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    ABSTRACT: Small-scale experiments to investigate the self-sustaining decomposition (SSD) behaviour of NPK 16.16.16 fertilizer have been undertaken. These experiments show that this material will undergo self-sustaining decomposition and are used to give insight into the behaviour of the reaction. A three-step decomposition process is observed leading to a self-sustained reaction reaching temperatures of 200-350°C. The measured heat of reaction is 0.73-1.8 MJ/kg. Measurements are applied to the events that occurred aboard the ship Ostedijk in 2007 in which a SSD reaction occurred. The mass loss rate from the cargo was calculated to range from 0.5 kg/s on the first day to 12 kg/s on the last day. From this measurement, the maximum fire size was estimated to be in the range 5.8-29 MW.
    Journal of hazardous materials 02/2011; 186(1):731-7.
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    ABSTRACT: Standard flammability tests, like the Cone Calorimeter, were developed several decades ago and provided sufficient flammability data for the purposes of the time. However, recent pyrolysis models have revealed the limitations of the standard test in providing adequate data for current flammability analysis and modelling. This paper reviews the assumptions in the standard test and proposes a novel sample holder for the cone calorimeter which incorporates a large block of aluminium at the rear face of the sample under test. This allows the heat losses at the rear face of the sample to be measured precisely and enables more accurate calculation of the material flammability properties. Tests of PA6 and a nano-composite of PA6 & Cloisite 30B, carried out using the standard and new sample holders, are presented and discussed. The peak of high heat release rate observed in standard tests of PA6 is not observed using the novel sample holder, where the burning behaviour of PA6 and the nano-composite material are largely similar. The implications of these observations are discussed.
    Polymer Degradation and Stability - POLYM DEGRAD STABIL. 01/2011; 96(3):314-319.
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    ABSTRACT: When building fires occur in large, open compartments they rarely burn uniformly across an entire floor plate of a structure. Instead, they tend to travel, igniting fuel in their path and burning it out as they move to the next fuel package. Current structural fire design methods do not account for these types of fires. This paper applies a novel methodology for defining a family of possible heating regimes to a framed concrete structure using the concept of travelling fires. A finite-element model of a generic concrete structure is used to study the impact of the family of fires; both relative to one another and in comparison to the conventional codified temperature–time curves. It is found that travelling fires have a significant impact on the performance of the structure and that the current design approaches cannot be assumed to be conservative. Further, it is found that a travelling fire of approximately 25% of the floor plate in size is the most severe in terms of structural response. It is concluded that the new approach is simple to implement, provides more realistic fire scenarios, and is more conservative than current design methods.
    Engineering Structures - ENG STRUCT. 01/2011; 33(5):1635-1642.
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    ABSTRACT: A new methodology to effectively forecast fire dynamics based on assimilation of sensor observations is presented and demonstrated. An inverse modelling approach with a two-zone model is used to forecast the growth of a compartment fire. Sensor observations are assimilated into the model in order to estimate invariant parameters and thus speed up simulations and recover information lost by modelling approximations. A series of cases of a compartment fire radially spreading at different growth rates (slow, medium and fast) are used to test the methodology. Spread rate, entrainment coefficient and smoke transport time are the invariant parameters estimated via a gradient-based optimization method with tangent linear differentiation. The parameters were estimated accurately within minutes after ignition and the heat release rate reproduced satisfactorily in all cases. Moreover, the temperature and the height of the hot layer are forecasted with a positive lead time between 50 and 80s, depending on the fire growth rate. The results show that the simple mass and energy conservation equations and plume correlation of the zone model are suitable to forecast the main features of a growing fire. Positive lead times are reported here for the first time in fire dynamics. The results also suggest the existence of an optimal width for the assimilation window. The proposed methodology is subject to ongoing research and the results are an important step towards the forecast of fire dynamics to lead the emergency response.
    Lancet. 01/2011; 46(3):81-88.
