Countering Urban Terrorism in Russia and the United States Proceedings of a Workshop (2006) / Chapter Skim
Currently Skimming:
Special Characteristics of Firefighting in Urban Areas
Special Characteristics of Firefighting in Urban Areas
Pages 60-78
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 60... ...
Firefighting and rescue activity during a terrorist attack are affected by special factors not common in usual firefighting and rescue practice. Explosions partially or completely destroy buildings, which changes the fire development scenario, decreases the fire resistance of structures, and causes hazards for firefighters, rescue workers, and civilians.
|
From page 61... ...
The main purpose of the research was to obtain information necessary for estimating the necessary fire resistance rating for building structures. The impact of a Boeing-767 into the World Trade Center was considered as a model situation.
|
From page 62... ...
It indicates that if the mass of spilled fuel is more than 30 metric tons, the combustion process soon stabilizes and is characterized by a certain average ambient temperature in the enclosure. The duration of the stable period depends on the quantity of fuel.
|
From page 63... ...
Figure 2 shows that combustion became stable in all scenarios, but the average temperatures throughout the enclosure are different. The lowest average temperature is achieved when the opening area is minimal, because in such conditions the combustion process is limited by the oxygen supply (so-called ventilation-controlled fire)
|
From page 64... ...
The mass of the combustible load was assumed to be in the range of 30 to 375 metric tons. The largest value of the combustible load was chosen in accordance with the handbook of Construction Norms and Regulations 21-01-97,2 which establishes the maximum allowable quantity of the combustible load as 50 kilograms/m2 (in 2 Central Scientific Research Institute of Industrial Publications.
|
From page 65... ...
C° T, FIGURE 5 Dynamics of the temperature of the enclosure walls with different quantities of combustible spilled kerosene.
|
From page 66... ...
66 COUNTERING URBAN TERRORISM IN RUSSIA AND THE UNITED STATES 90 t of kerosene quarter opening half opening double opening triple opening C°°CT,T, FIGURE 6 Dynamics of the temperature of the enclosure walls during combustion of 90 metric tons of kerosene with different sizes of opening areas. standard fire C° T, FIGURE 7 Dynamics of average temperature in the enclosure with various quantities of furniture.
|
From page 67... ...
A stable regime is achieved later than with the kerosene fire because the furniture fire spreads more slowly. The construction temperature curves for the furniture fire correlate well with the curves for the kerosene fire (Figures 7 and 8)
|
From page 68... ...
That result correlates with U.S. researchers' estimates that each plane had approximately 30 metric tons of fuel onboard prior to impact.3 Estimate of Fire Endurance of the Damaged Construction Elements Experimental studies were conducted to estimate the effect of mechanical damage on fire resistance time for two types of structural elements: floor panels 3 Hamburger, R., W
|
From page 69... ...
A 200-millimeter transverse chip at the middle of the panel exposing half the diameter of the reinforcement bars decreases fire endurance time by 50 percent. The higher the exposure coefficient for the reinforcement bars, the lower the fire endurance time for the damaged column (for e = 0.03, fire endurance time falls by 6 percent, and for e = 0.14, fire endurance time falls by 21 percent)
|
From page 70... ...
TABLE 1 Theoretical and Experimental Results of Column Fire Resistance Estimates Reinforcement bar Fire resistance exposure coefficient e time , min.
|
From page 71... ...
Therefore, rescue and firefighting operations should be performed quickly in order to save as many trapped victims as possible. Subway Fires Crowds of people, a limited number of evacuation exits, long evacuation paths, and fast-changing hazard dynamics during a fire make subway stations and trains especially dangerous places.
|
From page 72... ...
In recent years, subway trains have become more frequent targets of terrorist attacks. The Tokyo subway was attacked by terrorists using poisonous gas (sarin)
|
From page 73... ...
The most intense temperature dynamic is realized at the end of the train. The experimental studies of hazard factor dynamics during fires in the rail operator's compartment and in undercarriage machinery were carried out on real cars in an experimental tunnel.
|
From page 74... ...
Smoke concentrations reach dangerous levels in 712 minutes, which allows enough time to evacuate people during rush hour. If the emergency ventilation system is not switched on immediately or is ineffective, smoke obscures the evacuation exits within 12 minutes.
|
From page 75... ...
Evacuation time in this first model equals 24.4 minutes. The results of the calculations indicate that the critical values for the accumulation of people in the evacuation routes are not achieved.
|
From page 76... ...
For the 2 m-wide staircase, the estimated evacuation time is approximately 75 percent of that for the narrower staircase, but the accumulation value is still more than critical. Evacuation time may be reduced by using special rescue equipment.
|
From page 77... ...
Reconnaissance showed the area of the fire to be approximately 800 m2, and the nearest fire hydrants were within the terrorists' firing range. The fire department officer in charge decided to employ two hoses supplied by a fire truck water tank, using nearby buildings and structures as cover.
|
From page 78... ...
The hoses were supplied by water carried to the spot in turns by fire truck water tanks. After two more fire vehicles from the special fire brigade of Vladikavkaz and a fire truck from the Ardon fire brigade arrived, a hose line was laid out to supply water from a distant hydrant located in a safe zone.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.