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Structural Steel Frames 291
Rib beams
Universal
column
Steel deck spans
across rib beams
Concrete
floor cast on
steel deck
Spine
beams
Rib beams
Duct for services
between beams
Spine beams
supported by
channel section
brackets welded
to column
Universal column
section
Rib beams support steel
deck and concrete floor
Duct for services
over spine beams
Figure 5.14 Parallel beam structural steel frame.
The parallel beam structural frame may be used, with standard I-section beams and
columns or with hollow rectangular section columns and light section rolled steel sections
or cold-formed strip steel beams and ribs, for smaller buildings supporting moderate floor
loads in which there is a need for provision for the full range of electric and electronic
cables and air conditioning. Although the number of steel sections used for each grid of
the framework in this system is greater than that needed for the conventional steel frame,
there is generally some appreciable saving in the total weight and, therefore, the cost of the
frame, and appreciable saving in the erection time due to the simplicity of connections.
The overall depth of the structural floor is greater than that of a similar conventional
structural steel frame. Services may be housed within the structural depth, rather than
being slung below the structural floor of a conventional frame above a suspended ceiling,
which can help to reduce the overall height of the building for a given clear height between
the finished floor and ceiling level.
Pin-jointed structural steel frames
The shortage of materials and skilled craftsmen that followed the Second World War
encouraged local authorities in the UK to develop systems of building employing standardised
components that culminated in the Consortium of Local Authorities Special Programme
(CLASP) system of building. The early development was carried out by the
Hertfordshire Country Council in 1945 in order to fulfil their school building programme.
A system of prefabricated building components based on a square grid was developed, to
utilise light engineering prefabrication techniques, aimed at economy by mass production