November 27, 1998

Takenaka Corporation

Takenaka has developed and utilized a "fire propagation simulation system" that can analyze and predict how a fire burns in large spaces such as concert halls and auditoriums that have interior walls made of solid wood.
In order to be able to use wood in interior walls of concert halls, etc., it is first necessary to conduct exhaustive burning experiments to determine the fire resistance and safety of the material, which then must be approved by the Construction Minister. The fire propagation simulation system that we have just developed can analyze burning characteristics on a computer. It can precisely simulate how a fire might burn wooden walls in a large indoor space, and determine the location and time needed for fire stoppage (that is, the time needed for the charred surface of the wood to act as a fire retardant). This helps to greatly reduce the outlays of time and money needed for the experiments.
In addition, the fire propagation simulation system combines two of our other simulation systems, one for smoke ¹⁾ and the other for evacuation ²⁾, to establish a method for evaluating the safety of evacuating a burning auditorium, etc., that has interior walls containing wood. We have used this method in our projects with new and existing auditoriums, etc., to help us make the most use of the sensuousness and acoustic effects of wood in large indoor spaces.

1) This smoke dispersion simulation system analyzes the flow of smoke during a fire.
2) This evacuation simulation system analyzes the evacuation conditions of the occupants of a burning auditorium, etc.

• Background behind the development of the "fire propagation simulation system
  
  When used in the walls of large indoor spaces, wood helps to convey a sense of warmth. It also improves the natural acoustics of concert halls. Many such halls exist overseas, and demand is rising for them in Japan. However, in most cases the Japanese Building Standards Act mandates that large indoor spaces such as auditoriums and concert halls have interior walls that are made of nonflammable materials. Presently, most of the walls of such facilities in Japan that look wooden are actually made of gypsum boards that are covered by very thin wooden veneers.
  To use flammable materials like wood as interior wall materials for concert halls, etc., in Japan, it is first necessary to conduct a thorough investigation to determine whether, in case of fire, occupants can be evacuated safely and the fire will not spread. Then, approval must be received from the Minister of Construction. Given this situation, exhaustive burning experiments that use real-life models are generally conducted to assess fire resistance and safety, but these experiments require large outlays of time and money.
  
  

• What is the "fire propagation simulation system"?
  
  The fire propagation simulation system is a means for analyzing how a fire might spread in large halls, etc. that have wooden walls.
  First, various data, such as the type, thickness, specific gravity and burnability of the wood, and the size, wall height, seating arrangement, etc. of the hall are entered into the computer and analyzed. Then the system suggests a plan in which the wooden walls would be arranged to ensure the safety of an evacuation, and the fire would stop quickly and would not spread. Since a large computer is used, the system can perform a variety of investigative functions more quickly and economically than model-based burning experiments.
  Recently, much has been learned about how wood burns. For its part, Takenaka has amassed a large amount of data from its many actual-scale model burning experiments. The knowledge we have acquired from these experiments has been used to make the present fire propagation simulation system ready for practical use.

• How is the safety of evacuation assessed?
  
  The method we have devised for assessing evacuation safety consists of three systems: (1) the fire propagation simulation system, which analyzes how wooden walls burn after they catch fire, (2) the smoke dispersion simulation system, which analyzes the flow of smoke after a fire starts, and (3) the evacuation simulation system, which analyzes various facets of evacuating the occupants of a large hall.
  First, the fire propagation simulation system (1) analyzes the condition of the fire propagation and the location and time of fire stoppage, based on the proposed design, and ascertains that any potential fire could not spread so far as to pose a danger. Next, based on the amount of heat released from seats and wooden walls, etc., the smoke dispersion simulation system (2) analyzes how smoke would spread in the hall. Finally, the evacuation simulation system (3) is used to calculate the time needed for the occupants of an auditorium to evacuate from the start of the fire.
  The results from these simulations can confirm the safety of a design of a hall, such as the ability of occupants to evacuate in case of fire, and the containability of the fire. This system will now be used at Takenaka to design large indoor spaces which take full advantages of the unique qualities of wood.