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Steel web panel influence on seismic behavior of proposed precast RCS connections
, Article Structures ; Volume 32 , 2021 , Pages 87-95 ; 23520124 (ISSN) ; Khaloo, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this study, the experimental finding of two half-scale interior prefabricated Reinforced Concrete column to Steel beam (RCS) sub-assemblage with proposed joint formations with and without web panel in the junction is presented. Previous researches about RCS have been performed to study shear strength of steel web panel in the joint by modeling joint component, however rarely have been conducted to evaluate joint shear resistance experimentally. Over the past 30 years, noticeable analytical and experimental assessments have been performed on the cast in place RCS joints, but seldom have been done on the prefabricated RCS. The steel beams in the proposed joint are attached to the expanded...
Seismic behavior of Moment Resisting Steel Beam-Precast Reinforced Concrete Column Connections
, Ph.D. Dissertation Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
In the last decades, noticeable experimental and analytical investigations have been carried out on cast-in-place Reinforced Concrete column to Steel beam (RCS) connections, however rarely have been conducted on the precast RCS. In this reaserch, test results of five half-scale interior precast RCS connections with variable joint configurations are presented. The steel beams were connected to the precast column, using face bearing plates, embedded in the connection zone. The flanges of beams were strengthened with respect to scaled section, in order to increase the load transfer to the joint. All samples were loaded under reversed displacement controlled condition. The failure mode, joint...
Analytical Evaluation of Moment Resisting Precast Concrete Beam to Column Connections by Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Khalu, Alireza (Supervisor)
Abstract
In this thesis, the behavior of proposed moment resisting precast beam-column concrete connection under cyclic and monotonic loads is investigated. In this study, the finite element models of precast and monolithic middle and corner connections are created. The results of finite element analysis under cyclic loading is verified with existing experimental results based on failure mode, ductility, energy dissipation capacity and flexural strength. Based on the results of nonlinear finite element analysis, the analytical behavior of samples is in good agreement with experimental results and finite element analysis of proposed precast connection can be replaced with supplementary tests. Then the...
Nonlinear finite element analysis and parametric study of executable RCS connections
, Article Archives of Civil and Mechanical Engineering ; Volume 22, Issue 4 , 2022 ; 16449665 (ISSN) ; Sadraie, H ; Khaloo, A ; Badarloo, B ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
This paper compares the results of a nonlinear finite element analysis (FEA) of an internal hybrid steel beam to RC column connections with those of the experiment on a half-scale. This study used extended face bearing plates (EFBP) embedded in the panel zone (PZ) to make prefabricated RC column to steel beam connections (PRCS). Steel beam flanges were made to be stronger than scaled sections to transfer more force to the PZ. Nonlinear FEA was performed with ABAQUS software to evaluate the connections under unidirectional loading. Failure mode, connection stiffness, and PZ shear strength determined by nonlinear FEA matched well with the experimental findings. PRCS1 model was used to evaluate...
Seismic performance of precast RC column to steel beam connections with variable joint configurations
, Article Engineering Structures ; Volume 160 , April , 2018 , Pages 408-418 ; 01410296 (ISSN) ; Bakhtiari Doost, R ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In the last decades, noticeable experimental and analytical investigations have been carried out on cast-in-place Reinforced Concrete column to Steel beam (RCS) connections, however rarely have been conducted on the precast RCS. In this paper, test results of four half-scale interior precast RCS connections with variable joint configurations are presented. The steel beams were connected to the precast column, using three specimens with extended face bearing plates and one with extended cover plates, embedded in the connection zone. The flanges of beams were strengthened with respect to scaled section, in order to increase the load transfer to the joint. All samples were loaded under reversed...
Failure Modes Analysis and Mechanisms for Life Extension of Gas Turbines
, M.Sc. Thesis Sharif University of Technology ;
Abstract
Currently, the relatively long time of the turbine life passes and their parts and equipment damage are different, that loss optimum performance and thus reducing their efficiency and may lead to faults and other unexpected stops in their production cycle. Process used to estimate the remaining life of the various components of this turbine is an important tool for improving the efficiency of these units to perform preventive maintenance. In the present thesis, the types of damages in different parts of gas turbines and various methods for detection of critical points, particularly finite element method, high cycle fatigue, modal analysis, methods to estimate the lifetime of a gas turbine...
