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1 – 10 of 554Alexandra Byström, Johan Sjöström, Ulf Wickström, David Lange and Milan Veljkovic
A localized fire is a fire which in a compartment is unlikely to reach flash-over and uniform temperature distribution. Designing for localized fires is generally more difficult…
Abstract
A localized fire is a fire which in a compartment is unlikely to reach flash-over and uniform temperature distribution. Designing for localized fires is generally more difficult than for flash-over compartment fires because of the complexity of the problem. There is also a lack of experimental data. We report here on a full scale test series on a steel column exposed to localized fires. The setup is a 6 meters tall hollow circular column, ϕ = 200 mm with a steel thickness of 10 mm. The unloaded column was hanging centrally above different pool fires. Temperatures of gas and steel were measured by thermocouples, and adiabatic surface temperatures at the steel surface were measured by plate thermometers of various designs. The results are compared with estimates based on Eurocode 1991-1-2 which in all cases studied overestimate the thermal impact for this setup. The input from plate thermometers was used to compute the steel temperatures using finite element methods. Excellent agreement was found if the radiation exchange within the column due to asymmetry of the exposure was taken into account.
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CONVENTIONAL aircraft thermometers are of the platinum‐resistance type, comprising one arm of a Wheatstone bridge network. The meter connected to the network is graduated on a…
Abstract
CONVENTIONAL aircraft thermometers are of the platinum‐resistance type, comprising one arm of a Wheatstone bridge network. The meter connected to the network is graduated on a temperature scale and different values are due to changes in the resistance of the platinum element. These arise from variations in the temperature of the air immediately in contact with the element or its protective casing. Any indicated temperature is a measure of the temperature of the air in contact with the thermometer. It is also the temperature of those parts of the aircraft over which the air is moving at the same speed as it is flowing past the thermometer. Since the air does not flow at the same speed over all parts of the aircraft it is clear that by mounting thermometers in different positions on an aircraft, different temperatures will be obtained. Due mainly to kinetic heating none of these will be the true temperature of the air in the free stream—i.e. away from the influence of the aircraft—and to obtain the free stream air temperature it is necessary to apply corrections. For many purposes, particularly meteorological research, it is important to be able to obtain true air temperatures from indicated air temperatures quickly and accurately and it is with this purpose in mind that the diagram to be described was devised and constructed.
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The Turner 50‐ton upstroke press is a self‐contained hydraulic press designed specifically for compression moulding of plastics.
Batuhan Der, Sylvie Raszková, František Wald, Gisèle Bihina, Christian Gaigl, Vasile Rus and Mikko Malaska
This study aims to propose a new design value, based on experimental and numerical studies, for surface emissivity of zinc hot-dip galvanized members exposed to fire.
Abstract
Purpose
This study aims to propose a new design value, based on experimental and numerical studies, for surface emissivity of zinc hot-dip galvanized members exposed to fire.
Design/methodology/approach
The paper sums up experiments, used specimens and also shows results. Four experiments were performed in a horizontal furnace and one test in a fire compartment of the experimental building. Several tests were carried out for determination of the surface emissivity of galvanized steel structures in fire. The experimental and numerical studies were used for preparation of new generation of the structural steel fire standard Eurocode EN 1993-1-2:2025.
Findings
Hot-dip galvanizing is one of the most widely used processes for corrosion protection of steel products. The new design value for surface emissivity of zinc hot-dip galvanized members exposed to fire is determined using experimental results as 0.35. The value is proposed for next generation of EN 1993-1-2:2025. If hot-dip galvanization additionally can contribute beneficially to the fire resistance of unprotected steel members, it would be a huge economic advantage.
Originality/value
Experimental studies in the past years have indicated the influence of hot-dip galvanizing on the heating of steel members. This study suggests 50% reduction of the surface emissivity of a carbon steel member. This amendment will be incorporated in future versions of Eurocodes 3 and 4 and has already been implemented in some fire design tools for steel members in order to consider the beneficial contribution of hot-dip galvanized for fire-resistance requirements of less than 60 min.
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Fateme Sayanjali, Nazanin Ezazshahabi and Fatemeh Mousazadegan
The aim of the present study is to investigate the effect of fabric weave structure on air permeability and its relation with the garment ventilation.
Abstract
Purpose
The aim of the present study is to investigate the effect of fabric weave structure on air permeability and its relation with the garment ventilation.
Design/methodology/approach
For this purpose, five groups of cotton/polyester shirting fabrics with plain, T2/1, T2/2, T3/1 and T3/3 weave structures were studied. In order to evaluate ventilation, the garment samples were prepared in different sizes, so that the thickness of the air gap formed between the garment and the body simulator varies by zero, 1.5, 1.2 and 2.9 cm. The effect of wind and its speed (1, 2 and 3 m/s) on clothing ventilation has also been evaluated.
Findings
The results indicated that the rise of wind speed and air gap thickness, due to the increased convective heat transfer, would diminish the air gap temperature of clothing and improves its ventilation. In addition, the fabric weave pattern influences the air ability to pass through the fabric, thus affecting the ventilation capability of the garment.
Originality/value
Garments made of fabrics with higher structural firmness, such as the plain, not only have lower air permeability, but also has weaker ventilation capability.
