Structural response relationship between scaled and prototype concrete load bearing systems using similarity requirements

Ahmet C. Altunışık,Ebru Kalkan,Hasan B. Başağa 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.4

This study is focused on the investigation for similitude the requirements between prototype and scaled models to determine the structural behavior of concrete load bearing systems. The scaling concept has been utilized in many engineering branches, has been assisted to engineers and scientists for obtain the behavior of the prototype by using scaled model. The scaling can be done for two purposes, either scaling up or scaling down depending upon the application. Because, scaled down models are the experimentation on scaled models is cheaper than huge structures. These models also provide facilities for experimental work. Similarity relationships between systems are created either by field equations of the system or by dimensional analysis. Within this study, similarity relationships were obtained by both methods. The similarity relations obtained are applied to different load bearing systems and it is determined that the similarity relation is a general expression. In this study, as an example, column, frame, cantilever beam and simple beam are chosen and 1/2, 1/5 and 1/10 scales are applied. The results are compared with the analytical results which are obtained by creating of the finite element models with SAP2000 software of different scaled load bearing systems. The analysis results of all systems are examined and it is determined that the scale factors are constant depending on the scale types for different load bearing systems.

INVESTIGATION OF LEACHATE RECIRCULATION EFFECT IN SANITARY LANDFILL SITE

( Ahmet Demir ),( Adem Baştürk ),( Bestamin Özkaya ),( M. Sinan Bilgili ) 한국폐기물자원순환학회 2002 APLAS Vol.2002 No.1

In this study, the effect of leachate recirculation on waste stabilization was investigated at Odayeri Sanitary Landfill, which locates in the European side of Istanbul. For this purpose, 1,5 hectares (test area) of the landfill area (Odayeri), and two test cells with the dimensions of 25×50×5 m. were used. Vertical injection wells method was used at test area, and surface drainage method was used at test cells for leachate recirculation. Findings obtained from this study are evaluated.

Structural behavior of arch dams considering experimentally validated prototype model using similitude and scaling laws

Ahmet Can Altunışık,Ebru Kalkan,Hasan B. Başağa 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.1

As one of the most important engineering structures, arch dams are huge constructions built with human hands and have strategical importance. Because of the fact that long construction duration, water supply, financial reasons, major loss of life and material since failure etc., the design of arch dams is very important problem and should be done by expert engineers to determine the structural behavior more accurately. Finite element analyses and non-destructive experimental measurements can be used to investigate the structural response, but there are some difficulties such as spending a long time while modelling, analysis and in-situ testing. Therefore, it is more useful to conduct the research on the laboratory conditions and to transform the obtained results into real constructions. Within the scope of this study, it is aimed to determine the structural behavior of arch dams considering experimentally validated prototype laboratory model using similitude and scaling laws. Type-1 arch dam, which is one of five arch dam types suggested at the “Arch Dams” Symposium in England in 1968 is selected as reference prototype model. The dam is built considering dam-reservoir-foundation interaction and ambient vibration tests are performed to validate the finite element results such as dynamic characteristics, displacements, principal stresses and strains. These results are considered as reference parameters and used to determine the real arch dam response with different scales factors such as 335, 400, 416.67 and 450. These values are selected by considering previously examined dam projects. Arch heights are calculated as 201 m, 240 m, 250 m and 270 m, respectively. The structural response is investigated between the model and prototype by using similarity requirements, field equations, scaling laws etc. To validate these results, finite element models are enlarged in the same scales and analyses are repeated to obtain the dynamic characteristics, displacements, principal stresses and strains. At the end of the study, it is seen that there is a good agreement between all results obtained by similarity requirements with scaling laws and enlarged finite element models.

