Effects of Large Section Size and Fire Resistant Steel on Redundancy Improvement of Steel High-Rise Buildings in Fire

Abstract

Structural safety of high-rise steel buildings in fire circumstances depends highly on the behavior of their columns. Real behavior of large section columns which are commonly used in such buildings, however, is not known well because of a lack of appropriate fire test facilities to conduct full-scale experimental investigation. Behaviors of a total of seven large steel columns in fire are investigated experimentally using a high-performance column furnace in the Building Research Institute of Japan. Several findings to improve the structural redundancy of steel buildings in fire circumstances are discussed. They include: that properly protected large steel columns show high fire resistance; however, if a portion of fire protection is damaged, even a large section column can surrender far earlier than expected; ceramic fiber blanket is one of the good options for robust protection; keeping axial load ratio of columns smaller is effective for fire resistance improvements; usage of high-performance steel grade, such as fire resistant steel, improves the fire resistance of columns greatly, hence the fire redundancy of a building.