Statistical Determination of Ignition Frequency of Structural Fires in Different Premises in Finland

Ignition frequencies and ignition frequencies per floor area were determined for different building categories in Finland as total groups and as a function of the floor area of the building. These frequencies are needed as input for risk analysis using performance based fire safety design. It was found that differences between building categories or location within country were so small that a universal curve for the whole country could be determined. For ignition frequency per floor area for small buildings a strong dependence on size is observed, but it remains approximately constant for larger buildings. Additionally periodical variations of ignition frequency of buildings by month and week of year, day of week, and time of day were determined. Historical review of the development of ignition frequency models was made. Some evaluation on the generality of the results was made based on the theoretical models.     

A note on estimation of intensities of fire ignitions with incomplete data

Occurrences of fire ignitions in a given region during a specified period of time are modelled as outcomes of a Poisson point process. The ignition frequency is considered a function of the total floor area of the building. Parameter estimates and their uncertainties are computed. Different criteria for model selection are used. The proposed methodology is specifically useful in the case with small data sets or lack of information about the population at risk.     

Aspects of stochastic modeling for structural firesafety

A brief review is presented of methods for stochastic modeling of fires of sufficient severity to threaten the, structural safety of buildings. Information is provided on the rate of fire occurrences according to the floor area at risk for the major occupancy types. National Bureau of Standards Center for Fire Research     

Modelling the evacuation of a high-rise office building in Istanbul

The use of advanced computer models for the analysis of evacuation problems in buildings under fire conditions or terrorist attacks has become an increasingly important research area. Until recently, most safety considerations regarding the evacuation of a building are taken on the basis of some deterministic rules prescribed in fire codes. However, these rules and design principles may not be sufficient to explain the complex interaction between a vast numbers of variables affecting the evacuation process. Also, the characteristics of a fire can differ from building to building and occupants can demonstrate distinctly different behavioural patterns and physiological characteristics. As a result, potential weaknesses, particular to the investigated building, can go unnoticed which, in turn, may result in disastrous consequences during an emergency. The study concentrates on two issues: firstly, what methodology should be pursued to accurately model an evacuation problem and the derivation and extent of parameters needed to fully utilise the potentials of the advanced computer models, in this case, the buildingEXODUS; the second issue is an investigation of the evacuation behaviour in a high-rise office building in Istanbul. It is found that exit knowledge and the preferences of occupants can severely slow down the evacuation process. Fires closer to the ground floor increase the death toll significantly. Failure in the activation of the sprinkler system or the absence of the system altogether can have disastrous effects on the loss of life.     

大型公共建筑火灾研究与探讨

大型公共建筑的突出特点是内部空间大、容纳人数多、疏散困难 ,因此成为火灾事故防范的重点对象。针对大型公共建筑防火设计存在的诸多问题 ,借鉴国内外的研究经验 ,探讨我国大型公共建筑性能化防火设计的研究方向     

Capacity reduction and fire load factors for LRFD of steel columns exposed to fire

Capacity reduction and fire load factors corresponding to the load and resistance factor design (LRFD) format are developed for steel columns exposed to fire. A sample deterministic framework to determine fire and steel temperatures and the capacity of steel columns is adopted for this analysis to structure the methodology. A specific number of parameters that affect the structural response, including the fire load, ratio of floor area to the total area of the fire compartment, opening factor, thermal absorptivity of compartment boundaries, thickness, density and thermal conductivity of insulation, dead load, and live load are taken as random variables. Mechanical and sectional properties of steel (e.g., yield strength, cross-sectional area, etc.), are also considered to be random variables. The effect of active fire protection systems (e.g., sprinklers, smoke and heat detectors, fire brigade, etc.), in reducing the probability of occurrence of a severe fire is included. Given the choice of framework and based on detailed reliability analyses, it is shown that the capacity reduction and fire load factors should vary depending on the presence of active fire protection systems in a building.     

火灾下钢结构楼板的薄膜作用

通过对真实火灾中的足尺火灾试验和观察显示，合组合楼板和承载钢梁的建筑物的结构承载力比现行杭大设计方法的建议值高出许多。因此规范中规定所有承载钢梁都要添加被动防火保护是不必要的。现行设计方法和实际结构性能之间产生这种差异是由于设计方法中忽略了楼板的薄膜作用。本根据国外有关资料给出了几种简单计算方法，允许在钢结构杭大设计中考虑楼板的薄膜作用。从而可以更精确地评估火灾下建筑物的真实承载能力，在给定的耐火时间内能减少相当数量钢梁的防火保护。     

The timing of vegetation fire occurrence in a human landscape

Vegetation fires in urban and peri-urban (human) landscapes damage property and infrastructure, threaten lives and incur considerable suppression costs. This study investigated the timing of fires burning in vegetation within and around the city of Perth, Western Australia. The timing of fires from 16 different cause types were investigated at hourly, daily, monthly and annual scales, and using fire danger indices and fuel moisture. Ignitions from most causes were shown to have hourly and monthly profiles that reflect fire danger and fuel availability. Some causes with low heat outputs, such as cigarettes and sparks from cutting and welding, were more sensitive to fire danger and fuel availability than others. Causes related to arson and recreational activities, such as camp fires, were more likely to occur on weekends and public holidays. Arson prevention measures appear to have reduced the incidence of deliberately lit fires, and may have reduced the number of fires occurring on days of total fire ban, although these days have much higher rates of ignition than other days. High profile fire events also increase public awareness and reduce ignition rates. Lessons learned from analyses of fire occurrence can help fire agencies more effectively apply prevention and mitigation programs.     

Data-driven probabilistic post-earthquake fire ignition model for a community

Fire following earthquake (FFE), a cascading multi-hazard event, can cause major social and economical losses in a community. In this paper, two existing post-earthquake fire ignition models that are implemented in Geographic Information System (GIS) based platforms, Hazus and MAEViz/Ergo, are reviewed. The two platforms and their FFE modules have been studied for suitability in community resiliency evaluations. Based on the shortcomings in the existing literature, a new post-earthquake fire ignition model is proposed using historical FFE data and a probabilistic formulation. The procedure to create the database for the model using GIS-based tools is explained. The proposed model provides the probability of ignition at both census tract scale and individual buildings, and can be used to identify areas of a community with high risk of fire ignitions after an earthquake. The model also provides a breakdown of ignitions in different building types. Finally, the model is implemented in MAEViz/Ergo to demonstrate its application in a GIS-based software.