Research On Performance-based Fire Protection For Large Scale Public Buildings

With the improvement of national economy and the rapid development of science and technology, to keep the pace, the large-scale public buildings such as train stations, airports and exhibition halls have been constructing in recent years. However, the public buildings have complicated structures, versatile functions, and a large quantity of combustible matter. If they catch fire, the consequence will be disastrous. Therefore, fire protection for large-scale public buildings becomes one significant part of fire research work. As it is mentioned that the public buildings have complicated structures and occupy a large space in both level surface and height, their fire safety design in the respect of fire compartmentation, safety evacuation, smoke control, construction protection and active fire-protection installations cannot be made according to the national fire protection design code. This not only challenges the traditional"prescriptive"fire-protection design codes, but also becomes one of the problems for building fire protection to be solved.This paper first analyzed the severe fire situations in China, presented a prediction of fire trends for the near future, and analysed the underlying reasons caused by fire trends. Based on the dissipative structure theory, the thermodynamic implications of fire and its hazard on the sustainable development of national economy were analyzed thoroughly, pointing out that the new technology of fire protection and control is very important for improving the building safety and the social capability to combat fire disaster. For this reason, performance-based fire safety design was considered as an effective solution to the fire safety design for large-scale public buildings. Above all, this research laid emphasis on fire growth model, fire propagation behaviors of combustibles and flashover characteristics in typical parts within the large-scale public buildings. They are as follows:In the first place, from a theoretical approach, fire models including theoretical/empirical models of heat release rates and flame propagation models for large-scale public buildings were analyzed and derived; predictive models for critical heat release rates during flashover was compared; the smoke plume control models was formulated. From an experimental approach, full-scale fire tests were carried out, using different arrangements of fuels (i.e. rack arrangement and pile arrangement), with standard modules representing packaged commodities. Through the analysis of experiment results, combustion characteristics during different fire development periods was elucidated; the effects of temperature, radiation heat flux and fire load and etc. on fire growth and propagation behaviors were analyzed. Besides, the effects of fire load, smoke exhaust and air makeup on the occurrence of flashover were also investigated through systematic experiments, and some valuable conclusions were obtained, which would be useful for engineering practices.On the basis of above research work, the conception of"cabin"and"fuel island"was introduced to represent the particular structure characteristics and fire hazards of large-scale public buildings. The mathematical model describing fire growth and smoke movement in open spaces of large-scale shopping malls was established, and corresponded computer software was developed. The software could be used to simulate fire development process and predict smoke movement characteristics in large-space buildings. To verify the simulation results, large-scale space fire test installations were set up and verification experiments were carried out. The result indicated that the mathematical model was appropriate and credible, and the predicted results agreed well with the experiment results to a large extent, with an error below 20%.According to the theoretical analysis and experimental results, a set of design strategy for the performance-based fire safety design of large-scale public buildings was proposed. Important sections during the whole design process including the determination of safety goals, quantification of performance criterion, setup of fire scenario, design of smoke control system, selection of human evacuation strategy, fire compartmentation and fire-resistance design of building structures were treated comprehensively, which could provide a practical solution to the performance-based fire safety design of large-scale public buildings.The final part of this paper conducted a case study about the performance-based fire safety design for a train station, using the proposed design strategy above. Furthermore, uncertainty analysis and security assessment for the train station was carried out. The case study illustrated that, as to the fire protection design for large-scale public buildings, performance-based fire safety design can provide appropriate solutions to some special problems which current fire codes or standards do not cover, and thus an optimal balance between safety performance and economic investment was achieved.