Abstract:

Three full-scale reinforced concrete space frames with specially-shaped columns were tested following the ISO834 standard heating process, and the influences of loading level and beam-to-column stiffness ratio on the failure mode, displacement-time curve and fire resistance of the specimens were investigated. Experimental results show that   the frame beams in the failure stage reveal a force pattern similar to catenary action;   the horizontal linear displacement of the frame joints in different directions are closely related to the axial expansion of the adjacent frame beam in the same direction;   when the frame beam keeps unchanged, the rotation of beam-tocolumn joints obviously decreases and even becomes opposite with the increase of column stiffness ratio in the middle and later stages of the test ; and   high loading levels make the specimen reach its fire resistance more easily, but the beam-to-column stiffness ratio has no obvious ,effect on fire resistance. It is thus concluded that the research on the fire resistance of a total structure is more convenient to the investigation of fire performance of the structure and its components.

Key words: reinforced concrete, specially-shaped column, space frame, elevated temperature, mechanical property