scholarly journals Mine Fire Behavior under Different Ventilation Conditions: Real-Scale Tests and CFD Modeling

2020 ◽  
Vol 10 (10) ◽  
pp. 3380 ◽  
Author(s):  
Florencio Fernández-Alaiz ◽  
Ana Maria Castañón ◽  
Fernando Gómez-Fernández ◽  
Marc Bascompta
Keyword(s):  
Fire Behavior ◽  
Load Ratio ◽  
Cfd Modeling ◽  
Fuel Load ◽  
Fire Dynamics ◽  
Mine Fire ◽  
Before And After ◽  
Fire Scenarios ◽  
Scale Spaces ◽  
Real Scale

Fires in underground spaces are especially relevant due to their potential mortality. However, there is not much research in real-scale spaces done so far. In this study, several fire scenarios were analyzed in an underground drift, taking into account the main environmental variables: airflow, temperature, oxygen, and pollutants. The behavior before and after the fire load was determined, as well as the evolution of the fire over time throughout the drift and its cross-section, finding important trends of the fire based on the airflow–fuel load ratio. Furthermore, the five most representative scenarios were modeled using the fire dynamics simulator (FDS). Results obtained in the simulations, with the adjusted parameters, display a good correlation between simulated and experimental values, being able to extrapolate these values to know the performance of potential fires in other underground spaces or mines. The outcomes could also be a very useful tool to study the effectiveness of possible emergency measures or the potential impact of a fire in this type of environments.

Study of the Fire Service Training Environment: Safety and Fidelity in Concrete Live Fire Training Buildings

2018 ◽  
Author(s):  
Jack Regan ◽  
◽  
Robin Zevotek
Keyword(s):  
Oriented Strand Board ◽  
Fire Behavior ◽  
Fire Service ◽  
Fuel Load ◽  
Living Room ◽  
Synthetic Fuels ◽  
Fire Dynamics ◽  
Training Environment ◽  
Service Training ◽  
Series Of Experiments

The goal of fire service training is to prepare students for the conditions and challenges that they face on the fireground. Among the challenges that firefighters routinely face on the fireground are ventilation-controlled fires. The hazard of these fires has been highlighted by several line-of-duty deaths and injuries in which a failure to understand the fire dynamics produced by these fires has been a contributing factor. The synthetic fuels that commonly fill contemporary homes tend to result in ventilation-controlled conditions. While synthetic fuels are common on the residential fireground, the fuels that firefighters use for fire training are more often representative of natural, wood-based fuels. In order to better understand the fire dynamics of these training fires, a series of experiments was conducted in a concrete live fire training building in an effort to evaluate the fidelity and safety of two training fuels, pallets and OSB, and compare the fire dynamics created by these fuels to those created by a fuel load representative of a living room set with furniture items with a synthetic components. Additionally, the effects of the concrete live fire training building on the fire dynamics were examined. The two training fuel loads were composed of wooden pallets and straw, and pallets, straw, and oriented strand board (OSB). The results indicated that the high leakage area of the concrete live fire training building relative to the fuel load prevented the training fuel packages from becoming ventilation-controlled and prevented the furniture package from entering a state of oxygen-depleted decay. The furniture experiments progressed to flashover once ventilation was provided. Under the conditions tested, the wood based fuels, combined with the construction features of this concrete live fire training building, limited the ability to teach ventilation-controlled fire behavior and the associated firefighting techniques. Additionally, it was shown that the potential for thermal injury to firefighters participating in a training evolution existed well below thresholds where firefighter PPE would be damaged.

scholarly journals Performance-Based Analysis of Single-Layer Cylindrical Steel Reticulated Shells in Fire

2020 ◽  
Vol 10 (9) ◽  
pp. 3099
Author(s):  
Zhiwei Yu ◽  
Chen Lu ◽  
Yiqin Zhong
Keyword(s):  
Fire Resistance ◽  
Rapid Development ◽  
Single Layer ◽  
Steel Structures ◽  
Temperature Fields ◽  
Fe Model ◽  
Fire Dynamics ◽  
Interior Space ◽  
Coating Materials ◽  
Fire Scenarios

With the rapid development of architectural technology, long-span structures have been widely used due to their vast interior space and beautiful architectural composition. Due to the characteristics and high costs of coating materials on large steel structures, fire resistance designs for these kinds of structures have become more and more important. This paper presents comprehensive case analyses of the fire performance of single-layer cylindrical reticulated shells. Nonuniform fire temperature fields of single-layer cylindrical reticulated shells in different fire scenarios were generated using a Fire Dynamics Simulator (FDS). The influences of different parameters on the air temperature field during a fire in a reticulated shell structure were analyzed. A Finite Element (FE) model was developed using the FE software ABAQUS to model the structural behavior of single-layer cylindrical reticulated shells in different fire scenarios. The effects of various parameters on the responses of single-layer cylindrical reticulated shells during a fire were investigated. Using the results from the performance-based analysis in this research, we propose some recommendations for fire resistance designs for single-layer cylindrical reticulated shells.

