Multi-compartment Buildings Research Articles

Real-time flashover prediction model for multi-compartment building structures using attention based recurrent neural networks

This paper presents the development of an attention based bi-directional gated recurrent unit model, P-Flashv2, for the prediction of potential occurrence of flashover in a traditional 111 m2 single story ranch-style family home. Synthetic temperature data for more than 110 000 fire cases with a wide range of fire and vent opening conditions are collected. Temperature limit to heat detectors is applied to mimic the loss of temperature data in real fire scenarios. P-Flashv2 is shown to be able to make predictions with a maximum lead time of 60 s and its performance is benchmarked against eight different model architectures. Results show that P-Flashv2 has an overall accuracy of ∼ 87.7 % and ∼ 89.5% for flashover predictions with a lead time setting of 30 s and 60 s, respectively. Additional model testing is conducted to assess P-Flashv2 prediction capability in real fire scenarios. Evaluating the model again with full-scale experimental data, P-Flashv2 has an overall prediction accuracy of ∼ 82.7 % and ∼ 85.6 % for cases with the lead time of setting 30 s and 60 s, respectively. Results from this study show that the proposed machine learning based model, P-Flashv2, can be used to facilitate data-driven fire fighting and reduce fire fighter deaths and injuries.

Smoke and evacuation modelling of multi-compartment building for nuclear applications

Smoke and evacuation modelling of multi-compartment building for nuclear applications

Dynamical source term estimation in a multi-compartment building under time-varying airflow

In the case of an airborne contaminant release, it is critical to know the source location and emission rate as soon as possible and take proper actions to ensure the safety of people. In practice, the source emission rates and airflows in buildings are always time-varying. However, the existing algorithms are not effective for estimating the dynamical source term under time-varying airflow. This study proposed a synthetic inverse model to determine the source location and dynamical emission rates under time-varying airflow in multi-compartment buildings. For this model, a transient Markov chain was built on the basis of the airflow; Tikhonov regularization and Bayesian inference were used to estimate the source emission rate and backward location, respectively. We further investigated the effects of the sensor location selection and regularization parameter selection method (L-Curve, generalized cross-validation (GCV), quasi-optimality (Quasiopt)). The results show that the Markov chain combined with Regularization and Bayesian inference model (MCRB) was feasible for estimating the periodic source term under time-varying airflow, and the relative errors were generally smaller than 20%. The number of time nodes below the threshold (relative error is 20%) of the GCV method accounted for 75.1% of the total number of nodes, the ratio of L-Curve method was 66.8%, and that of Quasiopt method was 57.4%, so the GCV regularization method was preferable to determine the regularization parameter. This study found a new and fresh perspective for source term estimation under time-varying airflow in buildings.

Durability of Buildings in Urban Environment

The longevity forecast is proposed to be implemented on the basis of models of degradation theory. The theory of degradation is developed as a general energy method for estimating the longevity of objects. It is based on the law of conservation of energy. To analyze the longevity of urban environment, it is proposed to adopt the simplest model of theory of degradation. The proposed work provides an explanation for the description of proposed model. The urban environment is divided into a number of simpler systems. The more the degree of system separation into simpler ones, the more accurately one can describe the behavior of the entire system in time. Each simple system is described by the simplest model of degradation theory. The general behavior of the system is understood as a simple sum of individual degradation models. A feature of the proposed theory is that the simplest model can describe the entire system or the sum of its individual parts at once. The model makes it possible to consider the issue of equalizing the longevity of individual systems. The analysis of durability of a multicompartment building is taken as an example. In terms of analyzing the given example, individual stages of systems operation, that are still subject to discussion, are identified.

