Passive Fire Protection. Federal Building and Fire Safety Investigation of the World Trade Center Disaster.
Passive Fire Protection. Federal Building and Fire
Safety Investigation of the World Trade Center Disaster.
Carino, N. J.; Starnes, M. A.; Gross, J. L.; Yang, J.
C.; Kukuck, S. R.; Prasad, K. R.; Bukowski, R. W.
NIST NCSTAR 1-6A; 326 p. September 2005.
World Trade Center; high rise buildings; building
collapse; disasters; fire safety; fire investigations;
terrorists; terrorism; fire protection; fire resistance;
thermal response; thermophysical properties; adhesive
strength; building codes; cohesive strength;
construction; density effects; thickness; heat capacity;
fire resistive materials; thermal conductivity; thermal
This report deals with the passive fire protection used
in the World Trade Center (WTC) towers. The main
objective is to provide background information that can
be used to assess the in-place conditions of the passive
protection before and after aircraft impact. The report
includes a review of key building code provisions
related to structural fire protection. It also includes
a review of key decisions related to passive fire
protection made during design, construction, and
occupancy of the towers. Copies of documents to support
key findings are included in an Appendix. A summary is
provided of available data on in-place measurements of
the sprayed fire-resistive materials (SFRMs) applied to
the floor trusses and to core members. Measurements of
thermoplastic properties of the passive fire protection
materials, including gypsum panels, are presented. The
effects of gaps in thermal insulation and the effects of
variability of insulation thickness are evaluated. The
rationale for selecting the effective thickness of
thermal insulation for use in thermal-structural
analyses is presented. Measurements of adhesive and
cohesive strengths of a selected SFRM are summarized.
Simplified models are presented for estimating the
acceleration required to dislodge SFRM from planar
surfaces and encased round bars. The report concludes
with a summary of key findings.