A study of the effect of partial loss of protection on the fire resistance of steel columns

Missing fire protection material on steel structural members is generally recognized as a problem, though little information is available to quantify the effect. A finite element heat transfer analysis is used to compare the thermal response of steel columns with lost protection material when exposed to the ASTM E-119 furnace environment. Based on the predicted thermal response and using thermal endpoint criteria specified in ASTM E-119, estimates are made of the fire resistance of each column with varying amounts of missing protection. Relatively small proportional losses of fire protection material are required before significant reductions in fire resistance are realized. The degradation in fire resistance is most significant for light-weight columns and for cases where the fire protection material is missing from the flange rather than web.