Study On Smoke Temperature Rise Of Large Space Buildings Based On Fire Randomness

As an important kind of architectural form,large space buildings are widely used in architectural design,such as large-scale station,terminal,atrium,exhibition hall,and auditorium.Large space buildings have large construction scale,high space,special structure and high fire risk,which make new demands for the prevention and rescue of fire.Large space building smoke temperature rise will have a great impact on building structure,evacuation,fire fighting and rescue.The process of fire development is the process of coexistence of determinism and randomness,but its randomness is not chaotic and irregular.The randomness factor of fire development process will follow certain statistical rules.Therefore,it is of great practical significance to study the smoke temperature rise of the large space buildings based on fire randomness.In this paper,the variance analysis method was used to study the effect of various factors on the temperature rise of large space fire smoke.The results showed that the most significant factor affecting the temperature of fire smoke is the fire source power.In the random analysis,the randomness of the parameters that affect the fire power should be analyzed.Based on the theory of fire dynamics and the experiment of large space fire,the temperature rise characteristics of large space fire smoke were studied.The experimental results showed that the temperature fluctuation in the flame area was larger than that in the plume area,and the temperature gradually decreased with the increase of the plume height.In the ceiling jet area,the smoke temperature tends to decrease with the spatial point away from the fire centerline,and has obvious non-uniform distribution characteristics.At the same time,according to the experimental results,the feasibility of the parametric temperature rise model in predicting the temperature rise of fire smoke in large space is verified.In the case of random analysis of large space temperature rise,the parameters influencing the large space temperature rise model are divided into deterministic parameters and random parameters.The probability density function of random parameters were studied.It is concluded by field work that the fire load density of station type large space buildings obeys the normal distribution.Through the data inspection and analysis,it is concluded that the flammability coefficient of the material obeys the uniform distribution,the fire area and the fire growth coefficient obey the logarithmic normal distribution.After the probability density function of each random parameter is determined,the average values,standard deviation values,PDF curve and CDF curve of the maximum heat release rate,the equivalent diameter of the fire source and the maximum temperature rise of the fire center line were obtained by using the Latin hypercube sampling method.The results showed that the maximum temperature rise of the fire center line obeys logarithmic normal distribution.The logarithmic mean value is 5.8697 and logarithmic standard deviation value is 0.31396.The probability density function of the maximum temperature rise of the fire center line was obtained.The probability distribution of the maximum temperature rise of smoke at different distances from the fire center line were studied.The maximum temperature rise at each distance obeys the lognormal distribution and the maximum temperature rise probability density function at each distance was obtained.The application of smoke temperature rise probability distribution in large space buildings was described through the case study.According to the critical temperature criterion,the failure probability of large space steel structure is analyzed,and the failure probability of the steel structure was calculated in the case study.In order to facilitate the calculation and analysis of smoke temperature rise probability distribution of buildings with different area,height and fire load,the programme of "Smoke Temperature Rise of Large Space Buildings Based on Fire Randomness and Structural Failure Analysis" was developed.