Buckling Strength of Steel Columns with Induced Deformation at Increasing High Temperature

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An experimental and analytical study was conducted to evaluate the effects of induced joint translation angle R caused by the thermal elongation of connected heated steel beams on the buckling strength of steel columns.Two sets of buckling tests were performed using steel columns (SN490B JIS grade) with a rectangular cross-section: (1) one at a constant high temperature and (2) the other at increasingly higher temperatures under a constant axial load.The first experimental study, using tests at a constant high temperature, indicated that the reduction of the maximum axial load Pmax due to induced deformation R can be up to 15% at room temperature, but, at above 400℃, the column failure axial load is only slightly lower man that without inducing the deformation.The second experimental study, using tests at increasingly higher temperatures under a constant axial load, indicated that the reduction in the column failure temperature Tcr due to induced deformation R can be from 10℃ to 50℃, depending on the axial force ratio from P/P_<yRT>=0.2 to 0.5.The results of these tests were simulated by a one-dimensional finite-element procedure developed by the author, and it was shown that numerical analysis can be used to provide accurate predictions of the buckling characteristics of columns with an induced deformation at high temperatures when an appropriate mechanical model and data of steel materials at high temperature are used.