Search results

1 – 10 of over 3000
To view the access options for this content please click here
Article

Jean-Christophe Mindeguia, Guillaume Cueff, Virginie Dréan and Gildas Auguin

The fire resistance of wooden structures is commonly based on the calculation or measurement of the char layer. Designers usually estimate the char layer at the surface of…

Abstract

Purpose

The fire resistance of wooden structures is commonly based on the calculation or measurement of the char layer. Designers usually estimate the char layer at the surface of a structural element by using analytical models. Some of these charring models can be found in regulations, as Eurocode 5. These analytical models, quite simple to use, are only reliable for the standard fire curve. In that case, the design of the structure is qualified as “prescriptive-based design” and can lead to oversizing the structure. Optimization of a structure can be achieved by using a “Performance-based design”, where realistic fire scenarios are taken into account by means of more or less complex models [parametric fires, two-zones models, computational fluid dynamics (CFD)]. For these so-called “natural fires”, no model for charring is available. The purpose of this paper is to present a novel methodology for applying a performance-based design to a simple timber structure.

Design/methodology/approach

This paper presents the development of a numerical model aiming to simulate the thermal transfer and charring in wood, under any type of thermal exposure, including non-standard fire curves. After presenting the physical background, the model is calibrated and compared to existing experimental studies on wood samples exposed to different fire curves. The model is then used as a tool for assessing the fire resistance of a common wooden structure exposed to standard and non-standard fire curves.

Findings

The results show that the fire resistance is obviously dependent on the choice of the thermal exposure. The reliability of the model is also discussed and the importance of taking into account particular reactions in wood during heating is underlined.

Originality/value

One aim of this paper is to show the opportunity to apply a performance-based approach when designing a wooden structure. It shows that more knowledge of the material behaviour under non-standard fires is still needed, especially during the decay phase.

Details

Journal of Structural Fire Engineering, vol. 9 no. 1
Type: Research Article
ISSN: 2040-2317

Keywords

To view the access options for this content please click here
Article

Xiansheng Zhang, Xianjing Du, Lili Wang and Meiwu Shi

The purpose of this paper is to investigate the effect of char on the flame retardancy of fabrics by a cone calorimeter, which is an important factor to compare the flame…

Abstract

Purpose

The purpose of this paper is to investigate the effect of char on the flame retardancy of fabrics by a cone calorimeter, which is an important factor to compare the flame retardancy of different fabrics.

Design/methodology/approach

Cone calorimeter measurements were carried out in a Fire Testing Technology (UK) apparatus at the heat fluxes of 50 and 75 kW/m2. Fabrics with one and three layers were employed, with the name of cotton1, cotton3, FR cotton1, FR cotton3, PMIA1 and PMIA3. The dimension of the fabric was 100×100 mm2. A cross-steel grid was used to prevent the fabrics from curling during burning. The distance between the bottom of the cone heater and the top of the sample was 25 mm.

Findings

This work was generously supported by National Key R&D Program of China (Project No. 2017YFB0309000), Natural Science Foundation of Shandong Province of China (Project No. ZR2019BEM026), Natural Science Foundation of China (Project No. 51803101) and China postdoctoral science foundation funded project (Project No. 2018M632619).

Originality/value

The present research provides insight into the effect of the char formation on the flame retardancy of the fabrics, and a method to comprehensively investigate the char influence in the flame retardancy of the fabrics by a cone calorimeter is proposed.

Details

International Journal of Clothing Science and Technology, vol. 31 no. 4
Type: Research Article
ISSN: 0955-6222

Keywords

To view the access options for this content please click here
Article

Joachim Schmid, Alessandro Santomaso, Daniel Brandon, Ulf Wickström and Andrea Frangi

The purpose of this study is to investigate the influencing factors on the charring behaviour of timber, the char layer and the charring depth in non-standard fires.

Abstract

Purpose

The purpose of this study is to investigate the influencing factors on the charring behaviour of timber, the char layer and the charring depth in non-standard fires.

Design/methodology/approach

This paper summarizes outcomes of tests, investigating the influences on the charring behavior of timber by varying the oxygen content and the gas velocity in the compartment. Results show that charring is depending on the fire compartment temperature, but results show further that at higher oxygen flow, char contraction was observed affecting the protective function of the char layer.

Findings

In particular, in the cooling phase, char contraction should be considered which may have a significant impact on performance-based design using non-standard temperature fire curves where the complete fire history including the cooling phase has to be taken into account.

Originality/value

Up to now, some research on non-standard fire exposed timber member has been performed, mainly based on standard fire resistance tests where boundary conditions as gas flow and oxygen content especially in the decay phase are not measured or documented. The approach presented in this paper is the first documented fire tests with timber documenting the data required.

