不锈钢伞状结构火灾响应试验研究

Experimental study on fire behaviour of stainless steel umbrella structure

为研究不锈钢伞状结构在实际火灾下的整体响应,考虑不同的火源位置,采用正庚烷油池火对一1∶4不锈钢伞状结构缩尺模型开展了2次局部火灾试验。试验过程中测量了试验模型关键位置的烟气温度、不锈钢构件的温度和位移。试验结果表明:在下方着火情况下,空间结构温度场呈不均匀分布,热烟气温度峰值从火源正上方向四周逐渐减小,呈现明显梯度。不锈钢构件的温度变化除火源正上方及周围杆件的测点温度明显上升外,其他测点温升有限,不超过50℃。在两次试验过程中,靠近火源一侧的梁产生了向上的位移,远离火源一侧的梁则对称地产生了向下的位移,伞架结构整体向远离火源一侧倾斜;不锈钢柱受热不均匀,受火侧和背火侧竖向膨胀位移相差0.56 mm;结构变形受火源位置影响不大,两个工况最大位移接近,变形均在试验结束后基本恢复,且未观测到影响结构宏观承载性能的永久变形。

In order to study the overall response of the stainless steel umbrella structure to actual fire,two localized fire tests were carried out using a 1∶4 scale model with n-heptane pool fires at two different fire locations.The smoke temperature,the temperature and the displacement of the stainless steel members at the key positions of the model were measured.The experimental results show that the temperature field of space structure presents uneven distribution during both fire tests,and the peak smoke temperature decreases gradually from the center line of the fire source,showing an obvious gradience.The temperature rising of stainless steel member is limited and does not exceed 50℃,except for the joints of rods directly above and around the fire source.In the course of the two fire tests,the beams on the fire side show upward displacement,and the beams on the other side from the fire show downward displacement symmetrically,and therefore the whole umbrella frame structure tilts to the side away from the fire;Stainless steel columns are not heated uniformly,and the difference of vertical expansion displacement between fire-exposed side and unexposed side is 0.56 mm;Structural deformation affected by the location of fire sources is not significant,and the maximum displacements in the two fire scenarios are very closed.The structural deformation was basically recovered after the tests,and no permanent deformation affecting the macroscopic bearing performance of the structure was observed.