Planning and management of urban environment using the models of degradation theory

Urban systems are the most complex multi-level objects. The construction and design of such systems is preceded by their analysis and deep study. The article considers the issue of long-term planning of urban systems. The planning is based on the forecast of evaluation of buildings, structures and other urban systems durability. The longevity forecast is proposed to be implemented on the basis of models of degradation theory. The theory of degradation is developed as a general energy method for estimating the longevity of objects. It is based on the law of conservation of energy. To analyze the longevity of urban environment, it is proposed to adopt the simplest model of theory of degradation. The proposed work provides an explanation for the description of proposed model. The urban environment is divided into a number of simpler systems. The more the degree of system separation into simpler ones, the more accurately one can describe the behavior of the entire system in time. Each simple system is described by the simplest model of degradation theory. The general behavior of the system is understood as a simple sum of individual degradation models. A feature of the proposed theory is that the simplest model can describe the entire system or the sum of its individual parts at once. The model makes it possible to consider the issue of equalizing the longevity of individual systems. The analysis of durability of a multicompartment building is taken as an example. In terms of analyzing the given example, individual stages of systems operation, that are still subject to discussion, are identified.

A simplified mathematical approach for modelling stack ventilation in multi-compartment buildings

A simple mathematical model of stack ventilation flows in multi-compartment buildings is developed with a view to providing an intuitive understanding of the physical processes governing the movement of air and heat through naturally ventilated buildings. Rules of thumb for preliminary design can be ascertained from a qualitative examination of the governing equations of flow, which elucidate the relationships between ‘core’ variables – flow rates, air temperatures, heat inputs and building geometry. The model is applied to an example three-storey office building with an inlet plenum and atrium. An examination of the governing equations of flow is used to predict the behaviour of steady flows and to provide a number of preliminary design suggestions. It is shown that control of ventilation flows must be shared between all ventilation openings within the building in order to minimise the disparity in flow rates between storeys, and ensure adequate fresh air supply rates for all occupants.

The quantitative investigation on people's pre-evacuation behavior under fire

With the growth in urbanization process and activities in Hong Kong and many large cities in China, a great number of super high-rise buildings have been constructed in these years. The occurrences of many large fire tragedies, especially the US 9/11 terrorist attack, made people aware that super high-rise buildings may cause serious fatalities, and extremely they could collapse in a huge uncontrolled fire. Compared with people's evacuation behavior, little interests have been drawn to pre-movement behavior. In Hong Kong and some major cities in China, over 90% of people are living in multi-storey multi-compartment buildings. Their awareness and responses to fire incidents happening in the other parts of the same building have substantial influence on the whole evacuation process. Studies on pre-evacuation human behavior have been performed for many years, but the vast majority of the studies were qualitative-oriented. Accordingly, an attempt was made in this article to quantitatively investigate people's pre-evacuation behavior by using the Support Vector Machine (SVM) approach, which was trained by Hong Kong's post-fire field survey data.

The Effect of Pre-movement Time and Occupant Density on Evacuation Time

The effect of occupant pre-movement time and occupant density on evacuation time is presented in this article. Two hypothetical scenarios, a simple room and a multi-compartment building, are presented as building environment. The occupant pre-movement time, an important component of the evacuation time in buildings, follows probability distribution. It is characterized by normal distribution to study its effect on evacuation time for different occupant densities. Moreover, when pre-movement time is characterized by explicit values, the effect of pre-movement time on evacuation time is also studied. Probability distribution of the total evacuation time is also studied under different pre-movement times characterized by normal distributions. Based on congestion and queue analysis, some phenomena of simulation results are interpreted theoretically.

On numerical comparison of enclosure fire in a multi-compartment building

This paper reports a validation study of a CFD simulation for an enclosure fire in a single level multi-room building. Model predictions are compared against measured data of Luo and Beck (Fire Safety J 23 (1994) 413). The CFD-based fire model focuses on the use of laminar flamelet approach to account for the combustion of fire. Global radiation in the multi-compartment building is evaluated though the discrete ordinates method (Combust. Sci. Technol. 59 (1988) 321). Soot model proposed by Syed et al. (Proceedings of the 23rd Symposium on Combustion, The Combustion Institute, 1990. p. 1533) that accounts for the essential physical processes of nucleation, coagulation, surface growth and oxidation is utilised to predict the soot formation and burnout. The presence of soot augmenting the global radiative heat exchange was considered. Overall, our results are in good agreement with the experimental data of Luo and Beck's and also consistent with their numerical results.

