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With the increasingly rampant terrorist attacks, the research on how to resist the effects of explosions in civil and industrial architectures becomes an urgent mission. For China, the structures like dams, nuclear power plants, airports, large stadiums, super high-rise buildings, are easily become the top targets of bomb attacks. These kinds of structures are bearing thousands of people’safety and property, and the destruction of them can produce much more damage than other explosions. The flat roof structures as a commonly seen space structure, is widely used in some major architectures like airport and repository. It is a necessary and urgent matter to study how to resist the effects of explosions in the large-span flat roof structures.In this research, we try to find out the distribution law of the overpressure on the large-span flat roof structures by using explicit formulation finite element analysis software--LS-DYNA. After determining the parameters and the settings of the computation with LS-DYNA, we build air explosion model, which is tested to ensure the parameters and the settings of the computation. The size of the air element is also tested.By using the ensured method of modeling the large-span flat roof structures, 3 models of the object of study --30m ? 30m ? 15m large-span flat roof structures, which are 1/4 model, rectangle 1/2 model, diagonal 1/2 model, are built. Then this paper studies the law of the spread of the shock wave in the large-span flat roof structures, and the law of the distribution of the overpressure field on the roof of the structures, and the influence on the overpressure field by the change of the parameters of TNT. A database of the overpressure field is built to help the later researchers.After the study of the law of the distribution of the overpressure field, this paper comes up with three methods,namely subarea simulation method ,shape function interpolation method, fitting formula method, which can be properly applied to the rebuilding of the overpressure field of the roof of the large-span flat roof structures. And the author discusses the usage and error of the three methods respectively.
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