위생매립지에서 침출수 재순환의 효과 조사

( Ahmet Demir ),( Adem Baştürx ),( Bestamin Özkaya ),( M. Sinan Bilgili ) 한국폐기물자원순환학회 2002 APLAS Vol.2002 No.2

본 논문에서 폐기물 안정성에 미치는 침출수 재순환의 효율은 이스탄불의 유럽방향에 위치한 Odayeri 위생매립지에서 조사하였다. 이러한 목적은 매립지의 1.5 hectares(실험지 역)와 25×50×5m 부피의 두 개의 실험용 셀을 이용하였다. 수직으로 주입하는 방식은 실험지역에서 사용하였고, 표면 배수 방식은 침출수 재순환을 위한 실험용 셀에 이용하였다. 본 논문에서 얻어진 결과를 평가한다. In this study, the effect of leachate recirculation on waste stabilization was investigated at Odayeri Sanitary Landfill, which locates in the European side of Istanbul. For this purpose, 1,5 hectares (test area) of the landfill area (Odayeri), and two test cells with the dimensions of 25×50×5 m. were used. Vertical injection wells method was used at test area, and surface drainage method was used at test cells for leachate recirculation. Findings obtained from this study are evaluated.

DETERMINATION OF THE REMAINING METHANE POTENTIAL OF LANDFILLED WASTES

( Adem Baştürk ),( Ahmet Demir ),( M. Siuan Bilgili ),( Bestamin Özkaya ) 한국폐기물자원순환학회 2002 APLAS Vol.2002 No.1

In this study, a comparison of methane (CH₄) generation rates for two test cells, one operated with (enhanced) and one without leachate recirculation at Odayeri Sanitary Landfill was performed by biological methane potential (BMP) test. Initial methane potential was approximately 34,5㎥ CH₄/wet ton. The remaining methane potential for the control cell (H1) and the enhanced cell (H2) is determined to be 32,6 ㎥ CH₄/wet ton and 31,1 ㎥CH₄/wet ton of refuse after 8 months of operation. Thus, H2 test cell shows more decomposition relative to the H1 test cell.

매립폐기물의 잔존 메탄 가능성 결정

( Adem Baştürk ),( Ahmet Demir ),( M. Sinan Bilgili ),( Bestamin Özkaya ) 한국폐기물자원순환학회 2002 APLAS Vol.2002 No.2

본 논문에서는 BMP 실험이 수행된 Odayeri 위생 매립지에서 침출수 재순환시설이 없는 셀과 재순환 시설을 갖춘 셀에 대하여 메탄 발생을 비교하였다. 초기의 메탄 잠재능은 대략 34,5 m3CH4/wet ton이었다. 제어되는 셀(H1) 및 강화된 셀(H2)의 잔존 메탄 잠재능은 운전 8개월 이 후 잔량의 각각 32,6 m3CH4/wet ton, 31,1 m3CH4/wet ton 이었다. 그러므로, H2 실험 셀이 H1 실험 셀에 비해 좀 더 분해가 잘 되는 것으로 나타났다. In this study, a comparison of methane (CH4) generation rates for two test cells, one operated with (enhanced) and one without leachate recirculation at Odayeri Sanitary Landfill was performed by biological methane potential (BMP) test. Initial methane potential was approximately 34,5 m3CH4/wet ton. The remaining methane potential for the control cell (H1) and the enhanced cell (H2) is determined to be 32,6 m3 CH4/wet ton and 31,1 m3CH4/wet ton of refuse after 8 months of operation. Thus, H2 test cell shows more decomposition relative to the H1 test cell.

Wave-Passage Effect on the Seismic Response of Suspension Bridges Considering Local Soil Conditions

Süleyman Adanur,Ahmet Can Altunışık,Hasan Basri Başağa,Kurtuluş Soyluk,A. Aydın Dumanoğlu 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.2

