From the beginning structural
steel framed construction proved to be the most economical support system for
multi-stories high rise structures. But does this economy carry over into
low-rise commercial and industrial facilities? The answer is yes. Up until
about 1970. Cost studies found that low rise commercial structures such as
office buildings, schools and department stores with superstructures of conventionally
formed concrete were often as economical as
steel framed construction. But in
the early 1970’s rising labor cost made structural steel framing systems even
more economical because they could be prefabricated in the shop and
then quickly erected by relatively by small
field crews. By contrast, cast in place concrete superstructures required more
labor. When comparing the two methods, it was common to find savings of $1.50
to $2.00 per square foot or
more by
using structural steel.
Until the present, the structural
steel framing system continues to be economical for virtually all types of
commercial and industrial building structures. The three primary reasons are:
- The
availability of higher strength steel such as A992 grade 50 steel, which has become
the dominant material specification for wide-flange shapes (better know as
w-shapes).
- Increased
speed of production, made possible through a construction method called fast
track scheduling.
- The
lower cost of materials due to to the implementation of the design method known
as load and resistance factor design (LRFD).