Structural behaviour of tapered concrete-filled steel composite (TCFSC) columns subjected to eccentric loading

Alireza Bahrami,Wan Hamidon Wan Badaruzzaman,Siti Aminah Osman 사단법인 한국계산역학회 2012 Computers and Concrete, An International Journal Vol.9 No.6

This paper deals with the structural behaviour of tapered concrete-filled steel composite (TCFSC) columns under eccentric loading. Finite element software LUSAS is used to perform the nonlinear analyses to predict the structural behaviour of the columns. Results from the finite element modelling and existing experimental test are compared to verify the accuracy of the modelling. It is demonstrated that they correlate reasonably well with each other; therefore, the proposed finite element modelling is absolutely accurate to predict the structural behaviour of the columns. Nonlinear analyses are carried out to investigate the behaviour of the columns where the main parameters are: (1) tapered angle (from 0o to 2.75o); (2) steel wall thickness (from 3 mm to 4 mm); (3) load eccentricity (15 mm and 30 mm); (4) L/H ratio (from 10.67 to 17.33); (5) concrete compressive strength (from 30 MPa to 60 MPa); (6) steel yield stress (from 250 MPa to 495 MPa). Results are depicted in the form of load versus mid-height deflection plots. Effects of various tapered angles, steel wall thicknesses, and L/H ratios on the ultimate load capacity, ductility and stiffness of the columns are studied. Effects of different load eccentricities, concrete compressive strengths and steel yield stresses on the ultimate load capacity of the columns are also examined. It is concluded from the study that the parameters considerably influence the structural behaviour of the columns.

Nonlinear analysis of concrete-filled steel composite columns subjected to axial loading

Bahrami, Alireza,Badaruzzamana, Wan Hamidon Wan,Osmanb, Siti Aminah Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.3

This paper investigates the nonlinear analysis of concrete-filled steel composite columns subjected to axial loading to predict the ultimate load capacity and behaviour of the columns. Finite element software LUSAS is used to conduct the nonlinear analyses. The accuracy of the finite element modelling is verified by comparing the result with the corresponding experimental result reported by other researchers. Nonlinear analyses are done to study and develop different shapes and number of cold-formed steel sheeting stiffeners with various thicknesses of cold-formed steel sheets. Effects of the parameters on the ultimate axial load capacity and ductility of the concrete-filled steel composite columns are examined. Effects of variables such as concrete compressive strength $f_c$ and cold-formed steel sheet yield stress $f_{yp}$ on the ultimate axial load capacity of the columns are also investigated. The results are shown in the form of axial load-normalized axial shortening plots. It is concluded from the study that the ultimate axial load capacity and behaviour of the concrete-filled steel composite columns can be accurately predicted by the proposed finite element modelling. Results in this study demonstrate that the ultimate axial load capacity and ductility of the columns are affected with various thicknesses of steel sheets and different shapes and number of stiffeners. Also, compressive strength $f_c$ of the concrete and yield stress $f_{yp}$ of the cold-formed steel sheet influence the performance of the columns significantly.

Nonlinear analysis of concrete-filled steel composite columns subjected to axial loading

Alireza Bahrami,Wan Hamidon Wan Badaruzzaman,Siti Aminah Osman 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.3

This paper investigates the nonlinear analysis of concrete-filled steel composite columns subjected to axial loading to predict the ultimate load capacity and behaviour of the columns. Finite element software LUSAS is used to conduct the nonlinear analyses. The accuracy of the finite element modelling is verified by comparing the result with the corresponding experimental result reported by other researchers. Nonlinear analyses are done to study and develop different shapes and number of cold-formed steel sheeting stiffeners with various thicknesses of cold-formed steel sheets. Effects of the parameters on the ultimate axial load capacity and ductility of the concrete-filled steel composite columns are examined. Effects of variables such as concrete compressive strength f_c and cold-formed steel sheet yield stress f_yp on the ultimate axial load capacity of the columns are also investigated. The results are shown in the form of axial load-normalized axial shortening plots. It is concluded from the study that the ultimate axial load capacity and behaviour of the concrete-filled steel composite columns can be accurately predicted by the proposed finite element modelling. Results in this study demonstrate that the ultimate axial load capacity and ductility of the columns are affected with various thicknesses of steel sheets and different shapes and number of stiffeners. Also, compressive strength f_c of the concrete and yield stress f_yp of the cold-formed steel sheet influence the performance of the columns significantly.

