and quantitative significance values were compared with each paired comparison, and the importance value as well as their value differences were processed into pairwise comparisons with the superdecision tool of the ANP method. After processing the data into the selection tool in pairwise comparisons, the most suitable metal-based facade cladding for performance characteristics was determined. The most suitable material was selected. In this selection, which is made with reference to performance features, it is thought to provide ease of use in determining the option that will provide the most appropriate performance throughout the life cycle of the building and create the least energy and cost loss for the users who make choices and preferences based on traditional methods based on past experiences.
In the study, respectively;
i) Literature review on material properties to identify possible material options 
ii) Literature review to determine the performance characteristics of metal-based facade cladding materials
iii) Literature review to determine the method to be used in the selection
iv) Retrieval of values from the material database to determine the criteria of performance characteristics
v) After determining the ANP method of the multi-criteria decision-making methods to be used in the selection, applying a questionnaire to the architects in order to determine the subjective importance values (local evaluation criteria) of the performance characteristics to be used in the method
vi) Determination of performance characteristics, subjective and quantitative importance value, and making comparison tables for the evaluation of options
vii) Processing the data obtained from pairwise comparisons into the ANP method selection tool superdecision application by following the steps, an example approach will be presented for the selection of the most suitable metal-based facade cladding material.
Superdecision application, which works with the ANP method, can be used for material selection at various selection levels and for different construction elements. First of all, three basic performance features for different construction elements and material selection; environmental impact and sustainability, technical features and cost should be determined and sub-headings that will meet the expected performance expectations under these three main performance features should be determined. The water absorption physical performance feature, which is not taken into consideration for metal-based facade cladding, may be an important achievement for choosing natural stone or a similar cladding material.
Environmental impact and sustainability; It is important that the material we prefer in times of energy and resource shortages is sustainable and has the least negative impact on the environment. Although there are different databases for this environmental impact assessment, the Eco-Indicator99 database, which is also used in the study, can be used for selection. According to the choice to be made, the designer and the user should jointly determine the subjective importance value of the performance feature.
Technicial Specifications; According to the place of use and purpose of the material to be used in the building, the performance characteristics that the material must meet will change. The performance characteristics expected from the material should be determined by the architect and the importance of which performance feature should be agreed with the user. After determining the subjective importance value, the criteria of various performance characteristics should be determined. In this study, CES Selector material universe (Ashby, 2015) database was used. This and similar different material databases can be used to determine the criteria.
Cost; One of the main factors affecting the design and material selection in the product selection in the building is the budget and cost. The design is shaped in line with the user's/customer's budget. In this process, how much budget will be allocated to which building element will vary according to the performance expectations that the designer will set for the customer. For which material, the importance of the cost should be determined according to the state of the budget and customer expectations.
With the help of the ANP method and superdecision application for the selection of the appropriate one among the options, it will facilitate the material selection of the architects, especially those who are new to the sector or who are just students. Choosing the most suitable material will ensure that it meets user expectations in ideal conditions and customer satisfaction, and energy and resource consumption will decrease due to the selection of materials with less environmental impact.
The superdecision application used as a selection tool within the scope of the study; It can be customized for the building industry in a user-friendly way that will facilitate material selection for architects, with the addition of an interface where material database information can be processed and subjective importance scores can be assigned. With this application, it will especially facilitate the selection of architects who are new to the sector and do not have sufficient experience in the field to be selected. However, the energy and resource consumption that may occur due to not choosing the most suitable material that meets the performance expectations will be prevented.