Study On Fire Resistance Of Single-layer Cylindrical Reticulated Shell

In China,fire is the third largest disaster affecting the safety of life and property after the drought and flood.Fire accidents are not only harmful,but also have a great negative impact on society.With the rapid development of science and technology in China,large span space structures have developed rapidly.Large span space structures,such as gymnasium,exhibition center,is a city landmark,which brought together a large number of people and capital.Personnel and economic losses caused by fire would be huge.Because of the characteristics and high cost of coating material of the large space steel structure,the fire resistance design of this kind of structure becomes more and more important.In 2006,the "Technical code for fire safety of steel structures in buildings" has been published.However,it still lacks of the research on fire performance and calculation of large space steel space structures.Therefore,based on the previous research,the paper has studied the failure characteristic and the fire resistance design method of large-span steel reticulated shells under fire.The main contents are as follows:(1)Research on fire resistance analysis method of single-layer cylindrical reticulated shell structureIn this paper,the single-layer cylindrical reticulated shell structure commonly used in engineering is taken as the research object.First of all,the physical and mechanical properties of the steel structure under high temperature conditions are analyzed.Secondly,based on the basic principles of heat transfer under fire,a practical calculation method for the temperature rise of steel components under fire is determined.Finally,the calculation method of air temperature field under fire of asingle-layer cylindrical reticulated shell structure is discussed.An analytical method suitable for the air temperature field in a large space steel structure fire is determined by comparative analysis(2)Temperature field simulation of a single-layer cylindrical reticulated shell under fireFirstly,the non-premixed combustion fire model is used to describe the combustion process of combustibles,and the turbulence model,radiation model and combustion model for non-premixed combustion model are determined.Based on the international general fire simulation software FDS,numerical simulations were conducted to obtain the distribution of air temperature field(rising temperature curve)for single-layer cylindrical reticulated shells under fire conditions.Secondly,compared with the temperature rising curves of the large space building under the fire in the experiment,the validity and accuracy of the simulated air temperature field distribution are obtained.Finally,the influence of different parameters on the air temperature field under the fire of the reticulated shell structure was analyzed,so that the influence rules of different parameters on the air temperature field of a single-layer cylindrical reticulated shell in the fire was obtained,such as fire source position,heat release rate,and rise to span ratio,etc.(3)Study on mechanical behavior and failure characteristics of single-layer cylindrical reticulated shell structures subjected to fireFirst of all,the mechanical properties of single-layer cylindrical reticulated shells under fire are studied systematically.The transient response analysis method for single-layer cylindrical reticulated shells under fire is established to investigate the displacement response,the law of internal force changes of single-layer cylindrical reticulated shells under fire conditions and the influence of different parameters(structural parameters,fire parameters,etc.)on the overall fire response of a single-layer cylindrical reticulated shell structure.Secondly,based on the existing research,the discriminant criterion of failure in fire of reticulated shell structure is proposed,and the failure characteristics of single-layer cylindrical reticulated shell structure under the fire are obtained.Finally,the influence of various parameters(fire source location,heat release rate,protective layer thickness,and rise span ratio,etc.)on the characteristic response of single-layer cylindrical reticulated shells under fire is investigated.