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

本文的主要工作包括：1）建立火灾安全性能化设计的技术基础; 2）改进双层区域模型的预测方法; 3）设计火源的表征。对于第1）项，分析了现行疏散设计中包含的目标安全水平，发现安全指数（所谓的β系数）在1和3之间。对结构抗火设计也进行了类似的分析。此外，还对高层酒店和露天停车场进行了案例研究。对于第2）项，对以下两个物理过程进行了实验和理论研究。通过模型试验分析了机械排烟系统的卷气问题，发现以排烟口短边长为特征直径的弗劳德数可以描述防止卷气的临界层厚。通过真实实验分析了楼梯间内自然烟气的蔓延规律，发现楼梯间内的温度分布近似为向上指数衰减。这两个模型被归纳为易于实现的两层区域模型烟气蔓延计算机程序。对于第3项，讨论了合理设计放热率的可能性。为了建立一种测量聚氨酯床垫燃烧特性实验数据的方法，利用HRR实验分析了试样尺寸的影响。类似的方法正在开发用于各种可燃物。最后，开发了一个预测多种可燃物火灾蔓延速度的计算机程序。

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.