Modern composite steel frame structures possess a high degree of redundancy. This allows them to survive extreme fires without collapse as there are many alternative loadpaths which can be used to transfer load away from the fire affected part of the structure as demonstrated in the Broadgate fire. Subsequent tests carried out on the Cardington frame showed that it was not necessary to apply fire protection to all steel beams. It was possible to leave selected secondary beams without fire protection. In the event of a fire this results in large deflections due to thermal expansion and material degradation, however, in a fire where servicability requirements do not need to be met this is acceptable so long as life safety is ensured. The weakening beams and large deflections result in a change in the load transfer mechanism with load being carried through tensile membrane action in the slab. This thesis presents a method for calculating the membrane load capacity of composite floor slabs in fire. Extensive numerical modelling at the University of Edinburgh has shown that the temperature distribution through a structural member greatly effects the deflection and pattern of internal stresses and strains. Theoretical solutions were produced to calculate the structural response of laterally restrained beams and plates subject to thermal loads. The theoretical deflections and internal forces were shown to compare well with those from numerical models. To determine the membrane load capacity of concrete floor slabs in fire a three-stage design method was developed. Initially the temperature distribution through the slab was calculated for the design fire. From this the deflection of the slab and resulting stress and strain distributions in the steel reinforcement due to the thermal loads were calculated for the design fire. From this the deflection of the slab and resulting stress and strain distributions in the steel reinforcement due to thermal loads were calculated using equations from the theory developed previously. Failure of the slab was defined based on a limiting value of mechanical strain in the reinforcement, this strain corresponded to a limiting deflection. The load capacity of the slab at the limiting deflection was calculated using an energy method. When compared against results from numerical models the ultimate load capacity was shown to be accurately predicted. None of the fire test carried out on the Cardington structure reached failure. Although demonstrating the inherent strength of such buildings this was also a major short coming as it was not possible to define the point of failure. the design method developed was used to calculate the membrane laod capacity of four of the six Cardington tests. All four tests were shown to have had a significant reserve capacity with none being close to failure.

Examination of the literature reveals a paucity of dedicated research into collisions and groundings involving UK fishing vessels. The aim of this research was to provide answers to fundamental questions regarding the factors that contribute to fishing vessel traffic losses. Data for this study were gathered from a broad range of sources and an eclectic range of techniques employed in their analysis. The recent development of the UK fishing fleet and the pattern of losses from all causes is investigated for the period 1975 to 1994. Fishing vessel collision and grounding losses are then set in relative perspective by comparison with those arising from other causes. Aspects of the macro-environment in which the UK fishing fleet has operated since 1975 are examined and the results interpreted in the form of a comparative regional analysis. The micro-environment prevailing in the fishing fleet is exemplified through combining an array of observations made at sea on board working fishing vessels with questionnaire responses drawn from representative samples of British fishermen in 22 fishing ports around the country. A previously unattempted composite analysis of the circumstances of fishing vessel collision and grounding losses is presented and this allows for a number of conclusions to be drawn. A causal analysis technique is applied to fishing vessel casualties for the first time and leads to the identification of human factors as a more significant contributor to traffic losses than either technical or environmental factors. A novel programme of cross-validated observations of fishing vessel watchkeepers in their working environment was pursued, providing data on how attention is allocated, workload levels at different stages in the fishing cycle and also on the watchkeeper's cognitive state while on duty. The thesis concludes with a wide ranging discussion and recommendations based on the research that could contribute to reducing loss of life and vessels in traffic events, made with due consideration for the physical and fiscal constraints that impinge upon the UK fishing fleet.

