Cold-Formed Steel (CFS) sections provide many design and construction sophistications including lightweight and high strength-to-weight ratio. The SupaCee section was introduced to CFS industry due ...to its cost effectiveness, enhanced strength, better structural performance and high stiffness. Introduction of SupaCee sections lead to investigations of web crippling, flexural and shear behaviour of the sections. However, structural behaviour of SupaCee sections with web openings has not been addressed to date. Hence, this study intends to analyse the shear behaviour of SupaCee sections with web openings. Previous shear test results of SupaCee sections and Lipped Channel Beam (LCB) sections with openings were validated with developed FE models. An extensive parametric study was accomplished considering various geometric parameters such as depth, yield strength, thickness and web opening ratios. Since the results of the detailed study determined that existing design equations were over conservative, new design equations with reduction factor were proposed to predict the ultimate shear capacity of SupaCee sections with web openings. Moreover, the shear capacities of SupaCee sections were compared with shear capacities of similar dimensioned LCB sections. A web opening ratio of 0.2 is recommended, considering the ability to regain the shear capacity of plain LCB sections, as well as the availability of web openings in order to accommodate the services.
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•Investigated shear behaviour of SupaCee sections with circular openings•Finite element models considering structural and geometric defects were developed and validated to eliminate test set-up errors•Shear reduction factor equations for SupaCee section with openings are not available in the design standards•Reduction factors for circular openings were proposed based on the area and depth ratio methods•Shear strength of SupaCee sections and Lipped Channel Beams were compared for their similar sections
This paper reviews the research advancements and design practices related to the structural web crippling response of lipped Cold-Formed (CF) carbon steel, stainless steel, and aluminium channels ...with web perforations. The web crippling response differs among each material based on the non-linear stress-strain characteristics and degree of strain hardening. Therefore, the reduction in the web crippling strength of web-perforated CF channel sections made of different materials may not be equivalent. The research activities surrounding the web crippling response of CF channels with and without web openings were reviewed initially. Despite the limited design provisions given in the international specifications for the web crippling design of lipped CF channels with web openings, web crippling studies conducted across the world have developed suitable design equations in the form of reduction factors. Past research studies have substantially captured the web crippling response of carbon steel channels with web openings while that of stainless steel and aluminium are limited, as identified in this paper. Lastly, numerical models were developed for simulating the web crippling behaviour of lipped CF carbon steel, stainless steel, and aluminium channels with web opening and validated with past experimental data, with a view for developing unified design guidelines.
Multisystem inflammatory syndrome in children (MIS-C), a sequela of severe acute respiratory syndrome coronavirus-2 infection (SARS-CoV2), has been progressively reported worldwide, with cardiac ...involvement being a frequent presentation. Although the clinical and immunological characteristics of MIS-C with and without cardiac involvement have been described, the immunological differences between cardiac and non-cardiac MIS-C are not well understood.
The levels of type 1, type 2, type 17, other proinflammatory cytokines and CC chemokines and CXC chemokines were measured using the Magpix multiplex cytokine assay system in MIS-C children with MIS-C cardiac (MIS-C (C) (
= 88)) and MIS-C non-cardiac (MIS-C (NC) (
= 64)) abnormalities.
MIS-C children with cardiac manifestations presented with significantly increased levels of cytokines such as IFN-γ, IL-2, TNFα, IL-5, IL-1α, IL-1β, IL-6, IL-10 and IL-12p70 and chemokines such as CCL2, CCL3, CCL11 and CXCL10 in comparison to MIS-C children without cardiac manifestations. Clustering analysis revealed that cytokines and chemokines could clearly distinguish MIS-C children with and without cardiac manifestations. In addition, these responses significantly diminished and normalized 9 months after treatment.
This is one of the first studies characterizing and differentiating systemic inflammation in MIS-C with and without cardiac involvement from a low- and middle-income country (LMIC). Our study contributes to the existing body of evidence and advances our knowledge of the immunopathogenesis of MIS-C in children.