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In fire condition, the limiting temperature of a restrained steel beam depends on a few parameters, e.g. temperature distributions along and across the beam, beam’s load ratio and…
Abstract
Purpose
In fire condition, the limiting temperature of a restrained steel beam depends on a few parameters, e.g. temperature distributions along and across the beam, beam’s load ratio and span length. The purpose of this study is to investigate the structural fire behaviour of axially restrained steel beams under different beam’s load ratios, taking into consideration the effect of the beam’s end connections configuration.
Design/methodology/approach
A three-dimensional finite element (FE) computer model has been developed to simulate the structural fire behaviour of axially restrained steel beams and their end connections. After successfully validating the developed model against the outcomes of the available large-size fire resistance experiments, the FE model has been used in a parametric study to investigate the beam’s load ratio effect on the behaviour of the axially restrained steel beams and their end connections.
Findings
The parametric study showed that increasing the beam loading level significantly increased the beam deflections at elevated temperatures; where, increasing the beam’s load ratio from 0.5 to 0.9 reduced the beam fire resistance by about 100 s. In contrast, decreasing the beam’s load ratio from 0.5 to 0.3 allowed the beam to easily achieve a 30-min fire resistance rating with no fire protection applied.
Originality/value
Experimental parametric studies are difficult to control in a laboratory setting and are also expensive and time consuming. Therefore, the reasonable accuracy of the validated FE model in reproducing the experimental fire behaviour of steel beams and their end connections makes it a very useful tool for both numerical and analytical studies.
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Vaishali Sahu, Rounak Attri, Prashast Gupta and Rakesh Yadav
This paper aims to study the effect of the addition of water treatment plant sludge (WTPS) and processed tea waste (PTW) on the properties of burnt clay bricks. The reuse of WTP…
Abstract
Purpose
This paper aims to study the effect of the addition of water treatment plant sludge (WTPS) and processed tea waste (PTW) on the properties of burnt clay bricks. The reuse of WTP sludge as a raw material for brick production is a long-term approach, to sludge disposal, for economic and environmental sustainability. Sludge have been added at 10, 20, 30 and 40% and processed tea waste at 5% (by weight) in replacement of clay for brick manufacturing. Each batch of hand-moulded bricks was fired in a heat controlled furnace at a temperature of 990°C. The compressive strength has been found to increase with the sludge content, however, a slight decrease in compressive strength was observed with tea waste addition. Further, PTW addition has improved the thermal insulation of bricks as compared to controlled bricks. The study shows that 40% WTPS, 5% PTW and 55% natural clayey soil can be considered as an optimum mix for bricks with good compressive strength as well as improved thermal insulation property.
Design/methodology/approach
Four different mixing ratios of sludge at 10, 20, 30 and 40% of the total weight of sludge-clay mixtures were used to make bricks. Similarly, PTW was investigated as a substitute of natural clayey soil in brick manufacturing. Each batch of hand-moulded bricks was fired in a heat controlled furnace at a temperature of 990°C. The physical, mechanical and engineering properties of the produced WTPS bricks and PTW bricks were determined and evaluated according to various Indian Standard Codes of Specification for burnt clay bricks and certain reference books.
Findings
The results exhibited that WTP sludge and PTW can be used to produce good quality brick for various engineering applications in construction and building. Increasing the sludge content increases the compressive strength. Moreover, thermal insulation of PTW bricks depicted an upward trend when compared to controlled bricks. Hence, an optimum mixture of 40% WTPS, 5% PTW and 55% natural clayey soil was found, at which bricks showed good compressive strength as well as improved thermal insulation property of the building material.
Research limitations/implications
The present work provides a sustainable solution for disposal of WTP sludge and tea waste. Utilization of these waste materials in brick manufacturing is viable and economic solution.
Practical implications
Bricks with 40% WTP sludge and 5% processed tea waste proved to be economic, technically sound for construction purposes with added thermal insulation properties.
Social implications
Bulk amount of waste such as WTP sludge is a threat to society owing to its environmental implications of disposal. Authors propose to use WTP sludge and tea waste for brick manufacturing and provide a solution to its disposal.
Originality/value
Water treatment plant sludge along with tea waste have not been tried for brick manufacturing so far. Hence, the composition is new in itself and also have resulted into good performance.
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Margo A. Mastropieri, Thomas E. Scruggs, Janet Graetz and Nicole Conners
This chapter reports on the results from several extended qualitative investigations of co-teaching in science and social studies content area classes, on both elementary and…
Abstract
This chapter reports on the results from several extended qualitative investigations of co-teaching in science and social studies content area classes, on both elementary and secondary levels. In these investigations, co-teaching partners were studied and interviewed over several years, with the view of uncovering attitudes and procedures closely associated with successful collaborative partnerships. In some cases, these investigations took place in the context of implementation of research-based instructional strategies. Analysis of data from these investigations revealed that there was considerable variability in the way co-teaching practices were implemented, the attitudes toward co-teaching expressed by teachers, and the success of the co-teaching partnerships. It was thought that several variables, including content expertise, concerns for high-stakes testing, and the personal compatibility of co-teachers played an important role in the success of the co-teaching relationship.