Effects of Slab Types on the Seismic Behavior and Construction Cost of RC Buildings

Öz

Reinforced concrete-framed buildings are commonly preferred to other types of buildings in Turkey. In these types of buildings, a two-way slab with beams, flat, waffle, and ribbed slab types are widely used. In building design, determining the best slab type that will perform well under gravity and lateral loads, with the least cost, is required. However, the proper selection of slab type has generally been overlooked by designers due to the emphasis on other structural members, such as beams, columns and structural walls. For this reason, the structural contribution of floors to building design has not been adequately examined. This shortcoming must be inspected in detail starting from the very first step of the design stage of a building. This study assesses the effects of different slab types on multi-story reinforced concrete buildings by investigating their structural behaviors while trying to optimize their overall cost. For this purpose, a total of 36 structural models were constructed, analyzed, and designed according to the current Turkish Building Codes and Standards. The type of slab system (a two-way slab with beams, flat, waffle and ribbed), the number of floors (10, 20 and 30), and span length (6, 7.5, and 9 m) were selected as the key parameters in these analyses. The buildings were assumed to be office buildings located in a seismically-active zone in Istanbul. The results indicated that a two-way slab with beams was the most economical slab type for 6-meter spans, while the waffle slab was the most economical for spans larger than 7.5 meters. Based on these results, the flat slab was found to be the most expensive slab type in all cases. Out of all slab types, the two-way slab with beams exhibited better earthquake performance, while the waffle and flat slabs provided relatively poor earthquake performances.  

Anahtar Kelimeler

• Multi-story buildings
• seismic behavior
• slab types
• reinforced concrete buildings

Betonarme Binaların Yapım Maliyeti ve Deprem Davranışında Döşeme Tipinin Etkisi

Öz

Türkiye’de betonarme çerçeveli binalar diğer tür yapı taşıyıcı sistemlerine göre en çok tercih edilmektedir. Bu tür binalarda kullanılan yaygın döşeme türleri ise kirişli, kirişsiz, kaset ve nervürlü olanlarıdır. Bir bina tasarımında, yatay ve düşey yükler altında en iyi performansı gösteren ve aynı zamanda en az maliyet gerektiren döşeme türünün belirlenmesi istenir. Ancak, kirişler, kolonlar ve perde duvarlar gibi diğer yapı elemanlarına analitik çalışmalarda öncelik verildiğinden, döşeme türünün uygun seçimi genellikle tasarımcı tarafından göz ardı edilir. Bu nedenle, döşemelerin bina tasarımına ve yapısal davranışına sağlayacakları katkılar yeterince irdelenmemiş olur. Ortaya çıkan bu eksikliğin ise binanın tasarım aşamasından itibaren detaylı olarak irdelenmesi gerekmektedir. Bu çalışmada çok katlı betonarme binalar üzerinde farklı döşeme türlerinin etkileri incelenirken aynı zamanda toplam maliyetin de optimumda kılınması hedeflenmiştir. Bu amaç doğrultusunda toplamda 36 bina modeli hazırlanarak, analiz ve tasarımları mevcut Türkiye bina yönetmelik ve standartlarına uygun olarak yapılmıştır. Bu kapsamda yapılan analitik çalışmalarda incelenen parametreler şu şekildedir: döşeme türleri (kirişli, kirişsiz, kaset ve nervürlü), toplam kat sayıları (10, 20 ve 30) ve tip döşeme açıklıkları (6, 7.5 ve 9 metre). Binaların tümünün iş yeri kullanımına uygun olarak İstanbul’un deprem tehlikesi içeren bir bölgesinde yer aldığı kabul edilmiştir. Yapılan analitik çalışmalara göre 6 metre açıklığa sahip binalarda en ekonomik sonucun kirişli, 7.5 metre açıklığa sahip olanlarda ise kaset döşemelerde olduğu görülmüştür. Ele alınan tüm modeller içerisinde en maliyetli çözümü üreten döşeme türü kirişsiz döşeme olarak belirlenmiştir. İncelenen tüm döşeme türleri arasında, kirişli döşemeye sahip binaların en iyi deprem performansına, kaset ve kirişsiz döşeme türlerine sahip binaların ise en olumsuz deprem performansına sahip oldukları görülmüştür.

Anahtar Kelimeler

• Çok katlı binalar
• deprem davranışı
• döşeme türleri
• betonarme binalar

Kaynakça

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