ABSTRACT
An important criterion for the design of CFST structures, besides the serviceability
and load-bearing capacity, is fire resistance. The required fire resistance depends
on the type of building (e.g. less than three storeys or high rise), which varies from
less than 30 minutes to three hours. The fire resistance of unprotected rectangular
hollow section (RHS) or circular hollow section (CHS) columns is normally found
to be less than 30 minutes. There are several methods to increase the fire resistance
of tubular columns, such as applying external insulation, concrete-filling and
water-filling (Twilt et al. 1995). The increase in fire resistance due to concrete-
filling is demonstrated in Figure 1.10(e).
