Bölme duvarının ve bölme duvar güçlendirilmesinin çerçeve davranışına etkisi

Ülkemizde betonarme çerçeve taşıyıcı sistemine sahip binaların birçoğunun, büyük hatta orta şiddetteki depremlere dayanabilecek kalitede olmadığı bilinmektedir. Bu tip binaların deprem öncesi güçlendirilmeleri veya depremi az veya orta hasarlı atlattıktan sonra onarılması ve güçlendirilmesi pratikte oldukça yaygındır. Bu tür yapıların depreme karşı güçlendirilmesi amacıyla belli sayıda betonarme çerçevenin betonarme dolgu duvarlar ile doldurulması ekonomik bir çözüm olabilmektedir. Dolgulu çerçeve iyi analiz edilip, gerektiği gibi projelendirilir ve imal edilirse, perde duvar gibi davranarak yapının yanal rijitliğini ve dayanımı artırabilir ve böylece diğer taşıyıcı elemanların güçlendirilmesine ihtiyaç duyulmayabilir. Bu çalışma kusurlu olarak üretildikleri varsayılan yapılara ait tuğla dolgu duvarlı betonarme çerçevelerin, duvar yüzeyine uygulanan hasır donatı ve sıva ile güçlendirilmelerine yönelik deneysel çalışmayı içermektedir. Bu çalışmada 3 adet tek katlı tek açıklıklı V2 ölçekli betonarme çerçeve üretilmiştir. Numunelerden biri boş olarak deneye tabi tutulmuştur. İkinci numuneye duvar örülerek deneye tabi tutulmuş ve bölme duvar etkisi araştırılmıştır. Diğer numune ise dolgu duvar üzerine çelik hasır uygulaması 2007 TDY'de verilen parametreler esas alınarak güçlendirilmiş ve deneyler gerçekleştirilmiştir. Bu amaçla hazırlanan üç adet çerçeve elemanı, tersinir tekrarlanır yatay yük etkisi altında test edilmiştir. Bu imalatlarda tam ankastreliği sağlamak için bir rijit temel ve bu temel üzerine, tek katlı, tek açıklıklı, beton basınç dayanımı düşük, güçlü kiriş ve zayıf kolondan oluşan çerçeveler imal edilmiştir. Bu deneysel çalışmada bölme duvarının ve bölme duvar güçlendirmesinin çerçeve davranışına etkisi araştırılmış ve test edilen elemanların yatay yük taşıma kapasiteleri, rijitlik ve enerji yutma kapasitelerindeki değişim incelenmiştir.

Effect of infill walls and strengthening of the infill walls on the behavior of reinforced concrete frames

It is known that most of the reinforced concrete frame buildings in our country are not strong enough to resist the strong or even moderate earthquakes. It is very common that such structures are strengthened before earthquakes or repaired or strengthened being slightly or fairly damaged after the earthquakes. Filling a certain number of reinforced frames with infill walls in order to increase the resistance of these structures to earthquakes may be an economic solution. If the infilled frame is analyzed well, designed properly and produced accordingly, it may behave as a shear wall resulting in an increase in the stiffness and strength and hence the other structural members may not need to be strengthened. Most of the reinforced structures currently in use do not usually have enough lateral strength and stiffness, do not proper reinforcement details, and have concrete of low quality. In addition to this, the fact that there are system defects such as weak story, short column, and strong beam-weak column leads to a very large stock of buildings with insufficient earthquake resistance. It is impossible to expect that these buildings having such weaknesses will respond properly to a strong excitation. For this reason, there is need to increase the seismic safety of present building stock with an order of priority. In view of the number of buildings requiring the strengthening, it is impossible to strengthen all these buildings in a way to preserve the usability of the buildings after an earthquake. On the other hand, in order to minimize the loss of life and property, it is needed to prevent these buildings from collapsing under a strong earthquake. For the purpose of enabling the strengthening of dwellings and industrial structures in use, there is need to develop economical methods not requiring the evacuation of the structures, rapid and applicable without the interruption of the structural use. It is known that hollow-bricked walls increase both the lateral stiffness and strength of the reinforced concrete frames as long as lateral deformations do not exceed a certain threshold. Having said this, if the lateral displacements exceed a certain level, the infill walls do not play any role due to crushing and tilting and, consequently, they do not provide any resistance to response of reinforced concrete frame during the earthquake shaking. To gain more of the infill walls during an earthquake and to take advantage of their stiffness and strength enhancement, research studies on the infill walls have been carried out. This study comprises a test series of strengthening of reinforced frame with infilled brick wall which is assumed to be damaged or defective work. In this work, 3 reinforced concrete frames 'A scaled, one-bay, one-story with unreinforced infill walls were produced. One of these specimen is tested without infill walls. The second frame formed with infill wall is subjected to experiment to investigate its influence. The third frame is strengthened by applying mesh reinforcement and cover plaster on infill walls based on the parameters of 2007 Turkish Seismic Code. These above frames were tested under reversed cyclic loading. To obtain the built—in condition, frames with weak column and strong beam on a rigid continuous foundation were manufactured with low strength concrete. In this experimental study the influence of infill wall and strengthening of infill wall was investigated and changes in stiffness and lateral load carrying capacities, and energy absorption capacity were examined. By changing the bare frame into the infilled one, its lateral load carrying capacity has been increased 3.7 times and its stiffness 34 times. As such, the influence of infill walls has become apparent. The increase in the load-carrying capacity provided by the strengthening of the infill walls has also been obtained graphically. Through the strengthening of infilled wall frame with mess reinforcement and mortar, the lateral load capacity of the specimen has been increased 1.8 times. By strengthening the infilled wall frame in accordance with the Earthquake Code specifications, an increase of 80% in its lateral load carrying capacity has been obtained. Such strengthening yields an increase of around 80% in the lateral stiffness. After testing of the frame specimen, it is seen that infilled wall frame has 7 times more energy absorption capacity than the bare frame and strengthened frame 3.2 times more than infilled wall frame.

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