Yazar "Korkmaz, Hasan Husnu" seçeneğine göre listele

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    Analysis of a multi-story reinforced concrete residential building damaged under its self-weight
    (Pergamon-Elsevier Science Ltd, 2019) Korkmaz, Hasan Husnu; Yakut, Ahmet; Bayraktar, Atilla
    Reinforced concrete framed residential buildings are remarkably common in Turkey. Observations after recent earthquakes revealed that a great portion of the present building stock has inadequate seismic resistance. Moreover, collapses of several multi-story reinforced concrete buildings under their self-weight have also been observed despite any dynamic activity. The tragic example of the collapse of the Zumrut residential building under its self-weight in 2004 and the death of its 93 occupants have highlighted the need to re-examine the structural safety of existing buildings throughout the country. In this study, a multi-story reinforced concrete building located in the same city where the Zumrut disaster occurred, has been investigated. The damage occurred under its self-weight and their causes have been studied in detail. Four columns located in the basement of this nine-story reinforced concrete building have suddenly started to crack and fracture. At this stage, the authors were invited to the building for investigation during which initiation of another column failure was observed. After securing the building, concrete test samples were taken from each floor. The building is then modeled in 3D using a finite element software. A series of analyses have been carried out based on some reasonable assumptions. The demand-to-capacity ratios for each structural member were determined and a vertical incremental nonlinear pushover analysis was performed so that the possible failure mechanisms could be determined. The results indicated that the limited reserve capacity of columns and variation in material properties led to the observed failure.
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    Buildings Damages after Elazig, Turkey Earthquake on January 24, 2020
    (Springer, 2021) Dogan, Gamze; Ecemis, Ali Serdar; Korkmaz, Serra Zerrin; Arslan, Musa Hakan; Korkmaz, Hasan Husnu
    A 6.8-magnitude earthquake that occurred on January 24, 2020, has been effective in Turkey's eastern regions. The earthquake, with recorded peak ground acceleration (PGA) value of 0.292 g, caused the destruction or heavy damage of buildings, especially in the city center of Elazig province. The purpose of this paper was to share the results of detailed investigation in the earthquake-stricken area. Additionally, the causes of damages and failures observed in the buildings were compared to those that had occurred in previous earthquakes in Turkey. In this study, the damages observed in especially RC buildings as well as in masonry and rural buildings were summarized, the lessons learned were evaluated, and the results were interpreted with reference to Turkish earthquake codes. In the study, it was particularly emphasized why the building stock underwent such damage even though the buildings were exposed to earthquake acceleration well below the design acceleration values.
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    Effect on RC buildings of 6 February 2023 Turkey earthquake doublets and new doctrines for seismic design
    (Pergamon-Elsevier Science Ltd, 2023) Ozturk, Murat; Arslan, Musa Hakan; Korkmaz, Hasan Husnu
    Two major catastrophic earthquakes, which occurred 9 h apart on the Eastern Anatolian Fault Zone and one of its branches on February 6, 2023 in Turkey, directly affected 11 provinces in the Eastern and South-Eastern Anatolia regions, where 14 million people live. These earthquakes are among the most destructive earthquakes in the history of Turkey, caused approximately 3 times more property damage and loss of life than the 1999 Marmara Earthquake. More than 24,000 aftershocks with magnitudes of up to 6.7 Mw occurred after these earthquakes. In this study, the causes of heavy destruction in some of the provinces and districts most affected by earthquakes (especially Hatay-Antakya, Kahramanmaras,, Gaziantep-Nurdagi, Gaziantep-Islahiye, AdiyamanGo & BULL;lbas,i, Malatya) were examined under sub-headings. The reasons for the damages were supported by the striking images obtained during the site investigation in the earthquake zone, and the issues that should be considered based on both seismic codes and implementations were also stated. In addition, in order to better understand the effects of earthquakes on reinforced concrete structures, the ratios of the loads acting on the structures in both earthquakes to the design load predicted by the code valid at the time the structures were built are presented in graphics. The results obtained show that the effects of design and application mistakes are quite high in the heavy destruction caused by earthquakes. But it is understood that the seismic code design criteria and requirements are insufficient in some regions. In addition, the establishment of residential areas in risky areas without taking any precautions has produced dramatic results.
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    Excessive snow induced steel roof failures in Turkey
    (Pergamon-Elsevier Science Ltd, 2022) Korkmaz, Hasan Husnu; Dere, Yunus; Ozkilic, Yasin Onuralp; Bozkurt, Mehmet Bakir; Ecemis, Ali Serdar; Ozdoner, Nebi
    In January 2017, collapses of the numerous roofs were reported due to excessive snowfall in many provinces of Turkey. In this study, the reasons behind the collapses of the steel roofs of 19 factory buildings were investigated. The steel roofs supported by the precast reinforced concrete columns indicated a similar collapse pattern to each other under the unexpected heavy snow loading. The failure mechanisms of the roofs under the snow loading were simulated numerically. Nonlinear finite element models of a typical industrial building were developed and analyzed under an incremental vertical loading that is identical to snow loading. As a result of the analysis, the vertical load carrying capacity of the roof system and the snow load level causing the collapse of roof were determined. The resulting snow load was compared with the snow load values provided by the code specifications. In addition, the collapse mechanism of the steel roof system was analytically determined and compared with the collapse modes observed in the field and the causes of the failure were evaluated. The failure mechanism and the buckling modes obtained from analyses were found very similar to those observed during the site inspections. The main reasons of the roof failures may be attributed to excessive amount of snow caused by climate change and discrepancy of designed project and as-built project due to lack of building inspection control during the construction of the buildings.
