Thesis (M. Sc.)--University of Hong Kong, 2003.

Thesis (MSocSc(LegSt&CrimJus)) - University of Queensland, 2006. / Includes bibliography.

Thesis (MS)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Catherine A. Zabinski. Includes bibliographical references (leaves 77-86).

The effectiveness of harvesting slash treatments are questionable when wild fires, fuelled by post harvesting slash, burn out of control. In order to quantify effectiveness of various slash treatments, fire behaviour in Pinus patula and Eucalyptus macarthurii compartments in the Highveld area (Piet Retief) of Mpumalanga, South Africa, were assessed after application of five different post-harvesting slash treatments. Treatments included mulching, chopper rolling, windrowing, removal of slash (inter-windrowing) and broadcasting. Independent fuel and environmental variables were measured prior and during application of fire to the study areas and effects on fire behaviour were compared afterwards. Dependant fire behaviour variables such as the rate of spread, fire temperature and flame height were measured in respective slash treatment plots and compared. Results of the study indicated that fire behaviour assessed in mulched areas in both the P. patula and E. macarthurii compartments were significantly less intense when compared to fire behaviour in chopper roll, broadcast and windrow treatments. Fire behaviour in mulched plots compared favourably with areas where harvesting slash was removed (inter-windrow treatment). Comparisons between fuel loads of different treatments also indicated accelerated mineralization of organic material in mulched areas. Mulching of harvesting slash seems to be an effective method to restrict fire behaviour in post-harvesting compartments and should be considered as part of a fire management strategy.

An analysis of the fire occurrences parameters is essential to save human lives, property, timber resources and conservation of biodiversity. Data conversion formats such as raster to ASCII facilitate the integration of various GIS software’s in the context of RS and GIS modeling. This research explores fire occurrences in relation to human interaction, fuel density interaction, euclidean distance from the perennial streams and slope using artificial neural networks. The human interaction (ignition source) and density of fuels is assessed by Newton’s Gravitational theory. Euclidean distance to perennial streams and slope that do posses a significant role were derived using GIS tools. All the four non linear predictor variables were modeled using the inductive nature of neural networks. The Self organizing feature map (SOM) utilized for fire size risk classification produced an overall classification accuracy of 62% and an overall kappa coefficient of 0.52 that is moderate (fair) for annual fires.

This work is an experimental and theoretical analysis of factors and conditions affecting smoke and carbon monoxide (CO) production in corridor-like enclosure fires. Thirty eight experiments were performed in a three metre long corridor-like enclosure having a cross section 0.5 m x 0.5 m, door-like openings in the front panel and a propane gas burner located near the closed end. Measurements of smoke and carbon monoxide concentrations were performed at locations inside the enclosure and also in the exhaust duct of a hood collecting the combustion products. The main conclusion of this work is that smoke production depends not only on the fuel and Global Equivalence Ratio (GER) - as is reported in the literature - but also on the temperatures and residence time inside the enclosure, at least for the experimental conditions examined in this study. Additionally, it was found that the smoke concentration inside the enclosure was increasing during the ventilation controlled regime even after external burning started. Such increase was verified by temperature, smoke and velocity measurements inside the enclosure. The increase was due to reverse flow behind the flames travelling along the corridor. Namely, the gases reversed direction behind the flames with hot gases travelling in the upper layer backwards towards the closed end of the corridor in contrast to hot gas movements towards the opening in front of the flames. This recirculation was confirmed by velocity and oxygen concentration measurements in the upper and lower layers inside the enclosure. In addition, the present results show that the relationship reported in the literature between smoke and carbon monoxide production during overventilated conditions yco/ys ≈ constant, is no longer valid during an underventilated enclosure fire. The ratio yco/ys increases for the Global Equivalence Ratios of the enclosure greater than one. The obtained results are useful for CFD validation and specifically applicable for assessing smoke hazards in corridor fires in buildings where smoke concentrations can be much larger than anticipated owing to leakage to adjacent rooms behind travelling flames.

The interaction between the heat flux and fluid flow of an engine compartment fire and the windshield of a post-collision passenger vehicle has been studied using analytical methods. A computational fluid dynamics model of this scenario has been developed with TASCflow using a turbulent, reacting, multi-component fluid flow in a multi-grid domain with conjugate heat transfer objects. A group of computer programs have also been created to automate the grid generation and model construction processes. Calculation tools have also been developed using aspects of fire dynamics for the purpose of making comparisons to the results of CFD modeling as well as experimental measurements. A framework has been established for the modeling and validation of the windshield problem using the tools developed in this study.

