Determination of structural performance of 3D steel pipe rack suspended scaffolding systems

Güray Arslan,Barış Sevim,Serkan Bekiroğlu 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.5

This study investigates the structural performance of 3D steel pipe rack suspended scaffolding systems. For the purpose, a standard full scale 3D steel pipe rack suspended scaffolding system considering two frames, two plane trusses, purlins and wooden floor is constructed in the laboratory. A developed load transmission system was placed in these experimental systems to distribute single loads to the center of a specific area in a step-by-step manner using a load jack. After each load increment, the displacements are measured by means of linear variable differential transducers placed in several critical points of the system. The tests are repeated for five different system conditions to determine the structural performance. The means of system conditions is the numbers of the tie bars which are used to connect plane trusses under level. Finite elements models of the 3D steel pipe rack suspended scaffolding systems considering different systems conditions are constituted using SAP2000 software to support the experimental tests and to use the models in future studies. Each of models including load transmission platform is analyzed under a single loading and the displacements are obtained. In addition, to calibrate the numerical models some uncertain parameters such as elasticity modulus of wooden floor and connection rigidity of purlins to plane trusses are assessed experimentally. The results of this work demonstrate that when increasing numbers of tie bars the displacement values are decreased. Also the results obtained from developed numerical models have harmony with those of experimental. In addition, the scaffolding system with two tie bars at the beginning and at the end of the plane truss has the optimum structural performance compared the results obtained for other scaffolding system conditions.

Construction stages analyses using time dependent material properties of concrete arch dams

Barış Sevim,Ahmet C. Altunışık,Alemdar Bayraktar 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.14 No.5

This paper presents the effects of the construction stages using time dependent material properties on the structural behaviour of concrete arch dams. For this purpose, a double curvature Type-5 arch dam suggested in ‘‘Arch Dams’’ symposium in England in 1968 is selected as a numerical example. Finite element models of Type-5 arch dam are modelled using SAP2000 program. Geometric nonlinearity is taken into consideration in the construction stage analysis using P-Delta plus large displacement criterion. In addition, the time dependent material strength variations and geometric variations are included in the analysis. Elasticity modulus, creep and shrinkage are computed for different stages of the construction process. In the construction stage analyses, a total of 64 construction stages are included. Each stage has generally 6000 m3 concrete volume. Total duration is taken into account as 1280 days. Maximum total step and maximum iteration for each step are selected as 200 and 50, respectively. The structural behaviour of the arch dam at different construction stages has been examined. Two different finite element analyses cases are performed. In the first case, construction stages using time dependent material properties are considered. In the second case, only linear static analysis (not considered construction stages) is taken into account. Variation of the displacements and stresses are obtained from the both analyses. It is highlighted that construction stage analysis using time dependent material strength variations and geometric variations has an important effect on the structural behaviour of arch dams. The maximum longitudinal, transverse and vertical displacements obtained from construction stages and static analyses are 1.35 mm and 0 mm; -8.44 and 6.68 mm; -4.00 and -9.90 mm, respectively. In addition, vertical displacements increase from the base to crest of the dam for both analyses. The maximum S11, S22 and S33 stresses are obtained as 1.60MPa and 2.84MPa; 1.39MPa and 2.43MPa; 0.60MPa and 0.50MPa, respectively. The differences between maximum longitudinal, transverse, and vertical stresses obtained from construction stage and static analyses are 78%, 75%, and %17, respectively. On the other hand, there is averagely 12% difference between minimum stresses for all three directions.

