Thermal Performance of Fire Resistive Materials III. Fire Test on a Bare Steel Column.
Thermal Performance of Fire Resistive Materials III.
Fire Test on a Bare Steel Column.
Bentz, D. P.; Hanssen, L. M.; Wilthan, B.
NISTIR 7576; 83 p. April 2009.
steel columns; fire resistant materials; fire tests;
time; temperature; thermocouples; thermometers;
methodology; high temperature; ASTM E119; heat transfer;
emissivity; exposure; standards
This report is part III in an ongoing series concerning
the characterization and modeling of the thermal
performance of fire resistive materials (FRMs). In part
1, a methodology for characterizing FRMs to provide
quantitative material property inputs for thermal
performance models was outlined, and in part 2, one such
multi-layer model was demonstrated for simulating the
results of high temperature slug calorimeter experiments
conducted in a small furnace. Attempts to extend the
one-dimensional model to predict the performance of
FRM-insulated steel columns in a standard ASTM
International E119 fire exposure were successful only
when a safety (viewing) factor of approximately 0.5 was
introduced for reducing the radiative heat transfer
between the fire and the protected column. To justify
this fitted value of the viewing factor, a simpler fire
test of a single bare W14x233 structural steel column
was conducted in the column furnace at a commercial
U.S.-based testing laboratory. This report presents the
results of that test, along with an analysis based on a
previously developed general heat balance equation. The
emissivity value that provides the best fit to the
experimental data is contrasted against the measured
emissivity of the structural steel. The resultant safety
factor is found to be on the order of 0.45, in general
agreement with the value used previously in the one
dimensional thermal model. One unique feature of this
study is that data was also collected during the (slow)
cool down period that followed the termination of the
fire exposure, allowing a comparison of the convective
heat transfer coefficients during a fire exposure and
subsequent cooling in a furnace environment. Additional
thermocouples were placed on the steel column and the
furnace walls and two plate thermometers were placed
near the surface of the steel column to better
characterize the furnace fire environment. All of the
measured data is provided in an Appendix to place it in
the public domain where it may serve as a reference data
set for other researchers.