Study The Fire Spread On The Non-loadbearing Timber Structure Combined External Wall

At present,there is not much use of the non-loadbearing timber structure combined external wall,which is still in the stage of popularization and development in China.There are few researches on the performance of the fire,which is usually limited to the study of the fire resistance limit.Usually,the fireproof gypsum board with a certain thickness can meet the requirements of fire resistance.The spread of the flame from the window hole is relatively complicated on the external wall,which is one of the main forms of fire spread in the building.Therefore,this paper mainly studies the vertical spread of the fire on the non-loadbearing timber structure combined external wall.In this paper,the FDS numerical simulation is used to simulate the spread of fire on the external wall of the timber structure.The comparison and analysis of the fire test and the software simulation are carried out to verify the applicability and feasibility of the FDS simulation.Using FDS to simulate the non-loadbearing timber structure combined external wall.The vertical spread of the fire on the composite wall is studied by setting different fireproof eaves,window sill walls,window openings,wind speed and different maintenance structures.At the same time,it also analyzes and compares the spread of the fire at the window opening and door opening on the combined external wall,and summarizes the following conclusions.(1)Compared to the location and thickness,the width of the fireproof eave has the greatest effect on the spread of the fire on combined external wall,and when the width is increased to 500 mm,the effect is already evident.(2)Although the window sill wall can hinder the vertical spread of the fire on the composite wall,but with the increase in the height of the sill wall,the effect is less and less obvious.So in the limited conditions,we can consider window sill wall and fireproof eave together to prevent the vertical spread of fire on the composite wall.(3)The increase in the width of the window opening promotes the spread of the fire on the composite wall,while the increase of the height is opposite.Therefore,when designing the size of the window opening,to avoid high aspect ratio as far as possible.(4)The effect of wind on the vertical spread of the fire in the composite wall is complicated.This paper only considers the vertical wall of the wind,and with the increase of wind speed,the fire increases gradually in the combined exterior wall,butthe influence becomes smaller.(5)Compared with the door openings,the flames and flue gas emitted from the window openings have a greater impact on the combined external wall,and the flames emittes from the door openings have a greater impact on the adjacent buildings.(6)Using the plug gypsum board and wood hanging board to carry out fire simulation study,obtaines that the wooden board accelerates the spread of fire on the combination of the external walls.When the heat release rate of the board material is increased,the temperature of the composite wall increases.Therefore,when setting up the external board,we must use a high fire grade or special fire treatment of the material.