In this study, a comprehensive investigation of the stochastic analysis of a suspension bridge subjected to spatially varying ground motions is carried out for variable local soil cases and wave velocities. Bosphorus Suspension Bridge built in Turkey and connects Europe to Asia in Istanbul is selected as a numerical example. The spatial variability of the ground motion is considered with the incoherence, wave-passage and site-response effects. The incoherence effect is examined by taking into account Harichandran and Vanmarcke model, the site-response effect is outlined by using firm, medium and soft soil types, and the wave-passage effect is investigated by using 1000-2000, 500-1000, and 300-500 m/s wave velocities for the firm, medium and soft soils, respectively. Mean of maximum response values obtained from the spatially varying ground motions are compared with those of the specialized cases of the ground motion model. At the end of the study, it is seen that total displacements are dominated by dynamic component. The response values obtained for SMFF soil condition are generally the largest. When the varying local soil condition is considered, the variation of relative contributions of response components to the total response values for varying wave velocity cases is insignificant. Also, the variation of the wave velocity has important effect on the deck and towers total response values as compared with those of the constantly travelling wave velocity case. It is concluded that the site-response effect of ground motion on the response of suspension bridges is more important than that of the wave-passage, and the variation of the wave velocities depending on the local soil conditions, has important effects on the dynamic behavior of suspension bridge.

Investigating the Efficiency of Secondary Aging and Burnishing Process in Friction Stir Welded Al-7075-T6 Material

Fikret Sönmez,Hüdayim Başak,Ahmet Güral,Şehmus Baday 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.10

In this study, firstly all of Al-7075-T6 alloys were joined by the friction stir welding (FSW) method then the samples were divided into four groups. First group of samples were used directly. The second group of samples was burnished. Third group of samples were aged and the last group of samples was subjected to both re-aging and burnishing process. It was compared the tensile and bending strengths of all prepared specimens. After the FSW process, only the second aging process increased the tensile strength. There is no effect on the tensile strength of the burnishing process. The bending strength has improved only the re-aging process without burnishing operation or only burnishing without the second aging process. In the friction stir welded Al-7075-T6 materials, it was concluded not to have a significant effect on the mechanical properties of the burnishing process. However, the hardness values of the materials were increased by both the re-aging and the burnishing process.

Elevated Temperature Effect on the Dynamic Characteristics of Steel Columns and Frames

Yunus Emrahan Akbulut,Ahmet Can Altunişik,Hasan Basri Başağa,Sara Mostofi,Ayman Mosallam,Louai F. Wafa 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.3

Fire performance of load bearing elements in steel buildings such as columns and frames has major importance for structural designers. This study aims to assess the elevated temperature eff ect on dynamic characteristics of steel columns and frames by conducting sequential heat transfer and modal analyses. A series of fi nite element analyses including heat transfer analysis aere performed on 62 diff erent steel columns and frames. Three-hour part of ISO 834 fi re curve is taken into consideration in the analysis. Modal analyses are conducted for the purpose of providing a more comprehensive image of dynamic characteristics in specifi c duration of elevated temperature. The presented study accommodates the eff ect of various steel profi le types, cross-sectional dimensions and exposure durations on changes in dynamic characteristics. The outcomes of the performed parametric study revealed the decrease in natural frequencies with the temperature growth. The research has also shown the existence of a correlation between temperature variations and changes in mode shapes. The change in mode shapes depends on the profi le type. Mode shapes do not change depending on the temperature in some profi le types, while in some profi le types they change after a certain temperature. The obtained results of the performed sequential analyses are presented in forms of tabulated data and approximate formulas. They can facilitate the damage detection process and contribute in required structural health monitoring measurements while enhance the accuracy of damage assessment for fi re exposed steel structures.

Ductal Carcinoma In Situ Detected by Shear Wave Elastography within a Fibroadenoma

Fahrettin Kılıç,Fethi Emre Ustabaşıoğlu,Cesur Samancı,Ahmet Baş,Mehmet Velidedeoglu,Tülin Kılıçaslan,Fatih Aydogan,Mehmet Halit Yılmaz 한국유방암학회 2014 Journal of breast cancer Vol.17 No.2

Fibroadenoma is the most common breast tumor in women. Malignant transformation occurs rarely within fibroadenoma atolder ages. Clinicians, radiologists, and pathologists need to beaware of malignant transformation within fibroadenomas. Radiologicstudies play an important role in the diagnosis of fibroadenoma;however, radiologic findings are often nonspecific formalignancy and may appear completely benign. We detected anoccult ductal carcinoma in situ that originated inside a fibroadenomaby using shear wave elastography. We report shearwave elastography findings of ductal carcinoma in situ withinfibroadenoma and discuss the diagnostic role of this modality.