FIRE RESISTANCE OF STEEL TUBULAR COLUMNS INFILLED WITH ULTRA-HIGH STRENGTH CONCRETE

摘要

Ultra-high strength concrete filled steel tubular columns (UHSCFT) with compressive strength more than 100 MPa are an attractive option for high-rise buildings and several such applications have been seen in modern construction around the world. The compressive strength of ultra-high performance concrete/cement composite could reach as high as 180 N/mm(2). This paper investigates the fire resistance of externally protected ultra-high strength concrete filled tubular columns exposed to the standard ISO fire. Numerical analyses were carried out using a general finite element analysis software and the results were validated against the test results in terms of heat distribution and thermal-mechanical behavior. Comparison with the test results showed a reasonable agreement with finite element results in terms of temperature prediction and load displacement behavior during the fire. Finally, based on the validated finite element model, further numerical investigations were carried to study the effects of fire protection thickness, load ratio, the strengths of concrete and steel, steel contribution ratio, relative slenderness ratio and the steel section diameter on the fire resistance of ultra-high strength concrete filled tube columns.