Numerical modelling of the reinforced concrete beam shear failure

Shear failure of reinforced concrete members is a complex process, which depends on a huge number of different factors. It is less investigated compared to other types of failure. Modern numerical methods, including finite-element method, allow predicting complex behavior of different structures when loaded. This article deals with the detailed nonlinear analysis of the shear failure of the reinforced concrete beam, using Drucker-Prager yield criterion. The results generated based on the finite-element model, developed in ANSYS software, were compared to the results of a laboratory experiment. In addition, the main advantages and disadvantages of this approach were described. © Published under licence by IOP Publishing Ltd

Identification of high performance solvents for the sustainable processing of graphene

Nanomaterials have many advanced applications, from bio-medicine to flexible electronics to energy storage, and the broad interest in graphene-based materials and devices means that high annual tonnages will be required to meet this demand. However, manufacturing at the required scale remains unfeasible until economic and environmental obstacles are resolved. Liquid exfoliation of graphite is the preferred scalable method to prepare large quantities of good quality graphene, but only low concentrations are achieved and the solvents habitually employed are toxic. Furthermore, good dispersions of nanomaterials in organic solvents are crucial for the synthesis of many types of nanocomposites. To address the performance and safety issues of solvent use, a bespoke approach to solvent selection was developed and the renewable solvent Cyrene was identified as having excellent properties. Graphene dispersions in Cyrene were found to be an order of magnitude more concentrated than those achieved in N-methylpyrrolidinone (NMP). Key attributes to this success are optimum solvent polarity, and importantly a high viscosity. We report the role of viscosity as crucial for the creation of larger and less defective graphene flakes. These findings can equally be applied to the dispersion of other layered bi-dimensional materials, where alternative solvent options could be used as drop-in replacements for established processes without disruption or the need to use specialized equipment. Thus, the discovery of a benign yet high performance graphene processing solvent enhances the efficiency, sustainability and commercial potential of this ever-growing field, particularly in the area of bulk material processing for large volume applications

Controllable production of liquid and solid biofuels by doping-free, microwave-assisted, pressurised pyrolysis of hemicellulose

Batch, pressurised microwave-assisted pyrolysis of hemicellulose in the absence of any external microwave absorber was found to be a promising route for the production of bio-based chemicals and biofuels. The experiments were conducted in a 10 mL batch reactor using a fixed power of 200 W employing different initial masses of xylan (0.1–0.7 g) for a maximum time, temperature and pressure of 10 min, 250 °C and 200 psi, respectively. The gas, bio-oil and solid (char) yields varied by 16–40%, 2–21% and 40–82%, respectively. Char production is preferential using a low amount of xylan (<0.25 g), while bio-oil production is favoured using a high amount of xylan (0.25–0.7 g). The effect of the sample mass is accounted for by the different physical state of the volatiles released during pyrolysis depending on the pressure attained during the experiment. This permits the process to be easily customised for the selective production of liquid (bio-oil) or solid (bio-char). Regarding the bio-oil, it is composed of a mixture of platform chemicals such as aldehydes, alkenes, phenols, polyaromatic hydrocarbons (PAHC), cyclic ketones and furans, with the composition varying depending on the initial mass of xylan. The char had a higher proportion of C together with a lower proportion of O than the original feedstock. Energy efficiencies of 100 and 26% were achieved for char and bio-oil production, respectively; thus leading to an increase in the HHV of the products (with respect to the original feedstock) of 52% for char and 19% for bio-oil

A new perspective in bio-refining : Levoglucosenone and cleaner lignin from waste biorefinery hydrolysis lignin by selective conversion of residual saccharides

An unexpected opportunity is reported to improve the sustainability of biorefineries whereby 8 wt% levoglucosenone (LGE) can be derived from unconverted saccharides in a lignin-rich biorefinery waste stream in a highly selective fashion (>90%). Additionally, in the process a purer lignin is obtained which can be used for further processing or materials applications. LGE is a valuable and versatile product with a plethora of applications

Передвижные морские буровые платформы для поиска месторождений нефти и газа. Обзор