scholarly journals Synthesis of Novel Polymeric Acrylate-Based Flame Retardants Containing Two Phosphorus Groups in Different Chemical Environments and Their Influence on the Flammability of Poly (Lactic Acid)

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 778 ◽  
Author(s):  
Jacob Sag ◽  
Philipp Kukla ◽  
Daniela Goedderz ◽  
Hendrik Roch ◽  
Stephan Kabasci ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Mode Of Action ◽  
Flame Retardants ◽  
Fire Behavior ◽  
Heat Fluxes ◽  
Poly Lactic Acid ◽  
Cone Calorimetry ◽  
Scanning Calorimetry ◽  
Fire Scenarios ◽  
Physical Phenomena

Novel polymeric acrylate-based flame retardants (FR 1–4) containing two phosphorus groups in different chemical environments were synthesized in three steps and characterized via nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mass spectrometry (MS). Polylactic acid (PLA) formulations with the synthesized compounds were investigated to evaluate the efficiency of these flame retardants and their mode of action by using TGA, UL94, and cone calorimetry. In order to compare the results a flame retardant polyester containing only one phosphorus group (ItaP) was also investigated in PLA regarding its flame inhibiting effect. Since the fire behavior depends not only on the mode of action of the flame retardants but also strongly on physical phenomena like melt dripping, the flame retardants were also incorporated into PLA with higher viscosity. In the UL94 vertical burning test setup, 10% of the novel flame retardants (FR 1–4) is sufficient to reach a V-0 rating in both PLA types, while a loading of 15% of ItaP is not enough to reach the same classification. Despite their different structure, TGA and cone calorimetry results confirmed a gas phase mechanism mainly responsible for the highly efficient flame retardancy for all compounds. Finally, cone calorimetry tests of the flame retardant PLA with two heat fluxes showed different flame inhibiting efficiencies for different fire scenarios.

scholarly journals No evidence of increased fire risk due to agricultural land abandonment in Sardinia (Italy)

2012 ◽  
Vol 12 (5) ◽  
pp. 1333-1336 ◽  
Author(s):  
C. Ricotta ◽  
D. Guglietta ◽  
A. Migliozzi
Keyword(s):  
Rural Areas ◽  
Agricultural Land ◽  
Plant Biomass ◽  
Fire Hazard ◽  
Fire Behavior ◽  
Land Abandonment ◽  
Fuel Load ◽  
Short Paper ◽  
Ignition Probability ◽  
Fire Ignition

Abstract. Different land cover types are related to different levels of fire hazard through their vegetation structure and fuel load composition. Therefore, understanding the relationships between landscape changes and fire behavior is of crucial importance for developing adequate fire fighting and fire prevention strategies for a changing world. In the last decades the abandonment of agricultural lands and pastoral activities has been the major driver of landscape transformations in Mediterranean Europe. As agricultural land abandonment typically promotes an increase in plant biomass (fuel load), a number of authors argue that vegetation succession in abandoned fields and pastures is expected to increase fire hazard. In this short paper, based on 28 493 fires in Sardinia (Italy) in the period 2001–2010, we show that there is no evidence of increased probability of fire ignition in abandoned rural areas. To the contrary, in Sardinia the decreased human impact associated with agricultural land abandonment leads to a statistically significant decrease of fire ignition probability.

scholarly journals Estimating Fuel Loads and Structural Characteristics of Shrub Communities by Using Terrestrial Laser Scanning

2020 ◽  
Vol 12 (22) ◽  
pp. 3704
Author(s):  
Cecilia Alonso-Rego ◽  
Stéfano Arellano-Pérez ◽  
Carlos Cabo ◽  
Celestino Ordoñez ◽  
Juan Gabriel Álvarez-González ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Goodness Of Fit ◽  
Fire Hazard ◽  
Structural Characteristics ◽  
Fire Behavior ◽  
Terrestrial Laser Scanning ◽  
Fuel Load ◽  
Fuel Loads ◽  
Litter Depth ◽  
Species Specific

Forest fuel loads and structural characteristics strongly affect fire behavior, regulating the rate of spread, fireline intensity, and flame length. Accurate fuel characterization, including disaggregation of the fuel load by size classes, is therefore essential to obtain reliable predictions from fire behavior simulators and to support decision-making in fuel management and fire hazard prediction. A total of 55 sample plots of four of the main non-tree covered shrub communities in NW Spain were non-destructively sampled to estimate litter depth and shrub cover and height for species. Fuel loads were estimated from species-specific equations. Moreover, a single terrestrial laser scanning (TLS) scan was collected in each sample plot and features related to the vertical and horizontal distribution of the cloud points were calculated. Two alternative approaches for estimating size-disaggregated fuel loads and live/dead fractions from TLS data were compared: (i) a two-steps indirect estimation approach (IE) based on fitting three equations to estimate shrub height and cover and litter depth from TLS data and then use those estimates as inputs of the existing species-specific fuel load equations by size fractions based on these three variables; and (ii) a direct estimation approach (DE), consisting of fitting seven equations, one for each fuel fraction, to relate the fuel load estimates to TLS data. Overall, the direct approach produced more balanced goodness-of-fit statistics for the seven fractions considered jointly, suggesting that it performed better than the indirect approach, with equations explaining more than 80% of the observed variability for all species and fractions, except the litter loads.