Modeling of Hydrogen Flame Propagation in Multicompartment Buildings

A model describing the propagation of buoyancy-driven flames and accelerated jet flames in a multicompartment building has been developed for lumped-parameter containment analysis codes. The model mimics the growth of flame fronts as observed from flame visualization experiments at Pisa University and captures the jet ignition phenomena observed in experiments at the Battelle Model Containment. The model establishes a complete scheme of flame propagation consisting of five flame modes, a fireball, a bubble, a prism, a spherical jet, and a planar jet. Through a flame transformation algorithm, flame propagation in a multicompartment system can be described by a birth and rebirth of these flame modes as many times as necessary until burning is complete. The model was implemented into the MAAP4 code. Comparison of the model prediction with Battelle’s hydrogen test data (test H5) shows good agreement between the model and the experiment. The model correctly predicts the timing of jet ignition and the magnitude of pressure loads in the downstream compartment. The model was developed for the analysis of hydrogen deflagrations in any compartmentalized building including a reactor containment.

Toxic product yields and hazard assessment for fully enclosed design fires

Fires in multi-compartment buildings often occur in enclosed spaces or in enclosures opening into other rooms or corridors. Where such fires occur in relatively small enclosures, with limited external venting, the growth of the fire itself remains restricted. If large vents are present opening into large enclosed spaces or to the outside, flashover may occur. In either case these fires are likely to become oxygen vitiated, producing large amounts of smoke and toxic products. Fire-retarded (FR) and non-FR materials behave differently in these situations from the well-ventilated conditions in most standard tests, with smaller differences in toxic product yields. The main hazard to building occupants is the rapid contamination of building spaces by toxic smoke. Visual obscuration and irritancy of smoke impedes escape efficiency, affecting escape behaviour and slowing travel speeds. This may be followed by incapacitation, primarily due to exposure to asphyxiant gases (mainly CO and HCN), and death. A series of full-scale fire tests conducted in enclosed test rigs and buildings is reported, in which detailed measurements of smoke, heat, toxic gases and time to detection were made, enabling assessment of time to incapacitation using Fractional Effective Dose methodology. Also described are hazard analyses for fires in which an active suppression was used. These include fires in two-storey maisonettes with and without domestic sprinklers. Results are presented on the relationship between plume oxygen and CO concentrations, and between CO and HCN yields. The effects of interactions between fuel type and load, ventilation and building enclosures are discussed and their implications for choice of design fires appropriate to different fire scenarios. © 2000 Society of Chemical Industry

A two-zone fire growth and smoke movement model for multi-compartment buildings

A fire growth and smoke movement model for a multi-compartment building has been developed at the National Research Council of Canada. This development is primarily intended to help evaluate the risk from fires in buildings. This paper presents the related physical models, numerical methods, and some verification examples. The 2-zone ordinary differential equations (ODEs) are derived for the compartments with fire or smoke. The four independent variables for one compartment are selected as pressure, enthalpy of upper layer, and mass of upper and lower layers. The implemented fire sub-models are introduced, including combustion, fluid flow and heat transfer models. For each compartment without smoke or fire, a non-linear algebraic equation based on mass conservation is used instead of the ODEs. The numerical solution of the governing equations is obtained using a room by room iteration method. In this algorithm, an existing ODE solver, LSODA, has been modified and used to solve the stiff ODEs, and the Steffensen Acceleration Method is used to solve the algebraic equations. Experimental data for single- and two-compartment fire tests are compared to the predictions of the model. The comparison shows favourable results, especially for the upper layer gas temperature, interface height, and vent flow rate.

