Study On Fire Resistance Design Of Steel Structures

The steel structures are widely used in modern building structures due to its advantage properties such as high strength, light weight and so on. However, the poor fire-resistant ability is also the weakness of the steel structures, in which its yield strength, when the temperature is up to 400℃, would decrease the half of the yield strength at the normal temperature, and the steel will lost most of its strength and rigidity when the temperature up to 600℃. Therefore, it is very important in the theory and practice to study the problem of fire resistance and fire protection of the steel structures. In the paper, the test-based and calculation-based fire resistance design methods of the steel specimens are stated firstly. The test-based fire resistance design method of the steel specimens is based on a lot of test data, in which the fire-resistant time may be determined according to different fire protection measures and the fire protection measures in the structural fire design can be chosen directly according to the fire-resistant time of the steel specimens. Though the test-based fire resistance design method is simplified and visualized, the influence of the magnitude and distribution of loads and the end restriction conditions of the steel specimens on its fire-resistant time cannot be considered. The calculation-based fire resistance design method of the steel specimens is based on the theory of Finite Element Method (FEM), so it is a more reasonable design method in which the influence of the arbitrary magnitude and distribution of loads and the end restriction conditions of the steel specimens on its fire-resistant time can be considered, which is more coincided with the practical case. After the analysis and comparison for the two fire resistance design methods, the fire resistance design for an actual steel frame structure is performed using the calculation-based fire resistance design method.Finally, some conclusions are given as the fire resistance design using the calculation-based fire resistance design method, in which the thickness of protective layer can be calculated iteratively as to ascertain the most economical thickness, is more economical and simple than that using the test-based fire-resistant design method.