Analysis and Optimization of Surge Control System of a Centrifugal Compressor
, M.Sc. Thesis Sharif University of Technology ; Mazaheri, Karim (Supervisor)
Abstract
The surge phenomenon, as the most important aerodynamic instability, has caused a severe drop in efficiency and performance in centrifugal compressors, and its prevention and control is considered one of the main concerns of industrialists. The purpose of this study is to design and develop a surge control system in order to improve the stability and safety of the system under the effect of surge. In this research, after simulating the existing control system and working line in Borzouyeh Petrochemical Industry, by designing and adding the piston surge active control system to the above centrifugal compressor and using the combined control system, the flow rate of the bypass path has been...
Effects of Water Market Formation in the Basin of Lake Urmia
, M.Sc. Thesis Sharif University of Technology ; Vesal, Mohammad (Supervisor)
Abstract
Considering that the agricultural sector is the largest consumer of water in the basin of Lake Urmia, it seems necessary to provide comprehensive methods of water resources management and formulate appropriate policies to increase water productivity in this sector. For this reason, in this research, we examine the effects of creating a water market in the basin of Lake Urmia. For this purpose, models of agricultural economics and positive mathematical programming techniques at the regional level have been used for modeling to analyze the various effects of water market creation. According to the model, the farmer chooses his cultivation pattern according to the price of the crop and the...
CFD modeling of CO2 absorption in membrane contactors using aqueous solutions of monoethanolamine-ionic liquids
, Article Industrial and Engineering Chemistry Research ; Volume 59, Issue 41 , 2020 , Pages 18629-18639 ; Darabi, M ; Ghaleh, V. R ; Bakhtiari, O ; Sharif University of Technology
American Chemical Society
2020
Abstract
The effects of addition of an ionic liquid to pure water as a physical absorbent and monoethanolamine (MEA) solutions as a chemical absorbent on carbon dioxide (CO2) absorption through hollow fiber membrane contactors were investigated using a 2D axisymmetric model. A numerical simulation was developed based on finite element method using computational fluid dynamics techniques. Liquid phase flowed in the tube side and gas mixture containing CO2 passed in the shell side of the membrane contactor in co-current and countercurrent modes. The simulation results are consistent with experimental data, and the root-mean-square error was calculated as 9 and 13% for pure water and 25 wt % for ionic...
Response to comment on 'CFD modeling of CO2 absorption in membrane contactors using aqueous solutions of monoethanolamine-ionic liquids
, Article Industrial and Engineering Chemistry Research ; Volume 60, Issue 3 , 2021 , Pages 1503-1504 ; 08885885 (ISSN) ; Darabi, M ; Ghaleh, V. R ; Bakhtiari, O ; Sharif University of Technology
American Chemical Society
2021
Kinetic behaviour of α-galactosidase produced by Absidia griseola: A comparison between free and immobilized forms of the enzyme
, Article World Journal of Microbiology and Biotechnology ; Volume 18, Issue 7 , 2002 , Pages 649-653 ; 09593993 (ISSN) ; Moazami, N ; Mirdamadi, S ; Mesgarian, R ; Vossoughi, M ; Bakhtiari, M. R ; Sharif University of Technology
2002
Abstract
In this research the characteristics of free (partially purified) and immobilized (mould pellets of Absidia griseola) α-galactosidase have been investigated. Inhibition studies of the enzyme showed that p-nitrophenol and sucrose do not have any inhibitory effect on the enzyme, but that galactose is a competitive inhibitor. In the immobilized form, inhibition was lower than in the free enzyme and the level of inhibition decreased as the temperature increased. The activity and stability of free and immobilized enzyme were investigated with respect to temperature, and the results showed that the optimal temperature range of the free enzyme was 45-50°C, while the immobilized enzyme had an...
