Piotr Tofiło a,*, Marek Konecki b, Jerzy Gałaj c, Waldemar Jaskółowski d, Norbert Tuśnio e, Marcin Cisek f

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1 Available online at Procedia Engineering 57 (2013 ) th International Conference on Modern Building Materials, Structures and Techniques, MBMST 2013 Expert System for Building Fire Safety Analysis and Risk Assessment Piotr Tofiło a,*, Marek Konecki b, Jerzy Gałaj c, Waldemar Jaskółowski d, Norbert Tuśnio e, Marcin Cisek f a,b,c,d,e Faculty of Fire Safety Engineering, The Main School of Fire Service, Słowackiego st. 52/54, Warsaw, Poland f Faculty of Civil Safety Engineering, The Main School of Fire Service, Słowackiego st. 52/54, Warsaw, Poland Abstract The paper contains a description of an expert system for risk assessment and fire risk analysis in buildings, which is currently being developed in SGSP. The creation of such a system is dictated by the needs of the communities of fire protection designers, specialists and verification bodies for a clear and easily accessible tool that will be further developed as needed in order to support and improve the national design and construction process for fire safety engineering. The system offers the following parametric modules: the geometry of the building, the fire size, convection column, smoke generation, detection, ventilation, evacuation, intervention, construction, criteria for sensitivity and risk The The Authors. Authors. Published Published by Elsevier by Ltd. Elsevier Ltd. Selection and peer-review under responsibility of the Vilnius Gediminas Technical University. Selection and peer-review under responsibility of the Vilnius Gediminas Technical University Keywords: risk analysis; fire hazards; risk; ventilation; evacuation; fire service intervention. 1. Introduction In building fire safety engineering we have now a rapid growth in the use of modern computational methods and applications. It is increasingly associated with the opening of our country's philosophy of "performance based design" aimed at achieving design-oriented or functional purposes or as it is often called according to the technical principles. Field of fire safety engineering is a relatively young field, and in many aspects it has not yet established routines and widely accepted standard solutions. Of course there are standards such as NFPA and BS that contain large amounts of structured knowledge, such as rules for calculating certain parameters of fire hazard for various building configurations, but these rules are often too rigid and thus insufficient. Therefore, increasing the use of more complex methods that take the form of sets of equations, engineering correlations and computer models of varying complexity. The number of available computer models become so significant that the big problem is the issue of verification of calculations performed using them. Access to the best and most complex programs is often limited by their high cost. Another significant factor is the problem of taking the input data for calculations. This data is often collected from various sources, which often do not have sufficient reliability. These factors mean that the verification requires a lot of experience, expertise, knowledge of tools, regulations and foreign standards, technical literature and often foreign languages. Unfortunately, access to these materials and skills to gain experience is often difficult for a wide audience. In the current situation a need gradually emerges for free access expert systems, which would allow for multi-level analysis of problems related to fire safety. So far, tools for fire safety analysis were created mainly abroad. This paper will discuss the vision and a prototype of an expert system being developed. It is addressed to individuals interested in performing calculations associated with the development of fire in buildings, evacuation of people, fire service interventions and structural safety. The system will offer easy access to input data customized for different types of buildings. It will offer a deterministic approach and also analysis based on the probabilistic criteria and risk. * Corresponding author. address: [email protected] The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of the Vilnius Gediminas Technical University doi: /j.proeng

2 Piotr Tofi ło et al. / Procedia Engineering 57 ( 2013 ) The advantage of such an approach to the issue of fire safety engineering in the design and verification process is potentially a more uniform level of analysis and expertise, enabling efficient verification and creation of reference models that can be considered by the competent authority as acceptable as a minimum in the same way as prescriptive rules are now. The expert system will be partially or completely implemented on a web platform developed by SGSP during the course of a project funded by NCBiR. Fig. 1. General view of the system. A data input pane on the left and the data presentation pane on the right. Change of grouped input data and data presentation is done using tabs 2. Modules of the system Currently system includes the following modules, which are discussed below. 3. Geometry of the problem (building) This is the module where the user sets the scope of the problem in terms of a possible mode of development and its impact on the evacuation of the building. In the largest number of real-world problems solved by engineers, the situation can be narrowed down to the development of a fire in a single space or a room or a maximum of two rooms which are crucial for the analysis. Altogether, the fire and evacuation problem may include another adjoining room. This simplified approach allows analysis of a large number of actual situations, and it should be emphasized that the purpose of the system is not to duplicate the capabilities of other, more complex programs. The user after the selection of geometry option (one or two rooms) has the choice of geometric parameters such as the areas and height of rooms. In the future, the ability to define a variable cross-sectional area will be added. 4. Fire size (HRR) This module is used to define the fire development curve (HRR curve). To this end, the user may use: a) alpha coefficient; b) one of the available curves of the system databases. These curves are standard curves or curves resulting from experiments; c) factor alpha or curve associated with the selected type of compartment (building). Association of factors and curves makes it possible to fix parameter assignment to the nature of the premises, which prevents the use by inexperienced users too optimistic values of key parameters that describe a fire hazard. At the same time it enables faster verification of the assumptions of the analysis carried out by the user. The development of a fire in terms of quantity of heat generated may be limited by the geometry of the room or by the activation of fire extinguishing systems. The user can specify a maximum HRR to limit the size of fire or a maximum value can be set by the use of the sprinkler in detection module.

