Vulnerability assessment of reinforced concrete structures for fire and earthquake risk - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 361

second scenario, the earthquake does not occur right after a fi re, as it is less
likely; an exception is in aftershocks when a fi re has already been ignited
due to the main shock. The case study is for a post-fi re seismic evaluation
scenario to perform a post-fi re structural damage evaluation and to assess
the residual seismic load capacity of the structures after fi re. Although the
information provided here would be useful for developing an understand-
ing of the performance of different structural systems in fi re and earth-
quake, the scope of this chapter is limited to reinforced concrete building
structures, constructed with normal strength concrete.
14.2 Structuralresponsetofi re
Response of structures to fi re is typically evaluated using a fi re resistance
approach. A common approach for fi re endurance assessment of structures
is to implement a full-scale fi re resistance test. One of the fi rst fi re resis-
tance/endurance tests was carried out using an experimental method in
Denver, Colorado, in 1890 (Harmathy, 1993). There are now standards, such
as E119 'Standard Test Methods for Fire Tests of Building Construction and
Materials,' that describe how a fi re resistance test can be performed.
Although application of the new performance-based approach is permitted
by some of the design codes, since few assessment tools are available and
accessible to practitioners, it is not widely being used for evaluation of fi re
resistance. A large number of fi re resistance tests have been carried out,
since the development of the E119 standard. The purpose of these tests was
to better understand how structural elements and assemblies, such as
columns, beams, fl oors and walls, perform during a fi re. The results of these
tests led to the development of requirements for fi re resistance design of
structures.
There are many factors that contribute to the fi re resistance of a building
structure; the higher the fi re load, the lower the fi re resistance. Increase of
temperature normally results in the reduction of mechanical properties of
the materials, such as compression/tensile strength and modulus of elastic-
ity. Thermal expansion of structural elements is another major effect from
fi re. It results in inducing large deformation to the structural elements and
could cause considerable damage to the structural members even far from
the fi re compartment. When the structure cools after a fi re, it suffers more
damage due to shrinkage of the elements from the rapid temperature drop
after the fi re. Various studies and research have been carried out to assess
structural response and damage due to fi re. However, there are still gaps in
the availability of appropriate tools for performance evaluation and design
of the whole structural systems in fi re.
A new emerging performance-based fi re resistance evaluation of struc-
tures emphasizes the consideration of response and behavior of the whole