Design and fabrication of a centrifugal microfluidic disc including septum valve for measuring hemoglobin A1c in human whole blood using immunoturbidimetry method
, Article Talanta ; Volume 190 , 2018 , Pages 134-139 ; 00399140 (ISSN) ; Saadatmand, M ; Bakhtiari, M. R ; Eghbal, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Diabetes mellitus is a global endemic with a rapidly increasing prevalence in both developing and developed countries. Recently, hemoglobin A1c has been recommended by the American Diabetes Associations as a possible substitute for fasting blood glucose for the diagnosis of diabetes, because it is an indicator of long-term glycemic control. Also, centrifugal microfluidic systems have good potential for use in the point of care testing systems. In this study, a centrifugal microfluidic disc was designed and manufactured to measure hemoglobin A1c in whole blood using an immunoturbidimetry based method. Also, a new passive valve, named septum valve, was presented to precisely control the entry...
Gas-liquid membrane contactors: Modeling study of non-uniform membrane wetting
, Article Journal of Membrane Science ; Volume 555 , 2018 , Pages 463-472 ; 03767388 (ISSN) ; Mousavi, S. A ; Bozarjomehri, R. B ; Bakhtiari, F ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Current available models for simulation of the separation process in gas-liquid membrane contactor (MC) systems consider a uniform partial membrane wetting along the membrane length (Lmem). However, transmembrane pressure changes along the Lmem. Additionally, the available models usually consider a simplified uniform pore size to represent the micro-porous MC. Additionally, not all pores in a MC have the same size. In this study, a pore-scale network model is developed to simulate the physical separation of H2S using MCs by taking to account for (i) transmembrane pressure variation and (ii) pore size distribution of MC. The model results are compared with the experimental results of H2S...
Gas-liquid membrane contactors: effects of polymer concentration and solvent type on pore size distribution
, Article Journal of Membrane Science ; Volume 563 , 2018 , Pages 813-819 ; 03767388 (ISSN) ; Mousavi, S. A ; Bozorgmehri Bozarjomehri, R ; Bakhtiari, F ; Sharif University of Technology
2018
Abstract
This study investigates the effects of polymer concentration and solvent type on the pore size distribution (PSD) of the fabricated gas-liquid membrane contactors (MCs). Eighteen flat-sheet MCs are fabricated using polysulfone (PSf) and polyethersulfone (PES) polymers, with polymer concentration of 10%, 15%, and 20%. Dimethylformamide (DMF) and n-methyl-2-pyrrolidone (NMP) solvents are used to prepare the polymeric solutions. The role of polyvinylpyrrolidone (PVP) on the mean pore size of MCs is also studied. Scanning electron microscope (SEM) analysis is applied to visualize the pore system of the fabricated MCs. Image processing technique is used to obtain the PSD of the fabricated MCs...
Bibliometric analysis of artificial intelligence revolutions in health-related sustainable development goals
, Article Health Technology Assessment in Action ; Volume 7, Issue 4 , 2023 ; 26453835 (ISSN) ; Takian, A ; Bakhtiari, A ; Rabiee, H. R ; Sazgarnejad, S ; Sharif University of Technology
Tehran University of Medical Sciences
2023
Abstract
Background: In line with the advancement of Artificial Intelligence (AI), innovative solutions have been designed to improve health-related Sustainable Development Goals (SDGs). Accordingly, there is an increasing trend in the realm of AI and SDG research areas. Objectives: This study aimed to analyze the trends and patterns of AI research in health-related SDGs using bibliometric analysis. Methods: The bibliometric approach facilitated the identification of key terms and countries from previous research. We used VOSviewer to map and analyze data obtained from three databases: Scopus, Web of Science, and PubMed. Results: Our findings illustrated that research on health has been a popular...
