| Large-space steel structures have been widely used in China by its virtue of magnificent shape and enormous interious space etc. However, the steel material is weak in fire resisting, and the aesthetic demand always leads to numerous cost. Moreover, large-space steel structure could not adopt the fire-resistance design method for common steel structures. The research on its fire-resistant behavior and calculation method is still inadequate, in addition, the relevant provisions covered in current code has little involved. Therefore, it is of vital importance in theory and engineering practice to further understand the fire-resistance performance and calculation methods of large-space steel structures. Theoretical analysis and numerical simulation have been carried out hereby to investigate the temperature distribution and structural behavior under fire conditions. The geometric and material nonlinear properties are extensively considered. Practical fire-resistant calculation methods for several types of large-space steel structures have also been proposed in this paper. The main research work covered in this paper includes:(1) The simplified method of establishing fire model in large-space structure numerial simulation is given in terms of comparisons with experimental results. The main influencing factors of non-uniform temperature distribution are systematically analyzed. Whether several calculation methods can be applied for calculations of air temperautre around roof has also been studied.(2) The calculation methods for large-space steel structures'performances under fire conditions have been discussed. Material properties of structural steel and high-strength steel cables enduring high temperature are determined by contrasting analysis. The validity of this method has been extensively explained by studying structural performances of gable frames considering fire influences.(3) The modified equivalent sandwich plate method calculation method for calculating vertical displacement of quadrangular pyramid grid structures under fire conditions is given. Based on studying influcnce factors, critical temperature tables are given taking account of non-uniform temperature distribution. The simplified calculation formula for single-layer reticulated domes including temperature rise effects is obtained by researches on their elasto-plasticity bearing capacities.(4) The calculation formulae for vertical displacement and prestressed force variation of cable truss and cable nets are deduced in theory. Fire-resistance characteristics are obtained of beam string structure relying on finite element analysis. The critical temperatures determining principles for monolayer cable net of glass facades have been proposed. The critical temprature tables are obtained applicable to different spans, grid dimentions and cable diameters of monolayer cable net.
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