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Evaluation of Seismic Performance Factors for High-Rise Steel Structures with Diagrid System
Morteza Sohrabi-Haghighat,Payam Ashtari 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.11
Diagrid system is a new tubular structural system in tall buildings which requires seismic performance factors (R, Ω0, Cd) for seismic design according to the loading and design codes. By considering the fact that the current codes do not include these factors, this paper aims to evaluate them based on the FEMA P695 methodology. For this purpose, five archetypes have been developed in a way that the structure story heights and span lengths are respectively equal to 4 and 6 meters; this makes the diagonal angles equal to 53.13 degrees. The response modification coefficient (R-factor) of the archetypes was calculated by the Uang method through iteration in analysis and design in OpenSees and ETABS software, respectively. Two types of analysis were carried out: non-linear static analysis (pushover analysis) and non-linear incremental dynamic analysis (IDA); the first evaluates ductility, μT, and over-strength factors, Ω, and the second evaluates “collapse margin ratio (CMR)”. At the end, computed “adjusted collapse margin ratio (ACMR)” was controlled by acceptable values of ACMR in the FEMA P695. Based on the results, the values of R-factor, over-strength factor, Ω0, and deflection amplification factor, Cd, are proposed to be 2.5, 2.0 and 2.5, respectively.
Morteza Mohammadi,Tahmoores Sohrabi 대한산업공학회 2018 Industrial Engineeering & Management Systems Vol.17 No.4
In the business environment, technological change, information technology and new business practices are increasing. The customer is considered as a valuable asset. So, customer orientation and customer preservation are considered as astrategy for creating competitive advantage. Organizations will be successful only if they satisfy their customers. Therefore, this research aims to achieve a mechanism adapted to new e-commerce methods to investigate the effect ofmarketing mix elements on customer satisfaction with the presence of the mediating variable of electronic customerrelationship management. The present research is an applied study conducted with using the descriptive-correlationalmethod. The sample size is 384 people from all of the customers who referred to the active electronic stores in thetime period of collecting the research data and purchased their products. The tools used in this research were standardmarketing mix questionnaire, customer satisfaction questionnaire, and standard customer relationship managementelectronic questionnaire. The reliability of them by Cronbach’s alpha was 0.82, 0.83 and 0.92, respectively. Confirmatoryfactor analysis method was used for investigating the validity. The data were analyzed by using Pearson correlationand structural equation modeling. The results showed that the marketing mix elements have a positive and significanteffect on customer satisfaction with the presence of intermediary variable of customer relationship management. This can maintain customers, satisfy them, and attract new customers.
Comparison of the Nutritional Status Assessment Methods for Hemodialysis Patients
( Zahra Sohrabi ),( Atefeh Kohansal ),( Hanieh Mirzahosseini ),( Moein Naghibi ),( Morteza Zare ),( Neda Haghighat ),( Marzieh Akbarzadeh ) 한국임상영양학회 2021 Clinical Nutrition Research Vol.10 No.3
Protein-energy wasting (PEW) is prevalent among hemodialysis (HD) patients and is associated with poor outcomes. There are various methods for nutritional status evaluation in HD patients. Each method has its own advantages and disadvantages. We aimed at comparing the method validities of normalized protein catabolic ratio (nPCR) and malnutrition universal screening tool (MUST) with subjective global assessment (SGA) in HD patients. We examined 88 HD patients using SGA and MUST questionnaires. The nPCRs were calculated using pre-dialysis and post-dialysis BUN and Kt/v. Also, PEW of patients was assessed based on the criteria of the International Society of Renal Nutrition and Metabolism. Methods' specificity, sensitivity, and precision rates were assessed. Correlations between methods were analyzed using Pearson-correlation. Based on the SGA, MUST, and nPCR methods, almost 41%, 30%, and 60% of patients had malnutrition, respectively. According to the criteria, more than 90% of patients had PEW. SGA was positively and significantly associated with MUST (p ≤ 0.001). Sensitivity for SGA, MUST, and nPCR methods were 100%,100%, 1.8%, and their specificity were 98%, 98%, and 4%, and their precision rates were 99.7%, 98.7%, and 3%, respectively. From various methods of nutritional assessment (SGA, MUST, and nPCR), compared to SGA as the common method of nutrition assessment in hemodialysis patients, MUST had the nearest specificity, sensitivity, and precision rate and nPCR method had the lowest ones. nPCR seems to be a flawed marker of malnutrition and it should be more investigated if MUST can be used instead of SGA.
