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.

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.

<p> Construction safety is an essential aspect of the construction industry and measuring safety performance has been of continuing concern. Most of the preceding studies concentrated on two widely used metrics in industry to evaluate and improve safety performance, EMR and incidence rates. However, it is recognized that these metrics have shortcomings, such as being reactive and not proactive, or representing a macroscopic approach and not microscopic approach, or disregarding the events that lead to accidents and only being result-oriented. Improving safety is one aspect of a research but using an appropriate safety measure is as important. Using these parameters comes with their limitations, and they need to be well understood while drawing conclusions so as not to mislead an owner while comparing companies' safety performance or making a decision to select a safe contractor, the same holds true for the contractor's own management while self-assessing its safety performance and deficiencies. </p><p> This study focused on a new safety performance metric by introducing a proactive safety performance measurement system through observed safety violations of OSHA standards. The new metric, site safety performance value (SSPV) was based on OSHA's Gravity Based Penalty (GBP) system and quantified general contractors' site safety performance to measure their ability to comply with OSHA safety rules and regulations. This metric is a leading indicator based on pre-accident driven data. It was also used to develop a new predictive model to evaluate general contractors' safety performance and examine the relationships between the project and company demographics and the proactive safety measure, SSPV, for advancement of construction safety performance. The statistical model constructed can predict future contractor safety performance, and it may contribute to the contractor selection process. The methodology additionally included an investigation of specific construction trades to find out which trades carry the highest risk in terms of safety and impact construction safety performance the most. </p><p> The findings of this study can be used by numerous groups including the general contractors, owners, safety professionals and researchers to identify where safety performance can be improved, and determine the significant parameters that could help identify the areas of concern by utilizing a new proactive safety performance evaluation system.</p>

<p> Low back pain (LBP) is the most prevalent work-related musculoskeletal disorder. Occupational risk factors have been studied for current ergonomic prevention strategies; however, other underlying mechanisms may exist since not all workers performing the same task develop the same severity. Previous research has identified personal and psychosocial risk factors that also contribute to LBP. Research quantifying the interactive effects of the various personal, psychosocial and occupational factors is limited, along with research on the effect of risk factor combinations on LBP severity. </p><p> The objectives of this study were to: 1) study the various factors that are known to be involved in low back pain and analyze interactions, and 2) develop a model to predict low back pain and validate it. In order to address these objectives, 2 studies were conducted. </p><p> The first study investigated the effects of various personal, genetic, occupational and psychosocial factors on two subjective LBP severity ratings: Oswestry Disability Index (ODI) and a Visual Analog Scale (VAS), and three physician-based ratings: MRI severity, canal stenosis and nerve impingement. Personal and psychosocial factors, in addition to occupational factors, were found to significantly affect the severity ratings. </p><p> The second study involved building predictive models of LBP severity for each risk factor category as well as a combined risk factor model. Results showed that the combined risk factor models considering interaction effects both within and across risk factor categories were significantly better in predicting severity ratings than the individual models. However, validation conducted using 5 random samples showed inconsistent accuracies. Results obtained may help to develop a more reliable way to predict and, hence, prevent chronic LBP.</p>

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.

One of the challenging problems in the aerospace industry is to design an automated 3D vision system that can sense the installation components in an assembly environment and check certain safety constraints are duly respected. This thesis describes a concept application to aid a safety engineer to perform an audit of a production aircraft against safety driven installation requirements such as segregation, proximity, orientation and trajectory. The capability is achieved using the following steps. The initial step is to perform image capture of a product and measurement of distance between datum points within the product with/without reference to a planar surface. This provides the safety engineer a means to perform measurements on a set of captured images of the equipment they are interested in. The next step is to reconstruct the digital model of fabricated product by using multiple captured images to reposition parts according to the actual model. Then, the projection onto the 3D digital reconstruction of the safety related installation constraints, respecting the original intent of the constraints that are defined in the digital mock up is done. The differences between the 3D reconstruction of the actual product and the design time digital mockup of the product are identified. Finally, the differences/non conformances that have a relevance to safety driven installation requirements with reference to the original safety requirement intent are identified. The above steps together give the safety engineer the ability to overlay a digital reconstruction that should be as true to the fabricated product as possible so that they can see how the product conforms or doesn't conform to the safety driven installation requirements. The work has produced a concept demonstrator that will be further developed in future work to address accuracy, work flow and process efficiency. A new depth based segmentation technique GrabcutD which is an improvement to existing Grabcut, a graph cut based segmentation method is proposed. Conventional Grabcut relies only on color information to achieve segmentation. However, in stereo or multiview analysis, there is additional information that could be also used to improve segmentation. Clearly, depth based approaches bear the potential discriminative power of ascertaining whether the object is nearer of farer. We show the usefulness of the approach when stereo information is available and evaluate it using standard datasets against state of the art result.

The ability to predict the temperatures in protected steel structures is of vital importance for the progress of fire safety engineering. Existing methods are limited in several respects, typically being computationally restricted and limited to examination of the performance of specific components. This thesis investigates a generalised CFDbased methodology for thermal analysis of structural members in fire, developed to overcome these limitations. A novel methodology has been developed, known as GeniSTELA (Generalised Solid ThErmal Analysis), which computes a “steel temperature field” parameter in each computational cell. The approach is based on a simplified 1D model for heat transfer, together with appropriate corrections for 2D and 3D effects, to provide a quasi- 3D solution with a reasonable computational cost. GeniSTELA has been implemented as a submodel within the SOFIE RANS CFD code. The basic operation of the model has been verified and results compared to the empirical methods in EC3, indicating a satisfactory performance. The role of the surface temperature prediction has been examined and demonstrated to be important for certain cases, justifying its inclusion in the generalised method. Validation of the model is undertaken with respect to standard testing in fire resistance furnaces, examining the fire ratings of different practical protection systems, and the BRE large compartment fire tests, which looked at protected steel indicatives in full-scale post-flashover fires; in both cases, a satisfactory agreement is achieved. Model sensitivities are reported which reveal the expected strong dependencies on certain properties of thermal protection materials.

