| Title |
Experimental Study on the Determination of Fire Protection Thickness through Section Factors of Structural Steels |
| Keywords |
structural element ; section factor ; fire protection ; fire test |
| Abstract |
Traditionally, the thickness of fire protection materials of structural elements such as beam and column have been decided by fire test using the predominant steel section of H-300x300x10x15 for column and H-400x200x8x13 for beam in Korea. But this way of determination of fire protection thickness yields very unduly results. Because the temperature-increment rate of structural steel elements depends mainly on magnitude of their cross-areas. In general, the thicker size of cross-areas for structural elements, the lower temperature shows up. It had already proved that the fire protection thickness only depends on the size of cross-areas and the fire protection method for three-side or four-side exposed conditions in European countries, New Zealand, Australia, the United State of America and so on. To demonstrate there would be differences among various cross-areas of structural steel, we conducted several fire tests with full-scale specimens of beams and columns. For the determination of critical temperature for steel sections when the fire resistant performance is needed to be decided, we conducted with a loaded fire test for beam and column, respectively. Finally, the small column in 1.0meter length and beam in 1.5 meter length were used in order to deprive the rational fire protection thickness of structural elements such as beam and column, respectively. After lots of fire tests we could obtain there were significant temperature lags between higher cross-areas and lower cross-areas. The critical temperature of steel as a criterion is decided as 538℃ from the figures deprived from the load tests and the 538℃ defined at the KS 2257-6,7. We could consider that the best way of determination of fire protection thickness is using the following multi-regression equation which was deprived from several fire tests using the concept of section factor, FR = 0.15 + 2225.40t + 60.09t(where, FR means fire resistant time, t means thickness, A means cross-area and means heated parameter) |