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208 Barry’s Advanced Construction of Buildings
Photograph 4.19 Fabricated steel hexagonal space frame.
Composite frame construction
A composite frame construction comprises prefabricated concrete and steel components,
usually offered by one supplier as part of a design, manufacture and erection service for
both single- and multi-storey-framed buildings. Precast reinforced concrete structural
beams and columns are used to support lattice steel roof beams. The columns and beams
are precast under carefully controlled factory conditions, with frame joints and base fixings,
etc., cast in as necessary. The advantage of the composite frame construction is that the
reinforced concrete columns and beams provide good fire resistance to the main structure
and the lattice steel roof provides a lightweight covering. Economy of initial build cost can
be made in the extensive use of prefabricated units.
Figure 4.48 is an illustration of a typical two-bay, single-storey composite frame structure.
The precast reinforced concrete columns, which have fixed bases, serve as vertical
cantilevers to take the major part of the loads from wind pressure. Steel brackets, cast into
the column head, support the concrete and lattice steel roof beams. Concrete or lattice steel
spine beams are used under the roof valley to provide intermediate support for every other
roof beam. The top of the lattice steel roof beams, which are pitched at 6° to the horizontal,
supports the low-pitch profiled steel roof sheeting. Fixing slots or brackets cast into the
columns provide a fixing and support for sheeting rails, which in turn support the profiled
steel cladding to the walls.