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    Evaluation of a Gravity Load Designed Reinforced Concrete Structure Failed Under Its Own Weight Due to Creep in Concrete
    (TRANS TECH PUBLICATIONS LTD, 2013) Kaltakci, Mevlut Yasar; Korkmaz, Hasan Husnu; Kamanli, Mehmet; Ozturk, Murat; Arslan, Musa Hakan
    Turkish building stock is commonly composed of reinforced concrete moment resisting frames. Recent earthquakes in Turkey resulted thousands of failed or heavily damaged residential houses and office buildings. In addition of the earthquake failures, reinforced concrete structures may also failed only under their own weight. There are several examples such as Hicret Apartment in Diyarbakir (1983), Zumrut Apartment in Konya, in central Anatolia, Huzur Apartment in Istanbul (2007). On February 2nd, 2004 a 9-story reinforced concrete building in Konya (Zumrut Apartment) collapsed leaving 92 people dead. The first author of the paper was governmentally charged about the investigation of the failure causes. Carrot samples were taken from the concrete columns and steel samples were obtained from the disaster area. The dimensions of the structural members were determined. The structure was modeled in three dimensional space and vertical collapse analyses were conducted. The one of the main cause of failure was determined as the creep of the concrete occurred in excessively loaded columns. The main reasons of the damages and failures were determined to be the insufficiency in material quality, mistakes made in load selection and the inappropriate load-carrying dimensions. The construction mistakes and not obeying the design drawings are the other flaws. In this paper detailed information about the structure, creep analyses and vertical collapse analyze results were depicted in understandable format.
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    Experimental study of strengthening of RC frames with column retrofitting
    (Selçuk Üniversitesi, 2014) Unal, Alptug; Balik, Fatih Suleyman; Bahadir, Fatih; Korkmaz, Hasan Husnu; Kaltakci, Mevlut Yasar; Kamanli, Mehmet
    Recently, researches related with strengthening have been increased. In most of these studies, strengthening of reinforced concrete frames with inadequate earthquake resistance was searched. However, it is known that there are buildings with inadequate earthquake resistance as well as buildings with both inadequate earthquake resistance and inadequate axial load bearing capacity. A 1/3 geometric scaled reinforced concrete frame with inadequate earthquake resistance and inadequate axial load strength modeled as a sample building was strengthened with column retrofitting and tested under vertical and lateral loads. In this study, two 1/3 geometric scaled specimens were tested under the effect of reversible repeatable lateral loads simulating earthquake. One of these samples is a bare reinforced concrete frame representing buildings with inadequate earthquake resistance and axial load strength as well as including building defects without any strengthening which are frequently encountered in our country. The second experiment element was constructed in order to represent the buildings which necessitate strengthening due to earthquake loads and axial loads. In this specimen, the columns were strengthened by retrofitting from three sides. The hysteresis curves, envelope curves, rigidity, ductility and consumed energy graphs of these tested elements are given and the differences between them were investigated and interpreted. In the final section, the experimental results obtained were evaluated, interpreted and suggestions were made.
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    Seismic behavior of concentrically steel braced frames and their use in strengthening of reinforced concrete frames by external application
    (TECHNO-PRESS, 2016) Unal, Alptug; Kaltakci, Mevlut Yasar
    There are many studies in the literature conducted on the subject of ensuring earthquake safety of reinforced concrete and steel structures using steel braced frames, but no detailed study concerning individual behavior of steel braced frames under earthquake loads and strengthening of reinforced concrete structures with out-of-plane steel braced frames has been encountered. In this study, in order to evaluate behaviors of "Concentrically Steel Braced Frames" types defined in TEC-2007 under lateral loads, dimensional analysis of Concentrically Steel Braced Frames designed with different scales and dimensions was conducted, the results were controlled according to TEC-2007, and after conducting static pushover analysis, behavior and load capacity of the Concentrically Steel Braced Frames and hinges sequence of the elements constituting the Concentrically Steel Braced Frames were tested. Concentrically Steel Braced Frames that were tested analytically consist of 2 storey and one bay, and are formed as two groups with the scales 1/2 and 1/3. In the study, Concentrically Steel Braced Frames described in TEC-2007 were designed, which are 7 types in total being non-braced, X-braced, V-braced, Lambda-braced, \- braced, /- braced and K-braced. Furthermore, in order to verify accuracy of the analytic studies performed, the 1/2 scaled concentrically steel X-braced frame test element made up of box profiles and 1/3 scaled reinforced concrete frame with insufficient earthquake resistance were tested individually under lateral loads, and test results were compared with the results derived from analytic studies and interpreted. Similar results were obtained from both experimental studies and pushover analyses. According to pushover analysis results, load-carrying capacity of 1/3 scaled reinforced concrete frames increased up to 7,01 times as compared to the non-braced specimen upon strengthening. Results acquired from the study revealed that reinforced concrete buildings which have inadequate seismic capacity can be strengthened quickly, easily and economically by this method without evacuating them.
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    Strengthening of Reinforced Concrete Frames Not Designed According to TDY2007 With External Shear Walls
    (TRANS TECH PUBLICATIONS LTD, 2013) Unal, Alptug; Kaltakci, Mevlut Yasar; Balik, Fatih Suleyman; Korkmaz, Hasan Husnu; Bahadir, Fatih; Korkmaz, Serra Zerrin; Kamanli, Mehmet
    Recently repair and strengthening of existing buildings become a popular research topic. The strengthening of buildings necessitates the evacuation of the structure. On the other hand, school, hospital type structures must continue their function. In this study exterior shear wall addition to the existing exterior frames is proposed. Since the application is applied to the exterior of the building, the structure can continue its function during the application. In this study, 1/3 scaled 4 specimens were tested under reversed cyclic loading simulating the seismic action. First reference specimen was the bare frame and didn't contain a strengthening and tested to see the reference behavior. Specimens have several design mistakes to represent the existing older structures. The other specimens retrofitted with different configurations. The second specimen was strengthened with exterior shear walls and contained a window opening. The last specimen was also retrofitted with exterior shear wall but the shear walls were divided into two pieces. The load-displacement curves, envelope curves, relative displacement curves, energy absorption curves and rigidity curves were presented and compared within the paper. In the conclusion, the capacity increase of the frame was discussed and several recommendations were presented.