Abstract: 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.

Key words: stainless steel, umbrella structure, fire test, smoke temperature, temperature of stainless steel members, displacement response