Browsing by Author "Cicione, Antonio"

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    Fire Dynamics in Informal Settlements
    (Stellenbosch : Stellenbosch University, 2019-12) Cicione, Antonio; Walls, Richard Shaun; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: In poor and densely populated countries, the rapid growth in population leads to an increase in landlessness. As a result, the number of people residing in informal settlements is increasing on a daily basis. It is estimated that there are currently one billion people living in informal settlements and this number is expected to increase in the coming years. Currently, informal settlements are being ravaged by large fires every day across the globe. Over the past decades, fire related disasters have decreased in the global north, while they have increased in the global south. Since the number of people that reside in informal settlements are expected to increase, it is a cause for serious concern to see how little is done in terms of fire safety in these communities. It is with this in mind that this dissertation focusses on developing an in-depth understanding of fire dynamics in informal settlements, with the hope that it can form the basis for future research and fire safety innovations. In this dissertation four full-scale fire experiments have been carried out: (a) a single steel sheeting clad experiment, (b) a single timber plank clad experiment, (c) a triple dwelling steel sheeting clad experiment and (d) a triple dwelling timber plank clad experiment. The single dwelling experiments are analysed using two numerical models (i.e. two-zone modelling and Fire Dynamic Simulation (FDS) modelling) to obtain an understanding of the enclosure fire dynamics and heat fluxes emitted from these dwellings. A comparison between the model and experimental results are shown. The effect of different cladding materials (i.e. timber versus steel cladding) on the enclosure fire dynamics and heat fluxes experienced is also presented, where it was found that timber dwellings are more prone to fire spread, with heat fluxes exceeding 200 kW/m2 at the openings. It was found that the FDS models captured the behaviour of the single dwelling experimental fires well, but that the material properties of the cardboard lining have a substantial effect on how the fire develops, as a result of how the fire spreads across the surface of the cardboard. This was also the most difficult aspect to capture with the numerical models. The FDS models’ predictive capabilities were further utilised to determine a preliminary critical separation distance, where it was found to be approximately 3 m between dwellings (i.e. the distance needed for fire spread between dwellings not to occur under wind free conditions). The dissertation continues by presenting the results of the multi-dwelling experiments, where the basic understandings and findings drawn from the single dwelling experiments were used to examine the effect of different cladding materials on fire spread between dwellings. The multi-dwelling experimental results concurred that the timber dwellings are more prone to fire spread. These results highlighted the dangers of these closely spaced dwellings. For the timber clad dwellings, the overall spread time (i.e. from the start of flashover in the first dwelling to the end of flashover in the last dwelling) was approximately 4 minutes. Simplified FDS models are developed to predict fire spread between multiple dwellings, with the hope that these models can be improved over time so that they can be used to study housing configurations and fire spread interventions.
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    Fire safety engineering guideline for informal settlements : towards practical solutions for a complex problem in South Africa
    (Stellenbosch University, 2020) Walls, Richard; Cicione, Antonio; Pharoah, Robyn; Zweig, Patricia; Smith, Mark; Antonellis, Danielle; Walls, Richard
    ENGLISH ABSTRACT: Informal settlements are growing rapidly, and in Africa they are likely to double in size within the coming few decades. Informal settlements (IS) (also known by names such as slums, ghettos, favelas and shantytowns) are typically dense, and people’s homes are built from highly combustible materials. Hence, when a fire breaks out it can spread rapidly, leaving thousands homeless. Every year in South Africa fires are affecting large numbers of people, costing municipalities millions of rands (ZAR), and are severely hindering the upliftment of the poorest in our communities. This guideline seeks to provide a holistic approach to improving fire safety for communities. It is important to realise that this complex problem can only be improved by a multi-sectoral response addressing various issues such as: reducing the risk of ignition, providing early warning systems, having community involvement, having well-resourced and well-prepared fire departments, reducing the combustible nature of homes, and many other similar factors. The audience of this report is broad in that it seeks to assist fire departments, local municipalities, national government, engineers, town planners and non-governmental organisations involved in IS fire safety. This work initially provides an understanding of communities living in settlements, as often interventions overlook the daily reality of these people which leads to interventions being ineffective. Fire behaviour, fire spread and fire safety engineering is then discussed, and it is shown how this can be applied to ISs. This is done to dispel many common myths, and to show what can, and can’t, improve fire safety. To understand IS fire incidents a timeline of a typical fire incident is provided, along with a case study on the 2017 Imizamo Yethu disaster. Many interventions, strategies and devices are discussed, looking at what could be adopted to improve fire safety. It is important to realise that a basket of solutions is typically needed, and a single intervention may have a very limited impact. A list of tasks that communities can undertake before, during and after a fire incident provides a useful resource for organisations working with communities. Ultimately there is no easy solution to this problem. However, through a concerted, evidence-based approach significant fire safety improvements can be made to help the poorest in our land.
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    Towards the development of a probabilistic approach to informal settlement fire spread using ignition modelling and spatial metrics
    (MDPI, 2020-11-15) Cicione, Antonio; Gibson, Lesley; Wade, Colleen; Spearpoint, Michael; Walls, Richard; Rush, David
    ENGLISH ABSTRACT: Large conflagrations of informal settlements occur regularly, leaving thousands of people homeless daily and taking tens of thousands of lives annually. Over the past few years, a large amount of data has been collected from a number of full-scale informal settlement fire experiments. This paper uses that data with a semi-probabilistic fire model previously proposed by the authors, to illustrate the potential applications of the fire spread method proposed. The current model is benchmarked against a 20-dwelling full-scale informal settlement fire experiment, and the effects of the (a) ignition criteria, (b) wind direction, and (c) wind speeds on the predicted fire spread rates are investigated through the use of a parametric study. Colour maps of the fire spread rates and patterns are then used to visually interpret the effects of different types of fire scenarios and fire breaks. Finally, the fire spread capability within B-RISK is used to derive a linear equation for the potential fire spread rate as a function of the settlement spatial metrics (e.g., density and distance to nearest neighbour). To further illustrate the potential application of this work, the fire spread rate equation is then applied across the whole of Cape Town, South Africa, to show the 10 informal settlement areas most at “risk” of large conflagrations.