Building fire safety is significantly influenced by building and fire safety regulations (often codes and standards). These regulations specify what fire safety measures should be included in a given building as a minimum requirement. Since fire engineers develop fire safety designs based on the regulations, they are often viewed as the primary agents in ensuring the fire safety of buildings. However, their mission often starts with given building design features, such as interior spatial layout, exterior shape, site plan, and so forth, which are mostly determined by architects (or architects). Although architects design buildings within the boundaries of the regulatory requirements, their focus is not generally on fire safety, but more on visual and spatial aesthetics of buildings. These objectives are linked to building form and functionality, which are not subject to the building and fire safety regulations. These objectives can sometimes compete with fire safety objectives in such a way that buildings can be unsafe in certain situations due to unintended effects of building design features on actual fire safety performance. To determine whether a building has design features which work against fire safety performance, evaluation of building fire safety performance must take into account the effects of building design features. If fire safety performance is significantly decreased by building design attributes, additional fire safety measures or modifications of the building design should be incorporated to provide an appropriate level of fire safety performance. While there have been various building fire safety evaluation tools developed over the last forty or so years, none of them comprehensively considers building design features and their associated effects as key performance parameters. In this context, the current study develops conceptual models for fire safety performance assessment in both qualitative and quantitative manners. After scrutinizing previous fire incidents and the building features which contributed to their outcomes, various fire safety performance attributes, including building design features, are identified and cause-effect relationships among the attributes are established. Then, the attributes are organized hierarchically like a tree diagram such that the performance of one upper level attribute is determined by the combined performance of multiple lower level attributes. In this way, the performance of bottom level attributes propagates upward to the upper level attributes. Two tree diagrams are established for the most common fire safety objectives, life safety and property protection. Each attribute in the tree diagrams has two quantified values: performance value and weighting factor. The current study uses three different performance values (0.01, 0.5, and 1) for bottom level attributes representing poor, average and good performance, respectively. In addition, as each attribute can have different contribution to upper level attributes, a weighting factor between 0 and 1 is assigned to each attribute which represent the relative importance. With these two values, the performance value of an upper level attribute is calculated using the weighted sum method (summation of multiplied values of performance value and weighting factor) which is commonly used in the Analytical Hierarchy Process. As the performance of an attributes is a function of specific designs, building uses, occupants, and site conditions, in the first instance, judgments of the fire engineers can be used to assign weights and performance values, but they can also be determined jointly among stakeholders. Generally speaking, the details of attributes for fire safety performance are not determined at once. Rather they are gradually determined as the building design progresses. This means that in early design building design phase, many of the attributes are unknown as well as fire safety performance. Once appropriate information can be provided to architects by fire engineers at each building design phase, it is likely to avoid possible conflicts between design details and fire safety performance. Using the fire safety evaluation model, weak attributes for fire safety performance can be identified and possible make-up strategy and building design approach can be developed in advance. This provides the potential for the collaboration between fire engineers and architects and at the end for increasing building fire safety performance of buildings.

Today, ever changing and advancing techniques of construction are constantly pushing the envelope of structural possibilities in the built environment. Although not new, the concept of Double-Skin Façades (DSF) finds increasing implementation with the advent of sustainable construction, aiming to reduce energy consumption to condition buildings whilst improving indoor air quality. As is the case with the traditional concept of the compartment fire, methodologies and assumptions on which our general understanding of the fire problem is based, did fundamentally not change. Inherently bound to this, is the concept of compartmentalisation, prescribing measures to avoid horizontal and vertical fire spread in buildings. A DSF, most commonly featuring a ventilated cavity between curtain wall and the secondary glass façade at an offset, is prone to drastically alter fire and smoke behaviour once able to enter. Unlike curtain walls, the chimney-like aspect ratio of such façades is able to trap fire and combustion gases within the cavity, potentially compromising the integrity of the building perimeter above the fire. The current approach to this issue tends to focus on using non-combustible construction materials and the installation of sprinkler systems to avoid breakage of window panes in the first place. Another topic of interest is the weak connection between floor slab and curtain wall which can allow vertical fire spread to adjacent floors. Research has also been discussing the use of mullions to deflect the fire plume away from the façade. Even if useful in DSF’s, aesthetics and problems with functionality will most likely prevent mullions from being introduced into the DSF. However, very little relevant research actually investigated the fire-induced flow structure under these conditions so that properly informed design decisions can be made. The project at hand aims to understand hazards to the floors above and below the fire floor by experimentally investigating the governing processes by means of large-scale fire testing and small-scale salt-water modelling (SWM). The gathered data shall serve as a basis to discuss current spandrel and cavity design decisions. Results have been compared in terms of dimensionless numbers and demonstrate complex interactions between DSF cavity width and spandrel height, encouraging a discussion about the need of further research of this topic.

