Performance-Based Study On Safty Fire Engineering For Ancient Building

China's ancient architecture has a long history and culture,with the ancient building fire bring immeasurable losses of cultural relics and casualties,the state also pay more attention to the protection of ancient buildings.But because of the special nature of ancient buildings,the existing standard is obviously not completely adapt to the design requirements,therefore it is necessary to use more for performance-based fire design.By consulting the relevant literature at home and abroad,there are relatively few projects using fire performance design in ancient buildings,which makes the fire protection design still have some shortcomings.Because of the lack of fire load value in ancient buildings,the design of fire scene is often untraceable.Most ancient buildings can not meet the requirements of theoretical research and current codes,so if the spacing can not be changed,reasonable protection measures should be set up between the ancient buildings.In view of the above difficulties in fire prevention,this paper adopts the methods of field investigation,test verification and numerical simulation.The specific work is as follows:(1)A total of 77 ancient buildings in 12 districts of Beijing were investigated and studied on fire load.The structure form and distribution of internal combustible matter were analyzed and the fixed fire load value and active fire load value of ancient building were obtained.With the help of Matlab software,the distribution of fire load on ancient buildings from the generalized extreme value is obtained,which provides a theoretical basis for setting fire scene more reasonably.(2)In order to effectively reduce the transfer of thermal radiation between ancient buildings and prevent the spread of large areas of fire due to insufficient fire spacing,a mobile high pressure water mist fire prevention separation test was carried out.By changing the fire source position and working pressure,analysis of the ratio of thermal radiation to temperature at different working conditions,and the optimum arrangement scheme of the high pressure water mist is determined.(3)The safety criteria for evacuation of ancient building personnel were determined.The feasibility of fire simulation software was verified by comparing the results of FDS fire simulation with water mist test.Using FDS fire simulation software,according to the actual fire load distribution,The emulation of a single ancient building in the investigation is carried out to analyze the laws of smoke spread,temperature field,visibility,toxic gas volume fraction,heat radiation transfer between the vertical and lateral facades.By comparing the simulation results with the criteria of evacuation safety,the time of fire hazard is determined.(4)Based on the fire spread of ancient buildings under the condition of high pressure water mist opening and closing,the related parameters of individual ancient building and the high pressure water mist device are applied to the simulation.The results show that the fire spread can be effectively controlled under the protection of water mist.In this paper,a preliminary performance-based design scheme for ancient buildings is developed,which can be used as a reference for the performance-based design of similar ancient buildings.