A smoke explosion is generally considered as a deflagration of the accumulated unburned fuel inside a closed compartment. However, the term smoke explosion has been widely misused for decades with a great deal of confusion, and very little research has been done towards this topic. The purpose of this research is to study the smoke explosion phenomenon in much more detail through the development of a fire scenario under various experimental conditions including ventilation size, fuel elevation and fuel mass, so that a more comprehensive understanding of this phenomenon can be achieved. A total of twenty experiments are carried out including both exploratory and final experiments. Thirteen experiments result in smoke explosions, among which there are five experiments result in more than one smoke explosion. A phenomenon referred as smoldering decay is observed in all experiments with smoke explosions, making it one of the precursors of the smoke explosion phenomenon. The smoldering decay is often indicated by an exponential decay of the temperature and is caused by the low oxygen concentration within the compartment. Based on the analysis, it is found that the vent size must be at least 50 mm in diameter in order for smoke explosions to occur. The fuel elevation has no influence on the occurrence of the smoke explosion. However when the fuel is placed near the ceiling, the temperature, the mass flow rate and the heat release rate are all lowered significantly. The size of the fuel also has no significant influence except for the duration of the experiment. The concentration of CO is scattered in the range of 1.9% and 4.3% when explosions occur. Hence, the accumulation of CO is considered not to be the direct cause for the smoke explosion. The triggering factor for smoke explosions is believed to be the flammable limit formed by the mixture of hydrocarbon and CO. The pressure difference caused by the explosion inside the compartment has to be at least 27 Pa for it to be considered as a smoke explosion.

The last decades have seen a surge in the construction of tall buildings all over the world. Due to their, often, innovative and complex layouts, tall buildings can pose unique challenges to architects and engineers. Previous tall building failures raised significant concerns on the applicability of prescriptive fire design for these structures. The use of structural fire engineering can enhance the safety of a tall building under fire by strengthening any vulnerable areas in the structure and at the same time reduce the costs of fire protection by removing it when unnecessary. Commercial finite element and specialist structural fire engineering software have their advantages and disadvantages. In this thesis, the object-oriented and open-source finite element software OpenSees is presented along with its development with structural fire capabilities by the author and other researchers at the University of Edinburgh. Specifically, new pattern, element, section and material classes have been introduced. All the developed code follows the object-oriented paradigm and is consistent with the ethos of the existing framework. Verification and validation studies of the developed code are also presented. Several procedures including that for dynamic analysis of structures in fire for the collapse assessment of structures are discussed. The development of OpenSees with structural fire capabilities allows the collaboration of engineers across geographical boundaries and disciplines using a community tool. In this work, the behaviour of tall buildings under different fire scenarios has been modelled using the developed OpenSees code. Firstly, the collapse mechanisms of generic tall buildings are investigated, namely the strong and weak floor mechanisms are demonstrated, and criteria are established on when each of these mechanisms occurs. The parametric study performed demonstrated that the weak floor collapse is less probable for generic composite buildings however this type of failure can become easier to appear as the number of floors in fire increase. The effect of vertically travelling fires on these mechanisms is also examined. The results of the study show that slower travelling rates delay or avoid the global failure of a tall building compared to quicker travelling rates allowing for the time required for steel members to regain their strength during cooling to ambient temperature. However, it was seen that higher tensile membrane forces were observed in the floors as the travelling rates increased which could result in possible connection failure. Most of the research and design codes, such as Eurocode, typically assume a uniform thermal environment across the floor area of a structure when defining the design fire. However, in reality fires are more likely to travel in large enclosures, hence there is a need to understand how tall buildings behave under more realistic fire conditions such as travelling fires. A methodology for defining the thermal environment of large enclosures using travelling fires has been recently developed at the University of Edinburgh. Taking into account OpenSees' programmable architecture and its recent inclusion with heat transfer capabilities by other researchers, there was a collaborative effort in order to understand the thermal and structural response of a generic composite tall building under horizontally travelling fires. The findings of the study showed that larger travelling fire sizes produce quicker heating to the steel beams while smaller fire sizes produce higher peak temperatures in the concrete slab. The structural analysis also demonstrated that travelling fires produced higher midspan deflections in comparison to Eurocode parametric fires and higher plastic deformations which is an indication of higher damage. Further work focused on looking at the behaviour of tall buildings under the combined scenario of horizontally and vertically travelling fires. The results of the study showed that the travelling fires produce lower maximum compressive and tensile membrane forces in the composite floor compared to the Eurocode parametric fires for the building examined and thus in a multi-floor scenario the columns are pulling-in less after large deflections develop in the floor. More specifically, the short-hot fire produced the most demanding response. This suggests that in long floors where uniform heating is really impossible, the time of failure predicted by parametric fires in a multi-floor scenario can be more onerous. The outcomes of this work can aid designers when considering the structural fire response of tall buildings in a performance based design context. It was demonstrated that multi-floor fires could be a threat for tall buildings, and thus this possibility should be considered in design. The use of more realistic fire definition for large enclosures, such as travelling fires, should also be considered. The travelling fire methodology can provide an enhanced level of confidence for the safety of a building since it can represent a range of similar fires to those that may occur in a real fire scenario.

Traditional counting of tree rings between fire scars to establish a fire history is examined for a better understanding of factors influencing fire scar formation and wound healing. The problem of dating fires which burn prior to or after the period of cambial activity is emphasized. A methodology for fire history studies based on fire scar and tree-ring analysis developed by Arno and Sneck (1977) is reviewed and elaborated upon. The importance of crossdating, height of sample cross sections, and problems associated with the extrapolation of data are discussed. Ongoing research involving the examination of the mineral concentration of tree rings and the presence of traumatic resin canals as markers of past fires is reviewed.