Toxic product yields and hazard assessment for fully enclosed design fires

Fires in multi-compartment buildings often occur in enclosed spaces or in enclosures opening into other rooms or corridors. Where such fires occur in relatively small enclosures, with limited external venting, the growth of the fire itself remains restricted. If large vents are present opening into large enclosed spaces or to the outside, flashover may occur. In either case these fires are likely to become oxygen vitiated, producing large amounts of smoke and toxic products. Fire-retarded (FR) and non-FR materials behave differently in these situations from the well-ventilated conditions in most standard tests, with smaller differences in toxic product yields. The main hazard to building occupants is the rapid contamination of building spaces by toxic smoke. Visual obscuration and irritancy of smoke impedes escape efficiency, affecting escape behaviour and slowing travel speeds. This may be followed by incapacitation, primarily due to exposure to asphyxiant gases (mainly CO and HCN), and death. A series of full-scale fire tests conducted in enclosed test rigs and buildings is reported, in which detailed measurements of smoke, heat, toxic gases and time to detection were made, enabling assessment of time to incapacitation using Fractional Effective Dose methodology. Also described are hazard analyses for fires in which an active suppression was used. These include fires in two-storey maisonettes with and without domestic sprinklers. Results are presented on the relationship between plume oxygen and CO concentrations, and between CO and HCN yields. The effects of interactions between fuel type and load, ventilation and building enclosures are discussed and their implications for choice of design fires appropriate to different fire scenarios. © 2000 Society of Chemical Industry

A probabilistic model of fire spread with time effects

The paper outlines the principal elements of a probabilistic model that analyses the spread of fire in multi-compartment buildings with respect to time. The analysis uses a graph theoretic network and an event hierarchy to determine the probability of fire spreading to different locations. The probability of fire spreading between compartments is based on a comparison of the probability density functions of the expected fire resistance and the fire severity: failure being the condition that severity exceeds resistance. The model is designed as a comparative tool to compare the performance of different fire safety strategies by calculating a ‘cost index’ for each design, based on the probable extent of fire damage in the building. The analysis gives attention to the compatibility of fire resistance and fire severity, and their conversion in real time parameters.

Oxidation and its influence on the mechanical behaviour of Ni 3Al. (Dissertation) : Dowling Jr, W.E. Diss. Abstr. Int.50, (6), 250 pp, Dec. 1989

A simple mathematical model of stack ventilation flows in multi-compartment buildings is developed with a view to providing an intuitive understanding of the physical processes governing the movement of air and heat through naturally ventilated buildings. Rules of thumb for preliminary design can be ascertained from a qualitative examination of the governing equations of flow, which elucidate the relationships between ‘core’ variables – flow rates, air temperatures, heat inputs and building geometry. The model is applied to an example three-storey office building with an inlet plenum and atrium. An examination of the governing equations of flow is used to predict the behaviour of steady flows and to provide a number of preliminary design suggestions. It is shown that control of ventilation flows must be shared between all ventilation openings within the building in order to minimise the disparity in flow rates between storeys, and ensure adequate fresh air supply rates for all occupants.

Modeling fire spread in buildings

A computer-based technique for analyzing the spread of fire through a multicompartment building is described. The technique is a comparative tool for evaluating alternative fire protection strategies, and quantifies the economic and safety performance characteristics of a building. Some results are shown of its application to a four-story office building.

Outline of a stochastic decision-making model for building fire safety and protection

An outline is given of stochastic state-transition models that have been developed to predict life loss and monetary loss for multi-storey, multi-compartment buildings subject to fire. The stochastic models consider the extent and the effects of smoke and flame spread. Results obtained from the stochastic models can be used to select an appropriate design strategy for the provision of fire safety and protection in buildings, based on the dual attainment of a satisfactory level of predicted life loss and an optimum level of fire-cost expectation. The fire-cost expectation considers costs due to fire losses and the provision of fire-safety and protection measures.