Assessment of 3D earthquake response of the Arhavi Highway Tunnel considering soil-structure interaction

Barış SEVİM 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.11 No.1

This paper describes earthquake response of the Arhavi Highway Tunnel its geometrical properties, 3D finite element model and the linear time history analyses under a huge ground motion considering soil-structure interaction. The Arhavi Highway Tunnel is one of the tallest tunnels constructed in the Black Sea region of Turkey as part of the Coast Road Project. The tunnel has two tubes and each of them is about 1000 m tall. In the study, lineartime history analyses of the tunnel are performed applying northsouth, east-west and up accelerations components of 1992 Erzincan, Turkey ground motion. In the time history analyses, Rayleigh damping coefficients are calculated using main natural frequency obtained from modal analysis. Element matrices are computed using the Gauss numerical integration technique. The Newmark method is used in the solution of the equation of motion. Because of needed too much memory for the analyses, the first 10 second of the ground motions, which is the most effective duration, is taken into account in calculations. The results obtained 3D finite element model are presented. In addition, the displacement and stress results are observed to be allowable level of the concrete material during the earthquakes.

A new developed approach for EDL induced from a single concentrated force

Barış Sevim,Serkan Bekiroğlu,Güray Arslan 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.5

In this study, it is presented that a new developed approach for equivalent area-distributed loading (EADL) induced from a single concentrated force. For the purpose, a full scale 3D steel formwork system was constructed in laboratory conditions. A developed load transmission platform was put on the formwork system and loaded step by step on the mass center. After each load increment, displacement was measured in several crictical points of the system. The developed platform which was put in to slab of formwork to equivalently distribute the load from a point to the whole slab was constituted using I profiles. A 3D finite element model of the formwork system was analyzed to compare numerical displacement results with experimental ones. In experimental tests,difference among the displacements obtained from reference numerical model (model applied EADL) and main numerical model (model applied single load using a load cell via load transmission platform) is about %13 in avarage. Difference among the displacements obtained from experimental results and main numerical model under 30 kN single load is about %11 in avarage. The results revealed that the displacements obtained experimentally and numerically are dramatically closed to each other. It is highlighted from the study that the developed approach is reliable and useful to get EDL.

Electrodeposition of CdS Thin Films at Various pH Values

Barış Altiokka,Ayça Kıyak Yildirim 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.6

The effects of pH value on CdS thin films fabricated by using electrodeposition were investigated in detail. The pH values of the final solutions were adjusted between 1 and 5. Aqueous solutions of HCl and NaOH were used to adjust the pH. The reaction rates were changed by the pH due to the fact that the pH affected the rate of release of sulphide from sodium thiosulfate. The structural, optical and morphological properties of the films were analyzed by using X-ray diffraction, Ultraviolet-visible spectroscopy and scanning electron microscopy, respectively. Compact films with good crystallinity were obtained at pH value of 4 and 5.

Investigation of the mechanical properties of the diffusion welded copper wires stacked in the same direction

Ömer Barışkan Yasan,Sedat Özden,Fehmi Nair 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1

This study is made to obtain controllable and improved microstructural properties of a material obtained by stacking copper wires and then combining them with hot diffusion welding. The mechanical performance of the new approach to obtain a copper billet was assessed and accordingly the diffusion welding parameters were optimized. Samples with a dimension of 60×40×5 mm were produced by stacking. Copper wires with different diameters were stacked in the same direction and welded with hot diffusion welding under 69.5-139-208.5 MPa pressures, for 20-60-90 minutes, at 600 °C. Strength of the bonding was tested by bending and microhardness tests. In addition, the diffusion interface was examined by optical microscope and SEM. The interfacial bond strength after welding increased with temperature, pressure and time. Especially, the increase in diffusion time actuated the formation of common grains in the fusion area by decreasing or completely eliminating the interfaces of the wires.

Neuro-fuzzy modelling methods for relative density prediction of stainless steel 316L metal parts produced by additive manufacturing technique

Can Barış Toprak,C.U. Dogruer 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1

Two machine learning (ML) methods, adaptive neuro fuzzy inference system (ANFIS) and artificial neural networks (ANN) have been implemented to predict the relative density (RD) of stainless steel 316L parts which are produced in additive manufacturing (AM) machines. The objective of this paper was to create ML models adapted for AM technique to verify the generalized model that predicts RD with the least error. Some important process parameters in AM such as scanning speed, laser power, hatch distance and layer thickness were picked as input and RD was set as output. Effects of the input parameters on RD were discussed and they were represented in the form of surface plots. It has been found that ANN method‘s convergence rate was better than that of ANFIS method, which confirms that usage of neural networks is a better choice than the usage of fuzzy reasoning in modelling AM technique.