3 1158 Piotr Tofi ło et al. / Procedia Engineering 57 ( 2013 ) Convective fire plume Fig. 2. Fire size module Different spatial configurations require different modes for calculating convection column and the amount of smoke entering the hot layer. The user can select the following plumes: a) axisymmetric (two variants, depending on the height of the smoke layer); b) the spill plume (in the variant with side curtains or without); c) window plumes. The user should select the type of column according to the problem considered. In addition to plume types, the user can define the height of the fuel base and the parameters defining the heat loss associated with the radiation zone of the flames and the heat transfer to the walls. 6. Smoke generation Parameters of the combusted fuel affect the composition and amount of the combustion products and soot particles in the smoke layer, which in turn affects the visibility distance, the detection of smoke and toxicity of fire environment. Key parameters which are currently considered in this module are: a) the heat of combustion; b) combustion efficiency; c) mass production of smoke; d) the mass optical density of the smoke. As in the case of fire size, the user can: a) define the parameters of the fuel itself; b) choose a material from the database; c) select the type of room / building from the database. Selecting the type of building is once again an option that frees the user from making a decision regarding specific parameters of combustion materials. 7. Detection Fire and smoke detection can be achieved through the use of heat detectors (heat detectors, sprinklers) and smoke detectors (detector point and linear). The user can use the detection time calculated in this module as input information in other modules.

4 Piotr Tofi ło et al. / Procedia Engineering 57 ( 2013 ) Smoke control Fire ventilation systems have a large impact on the environment of fire, especially in the temperature of the smoke layer and its height. The user can choose a system of natural or mechanical ventilation or decide for a complete lack of ventilation. In this case, the user can check if ventilation is needed. Defining the parameters of natural ventilation system, the user can decide about the area of vents and air inlets compensation and the aerodynamic coefficients of these two types of openings. In the case of mechanical ventilation extract, the user can specify the intensity of smoke extraction in m 3 /s and the parameters that determine whether or not there is a so-called plugholing i.e. extraction of air from lower layer. 9. Evacuation Evacuation module contains all the parameters that determine the RSET time. These are the times of detection, alarming, people's reactions, widths of exits and length of the travel distance. Reaction and recognition times (pre-movement) can be entered manually or indirectly by selecting the type of building and its management, alerting and complexity categories. Again, the system helps the user in this way to avoid the uncertainty associated with not knowing values from a standard or literature. 10. Fire service intervention Fig. 3. Evacuation module Fast response time of fire brigade is a positive factor affecting the development of a potential fire and building construction, and the knowledge of the probable time of the fire brigade intervention is important information that can sometimes affect the result of the fire safety analysis. Therefore, the user can quickly determine the expected time of arrival and the start of operations by the local State Fire Service. For this purpose a database is used with coordinates all State Fire Service stations in the country and the algorithm for calculating travel time from point A to point B, provided by Google. The user can also quickly get a map with the visualization of the route from the nearest station to the fire.

5 1160 Piotr Tofi ło et al. / Procedia Engineering 57 ( 2013 ) Fig. 4. Intervention module Fig. 5. Route from the nearest fire station to the designed building 11. Criteria This module is used to determine the criterion or set of criteria that is taken into account in determining the available safe evacuation time. The user can set a criterion such as the height of the smoke layer, the temperature, visibility and a critical level of toxicity. This list may be extended to carbon monoxide. 12. Sensitivity Sensitivity module is designed as an auxiliary tool through which users can explore the impact of a particular input parameter variability on the distribution of the output values, mainly Available Safe Evacuation Time. The user has the ability to identify the parameters of the highest importance and impact on the final result. The importance of this module is mainly related to information and education. Fig. 6. Input data sensitivity module

6 Piotr Tofi ło et al. / Procedia Engineering 57 ( 2013 ) Fig. 7. Sensitivity of input data variation of ASET as a function of the specified range of alpha parameter 13. Risk Risk module allows for probabilistic analysis in which the user defines the statistical distributions of key input parameters, and the system will use the Monte Carlo method to calculate the statistical distributions of RSET and ASET times, which can be used as a more appropriate means of analysis in the field of fire safety engineering in a situation of uncertainty of the input parameters. Monte Carlo method consists of performing a large number such as 1000 or more simulation runs, where data for each run is drawn according to the user-defined distributions. Result of the work of this module is presented in a bar graph representing the distribution of both analyzed times. Their position or degree of penetration can be used as a measure of risk.

7 1162 Piotr Tofi ło et al. / Procedia Engineering 57 ( 2013 ) Presentation of results Fig. 8. Visualisation of risk data graph showing probability distributions for particular RSET and ASET times The results of the calculations are presented in an interactive way by a group of graphs showing key parameter histories plus statistical distributions associated with the risk analysis and sensitivity analysis. Below are shown examples of graphs from the module output. Vertical and horizontal lines visible on the graph denote: a) the value of the criteria (for example, height of the layer, temperature) and the calculated time when these values are exceeded; b) RSET and ASET times; c) time of intervention.

8 Piotr Tofi ło et al. / Procedia Engineering 57 ( 2013 ) Fig. 9. The graph showing the height of the smoke layer

9 1164 Piotr Tofi ło et al. / Procedia Engineering 57 ( 2013 ) Fig. 10. The graph showing the temperature of the hot layer Fig. 11. The graph showing the evacuation history

10 Piotr Tofi ło et al. / Procedia Engineering 57 ( 2013 ) Parameter database The database contains a set of parameters that can be used in the calculation. These are: a) data specific to the type of premises and buildings alpha coefficients, typical characteristics of combustible materials and population profiles; b) the thermophysical data on combustible materials; c) the fire development curves and the experimental fire curves; d) the geographic units of the fire brigade. Fig. 12. General view of the database References [1] BS 7974:2001 Application of fire safety engineering principles to the design of buildings. Code of practice. [2] Jones, W. W., Peacock, R. D., Forney, G. P., Reneke, P. A., CFAST Consolidated Model of Fire Growth and Smoke Transport (Version 6) Technical Reference Guide, NIST Special Publication 1026.