The move towards performance-based design of the fire resistance of structures requires more accurate design methods. An important variable in the fire performance of timber structures is the in-depth temperature distribution, as wood is weakened by an increase of temperature, caused by exposure to high heat fluxes. A proper prediction of temperature profiles in wood structural elements has become an essential part of timber structural design. Current design methods use empirically determined equations for the temperature distribution but these assume constant charring rates, do not account for changes in the heating conditions, and were obtained under poorly defined boundary conditions in fire resistance furnaces. As part of this research project, a series of experimental in-depth temperature measurements were done in wood samples exposed to various intensities of radiant heat fluxes, with clearly defined boundary conditions that allow a proper input for pyrolysis models. The imposed heat fluxes range from 10 kW/cm 2, which generates an almost inert behaviour, to 60 kW/cm 2, where spontaneous flaming is almost immediately observed. Mass loss measurements for all the imposed heat fluxes were also performed. The second part of this project dealt with the modelling of the pyrolysis process, with an emphasis placed on temperature prediction. The main objective was to identify the simplest model that can accurately predict temperature distributions in wood elements exposed to fires. For this, an analysis of the different terms which have been included by several models in the energy equation has been done, by quantifying its magnitude. Five models with different degrees of simplification have been developed. Comparison with the experimental data has shown that a simple and accurate model of temperature profiles must include the rise in the solid sensible heat, the heat transferred by conduction, the heat of moisture evaporation, the heat of pyrolysis reaction and the effect of char oxidation.

An experimental study has been carried out to investigate the effects of buoyancy on smoldering of polyurethane foam. The experiments are conducted with a high void fraction flexible polyurethane foam as fuel and air as oxidizer, in a geometry that approximately produces a one dimensional smolder propagation. The potential effect of buoyancy in the process is analyzed by comparing upward and downward smolder propagation through a series of normal gravity and variable gravity experiments. Both opposed and forward mixed (free and forced) flow smolder configurations are studied. In opposed smolder the oxidizer flow opposes the direction of smolder propagation, and in forward smolder both move in the same direction. Variable gravity free flow tests are also conducted in an aircraft flying a parabolic trajectories that provides low gravity periods of up to 25 sec. Measurements are performed of the smolder reaction propagation velocity and temperature as a function of the location in the sample interior, the foam and air initial temperature, the direction of propagation and the air flow velocity. This information is used in conjunction with previously developed smolder theoretical models to determine the smolder controlling mechanisms and the effect of gravity. Three zones in the fuel sample with clearly defined smolder characteristics are identified. A zone close to the igniter where smolder is affected by the external heat, a zone at the end of the sample where smolder is affected by the environment, and a zone at the end of the sample where smolder is affected by the environment, and a zone, in the middle of the foam, that is free from external effects. This last zone is the most characteristic of one dimensional, self-supported smolder, and the one that is studied in greater detail. In mixed flow convection buoyancy induced flows together with the forced flow are the primary mechanism of oxidizer transport to the reaction zone, while diffusion has a secondary importance. In natural convection, downward smoldering is of the opposed type while upward smoldering resembles more the forward type. For opposed flow smoldering, both natural and forced, the smolder propagation velocity is found to increase with the oxidizer mass flux reaching the reaction zone. This result confirms predictions from previously developed theoretical models that the smolder velocity is proportional to the oxygen mass flow. The experimental data is correlated in terms of a non-dimensional smolder velocity derived from these models, the results show very good agreement between theory and experiments for strong smolder. To implement the models, an analysis of the gas flow field is developed where the effect of significantly different permeabilities between char and foam is been Extinction is observed for very low and for very high flow rates, which shows that smolder is controlled by a sensitive competition between oxygen supply and heat losses to and from the reaction zone. Under these conditions the models do not describe the experiments well. The forward flow smolder experiments show that forward smoldering is controlled not only by the competition between oxygen supply and heat losses to and from the reaction zone but also by the competition between pyrolysis and oxidation. For low flow velocities a regime resembling the opposed flow is observed. As the air flow velocity is increased, foam pyrolysis followed by char oxidation is the controlling smolder mechanism. For both these conditions the theoretical models describe the experiments well. Increasing the flow velocity further results in a smolder propagation velocity controlled by total fuel consumption, in downward burining. For upward burning transition to flaming is observed for very high air flow velocities. This last regime is not well predicted by the theoretical models. The results from the experiments in variable gravity environment conducted in the KC-135A and Leajet airplanes confirm the normal gravity observations that the competition between heat losses and oxidizer transport is the major mechanism controlling smolder. The absence of convective flow in low gravity results in higher temperature in the unburnt fuel and char due to smaller heat losses to the surroundings. However, the oxidizer transport to the reaction zone also decreases and as a result the temperature at the reaction zone decreases indicating a weakening of the eaction, The presence of pyrolytic reactions in foward smolder and their capability to inhibit smoldering complicates the above described smolder mechanisms.

