After The Smoke Clears:
Assessment of Fire-
Damaged Concrete
Structures
By Ir. Mohd Firdaus bin Mohd
Civil and Structural Engineering Branch
Public Works Department
A
fter a fire incident, the question that is
usually raised is whether the damaged
building can be reinstated and reused?
Fortunately, reinforced concrete structures are
able to survive a fire event. However, a structural
assessment must precede the reoccupation
of the building. The purpose of a structural
assessment is to investigate the residual strength
of the affected structural elements, so they can be
restored or demolished.
Before an assessment is carried out, the
safety of the personnel who are assigned for that
purpose must be assured. Therefore, any part of
the building that may be at risk of collapse must
be propped up immediately and this step must not
be taken lightly.
During an assessment, information on the fire
is very crucial. For example, the intensity of the
fire which was imposed on the structural element
must be found out to ascertain its existing capacity
and condition. This information should include
the types of building elements and materials, the
point where the fire initiated, exposure conditions,
estimated fire temperature, the duration of fire and
other possible data. With these data, the severity
level of any damage may be estimated.
There are guidelines to assist the investigator
in the assessment process, such as the Technical
Report No. 68 by The Concrete Society. Figure
1 shows the stages of assessment and repair
process which can be found in the report. However,
this article is focused on methods for measuring
on-site residual strength and deformations, and
to obtain evidence of estimated temperatures
reached during the fire.
What happens to Reinforced Concrete
when exposed to fire?
Reinforced concrete changes physically,
mechanically, and also chemically when exposed
to certain temperatures. These behaviour traits
are important in predicting damage severity.
Therefore, visual inspection is the primary on-site
investigation technique employed in estimating
the extent of any damage.
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