Development of Engineering Design Methods for Fire Safety by using Fire Behavior Prediction Models

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This work is concerned with ; 1) development of technical basis for performance-based design for fire safety, 2) Improvement of prediction made by two-layers zone model, 3) characterization of design fire-source. As to item 1), target safety level included in current evacuation design is analyzed to find that the safety index (so-called beta factor) is in the range of 1 and 3. Similar analysis was carried-out also for structural fire resistance design. In addition, case studies were carried out for high-rise hotel and open car park. As to item 2), experimental and theoretical studies were carried out for the following two physical processes. Air entrainment into mechanical venting system was analyzed by model scale experiments to find that the critical layer thickness to prevent air entrainment could be described by Froude number using short edge length of smoke vent as characteristic diameter. Natural smoke spread behavior in stair shaft was analyzed by real-scale experiments to find that temperature profile is approximated by exponential decay toward upward. These two models were summarized to be easily implemented into two-layer zone model smoke spread computer code. As to item 3), the possibility of rationalize design heat release rate is discussed. To develop a method to scale experimental data of combustion behavior, the effect of specimen size was analyzed using HRR experiments conducted for polyure thane mattress. Similar methods are being developed for a variety of combustibles. Finally, a computer code has been developed to predict fire spread velocity over multiple combustibles.