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    Seismic performance improvement of RC buildings with external steel frames
    (Techno-Press, 2021) Ecemis, Ali Serdar; Korkmaz, Hasan Husnu; Dere, Yunus
    In this study, in order to improve the seismic performance of existing reinforced concrete (RC) framed structures, various external attachment of corner steel frame configurations was considered as a user-friendly retrofitting method. The external steel frame is designed to contribute to the lateral stiffness and load carrying capacity of the existing RC structure. A six story building was taken into account. Four different external corner steel frame configurations were suggested in order to strengthen the building. The 3D models of the building with suggested retrofitting steel frames were developed within ABAQUS environment using solid finite elements and analyzed under horizontal loadings nonlinearly. Horizontal top displacement vs loading curves were obtained to determine the overall performance of the building. Contributions of steel and RC frames to the carried loads were computed individually. Load/capacity ratios for the ground floor columns were presented. In the study, 3D rendered images of the building with the suggested retrofits are created to better visualize the real effect of the retrofit on the final appearance of the fa?ade of the building. The analysis results have shown that the proposed external steel frame retrofit configurations increased the lateral load carrying capacity and lateral stiffness and can be used to improve the seismic performance of RC framed buildings.
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    Seismic performance improvement of RC buildings with external steel frames
    (Techno-Press, 2021) Ecemis, Ali Serdar; Korkmaz, Hasan Husnu; Dere, Yunus
    In this study, in order to improve the seismic performance of existing reinforced concrete (RC) framed structures, various external attachment of corner steel frame configurations was considered as a user-friendly retrofitting method. The external steel frame is designed to contribute to the lateral stiffness and load carrying capacity of the existing RC structure. A six story building was taken into account. Four different external corner steel frame configurations were suggested in order to strengthen the building. The 3D models of the building with suggested retrofitting steel frames were developed within ABAQUS environment using solid finite elements and analyzed under horizontal loadings nonlinearly. Horizontal top displacement vs loading curves were obtained to determine the overall performance of the building. Contributions of steel and RC frames to the carried loads were computed individually. Load/capacity ratios for the ground floor columns were presented. In the study, 3D rendered images of the building with the suggested retrofits are created to better visualize the real effect of the retrofit on the final appearance of the fa?ade of the building. The analysis results have shown that the proposed external steel frame retrofit configurations increased the lateral load carrying capacity and lateral stiffness and can be used to improve the seismic performance of RC framed buildings.
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    Strengthening of T-beams using external steel clamps and anchored steel plates
    (Techno-Press, 2023) Dere, Yunus; Ozkilic, Yasin Onuralp; Ecemis, Ali Serdar; Korkmaz, Hasan Husnu
    In order to strengthen the reinforced concrete T-beams having insufficient shear strength, several strengthening techniques are available in the literature. In this study, three different strengthening strategies were numerically studied. First one is affixing steel plates to the beam surfaces. Second one includes tightening external steel bars vertically similar to beam stirrups. The last one is simultaneous application of these two strengthening procedures which is particularly proposed in this work. Available experimental test series in the literature were handled in the study. Finite element (FE) models of reinforced concrete beam specimens having sufficient (Beam-1) and low shear capacity (Beam-2) were created within ABAQUS environment. Strengthened beams with different techniques were also modelled to reflect improved shear capacity. FE simulations made it possible to investigate parameters that were not examined during the previous experimental studies. The results of the analyses were then compared and found consistent with the experimentally obtained data. Experimental and FEM analysis results are in agreement between 1% (closest) and 6%. (maximum). Beam-2 was stregthened with 5 new porposed methods. The rate of increase in shear strength varies between 33% and 64%. It was found that, the strengthening techniques were fairly useful in improving the shear capacity of the considered girder. The model with the proposed strengthening alternative has accomplished a higher load carrying capacity, ductility and stiffness than all of the other models.
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    Strengthening of T-beams using external steel clamps and anchored steel plates
    (Techno-Press, 2023) Dere, Yunus; Ozkilic, Yasin Onuralp; Ecemis, Ali Serdar; Korkmaz, Hasan Husnu
    In order to strengthen the reinforced concrete T-beams having insufficient shear strength, several strengthening techniques are available in the literature. In this study, three different strengthening strategies were numerically studied. First one is affixing steel plates to the beam surfaces. Second one includes tightening external steel bars vertically similar to beam stirrups. The last one is simultaneous application of these two strengthening procedures which is particularly proposed in this work. Available experimental test series in the literature were handled in the study. Finite element (FE) models of reinforced concrete beam specimens having sufficient (Beam-1) and low shear capacity (Beam-2) were created within ABAQUS environment. Strengthened beams with different techniques were also modelled to reflect improved shear capacity. FE simulations made it possible to investigate parameters that were not examined during the previous experimental studies. The results of the analyses were then compared and found consistent with the experimentally obtained data. Experimental and FEM analysis results are in agreement between 1% (closest) and 6%. (maximum). Beam-2 was stregthened with 5 new porposed methods. The rate of increase in shear strength varies between 33% and 64%. It was found that, the strengthening techniques were fairly useful in improving the shear capacity of the considered girder. The model with the proposed strengthening alternative has accomplished a higher load carrying capacity, ductility and stiffness than all of the other models.