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RISS 인기검색어
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- 저자 : Seyed Ali Ekrami-Kakhki (검색결과 3 건)
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Seyed Ali Ekrami Kakhki,Ali Kheyroddin,Alireza Mortezaei 한국콘크리트학회 2022 International Journal of Concrete Structures and M Vol.16 No.5
In this essay, to investigate the progressive collapse of the reinforced concrete (RC) frames, a nonlinear static pushdown analysis was performed with column removal scenarios from the first story. At first, a numerical model was simulated and verified with the experimental model in SeismoStruct software without soil–structure interaction (SSI). Afterward, the foundation, soil, and the RC frame were modeled simultaneously in FLAC software and verified with the numerical model of the SeismoStruct software. Furthermore, the effect of SSI was studied on the progressive collapse of RC frames based on the sensitivity index (SI). The sensitivity index is defined as the ratio of the residual capacity under gravity loading of the structure by removing the column to the value of the undamaged structure. The results showed that by considering SSI, the sensitivity index decreases. Then, a parametric study of the framed structures (thickness of the foundation) and substructures (soil density, soil types, soil layers, and the soil saturation conditions) was performed to evaluate the progressive collapse-resisting capacity based on the sensitivity index. The results showed that by considering SSI, with an increase in the soil density and decrease in the groundwater level, the conditions would be better for preventing progressive collapse. It was also shown that rock and silty sands (SM), compared to other studied soil types, and SM and silty sands—silty clay with low plasticity—silty sands (SM-CL/ML-SM), compared to other studied soil layers, are better for preventing progressive collapse.
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Seyed Ali Ekrami-Kakhki,Ali Kheyroddin,Alireza Mortezaei 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.4
In this essay, the progressive collapse resistance of the reinforced concrete wall-frame structures was evaluated with and without considering the soil–structure interaction. The vulnerability of the frames against progressive collapse was investigated with the middle column removal scenario from the first story, based on the sensitivity index. To evaluate the effects of soil–structure interaction, the wall-frame structures along with the soil (hard soil) and foundation were simultaneously modeled in FLAC software and compared with the frames in Seismostruct software. The results showed that the sensitivity index decreased by considering the soil–structure interaction in the wall-frame structures. Afterward, a parametric study of the structures (foundation thickness) and substructures (soil types, soil densities, soil saturation conditions and soil layers) was performed. The results showed that with an increase in thickness of the foundation, the sensitivity index increased, and therefore, the condition of the structure would be more critical against progressive collapse. It was found that high groundwater levels in the subsoil can reduce its bearing capacity and lead to the damage to the structure. In addition, it was determined that by changing the substructure soil type from type 4 (Clay-MC) to type 1 (Rock), the use of layer 1 (SM) and layer 2 (SM-CL/ML (Very hard clay)-SM), and the soils with high density, the condition of the structures is better to prevent progressive collapse.
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Mehri-Saddat Ekrami-Kakhki,Nahid Farzaneh,Sedigheh Abbasi,Hadi Beitollahi,Seyed Ali Ekrami-Kakhki 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.5
In this research, graphene oxide was prepared by a modified Hummers’ method, and then functionalized with 1, 1′-dimethyl-4, 4′-bipyridinium dichloride (MV), and chitosan (CH) to get a MV–RGO–CH support. Pt nanoparticles were preparedon this support to get Pt/MV–RGO–CH catalyst. The morphology and microstructure of Pt/MV–RGO–CH catalyst werecharacterized with transmission electron microscopy image and X-ray diffraction analysis. The electrocatalytic activity ofthe prepared catalyst towards ethanol oxidation was investigated by carbon monoxide stripping voltammetry, cyclic voltammetry,and electrochemical impedance spectroscopy techniques. The effects of some experimental parameters such as scanrate, ethanol concentration, and temperature were investigated for ethanol electrooxidation at Pt/MV–RGO–CH catalyst. Durability of the catalyst was also investigated. The electrocatalytic performance of Pt/MV–RGO–CH catalyst for ethanoloxidation was compared with those of Pt/CH and Pt/MV–RGO catalysts. The higher electrocatalytic performance of Pt/MV–RGO–CH than Pt/CH and Pt/MV–RGO catalysts towards ethanol electrooxidation indicated that Pt/MV–RGO–CHcould be a promising catalyst for application in direct ethanol fuel cells.
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