No description available.

In today’s Nordic construction industry, it is difficult for new and innovative building solutions to be introduced due to prescriptive and inflexible regulations. Trading products and services cross-border is something that could loosen the tough market, but this is not possible due to the lack of common international frameworks that is performance based with the possibility to perform fire safety engineering. This is something that the Nordic Innovation project group called Fire Safety Engineering for Innovative and Sustainable Building Solutions wants to change. By introducing a new probabilistic method to verify fire safety in buildings, with the intention to become a Nordic standard, so will hopefully parts of these problems be resolved. The fourth work package of the project includes field testing of the new method which this thesis is a part of. The idea is to asses and improve the new probabilistic approach by comparing it to an existing non-probabilistic method and introduce ameliorating recommendations. Comparison of the probabilistic method is performed against a Swedish verification process that’s based on the General recommendations on analytical design of fire safety strategy (BBRAD) by verifying fire safety in a car park, that is located below an office building, with both verification methods. The two performance-based analyses treat deviations from a prescriptive solution, performed with the Boverket’s Building Regulations (BBR), and the results of these verifications is compared. The requirements that is verified are; escape in event of fire, protection against the outbreak of fire, protection against the development and spread of fire and smoke in buildings, protection against spread of fire between buildings, possibility of rescue responses and ensuring fire resistance in the structural members. Fire safety designs and approaches for treatment of the deviations are compared and analysed which concludes in the improvement recommendation that’s been presented.  Questions that has been answered during the work process is: How do the methods treat the possibility of a fire safety design without sprinkler? What is the main difference between the two verification methods? Which improvements could be done to the new Probabilistic method?  The recommendations of improvement that has been presented is based on the work process of the probabilistic approach and the comparison with the Swedish verification process. Development of the following areas is advocated: Treatment of critical levels for evacuation scenarios  Form a common Nordic statistical database Improved guidance of how to complete the validation analysis The thesis does not include all parts that’s required in a fire safety design but will merely focus on the deviations of the pre-accepted solution. The verification is only performed on the car park, i.e. the office part of the building is not included. / I dagens nordiska byggbransch är det svårt för nya och innovativa byggnadslösningar att införas på grund av de preskriptiva och fyrkantiga regelverk som finns. Handel av produkter och tjänster över gränserna är något som kan luckra upp den tuffa marknaden, men det är svårt på grund av bristen utav gemensamma internationella regelverk som är funktionsbaserade med möjlighet till fire safety engeinnering. Det är något som ett nordiskt innovationsprojekt kallat Fire Safety Engineering for Innovative and Sustainable Building Solutions vill förändra. Genom att införa en ny probabilistisk metod för att verifiera brandsäkerheten i byggnader, med avsikten att skapa en nordisk standard, kan förhoppningsvis delar av dessa problem lösas. Det fjärde arbetspaketet inom projektet består av att testa den nya metoden, vilket denna avhandling är en del av. Tanken är att bedöma och ta fram förbättringsförslag till den nya probabilistiska metoden genom att jämföra den med en befintlig scenariobaserad metod och presentera förbättringsrekommendationer. Jämförelse av probabilistiska metoden utförs mot en svensk verifieringsprocess som baseras på Boverkets allmänna råd om analytisk dimensionering av byggnaders brandskydd (BBRAD) genom att verifiera brandsäkerheten i ett parkeringsgarage, som ligger under en kontorsbyggnad, med båda verifieringsmetoderna. De två funktionsbaserade analyserna behandlar avvikelser från en förenklad dimensionering, som är utförd enligt Boverkets Byggregler (BBR), och resultaten av dessa verifikationer jämförs. De krav som verifieras är; utrymning i händelse av brand, skydd mot uppkomst av brand, skydd mot utveckling och spridning av brand och rök i byggnader, skydd mot brandspridning mellan byggnader, möjlighet till räddningsinsats och att säkerställa bärförmåga vid brand. Brandskyddets utformning och metodernas behandling av avvikelserna jämförs och analyseras vilket konkluderar i de rekommendationer för förbättring som presenteras. Frågor som har besvarats under arbetsprocessen är: Hur behandlar metoderna möjligheten att dimensionera brandsäkerheten utan sprinklersystem? Vad är den stora skillnaden mellan de två verifieringsmetoderna? Vilka förbättringar kan göras på den nya probabilistiska metoden? Rekommendationerna till förbättring som har tagits fram är baserad på arbetsprocessen i den probabilistiska metoden och jämförelsen med den svenska verifieringsprocessen. Utveckling av följande områden förespråkas: Behandling av kritiska nivåer i utrymningsscenarion Uppställning av en gemensam statistiskdatabas för de nordiska länderna Förbättrad förklaring om hur man utför valideringarna av analysen Avhandlingen omfattar inte alla delar som behövs vid bandskyddsprojektering utan fokusera endast på avvikelserna från den förenklade dimensioneringen. Verifikationen är endast utförd på parkeringsgaraget, det vill säga kontorsdelen av byggnaden behandlas inte. / Fire Safety Engineering for Innovative and Sustainable Building Solutions