Fire Endurance of Concrete-Protected Steel Columns

Abstract

An empirical formula is developed for the pre­ diction of the endurance of concrete-protected steel columns. Fire endurance is interpreted as the time during a standard test required for the temperature of the steel core to reach I 000 F (538 CJ. In the light of numerous test results, the accuracy of the formula appears to be satis­ factory. A numerical example is included to show the application of the formula. temperature. • IN A RECENT PUBLICATION1 the authors described a numerical procedure by which the temperature history of protected steel columns can be calcu­ lated during exposure. The most important information that one can derive from such a nu­ merical study is fire endurance, i.e., the time at which structural failure of a column occurs during a standard test. As the direct cause of structural failure is the buckling of the load-bearing steel core of the col­ umn, calculations aimed at predicting time of failure in a standard exposure should normal­ ly consist of two steps: the calculation of the temperature history of the column, followed by a study of its stress-deformation history. The re­ sults of numerous tests indicate, however, that structural failure usually occurs when the average T. T. Lie is a research officer with the Fire Section, Di­ vision of Building Research, National Research Council of Canada, a gradu.ate in Engineering Physics of the Technical University of Delft. He worked as a physicist in the Organi­ zation for Applied Scientific Research. T. N.. 0., in Holl~nd from 1954 to 1967 and studied on a fellowship at the Bu.ld­ ing Research Institute in Japan during 1962. Mr. Lie is .a+ present engaged in research in the field of struc.+ural _f>re protection and has published several papers on th1s subJect and is author of a book on Fire and Buildings.