Numerical Prediction of the Fire Spread in Vegetative Fuels Using NISTWFDS Model

2015 ◽  
Vol 20 ◽  
pp. 177-192 ◽  
Author(s):  
Hadj Miloua
Keyword(s):  
Forest Fires ◽  
Wildland Fire ◽  
Radiation Heat Transfer ◽  
Fire Behavior ◽  
Reaction Diffusion ◽  
Fire Spread ◽  
Three Dimensions ◽  
Forest Stands ◽  
Fire Dynamics ◽  
Wind Climate

Current study focuses to the application of an advanced physics-based (reaction–diffusion) fire behavior model to the fires spreading through surface vegetation such as grasslands and elevated vegetation such as trees present in forest stands. This model in three dimensions, called Wildland Fire Dynamics Simulator WFDS, is an extension, to vegetative fuels, of the structural FDS developed at NIST. For simplicity, the vegetation was assumed to be uniformly distributed in a tree crown represented by a well defined geometric shape. This work on will focus on predictions of thermal function such as the radiation heat transfer and and thermal function for diverse cases of spatial distribution of vegetation in forest stands. The influence of wind, climate characteristics and terrain topography will also be used to extend and validate the model. The results obtained provide a basis to carry out a risk analysis for fire spread in the studied vegetative fuels in the Mediterranean forest fires.

Dentin Erosion Simulation by Cantilever Beam Fatigue and pH Change

2005 ◽  
Vol 84 (4) ◽  
pp. 371-375 ◽  
Author(s):  
M. Staninec ◽  
R.K. Nalla ◽  
J.F. Hilton ◽  
R.O. Ritchie ◽  
L.G. Watanabe ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
High Stress ◽  
Load Ratio ◽  
Maximum Load ◽  
Cyclic Fatigue ◽  
Ph Change ◽  
Material Loss ◽  
Dimensional Changes ◽  
Before And After ◽  
Human Dentin

Exposed root surfaces frequently exhibit non-carious notches representing material loss by abrasion, erosion, and/or abfraction. Although a contribution from mechanical stress is often mentioned, no definitive proof exists of a cause-effect relationship. To address this, we examined dimensional changes in dentin subjected to cyclic fatigue in two different pH environments. Human dentin cantilever-beams were fatigued under load control in pH = 6 (n = 13) or pH = 7 (n = 13) buffer, with a load ratio ( R = minimum load/maximum load) of 0.1 and frequency of 2 Hz, and stresses between 5.5 and 55 MPa. Material loss was measured at high- and low-stress locations before and after cycling. Of the 23 beams, 7 withstood 1,000,000 cycles; others cracked earlier. Mean material loss in high-stress areas was greater than in low-stress areas, and losses were greater at pH = 6 than at pH = 7, suggesting that mechanical stress and lower pH both accelerate erosion of dentin surfaces.

Numerical analysis of lateral displacement of beam-column joints in concrete frame structures subjected to fire

2017 ◽  
Vol 21 (10) ◽  
pp. 1495-1509 ◽  
Author(s):  
Bo Wu ◽  
Jinsong Liu ◽  
Xiaomei Chen
Keyword(s):  
Reinforced Concrete ◽  
Numerical Analysis ◽  
Lateral Displacement ◽  
Load Ratio ◽  
Time Dependent ◽  
Concrete Frames ◽  
Reinforced Concrete Column ◽  
Concrete Frame ◽  
Fire Scenarios ◽  
Column Joint

In this article, numerical analysis has been conducted for multi-story reinforced concrete frames under different fire scenarios to investigate the time-dependent lateral displacement of beam-column joint, which is almost the same as the lateral displacement at column end. Based on the numerical results, an empirical model has been proposed to approximately determine the time-dependent lateral displacement of the beam-column joint, and the calculated results using this model are compared with the numerical and test results provided by other researchers. Finally, the fire performance of axially-and-rotationally restrained reinforced concrete columns with time-dependent sidesway is numerically analyzed and compared with that without sidesway. It is found that (1) when the target floor is on fire, the influence of its non-adjacent floors’ exposure to fire on the lateral displacement of the joints at the target floor can be neglected, and the biggest error induced by this neglect is less than 10%; but the exposure of its adjacent floor(s) to fire leads to larger lateral displacement of these joints; and (2) fire endurance of the restrained reinforced concrete column with high nominal axial load ratio (e.g. 0.6) decreases significantly with the increasing of the column’s sidesway.

Sign in / Sign up

Export Citation Format

Share Document