Cold-Formed Steel (CFS) sections are extensively used in structural engineering applications replacing the conventional hot-rolled sections due to their inherent advantages. Web openings are ...generally placed in CFS floor joists and bearers to accommodate the building services, which leads the reduction of floor height. The web openings significantly influence the shear behaviour and reduce the shear capacity. However, very limited research studies have been conducted on hollow flange CFS beams with web openings under shear load. Therefore, this study presents a detailed Finite Element (FE) investigation of the shear behaviour of CFS doubly symmetric Rectangular Hollow Flange Beams (RHFBs) with unreinforced circular web openings. Non-linear FE models were created and validated using the laboratory shear test results. A detailed parametric study was then carried out by extending the validated FE models for doubly symmetric RHFBs with circular web openings. In total,126 FE models were investigated with different geometric parameters including section depth, thickness, material strength and web opening sizes to observe their behaviour on shear strength. The results showed that the existing shear strength design equations are either unsafe or conservative for doubly symmetric RHFBs with unreinforced circular web openings. Therefore, new Direct Strength Method (DSM) based shear design rules are proposed to estimate the shear strength of doubly symmetric RHFBs with unreinforced circular web openings in conjunction with proposed shear reduction factor (qs).
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•Investigated shear behaviour of doubly symmetric rectangular hollow flange beam with circular openings.•Finite element models considering imperfections were developed and validated to eliminate test set-up errors.•Shear design equations for doubly symmetric rectangular hollow flange beam with openings are not available in standards.•Reduction factors for circular openings were proposed based on the area and depth ratio methods.•DSM equation was proposed for doubly symmetric rectangular hollow flange beam.
The modular construction industry often seeks cost-effective, high-performing, and longer-span members in buildings to ensure efficiency and quality. Accordingly, the idea of built-up sections was ...brought into gain numerous benefits including higher structural capacity, improved torsional rigidity, and increased stiffness. While limited research studies have been carried out to study the structural performances of built-up sections, few innovative section profiles have been developed in the industry considering the structural benefits, including improved stiffness. Hence, the application of newly developed built-up sections could enhance the employment of built-up sections in the industry. On that note, this research is focused on the flexural behaviour of optimised section profiles named the LCB-benchmark (Lipped Channel Beam), the optimised-LCB, folded-flange and the super-sigma sections. In addition, different materials, namely cold-formed carbon steel (CFS), cold-formed (CF) aluminium and CF stainless steel, were considered for built-up sections, in order to provide recommendations based on their flexural performances. Numerical analysis was carried out on single sections as well as on built-up sections to the developed parametric plan after the successful validation of experimental studies. The results were compared for single and built-up sections. Finally, based on the comparisons, the folded-flange built-up section is recommended for all three materials as it displayed the highest bending capacity, and the capacity enhancement compared to the corresponding single section was a minimum of 131%.
High-strength Cold-Formed Steel (CFS) members are widely adopted as structural members in building structures due to its higher ultimate capacity. The flexural members are often subjected to ...concentrated transverse loads which may leads to buckling instabilities including web crippling. However, there is no appropriate design rules and studies are available to estimate the web crippling strength of high-strength CFS members. Hence, this paper presents a detailed numerical investigation on high-strength CFS unlipped channel sections subjected to End-One-Flange (EOF) loading condition with nominal yield strengths of 700 MPa, 900 MPa and 1000 MPa. For numerical simulation study, non-linear Finite Element (FE) models were developed and validated with the experimental results followed by an extensive parametric study using ABAQUS. In total, 243 FE models were developed with different geometric and material parameters including section thickness, material strength, web slenderness ratio, inside bent radius to thickness ratio and bearing length to thickness ratio. The ultimate web crippling strength results were compared with the available design guidelines to check their suitability and accuracy in terms of strength prediction. Then, new design rules to predict the web crippling capacity of high-strength CFS unlipped channel section under EOF condition based on unified and Direct Strength Method (DSM) approaches were proposed.
•Investigated shear behaviour of doubly symmetric RHFB with circular edge-stiffened openings.•Shear design equations with edge-stiffened openings are not available in design standards.•A reduction ...factor of doubly symmetric RHFB with circular edge-stiffened openings was proposed.•DSM was proposed for doubly symmetric RHFB without openings and are checked with reduction factor.•The optimum edge-stiffener length for doubly symmetric RHFB was proposed as 15 mm.
