Experimental study of the influence of friction at the supports on longitudinal shear resistance of composite slabs

Abstract The aim of this work is to evaluate the behavior and strength of composite slabs considering the influence of the friction at the sheeting-concrete interface in the region of the support. Results from tests conducted in the Structural Engineering Department of Federal University of Minas Gerais (UFMG) were used. A Steel Deck 60 system was considered, which consists of a trapezoidal profile with “V” shaped embossments. Deflections, end slips and strains of the steel decks were measured, allowing for the analysis of the behavior of the composite slab system and for the determination of its failure mode. The influence of friction of the region of support in the longitudinal shear resistance was evaluated through the partial shear connection method, which also allowed for establishing criteria and determination of analytical expressions for calculating the ultimate load. Comparative analyses reveal that the influence of the friction of the region of support in the shear-bond resistance is more significant in composite slabs with short shear spans. Design expressions which incorporate friction will also be presented. Their application have demonstrated the efficiency of the method for evaluating the longitudinal shear resistance

Experimental study of the influence of friction at the supports on longitudinal shear resistance of composite slabs

<div><p>Abstract The aim of this work is to evaluate the behavior and strength of composite slabs considering the influence of the friction at the sheeting-concrete interface in the region of the support. Results from tests conducted in the Structural Engineering Department of Federal University of Minas Gerais (UFMG) were used. A Steel Deck 60 system was considered, which consists of a trapezoidal profile with “V” shaped embossments. Deflections, end slips and strains of the steel decks were measured, allowing for the analysis of the behavior of the composite slab system and for the determination of its failure mode. The influence of friction of the region of support in the longitudinal shear resistance was evaluated through the partial shear connection method, which also allowed for establishing criteria and determination of analytical expressions for calculating the ultimate load. Comparative analyses reveal that the influence of the friction of the region of support in the shear-bond resistance is more significant in composite slabs with short shear spans. Design expressions which incorporate friction will also be presented. Their application have demonstrated the efficiency of the method for evaluating the longitudinal shear resistance.</p></div

MCM-41 silica effect on gel polymer electrolytes based on thermoplastic polyurethane

Polymer electrolytes were prepared from thermoplastic polyurethane with addition of mixture of Nethyl( methylether)-N-methylpyrrolidinium trifluoromethanesulfonimide (PYRA12O1TFSI) ionic liquid, lithium bis(trifluoromethanesulfoneimide) salt and propylene carbonate. MCM-41 mesoporous silica was added in proportions ranging from 5 to 20 wt.% with respect to TPU. The electrolytes were characterized by thermogravimetric analysis, differential scanning calorimetry, linear voltammetry and impedance spectroscopy. The MCM-41 addition to the system was found to improve the electrochemical stability of the membranes and to reduce the gel electrolyte/metallic Li interfacial resistance. The filler influence on the ion transport processes was discussed according to results obtained by equivalent circuit fitting of impedance spectra

Biliquid Supercapacitors: a Simple and New Strategy to Enhance Energy Density in Asymmetric/Hybrid Devices

A novel strategy for the development of high energy density supercapacitors (SC) is explored. The new devices contain two electrolytes that are different in nature, an aqueous electrolyte in one half-cell and an ionic liquid in the other. These systems, referred to as biliquid SCs, make it possible to combine the best electrode/electrolyte in terms of individual electrode capacitance and cathodic/anodic stability limits. Furthermore, other asymmetries that combine different electrodes, electrolytes and storage mechanisms can be incorporated. Synchronous cyclic chronopotenciometry was used to monitor the performance of these novel complex systems. It is expected that this approach will help scientists working in this field to develop new devices that overcome the energy density limitations of current SCs, thereby extending the scope of their application.The authors would like to thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) − Brazil for the financial support (PVE 2014, process number 400714/2014-0). Paulo Fernando R. Ortega also acknowledges CNPq for the received scholarships. Financial support from Ministerio de Economía, Industria y Competitividad (project MAT2016-77114-R) and Principado de Asturias (Fondo Europeo de Desarrollo Regional, GRUPIN 14-118).Peer reviewe

High value activated carbons from waste polystyrene foams

Activated carbons (AC) with excellent textural properties have been obtained for the first time from waste polystyrene foam (PF), without any previous treatment, following a simple and conventional two-step procedure (formation of char followed by chemical activation). Even considering that the PF is not a graphitizable material, the best AC produced from this precursor has a very high BET surface area larger than 2700 m2 g−1 and a pore volume of 1.2 cm2 g−1, with a significant contribution of small mesopores. As a consequence, this AC reveals a surprising capacity to adsorption of relatively large molecules and a high specific capacitance when applied as a supercapacitor electrode. The maximum amount of adsorbed methylene blue obtained by batch equilibrium experiments are greater than 1 g g−1. In the context of the technical difficulties and low economic return of the reuse and recycling of waste PF, this work offers a strategic destination for this environmentally unfriendly residue.The authors would like to thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) – Brazil for the financial support (PVE 2014, process number 400714/2014-0). Fabiano G. F. de Paula and Paulo F. R. Ortega also acknowledge CAPES and CNPq for the received scholarships, respectively. Financial support from Ministerio de Economía, Industria y Competitividad (project MAT2016-77114-R) and Principado de Asturias (Fondo Europeo de Desarrollo Regional (GRUPIN 14-118).Peer reviewe