Kendiliğinden Yerleşen Betonun Doğrudan Çekme Dayanımına Boyut Etkisinin Araştırılması

Öz

Özellikle çekme gerilmelerinin kritik seviyede olduğu yapı elemanlarının tasarımında betonun çekme gerilmesi önemli parametrelerden biridir. Yapı şartnamelerinde çoğunlukla bahsedilen çekme dayanımı doğrudan çekme dayanımıdır. Ancak şartnamelerde ifade edilen çekme dayanımları, genellikle basınç dayanımı veya dolaylı yöntemlerle bulunan çekme dayanımlara bağlı formüllerle bulunmaktadır. Doğrudan çekme testlerinin uygulamasının zor olması ve dolaylı yöntemlerde olduğu gibi belli şartname esaslarının olmaması doğrudan çekme dayanımı ile ilgili çalışmaların sınırlı sayıda kalmasına neden olmuştur. Bu nedenle doğrudan çekme testleri ile ilgili yapılan önceki çalışmalarda teste tabi tutulan numune ebatları ve şekilleri ile ilgili belli standartlar oluşmamıştır. Bu çalışmada kendiliğinden yerleşen betonun (KYB) doğrudan çekme dayanımına boyut etkisi incelenmiştir. Bu kapsamda farklı kalınlıklarda dog-bone tipi KYB numunelerin doğrudan çekme dayanımları karşılaştırılmıştır. Deneysel doğrudan çekme dayanımları, deneysel yarmada çekme ve eğilmede çekme dayanımları ile karşılaştırılmış olup aynı zamanda TS500, Eurocode ve ACI 318 gibi yapı şartnamelerinde ifade edilen teorik çekme dayanımlarına yakınlıkları araştırılmıştır. Çalışma neticesinde numune kalınlığı ile doğrudan çekme dayanımı arasında ters orantı olduğu ve numune kalınlıklarının artmasına bağlı olarak, deneysel doğrudan çekme dayanımlarının şartnamelerde belirtilen teorik çekme dayanımlarına yaklaştığı ortaya konulmuştur.

Anahtar Kelimeler

• direkt çekme dayanımı
• boyut etkisi
• kyb

Investigation of The Size Effect of Self-Compacting Concrete on Direct Tensile Strength

Öz

The correct determination of direct tensile strength is very important in reinforced concrete building design. Unless otherwise specified in the building codes, the tensile strength that should be used in building design is direct tensile strength. However, the direct tensile strengths stated in the codes are usually found by formulas based on compressive strength, flexural tensile strength or splitting tensile strength. The fact that direct tensile tests are difficult to apply and there are no clear principles in the building codes, as in indirect methods, have led to a limited number of studies on direct tensile strength. In previous studies on direct tensile tests, certain standards were not established regarding the sizes and shapes of the samples subjected to the test. In this study, the size effect of self-compacting concrete (SCC) on direct tensile strength was investigated. In this context, direct tensile strengths of dog-bone type SCC specimens of different thicknesses were compared. The experimental direct tensile strengths were compared with the experimental splitting and flexural tensile strength, and also their proximity to tensile strengths expressed in certain building codes such as TS500, Eurocode and ACI 318 were investigated. As a result of the study, it was revealed that there is an inverse proportion between the thickness of the specimen and the direct tensile strength, and depending on the increase in the specimen thickness, the experimental direct tensile strengths approached the tensile strengths specified in the building codes.

Anahtar Kelimeler

• direct tensile
• size effect
• scc

Kaynakça

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