Dietary Intake of Polyphenols and the Risk of Breast Cancer: a Case-Control Study

Bahrami Alireza,Makiabadi Elham,Jalali Saba,Heidari Zeinab,Assadi Mojan,Rashidkhani Bahram 한국임상영양학회 2021 Clinical Nutrition Research Vol.10 No.4

Despite mounting evidence that dietary polyphenols might have a protective role against the risk of breast cancer (BC), few studies have assessed the relationship between intake of polyphenol classes and subclasses with BC. Thus, we examined the relationship between dietary polyphenol classes and individual polyphenol subclasses and the risk of BC. Overall, 134 newly diagnosed BC patients and 267 healthy hospitalized controls were studied. Dietary intake was assessed using a validated 168-item food frequency questionnaire (FFQ). To estimate dietary intake of polyphenols, polyphenol content (flavonoids, lignans, stilbenes and phenolic acids) of 80 food items were derived from an updated version of the phenol explorer database containing information on the effects of food processing on polyphenol content. The dietary polyphenol intake was calculated by matching the subjects' food consumption data with our polyphenol content database. Multivariate logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Controls had higher intake of total polyphenol (marginally significant; p = 0.07), hydroxycinnamic acid (marginally significant; p = 0.05) and lignan (p = 0.01). After adjusting for potential confounders, high consumption of lignans (highest vs. lowest tertile: OR, 0.51; 95% CI, 0.26–0.97; p for trend = 0.04) associated with decreased risk of BC. There was no significant relationship between intake of other polyphenols and risk of BC. Our findings suggest that high lignan intake is associated with a reduced risk of BC.

Mechanical and thermo-mechanical properties of short carbon fiber reinforced polypropylene composites using exfoliated graphene nanoplatelets coating

Alireza Ashori,Saman Menbari,Reza Bahrami 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.38 No.-

This work reports an improvement in the mechanical and thermo-mechanical properties of short carbonfiber (SCF)/polypropylene (PP) composite, resulting from coating of the SCFs with exfoliated graphenenanoplatelets (xGnPs). Firstly, the xGnPs were coated on the SCFs surface by a simple physical absorptionmethod, and then the composites were manufactured by melt blending and hot-press processing. Theamount of SCFs was kept constant at 15 wt% and the amount of xGnP was varied up to 3 wt%. Results oftensile and impact measurements indicated that, for the xGnP–SCF/PP composite, maximum tensilestrength, tensile modulus and impact strength were 43.4 MPa, 1.052 GPa, and 38.1 J/m, respectively,corresponding to 13.6%, 41.7%, and 7.3% enhancement compared to the untreated SCF/PP composite. Inaddition, the results of dynamic mechanical thermal analyses indicated enhancement in storagemodulus and damping capacity for the treated samples; however, no significant difference was observedin the glass transition temperature. The xGnP–SCF/PP interface adhesion enhancement was clearlyshown by scanning electron microscopy (SEM) images of the tensile failure surfaces. Finally, the optimalxGnP content for effectively improving the overall composite mechanical and thermo-mechanicalperformance was found to be 1 wt%.