Cold-Formed Steel (CFS) sections are evolved through the last two decades compromising various aspects of construction needs. Doubly symmetric Rectangular Hollow Flange Beam (RHFB) is one of the innovative CFS sections, which was introduced to eliminate the drawbacks of conventional open CFS sections such as prone to complex buckling and torsional effects. Edge-stiffened web holes are recently recommended and available for extensive usage in the floor beams. Even though previous studies conducted researches on various kinds of stiffeners, there is no definite design equation or findings that were presented on shear behaviour. Therefore, this study focuses on the effect of edge-stiffened circular web openings on the shear capacity of doubly symmetric RHFB. Non-linear numerical models were developed using the ABAQUS software package for validation purposes and then comprehensive parametric studies were carried out for doubly symmetric RHFB with edge-stiffened openings. A total of 558 models consisting of edge-stiffeners, un-stiffened openings and plain webs were analysed in this study. Parametric results of with edge stiffeners exhibited shear capacity increment (1–90%) compared to unstiffened web openings. Hence, new design equations were proposed in the form of reduction factor and based on Direct Strength Method (DSM). Finally, optimum edge-stiffener length of 15 mm was recommended regardless of web opening size.
Abstract
Background
Multisystem inflammatory syndrome in children (MIS-C) presents with inflammation and pathology of multiple organs in the pediatric population in the weeks following severe acute ...respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
Methods
We characterized the SARS-CoV-2 antigen–specific cytokine and chemokine responses in children with MIS-C, coronavirus disease 2019 (COVID-19), and other infectious diseases.
Results
MIS-C is characterized by elevated levels of type 1 (interferon-γ, interleukin IL 2), type 2 (IL-4, IL-13), type 17 (IL-17), and other proinflammatory cytokines (IL-1α, IL-6, IL-12p70, IL-18, and granulocyte-macrophage colony-stimulating factor) in comparison to COVID-19 and other infectious diseases following stimulation with SARS-CoV-2–specific antigens. Similarly, upon SARS-CoV-2 antigen stimulation, CCL2, CCL3, and CXCL10 chemokines were significantly elevated in children with MIS-C in comparison to the other 2 groups. Principal component analysis based on these cytokines and chemokines could clearly distinguish MIS-C from both COVID-19 and other infections. In addition, these responses were significantly diminished and normalized 6–9 months after recovery.
Conclusions
Our data suggest that MIS-C is characterized by an enhanced production of cytokines and chemokines that may be associated with disease pathogenesis.
Industrialization and urbanization demand high amount of water consumption, which contributes to their polluted condition. Thus, there is a need to develop a sustainable wastewater remediation ...technique in order to provide sustainable use of clean water for future generations without ramifications to the economic sectors. The newly synthesized TiO2-SiO2 photocatalyst was used to remediate Methylene Blue contaminated aqueous solution in the presence of active chlorine species. The doping of SiO2 into TiO2 enhanced the removal rate of Methylene Blue dye from the solution by increasing the surface area, thermal stability and surface acidity of the TiO2. The active chlorine species further enhanced the removal rate of Methylene Blue dye from the solution by contributing more reactive species, chlorine radicals, which broke down the dye molecules. The experiments were conducted via Taguchi analysis. The findings show that combining TiO2, SiO2 and active chlorine species enhanced the removal percentage of Methylene Blue dye compared to using TiO2 alone by 70%. About 70% of 50ppm Methylene Blue was degraded by 1 g of TiO2-SiO2 in the presence of 0.3 ppm Ca(OCl)2 under 9 Watts solar irradiation within 3 hours. The enhanced dye removal method brings photocatalysis a step closer to sustainable wastewater remediation methods.
Cold-Formed (CF) structural members have become important in conventional and emerging modular building constructions. However, point loads can result in web crippling failure of floor joists, ...purlins and decks. Due to their enhanced structural, aesthetic and resistive properties, CF aluminium and CF stainless-steel beams are used as an alternative solution to CF carbon steel beams. This paper ultimately investigates the web crippling behaviour of lipped channel beams under Interior Two-Flange (ITF) loading conditions. Since there is no unified approach is available for web crippling behaviour of various materials, this study focused on it. Three structural materials were considered as part of the study: carbon steel, aluminium and stainless-steel. Available experimental studies were used to validate Finite Element (FE) models, before an extensive parametric study (378 FE models) was carried out. Commercially available lipped channels with relatively lower web depth were considered to examine the web crippling behaviour under lower slenderness. Current design codes showed inaccurate prediction up to 15% against the results. This paper ultimately proposes new unified design guidelines for predicting the web crippling capacity of CF carbon steel, CF aluminium and CF stainless-steel lipped channel beams under ITF loading conditions.
•ITF load case web crippling strength of cold-formed carbon steel, stainless steel, and aluminium channels were investigated.•Finite element models were developed and validated with test results.•The parametric analysis included 378 FE models and three common yield strengths.•Proposed unified design approach incorporating yield strength and elastic modulus strength factors.•The proposed design approach showed good accuracy against the parametric study results.
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