Details

Journal of Structural Fire Engineering, vol. 9 no. 3
Type: Research Article
ISSN: 2040-2317

Keywords

To view the access options for this content please click here
Article

Mattia Tiso and Alar Just

Insulation materials’ contribution to the fire resistance of timber frame assemblies may vary considerably. At present, Eurocode 5 provides a model for fire design of the…

Abstract

Purpose

Insulation materials’ contribution to the fire resistance of timber frame assemblies may vary considerably. At present, Eurocode 5 provides a model for fire design of the load-bearing function of timber frame assemblies with cavities completely filled with stone wool. Very little is known about the fire protection provided by other insulation materials. An improved design model which has the potential to consider the contribution of any insulation material has been introduced by the authors. This paper aims to analyze the parameters that describe in a universal way the protection against the charring given by different insulations not included in Eurocode 5.

Design/methodology/approach

A series of model-scale furnace tests of floor specimens for three different insulation materials were carried out. An analysis on the charring depth of the residual cross-sections was conducted by means of a resistograph device.

Findings

The study explains the criteria and procedure followed to derive the coefficients for the improved design model for three insulations involved in the study.

Originality/value

This research study involves a large experimental work which forms the basis of the proposed design model. This study presents an important step for fire resistance calculations of timber frame assemblies.

Details

Journal of Structural Fire Engineering, vol. 9 no. 3
Type: Research Article
ISSN: 2040-2317

Keywords

To view the access options for this content please click here
Article

J.L. Lin and C.S. Yang

This work experimentally and numerically investigates the aerodynamic heating of the charring‐ablating materials.

Abstract

Purpose

This work experimentally and numerically investigates the aerodynamic heating of the charring‐ablating materials.

Design/methodology/approach

The experimental model is a stainless steel cone with an attached charring ablator, in which supersonic hot flow impinges. The initial numerical simulation is based on physical and mathematical models, including one‐dimensional, unsteady energy transport and mass conservation equations, coupled with calculations of aerodynamic heating, thermal degradation, heat transfer of the ablating surface and the ablation model. The problem is solved by an efficient numerical method.

Findings

The numerical calculations involve the time history of the temperature distribution inside the charring material and the backup structure. The results are consistent with the experimental data.

Originality/value

This study proposes an effective method to correlate one's own ablation rate equation, by a method of trial and error to find the correlation constants, and the corresponding time histories of the ablation rate or temperature that are closest to one's own experimental data. Then the correlation of the surface ablation rate can be applied with confidence in the numerical calculation of other cases.

Details

Aircraft Engineering and Aerospace Technology, vol. 77 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

To view the access options for this content please click here
Article

George K. Chacko

Gives an in depth view of the strategies pursued by the world’s leading chief executive officers in an attempt to provide guidance to new chief executives of today…

Abstract

Gives an in depth view of the strategies pursued by the world’s leading chief executive officers in an attempt to provide guidance to new chief executives of today. Considers the marketing strategies employed, together with the organizational structures used and looks at the universal concepts that can be applied to any product. Uses anecdotal evidence to formulate a number of theories which can be used to compare your company with the best in the world. Presents initial survival strategies and then looks at ways companies can broaden their boundaries through manipulation and choice. Covers a huge variety of case studies and examples together with a substantial question and answer section.

Details

Asia Pacific Journal of Marketing and Logistics, vol. 11 no. 2/3
Type: Research Article
ISSN: 1355-5855

Keywords

To view the access options for this content please click here
Article

Andrzej Marian Swiatkowski

collective action in case of a collective labour conflict. Poland ratified the Charter in 1997, that is seventeen years after the world‐famous Polish Independent and…

Abstract

collective action in case of a collective labour conflict. Poland ratified the Charter in 1997, that is seventeen years after the world‐famous Polish Independent and Self‐Governing Trade Union Solidarity had been established. In order to commemorate the 25th anniversary of the establishment of the Union, I shall present a fragment of a monograph on the European Social Charter and, more specifically, on the right of workers to organise and participate in strikes. By means of the aforementioned regulation, both parties of collective employment relationships (workers and employers) were granted the right to take collective action

Details

Managerial Law, vol. 47 no. 6
Type: Research Article
ISSN: 0309-0558

Keywords

To view the access options for this content please click here
Article

Li‐teh Sun

Man has been seeking an ideal existence for a very long time. In this existence, justice, love, and peace are no longer words, but actual experiences. How ever, with the…

Abstract

Man has been seeking an ideal existence for a very long time. In this existence, justice, love, and peace are no longer words, but actual experiences. How ever, with the American preemptive invasion and occupation of Afghanistan and Iraq and the subsequent prisoner abuse, such an existence seems to be farther and farther away from reality. The purpose of this work is to stop this dangerous trend by promoting justice, love, and peace through a change of the paradigm that is inconsistent with justice, love, and peace. The strong paradigm that created the strong nation like the U.S. and the strong man like George W. Bush have been the culprit, rather than the contributor, of the above three universal ideals. Thus, rather than justice, love, and peace, the strong paradigm resulted in in justice, hatred, and violence. In order to remove these three and related evils, what the world needs in the beginning of the third millenium is the weak paradigm. Through the acceptance of the latter paradigm, the golden mean or middle paradigm can be formulated, which is a synergy of the weak and the strong paradigm. In order to understand properly the meaning of these paradigms, however, some digression appears necessary.