The effect of intraoperative neuromonitoring on the number of lymph nodes excised and recurrence when applied during neck dissection in cases of papillary thyroid cancer

Bülent Çomçalı,Barış Saylam,Buket Altun Özdemir 대한외과학회 2022 Annals of Surgical Treatment and Research(ASRT) Vol.102 No.2

Purpose: The aim of this study was to evaluate the effect of neuromonitoring on the number of lymph nodes (LNs) removed when applied during neck dissection. Methods: A total of 166 patients receiving neck dissection due to papillary thyroid cancer were separated into 2 groups (monitoring group, n = 76; non-monitoring group, n = 90). Results: The number of LNs dissected was observed to be statistically significantly higher in the monitoring group (P = 0.001), and the difference between the groups in the number of positive LNs was significant (P = 0.031). There was seen to be a negative relationship between the number of positive LNs dissected and recurrence (r = –0.404, P = 0.005). Conclusion: Intraoperative neuromonitoring during neck dissection makes a positive contribution to the prevention of the development of recurrence by increasing the number of LNs excised and the number of metastatic LNs.

Conducting Large-scale Model Experiments on Xanthan Gum Treated Clay as an Eco-friendly Approach to Soil Improvement

Baki Bağrıaçık,Barış Mahmutluoğlu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.4

Recently, waste utilization in soil improvement has become immensely popular regarding the optimization of waste disposal, economy, and environmental protection. Most industrial wastes are environmentally hazardous. In this study, xanthan gum, which is an eco-friendly biopolymer, was utilized in soil improvement. Model experiments were carried out to investigate influences of water content, optimum xanthan gum ratio, blending technique, enhancement thickness and curing duration. Consequently, approximately 4.47 times bearing capacity improvement and 3.5 times settlement reductions were attained. Besides, optimum values of 1.75% for the biopolymer ratio, 80°C for the mixing temperature, 42 days for the curing period and 0.75% for the improvement depth were determined. The findings of micro-structural analyses also stood up for the existence of chemical and physical improvements in the soil structure.

Observation of behavior of the Ahlat Gravestones (TURKEY) at seismic risk and their recognition by QR code

Ercan Işık,Barış Antep,Aydın Büyüksaraç,Mehmet Fatih Işık 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.5

Protection of cultural heritage and carrying it to the future are at the top of the significant topics of research and implementation in engineering in the 21st century. There are several historical structures in the district of Ahlat located in the east of Turkey on the Lake Van Basin that has harbored many civilizations. Some of such works are the gravestones that are found in the Ahlat Seljuk Cemetery, which is the oldest and largest cemetery in the district. This study firstly provides information about the Ahlat Seljuk Cemetery and the gravestones found in it. Observation-based structural analyses were carried out on these gravestones that are found in this area that are known to have belonged to different civilizations based on their physical and constructional characteristics. These stones were built out of Ahlat stone as single pieces. Information is provided on the damages that have occurred on the gravestones in time and their causes. In general, losses of mass, abrasions, separations, collapses and calcifications due to natural conditions, as well as vegetative formations, were observed in the gravestones. To provide an example of other gravestones within the context of the study, the gravestone that is known to belong to the person named Nureddin Ebu Hasan was selected. As a result of the modeling that was carried out for this gravestone by using the finite elements method, modal analyses were carried out. With these analyses, for the gravestone, period, effective mass participation rates and stress values were calculated. The stress values that were obtained in this study were compared to the material safety stress values that were obtained in previous studies. Additionally, QR code application was created for the gravestone that was selected as an example in the study, and information on this gravestone was transferred to an electronic environment. The QR code application includes different language options, visuals of the gravestone and information on the gravestone. The QR application was also supported with a video of the cemetery where the gravestone is located. With this application, access to information about gravestones will be possible by using tablets and smartphones. With a QR code to be created for each gravestone, these gravestones will obtain identity cards.