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    ABSTRACT: The fire-safe design of concrete structures, which incorporate post-tensioned prestressing tendons, has recently been the subject of debate within the structural engineering community, particularly when unbonded post-tensioned (UPT) prestressing tendons are used. Despite several studies aimed at furthering our understanding of the response of UPT concrete structures in fire, many aspects of their response in real fires remain poorly understood. An exhaustive summary of available test data, which have been used over the past five decades to generate fire design guidance for UPT concrete structures is given. Case studies showing the response of real UPT structures in severe building fires are also discussed. In both cases, the intent is to highlight inadequacies in the current state of knowledge for UPT buildings in fire and to prioritize areas for future research.
    Fire Safety Journal 01/2011; 46(4):151-163.
  • New Phytologist 12/2010; 188(4):913-5.
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    ABSTRACT: This study considers a multi-storey composite frame subject to a fire which travels vertically between three floors. Previous work has analysed the behaviour of this structure when subject to simultaneous fires on three floors. It highlighted the importance of the cooling regime adopted and the relative axial stiffness of the steel beams to the overall behaviour of the structure. This paper extends that work by investigating the more realistic case of a vertically travelling fire. Various inter-floor time delays are considered as well as two floor beam sizes. It is found that the inter-floor time delay affects the global behaviour substantially. The behaviour is also in part dependent on the stiffness of the floor beams. Axial forces caused by thermal expansion in individual floors may induce cyclic loading on the column which is not normally considered in structural fire design but may be important in determining structural behaviour. Identifying a worst-case rate of vertical fire spread is not possible due to the range of structural responses, so it is recommended that designers consider several rates of spread and ensure structural integrity for each.
    Journal of Constructional Steel Research. 01/2010;
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    ABSTRACT: Bending moment axial force interaction diagrams are a commonly used tool in any design office. When designing for fire conditions, the large axial forces which develop place an additional importance on the consideration of the interplay between axial forces and moments. This paper presents a new method for calculating the biaxial bending moment/axial force capacity for a general section through the use of the sectional tangent stiffness. A beam–column section subject to fire is assessed, and comparisons made with simplified design tools. It is concluded that derivation of the interaction surface from the tangent stiffness matrix is possible, and that current simplified methods for fire design cannot be assumed conservative.
    Engineering Structures - ENG STRUCT. 01/2010; 32(6):1641-1649.
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    ABSTRACT: A sensor-linked modelling tool for live prediction of uncontrolled compartment fires, K-CRISP, has been developed in order to facilitate emergency response via novel systems such as FireGrid. The modelling strategy is an extension of the Monte-Carlo fire model, CRISP, linking simulations to sensor inputs which controls evolution of the parametric space in which new scenarios are generated, thereby representing real-time “learning” about the fire. CRISP itself is based on a zone model representation of the fire, with linked capabilities for egress modelling and failure prediction for structural members, thus providing a major advantage over more detailed approaches in terms of flexibility and practicality, though with the conventional limitations of zone models. Large numbers of scenarios are required, but computational demands are mitigated to some extent by various procedures to limit the parameters which need to be varied. HPC (high performance computing) resources are exploited in “urgent computing” mode. The approach adopted for steering is shown to be effective in directing the evolution of the fire parameters, thereby driving the fire predictions towards the measurements. Moreover, the availability of probabilistic information in the output assists in providing potential end users with an indication of the likelihood of various hazard scenarios. The best forecasts are those for the immediate future, or for relatively simple fires, with progressively less confidence at longer lead times and in more complex scenarios. Given the uncertainties in real fire development the benefits of more detailed model representations may be marginal and the system developed thus far is considered to be an appropriate engineering approach to the problem, providing information of potential benefit in emergency response.
    Fire Safety Journal. 01/2010;
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    ABSTRACT: Fire is a phenomenon that covers a multiplicity of scales depending on the different processes involved. Length scales range from the nanometres when addressing material flammability to the kilometres when dealing with forest fires, while time scales cover a broad spectrum too. Heating of structural elements can be measured in hours while characteristic chemical times for reactions do not exceed the millisecond. Despite these wide ranges, a series of simple scaling laws seem to describe well a multiplicity of processes associated with fire. In this paper, flaming ignition of a solid fuel will be presented within the context of general scaling laws and forest fires. Therefore, the case of highly porous vegetable fuels will be investigated to extend the theory to the forest fires application.
    The Open Thermodynamics Journal 01/2010; 4:145-155.
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