Details

International Journal of Sociology and Social Policy, vol. 25 no. 6/7
Type: Research Article
ISSN: 0144-333X

Keywords

To view the access options for this content please click here
Article

E. Theuns, J. Vierendeels and P. Vandevelde

This paper describes a one dimensional moving grid model for the pyrolysis of charring materials. In the model, the solid is divided by a pyrolysis front into a char and a…

Abstract

This paper describes a one dimensional moving grid model for the pyrolysis of charring materials. In the model, the solid is divided by a pyrolysis front into a char and a virgin layer. Only when the virgin material reaches a critical temperature it starts to pyrolyse. The progress of the front determines the release of combustible volatiles by the surface. The volatiles, which are produced at the pyrolysis front, flow immediately out of the solid. Heat exchange between those volatiles and the char layer is taken into account. Since the model is used here as a stand‐alone model, the external heat flux that heats up the solid, is assumed to be known. In the future, this model will be coupled with a CFD code in order to simulate fire spread. The char and virgin grid move along with the pyrolysis front. Calculations are done on uniform and on non‐uniform grids for the virgin layer. In the char layer only a uniform grid is used. Calculations done with a non‐uniform grid are about 3 times faster than with a uniform gird. The moving grid model is compared with a faster but approximate integral model for several cases. For sudden changes in the boundary conditions, the approximate integral model gives significant errors.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 12 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article

Joseph Adewumi Oyebanji and Sunday Olayinka Oyedepo

This study aims to investigate the effect of reactor temperature on softwood and hardwood pyrolysis. Experiments are performed at six temperature levels ranging from 300…

Abstract

Purpose

This study aims to investigate the effect of reactor temperature on softwood and hardwood pyrolysis. Experiments are performed at six temperature levels ranging from 300 to 800°C under N2 atmosphere. The weights of char, tar and gas yields produced were measured and recorded in percentage of initial weight of the pyrolyzed samples. Results of the study showed that hardwood produces maximum char, tar and gas yields of 41.02 per cent at 300°C,44.10 per cent at 300°C and 56.86 per cent at 800°C, respectively, whereas softwood produces maximum yields of 30.10 per cent at 300°C, 28.25 per cent at 300°C and 68.73 per cent at 800°C, respectively. Proximate analysis shows that volatile matter, fixed carbon, ash content and moisture content of hardwood are 74.83, 14.28, 2.81 and 8.08 per cent, respectively, and that of softwood are 79.76, 12.65, 0.98 and 6.61 per cent, respectively. Result of the elemental analysis results shows that the carbon, hydrogen, nitrogen, oxygen and sulphur contents for hardwood are 52.20, 6.45, 0.68, 39.64 and 1.03 per cent, respectively, and that of softwood are 45.95, 4.57, 0.56, 48.13 and 0.79 per cent, respectively. The higher heating value of hardwood and softwood are 21.76 and 16.50 kJ/g respectively. This study shows that char and tar yields decrease with increase pyrolysis temperature, whereas gas yield increases as pyrolysis temperature increases for the wood samples considered. At all temperatures considered in this study, gas yields are higher than tar and char yields for softwood, whereas for hardwood, tar yield decreases with increase in temperature with accompanying increase in gas yield.

Design/methodology/approach

Experiments are performed at six temperature levels ranging from 300 to 800°C under N2 atmosphere.

Findings

At all temperatures considered in this study, gas yields are higher than tar and char yields for softwood, whereas for hardwood, tar yield decreases with increase in temperature with accompanying increase in gas yield.

Originality/value

Results of the study showed that hardwood produces maximum char, tar and gas yields of 41.02 per cent at 300°C,44.10 per cent at 300°C and 56.86 per cent at 800°C, respectively, whereas softwood produces maximum yields of 30.10 per cent at 300°C, 28.25 per cent at 300°C and 68.73 per cent at 800°C, respectively.

Details

World Journal of Engineering, vol. 15 no. 1
Type: Research Article
ISSN: 1708-5284

Keywords

1 – 10 of over 3000