This dissertation presents the results of experimental and computational investigations on the behavior of steel simple beam end framing connections subjected to fire. While significant progress has been made in understanding the overall structural response of steel buildings subject to fire, the behavior of connections under fire conditions is not well understood. Connections are critical elements for maintaining the integrity of a structure during a fire. Fire can cause large force and deformation demands on connections during both the heating and cooling stages, while reducing connection strength and stiffness. Of particular importance are simple beam end framing connections. These are the most common type of connection found in steel buildings and are used at beam-to-girder and girder-to-column connections in the gravity load resisting system of a building. This dissertation focuses on one particular type of beam end connection: the single plate connection, also known as a shear tab vii connection. This connection is very commonly used in U.S. building construction practice. In this study, material properties of ASTM A992 structural steel at elevated temperatures up to 900°C were investigated by steady state tension coupon tests. Experimental studies on the connection subassemblies at elevated temperatures were conducted to understand and characterize the connection strength and deformation capacities, and to validate predictions of connection capacity developed by computational and design models. In the computational studies, a three-dimensional finite element connection model was developed incorporating contact, geometric and material nonlinearity temperature dependent material properties. The accuracy and limitations of this model were evaluated by comparison with experimental data developed in this research as well as data available in the literature. The computational studies investigated the typical behavior of the connection during heating and cooling phases of fires as well as the connection force and deformation demands. The finite element model was further used to study and understand the effects of several key building design parameters and connection details. Based on the test and analysis results, some important finding and conclusions are drawn, and future work for simple shear connection performance in fire are discussed. / text

Wildland fire is a natural part of the earth’s phenomenological pattern and like most natural phenomena has presented a challenge to human activity and engineering science. Wildfire presents Fire Safety Engineering with the task of developing fundamental research and designing analysis tools to address fire on a scale where interactions with atmospheric and terrestrial conditions dominate fire behavior. The research work presented in this thesis addresses a fundamental research issue involving transport processes in porous wildland fuel beds. This research project had the specific goal of developing an understanding of how transport processes affected the combustion of wildland fuels that were in the form of a porous bed. No detailed study could be found in the literature that specifically addressed how the fuel structure affected the combustion process in these types of fuels. To this end, a series of experiments were designed and carried out that approached the understanding of this problem using commonly available fire testing equipment, specifically the cone calorimeter and the FM Global Fire Propagation Apparatus. The goal of this research study and the basis for the novel and relevant contribution to the field of engineering was to conduct an experimental test series, analyze the data and examine the scalability of the results, to determine the effect of transport processes on the Heat Release Rate (HRR) of porous wildland fuels. The project concluded that flow dominates HRR in fires involving the wildland fuels tested. A dimensionless analysis of the fuel sample baskets showed consistency with well established mass transfer, fluid flow and chemical kinetic relationships. The dimensionless analysis also indicates that the experimental results should be scalable to similar configurations in larger fuel beds. One conclusion of this study was that wildland fire modeling efforts should invest in understanding flow conditions in fuel beds because this behavior dominates over the chemical kinetics of combustion for predicting HRR which is an important parameter in fire modeling.

The Department of Building and Housing is currently developing a performance framework that will, if adopted, provide a compulsory methodology for performance based fire engineering designs to prove compliance with the fire safety requirements of the New Zealand Building Code. The conceptual performance framework currently includes eight design fire scenarios, fire loads for particular building uses, and tenability criteria for the life safety of occupants. As the level of fire safety within the Code is not explicit, the Department of Building and Housing determined that the performance framework for fire should ensure buildings are designed and built to provide the same level of safety as if they complied with the current Compliance Document for New Zealand Building Code Fire Safety Clauses, C/AS1. This work analysed 12 buildings with a range of uses, which comply with the current C/AS1, using the conceptual performance framework to provide a risk comparison for life safety. Accepted, previously established calculation and modelling methods were used to test the case buildings to the performance framework. None of the buildings met the pass criteria proposed for life safety. Consequently, to comply with the performance framework, a building would be required to be designed to a higher level of safety than is currently accepted to meet code. This shows the current proposal provides a more onerous design regime for fire safety for buildings than the current C/AS1. The results of this research show the conceptual performance framework for fire safety is not ready to be included into New Zealand building regulations in its present form. Furthermore, protection from fire for primary structural members and systems, to protect against building collapse, and tenability criteria and fire fighting access for fire fighters needs to be developed and included in the framework.

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