Research Trends and Results

Real-scale fire test of a Three-Story wooden
School Building (final experiment)
TOMOHIRO Naruse (Dr. Eng.), Head,NII Daisaku (Dr. Eng.) , Senior Researcher
Fire Standard Division, Building Department
ANDO Koji, Head,TOJO Akira, Researcher,Standard and Accreditation System Division, Building Department(Key words) Timber construction, real-scale fire experiment, fire safety
1. Foreword
In October 2010, a law with regard to theacceleration of timber utilization in publicbuilding structures and so on was enforced.
Taking this into account, NILIM collects datanecessary for re-examination of fire prevention
related provisions of the Building Standards
Law in regard to three-story wooden schoolbuilding and has been carrying out studies toprepare a basic draft based on it.
2. Objective of final experiment
To start with, with specifications presumed asa school, and in addition, using a building withthe lowest level required for buildings including
other usage, we carried out a real-scale fire
experiment of three-story wooden schoolbuilding in NILIM’s site, on February 22, 2012,
and fire spread to the upper floor in the earlystage of fire, via external openings from theroom on the ground floor where the fire brokeout, then quickly spread to the next rooms
through external and internal openings of fire
prevention walls, and problems of the collapseof fire prevention walls to independently beerected after fire and so forth were made clear.
In consideration of these problems, we carriedout a real-scale fire experiment (preparatoryexperiment) on November 25, 2012 in Gero
City, Gifu Prefecture, and confirmed theeffectiveness of countermeasures such as use offire prevention material for interior finishes,
installation of balconies and canopies andchanges in structure of fire prevention walls andfire prevention doors.
Based on this result, we prepared requirementsfor performance for three-story wooden schoolbuilding to prevent the rapid spread of fire toupper floors, prevent the fall of structures during

the period required for evacuation and rescues
and prescribe specifications necessary for those,
and we implemented an real-scale fireexperiment (herein after referred to as “finalexperiment”) in order to finally corroborate theperformance, on October 20, 2013, in Gero City,
Gifu Prefecture. In this experiment, in order toprevent rapid spread of fire to upper floors, weprovided a specification to make the interior,from which the fire broke out, fireproof toprevent fire spread.
3. Outline of final experiment’s result
After the fire broke out in the room on theground floor, although it spread to the peripheryof the combustible materials from the firesource, and continued to the extent flamesreached to the ceiling, it took 48 minutes until
the fire widely spread in the room where the fire
broke out to confirm the effect of fire spread
which was one of the objectives of theexperiment. The fire spread to the inside of aroom on the second floor 15 minutes thereafter
via exterior openings and spread to the inside ofa room on the third floor via exterior openings
four minutes after that. At a point in time morethan an hour after the spread of fire, fire
extinguishing was carried out.
In view of this result, the fire spreading toupper floors via external openings could beprevented, fire spreading from the room the fire
broke out to the stair room and fire spreading
via the fire prevention wall did not occur,
despite columns and beams in the room fromwhich the fire broke out being chared to a depth
up to 4-7cm, and the test body did not collapsed,and besides, in consideration of the fact that
there was no disruption of fire prevention walls,
effective specifications with regard to therequired performances for the standards draft
could be corroborated and other data could becollected.
4. Conclusion
As a result of three real-scale fire experiments
including final experiment implemented so far,and based on experiment results of relevant
members, we are prepared to compile details of astandards draft.
This experiment was carried out under thecollaborative studies with Waseda University,
Akita Prefectural University, Mitsui Home Co.,
Ltd., Sumitomo Forestry Co., Ltd., Gendai
Keikaku Kenkyusho Co., Ltd., Building
Research Institute and National Institute for Landand Infrastructure Management.
[Reference]
In reference to the results of the three real-scale
fire experiments, we would like you to refer tothe following URL.
http://www.nilim.go.jp/lab/lab/bbg/kasai/h23/top.
htm

Photo 1: Fire spread to the 2nd floor

Photo 2: Fire spread to the 3rd floor