Evaluation of the cell viability and antimicrobial effects of orthodontic bands coated with silver or zinc oxide nanoparticles: An in vitro study

Rashin Bahrami,Maryam Pourhajibagher,Alireza Badiei,Reza Masaeli,Behrad Tanbakuchi 대한치과교정학회 2023 대한치과교정학회지 Vol.53 No.1

Objective: We aimed to evaluate the cell viability and antimicrobial effects of orthodontic bands coated with silver or zinc oxide nanoparticles (nano-Ag and nano-ZnO, respectively). Methods: In this experimental study, 30 orthodontic bands were divided into three groups (n = 10 each): control (uncoated band), Ag (silver-coated band), and ZnO (zinc oxide-coated band). The electrostatic spray-assisted vapor deposition method was used to coat orthodontic bands with nano-Ag or nano-ZnO. The biofilm inhibition test was used to assess the antimicrobial effectiveness of nano-Ag and nano-ZnO against Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans. Biocompatibility tests were conducted using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. The groups were compared using one-way analysis of variance with a post-hoc test. Results: The Ag group showed a significantly higher reduction in the number of L. acidophilus, C. albicans, and S. mutans colonies than the ZnO group (p = 0.015, 0.003, and 0.005, respectively). Compared with the control group, the Ag group showed a 2-log10 reduction in all the microorganisms' replication ability, but only S. mutants showed a 2-log10 reduction in replication ability in the ZnO group. The lowest mean cell viability was observed in the Ag group, but the difference between the groups was insignificant (p > 0.05). Conclusions: Coating orthodontic bands with nano-ZnO or nano-Ag induced antimicrobial effects against oral pathogens. Among the nanoparticles, nano-Ag showed the best antimicrobial activity and nano-ZnO showed the highest biocompatibility.

Identification and Prioritization of the Driving Factors of Labor Productivity in the Melli Bank: Iranian Scenario

Mostafa Bahrami,Mahdi Salehi,Mohsen Akbarzadeh,Alireza Morsali 한국유통과학회 2013 The Journal of Industrial Distribution & Business( Vol.4 No.1

Purpose - Labor productivity is extremely important to the profitability and competitive advantage of organizations that provide services to customers, such as banks. This study investigates the factors driving labor productivity in Iran’s Melli Bank. Research design, data, methodology - Five managerial, psychosocial, cultural, and individual factors are identified and their relative importance for labor productivity prioritized using AHP. The required data are then collected through a questionnaire designed for a pairwise comparison of the driving factors of labor productivity and their subcategories. Results - The study outcomes reveal that the managerial and individual factors are the most important. Specifically, the most important factors in increasing labor productivity in the branches of Melli Bank are having a competent supervisor, promotion opportunities, fair working conditions, conscientiousness, the right tools, and a correspondence between skills and work. Conclusions - Implementing AHP using Expert Choice software revealed that, among the driving factors of labor productivity (i.e., managerial, psychosocial, cultural, environmental, and personal), managerial factors were considered the most important by the respondents.

A review on the pharmacokinetic properties and toxicity considerations for chloroquine and hydroxychloroquine to potentially treat coronavirus patients

Askarian Fatemeh,Firoozi Zahra,Ebadollahi-Natanzi Alireza,Bahrami Solmaz,Rahimi Hamid-Reza 한국독성학회 2022 Toxicological Research Vol.38 No.2

The SARS-CoV-2 virus, caused a novel emerged coronavirus disease, is growing rapidly worldwide. Few studies have evaluated the efficacy and safety of Chloroquine (CQ), an old antimalarial drug, and Hydroxychloroquine (HCQ) in the treatment of COVID-19 infection. HCQ is derived from CQ by adding a hydroxyl group into it and is a less toxic derivative of CQ for the treatment of COVID-19 infection because it is more soluble. This article summarizes pharmacokinetic properties and toxicity considerations for CQ and HCQ, drug interactions, and their potential efficacy against COVID-19. The authors also look at the biochemistry changes and clinical uses of CQ and HCQ, and supportive treatments following toxicity occurs. It was believed that CQ and HCQ may provide few benefits to COVID-19 patients. A number of factors should be considered to keep the drug safe, such as dose, in vivo animal toxicological findings, and gathering of metabolites in plasma and/or tissues. The main conclusion of this review is that CQ and HCQ with considered to their ADMET properties has major shortcomings and fully irresponsible.