The effect of beam section property on the behavior of modular prefabricated steel moment connection
Seyed Morteza Kazemi,Mohammad Reza Sohrabi,Hasan Haji Kazemi 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.32 No.6
The specially prefabricated steel moment connections with pyramid head is one of the significant innovations in the steel structures forms to improve the installation time and simplify the construction procedure. The beams in this structure form are supported by two top and bottom angles and web double angles. Such a configuration despite its advantages increases the welding operation and filed installation time and costs. In this paper, the effect of using beams with channel and I section in three classes of seismically compact, seismically non-compact, and slender section according to width-to-thickness ratio on the behavior of the connection was investigated under monotonic and cyclic loading. Modeling was performed by ABAQUS and verified by the results of an experimental specimen. The findings indicated that using I and channel section instead of angle section reduces the amount of welding materials as well as easing the installation procedure. However, it has no significant effect on the ultimate strength and ductility of the connection. Furthermore, if the beam section is seismically compact, this form is considered as a special moment frame that has a rotation capacity up to 0.04 radians without any reduction in connection moment resistance.
Seyed Morteza Kazemi,Mohammad Reza Sohrabi,Hasan Haji-Kazemi 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.29 No.3
Researchers have been long studying new building implementation methods to improve the quality of construction, reduce the time of assembly, and increase productivity. One of these methods is the use of modular pre-fabricated structural forms that are composed of a beam, column, short column, pyramidal end block, and connection plates. In this study, a new geometry for the pyramidal end block was proposed that helps facilitate the assembly procedure. Since the proposed configuration affects the performance of this form of connection, its behavior was evaluated using finite element method. For this purpose, the connection was modeled in ABAQUS and then validated by comparing the outputs with experimental results. The research proceeded through analyzing 16 specimens under monotonic and cyclic loading. The results indicated that using the pyramidal end block not only makes the assembly process easier but also reduces the out-of-plane displacement of the short column webs and the vertical displacement of beam end. By choosing appropriate section properties for column and beam, the connection can bear a rotation up to 0.01 radians within its inelastic region and a total of 0.04 radians without any significant reduction in its bearing capacity.
Design equations for prefabricated steel moment connections
Seyed Morteza Kazemi,Mohammad Reza Sohrabi,Hasan Haji Kazemi 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.3
Recently, modular prefabricated steel moment connections have been widely studied by several researchers. These connections are made of tubular columns that are ended to horizontal plates at both sides, an inter-story short column, and truss beams that are joined to the connecting plates using top and bottom plates. In this study, a series of equations have been developed and presented for designing each component of this type of connection. Then, to verify the proposed equations, the connection was modeled in ABAQUS and then the results extracted from the equations and modeling were compared. The findings indicated that the proposed equations have the required accuracy.
Soroush Baradaran,Morteza Sohrabi,Parsia Moghimpour Bijani,Sayed Javid Royaee 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.27 No.-
Co-Aromatization of isobutane and propane over H-ZSM-5 and Zn/ZSM-5 catalysts prepared by differentcrystallization time ranging from 24 h to 96 h at 180 8C was studied. The samples were characterized viaXRD, BET, SEM and NH3-TPD. A maximum for crystallinity was observed at 72 h with 98% and Acidityalong with crystal size increased with time. Performance tests in a fixed bed reactor at 550 8C showedthat catalytic activity increased with crystallization time while the aromatics selectivity increased withcrystallinity. The results also indicated that conversion of propane in the presence of isobutane wasdramatically lower than individual propane test.
Sayed Javid Royaee,Morteza Sohrabi,Narges Fallah 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.11
The degradation of phenol was investigated in a continuous flow impinging streams system. In the first step, statistical experimental designs were used to optimize the process of phenol degradation in a photo-impinging streams reactor. The more important factors affecting phenol degradation (p<0.05) were screened by a two-level Plackett-Burman design. Four of the latter parameters, namely phenol concentration, catalyst loading, pH and slurry flow rate,were selected for final process optimization, applying central composite design (CCD). The predicted data showed that the maximum removal efficiency of phenol (99%) could be obtained under the optimum operating conditions (phenol concentration=50 mg l−1, catalyst loading=2.1 g l−1, pH 6.2 and slurry flow rate=550ml min−1). These predicted values were then verified by certain validating experiments. A good correlation was observed between the predicted data and those determined by the experimental study. This may confirm the validity of the statistical optimum strategy. Finally,continuous degradation of phenol was performed, and the results indicated a higher efficiency and an increased performance capability of the present reactor in comparison with the conventional processes.