STRUCTURAL RESPONSE OF RC SPATIAL FRAME WITH SPECIALLY-SHAPED COLUMNS AT ELEVATED TEMPERATURE

The paper presents the results of three spatial frames with specially-shaped columns (SSC-frame) subjected to high temperature. A finite element model is described for studying the behaviours of three-dimensional structures at ambient and high temperatures, in which both geometrical and material non-linearities are taken into account and the transient thermal strain for concrete, and unloading, thermal expansion, creep and degradation of material for both materials with elevated temperatures are included. The program has then been validated by comparing with experimental results, which indicate that the program is capable of predicting the fire resistance of RC frames with an accuracy that is adequate for practical purposes. At the end of the paper, three groups of SSC-frames are conducted using the program to find the influence of the main parameters, including beam-column stiffness ratio and loading level, to the mechanical behaviours of space RC frames with specially-shaped columns at elevated temperatures.