A Jack-Up platform can float and be transported, it can be elevated when it arrives on location and its legs will rest on the sea bed. After an appropriate and rigorous site assessment the unit will be ready for operation. Due to the compliant characteristics of the structural system difficult challenges must be overcome by designers and operators. Generally, these challenges are more complex than most offshore structures and the later section in this chapter related to the management of hazards endorses this comment. This article is an overview of the main characteristics of these mobile units. A modern Jack-Up can weigh up to 20,000 tonnes and be capable of operating in 150 m of water in a very harsh ocean environment. Jack-Up platforms are designed and constructed to satisfy the rules of classification societies and classification is a comprehensive verification procedure. In this respect they may be regarded as mobile units together with ships and other marine structures. The main structural features are associated with the hull and the legs and foundation. However, separate sections for Jack-Up structural design and foundation design have been included in the Jack-Up chapter. Transportation is a critical stage when the unit can become unstable, but elevating the structure and the process of jacking can also be problematic. Transportation has been considered as a separate section in this chapter and the examples of accidents as case studies demonstrate the dangers associated with the critical stages of operation. Consideration has been given to the use of high strength steel in this review, but sections related to Fatigue and to Fracture Mechanics have been provided separately in the Jack-Up chapter. The section related to Marine Warranty Survey aspects brings together many of the features of Jack-Up operations and the potential of Jack-Up risk and reliability studies for risk assessment of various operating stages has been explored in the Reliability section within this chapter.Передвижная морская буровая платформа может плавать и перевозиться, ее можно поднимать, когда она прибывает на место, и ее ноги будут опираться на морское дно. После тщательного обследования конструкции и площадки установки, соответствующей и строгой оценки площадки буровая платформа готова к работе. Конструкторы и монтажники должны преодолеть и разрешить все возникающие проблемы установки буровой платформы. В этой статье рассмотрены основные характеристики этих передвижных конструкций. Вес современных передвижных морских буровых платформ достигает 20 000 тонн и они способны работать на глубинах до 150 м в суровых океанских условиях. Морские буровые платформы проектируются и строятся в соответствии со строгими положениями норм, а комплексная процедура проверки их соответствия нормативным требованиям является сложной задачей. В этом отношении они могут быть отнесены к категории морских судов. Основными конструкциями морских буровых платформ являются корпус, опоры и основание. Наиболее опасной ситуацией является передвижение морской буровой платформы, когда могут нарушиться требования общей устойчивости конструкции, однако в процессе ее подъема также могут возникнуть опасные ситуации. Стадия передвижения рассмотрена в отдельном разделе статьи, где показаны различные опасные случаи. Рассмотрены вопросы применения высокопрочных сталей. Вопросы усталостной прочности и механики разрушения рассмотрены отдельно. Отдельный раздел посвящен анализу риска и надежности в процессе установки морских буровых платформ

Bio-based carbonaceous composite materials from epoxidised linseed oil, bio-derived curing agent and starch with controllable functionality

Development of biomass-derived materials using sustainable practices has been one of the major scientific aims over the last few decades. A new class of bio-derived nanocomposite derived from epoxidised linseed oil, a bio-derived crosslinker and a starch based carbonaceous mesoporous material (Starbon®) has been developed. The use of Starbons® technology enables the incorporation of carbonaceous materials with tuneable surface functionality (from hydrophilic to hydrophobic). The resulting composite demonstrated good thermal stability up to 300 °C, good low temperature modulus, flexibility and uniformity, as demonstrated by TGA, DMA and SEM studies, respectively. Furthermore, the thermoset composites' swelling behaviour in solvents with a high polar index through to non-polar ones was investigated, revealing initially that non polar solvents have a greater impact on swelling than polar solvents and that in all cases the addition of filler reduces the extent of swelling. The inclusion of this carbonaceous material with hierarchical pore structure and high BET surface area may further aid the use of such composites in membrane separation applications

Valorisation of Biowastes for the Production of Green Materials Using Chemical Methods

With crude oil reserves dwindling, the hunt for a sustainable alternative feedstock for fuels and materials for our society continues to expand. The biorefinery concept has enjoyed both a surge in popularity and also vocal opposition to the idea of diverting food-grade land and crops for this purpose. The idea of using the inevitable wastes arising from biomass processing, particularly farming and food production, is, therefore, gaining more attention as the feedstock for the biorefinery. For the three main components of biomass—carbohydrates, lipids, and proteins—there are long-established processes for using some of these by-products. However, the recent advances in chemical technologies are expanding both the feedstocks available for processing and the products that be obtained. Herein, this review presents some of the more recent developments in processing these molecules for green materials, as well as case studies that bring these technologies and materials together into final products for applied usage

Application of Green Building Technologies in Urals Region

A tendency to build high-rise buildings is common for all developing Russian cities. Sustainability and energy efficiency of such buildings are issues of foremost importance besides the strength and reliability of building structures. Nowadays, both of these terms are united in the concept of "green building". The green building concept includes design, construction, and service of buildings aimed at creating comfortable microclimate, increasing energy efficiency, and reducing the environmental impact. In this work the analysis of distinctive features of designing green buildings in Ural region is given on the example of high-rise buildings constructed in Ekaterinburg. The influence of green building technologies on architectural, planning, and design solutions and selection of construction materials is explored as well as aspects of aerodynamics inside and outside the building. The influence of air flows on air permeability of building structures is assessed. The article also describes innovative solutions for creating required microclimate inside the building. © Published under licence by IOP Publishing Ltd

Computer simulation-based analysis of wind load effect on structural capacity of skywalk between Hyatt Regency hotel and multipurpose building complex Iset Tower in Ekaterinburg

This article contains a computer - aided analysis of bearing capacity under wind load for a standard attachment fixture which one is most frequently used for mounting transparent structures. The analysis results of peak positive and negative wind loads acting on the enveloping structure are presented. The stress-strain state of the skywalk facade fixture unit in the elastic strain stage is analyzed. Maximal values of force influence on the plastic deformation of the fixture unit components arise. They are determined on the basis of a nonlinear analysis. The object of the research is a skywalk between the Hyatt Regency hotel building and the Iset Tower high-rise building in Ekaterinburg that is being designed currently. Simulation models and computational experiments were made in ANSYS CFX software complex. © Published under licence by IOP Publishing Ltd.The work was supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0006