On Smoke Control In Staircase Of Public Buildings Under Natural Ventilation Mode

Building fires have the characteristics of rapid spread,difficult evacuation,difficult rescue and great economic losses.Modern buildings,whether civil buildings,public buildings,industrial buildings or agricultural buildings,most of the evacuation corridors are stairs.Stairs are the main choice for people to escape.In the process of escaping,because of the spread of fire smoke,poor visibility,high temperature,increased concentration of toxic gases and so on,it becomes difficult for stairs to escape.Therefore,it is of great value to reduce fire hazards and casualties by studying stairwell smoke prevention.This research combines the project sponsored by Liaoning Natural Science Foundation(Project No.20180550336)to study the smoke control of stairwell in public buildings under natural ventilation mode.Natural smoke exhaust is a simple and reliable smoke exhaust mode without consuming power.In this paper,a 12-storey office building with a total height of 48m and a height of 4m is numerically simulated.Firstly,the model is established by Revit(BIM),and then imported into FDS for simulation.The smoke control effect of stairwell under natural ventilation mode is simulated through two cases.In the first case,by changing the area of the natural smoke exhaust window in the fire room,the stairwell will not smoke.In the second case,let the smoke enter the stairwell by changing the layout of the stairwell windows to minimize the impact of smoke on the evacuation of stairwell personnel.Specific research contents and conclusions are as follows:(1)When the fire source is on the first floor,it can be simulated by FDS that 2%of the room area set in accordance with the specifications is opened to set windows,which does not meet the requirements of smoke prevention in stairwell.The effective area of the first floor fire source room is not less than 2.5%of the building area of the room.The smoke will not enter the stairwell,so the smoke control effect will be better.Simulated fire source in the middle and upper,according to the standard set room area of 2%to open the window is in line with the stairwell smoke control requirements,and there is a certain degree of redundancy.It is suggested that the code be revised as follows:in places with net height less than 6m under natural smoke exhaust mode,natural smoke exhaust windows with effective area not less than 3%of the building area of the room should be installed.(2)The stairwell window layout has the best smoke control effect on the premise that it meets the requirement of 2 m2 in each 5 floors.(3)The main way of exhaust gas entering the front chamber is different according to the location of the fire source.When the fire source is on the first floor,the smoke entering the front room is mainly discharged from the stairwell window.When the fire source is not on the first floor,the smoke entering the front chamber is mainly discharged from the front chamber window.(4)By comparing the smoke exhaust volume of the window and the front room of the fire room,the smoke is mainly discharged from the outside window of the fire room after the fire.