火灾演化、整体火安全和火灾蔓延

本在介绍了自然火灾演化过程及关荷载如何确定后，对建筑整体火安全概念进行了讨论，包括火灾时居民和消防人员的安全性、自然抗火时间、结构火安全设计和财产损失。对结构破坏后的火蔓延计算及标准热荷载的应用也进行了讨论和介绍。

THE EVOLUTION ,GLOBAL SAFETY AND SPREAD OF FIRES

Some concepts of fire safety design of buildings are reviewed in the present paper. The natural fire process and global concept of fire safety design of buildings are discussed. The temperature-time curves of buiding fires are introduced for illustrating the evolution of fire(Fig.1). The expressions for the characteristic values of fire load Q during fires are given in terms of the the relationship between the safety factors and environmental conditions and the reduction of material loss.The global concept of fire safety design is discussed in the second part of the present review.It consists of 4 items,i.e.the safety of occupants and firemen during fire,the required natural fire resistance period (eqn.(3)),fire safety design of structures and the property loss.Some values of the factors involved are given(Tables 1~3).For the fire safety design,the loading density of fire by design q f,d is expressed in terms of safety factors(see eqn.(5) and Tables 4 and 5).In the third part of the present review,the spread of fire and the application of the normalized heat load concept are discussed. The mechanisms of fire spreading are illustrated(Fig.2) and the equations for calcuating the normalized heat load are (eqs.10~12) and Fig.3.It is regarded that the normalized heat load plays an important role in fire safety design, which relates the performance of a building element in the standard test fire to the performance in real-world fires.