Thermal gradients in columns subjected to fire

<p><span style="background-color:rgb(253, 252, 247); font-family:helvetica neue,helvetica,arial,sans-serif; font-size:12.8000001907349px; font-style:normal; font-variant:normal; line-height:15.3600006103516px">Four axially loaded steel columns were tested under non-uniform heating conditions to experimentally evaluate the thermal gradient effects on the fire resistance (temperature and failure time) of steel columns with pinned ends. Each column length is nominally equal to 12 feet. Two different I-shapes (W8x35 and W14x53) made of ASTM A992 were used.  Column ends were designed as pinned-pinned conditions  to allow rotation about the weak-axis. Various fire protection scheme and heating rates were applied to create the thermal gradient through the cross-section. Test data includes the steel temperature-time responses at various cross-sections along the heated length of the column specimen. Test results indicate that thermal gradients through cross-sections can lead to a significant increase in lateral displacements due to thermal bowing, which can develop the secondary moment effects in the early stage of heating, and can be eventually reduce the fire resistance of steel columns.</span></p>

针对四根轴向受荷且端部铰支的钢柱，研究人员在非均匀受热条件下开展了抗火试验，以此评估温度梯度对该类钢柱抗火性能（温度与失效时间）的影响。