The effect of gap size on the microstructure and mechanical properties of the transient liquid phase bonded FSX-414 superalloy
, Article Materials and Design ; Volume 40 , September , 2012 , Pages 130-137 ; 02641275 (ISSN) ; Ekrami, A ; Sharif University of Technology
Elsevier
2012
Abstract
Optimization of transient liquid phase (TLP) bonding variables is essential to achieve a joint free from deleterious intermetallic constituents as well as with appropriate mechanical properties. In this research, TLP bonding of FSX-414 superalloy was performed using the MBF-80 interlayer. The effects of bonding time (1-30. min) and gap size (25-100 μm) were studied on the joint microstructure and its mechanical properties. Continuous centerline eutectic phases, characterized as nickel-rich and chromium-rich borides, were observed at the joints with incomplete isothermal solidification. The globular and acicular phases were seen at diffusion affected zone (DAZ). These phases could be...
Transient liquid phase bonding of FSX-414 superalloy at the standard heat treatment condition
, Article Materials Characterization ; Volume 66 , 2012 , Pages 38-45 ; 10445803 (ISSN) ; Ekrami, A ; Sharif University of Technology
2012
Abstract
The as-cast samples of FSX-414 Co-based superalloy were heat treated at the standard solution and aging heat treatment cycles. Specimens for joining were cut from the as-cast ingot. Transient liquid phase (TLP) bonding was carried out at the standard solution cycle, using MBF-30 interlayer. Also, bonded specimens were homogenized at the standard aging condition. The microstructure of the as-cast, heat treated and TLP bonded specimens were studied. These studies showed that the non-uniform distributed carbides of the as-cast specimen were replaced by uniform ones during the heat treatment. Eutectic M 23C 6 carbides were observed in all specimens. Due to the complete isothermal solidification,...
Microstructural changes of FSX-414 superalloy during TLP bonding
, Article Defect and Diffusion Forum ; Volume 312-315 , 2011 , Pages 399-404 ; 10120386 (ISSN) ; 9783037851173 (ISBN) ; Ekrami, A ; Sharif University of Technology
2011
Abstract
The as-cast FSX-414 Co-based superalloy samples were solution treated at 1150°C for 4h and then aged at 980°C for 4h. Specimens for joining were cut from the as-cast ingot and TLP bonding carried out at the same conditions as for the solution and solution+aging treatment, using MBF-30 interlayer. Microstructures were studied for as-cast, heat treated and TLP bonded specimens. These studies showed that the ununiform distributed carbides of MC type in the as-cast specimens replaced by M23C6 type carbides with uniform distribution in the heat treated microstructure. Due to complete isothermal solidification, no eutectic structure in the bond region were wasobserved, but some intermetallics in...
Microstructural study of a High Bainite Dual Phase (HBDP) steel austempered at different temperatures
, Article Defect and Diffusion Forum ; Volume 297-301 , 2010 , Pages 62-67 ; 10120386 (ISSN); 3908451809 (ISBN); 9783908451808 (ISBN) ; Ekrami, A ; Sharif University of Technology
Trans Tech Publications Ltd
2010
Abstract
4340 steel bars were austenitized at 850°C for 1 hour followed by heating at 700°C (ferrite and austenite region) for 90 min and quenching into a salt bath with different temperatures of 300, 350, 400 and 450°C. The steel bars were held for 1 hour at these temperatures before air cooling to room temperature. Various ferrite-bainite microstructures with 34% volume fraction of ferrite and different bainite morphologies were obtained. The results of SEM studies showed that by increasing the austempering temperature, the morphology of bainite varies from lower to upper bainite. According to the T-T-T diagram of the studied steel, the bainite transformation will not complete for the holding time...
The effect of bainite morphology on the mechanical properties of a high bainite dual phase (HBDP) steel
, Article Materials Science and Engineering A ; Volume 525, Issue 1-2 , 2009 , Pages 159-165 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
2009
Abstract
4340 steel bars were austenitized at 850 °C for 1 h followed by heating at 700 °C for 90 min and quenching into a salt bath at the temperature range of 300-450 °C for 1 h to obtain dual structures with 34 vol.% fraction ferrite and various bainite morphologies. SEM studies showed that by increasing the austempering temperature, bainite morphology varies from lower to upper bainite. Tensile, impact and hardness tests revealed that increasing the austempering temperature from 300 to 400 °C leads to a reduction in yield and ultimate tensile strength, hardness, uniform and total elongation and impact energy. But in dual phase steel produced by austempering at 450 °C, yield and tensile strength...