Research On Fire Response And Performance-based Fire Resistant Design Of Pre-stressed Suspended Lattice Shells

It is known that strength of steel material reduces significantly under high temperature in fire. For pre-stressed structure system, the pre-stress relaxation of steel cables with high strength in high temperature is likely to cause structural collapse. The pre-stressed structures with large space has many forms, and reactions of their mechanical property in fire are different, so it is necessary to carry out research on behavior of all forms of pre-stressed spatial structures subjected to fire load. Based on summarizing basic theory and results on existing fire resistance research of the large space and pre-stressed structures, the features and basic usage of the fire dynamics simulation software FDS and the structural finite element analysis software Marc are introduced, and by comparison with the experimental data given in references, the rationality of FDS usage and reliability of the method used for analysis of temperature field of large space structure are mainly discussed.Secondly, combined with the experiential formula of large space fire presented in fire protection code the finite element analysis software Marc are used to analyze a new suspended lattice cylindrical shell in many situations, including various fire source location, various heights and various rise-span ratio. Through discussion of the force mechanism, fire behavior and destruction forms at extreme temperature, it is concluded that, (1)For the same fire power, the vertical positive displacement for central fire is maximum, while fire source is below the second ring cable, the failure cables is most;(2)As the temperature rises, the time of pre-stressed cable failure is shorter;(3)The limit temperatures of the structures with different rise-span ratio are almost same, but the deformation is more acceptable when the rise-span ratio is 1 / 10.Finally, the fire temperature field simulation software FDS and finite element software Marc are used to analyze a gymnasium structure for performance-based fire protection design, and the fire safety evaluation is conducted. On the one hand, the structure's fire resistance characteristics according to a more realistic fire was analyzed, on the other hand, the feasibility and the implementation steps of the performance-based fire resistance design applied on actual large space structures for fire safety design are further definite. It is shown that the temperature rise formula of large space is good for use in general, but there are some differences from actual situation because of the limitation of parameters in formula, such as building area, space height and the actual roof forms of structure, which will affect the maximum temperature and the distribution of temperature in fire.